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Point-of-Care Ultrasound (POCUS) for the Cardiothoracic Anesthesiologist

Open AccessPublished:January 16, 2021DOI:https://doi.org/10.1053/j.jvca.2021.01.018
      Point-of-Care Ultrasound (POCUS) is a valuable bedside diagnostic tool for a variety of expeditious clinical assessments or as guidance for a multitude of acute care procedures. Varying aspects of nearly all organ systems can be evaluated using POCUS and, with the increasing availability of affordable ultrasound systems over the past decade, many now refer to POCUS as the 21st-century stethoscope. With the current available and growing evidence for the clinical value of POCUS, its utility across the perioperative arena adds enormous benefit to clinical decision-making.
      Cardiothoracic anesthesiologists routinely have used portable ultrasound systems for nearly as long as the technology has been available, making POCUS applications a natural extension of existing cardiothoracic anesthesia practice. This narrative review presents a broad discussion of the utility of POCUS for the cardiothoracic anesthesiologist in varying perioperative contexts, including the preoperative clinic, the operating room (OR), intensive care unit (ICU), and others. Furthermore, POCUS-related education, competence, and certification are addressed.

      Keywords

      POINT-OF-CARE ULTRASOUND (POCUS) is the use of portable bedside ultrasound imaging for a variety of expeditious clinical assessments or as guidance for a multitude of acute care procedures. With the increasing availability of affordable ultrasound systems over the past decade, POCUS use has burgeoned over a similar time frame, with low-cost portable systems now considered the 21st-century stethoscope.
      • Bryson GL
      • Grocott HP.
      Point-of-care ultrasound: A protean opportunity for perioperative care.
      ,
      • Gillman LM
      • Kirkpatrick AW.
      Portable bedside ultrasound: The visual stethoscope of the 21st century.
      Ideally, POCUS use in clinical management should be goal-directed, rapid, and reproducible. Varying aspects of nearly all organ systems can be evaluated using POCUS (see Table 1), and there are increasingly more clinical conditions in which the utilization of POCUS may have a role.
      • Kimura BJ.
      Point-of-care cardiac ultrasound techniques in the physical examination: Better at the bedside.
      ,
      • Novitch M
      • Prabhakar A
      • Siddaiah H
      • et al.
      Point of care ultrasound for the clinical anesthesiologist.
      In particular, this growth has been accelerated further with the availability and accessibility of small handheld ultrasound devices. In certain clinical contexts (eg, pneumothorax [PTX], hemidiaphragmatic paresis), POCUS has superior diagnostic sensitivity and specificity compared to other diagnostic modalities, while also mitigating the higher costs and possible radiation side effects of non-ultrasound imaging.
      • Houston JG
      • Fleet M
      • Cowan MD
      • et al.
      Comparison of ultrasound with fluoroscopy in the assessment of suspected hemidiaphragmatic movement abnormality.
      Various medical societies (eg, Society of Critical Care Medicine, American Society of Echocardiography) have developed POCUS guidelines for its usage across a wide range of clinical settings.
      • Frankel HL
      • Kirkpatrick AW
      • Elbarbary M
      • et al.
      Guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients–part I: General ultrasonography.
      ,
      • Spencer KT
      • Kimura BJ
      • Korcarz CE
      • et al.
      Focused cardiac ultrasound: Recommendations from the American Society of Echocardiography.
      Table 1Common Point-of-Care Ultrasound (POCUS) Applications
      POCUSStructuresUtility
      AirwayCTM, tracheaCricothyroidotomy, endotracheal intubation
      Breathing (lung)Pleura, lung, diaphragmPneumothorax, lung parenchymal disease, pleural effusion, pulmonary edema
      Circulation (cardiac)LV, RV, cardiac valvesMyocardial ischemia, CHF, valvular lesions
      PericardiumTamponade
      Aorta & aortic archAneurysm and dissection
      GastricAntrumGastric volume and contents
      VascularVeinsCentral and peripheral venous cannulation
      ArteriesInvasive monitoring, IABP
      IVCVolume status
      VExUS scanFluid overload
      Deep veinsDVT
      Abbreviations: CHF, congestive heart failure; CTM, cricothyroid membrane; DVT, deep vein thrombosis; IABP, intra-aortic balloon pump; IVC, inferior vena cava; LV, left ventricle; POCUS, point-of-care ultrasound; RV, right ventricle; VExUS scan, venous excess ultrasound scan.
      Cardiothoracic anesthesiologists routinely have used portable ultrasound systems for nearly as long as the technology has been available, particularly as a tool to guide vascular access procedures and for echocardiographic applications. Since transesophageal echocardiography (TEE) is used routinely by most cardiothoracic anesthesiologists, POCUS applications are a natural extension of existing practice.
      • Ramsingh D
      • Bronshteyn YS
      • Haskins S
      • et al.
      Perioperative point-of-care ultrasound: From concept to application.
      ,
      • Ursprung E
      • Oren-Grinberg A.
      Point-of-care ultrasound in the perioperative period.
      This narrative review presents a broad discussion of the utility of POCUS for the cardiothoracic anesthesiologist in varying perioperative contexts, including the preoperative clinic, the operating room (OR), and intensive care unit (ICU). Furthermore, POCUS-related education, competence, and certification are addressed.

      Airway Ultrasound (AUS)

      POCUS of the airway is useful for identification of airway structures, such as the cricothyroid membrane (CTM), tracheal rings, cricoid cartilage, thyroid cartilage, and hyoid bone (see Table 2).
      • You-Ten KE
      • Siddiqui N
      • Teoh WH
      • et al.
      Point-of-care ultrasound (POCUS) of the upper airway.
      In difficult airway scenarios, identification of the CTM by AUS has been shown to be useful for cricothyroidotomy procedures (see Fig 1). Kristensen et al. demonstrated that the identification of the CTM by ultrasound had a higher success rate than traditional inspection and palpation methods.
      • Osman A
      • Sum KM.
      Role of upper airway ultrasound in airway management.
      ,
      • Kristensen MS.
      Ultrasonography in the management of the airway.
      The utilization of ultrasound for preprocedural identification of tracheal rings, as well as pre- and paratracheal anatomy and blood vessels (especially abnormal vasculature), is helpful in assisting with the correct location and safe placement of a percutaneous tracheostomy.
      • Alansari M
      • Alotair H
      • Al Aseri Z
      • et al.
      Use of ultrasound guidance to improve the safety of percutaneous dilatational tracheostomy: A literature review.
      ,
      • Ravi PR
      • Vijai MN
      • Shouche S.
      Realtime ultrasound guided percutaneous tracheostomy in emergency setting: The glass ceiling has been broken.
      AUS also is useful for performing airways blocks to facilitate awake fiberoptic intubations, improving airway and intubating conditions compared to blind tecnhiques.
      • Krause M
      • Khatibi B
      • Sztain JF
      • et al.
      Ultrasound-guided airway blocks using a curvilinear probe.
      ,
      • Ambi US
      • Arjun BK
      • Masur S
      • et al.
      Comparison of ultrasound and anatomical landmark-guided technique for superior laryngeal nerve block to aid awake fibre-optic intubation: A prospective randomised clinical study.
      Table 2Overview of Airway Ultrasound (AUS)
      POCUSStructuresTechniques
      AirwayCTMCricothyroidotomy
      Cricoid cartilageCricoid pressure for RSI
      Thyroid cartilageAirway blocks
      Hyoid boneAirway assessment
      Tracheal ringsPercutaneous tracheostomy
      EsophagusEndotracheal/esophageal intubation
      Abbreviations: CTM, cricothyroid membrane; POCUS, point-of-care ultrasound; RSI, rapid-sequence intubation.
      Fig 1
      Fig 1Ultrasound (US)-guided airway examination to identify the cricothyroid membrane (CTM). The image on the left demonstrates probe positioning for the performance of a US-guided airway examination, while the image on the right illustrates key anatomy seen in the airway US examination.
      AUS also has shown utility in confirming correct endotracheal tube placement and in discerning between esophageal and endotracheal intubation. With endotracheal intubation, a single bullet sign (single air-mucosal interface with increased posterior artifact shadowing) will be visualized, along with the presence of bilateral lung sliding. Esophageal intubation has a unique double-tract sign appearance and absence of bilateral lung sliding. In a systematic review by Das et al., the authors found that AUS had a pooled sensitivity of 0.98 (95% CI, 0.97-0.99) and pooled specificity of 0.98 (95% CI, 0.95-0.99) in confirming endotracheal intubation.
      • Das SK
      • Choupoo NS
      • Haldar R
      • et al.
      Transtracheal ultrasound for verification of endotracheal tube placement: A systematic review and meta-analysis.
      A meta-analysis by Gottlieb et al., which included 17 studies and a total of 1,595 patients, showed transtracheal ultrasonography was 98.7% sensitive (95% CI, 97.8-99.2) and 97.1% specific (95% CI, 92.4-99.0) in confirming endotracheal intubation, with a mean time to confirmation of 13 seconds (95% CI, 12.0-14.0).
      • Gottlieb M
      • Holladay D
      • Peksa GD.
      Ultrasonography for the confirmation of endotracheal tube intubation: A systematic review and meta-analysis.
      AUS is a valuable and reliable adjunct for endotracheal intubation in cardiac arrest situations in which the end-tidal CO2 is low.
      • Chou HC
      • Chong KM
      • Sim SS
      • et al.
      Real-time tracheal ultrasonography for confirmation of endotracheal tube placement during cardiopulmonary resuscitation.
      ,
      • Sahu AK
      • Bhoi S
      • Aggarwal P
      • et al.
      Endotracheal tube placement confirmation by ultrasonography: A systematic review and meta-analysis of more than 2500 patients.
      AUS has been described for the prediction and assessment of difficult airways and evaluation of the epiglottis and vocal cords.
      • Singh M
      • Chin KJ
      • Chan VWS
      • et al.
      Use of sonography for airway assessment: An observational study.
      ,
      • Ko DR
      • Chung YE
      • Park I
      • et al.
      Use of bedside sonography for diagnosing acute epiglottitis in the emergency department: A preliminary study.
      Skin-hyoid distance is known to predict difficult mask ventilation and difficult laryngoscopy, while the epiglottis-to-vocal cord space has been shown to correlate with Cormack-Lehane intubation grade.
      • Alessandri F
      • Antenucci G
      • Piervincenzi E
      • et al.
      Ultrasound as a new tool in the assessment of airway difficulties: An observational study.
      ,
      • Rana S
      • Verma V
      • Bhandari S
      • et al.
      Point-of-care ultrasound in the airway assessment: A correlation of ultrasonography-guided parameters to the Cormack-Lehane Classification.
      Specifically, the mean standard deviation of the minimum distance from the hyoid bone to skin surface was 0.88 (0.3) cm in the easy mask ventilation group versus 1.4 (0.19) cm in the difficult mask ventilation group. The mean of this distance increased according to the level of difficulty of mask ventilation and laryngoscopy. The distance of the epiglottis to the vocal cord space was found to be a better predictor of difficult laryngoscopy compared to the hyomental distance ratio. A distance from the epiglottis to vocal cords of more than 1.77 cm had 82% sensitivity and 80% specificity in predicting difficult laryngoscopy, whereas a hyomental distance ratio less than 1.085 had a sensitivity of 75% and specificity of 85.3% in this prediction. Additionally, AUS can be used for the application of cricoid pressure during rapid-sequence induction.
      • Gautier N
      • Danklou J
      • Brichant JF
      • et al.
      The effect of force applied to the left paratracheal oesophagus on air entry into the gastric antrum during positive-pressure ventilation using a facemask.

      Gastric Ultrasound (GUS)

      Perioperative aspiration prevention is an important consideration during any surgical or interventional procedure, as aspiration of gastric contents may lead to aspiration pneumonia, which is associated with high morbidity and mortality.
      • Bouvet L
      • Bellier B
      • Gagey-Riegel AC
      • et al.
      Ultrasound assessment of the prevalence of increased gastric contents and volume in elective pediatric patients: A prospective cohort study.
      Evaluation of fasting status or assuring adequate gastric emptying has occurred can be challenging in numerous circumstances, such as patients with altered mental status and those with certain chronic medical conditions (eg, gastroparesis, diabetes, or chronic renal failure and liver failure). Aspiration risk is particularly extant in the context of procedures performed with moderate or deep sedation without an ETT (ie, out-of-operating room transesophageal echocardiograph [TEE] examinations). GUS allows for the identification and measurement of gastric antral cross-sectional area, with accurate assessment of gastric volume and contents in both the supine and right lateral decubitus positions.
      • Perlas A
      • Van de Putte P
      • Van Houwe P
      • et al.
      I-AIM framework for point-of-care gastric ultrasound.
      ,
      • Perlas A
      • Chan VWS
      • Lupu CM
      • et al.
      Ultrasound assessment of gastric content and volume.
      Figure 2 illustrates probe placement and imaging of the gastric antrum.
      Fig 2
      Fig 2Ultrasound (US)-guided gastric scan to assess gastric volume and content. The image on the left demonstrates probe positioning for the performance of an US-guided gastric examination, while the image on the right illustrates key anatomy seen in the gastric US examination.
      A randomized control trial by Kruisselbrink et al., using simulated clinical scenarios in nonpregnant adults with a pretest probability of 50% full stomach, showed that bedside GUS had a sensitivity of 1.0 (95% CI, 0.925-1.0), a specificity of 0.975 (95% CI, 0-0.072), a positive predictive value of 0.976 (95% CI, 0.878-1.0), and a negative predictive value of 1.0 (95% CI, 0.92-1.0) in ruling out a full stomach in patients in whom the presence of gastric contents was ambiguous.
      • Kruisselbrink R
      • Gharapetian A
      • Chaparro LE
      • et al.
      Diagnostic accuracy of point-of-care gastric ultrasound.
      Using nomogram-based data derived from measured antral cross-sectional area and patient age, gastric volume can be predicted (see Table 3) by GUS.
      • Van de Putte P
      • Perlas A.
      Ultrasound assessment of gastric content and volume.
      In summary, GUS can be performed easily at the bedside to provide qualitative and quantitative assessment of gastric contents, aiding in the formulation of a safe anesthetic airway management plan to minimize aspiration risk.
      • Perlas A
      • Arzola C
      • Van de Putte P.
      Point-of-care gastric ultrasound and aspiration risk assessment: A narrative review.
      However, there are currently no major society recommendations to replace nothing -by-mouth guidelines with gastric ultrasound.
      Table 3Overview of Gastric Ultrasound (GUS)
      POCUSStructuresAssessmentAspiration Risk
      GastricGastric antrumGastric volume

      Gastric contents (liquids or solids)
      Low risk (<1.5 mL/kg)

      High risk (>1.5 mL/kg)

      High risk (solid)
      Abbreviations: POCUS, point-of-care ultrasound.

      Lung Ultrasound (LUS)

      Lung ultrasound (LUS) (see Table 4) involves the study of air-fluid interfaces in the lungs, as well as the interpretation of ultrasound artifacts.
      • Dietrich CF
      • Mathis G
      • Blaivas M
      • et al.
      Lung artefacts and their use.
      Different transducers, such as phased-array, convex, microconvex, or linear probes, are being used for LUS to optimize the artifacts based on the lung pathology to be determined and the patient's body habitus.
      • Gargani L
      • Volpicelli G.
      How I do it: Lung ultrasound.
      Longitudinal scanning is performed in six or eight zones for focused lung examinations, with transverse scanning recommended in areas of specific interest for further evaluation of pathology.
      • Lichtenstein D.
      Lung ultrasound in the critically ill.
      POCUS of the lung is indicated to evaluate dyspnea, hypoxia, hypotension, thoracic trauma, pleurisy, and chest pain.
      • Mayo PH
      • Copetti R
      • Feller-Kopman D
      • et al.
      Thoracic ultrasonography: A narrative review.
      International evidence-based consensus recommendations for point-of-care lung ultrasound from Volpicelli et al. have proven helpful in guiding the implementation, development, and standardization of LUS across a variety of clinical settings.
      • Volpicelli G
      • Elbarbary M
      • Blaivas M
      • et al.
      International evidence-based recommendations for point-of-care lung ultrasound.
      Figure 3 outlines a decision-making algorithm to guide the assessment of lung pathology with LUS.
      Table 4Overview of Lung Ultrasound (LUS)
      POCUSStructureAssessmentDisease
      Lungs (LUS)PleuraLung slidingPneumothorax
      Lung zonesA and B linesPneumonia, ARDS, pulmonary edema
      PLAPS pointLung basesPleural effusion, pneumonia
      DiaphragmDiaphragm functionWeaning/ventilation, diaphragmatic paresis/paralysis
      Abbreviations: ARDS, acute respiratory distress syndrome; PLAPS, posterior lateral alveolar pleural syndrome; POCUS, point-of-care ultrasound.
      Fig 3
      Fig 3Decision algorithm for guiding the assessment of lung pathology using LUS. LUS, lung ultrasound; DVT, deep vein thrombosis; PLAPS, posterior lateral alveolar pleural syndrome.

      Normal LUS Mechanics

      Normal lung aeration is characterized by lung sliding, described as movement of the parietal and visceral pleura sliding against each other at the pleural line (equivalent to a sea-shore sign on the M-mode Doppler evaluations), as demonstrated by Video 1. Normal lung parenchyma will have an A profile pattern, seen as regular, repetitive horizontal reverberation artifacts arising from air below the pleural line (Fig 4). When air is replaced with fluid, the image will show B lines, which are comet-tail artifacts (vertical hyperechoic lines arising from the pleural line and fanning down all the way to the bottom of the screen) demonstrated by Video 2.
      Fig 4
      Fig 4Normal lung ultrasound (LUS) images and A lines. Panel A demonstrates probe positioning for evaluation of ribs and pleura, while panel B demonstrates ultrasound visualization of these structures. Panels C and D demonstrate probe positioning and visualization of A lines, respectively.

      Abnormal LUS Mechanics

      When the ratio of fluid-to-air content increases, the number of B lines increases in lung zones accordingly, resulting in a B profile pattern. The presence of B lines rules out PTX.
      • Volpicelli G.
      Sonographic diagnosis of pneumothorax.
      Interstitial lung disease and pulmonary edema may be indicated by the number and distribution of B lines (lung rockets) in each zone (three or fewer in each lung zone is seen in a healthy lung). Absence of lung sliding in a particular lung zone should raise suspicion for PTX. The presence of lung point, defined as the appearance and disappearance of lung sliding with respiration at a particular point (equivalent to the M-mode stratosphere or barcode sign), is characteristic and pathognomonic for PTX, with a reported overall sensitivity of 66% and a specificity of 100% for the diagnosis of PTX.
      • Volpicelli G.
      Sonographic diagnosis of pneumothorax.
      ,
      • Lichtenstein D
      • Meziere G
      • Biderman P
      • et al.
      The “lung point”: An ultrasound sign specific to pneumothorax.
      Lung point is demonstrated in Video 3 and Figure 5, while an algorithm guiding the diagnosis and exclusion of PTX using LUS is illustrated in Figure 6.
      Fig 5
      Fig 5Lung point. The presence of lung point, defined as the appearance and disappearance of lung sliding with respiration at a particular point, is characteristic and pathognomonic for pneumothorax.
      Fig 6
      Fig 6Algorithm aiding the diagnosis and exclusion of pneumothorax using lung ultrasound (LUS). PTX, pneumothorax.
      The posterior lateral alveolar pleural syndrome (PLAPS) point is the lowest point in the lung that should be investigated with a curvilinear probe to rule out pleural effusion and consolidation.
      • Lichtenstein DA
      • Meziere GA.
      Relevance of lung ultrasound in the diagnosis of acute respiratory failure: The BLUE protocol.
      The detection of PLAPS point indicates consolidation or effusion at the lung bases, while absence of PLAPS point suggests other pathology at the lung bases. Normally, the spine above the diaphragm is not visible. However, if pleural effusion is present, the spine is visible through the fluid and is referred to as "spine sign". With a normally aerated lung, the lung moves downward into the abdomen with inspiration (curtain sign). In the presence of pleural effusion, this curtain sign is absent. Dynamic air bronchograms signify consolidation, while static air bronchograms indicate atelectasis. A meta-analysis comparing the accuracy of LUS and chest X-ray (CXR) indicated that LUS had a higher pooled sensitivity (0.95; 95% CI, 0.93-0.97) and specificity (0.90; 95% CI, 0.86-0.94) with better diagnostic accuracy compared to CXR in aiding the diagnosis of community-acquired pneumonia (using chest-computed tomography as the gold standard).
      • Ye X
      • Xiao H
      • Chen B
      • et al.
      Accuracy of lung ultrasonography versus chest radiography for the diagnosis of adult community-acquired pneumonia: Review of the literature and meta-analysis.

      LUS Versus Other Imaging Modalities

      LUS offers unique advantages over computed tomography, as it is portable, reproducible, low cost, low risk, and highly accurate, and possesses no radiation effects. As previously described, LUS can be used to diagnose PTX, with better sensitivity and specificity compared to CXR.
      • Ebrahimi A
      • Yousefifard M
      • Kazemi HM
      • et al.
      Diagnostic accuracy of chest ultrasonography versus chest radiography for identification of pneumothorax: A systematic review and meta-analysis.
      A meta-analysis by Ding et al. indicated that LUS had a higher pooled sensitivity (0.88) compared to CXR (0.52), and similar specificity, in the diagnosis of PTX.
      • Ding W
      • Shen Y
      • Yang J
      • et al.
      Diagnosis of pneumothorax by radiography and ultrasonography: A meta-analysis.
      Notably, the accuracy of diagnosing PTX with LUS is associated with the skill of the operator (odds ratio, 0.21; CI, 0.05-0.96; p = 0.0455). Chan et al., in a recent Cochrane Database systematic review examining LUS versus CXR for the diagnosis of PTX in trauma patients, reported a sensitivity of 0.91 (95% CI, 0.85-0.94) and specificity of 0.99 (95% CI, 0.97-1.00) for LUS, compared to a sensitivity of 0.47 (95% CI, 0.31-0.63) for CXR.
      • Chan KK
      • Joo DA
      • McRae AD
      • et al.
      Chest ultrasonography versus supine chest radiography for diagnosis of pneumothorax in trauma patients in the emergency department.
      This review suggested the superior diagnostic accuracy of LUS versus CXR for PTX diagnosis.
      LUS also is efficacious in the diagnosis of pulmonary edema.
      • Maw AM
      • Hassanin A
      • Ho MP
      • et al.
      Diagnostic accuracy of point-of-care lung ultrasonography and chest radiography in adults with symptoms suggestive of acute decompensated heart failure: A systematic review and meta-analysis.
      Maw et al. established that LUS is more sensitive (0.88 [95% CI, 0.75-0.95]) than CXR (0.73 [95% CI, 0.70-0.76]) in the detection of pulmonary edema in patients with decompensated heart failure. The relative sensitivity ratio of LUS compared to CXR was 1.2 (95% CI, 1.08-1.34; p < 0.001), proposing LUS as a useful adjunct modality in the evaluation of patients with heart failure.
      • Maw AM
      • Hassanin A
      • Ho MP
      • et al.
      Diagnostic accuracy of point-of-care lung ultrasonography and chest radiography in adults with symptoms suggestive of acute decompensated heart failure: A systematic review and meta-analysis.
      A meta-analysis by Al Deeb et al. demonstrated the sensitivity of LUS B lines to diagnose pulmonary edema as 94.1% (95% CI, 81.3-98.3), with a specificity of 92.4% (95% CI, 84.2-96.4%).
      • Al Deeb M
      • Barbic S
      • Featherstone R
      • et al.
      Point-of-care ultrasonography for the diagnosis of acute cardiogenic pulmonary edema in patients presenting with acute dyspnea: A systematic review and meta-analysis.
      Similarly, Platz et al. demonstrated the utility of B lines with LUS for prognostic purposes of heart failure therapy.
      • Platz E
      • Merz AA
      • Jhund PS
      • et al.
      Dynamic changes and prognostic value of pulmonary congestion by lung ultrasound in acute and chronic heart failure: A systematic review.
      LUS is efficacious in the diagnosis of lung parenchymal diseases,
      • Ye X
      • Xiao H
      • Chen B
      • et al.
      Accuracy of lung ultrasonography versus chest radiography for the diagnosis of adult community-acquired pneumonia: Review of the literature and meta-analysis.
      while enabling a better understanding of heart-lung interactions to assist in ventilatory management.
      • Ohman J
      • Harjola VP
      • Karjalainen P
      • et al.
      Assessment of early treatment response by rapid cardiothoracic ultrasound in acute heart failure: Cardiac filling pressures, pulmonary congestion and mortality.
      • Martindale JL
      • Wakai A
      • Collins SP
      • et al.
      Diagnosing acute heart failure in the emergency department: A systematic review and meta-analysis.
      • Dransart-Raye O
      • Roldi E
      • Zieleskiewicz L
      • et al.
      Lung ultrasound for early diagnosis of postoperative need for ventilatory support: A prospective observational study.
      • Llamas-Alvarez AM
      • Tenza-Lozano EM
      • Latour-Perez J.
      Diaphragm and lung ultrasound to predict weaning outcome: Systematic review and meta-analysis.
      LUS also can be used for confirmation of double-lumen tube placement during lung isolation maneuvers.
      • Saporito A
      • Lo Piccolo A
      • Franceschini D
      • et al.
      Thoracic ultrasound confirmation of correct lung exclusion before one-lung ventilation during thoracic surgery.
      ,
      • Parab SY
      • Kumar P
      • Divatia JV
      • et al.
      A prospective randomized controlled double-blind study comparing auscultation and lung ultrasonography in the assessment of double lumen tube position in elective thoracic surgeries involving one lung ventilation at a tertiary care cancer institute.
      Lichtenstein et al. incorporated LUS into their bedside lung ultrasound in emergency (BLUE) protocol for the diagnosis of acute respiratory failure,
      • Lichtenstein DA
      • Meziere GA.
      Relevance of lung ultrasound in the diagnosis of acute respiratory failure: The BLUE protocol.
      ,
      • Lichtenstein DA.
      BLUE-protocol and FALLS-protocol: 2 applications of lung ultrasound in the critically ill.
      and FALLS (fluid administration limited by LUS) protocol for the management of acute circulatory failure.
      • Lichtenstein DA.
      BLUE-protocol and FALLS-protocol: 2 applications of lung ultrasound in the critically ill.
      ,
      • Lichtenstein D.
      FALLS-protocol: Lung ultrasound in hemodynamic assessment of shock.
      Table 5 highlights the diagnostic utility of LUS signs, along with focused cardiac ultrasound, to help differentiate various lung diseases.
      Table 5Diagnosis of Lung Disease Based on Lung Ultrasound (LUS)
      DiagnosisPresent on LUSAbsent on LUSFOCUS
      PTXLung point

      Barcode or stratosphere sign (M mode LUS)
      Lung sliding, B lines, Lung pulse
      PNAB lines, air bronchograms, PLAPSLung sliding
      CHFBilateral B lines, lung slidingReduced FS, EF, and EPSS
      ARDSB lines, lung slidingNormal EF and EPSS
      Pulmonary fibrosisB linesLung sliding
      COPD/asthmaLung sliding, A linesB lines, PLAPS
      Pleural effusionAnechoic lung base, air bronchograms, spine signCurtain signReduced EF in CHF
      Pulmonary embolismLung sliding, A linesReduced TAPSE, reduced RV function,
      Diaphragmatic paresisReduced diaphragm excursion and thickness
      Abbreviations: ARDS, acute respiratory distress syndrome; CHF, congestive heart failure; COPD, chronic obstructive pulmonary disease; EF, ejection fraction; EPSS, endpoint (mitral) septal separation; FOCUS, Focused Cardiac Ultrasound; FS, fractional shortening; LUS, lung ultrasound; PLAPS, posterior lateral alveolar pleural syndrome; PNA, pneumonia; PTX, pneumothorax; RV, right ventricle; TAPSE, tricuspid annular plane systolic excursion.

      Diaphragm Ultrasound (DUS)

      The diaphragm is the core muscle of respiration, innervated by the phrenic nerve and normally descending caudally and increasing in thickness with inspiration. In cases of respiratory distress, LUS, along with DUS assessment, are useful to rule out potential etiologies such as PTX and diaphragmatic paralysis (ie, post-brachial plexus blockade). Diaphragmatic excursion during deep breathing (normally 6-7 cm) typically is assessed by Doppler M-mode, but may be challenging at times on the left side due to air in the stomach. A novel intercostal approach that assesses the zone of apposition of the diaphragm can be used to overcome this issue (see Fig 7). The intercostal zone of apposition approach is used to measure diaphragm thickness during inspiration and expiration. The thickening fraction then is calculated, which can be used to quantify the degree of paresis.
      • Tsui JJ
      • Tsui BC.
      A novel systematic ABC approach to Diaphragmatic Evaluation (ABCDE).
      This thickening fraction is useful for ventilatory management and in guiding the process of weaning ventilatory support in critically ill patients (normal thickening fraction is 30%-96%). DUS possesses utility in the prediction of extubation success by monitoring respiratory load, with optimal cutoffs greater than 30% to 36% for thickening fraction, serving as a beneficial tool in detecting diaphragmatic dysfunction.
      • Zambon M
      • Greco M
      • Bocchino S
      • et al.
      Assessment of diaphragmatic dysfunction in the critically ill patient with ultrasound: A systematic review.
      Fig 7
      Fig 7Panel A depicts a supine patient position with the ultrasound (US) probe placed along the midaxillary line. Panel B shows a US image of the diaphragm during inspiration (measuring diaphragm thickness of 0.25 cm).

      Focused Cardiac Ultrasound (FOCUS)

      In hemodynamically unstable patients, a focused transthoracic echocardiographic (TTE) examination (FOCUS) is useful to evaluate global and regional left and right ventricular function, assess for valvular dysfunction, and identify the presence of any hemodynamically significant pericardial effusions.
      • Cowie BS.
      Focused transthoracic echocardiography in the perioperative period.
      Specific cardiac pathology easily recognized with a FOCUS examination includes aortic stenosis (see Video 4), dilated cardiomyopathy (see Video 5), pericardial tamponade (see Video 6), hypertrophic obstructive cardiomyopathy with dynamic left ventricular outflow tract obstruction (see Video 7), endocarditis (see Video 8), and pulmonary embolism (see Video 9). Practice advisory guidelines for the appropriate use of bedside cardiac ultrasonography in the evaluation of critically ill patients, as well as grading recommendations regarding FOCUS usage for various cardiac pathologies, chest trauma, and diseases of the great vessels, are readily available.
      • Levitov A
      • Frankel HL
      • Blaivas M
      • et al.
      Guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients–part II: Cardiac ultrasonography.
      ,
      • Barber RL
      • Fletcher SN.
      A review of echocardiography in anaesthetic and peri-operative practice. Part 1: Impact and utility.
      FOCUS most commonly is performed with a low-frequency cardiac phased-array probe, with patients typically placed in supine or left lateral position to best optimize imaging and acoustic windows.
      • Coker BJ
      • Zimmerman JM.
      Why anesthesiologists must incorporate focused cardiac ultrasound into daily practice.
      ,
      • Haskins SC
      • Tanaka CY
      • Boublik J
      • et al.
      Focused cardiac ultrasound for the regional anesthesiologist and pain specialist.
      Basic FOCUS views can be used for assessment of cardiac pathology (see Table 6), as well as quantitative assessments of cardiac function (see Table 7). Via et al. have published international evidence-based recommendations, delineating the nature, technique, benefits, clinical integration, education, and certification in FOCUS to offer a framework for applying FOCUS applications across different clinical settings around the world.
      • Via G
      • Hussain A
      • Wells M
      • et al.
      International evidence-based recommendations for focused cardiac ultrasound.
      Table 6Overview of Focused Cardiac Ultrasound (FOCUS)
      FOCUS ViewAssessmentClinical IndicationPathology
      PLAXLV, RV, LA, aorta

      AV and MV
      Function, valves, effusionMI, CHF, AS, HOCM
      PSAXLV, RV

      Pericardium
      Function, effusionIschemia, hypovolemia, Tamponade
      A4CRA, RV, LA, LV

      TV, MV, AV
      Function, valves, effusionPE, MI, cardiomyopathy, Tamponade, HOCM

      CHF, RVF, PHTN
      SC4CRA, RV, LA, LVFunction, valves, effusionPE, hypovolemia, Tamponade
      SC IVCIVCVolume statusHypovolemia

      Fluid overload
      SS viewAortic arch and branchesAortic lesions

      IABP
      Aortic dissection

      Coarctation of aorta
      Abbreviations: A4C, apical four-chamber; AS, aortic stenosis; AV, aortic valve; CHF, congestive heart failure; HOCM, hypertrophic obstructive cardiomyopathy; IABP, intra-aortic balloon pump; IVC, inferior vena cava; LA, let atrium; LV, left ventricle; MI, myocardial infarction; MV, mitral valve; PE, pulmonary embolism; PHTN, pulmonary hypertension; PLAX, parasternal long-axis; PSAX, parasternal short axis; RA, right atrium; RV, right ventricle; RVF, right ventricular failure; SC4C, subcostal 4-chamber; SS, suprasternal; TV, tricuspid valve.
      Table 7Advanced Modalities With Focused Cardiac Ultrasound (FOCUS)
      2DViewAbnormal ValuesDisease
      LA

      Aorta

      RV
      PLAX

      PLAX

      PLAX, PSAX, A4C, SC4C
      Increased

      Increased

      Increased
      Dilated LA

      Aortic aneurysm

      RVH, RVF, PE
      M mode
      FS and EF

      EPSS

      TAPSE

      MAPSE
      PLAX and PSAX

      PLAX

      A4C

      A4C
      Decreased

      Decreased

      Decreased

      Decreased
      CHF

      CHF

      RVF

      LVF
      Diastology
      E/A

      e’

      E/e’ (LVEDP)
      A4C

      A4C

      A4C
      Increased

      Decreased

      Increased
      Elevated LAP

      Diastolic dysfunction

      Diastolic dysfunction
      CFD/CWD/PWD
      RVSP

      LVOT VTI

      (SV, CO)

      RVOT VTI
      A4C

      PLAX, A5C



      PSAX
      Increased

      Decreased



      Decreased
      PHTN

      LVF



      RVF
      Abbreviations: A4C, apical four-chamber; A5C, apical five-chamber; CFD, color-flow Doppler; CHF, congestive heart failure; CO, cardiac output; CWD, continuous-wave Doppler; EF, ejection fraction; EPSS, endpoint septal separation; FS, fractional shortening; IVC, inferior vena cava; LA, left atrium; LAP, left atrial pressure; LV, left ventricle; LVEDP, left ventricular end-diastolic pressure; LVF, left ventricular failure; LVOT VTI, left ventricular outflow tract velocity-time integral; MAPSE, mitral annular plane systolic excursion; PE, pulmonary embolism; PHTN, pulmonary hypertension; PLAX, parasternal long-axis; PSAX, parasternal short axis; PWD, pulsed-wave Doppler; RV, right ventricle; RVF, right ventricular failure; RVH, right ventricular hypertrophy; RVOT VTI, right ventricular outflow tract velocity-time integral; RVSP, right ventricular systolic pressure; SC4C, subcostal four-chamber; SV, stroke volume; TAPSE, tricuspid annular plane systolic excursion.
      Hemodynamic perturbations and unexplained hypotension are extremely common issues encountered in the perioperative setting, with FOCUS being a useful tool for determining the etiology of unexplained hemodynamic instability, as well as for guiding clinical management and interventions. FOCUS is particularly helpful in detecting right ventricular dysfunction and regional wall motion abnormalities following ischemia in patients presenting with acute coronary syndromes.
      • Rallidis LS
      • Makavos G
      • Nihoyannopoulos P.
      Right ventricular involvement in coronary artery disease: Role of echocardiography for diagnosis and prognosis.
      ,
      • Cheitlin MD
      • Armstrong WF
      • Aurigemma GP
      • et al.
      ACC/AHA/ASE 2003 guideline update for the clinical application of echocardiography: Summary article: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/ASE Committee to Update the 1997 Guidelines for the Clinical Application of Echocardiography).
      When FOCUS is used to answer a specific clinical question (eg, investigation of newly discovered systolic murmur or to determine the underlying etiology of unexplained hemodynamic instability or decreased functional capacity), its use has a significant impact on perioperative care (eg, altered anesthetic technique, prompted decision to perform invasive monitoring, or led to a change postoperative care disposition) in up to 82% of patients.
      • Cowie B.
      Three years’ experience of focused cardiovascular ultrasound in the peri-operative period.
      In the aforementioned study, major findings from anesthesiologist-performed FOCUS examinations (ie, significant valvular lesions) were confirmed subsequently by cardiology evaluation in 92% of patients. Massive pulmonary embolism and cardiac tamponade are potentially devasting perioperative complications in which FOCUS provides rapid diagnostic confirmation to guide immediate lifesaving treatments. Valvular stenosis, valvular regurgitation, left and right ventricular dysfunction, cardiac masses, and cardiomyopathies (ie, hypertrophic cardiomyopathy, dilated cardiomyopathy) can be assessed quickly and, where relevant, quantified with a FOCUS examination.
      • Luong CL
      • Ong K
      • Kaila K
      • et al.
      Focused cardiac ultrasonography: Current applications and future directions.
      FOCUS also is emerging as a valuable tool in the diagnosis and management of cardiac arrest. The Focused Echocardiographic Examination in Life protocol describes FOCUS usage during performance of advanced cardiac life support (ACLS) protocols.
      • Price S
      • Uddin S
      • Quinn T.
      Echocardiography in cardiac arrest.
      ,
      • Breitkreutz R
      • Price S
      • Steiger HV
      • et al.
      Focused echocardiographic evaluation in life support and peri-resuscitation of emergency patients: A prospective trial.
      Importantly, FOCUS can be incorporated into the performance of ACLS without interrupting performance of standard chest compressions, with subcostal views best facilitating this indication. Adequate images may be obtained during brief (ie, ten-second) periods when compressions are interrupted to assess for underlying cardiac rhythm and pulse. The presence of underlying cardiac activity by FOCUS assessment during ACLS has been associated with improved survival following return of spontaneous circulation.
      • Kedan I
      • Ciozda W
      • Palatinus JA
      • et al.
      Prognostic value of point-of-care ultrasound during cardiac arrest: A systematic review.
      The use of FOCUS in this setting also enables clinicians to diagnose potentially treatable and reversible causes (eg, pulmonary embolism, tamponade, or severe left ventricular dysfunction) and to guide further therapeutic interventions.

      Vascular Ultrasound (VUS)

      VUS (see Table 8) with a linear probe commonly is used for the placement of central venous, arterial, and peripheral intravenous catheters. Furthermore, FOCUS examination aids in assessing volume status, as central venous pressure or right atrial pressure estimations (performed using the subcostal inferior vena cava [IVC] view), can be obtained by measuring IVC diameter, respiratory variation, and collapsibility index.
      • Gui J
      • Yang Z
      • Ou B
      • et al.
      Is the collapsibility index of the inferior vena cava an accurate predictor for the early detection of intravascular volume change?.
      A meta-analysis evaluating the utility of using measurements of IVC diameter and respiratory variation to predict fluid responsiveness found the modality more sensitive and specific in mechanically ventilated patients compared to spontaneously breathing patients.
      • Long E
      • Oakley E
      • Duke T
      • et al.
      Does respiratory variation in inferior vena cava diameter predict fluid responsiveness: A systematic review and meta-analysis.
      Other modalities, such as carotid Doppler, can be used for hemodynamic assessments.
      • Barjaktarevic I
      • Toppen WE
      • Hu S
      • et al.
      Ultrasound assessment of the change in carotid corrected flow time in fluid responsiveness in undifferentiated shock.
      ,
      • Sidor M
      • Premachandra L
      • Hanna B
      • et al.
      Carotid flow as a surrogate for cardiac output measurement in hemodynamically stable participants.
      Using POCUS to assess change in carotid flow time is an acceptable method for noninvasive assessment of fluid responsiveness in shock states, and also can act as a surrogate for cardiac output.
      Table 8Vascular Ultrasound Applications
      ModalityStructuresProcedures/Assessments
      Vascular accessIJ, subclavian, and femoral veins

      Radial, brachial, and femoral arteries

      Peripheral veins
      Central lines

      Arterial lines

      PIVs
      Volume assessmentIVC

      Common carotid artery

      Common femoral vein
      CVP, RAP

      CFT, carotid VTI

      Pulsatility (RV function)
      VExUSIVC (transverse view)

      Hepatic vein

      Portal vein

      Renal vein
      VExUS score for fluid overload
      Venous scanLower extremity veinsDVT
      Abbreviations: CFT, corrected flow time; CVP, central venous pressure; DVT, deep vein thrombosis; IJ, internal jugular; IVC, inferior vena cava; PIVs, peripheral intravenous lines; RAP, right atrial pressure; RV, right ventricle; VExUS scan, venous excess ultrasound scan; VTI, velocity-time integral.
      If the IVC transverse diameter is more than 2 cm, the use of combined hepatic vein, portal vein, and renal vein pulsed-wave Doppler assessments, as a part of venous excess ultrasound (VExUS) scan, can be done to evaluate for volume overload and systemic venous congestion. Beaubien-Souligny et al. described a VExUS scoring system (see Table 9) to quantify systemic congestion and its impact on renal dysfunction in post-cardiac surgery patients.
      • Beaubien-Souligny W
      • Rola P
      • Haycock K
      • et al.
      Quantifying systemic congestion with point-of-care ultrasound: Development of the venous excess ultrasound grading system.
      • Beaubien-Souligny W
      • Benkreira A
      • Robillard P
      • et al.
      Alterations in portal vein flow and intrarenal venous flow are associated with acute kidney injury after cardiac surgery: A prospective observational cohort study.
      • Beaubien-Souligny W
      • Eljaiek R
      • Fortier A
      • et al.
      The association between pulsatile portal flow and acute kidney injury after cardiac surgery: A retrospective cohort study.
      The severity of the VExUS score is used as a guide for fluids, inotropes, vasodilators, and diuretic management. Measurement of the right ventricular outflow tract velocity-time integral with FOCUS, when combined with the VExUS scan, enables a global evaluation of right ventricular function and, when dysfunction is present, its effects on systemic organ congestion.
      Table 9Simplified Venous Excess Ultrasound (VExUS) Scoring System
      Organ systemVExUS = 0

      (No Congestion)
      VExUS = 1VExUS = 2VExUS = 3

      (Severe Congestion)
      IVCIVC < 2 cmIVC > 2 cmIVC > 2 cmIVC > 2 cm
      Hepatic vein

      Doppler
      Normal patternNormal

      (S > D)
      Mild abnormality

      (S < D)
      Severe abnormality

      (S wave reversal)
      Portal vein

      Doppler
      Normal patternNormal

      (<30% pulsatility index)
      Mild abnormality

      (30%-49% pulsatility index)
      Severe abnormality

      (>50% pulsatility index)
      Renal vein

      Doppler
      Normal patternNormal

      (continuous monophasic flow)
      Mild abnormality

      (discontinuous biphasic flow)
      Severe abnormality

      (discontinuous monophasic flow)
      NOTE. Adapted from: Beaubien-Souligny et al.
      • Beaubien-Souligny W
      • Rola P
      • Haycock K
      • et al.
      Quantifying systemic congestion with point-of-care ultrasound: Development of the venous excess ultrasound grading system.
      Abbreviations: D, diastolic wave; IVC, inferior vena cava; S, systolic wave; VExUS, Venous Excess Ultrasound Score.
      Additionally, evaluation for the presence of lower-extremity deep vein thrombosis (DVT) is a core part of the POCUS examination, especially in critically ill patients. A comprehensive scan should begin with visualization of the common femoral vein. Subsequently, all five major points of vascular bifurcation within the lower-extremity veins are identified, with a two-point compression test performed at each point to rule out DVT.
      • Bhatt M
      • Braun C
      • Patel P
      • et al.
      Diagnosis of deep vein thrombosis of the lower extremity: A systematic review and meta-analysis of test accuracy.
      ,
      • Needleman L
      • Cronan JJ
      • Lilly MP
      • et al.
      Ultrasound for lower extremity deep venous thrombosis. Multidisciplinary recommendations from the Society of Radiologists in Ultrasound Consensus Conference.
      A systematic review assessing the accuracy of emergency physician-performed ultrasound found a sensitivity of 96.1% and specificity of 96.8% for the diagnosis of DVT.
      • Pomero F
      • Dentali F
      • Borretta V
      • et al.
      Accuracy of emergency physician-performed ultrasonography in the diagnosis of deep-vein thrombosis: A systematic review and meta-analysis.
      Also, positive findings from the VUS DVT scan, when accompanied with FOCUS assessment of RV function (along with focused LUS), can be helpful in ruling out pulmonary embolism.
      • Khemasuwan D
      • Yingchoncharoen T
      • Tunsupon P
      • et al.
      Right ventricular echocardiographic parameters are associated with mortality after acute pulmonary embolism.
      • Fields JM
      • Davis J
      • Girson L
      • et al.
      Transthoracic echocardiography for diagnosing pulmonary embolism: A systematic review and meta-analysis.
      • Squizzato A
      • Rancan E
      • Dentali F
      • et al.
      Diagnostic accuracy of lung ultrasound for pulmonary embolism: A systematic review and meta-analysis.

      Regional Anesthesia

      Interfascial plane blocks play an emerging role in perioperative pain management.
      • Kelava M
      • Alfirevic A
      • Bustamante S
      • et al.
      Regional anesthesia in cardiac surgery: An overview of fascial plane chest wall blocks.
      Due to the risks associated with epidural and paravertebral techniques, interfascial plane blocks (see Table 10) are a safer alternative for patients after cardiac surgery and can be incorporated readily into a multimodal pain management plan for a number of cardiac, thoracic, and vascular procedures, due to their relative ease of performance and low level of complications.
      • De Cosmo G
      • Aceto P
      • Gualtieri E
      • et al.
      Analgesia in thoracic surgery: Review.
      ,
      • Mittnacht AJC
      • Shariat A
      • Weiner MM
      • et al.
      Regional techniques for cardiac and cardiac-related procedures.
      The implementation of these blocks into multimodal cardiac enhanced recovery pathways helps to minimize opioid consumption, reduce nausea and vomiting, reduce postoperative ventilatory time, improve patient satisfaction, and provide cost reductions.
      • Ljungqvist O
      • Scott M
      • Fearon KC.
      Enhanced recovery after surgery: A review.
      ,
      • Williams JB
      • McConnell G
      • Allender JE
      • et al.
      One-year results from the first US-based enhanced recovery after cardiac surgery (ERAS Cardiac) program.
      Involvement of the cardiothoracic anesthesiologist with these regional techniques has the additional benefit of providing further experience in performing LUS, as these interfascial plane blocks are performed on the chest. In particular, it is important to be facile in recognizing the presence of pneumothorax, which is a complication associated with paravertebral blocks. Many centers use paravertebral blocks for pain control after thoracotomy, with these novel interfascial plane blocks playing an important role in enhanced recovery pathways for cardiac and thoracic surgeries. Nagaraja et al., in a comparison of thoracic epidural analgesia versus bilateral erector spinae plane (ESP) blocks for cardiac surgical procedures, revealed comparable pain scores until 12 hours postoperatively, along with similar ventilator days and ICU duration of stay, suggesting ESP block as a viable alternative to thoracic epidural analgesia.
      • Nagaraja PS
      • Ragavendran S
      • Singh NG
      • et al.
      Comparison of continuous thoracic epidural analgesia with bilateral erector spinae plane block for perioperative pain management in cardiac surgery.
      In a second patient-matched controlled study, continuous ESP block was associated with decreased opioid consumption and earlier mobilization after open cardiac surgery.
      • Macaire P
      • Ho N
      • Nguyen T
      • et al.
      Ultrasound-guided continuous thoracic erector spinae plane block within an enhanced recovery program is associated with decreased opioid consumption and improved patient postoperative rehabilitation after open cardiac surgery–A patient-matched, controlled before-and-after study.
      In a randomized controlled trial comparing serratus anterior plane block with thoracic epidural analgesia for thoracotomy, Khalil et al. found comparable pain scores and opioid consumption in both groups, without a significant drop in mean arterial blood pressure compared to baseline values in the serratus block group, suggesting serratus plane block is a safe and effective alternative for postoperative analgesia in thoracotomy.
      • Khalil AE
      • Abdallah NM
      • Bashandy GM
      • et al.
      Ultrasound-guided serratus anterior plane block versus thoracic epidural analgesia for thoracotomy pain.
      Table 10Ultrasound-Guided Regional Anesthesia Applications for the Cardiothoracic Anesthesiologist
      RegionalSite of Injection of Local AnestheticSurgical Procedures
      PECS I and II blocksBetween PMaM and PMiM and between PMiM and SAMICD, pacemaker insertion

      Right anterior thoracotomy
      SAPBBetween the rib and SAM or between SAM and LDMThoracotomy, VATS,

      Rib fracture

      Minimally invasive cardiac surgery
      ESPBBetween the TP and ESMThoracotomy, VATS

      Rib fracture

      Sternotomy
      PIFB/TTPBBetween PMaM and EIM/between IIM and TTMSternotomy,

      sternal fracture
      Abbreviations: EIM, external intercostal muscle; ESM, erector spinae muscle; ESPB, erector spinae plane block; ICD, implantable cardioverter-defibrillator; IIM, internal intercostal muscle; LDM, latissimus dorsi muscle; PECS block, pectoral nerve block; PIFB, pecto-intercostal fascial block; PMaM, pec major muscle; PMiM, pec minor muscle; SAM, serratus anterior muscle; SAPB, serratus anterior plane block; TP, transverse process; TTM, transversus thoracic muscle; TTPB, transversus thoracis plane block; VATS, video-assisted thoracoscopic surgery

      Focused Assessment With Sonography in Trauma (FAST)

      FAST is a commonly used diagnostic modality in trauma patients to evaluate for intrabdominal fluid, as well as to guide surgical interventions.
      • Manson WC
      • Kirksey M
      • Boublik J
      • et al.
      Focused assessment with sonography in trauma (FAST) for the regional anesthesiologist and pain specialist.
      ,
      • Montoya J
      • Stawicki SP
      • Evans DC
      • et al.
      From FAST to E-FAST: An overview of the evolution of ultrasound-based traumatic injury assessment.
      In the postoperative setting, FAST can be used rapidly to assess for intra-abdominal fluid collections in the workup for hypotension.
      • Sisley AC
      • Rozycki GS
      • Ballard RB
      • et al.
      Rapid detection of traumatic effusion using surgeon-performed ultrasonography.
      The FAST examination (see Table 11) can be performed easily at the bedside and repeated according to the clinical context to guide continued clinical management. In a Cochrane review on the evaluation of POCUS for diagnosing thoracoabdominal injuries in blunt trauma, positive findings, such as free fluid in thoracic or abdominal cavities, major solid organ injuries, or lesions of major vessels, were found to help regarding guiding management decision, with a sensitivity of 0.68 and specificity of 0.95 for abdominal trauma.
      • Stengel D
      • Leisterer J
      • Ferrada P
      • et al.
      Point-of-care ultrasonography for diagnosing thoracoabdominal injuries in patients with blunt trauma.
      The Rapid Ultrasound for Shock and Hypotension protocol is useful in patients with undifferentiated shock, incorporating POCUS of the heart, IVC, Morison's pouch, aorta, and pneumothorax to identify rapidly reversible causes of hypotension.
      • Perera P
      • Mailhot T
      • Riley D
      • et al.
      The RUSH exam: Rapid Ultrasound in SHock in the evaluation of the critically lll.
      Table 11Focused Assessment With Sonography in Trauma (FAST)
      FAST ViewStructuresPositive Signs
      RUQLiver, right kidney, hepatorenal pouch, diaphragm, right lungMorison's pouch +, inferior pole of liver +
      LUQSpleen, left kidney, splenorenal recess, diaphragm, left lungSplenorenal pouch +, subphrenic space +
      Pelvic sagittal and transverseBladder, rectum, uterus (in women)Rectovesical pouch + (men)

      Pouch of Douglas + (women)
      Extended FAST

      (e-FAST)
      Lungs (LUS)

      Cardiac (SC4C)
      Pneumothorax

      Hemothorax

      Tamponade
      Abbreviations: +, blood present; LUQ, left upper quadrant; LUS, lung ultrasound; RUQ, right upper quadrant; SC4C, subcostal four-chamber view.

      POCUS in the Critical Care Setting

      POCUS use in the critical care setting has burgeoned over the past decades, with the core competencies of POCUS now widely viewed as mandatory skill sets required by the modern critical care medicine clinician.
      • Blans MJ
      • Bosch FH
      • van der Hoeven JG.
      A practical approach to critical care ultrasound.
      In the following, various applications of POCUS in the ICU are addressed, including ICU-specific echocardiography, LUS, abdominal ultrasound, and vascular ultrasound.
      Echocardiography, both TTE and TEE, long have been used in the ICU. The causes of ICU-related hemodynamic instability are diverse and include, but are not limited to, ventricular dysfunction, myocardial ischemia, arrhythmias, sepsis, acute blood loss, cardiac tamponade, and respiratory failure.
      • Stephens RS
      • Whitman GJ.
      Postoperative critical care of the adult cardiac surgical patient. Part I: Routine postoperative care.
      Multiple examples exist within the literature demonstrating the value of POCUS for diagnosing etiologies of hemodynamic instability.
      • Perera P
      • Mailhot T
      • Riley D
      • et al.
      The RUSH exam: Rapid Ultrasound in SHock in the evaluation of the critically lll.
      ,
      • Atkinson PRT
      • McAuley DJ
      • Kendall RJ
      • et al.
      Abdominal and Cardiac Evaluation with Sonography in Shock (ACES): An approach by emergency physicians for the use of ultrasound in patients with undifferentiated hypotension.
      The utility of TTE and TEE for the management of hemodynamically unstable cardiac and patients after noncardiac surgery has been shown to result in the determination of definitive diagnosis and subsequent change in clinical management in 58.8% of patients in this context.
      • Markin NW
      • Gmelch BS
      • Griffee MJ
      • et al.
      A review of 364 perioperative rescue echocardiograms: Findings of an anesthesiologist-staffed perioperative echocardiography service.
      Patients in the ICU benefiting from the use of POCUS also include those requiring mechanical circulatory support devices. Lu et al. demonstrated that trained intensivists can perform adequate bedside TTE, TEE, and FAST examinations on patients with mechanical circulatory support to guide medical and surgical management.
      • Lu SY
      • Dalia AA
      • Cudemus G
      • et al.
      Rescue echocardiography/ultrasonography in the management of combined cardiac surgical and medical patients in a cardiac intensive care unit.
      In their study, 189 rescue POCUS examinations were performed in a mixed cardiac medical/surgical ICU, of which 4% led to extracorporeal membrane oxygenation or ventricular assist device cannula reposition, 2% lead to extracorporeal membrane oxygenation or ventricular assist device setting change, and 1% led to right ventricular assist device insertion.
      In addition, POCUS has utility in the evaluation of fluid responsiveness and to help guide appropriate fluid resuscitation. When combined with LUS, echocardiography (specifically IVC imaging) can aid in fluid resuscitation management in the critically ill, as demonstrated by Lee et al.
      • Lee CW
      • Kory PD
      • Arntfield RT.
      Development of a fluid resuscitation protocol using inferior vena cava and lung ultrasound.
      By combining current literature on lung and IVC ultrasound with expert opinion on the ability of transthoracic ultrasound to predict fluid responsiveness, investigators were able to develop a qualitative fluid resuscitation guide that categorized critically ill patients into one of three broad groups: fluid resuscitate, fluid test, and fluid restrict. Validation of this resuscitation guide to help clinicians prescribe fluid therapy still is pending.
      LUS is helpful in the evaluation of respiratory failure and can diagnose acutely and guide treatment for a wide range of lung pathologies, including pulmonary edema, pleural effusion, pneumonia, and PTX.
      • Lichtenstein DA
      • Meziere GA.
      Relevance of lung ultrasound in the diagnosis of acute respiratory failure: The BLUE protocol.
      The FALLS protocol uses elements of the BLUE protocol, in combination with basic echocardiography, to rule out other causes of shock (obstructive, cardiogenic, and hypovolemic) while highlighting an endpoint of resuscitation for distributive shock (the transition on lung ultrasound from an A-profile to a B-profile).
      In addition, LUS can aid in identifying the need for postoperative ventilatory support, as established by Dransart-Raye et al.
      • Dransart-Raye O
      • Roldi E
      • Zieleskiewicz L
      • et al.
      Lung ultrasound for early diagnosis of postoperative need for ventilatory support: A prospective observational study.
      In this study, the presence of two areas of consolidated lung was associated with a lower PaO2 per FIO2 ratio, the need for postoperative ventilatory support, longer intensive care stays, and episodes of ventilator-associated pneumonia requiring antibiotics. In summary, LUS has the ability to diagnosis acutely and accurately the causes of respiratory failure, aid in volume resuscitation, identify patients likely to need postoperative ventilatory support, and assist in weaning mechanical ventilation.
      Abdominal POCUS long has been used in emergency medicine; has a reported sensitivity, specificity, and accuracy of bedside sonography in identifying intraperitoneal hemorrhage of 81.8%, 93.9%, and 90.9%, respectively; and is able be performed in less than a minute in most ICU patients.
      • Jehle D
      • Guarino J
      • Karamanoukian H.
      Emergency department ultrasound in the evaluation of blunt abdominal trauma.
      The initial abdominal ultrasound protocol (FAST examination) has been updated to the extended FAST examination (e-FAST), which incorporates LUS for the assessment of PTX and was found to have sensitivities and specificities superior to those of CXR.
      • Alrajab S
      • Youssef AM
      • Akkus NI
      • et al.
      Pleural ultrasonography versus chest radiography for the diagnosis of pneumothorax: Review of the literature and meta-analysis.
      FAST and e-FAST examinations are unique in their ability to allow the intensivist to evaluate fresh postoperative cardiac surgery patients experiencing hypotension for abdominal or thoracic hemorrhage. Abdominal ultrasound also has been used to measure abdominal aortic aneurysm diameter and to diagnose aneurysm rupture.
      • Rubano E
      • Mehta N
      • Caputo W
      • et al.
      Systematic review: Emergency department bedside ultrasonography for diagnosing suspected abdominal aortic aneurysm.
      In addition, bedside abdominal ultrasound can be used to evaluate, quantify, and guide paracentesis for abdominal ascites.
      • Frankel HL
      • Kirkpatrick AW
      • Elbarbary M
      • et al.
      Guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients–part I: General ultrasonography.
      POCUS also has been used to diagnose obstructive nephropathy,
      • Frankel HL
      • Kirkpatrick AW
      • Elbarbary M
      • et al.
      Guidelines for the appropriate use of bedside general and cardiac ultrasonography in the evaluation of critically ill patients–part I: General ultrasonography.
      hydronephrosis,
      • Pathan SA
      • Mitra B
      • Mirza S
      • et al.
      Emergency physician interpretation of point-of-care ultrasound for identifying and grading of hydronephrosis in renal colic compared with consensus interpretation by emergency radiologists.
      nephrolithiasis,
      • Gaspari RJ
      • Horst K.
      Emergency ultrasound and urinalysis in the evaluation of flank pain.
      and bladder distention,
      • Byun SS
      • Kim HH
      • Lee E
      • et al.
      Accuracy of bladder volume determinations by ultrasonography: Are they accurate over entire bladder volume range?.
      as well as assisting in difficult Foley catheter placement.
      • Joseph R
      • Huber M
      • Leeson B
      • et al.
      Ultrasound-guided placement of a Foley catheter using a hydrophilic guide wire.
      All of these attributes make abdominal ultrasound ideally suited for routine use in the ICU.
      The use of vascular ultrasound in the ICU ranges from vascular access (central venous access, arterial access, and peripheral venous access) to the diagnosis of DVT. Central venous access has been an accepted application of POCUS for a long period of time, as demonstrated by multiple studies in the literature, dating back to the early 1990s.
      • Soni NJ
      • Reyes LF
      • Keyt H
      • et al.
      Use of ultrasound guidance for central venous catheterization: A national survey of intensivists and hospitalists.
      • Parienti JJ
      • Mongardon N
      • Megarbane B
      • et al.
      Intravascular complications of central venous catheterization by insertion site.
      • Maizel J
      • Bastide MA
      • Richecoeur J
      • et al.
      Practice of ultrasound-guided central venous catheter technique by the French intensivists: A survey from the BoReal study group.
      • Wong AV
      • Arora N
      • Olusanya O
      • et al.
      Insertion rates and complications of central lines in the UK population: A pilot study.
      The benefits of vascular ultrasound for central venous access include identification of appropriate vessels for cannulation, identification of aberrant vascular anatomy, verification of vessel patency, and real-time confirmation of correct device placement,
      • Schmidt GA
      • Blaivas M
      • Conrad SA
      • et al.
      Ultrasound-guided vascular access in critical illness.
      as well as higher first attempt success rates and lower mechanical complication rates.
      • Brass P
      • Hellmich M
      • Kolodziej L
      • et al.
      Ultrasound guidance versus anatomical landmarks for internal jugular vein catheterization.
      These benefits are associated most strongly with internal jugular vein access, while being associated less strongly with subclavian and femoral vein access.
      • Brass P
      • Hellmich M
      • Kolodziej L
      • et al.
      Ultrasound guidance versus anatomical landmarks for internal jugular vein catheterization.
      POCUS also has been demonstrated to be superior to traditional blind cannulation techniques for both peripheral IVs and arterial lines regarding success rate, time to cannulation, and number of skin punctures.
      • McCarthy ML
      • Shokoohi H
      • Boniface KS
      • et al.
      Ultrasonography versus landmark for peripheral intravenous cannulation: A randomized controlled trial.
      • Bauman M
      • Braude D
      • Crandall C.
      Ultrasound-guidance vs. standard technique in difficult vascular access patients by ED technicians.
      • White L
      • Halpin A
      • Turner M
      • et al.
      Ultrasound-guided radial artery cannulation in adult and paediatric populations: A systematic review and meta-analysis.
      • Sobolev M
      • Slovut DP
      • Chang AL
      • et al.
      Ultrasound-guided catheterization of the femoral artery: A systematic review and meta-analysis of randomized controlled trials.
      Another useful application of vascular ultrasound in the ICU is the detection of DVT. One study demonstrated that proximal lower-extremity DVT diagnosed by POCUS had an 86% sensitivity and 96% specificity compared to formal ultrasound studies.
      • Kory PD
      • Pellecchia CM
      • Shiloh AL
      • et al.
      Accuracy of ultrasonography performed by critical care physicians for the diagnosis of DVT.
      POCUS allows for the early detection and timely intervention in thromboembolic disease processes seen in the ICU.

      Limitations of POCUS

      It is critical to understand the limitations of each POCUS application in clinical practice. Identification of an appropriate POCUS indication based on clinical presentation and knowledge of the pre-test probability are the first steps for successful POCUS usage. Understanding the sensitivity and specificity of each POCUS application, in comparison to other standard techniques, plays a key role in the successful application of POCUS for diagnostic purposes. Both individual patient factors and operator experience should be taken into consideration. The complete clinical context of the patient should be taken into account rather than simply treating the images obtained. It is advisable to seek expert help and archive images in situations of especially challenging POCUS diagnoses to ensure safe patient care and avoid errors in clinical management. Adequate training, as well as adherence to established competencies and credentialing, are essential.

      POCUS Education and Certification

      Ultrasound use has become ever more ubiquitous across a variety of medical disciplines, and ultrasound education is now part of the core curriculum of multiple medical schools.
      • Feilchenfeld Z
      • Dornan T
      • Whitehead C
      • et al.
      Ultrasound in undergraduate medical education: A systematic and critical review.
      A four-component rationale for incorporating ultrasound education into medical education has been proposed by education leaders in the California medical school system, positing that ultrasound education (1) enhances traditional medical education, (2) improves the diagnostic and procedural skill set of trainees, (3) promotes more efficient patient care, and (4) serves as a basis for more advanced and specialty-specific ultrasound training during residency training and beyond.
      • Chiem AT
      • Soucy Z
      • Dinh VA
      • et al.
      Integration of ultrasound in undergraduate medical education at the California medical schools: A discussion of common challenges and strategies from the UMeCali experience.
      In the context of anesthesiology, POCUS education includes echocardiography (transesophageal and transthoracic), procedural ultrasound for vascular access and regional anesthesia, as well as a growing variety of diagnostic uses (abdomen-chest-airway evaluation, gastric volume determination, and intracranial pressure estimation).
      • Mahmood F
      • Matyal R
      • Skubas N
      • et al.
      Perioperative ultrasound training in anesthesiology: A call to action.
      While cardiac echocardiography and ultrasound for regional anesthesia have been well-established core elements of anesthesiology residency education, as yet, no single structured POCUS curriculum or professional society guidelines have become uniform across all anesthesiology training programs.
      • Ramsingh D
      • Runyon A
      • Gatling J
      • et al.
      Improved diagnostic accuracy of pathology with the implementation of a perioperative point-of-care ultrasound service: Quality improvement initiative.
      With the introduction of novel surgical techniques two decades ago, a similar situation was faced by the American College of Surgeons (ACS), with a need to demonstrate proficiency in these laparoscopic and endoscopic surgeries. The ACS engendered the Fundamentals of Laparoscopic Surgery (FLS) and Fundamentals of Endoscopic Surgery (FES) programs, which enable the evaluation of surgical trainees’ knowledge base, technical skills, clinical judgment, and overall competency in these respective surgical areas.
      • Cullinan DR
      • Schill MR
      • DeClue A
      • et al.
      Fundamentals of laparoscopic surgery: Not only for senior residents.
      ,
      • Ritter EM
      • Taylor ZA
      • Wolf KR
      • et al.
      Simulation-based mastery learning for endoscopy using the endoscopy training system: A strategy to improve endoscopic skills and prepare for the fundamentals of endoscopic surgery (FES) manual skills exam.
      In 2019, the National Board of Echocardiography, in conjunction with 9nine medical societies, administered the first Examination of Special Competence in Critical Care Echocardiography, with successful completion leading to testamur status.

      National Board of Echocardiography. Application for certification in critical care echocardiography (CCeXAM). Available at: https://echoboards.org/docs/CCEeXAM-Cert_App-2020.pdf. Accessed January 27, 2021.

      The Examination of Special Competence in Critical Care Echocardiography content transcends cardiac-specific topics and includes content germane to a variety of POCUS topics: ultrasound physics, ultrasound technical skills, ultrasound image optimization, lung and pleura imaging, as well as focused vascular and abdominal imaging. Though significant momentum for POCUS education is occurring at the medical school and graduate medical education level, a need now exists to incorporate all of the aforementioned POCUS applications and content into both anesthesiology residency education and for those clinicians beyond training. For clinicians beyond training seeking ultrasound and POCUS training, a variety of regional and national medical societies (eg, American Society of Anesthesiologists, Society of Critical Care Medicine, American Society of Regional Anesthesia, Society of Cardiovascular Anesthesiologists), as well as independent commercial organizations (eg, POCUS Certification Academy), offer POCUS-related educational activities; additional options after training typically include self-directed learning and simulation-based training.
      • Ramsingh D
      • Runyon A
      • Gatling J
      • et al.
      Improved diagnostic accuracy of pathology with the implementation of a perioperative point-of-care ultrasound service: Quality improvement initiative.
      In a 2017 survey of a variety of 343 critical care medicine clinicians of varying backgrounds, as compared to other specialties, those clinicians with primary residency training in emergency medicine were more likely to have received POCUS training during their residency training (73.5%, p < 0.001) compared to the other surveyed specialties (8.7%). Of the nonemergency medicine specialties, including anesthesiology, POCUS training was derived from an external educational course (26.5%) or through self-guided learning (17.2%).
      • Stowell JR
      • Kessler R
      • Lewiss RE
      • et al.
      Critical care ultrasound: A national survey across specialties.
      To date, there is no literature specifically examining POCUS education in the training context versus thereafter via conferences and workshops. Hence, at present, quality assurance as to the education experience for a given clinician only may be assessed by competency evaluations, which include mandating a minimum number of reviewed POCUS scans and imaging analogous to existing echocardiography certification pathways.
      • McCormick TJ
      • Miller EC
      • Chen R
      • et al.
      Acquiring and maintaining point-of-care ultrasound (POCUS) competence for anesthesiologists.
      As growing numbers of perioperative clinicians, who already have completed training seek POCUS education, as well as the broad variety of POCUS training options outside of the formal medical education systems, the need for codifying what constitutes adequate POCUS education and competency should be prioritized.
      As POCUS continues to evolve in its diagnostic and procedural applications, there is yet to be a single unified or codified POCUS training curriculum in the United States analogous to the ACS FLS and FES programs. In a 2016 call to action, Mahmood et al. outlined three components needed for the development of a core POCUS educational program: (1) during anesthesiology residency, POCUS training should be “continuous and structured” and (2) residency programs should develop individual ultrasound education tools and means for evaluation that align with existing Accreditation Council for Graduate Medical Education milestone expectations.
      • Mahmood F
      • Matyal R
      • Skubas N
      • et al.
      Perioperative ultrasound training in anesthesiology: A call to action.
      Analogous to the aforementioned FLS and FES programs, anesthesiology residency programs also should work to develop a structured and unified approach to anesthesiology POCUS training, and (3) additional advanced POCUS concepts and skills training at the fellowship level or beyond also should be part of constructing a unified POCUS educational curriculum.
      • Mahmood F
      • Matyal R
      • Skubas N
      • et al.
      Perioperative ultrasound training in anesthesiology: A call to action.
      In addition to these three elements, other authors also highlighted that a complete POCUS educational curriculum should include maintenance of POCUS skills after training and professional development.
      • Meineri M
      • Bryson GL
      • Arellano R
      • et al.
      Core point-of-care ultrasound curriculum: What does every anesthesiologist need to know?.
      The International Federation of Emergency Medicine published a consensus document in 2015 that provided stepwise guidance for POCUS training in their domain; however, this POCUS training framework is relatively generic and applicable to anesthesiology.
      • Atkinson P
      • Bowra J
      • Lambert M
      • et al.
      International Federation for Emergency Medicine point of care ultrasound curriculum.
      Applied to POCUS education, this framework began with defining what applications (core and advanced techniques) are to be taught and how each of these applications will be taught. Regarding POCUS education methodology, a four-step process should be used: application introduction, experiential use and development (ie, documented via case log), obtaining competence (expert review of case log along with skills assessment), and maintenance of competency (continuing POCUS education and case log maintenance). In assigning levels of competency, neither the Accreditation Council for Graduate Medical Education nor any specific American anesthesiology society has yet to set standards, milestones, or required levels of training specific to POCUS.
      • McCormick TJ
      • Miller EC
      • Chen R
      • et al.
      Acquiring and maintaining point-of-care ultrasound (POCUS) competence for anesthesiologists.
      However, the American Board of Anesthesiology, as part of the Objective Structured Clinical Examination component to board certification, includes testing candidates’ interpretation of basic TEE, basic TTE, and chest ultrasound imaging, with specific POCUS applications being added to the Objective Structured Clinical Examination beginning in 2022.

      American Board of Anesthesiology. Applied exam. Objective Strutured Clinical Examination (OSCE) content outline. Available at: https://theaba.org/pdfs/OSCE_Content_Outline.pdf. 2021

      Building on the aforementioned POCUS educational framework concepts, in 2019 the American Society of Anesthesiologists convened its first Ad Hoc Committee on POCUS, which, in part, specifically addressed the minimum level of training in diagnostic POCUS needed for competence. See Table 12 for the American Society of Anesthesiologists Ad Hoc Committee's recommendations on training requirements required to be considered POCUS competent based on the 2019 Committee Work Product on Diagnostic Point-of-Care Ultrasound of the American Society of Anesthesiologists.

      Based on the 2019 Committee Work Product on Diagnostic Point-of-Care Ultrasound of the American Society of Anesthesiologists. A copy of the full text can be obtained from ASA, 1061 American Lane Schaumburg, IL 60173-4973 or online at www.asahq.org 2021

      The Association of Anaesthetists of Great Britain and Ireland and the Intensive Care Society POCUS training curriculum offer three competency levels that could be applied similarly in the United States (see Table 13).

      Association of Anaesthestists of Great Britain and Ireland, The Royal College of Anaesthetists, The Intensive Care Society. Ultrasound in anaesthesia and intensive care: A guide to training. Available at: https://anaesthetists.org/Home/Resources-publications/Guidelines/Ultrasound-in-anaesthesia-and-intensive-care-a-guide-to-training. Accessed January 27, 2021.

      Table 12Pathways for Attaining POCUS Competency
      POCUS Competency Pathways
      Supervised Training PathwayEstablished Expertise Pathway
      POCUS ModalityMinimum No. of supervised studies personally performed and interpretedMinimum No. of additional supervised studies interpreted but not personally performedObtain written/signed endorsement from 3 attending physicians attesting to the following:

      1. Explain why letter author is qualified to write the letter.
      Examples: (1) possession of a relevant national certificate or certification in u/s, (2) history of teaching at relevant u/s workshops, (3) history of performing and interpreting diagnostic u/s examinations at their home institution, with an estimated annual volume of relevant u/s examinations that they personally perform and interpret and number of years they have practiced this modality of diagnostic u/s.


      2. Describe the letter author's relationship to the candidate applying for POCUS privileging.

      3. Include a specific attestation statement listed below as pertains to the POCUS domain(s) being discussed (see below).

      Each supporting letter should be from an attending physician who has directly observed candidates’ competence for the given POCUS application.
      Expertise Pathway: Attestation Statements for POCUS Modalities
      Focused airway u/s3020“I personally attest that Dr. <Insert Name> is qualified to perform focused airway u/s. Specifically, in my time working with him/her, I observed that he/she could properly use u/s to evaluate for, among other things, the following: laryngo-tracheal anatomy and endobronchial vs esophageal vs endotracheal intubation.”
      FAST exam3020“I personally attest that Dr. <Insert Name> is qualified to perform a FAST exam. Specifically, in my time working with him/her, I have observed that he/she could properly use u/s to evaluate for life-threatening conditions in trauma patients, including but not limited to: intraperitoneal fluid/hemorrhage and pericardial effusion/hemopericardium.”
      Focused cardiac u/s50100“I personally attest that Dr. <Insert Name> is qualified to perform focused cardiac u/s. Specifically, in my time working with him/her, I have observed that he/she could properly use cardiac u/s to evaluate for, among other things, the following: pericardial effusion/cardiac tamponade, gross left ventricular dysfunction, gross right ventricular dysfunction, and gross hypovolemia.”
      Focused gastric u/s3020“I personally attest that Dr. <Insert Name> is qualified to perform focused gastric u/s. Specifically, in my time working with him/her, I observed that he/she could properly use u/s to evaluate for, among other things, the following: full stomach (defined as solid gastric content or clear fluid in excess of baseline secretions [Grade 2 antrum]).”
      Focused pleural and lung u/s3020“I personally attest that Dr. <Insert Name> is qualified to perform focused lung u/s. Specifically, in my time working with him/her, I have observed that he/she could properly use lung u/s to evaluate for, among other things, the following: pneumothorax, pleural effusions, interstitial syndromes, and consolidation.”
      Focused u/s for DVT3020“I personally attest that Dr. <Insert Name> is qualified to perform focused u/s for evaluation of DVT. Specifically, in my time working with him/her, I have observed that he/she could properly use u/s to evaluate for, among other things, the following: a DVT in the proximal lower extremity veins and in the internal jugular vein.
      NOTE. Based on the 2019 Committee Work Product on Diagnostic Point-of-Care Ultrasound of the American Society of Anesthesiologists. (A copy of the full text can be obtained from ASA, 1061 American Ln, Schaumburg, IL 60173-4973 or online at www.asahq.org.).

      Based on the 2019 Committee Work Product on Diagnostic Point-of-Care Ultrasound of the American Society of Anesthesiologists. A copy of the full text can be obtained from ASA, 1061 American Lane Schaumburg, IL 60173-4973 or online at www.asahq.org 2021

      Abbreviations: DVT, deep vein thrombosis; FAST, focused assessment with sonography in trauma; POCUS, point-of-care ultrasound; u/s, ultrasound.
      Examples: (1) possession of a relevant national certificate or certification in u/s, (2) history of teaching at relevant u/s workshops, (3) history of performing and interpreting diagnostic u/s examinations at their home institution, with an estimated annual volume of relevant u/s examinations that they personally perform and interpret and number of years they have practiced this modality of diagnostic u/s.
      Table 13POCUS Curriculum Levels of Competency
      Competency LevelLevel DescriptionIncluded Competencies
      Level 1 – Core
      • Expected standard of knowledge and practice
      • Generic and basic competences to be obtained during residency training
      • Able to perform common u/s examinations and interventions safely and accurately
      • Able to recognize normal and abnormal anatomy and pathology
      • Able to use u/s in real time to guide common invasive procedures
      • Able to recognize when consultation for a second opinion is indicated
      • Able to understand benefits of u/s imaging and its value and relationship to other imaging modalities used in perioperative medicine
      Level 2 – Extended
      • More advanced level of skill and practice; level 2 practice for clinicians with specialized interest in u/s
      • Overlapping nature of practice is proposed such that a clinician may be level 2 in one area (ie, vascular access) and level 1 in another (ie, regional anesthesia).
      • Significant experience of level 1 practice (ie, >12 months)
      • Able to perform the complete range of examinations
      • Able to recognize significant organ system-specific pathology
      • Able to use u/s to guide full range of procedures related to practice area
      • Able to act as mentor and instructor for level 1 clinicians
      • Able to accept referrals from level 1 clinicians
      Level 3 –Advanced
      • Specialized and advanced training (ie, advanced echocardiography training)
      • Level 3 practice is unlikely to be pertinent to most practicing perioperative clinicians.
      • Able to accept referrals from level 2 clinicians and perform specialized examinations
      • Level 3 clinicians are involved in all areas of u/s training and participate in u/s research.
      NOTE. Adapted from the Association of Anaesthetists of Great Britain and Ireland, the Royal College of Anaesthetists, and the Intensive Care Society's “Ultrasound in Anaesthesia and Intensive Care: A Guide to Training”.

      Association of Anaesthestists of Great Britain and Ireland, The Royal College of Anaesthetists, The Intensive Care Society. Ultrasound in anaesthesia and intensive care: A guide to training. Available at: https://anaesthetists.org/Home/Resources-publications/Guidelines/Ultrasound-in-anaesthesia-and-intensive-care-a-guide-to-training. Accessed January 27, 2021.

      Abbreviations: CCM, critical care medicine; u/s, ultrasound.
      Given the expertise and familiarity of cardiothoracic anesthesiologists with echocardiography and perioperative ultrasound applications, it is natural to conclude that they should play an important role in all aspects of POCUS education.

      Conclusions

      POCUS is a valuable bedside diagnostic tool for the expeditious diagnosis of a variety of acute and life-threatening conditions, clearly earning its burgeoning reputation as the 21st-century stethoscope. For each organ system evaluated, the application of POCUS has its own unique advantages. LUS has better sensitivity and specificity over CXR for certain lung conditions, such as PTX, pulmonary edema, lung consolidation, and pleural effusion.
      • Ye X
      • Xiao H
      • Chen B
      • et al.
      Accuracy of lung ultrasonography versus chest radiography for the diagnosis of adult community-acquired pneumonia: Review of the literature and meta-analysis.
      ,
      • Ding W
      • Shen Y
      • Yang J
      • et al.
      Diagnosis of pneumothorax by radiography and ultrasonography: A meta-analysis.
      ,
      • Maw AM
      • Hassanin A
      • Ho MP
      • et al.
      Diagnostic accuracy of point-of-care lung ultrasonography and chest radiography in adults with symptoms suggestive of acute decompensated heart failure: A systematic review and meta-analysis.
      Cardiac ultrasound has a central role in the evaluation of challenging hemodynamic situations and undifferentiated shock states. Combinations of POCUS modalities, such as LUS along with FOCUS, have higher rates of accurate diagnosis in complex situations and multiorgan system involvement.
      • Coiro S
      • Rossignol P
      • Ambrosio G
      • et al.
      Prognostic value of residual pulmonary congestion at discharge assessed by lung ultrasound imaging in heart failure.
      ,
      • Ohman J
      • Harjola VP
      • Karjalainen P
      • et al.
      Focused echocardiography and lung ultrasound protocol for guiding treatment in acute heart failure.
      Diagnosis and treatment using POCUS should be within the clinical context of the patient, and the ultrasonographer must be aware fully of the limitations.
      • Blanco P
      • Volpicelli G.
      Common pitfalls in point-of-care ultrasound: A practical guide for emergency and critical care physicians.
      ,
      • Johnson GGRJ
      • Kirkpatrick AW
      • Gillman LM.
      Ultrasound in the surgical ICU: Uses, abuses, and pitfalls.
      Analogous to the National Board of Echocardiography training and certification standards for echocardiography, standardizing POCUS education and delineating competency levels also are central to ensuring appropriate quality assurance. This is even more critical as POCUS use increases and more physicians seek to attain POCUS expertise to incorporate this technology more widely into routine clinical practice. With the current available and growing evidence of clinical value of POCUS, its utility across the perioperative arena adds enormous benefit to clinical decision-making.

      Conflict of Interest

      The authors declare no competing interests.

      Appendix. Supplementary materials

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