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Original Article| Volume 37, ISSUE 3, P407-414, March 2023

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Stroke Volume and Arterial Pressure Fluid Responsiveness in Patients With Elevated Stroke Volume Variation Undergoing Major Vascular Surgery: A Prospective Intervention Study

  • Arabella Fischer
    Footnotes
    Affiliations
    Division of Cardiac Thoracic Vascular Anesthesia and Intensive Care Medicine, Department of Anesthesia, Intensive Care Medicine and Pain Medicine, Medical University Vienna, Vienna, Austria
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  • Johannes Menger
    Footnotes
    Affiliations
    Division of Cardiac Thoracic Vascular Anesthesia and Intensive Care Medicine, Department of Anesthesia, Intensive Care Medicine and Pain Medicine, Medical University Vienna, Vienna, Austria

    Department of Anesthesiology, Intensive Care, Emergency and Pain Medicine, University Hospital of Würzburg, Würzburg, Germany
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  • Mohamed Mouhieddine
    Affiliations
    Division of Cardiac Thoracic Vascular Anesthesia and Intensive Care Medicine, Department of Anesthesia, Intensive Care Medicine and Pain Medicine, Medical University Vienna, Vienna, Austria
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  • Mathias Seidel
    Affiliations
    Division of Cardiac Thoracic Vascular Anesthesia and Intensive Care Medicine, Department of Anesthesia, Intensive Care Medicine and Pain Medicine, Medical University Vienna, Vienna, Austria
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  • Maximilian Edlinger-Stanger
    Affiliations
    Division of Cardiac Thoracic Vascular Anesthesia and Intensive Care Medicine, Department of Anesthesia, Intensive Care Medicine and Pain Medicine, Medical University Vienna, Vienna, Austria
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  • Michele Bevilacqua
    Affiliations
    Division of Cardiac Thoracic Vascular Anesthesia and Intensive Care Medicine, Department of Anesthesia, Intensive Care Medicine and Pain Medicine, Medical University Vienna, Vienna, Austria
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  • Jonas Brugger
    Affiliations
    Center for Medical Statistics, Informatics and Intelligent Systems, Medical University Vienna, Vienna, Austria
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  • Michael Hiesmayr
    Affiliations
    Center for Medical Statistics, Informatics and Intelligent Systems, Medical University Vienna, Vienna, Austria
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  • Martin Dworschak
    Correspondence
    Address correspondence to Martin Dworschak, MD, MBA, Division of Cardiac Thoracic Vascular Anesthesia and Intensive Care Medicine, Department of Anesthesia, Intensive Care Medicine and Pain Medicine, General Hospital Vienna, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria
    Affiliations
    Division of Cardiac Thoracic Vascular Anesthesia and Intensive Care Medicine, Department of Anesthesia, Intensive Care Medicine and Pain Medicine, Medical University Vienna, Vienna, Austria
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  • Author Footnotes
    1 A.F. and J.M. contributed equally to this work.
Open AccessPublished:November 24, 2022DOI:https://doi.org/10.1053/j.jvca.2022.11.028

      Objectives

      The identification of potential hemodynamic indicators to increase the predictive power of stroke-volume variation (SVV) for mean arterial pressure (MAP) and stroke volume (SV) fluid responsiveness.

      Design

      A prospective intervention study.

      Setting

      At a single-center university hospital.

      Participants

      Nineteen patients during major vascular surgery with 125 fluid interventions.

      Interventions

      When SVV ≥13% occurred for >30 seconds, 250 mL of Ringer's lactate were given within 2 minutes.

      Measurements and Main Results

      Hemodynamic variables, such as pulse-pressure variation (PPV) and dynamic arterial elastance (Edyn), were measured by pulse power-wave analysis. The outcomes were MAP and SV responsiveness, defined as an increase of at least 10% of MAP and SV within 5 minutes of the fluid intervention. Of the fluid interventions, 48% were MAP-responsive, and 66% were SV-responsive. The addition of PPV and Edyn cut-off values to the SVV cut-off decreased sensitivity from 1-to-0.66 to-0.82, and concomitantly increased specificity from 0-to- 0.65-to-0.93 for the prediction of MAP and SV responsiveness in the authors’ study setting. The areas under the receiver operating characteristic curves of PPV and Edyn for the prediction of MAP responsiveness were 0.79 and 0.75, respectively. The areas under the receiver operating characteristic curves for PPV and Edyn to predict SV responsiveness were 0.85 and 0.77, respectively.

      Conclusions

      The PPV and Edyn showed good accuracy for the prediction of MAP and SV responsiveness in patients with elevated SVV during vascular surgery. Either PPV or Edyn may be used in conjunction with SVV to better predict MAP and SV fluid responsiveness in patients undergoing vascular surgery.

      Key Words

      ADEQUATE ORGAN PERFUSION PRESSURE and, consequently, organ blood flow, are crucial to prevent tissue hypoperfusion, organ injury, and mitigate inflammatory response.
      • Pinsky MR.
      Functional hemodynamic monitoring.
      Therefore, the maintenance of adequate mean arterial pressure (MAP) and stroke volume (SV) are 2 important goals during major surgery. Stable MAP and SV values were associated with fewer postoperative complications, such as postoperative infections, acute kidney injury, myocardial injury, and a reduced hospital length of stay, as well as lower hospital mortality.
      • Pearse RM
      • Harrison DA
      • MacDonald N
      • et al.
      Effect of a perioperative, cardiac output-guided hemodynamic therapy algorithm on outcomes following major gastrointestinal surgery: A randomized clinical trial and systematic review.
      • Wesselink EM
      • Kappen TH
      • Torn HM
      • et al.
      Intraoperative hypotension and the risk of postoperative adverse outcomes: A systematic review.
      • Hamilton MA
      • Cecconi M
      • Rhodes A.
      A systematic review and meta-analysis on the use of preemptive hemodynamic intervention to improve postoperative outcomes in moderate and high-risk surgical patients.
      • Funk DJ
      • HayGlass KT
      • Koulack J
      • et al.
      A randomized controlled trial on the effects of goal-directed therapy on the inflammatory response open abdominal aortic aneurysm repair.
      Fluid resuscitation is the first measure to maintain MAP and SV. However, excessive fluid overload is associated with peripheral and pulmonary edema.
      • Cecconi M
      • De Backer D
      • Antonelli M
      • et al.
      Consensus on circulatory shock and hemodynamic monitoring. Task force of the European Society of Intensive Care Medicine.
      The prediction of MAP and SV fluid responsiveness is, therefore, crucial in order to give fluids only when they are needed.
      One of two ways to determine MAP and SV fluid responsiveness is the evaluation of dynamic variations over time of SV (SVV), pulse pressure (PPV), or the ratio of PPV-SVV, also known as dynamic arterial elastance (Edyn), during mechanical ventilation.
      • Messina A
      • Pelaia C
      • Bruni A
      • et al.
      Fluid challenge during anesthesia: A systematic review and meta-analysis.
      • Lee C-T
      • Lee T-S
      • Chiu C-T
      • et al.
      Mini-fluid challenge test predicts stroke volume and arterial pressure fluid responsiveness during spine surgery in prone position.
      • Cannesson M
      • Le Manach Y
      • Hofer CK
      • et al.
      Assessing the diagnostic accuracy of pulse pressure variations for the prediction of fluid responsiveness: A “gray zone” approach.
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      • García MIM
      • Cano AG
      • Romero MG.
      Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients.
      • Marik PE
      • Cavallazzi R
      • Vasu T
      • et al.
      Dynamic changes in arterial waveform derived variables and fluid responsiveness in mechanically ventilated patients: A systematic review of the literature.
      Second, minifluid challenges can be performed to assess their effect on MAP and SV, which indicates if further fluid resuscitation is needed.
      • Messina A
      • Pelaia C
      • Bruni A
      • et al.
      Fluid challenge during anesthesia: A systematic review and meta-analysis.
      ,
      • Lee C-T
      • Lee T-S
      • Chiu C-T
      • et al.
      Mini-fluid challenge test predicts stroke volume and arterial pressure fluid responsiveness during spine surgery in prone position.
      Minifluid challenges of 100 mL more reliably predicted MAP and SV responsiveness than dynamic predictors such as SVV, PPV, or Edyn.
      • Lee C-T
      • Lee T-S
      • Chiu C-T
      • et al.
      Mini-fluid challenge test predicts stroke volume and arterial pressure fluid responsiveness during spine surgery in prone position.
      ,
      • Muller L
      • Toumi M
      • Bousquet PJ
      • et al.
      An increase in aortic blood flow after an infusion of 100 ml colloid over 1 minute can predict fluid responsiveness: The mini-fluid challenge study.
      ,
      • Biais M
      • De Courson H
      • Lanchon R
      • et al.
      Mini-fluid challenge of 100 ml of crystalloid predicts fluid responsiveness in the operating room.
      However, dynamic predictors may be more attractive, as no administration of fluid is required. Dynamic predictors mostly were assessed alone,
      • Messina A
      • Pelaia C
      • Bruni A
      • et al.
      Fluid challenge during anesthesia: A systematic review and meta-analysis.
      • Lee C-T
      • Lee T-S
      • Chiu C-T
      • et al.
      Mini-fluid challenge test predicts stroke volume and arterial pressure fluid responsiveness during spine surgery in prone position.
      • Cannesson M
      • Le Manach Y
      • Hofer CK
      • et al.
      Assessing the diagnostic accuracy of pulse pressure variations for the prediction of fluid responsiveness: A “gray zone” approach.
      ,
      • Biais M
      • De Courson H
      • Lanchon R
      • et al.
      Mini-fluid challenge of 100 ml of crystalloid predicts fluid responsiveness in the operating room.
      • Lanchon R
      • Nouette-Gaulain K
      • Stecken L
      • et al.
      Dynamic arterial elastance obtained using arterial signal does not predict an increase in arterial pressure after a volume expansion in the operating room.
      • Willars C
      • Dada A
      • Hughes T
      • et al.
      Functional haemodynamic monitoring: The value of SVV as measured by the LiDCORapid in predicting fluid responsiveness in high risk vascular surgical patients.
      and less often in combination with other variables.
      • Messina A
      • Pelaia C
      • Bruni A
      • et al.
      Fluid challenge during anesthesia: A systematic review and meta-analysis.
      ,
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      ,
      • García MIM
      • Cano AG
      • Romero MG.
      Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients.
      For example, SVV ≥10% alone predicted SV responsiveness in 80%,
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      and MAP responsiveness in about one-third-to-two-thirds
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      ,
      • García MIM
      • Cano AG
      • Romero MG.
      Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients.
      of all fluid interventions. Edyn >0.8911 or >0.6510 could predict MAP responsiveness (area under the receiver operating characteristic curve [AUROC] 0.99) well in mechanically ventilated patients in the intensive care unit (ICU),
      • García MIM
      • Cano AG
      • Romero MG.
      Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients.
      but only moderately (AUROC 0.71) in patients during neurosurgical or abdominal surgery,
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      who received fluid if SVV ≥10%.
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      ,
      • García MIM
      • Cano AG
      • Romero MG.
      Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients.
      Therefore, it remains unclear if SVV combined with other hemodynamic variables would improve prediction of MAP and SV responsiveness, especially in patients with vascular disease. Patients with vascular disease undergoing surgery are particularly challenging because vascular disease may alter arterial load and the accuracy of hemodynamic variables to predict MAP or SV responsiveness. To the authors’ knowledge, a comparison of SVV alone versus combined with other hemodynamic variables to predict MAP and SV responsiveness has not yet been performed in patients undergoing vascular surgery.
      • Funk DJ
      • HayGlass KT
      • Koulack J
      • et al.
      A randomized controlled trial on the effects of goal-directed therapy on the inflammatory response open abdominal aortic aneurysm repair.
      ,
      • Cannesson M
      • Le Manach Y
      • Hofer CK
      • et al.
      Assessing the diagnostic accuracy of pulse pressure variations for the prediction of fluid responsiveness: A “gray zone” approach.
      ,
      • Lanchon R
      • Nouette-Gaulain K
      • Stecken L
      • et al.
      Dynamic arterial elastance obtained using arterial signal does not predict an increase in arterial pressure after a volume expansion in the operating room.
      ,
      • Willars C
      • Dada A
      • Hughes T
      • et al.
      Functional haemodynamic monitoring: The value of SVV as measured by the LiDCORapid in predicting fluid responsiveness in high risk vascular surgical patients.
      Therefore, the aim of this study was to identify additional hemodynamic predictors of fluid responsiveness to increase the predictive power of SVV during major vascular surgery.

      Methods

      Study Design and Population

      This prospective intervention study was conducted at the General Hospital of Vienna, Medical University of Vienna after approval by the authors’ local ethic committee and written informed consent by all patients. Patients undergoing major vascular surgery, such as peripheral arterial surgery (except for carotid artery surgery) and open abdominal aortic surgery, were included. The exclusion criteria were patients <18 years of age and the absence of cardiac sinus rhythm at anesthesia induction.

      Intervention

      A 20-G arterial catheter was placed in the radial artery prior to anesthesia induction, zeroed to atmospheric pressure, and a flush test was applied to ascertain optimal damping. The minimally invasive LiDCOrapid device (LiDCO, Lake Villa, IL) was connected to the monitoring screen (Infinity Delta, Drägerwerk AG, Lübeck, Germany) according to the manufacturer's recommendations. For each patient, weight, height, age, sex, and patient type were imputed into the LiDCOrapid device to internally scale the results. Fluid, noradrenaline, or dobutamine interventions were given according to an active decision support system from skin incision to wound closure (Fig 1).
      • Menger J
      • Fischer A
      • Mouhieddine M
      • et al.
      Evaluation of an active decision support system for hemodynamic optimization during elective major vascular surgery.
      Every intervention was noted by a study anesthesiologist.
      • Menger J
      • Fischer A
      • Mouhieddine M
      • et al.
      Evaluation of an active decision support system for hemodynamic optimization during elective major vascular surgery.
      Fluid interventions with 250 mL of Ringer's lactate solution were given under pressure within 2 minutes once SVV exceeded 13% for >30 seconds (Fig 1). No baseline fluid was applied. Volume-controlled ventilation, with a tidal volume of 8 mL/kg ideal body weight was applied. Anesthetic technique and monitoring have been previously described in detail; and feasibility, as well as adherence to the active decision support system, in this prospective intervention study have been published.
      • Menger J
      • Fischer A
      • Mouhieddine M
      • et al.
      Evaluation of an active decision support system for hemodynamic optimization during elective major vascular surgery.
      Fig 1
      Fig. 1Protocol of the active decision support system for fluid, noradrenaline, and dobutamine interventions. For this exploratory analysis only fluid interventions performed because of SVV ≥13% (red part of algorithm) were included. Reprinted and adapted from Minerva Anestesiologica 85:288-97, Menger J, Fischer A, Mouhieddine M, Seidel M, Edlinger-Stanger M, Bevilacqua M, et al. Evaluation of an active decision support system for hemodynamic optimization during elective major vascular surgery, Copyright (2019), with permission from Minerva Medica. BIS, bispectral index; CO, cardiac output; COBL, CO at baseline (before induction of anesthesia); MAP, mean arterial pressure; MAPBL, MAP at baseline (before induction of anesthesia); RL, Ringer's lactate; SV, stroke volume; SVV, stroke volume variation.

      Data Collection and Processing

      For this exploratory analysis, the study authors screened all fluid interventions because of SVV ≥13% according to the active decision support system as documented by the study anesthesiologist (Fig 1, red part). The authors exported the beat-by-beat continuous hemodynamic data from the stored database of the LiDCOrapid device. Performed fluid interventions only were included if the database verified a median SVV ≥13% at the start of the fluid intervention (t0). Fluid interventions, followed by any other interventions within 5 minutes, were excluded. Moreover, fluid interventions not performed with Ringer's lactate were excluded (Fig 2).
      Fig 2
      Fig. 2Flowchart of included fluid interventions.
      • Menger J
      • Fischer A
      • Mouhieddine M
      • et al.
      Evaluation of an active decision support system for hemodynamic optimization during elective major vascular surgery.
      All hemodynamic variables listed in Table 1 were assessed as potential additional predictors for MAP and SV responsiveness in fluid interventions performed if SVV ≥13%. The LiDCOrapid device automatically averages dynamic variables over 10 seconds and updates calculations every 4 heart beats (Table 1). Such dynamic variables were SVV, PPV, systolic pressure variation and heart rate variation. The LiDCOrapid device determines SVV as (SVmax – SVmin) × 100 / ([SVmax + SVmin] / 2). In addition, the LiDCOrapid device stores MAP, systolic, and diastolic arterial pressures, heart rate, SV, cardiac index, heart rate variation, as well as systemic vascular resistance index. Finally, the authors calculated arterial compliance, Edyn, arterial elastance, and arterial resistance (Table 1). The median value of each hemodynamic variable in Table 1 for every minute from the beat-by-beat continuous hemodynamic data was calculated and paired with the fluid intervention data. The start of every fluid intervention was coded as time 0 (t0). The authors determined median values at t0 and at minutes 1-to-5 (t1-5) for the hemodynamic data shown in Table 1. For every listed hemodynamic variable, the change in relation to t0 was calculated at t1-to-5. If the fluid intervention (at t0, for example, at 8:00) was followed by the next intervention exactly after 5 minutes (at t5, for example, at 8:05), the hemodynamic values at t5 were considered both as effect at minute 5 of the previous fluid intervention and as baseline at minute 0 (t0) for the next fluid intervention. This was done because the authors did not expect to see an immediate effect of the starting fluid intervention at t0.
      Table 1Additional Hemodynamic Variables Assessed as Potential Predictors for MAP and SV Responsiveness in Fluid Interventions Performed if SVV ≥13%
      Hemodynamic VariableDefinitionUnitSource
      MAPmmHgLiDCOrapid device
      SysmmHgLiDCOrapid device
      DiammHgLiDCOrapid device
      HRL/minLiDCOrapid device
      SVmLLiDCOrapid device
      CI= (stroke volume × HR) / body surface areaL/min/m2LiDCOrapid device
      HRV= SD [HR] × 100 / mean [HR]%averaged over 10 seconds and updated every 4 beats by LiDCOrapid device
      SVRI= 80 × (MAP – right arterial pressure) / CI)dynes * s /cm5/m2LiDCOrapid device
      SPV= maximum systolic pressure-minimum systolic pressuremmHgaveraged over 10 seconds and updated every 4 beats by LiDCOrapid device
      PPV= (PPmax – PPmin) × 100 / ([PPmax + PPmin) / 2]) where PP = systolic pressure – diastolic pressure%averaged over 10 seconds and updated every 4 beats by LiDCOrapid device
      Cart= SV / (systolic pressure – diastolic pressure)
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      mL/mmHgcalculated
      Edyn= PPV / SVV
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      ,
      • García MIM
      • Cano AG
      • Romero MG.
      Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients.
      nonecalculated
      Eart= MAP / SV
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      mmHg/mLcalculated
      Rart= MAP / (SV × HR)
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      mmHg *min/Lcalculated
      NOTE. SVV = (SVmax – SVmin) × 100 / ([SVmax + SVmin] / 2).
      Abbreviations: Cart, arterial compliance; CI, cardiac index; Dia, diastolic arterial pressure; Edyn, dynamic arterial elastance; HR, heart rate; HRV, heart rate variation; MAP, mean arterial pressure; PPV, pulse-pressure variation; Rart, arterial resistance; SPV, systolic pressure variation; SV, stroke volume; SVRI, systemic vascular resistance index; Sys, systolic arterial pressure.

      Statistical Analysis

      The study outcomes were MAP and SV responsiveness, defined as an increase of at least 10% of MAP or SV, respectively, within 5 minutes of the fluid intervention. Hemodynamic data were clustered for each patient. Differences in hemodynamic data between MAP or SV responders and nonresponders were assessed using clustered Wilcoxon rank sum test. Differences in numbers between MAP or SV responsive versus nonresponsive fluid interventions were assessed with chi-square tests. Hemodynamic measures at t0 were correlated to MAP and SV fluid responsiveness in multivariate logistic regression models, with MAP or SV responsiveness being the outcome variable. For every model, 1 hemodynamic value at t0 (Table 1) was chosen as a predictor for MAP or SV responsiveness in fluid interventions performed if SVV ≥13%. Odds-ratio and p values were computed for every hemodynamic value at t0. In addition, MAP or SV at t0, administration of noradrenaline and dobutamine, and a random effect for the patient were accounted for in every model. Both PPV and Edyn were the hemodynamic variables, showing the lowest p values in the multivariate logistic regression models, and were, therefore, chosen for further AUROC analysis; univariate logistic regression models were fitted, and the optimal cutoff values for PPV and Edyn, yielding the highest Youden-Index, were calculated to predict MAP or SV responsiveness. Sensitivity and specificity of the optimal cutoff were calculated. The first goal was to compare sensitivity and specificity when using SVV alone or when combining it with PPV and Edyn to predict MAP or SV responsiveness. The authors analyzed to what extent specificity would improve and sensitivity would decrease when adding PPV and Edyn. The second goal was to assess whether PPV and Edyn attained good accuracy with an AUROC ≥0.75
      • Ray P
      • Le Manach Y
      • Riou B
      • et al.
      Statistical evaluation of a biomarker.
      for the prediction of MAP and SV responsiveness. Therefore, ROC curves were drawn, and the AUROC was calculated. Calculations were performed using R, version 3.6.1 or higher (R Foundation for Statistical Computing). Normally distributed data were reported as mean (± SD), and nonnormally distributed data as median (IQR). The categorical data were presented as counts and percentages. No correction for multiple testing was applied; therefore, all p values were of descriptive character.

      Results

      Number of Fluid Interventions

      The entire active decision support system (Fig 1) was evaluated in detail and published previously.
      • Menger J
      • Fischer A
      • Mouhieddine M
      • et al.
      Evaluation of an active decision support system for hemodynamic optimization during elective major vascular surgery.
      In short, 734 fluid, noradrenaline, and dobutamine interventions were carried out according to an operating active decision support system in 32 patients during major vascular surgery. Among the 734 interventions, 200 fluid interventions because of SVV ≥13% were performed, as documented by the study anesthesiologist (Fig 1, red part). Among the 200 fluid interventions, 125 fluid interventions of 19 patients were included in this analysis (Fig 2). The median (IQR) [range] number of fluid interventions per patient was 6 (2-10) (1-16). The baseline characteristics of patients are shown in Table 2.
      Table 2Baseline Characteristics
      Patients (n = 19)
      Sex, n (%)
       Male15 (79)
       Female4 (21)
      Age, y64 ± 11
      BMI, kg/m226 ± 5
      ASA
       II7
       III12
      Procedure, n (%)
       Femoral endarterectomy with patch angioplasty2 (11)
       Aortobifemoral bypass surgery11 (58)
       Femoro-politeal bypass surgery4 (21)
       Femoro-tibial bypass surgery1 (5)
       Femoro-femoral bypass surgery1 (5)
      Anesthesia, n (%)
       General anesthesia with sevoflurane18 (95)
       Total intravenous anesthesia1 (5)
      Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index.

      MAP and SV Responsiveness in Fluid Interventions

      Sixty (48%) fluid interventions were MAP-responsive, and 65 (52%) interventions were MAP non-responsive (Table 3). The maximum change in MAP within 5 minutes was 16% (12-21%) and 5% (2-8%) in MAP-responsive and MAP-nonresponsive interventions, respectively (p < 0.001) (Table 3). The MAP-responsive and MAP-nonresponsive interventions had similar MAP values at t0 (Table 3).
      Table 3MAP and SV at the Start of Fluid Intervention (t0) and Their Maximum Change Within 5 Minutes (n = 125 Fluid Interventions)
      ΔMAP ≥ 10%:ΔMAP < 10%:p
      Chi-square test for number of fluid interventions; clustered Wilcoxon rank-sum test for hemodynamic data.
       Number of fluid interventions, n (%)60 (48)65 (52)0.65
       MAP at t0, median (IQR), mmHg70 (65-75)75 (68-83)0.17
       Maximum MAP, median (IQR), mmHg82 (77-89)78 (72-85)0.04
       Maximum ΔMAP, median (IQR), in % of baseline MAP16% (12%-21%)5% (2%-8%)< 0.001
      ΔSV ≥ 10%:ΔSV < 10%:
       Number of fluid interventions, n (%)82 (66)43 (34)< 0.001
       SV at t0, median (IQR), mL68 (57-85)77 (71-90)0.09
       Maximum SV, median (IQR), mL83 (69-100)81 (73-95)0.88
       Maximum ΔSV, median (IQR), in % of baseline SV17% (13%-24%)6% (3%-7%)< 0.001
      Abbreviations: MAP, mean arterial pressure; SV, stroke volume.
      low asterisk Chi-square test for number of fluid interventions; clustered Wilcoxon rank-sum test for hemodynamic data.
      Eighty-two (66%) fluid interventions were SV-responsive, and 43 (34%) interventions were SV–non-responsive (Table 3). Maximum change in SV within 5 minutes was 17% (13-24%) and 6% (3-7%) in SV-responsive and SV–nonresponsive interventions, respectively (p < 0.001) (Table 3). The SV-responsive and SV–nonresponsive interventions had similar SV values at t0 (Table 3). Supplemental Table S1 shows all hemodynamic data at t0 in MAP or SV-responsive and SV–nonresponsive interventions. The greatest increases in MAP and SV were observed at minute 4 (3-5) (median [IQR]) in MAP- or SV-responsive interventions (Supplemental Figs S1 and S2). Fifty-three (65%) of 82 SV-responsive interventions showed an increase in MAP ≥10% (Fig 3).
      Fig 3
      Fig. 3Stroke volume (SV) and mean arterial pressure (MAP) responsiveness in 125 fluid interventions. Each arrow starts at the baseline SV and MAP value and ends at the maximum SV and MAP value within 5 minutes after the start of the fluid intervention. MAP, mean arterial pressure; SV, stroke volume.
      Seven (16%) of 43 SV–nonresponsive interventions showed an increase in MAP ≥10% (Fig 3).

      Additional Hemodynamic Predictors for MAP and SV Responsiveness in Fluid Interventions Performed if SVV ≥13%

      Among the hemodynamic variables assessed as potential predictors (Table 1), PPV and Edyn showed the lowest p values to predict both MAP and SV responsiveness (Supplemental Table S2).

      Comparison of Sensitivity and Specificity for Predicting MAP and SV Responsiveness When Using SVV Alone or Combined With PPV and Edyn

      As fluid interventions only were performed if SVV ≥13%, sensitivity of SVV alone was 1, and specificity was 0 in the authors’ study setting (Table 4). An additional PPV cut-off ≥17.1% would predict MAP responsiveness, with a sensitivity of 0.82 and specificity of 0.65, whereas an additional Edyn cut-off ≥1.1 would predict MAP responsiveness, with a sensitivity of 0.75 and a specificity of 0.71 (Table 4). Further increasing the PPV cut-off to ≥18.6% would predict SV responsiveness, with a sensitivity of 0.66 and specificity of 0.93, whereas an Edyn cut-off ≥1.0 would predict SV responsiveness, with a sensitivity of 0.71 and specificity of 0.74 (Table 4). If the PPV or Edyn cut-offs were additional triggers for fluid interventions, the number of non-responsive (marked in red, Table 4) fluid interventions would decrease, but some responsive interventions (marked in blue, Table 4) would not be performed anymore. The total number of non-responsive (marked in red, Table 4) and responsive but not-performed interventions (marked in blue, Table 4) when using PPV or Edyn in addition to SVV would be smaller than the number of non-responsive interventions when only using SVV (marked in red, Table 4).
      Table 4Number of Fluid Interventions Performed if SVV ≥13%, Number of Fluid Interventions That Would Have Been Performed if SVV ≥13% and PPV ≥ Cut-Off Value, and Number of Fluid Interventions that would have been performed if SVV ≥13% and Edyn ≥ Cut-Off Value (n = 125 fluid interventions)
      ΔMAP ≥10%ΔSV ≥10%
      YesNoYesNo
      Fluid given if SVV ≥13%Yes60 (48%)65 (52%)Fluid given if SVV ≥13%Yes82 (66%)43 (34%)
      No--No--
      Sens: 1Spec: 0Sens: 1Spec: 0
      Fluid given if SVV ≥13% and PPV ≥17%Yes49 (39%)23 (18%)Fluid given if SVV ≥13% and PPV ≥19%Yes54 (43%)3 (2%)
      No11 (9%)42 (34%)No28 (22%)40 (32%)
      Sens: 0.82Spec: 0.65Sens: 0.66Spec: 0.93
      Fluid given if SVV ≥13% and Edyn ≥1.1Yes45 (36%)19 (15%)Fluid given if SVV ≥13% and Edyn ≥1.0Yes58 (46%)11 (9%)
      No15 (12%)46 (37%)No24 (19%)32 (26%)
      Sens: 0.75Spec: 0.71Sens: 0.71Spec: 0.74
      NOTE. Non-responsive fluid interventions (would have been performed if SVV/PPV/Edyn ≥ cut-off, but no ΔMAP/SV ≥10%) are marked in red. Responsive, but not performed fluid interventions (would not have been performed if SVV/PPV/Edyn < cut-off, but ΔMAP/SV ≥10%) are marked in blue.
      Abbreviations: MAP, mean arterial pressure; Sens, sensitivity; Spec, specificity; SV, stroke volume; SVV, stroke volume variation.

      Accuracy of PPV and Edyn for MAP and SV Responsiveness in Fluid Interventions Performed if SVV ≥13%

      The AUROC of PPV and Edyn to predict MAP responsiveness were 0.79 and 0.75, respectively (Supplemental Fig S3). The AUROC of PPV and Edyn to predict SV responsiveness were 0.85 and 0.77, respectively (Supplemental Fig S3).

      Discussion

      Two-thirds of the fluid interventions performed if SVV ≥13% were SV-responsive, whereas only half of the fluid interventions were MAP-responsive. The addition of PPV and Edyn cut-off values to the SVV cut-off would decrease sensitivity from 1 to 0.66 to 0.82 and increase specificity from 0 to 0.65 to 0.93 for the prediction of MAP and SV responsiveness in the authors’ study setting. The additional predictors, PPV and Edyn, accurately predicted MAP and SV responsiveness with an AUROC between 0.75 and 0.85.

      MAP and SV Responsiveness in Fluid Interventions

      As mentioned previously, both SV and MAP are important targets in the hemodynamic management of anesthesiologists,
      • Molnar Z
      • Nemeth M.
      Monitoring of tissue oxygenation: An everyday clinical challenge.
      with SV that determines cardiac output being a surrogate parameter for oxygen delivery.
      • Lim HS.
      Cardiogenic Shock. Failure of oxygen delivery and oxygen utilization.
      ,
      • Dunn JOC
      • Mythen MG
      • Grocott MP.
      Physiology of oxygen transport.
      The MAP is directly related to the organ perfusion pressure.
      • Beloncle F
      • Piquilloud L
      • Asfar P.
      Renal Blood Flow and Perfusion Pressure.
      This is why the authors’ decided to consider both SV and MAP responsiveness as primary outcomes in this study.
      In this study, SVV ≥13% alone predicted SV responsiveness in two-thirds and MAP responsiveness in only one-half of the fluid interventions. In other studies, SVV ≥10% alone predicted SV responsiveness in 80%
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      and MAP responsiveness in only one-third
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      to two-thirds
      • García MIM
      • Cano AG
      • Romero MG.
      Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients.
      of all fluid interventions in patients during neurosurgical or abdominal surgery
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      or ICU patients.
      • García MIM
      • Cano AG
      • Romero MG.
      Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients.
      In this and in other trials, SVV alone could better predict SV than MAP responsiveness. The SVV is primarily a predictor for SV responsiveness.
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      These findings highlight the need for an additional predictor for MAP responsiveness in particular.

      Additional Predictors for MAP and SV Responsiveness in Fluid Interventions Performed if SVV ≥13%

      Among the assessed hemodynamic variables in the authors’ study, PPV and Edyn had the lowest p values in the models predicting MAP responsiveness. Both PPV and Edyn can be regarded as dynamic measures related to SVR.
      • García MIM
      • Cano AG
      • Romero MG.
      Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients.
      ,
      • Printz MP
      • Jaworski RL.
      Hypertension; overview.
      Interestingly, systemic vascular resistance or the systemic vascular resistance index could not predict MAP or SV responsiveness in this and other studies.
      • García MIM
      • Cano AG
      • Romero MG.
      Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients.
      ,
      • Guinot PG
      • Bernard E
      • Levrard M
      • et al.
      Dynamic arterial elastance predicts mean arterial pressure decrease associated with decreasing norepinephrine dosage in septic shock.
      Indeed, PPV and Edyn better reflect the dynamic elastic properties of the vascular wall compared to SVR, as they measure the specific variation over time. Edyn is defined as the ratio of PPV to SVV (Table 1) and describes the variation in pulse pressure for a given variation in SV during a respiratory cycle. In theory, the higher the variation in pulse pressure is compared to the variation in SV during a respiratory cycle, the greater should be the increase in MAP after a fluid bolus.
      • Zhou X
      • Pan W
      • Chen B
      • et al.
      Predictive performance of dynamic arterial elastance for arterial pressure response to fluid expansion in mechanically ventilated hypotensive adults: A systematic review and meta-analysis of observational studies.

      Comparison of Sensitivity and Specificity for Predicting MAP and SV Responsiveness When Using SVV Alone or Combined With PPV and Edyn

      The addition of PPV and Edyn cut-off values to the SVV cut-off would decrease sensitivity from 1 to 0.66 to 0.82 and would increase specificity from 0 to 0.65 to 0.93 for the prediction of MAP and SV responsiveness in the authors’ study setting. When using PPV or Edyn in combination with SVV, the sum of non-responsive and responsive but not performed interventions was lower than the number of non-responsive interventions when only using SVV (Table 4). The authors’ group previously showed that an active decision system only relying on SVV ≥13% without baseline fluid as indication for giving fluid was feasible and did not result in clinically significant fluid depletion or overload.
      • Menger J
      • Fischer A
      • Mouhieddine M
      • et al.
      Evaluation of an active decision support system for hemodynamic optimization during elective major vascular surgery.
      The authors now suggest adding PPV or Edyn as additional triggers for fluid interventions to further improve MAP and SV responsiveness.

      Accuracy of PPV and Edyn for MAP and SV Responsiveness in Fluid Interventions Performed if SVV ≥13%

      Both PPV and Edyn achieved good accuracy for predicting MAP responsiveness with an AUROC of 0.79 and 0.75 in the authors’ study. In other studies, Edyn >0.8911 or >0.6510 had an excellent accuracy for the prediction of MAP responsiveness (AUROC 0.99) in mechanically ventilated patients in the ICU who received fluid if SVV ≥10%.
      • García MIM
      • Cano AG
      • Romero MG.
      Dynamic arterial elastance to predict arterial pressure response to volume loading in preload-dependent patients.
      However, it only moderately predicted MAP responsiveness (AUROC 0.71) in patients during neurosurgical or abdominal surgery who received fluid if SVV ≥10%.
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      The authors’ data confirmed that SVV alone could already predict SV responsiveness in two-thirds of all fluid interventions. Consequently, there may be less need for an additional predictor for SV responsiveness as opposed to MAP responsiveness. Nevertheless, PPV and Edyn accurately predicted SV responsiveness with an AUROC of 0.85 and 0.77 in the authors’ study. Their results warrant the use of PPV or Edyn in addition to SVV to better predict MAP responsiveness in particular but also SV responsiveness.

      Limitations and Strengths

      Vasopressors lead to a higher preload by constricting the venous system.
      • Nakamoto S
      • Tatara T
      • Okamoto T
      • et al.
      Complex effects of continuous vasopressor infusion on fluid responsiveness during liver resection: A randomised controlled trial.
      Thus, vasopressors were shown to decrease SVV, PPV, and Edyn.
      • de Courson H
      • Boyer P
      • Grobost R
      • et al.
      Changes in dynamic arterial elastance induced by volume expansion and vasopressor in the operating room: A prospective bicentre study.
      ,
      • Monge García MI
      • Guijo González P
      • Gracia Romero M
      • et al.
      Effects of arterial load variations on dynamic arterial elastance: An experimental study.
      However, the study authors accounted for the administration of noradrenaline and dobutamine in the multivariable logistic regression models.
      The estimation of an optimal cut-off may be limited due to the small sample size in the authors’ study. Yet the proof-of-concept study showed that PPV and Edyn could predict MAP or SV responsiveness in vascular surgery patients with high SVV.
      To the best of the authors’ knowledge, their study was the first to compare SVV alone versus combined with Edyn or PPV to predict MAP or SV responsiveness in vascular surgery patients. Previous studies in vascular surgery patients performed fluid interventions according to clinical assessment and then assessed if SVV alone, PPV alone, or Edyn alone could predict MAP, SVI or CO fluid responsiveness.
      • Cannesson M
      • Le Manach Y
      • Hofer CK
      • et al.
      Assessing the diagnostic accuracy of pulse pressure variations for the prediction of fluid responsiveness: A “gray zone” approach.
      ,
      • Lanchon R
      • Nouette-Gaulain K
      • Stecken L
      • et al.
      Dynamic arterial elastance obtained using arterial signal does not predict an increase in arterial pressure after a volume expansion in the operating room.
      ,
      • Willars C
      • Dada A
      • Hughes T
      • et al.
      Functional haemodynamic monitoring: The value of SVV as measured by the LiDCORapid in predicting fluid responsiveness in high risk vascular surgical patients.

      Conclusion

      The addition of PPV and Edyn cut-off values to the SVV cut-off would decrease sensitivity from 1 to 0.66 to 0.82 and increase specificity from 0 to 0.65 to 0.93 regarding the prediction of MAP and SV responsiveness in the authors’ study setting. Both PPV and Edyn achieved proper accuracy for the prediction of MAP and SV responsiveness, with an AUROC between 0.75 and 0.85. Therefore, PPV or Edyn may be used in conjunction with SVV to better predict MAP and SV fluid responsiveness in patients undergoing major vascular surgery.

      Conflict of Interest

      None.

      Appendix. Supplementary materials

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