Diaphragm Dysfunction After Cardiac Surgery: Reappraisal.

OBJECTIVES: The aim of this study was to re-investigate the incidence, risk factors, and outcomes of postoperative diaphragmatic dysfunction (DD) with actual cardiac surgery procedures. DESIGN: Single-center, retrospective, observational study based on a prospectively collected database. SETTING: Tertiary care cardiac surgery center. PARTICIPANTS: Patients who underwent cardiac surgery between January 2016 and September 2019. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The DD group included patients with clinically perceptible diaphragmatic paralysis, which was confirmed by chest ultrasound (amplitude of the diaphragm movement in time-motion mode at rest, after a sniff test). The primary endpoint was the incidence of DD. Among 3,577 patients included, the authors found 272 cases of DD (7.6%). Individuals with DD had more arterial hypertension (64.3% v 52.6%; p < 0.0001), higher body mass index (BMI) (28 [25-30] kg/m2v 26 [24-29] kg/m2; p < 0.0002), and higher incidence of coronary bypass grafting (CABG) (58.8% v 46.6%; p = 0.0001). DD was associated with more postoperative pneumonia (23.9% v 8.7%; p < 0.0001), reintubation (8.8% v 2.9%; p < 0.0001), tracheotomy (3.3% v 0.3%; p < 0.0001), noninvasive ventilation (45.6% v 5.4%; p < 0.0001), duration of mechanical ventilation (five [four-11] hours v four [three-six] hours; p < 0.0001), and intensive care unit and hospital stays (14 [11-17] days v 13 [11-16] days; p < 0.0001). In multivariate analysis, DD was associated with CABG (odds ratio [OR] 1.9 [1.5-2.6]; p = 0.0001), arterial hypertension (OR 1.4 [1.1-1.9]; p = 0.008), and BMI (OR per point 1.04 [1.01-1.07] kg/m2; p = 0.003). CONCLUSIONS: The incidence of symptomatic DD after cardiac surgery was 7.6%, leading to respiratory complications and increased ICU stay. CABG was the principal factor associated with DD.

Takotsubo cardiomyopathy after cardiac surgery: A case-series and systematic review of literature.

Background: Takotsubo cardiomyopathy (TTC) is a rare entity after cardiac surgery. Aims: To describe patients' profile who developed postoperative TTC after cardiac surgery, management, and outcomes. Methods: We performed a systematic literature search to extract cases of TTC after adult cardiac surgery (from 1990 to 2021). Additionally, we extracted all cases of TTC in a prospective single-center cohort database of 10,000+ patients (from 2007 to 2019). We then combined all cases in a single cohort to describe its clinical features. Results: From 694 screened articles, we retained 71 individual cases published in 20 distinct articles (19 cases reports and 1 case-series). We combined these to 10 cases extracted from our cohort [among 10,682 patients (0.09%)]. Overall, we included 81 cases. Patients were aged 68 ± 10 years-old and 64/81 (79%) were women. Surgery procedures included mitral valve and/or tricuspid valve surgery in 70/81, 86%. TTC was diagnosed in the first days after surgery [median 4 (1-4) days]. Incidence of cardiogenic shock, defined as requirement of vasopressor and/or inotropic support was 24/29, 83% (data available on 29/81 patients). Refractory cardiogenic appeared in 5/81, 6% who required implantation of arterio-venous extra-corporeal membrane oxygenation, and 6/81, 7%, intra-aortic balloon pump. In-hospital mortality was 5/81, 6%. Conclusion: This systematic review, based on case reports and case series, showed that postoperative TTC appears as a rare complication after cardiac surgery and mainly occurred after mitral and/or tricuspid valve repair procedures. In this population, TTC is associated with high rate of cardiogenic shock.

Use of Almitrine and Inhaled Nitric Oxide in ARDS Due to COVID-19.

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is manifested by an acute respiratory distress syndrome (ARDS) with intense inflammation and endothelial dysfunction leading to particularly severe hypoxemia. We hypothesized that an impaired hypoxic pulmonary vasoconstriction aggravates hypoxemia. The objective of the study was to test the effect of two pulmonary vasoactive drugs on patient oxygenation. Methods: Observational, single-center, open-label study in one intensive care unit (ICU) of the Paris area, realized in April 2020. Eligible patients had coronavirus disease 2019 (COVID-19) and moderate to severe ARDS [arterial partial pressure of oxygen/fraction of inspired oxygen (PaO2/FiO2) <200 mmHg] despite conventional protective ventilation. Exclusion criteria included pulmonary artery hypertension defined by a pulmonary artery systolic pressure (PAPs) >45 mmHg. The assessment of oxygenation was based on PaO2/FiO2 at (1) baseline, then after (2) 30 min of inhaled nitric oxide (iNO) 10 ppm alone, then (3) 30 min combination of iNO + almitrine infusion 8 µg/kg/min, then (4) 30 min of almitrine infusion alone. Results: Among 20 patients requiring mechanical ventilation during the study period, 12 met the inclusion criteria. Baseline PaO2/FiO2 was 146 ± 48 mmHg. When iNO was combined with almitrine, PaO2/FiO2 rose to 255 ± 90 mmHg (+80 ± 49%, p = 0.005), also after almitrine alone: 238 ± 98 mmHg (+67 ± 75%, p = 0.02), but not after iNO alone: 185 ± 73 mmHg (+30 ± 5%, p = 0.49). No adverse events related to almitrine infusion or iNO was observed. Conclusion: Combining iNO and infused almitrine improved the short-term oxygenation in patients with COVID-19-related ARDS. This combination may be of interest when first-line therapies fail to restore adequate oxygenation. These findings argue for an impaired pulmonary hypoxic vasoconstriction in these patients.

Post-operative Right Ventricular Failure After Cardiac Surgery: A Cohort Study.

Introduction: Right ventricular failure (RVF) after cardiac surgery is an important risk factor for morbidity and mortality. Its diagnosis is challenging, and thus, its incidence and predictors are not well-established. We investigated the incidence, complications, and variables associated with clinically relevant post-operative RVF. Methods: We included all patients who underwent cardiac surgery with cardiopulmonary bypass between 2016 and 2019 in a cardiac surgery center with standardized diagnostic and therapeutic management of RVF. RVF was considered only if clinically relevant: associated with hemodynamic instability requiring catecholamine support and inhaled nitric oxide relayed by sildenafil. Results: Overall, 3,826 patients were included, of whom, 110 (2.9%) developed post-operative RVF. Mortality was not different among patients who developed post-operative RVF, compared with the rest of the cohort (1.8 vs. 0.7%, p = 0.17). Using a composite outcome that combined death, reintubation, stroke, and prolonged intensive care unit stay (more than 14 days) yielded an incidence of 6.6%, and RVF was associated with this composite outcome with an odds ratio of 3.6 (2.2-5.8), p < 0.001. In a multivariable model, pre-operative variables independently associated with post-operative RVF were pre-operative atrial fibrillation (AF) {adjusted odds ratio (adjOR) 3.22 [95% confidence interval (95%CI) = 1.94-5.36], p < 0.001}, left ventricle ejection fraction below 50% [adjOR = 2.55 (95%CI = 1.52-4.33), p < 0.001], systolic pulmonary artery pressure above 55 mmHg [adjOR = 8.64 (95%CI = 5.27-14.1); p < 0.001], mitral valve surgery [adjOR = 2.17 CI (95%CI = 1.28-3.66), p = 0.004], and tricuspid valve surgery [adjOR = 10.33 (95%CI = 6.14-17.4), p < 0.001]. In patients who developed post-operative RVF requiring treatment, 32 (29.1%) showed RV dysfunction before surgery. Conclusion: In this cohort study, 2.9% of patients developed clinically significant post-operative RVF. Moreover, RVF was associated with severe adverse outcomes, including death, strokes, reintubation, and prolonged intensive care unit stay.

Performance of EuroSCORE II and Society of Thoracic Surgeons risk scores in elderly patients undergoing aortic valve replacement surgery.

BACKGROUND: In cardiac surgery, risk is estimated with models such as EuroSCORE II and the Society of Thoracic Surgeons (STS) score. Performance of these scores may vary across various patient age ranges. AIM: To assess the effect of patient age on performance of the EuroSCORE II and STS scores, regarding postoperative mortality after surgical aortic valve replacement. METHODS: In a prospective cohort of patients, we assessed risk stratification of EuroSCORE II and STS scores for discrimination of in-hospital mortality with the area under the receiver operating characteristic curve (AUROC) and calibration with the Hosmer-Lemeshow test. Two groups of patients were compared: elderly (aged>75years) and younger patients. RESULTS: Of 1229 patients included, 635 (51.7%) were elderly. Mean EuroSCORE II score was 3.7±4.4% and mean STS score was 2.1±1.5%. Overall in-hospital mortality was 4.8% and was higher in the elderly compared with younger patients (6.6% vs. 2.8%; log-rank P=0.014). AUROC for the EuroSCORE II score was lower in elderly than in younger patients (0.731 vs. 0.784; P=0.025). Similarly, AUROC for the STS score was lower in elderly versus younger patients (0.738 vs. 0.768; P=0.017). In elderly patients, EuroSCORE II and STS scores were not adequately calibrated and significantly underestimated mortality. Age was independently associated with mortality, regardless of EuroSCORE II or STS score. CONCLUSIONS: In this cohort, EuroSCORE II and STS scores did not perform as well in elderly patients as in younger patients. Elderly patients may be at increased postoperative risk, regardless of risk score.

Low Tidal Volume Mechanical Ventilation Against No Ventilation During Cardiopulmonary Bypass in Heart Surgery (MECANO): A Randomized Controlled Trial.

BACKGROUND: Postoperative pulmonary complications are common after cardiac surgery and have been related to lung collapse during cardiopulmonary bypass (CPB). No consensus exists regarding the effects of maintaining mechanical ventilation during CPB to decrease these complications. RESEARCH QUESTION: To determine whether maintaining low-tidal ventilation (3 mL/kg 5 times/min, with positive end expiratory pressure of 5 cm H2O) during CPB (ventilation strategy) was superior to a resting-lung strategy with no ventilation (no ventilation strategy) regarding postoperative pulmonary complications, including mortality. STUDY DESIGN AND METHODS: In a randomized controlled trial, patients undergoing cardiac surgery at a single center from May 2017 through August 2019 were randomized to the ventilation or no ventilation strategy during CPB (1:1 ratio). Apart from the CPB phase, perioperative ventilation procedures were standardized. RESULTS: The study included 1,501 patients (mean age, 68.8 ± 10.3 years; 1,152 (76.7%) men; mean EuroSCORE II, 2.3 ± 2.7). Seven hundred fifty-six patients were in the ventilation strategy group, and no differences existed in baseline characteristics and types of procedures between the two groups. An intention-to-treat analysis yielded no significant difference between the ventilation and no ventilation groups regarding incidence of the primary composite outcome combining death, early respiratory failure, ventilation support beyond day 2, and reintubation, with 112 of 756 patients (14.8%) in the ventilation group vs 133 of 745 patients (17.9%) in the no ventilation group (OR, 0.80; 95% CI, 0.61-1.05; P = .11). Strict per-protocol analyses of 1,338 patients (89.1%) with equally distributed preoperative characteristics yielded similar results (OR, 0.81; 95% CI, 0.60-1.09; P = .16). Post hoc analysis of the subgroup who underwent isolated coronary artery bypass graft procedures (n = 725) showed that the ventilation strategy was superior to the no ventilation strategy regarding the primary outcome (OR, 0.56; 95% CI, 0.37-0.84; P = .005). INTERPRETATION: Among patients undergoing cardiac surgery with CPB, continuation of low tidal volume ventilation was not superior to no ventilation during CPB with respect to postoperative complications, including death, early respiratory failure, ventilation support beyond day 2, and reintubation. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT03098524; URL: www.clinicaltrials.gov.

Effect of BNP on risk assessment in cardiac surgery patients, in addition to EuroScore II.

Patients' prognostication around cardiac surgery is key to better assess risk-benefit balance. Preoperative brain natriuretic peptide (BNP) biomarker has been associated with mortality after cardiac surgery, but its added value with EuroScore 2 remains to be confirmed. In a prospective registry cohort of 4,980 patients undergoing cardiac surgery, the prognostic performance of EuroScore 2 and preoperative BNP was assessed regarding postoperative in-hospital mortality. Discrimination feature was evaluated using receiver-operator-characteristics analysis with area under curve (AUROC). Calibration feature was assessed using Hosmer-Lemeshow test. Multivariable analysis was performed to assess the association between covariates and in-hospital mortality. In-hospital mortality was 3.7%. The AUROC of EuroScore 2 was 0.82 (95% confidence interval (95%CI) 0.79-0.85, p < 0.0001). The AUROC of BNP was 0.66 (95%CI 0.62-0.70, p < 0.0001). The combined model with an AUROC of 0.67 (95%CI 0.63-0.71, p = 0.0001) did not yield better AUROC than EuroScore 2 alone (p < 0.0001 in disfavor of the combined model), nor BNP alone (p = 0.79). In multivariable analysis, EuroScore 2 remained independently associated with mortality (adj.OR of 1.12 (1.10-1.14), p < 0.0001), but BNP was not. Preoperative BNP was not an independent risk factor of postoperative mortality and did not add prognostic information, as compared to EuroScore 2 alone.Clinical trial registry Registry for the Improvement of Postoperative OutcomeS in Cardiac and Thoracic surgEry (RIPOSTE) database (NCT03209674).

Pacemaker implantation after aortic valve replacement: rapid-deployment Intuity® compared to conventional bioprostheses.

OBJECTIVES: The aim of this study was to compare the incidence of permanent pacemaker (PPM) implantation after aortic valve replacement by rapid-deployment bioprosthesis (RDB) and standard valve (Standard). METHODS: All patients undergoing aortic valve replacement between 2015 and 2018, in 1 centre, were included. A multivariate analysis on the whole cohort and then a propensity score matching were used to compare the 2 groups. The primary end point was PPM implantation. RESULTS: We studied 924 patients (256 RDBs and 668 Standards). Overall, 67 PPM were implanted, 37 (14.5%) in the RDB group and 26 (3.9%) in the Standard group (P < 0.0001, univariate analysis). The multivariate analysis in the unmatched population found 4 independent factors associated with PPM implantation: right bundle branch block with odds ratios (ORs 3.7, 95% CI 2.9-6.7; P < 0.0001), RDB (OR 3.6, 95% CI 2.0-6.2; P < 0.0001), age (OR 1.1, 95% CI 1.0-1.1; P < 0.006) and endocarditis (OR 3.4, 95% CI 1.0-11.0; P < 0.04). In the propensity score-matched RDB group (203 patients per group), 25 patients required PPM implantation versus 3 in the Standard group (12.3% vs 1.5%, P < 0.0001). RDBs also had more postoperative left bundle branch block and new onset of atrial fibrillation (30.2% vs 5.1%, P < 0.0001 and 34.0% vs 24.1%, P = 0.029). RDBs had lower operating times (in min): aortic cross-clamping = 62 (44-76.5) vs 72 (57.5-91.5) and cardiopulmonary bypass = 81 (63-98.5) vs 91 (75-112), P < 0.0001. There was no significant difference in other outcomes. CONCLUSIONS: RDBs were associated with reduced operating times, increased risk of atrial fibrillation and PPM implantation as compared with standard aortic valves.

Comparison of monitoring performance of Bioreactance vs. pulse contour during lung recruitment maneuvers.

INTRODUCTION: This study was designed to test the hypothesis of equivalence in cardiac output (CO) and stroke volume (SV) monitoring capabilities of two devices: non invasive transthoracic bioreactance (NICOM), and a pulse contour analysis (PICCO PC) coupled to transpulmonary thermodilution (PICCO TD). METHODS: We included consecutive patients of a single ICU following cardiac surgery. Continuous minute-by-minute hemodynamic variables obtained from NICOM and PICCO PC were recorded and compared in 20 patients at baseline, during a lung recruitment maneuver (20 cmH2O of PEEP) and following withdrawal of PEEP. PICCO TD measurements were also determined. We evaluated the accuracy of these two technologies at baseline using PICCO TD as reference and we estimated the precision by the fluctuation around the mean value (2SD/mean). Then, we assessed time response, amplitude response and reliability for detecting expected decreases when PEEP was applied. Type I and type II errors were analyzed. RESULTS: CO values (PICCO TD) ranged from 1.6 to 8.0 L.min-1. At baseline, CO values were comparable for NICOM, PICCO PC and PICCO TD: 5.0 +/- 1.2, 4.7 +/- 1.4 and 4.6 +/- 1.3 L.min.-1, respectively (NS). Limits of agreements with PICCO TD were 1.52 L.min.-1 for NICOM and 1.77 L.min.-1 for PICCO PC, NS. The 95% statistical power gives an equivalence with a threshold of 0.52 L.min.-1 for NICOM vs. PICCO PC. The CO precision was 6 +/- 3% and 6 +/- 5% for NICOM and PICCO PC, respectively, NS. When PEEP was applied, CO was reduced by 33 +/- 12%, 31 +/- 14% and 32 +/- 13%, for NICOM, PICCO PC and PICCO TD, respectively (NS). Time response was 3.2 +/- 0.7 minute for NICOM vs. 2 +/- 0.5 minute for PICCO PC (NS). SV results were comparable to those for CO. CONCLUSIONS: Although limited to 20 patients, this study has enough power to show comparable CO and SV monitoring capabilities of Bioreactance and pulse contour analysis calibrated by transpulmonary thermodilution.

Heart failure with preserved ejection fraction as an independent risk factor of mortality after cardiothoracic surgery.

BACKGROUND: The prognostic role of heart failure with preserved ejection fraction (HFpEF) remains unclear. This study aimed to assess HFpEF prognostic value after cardiothoracic surgery, adjusting for European System for Cardiac Operative Risk (EuroSCORE II) criteria. METHODS: Patients with left ventricular ejection fraction (LVEF) ≥ 50% undergoing cardiothoracic surgery between 2012 and 2016 were included. Patients with HFpEF were compared to control patients with LVEF ≥ 50%. HFpEF was defined following 2016 European Society of Cardiology guidelines: LVEF ≥ 50%, symptomatic HF with New York Heart Association (NYHA) class 2 or greater, elevated brain natriuretic peptide (BNP) and relevant echocardiographic findings (LV hypertrophy, LA enlargement, or diastolic filling anomaly). The primary endpoint was in-hospital mortality, and the secondary endpoint was postoperative shock. Multivariate analyses were performed to determine mortality and shock risk-factors. RESULTS: Among 1743 patients, 427 (24.5%) presented HFpEF. HFpEF was highly associated with in-hospital mortality (hazard ratio = 1.86; 95% confidence interval [CI], 1.16-2.98; P = .01). This association remained independent when adjusting for EuroSCORE II (adjusted hazard ratio = 1.6; 95% CI, 1.0-2.6; P = .049). Postoperative shock occurred more in HFpEF than in control patients (17.8% vs 6.7%; P < .001). HFpEF was an independent risk factor of postoperative shock (adjusted odds ratio = 2.9; 95% CI, 1.5-3.0; P < .001). CONCLUSIONS: HFpEF was an independent risk-factor of mortality and postoperative shock after cardiothoracic surgery, after adjustment regarding EuroSCORE II.

Noninvasive cardiac output monitoring (NICOM): a clinical validation.

OBJECTIVE: To evaluate the clinical utility of a new device for continuous noninvasive cardiac output monitoring (NICOM) based on chest bio-reactance compared with cardiac output measured semi-continuously by thermodilution using a pulmonary artery catheter (PAC-CCO). DESIGN: Prospective, single-center study. SETTING: Intensive care unit. PATIENTS: Consecutive adult patients immediately after cardiac surgery. INTERVENTIONS: Cardiac output measurements obtained from NICOM and thermodilution were simultaneously recorded minute by minute and compared in 110 patients. We evaluated the accuracy, precision, responsiveness, and reliability of NICOM for detecting cardiac output changes. Tolerance for each of these parameters was specified prospectively. MEASUREMENTS AND RESULTS: A total of 65,888 pairs of cardiac output measurements were collected. Mean reference values for cardiac output ranged from 2.79 to 9.27 l/min. During periods of stable PAC-CCO (slope<+/-10%, 2SD/mean<20%), the correlation between NICOM and thermodilution was R=0.82; bias was +0.16+/-0.52 l/min (+4.0+/-11.3%), and relative error was 9.1%+/-7.8%. In 85% of patients the relative error was <20%. During periods of increasing output, slopes were similar with the two methods in 96% of patients and intra-class correlation was positive in 96%. Corresponding values during periods of decreasing output were 90% and 84%, respectively. Precision was always better with NICOM than with thermodilution. During hemodynamic challenges, changes were 3.1+/-3.8 min faster with NICOM (p<0.01) and amplitude of changes did not differ significantly. Finally, sensitivity of the NICOM for detecting significant directional changes was 93% and specificity was 93%. CONCLUSION: Cardiac output measured by NICOM had most often acceptable accuracy, precision, and responsiveness in a wide range of circulatory situations.

Frequency of Recovery from Complete Atrioventricular Block After Cardiac Surgery.

Best timing for permanent pacemaker implantation to treat complete atrioventricular block (AVB) after cardiac surgery is unclear, as late pacemaker dependency was found low in recent observational studies. This study aimed to identify factors associated with spontaneous recovery from AVB. In a prospective and observational cohort, all patients who underwent cardiothoracic surgery during a 14-month-period were included (n = 1,200). Risk factors of postoperative AVB were assessed by logistic regression. Among patients who developed AVB, variables associated with recovery from AVB were assessed by Cox and logistic regression. Overall incidence of postoperative AVB was 6.0%. Risk factors of AVB were age (OR 1.03 [1.00 to 1.06], p = 0.023); female gender (OR 2.06 [1.24 to 3.41], p = 0.005), active endocarditis (OR 3.31 [1.33 to 8.26], p = 0.01), and aortic valve replacement (OR 3.17 [1.92 to 5.25], p <0.001). Among aortic valve replacement, sutureless aortic valve replacement was associated with more AVB (26.7% vs 8.1%, p <0.01). Recovery from AVB occurred in 30 patients (41.7%) in a median period of 3 days [interquartile range = 1;5]. Among patients who would recover from AVB, 90% of patients did so before day 7. None of the studied variable was independently associated with recovery from AVB. In conclusion, identified risk factors of postoperative AVB after cardiac surgery were age, female gender, endocarditis, and aortic valve replacement. Because most patients who would recover did so before day 7, this study validates modern guidelines suggesting permanent pacemaker implantation on day 7.

Low tidal volume mechanical ventilation against no ventilation during cardiopulmonary bypass heart surgery (MECANO): study protocol for a randomized controlled trial.

BACKGROUND: Postoperative pulmonary complications are a leading cause of morbidity and mortality after cardiac surgery. There are no recommendations on mechanical ventilation associated with cardiopulmonary bypass (CPB) during surgery and anesthesiologists perform either no ventilation (noV) at all during CPB or maintain low tidal volume (LTV) ventilation. Indirect evidence points towards better pulmonary outcomes when LTV is performed but no large-scale prospective trial has yet been published in cardiac surgery. DESIGN: The MECANO trial is a single-center, double-blind, randomized, controlled trial comparing two mechanical ventilation strategies, noV and LTV, during cardiac surgery with CPB. In total, 1500 patients are expected to be included, without any restrictions. They will be randomized between noV and LTV on a 1:1 ratio. The noV group will receive no ventilation during CPB. The LTV group will receive 5 breaths/minute with a tidal volume of 3 mL/kg and positive end-expiratory pressure of 5 cmH2O. The primary endpoint will be a composite of all-cause mortality, early respiratory failure defined as a ratio of partial pressure of oxygen/fraction of inspired oxygen <200 mmHg at 1 hour after arrival in the ICU, heavy oxygenation support (defined as a patient requiring either non-invasive ventilation, mechanical ventilation or high-flow oxygen) at 2 days after arrival in the ICU or ventilator-acquired pneumonia defined by the Center of Disease Control. Lung recruitment maneuvers will be performed in the noV and LTV groups at the end of surgery and at arrival in ICU with an insufflation at +30 cmH20 for 5 seconds. Secondary endpoints are those composing the primary endpoint with the addition of pneumothorax, CPB duration, quantity of postoperative bleeding, red blood cell transfusions, revision surgery requirements, length of stay in the ICU and in the hospital and total hospitalization costs. Patients will be followed until hospital discharge. DISCUSSION: The MECANO trial is the first of its kind to compare in a double-blind design, a no-ventilation to a low-tidal volume strategy for mechanical ventilation during cardiac surgery with CPB, with a primary composite outcome including death, respiratory failure and postoperative pneumonia. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03098524 . Registered on 27 February 2017.

Fluid responsiveness predicted by noninvasive bioreactance-based passive leg raise test.

PURPOSE: To study the feasibility of predicting fluid responsiveness (FR) by passive leg raising (PLR) using a Bioreactance-based noninvasive cardiac output monitoring device (NICOM). METHOD: This prospective, two-center study included 75 consecutive intensive care unit (ICU) adult patients immediately after cardiac surgery. NICOM was used to continuously record cardiac output (CO) at baseline, during a PLR, and then during a 500 ml i.v. rapid colloid infusion. We estimated the precision of NICOM at baseline to derive the least minimum significant change (LMSC) in CO. We studied the predictability of PLR for FR by systematic analysis of different categorizations of PLR and FR, based on percentage change in CO (from 0 to 20%). RESULTS: The LMSC was 8.85%. CO was 4.17 ± 1.04 L min⁻¹ at baseline, 4.38 ± 1.14 L min⁻¹ during PLR, 4.16 ± 1.08 L min⁻¹ upon return to baseline, and 4.85 ± 1.41 L min⁻¹ after fluid infusion. The change in CO following fluid bolus was highly correlated with the change in CO following PLR: y = 0.91x + 4.3, r = 0.77. The Pearson correlation coefficient showed that the best pair of thresholds was found for PLR ≥ 0% predicting FR ≥ 0%. Using this pair of thresholds, PLR had 88% sensitivity and 100% specificity for predicting FR. When we restricted the analysis to change in CO > LMSC, the best pair of thresholds was obtained for PLR > 9% predicting FR > 9%. Using this pair of thresholds, PLR sensitivity was reduced to 68% and specificity to 95%. CONCLUSIONS: In this specific population of patients, it is clinically valid to use the bioreactance-based NICOM system to predict FR from changes in CO during PLR.