Proactive Approach to Peri-Induction Hemodynamic Management in Critically Ill Patients

      Keywords

      Tracheal intubation of critically ill patients, outside of the operating room, is a high-risk, common procedure, frequently associated with adverse events, which can be exacerbated by poor planning and lack of sufficient equipment and appropriately skilled physicians.
      • Russotto V
      • Myatra SN
      • Laffey JG
      • et al.
      Intubation Practices and Adverse Peri-intubation Events in Critically Ill Patients From 29 Countries.
      ,
      • Natt B
      • Mosier J.
      Airway Management in the Critically Ill Patient.
      Shedding additional insights into this important area, Russotto et al. recently published their results on Intubation Practices and Adverse Peri-intubation Events in Critically Ill Patients From 29 Countries” in JAMA.
      • Russotto V
      • Myatra SN
      • Laffey JG
      • et al.
      Intubation Practices and Adverse Peri-intubation Events in Critically Ill Patients From 29 Countries.
      The authors congratulate the authors on their comprehensive analysis of a frequently occurring and dangerous event in the care of critically ill patients. As evidenced by the work of Russotto et al, appreciation of deranged physiology, in addition to anticipation of difficult anatomic airways, are imperative to navigate these encounters while minimizing harm.
      • Mosier JM
      • Joshi R
      • Hypes C
      • Pacheco G
      • Valenzuela T
      • Sakles JC.
      The Physiologically Difficult Airway.
      In their observational study, the authors analyzed 2964 consecutive adult patients who underwent endotracheal intubation in intensive care units, emergency rooms, and wards distributed across 197 sites dispersed throughout 29 countries. The overall ICU mortality in this diverse cohort was 32.8%. Interestingly, while the primary reason necessitating intubation was respiratory in nature (52.3%), a great majority of adverse peri-intubation events were cardiovascular instability (42.6%). In fact, intubation was complicated by severe hypoxemia in only 9.3% of patients. First-pass success was found at rates similar to previously published literature and video laryngoscopy was used in a minority of patients (17.1%).
      • Lascarrou JB
      • Boisrame-Helms J
      • Bailly A
      • et al.
      Video Laryngoscopy vs Direct Laryngoscopy on Successful First-Pass Orotracheal Intubation Among ICU Patients: A Randomized Clinical Trial.
      Not surprisingly, the authors found a positive correlation with rates of major adverse events associated with an increasing number of attempts to secure the airway (43.2% [one attempt] vs 51.5% [two attempts] vs 58.0 % [three attempts]). It is worth noting that waveform capnography was not utilized in a majority of patients in whom accidental esophageal intubation occurred. The authors rightfully pointed out the importance of first-pass success, equipment to confirm endobronchial position of the endotracheal tube (e.g., capnography or bronchoscopy), and overall expertise of the operator in airway management. Clearly, clinicians should aim to achieve highest chance of first-pass intubation in these most vulnerable patients, though, admittedly, expertise and equipment are not always modifiable variables.
      Recognizing that cardiovascular instability predominated over other major adverse events, it becomes apparent that an assessment of and, if feasible, subsequent optimization of the patient's hemodynamic state peri-intubation should be undertaken prior to induction with sedative-hypnotics. Understandably, many intubations in the ICU occur under time-limited conditions that preclude an extensive evaluation . However, it is the authors' experience that a few extra minutes of evaluation and preparation may avert cardiovascular instability, thereby mitigating downstream morbidity and mortality.
      Perturbations in hemodynamic status are common and represent a major factor portending mortality in acute lung disease, including acute respiratory distress syndrome.
      • Vieillard-Baron A
      • Matthay M
      • Teboul JL
      • et al.
      Experts' opinion on management of hemodynamics in ARDS patients: focus on the effects of mechanical ventilation.
      Interventions studied previously to address hemodynamic instability accompanying intubation included administration of a 500-mL crystalloid bolus prior to intubation and early start of norepinephrine postintubation in the case of hypotension.
      • Jaber S
      • Jung B
      • Corne P
      • et al.
      An intervention to decrease complications related to endotracheal intubation in the intensive care unit: a prospective, multiple-center study.
      ,
      • Janz DR
      • Casey JD
      • Semler MW
      • et al.
      Effect of a fluid bolus on cardiovascular collapse among critically ill adults undergoing tracheal intubation (PrePARE): a randomised controlled trial.
      The intent of fluid therapy in this context is to augment left ventricular end-diastolic volume in an effort to improve cardiac output, thereby compensating for any detrimental effects associated with induction including pharmacologic effects and secondary declines in sympathetic outflow. However, vigilance must be maintained regarding the sudden and detrimental impact of positive- pressure ventilation with regard to the function of the right ventricle in both systole and diastole, with the attendant narrow band of optimal preload. The achievement of optimal right ventricular preload is challenged by the disadvantageous effect of dynamic changes in pleural/transpulmonary pressures on pulmonary vascular mechanics. Further, the development of acute core pulmonale, which complicates up to 25% cases of ARDS, may be precipitated by the indiscriminate administration of fluid.
      • Cortes-Puentes GA
      • Oeckler RA
      • Marini JJ.
      Physiology-guided management of hemodynamics in acute respiratory distress syndrome.
      These deleterious effects are exacerbated by the concurrent addition of positive airway pressure, leading to drastic changes in left ventricular preload and right ventricular afterload.
      • Mahmood SS
      • Pinsky MR.
      Heart-lung interactions during mechanical ventilation: the basics.
      ,
      • Alviar CL
      • Miller PE
      • McAreavey D
      • et al.
      Positive Pressure Ventilation in the Cardiac Intensive Care Unit.
      This sudden increase of right ventricular afterload following intubation, combined with concomitant hypoxemia, hypercarbia, and acidosis as result of respiratory failure, make for a volatile hemodynamic situation. In addition to this already complex and potentially fragile clinical state, additional etiologies of hypoxemia or respiratory distress, such as pulmonary embolism, may exacerbate the risks associated with fluid bolus administration. In fact, a large fluid bolus in the setting of hypotension may be contraindicated, as this additional right ventricular preload may precipitate cardiovascular collapse. In contrast, it may not be too far-fetched to state that an ARDS pneumonia patient who failed traditional medical management including aggressive diuresis, often over several days, may be intravascularly volume-depleted. In these patients, a 500-mL fluid bolus may not restore intravascular volume sufficiently to provide hemodynamic stability peri-intubation. For these reasons, the insidious right ventricular dysfunction that commonly ensues in hypoxemic and hypercarbic patients may make aggressive fluid loading without concomitant inotropic support a precarious exercise.
      Sepsis itself, as a common cause for ARDS, may further complicate the hemodynamic situation through the genesis of septic cardiomyopathy (SCM).
      • Nabzdyk CS
      • Couture EJ
      • Shelton K
      • Cudemus G
      • Bittner EA.
      Sepsis induced cardiomyopathy: Pathophysiology and use of mechanical circulatory support for refractory shock.
      SCM is present in more than 13% of sepsis and septic shock patients, though echocardiographic evidence of myocardial dysfunction is present in up to 60% of patients.
      • Sato R
      • Kuriyama A
      • Takada T
      • Nasu M
      • Luthe SK.
      Prevalence and risk factors of sepsis-induced cardiomyopathy: A retrospective cohort study.
      ,
      • Vieillard-Baron A
      • Caille V
      • Charron C
      • Belliard G
      • Page B
      • Jardin F.
      Actual incidence of global left ventricular hypokinesia in adult septic shock.
      SCM is the result of cytokines’ and other mediators’ (myocardial depressant factors) deleterious effects on the myocardium that reduce the myofibril response to calcium, cause mitochondrial dysfunction, and a downregulation of beta-receptors.
      • Garner LB
      • Willis MS
      • Carlson DL
      • et al.
      Macrophage migration inhibitory factor is a cardiac-derived myocardial depressant factor.
      • Pathan N
      • Sandiford C
      • Harding SE
      • Levin M.
      Characterization of a myocardial depressant factor in meningococcal septicemia.
      • Binck BW
      • Tsen MF
      • Islas M
      • et al.
      Bone marrow-derived cells contribute to contractile dysfunction in endotoxic shock.
      SCM can occur in a subtle and self-limited (seven-14d) way or may present itself as cardiogenic shock that necessitates inotropic or even mechanical circulatory support.
      • Nabzdyk CS
      • Couture EJ
      • Shelton K
      • Cudemus G
      • Bittner EA.
      Sepsis induced cardiomyopathy: Pathophysiology and use of mechanical circulatory support for refractory shock.
      Taken together, it is apparent that certain patients necessitating intubation in the ICU primarily for respiratory indications may have benefitted from the antecedent administration of inotropic support prior to proceeding with intubation. Reactive initiation (or uptitration) of vasopressor support, as suggested by the authors after intubation, implies the development of hemodynamic instability that serves as a trigger to institute an intervention. This stands in stark contrast to a proactive approach to management. Initiation of a vasoactive infusion during ongoing hypotension may take minutes to show effect and require dose titration to achieve an optimal impact. Consequently, this intervention by definition is not suited to prevent sudden, and potentially catastrophic, cardiovascular collapse. Given the marginal physiologic reserve aggravated by the rapidity of deterioration commonly seen in acute right ventricular failure at the time of intubation in compromised patients, proactive and preventative management steps are essential to preempt catastrophic cardiovascular collapse (Figure 1). For these reasons, above-mentioned interventions as discussed by the authors do not provide sufficient clinical safety margins and place patients at undue risk for iatrogenic insult.
      Figure 1
      Figure 1Proactive Approach to Peri-Induction Hemodynamic Management in Critically Ill Patients
      The authors further discussed the impact of choice of sedative-hypnotic agent on peri-intubation hemodynamics. In this study, propofol predominantly was used as the induction agent. The authors concur with the authors that, ‘pound-for-pound,’ propofol is more likely to cause hypotension compared to ketamine and etomidate. Hence, it is not surprising that ketamine is recommended by the Intensive Care Society (ICS) for the tracheal intubation of critically ill patients; whereas the ICS does not recommend the routine use of etomidate due to the concerns for adrenal suppression.
      • Higgs A
      • McGrath BA
      • Goddard C
      • et al.
      Guidelines for the management of tracheal intubation in critically ill adults.
      Further, selection of the ideal pharmacologic approach for induction requires not only identification of the appropriate agent (or combination of agents) but also the integration of variables and pathophysiologic data unique to the patient to facilitate the development of an individualized strategy that intentionally is dose-optimized. Truly, a “one dose fits all” approach is suboptimal and necessitates a comprehensive understanding of pharmacokinetics and pharmacodynamics for minimizing iatrogenic risk.
      Still, it is vital to recognize that the choice of induction agent alone, even if appropriately dose-adjusted, will not suffice to preempt peri-intubation cardiovascular instability reliably in a majority of patients. Regardless of the sedative-hypnotic agent selected, induction yields an acute decline in adrenergic tone originating from the withdrawal of endogenous sympathetic output.
      • Ebert TJ
      • Muzi M
      • Berens R
      • Goff D
      • Kampine JP.
      Sympathetic responses to induction of anesthesia in humans with propofol or etomidate.
      A false sense of security can exist with administration of either ketamine or etomidate, both of which have been demonstrated to cause postadministration hypotension.
      • Groth CM
      • Acquisto NM
      • Khadem T.
      Current practices and safety of medication use during rapid sequence intubation.
      ,
      • Abou Arab O
      • Fischer MO
      • Carpentier A
      • et al.
      Etomidate-induced hypotension: a pathophysiological approach using arterial elastance.
      Thus, it is important to approach each patient thoughtfully, with a high-index of suspicion for peri-intubation hemodynamics stability, regardless of induction agent chosen.
      Bearing these inherent physiologic nuances and specifically targeting the modifiable aspects of cardiovascular management, the authors propose a simple proactive hemodynamic management approach to urgent intubation in critically ill patients amid preoxygenation and preparation of airway equipment. In the preintubation presence of, or high index of suspicion for the subsequent development of postintubation tachycardia or overt hypotension, the authors suggest a simple sequence of steps (see Figure 1 for more details):
      • 1.
        Assess the current fluid status and myocardial contractility.
      • 2.
        Initiate (or increase preexisting) vasopressor infusions in preparation for intubation.
      • 3.
        Augment mean arterial pressure (MAP) to at least 75 mmHg or >20 mmHg from baseline.
      • 4.
        Prepare or consider preemptive bolus administration of vasopressor/inotropic agents.
      • 5.
        Load fluid if sufficient time, high suspicion of hypovolemia and low likelihood of (right) ventricular failure.
      • 6.
        Activate Mechanical Circulatory Support (MCS) in selected patients, ideally in an anticipatory fashion.
      Russotto et al.’s recent study served as an important reminder that individuals requiring intubation for the performance of mechanical ventilation are at high risk for serious peri-induction complications; the most common, and perhaps avoidable, is severe cardiovascular instability. Pathophysiologic strain on the right ventricle requires vigilance, rapid performance of appropriate evaluation, followed by the institution of preinduction optimization to minimize acute deterioration and potential hemodynamic collapse. Avoidance of inadvertent excess fluid administration or, conversely, inadequate resuscitation, is essential and best achieved as assisted by physiologic variables and echocardiographic imaging. Pharmacologic considerations include the selection of an appropriate sedative agent with dose adjustment to mitigate iatrogenic risk, supporting of systemic vascular resistance with carefully titrated vasopressor therapy, and augmentation of biventricular contractile function with inotropes if necessary. It is imperative that a robust strategy, thoughtfully developed in concert with sound physiologic guidance, be utilized to safely support critically ill patients requiring intubation.

      Declaration of Conflict of Interest

      The authors have no conflicts of interest to declare.

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