Value of variation of end-tidal carbon dioxide for predicting fluid responsiveness during the passive leg raising test in patients with mechanical ventilation: a systematic review and meta-analysis

Background The ability of end-tidal carbon dioxide (ΔEtCO2) for predicting fluid responsiveness has been extensively studied with conflicting results. This meta-analysis aimed to explore the value of ΔEtCO2 for predicting fluid responsiveness during the passive leg raising (PLR) test in patients with mechanical ventilation. Methods PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched up to November 2021. The diagnostic odds ratio (DOR), sensitivity, and specificity were calculated. The summary receiver operating characteristic curve was estimated, and the area under the curve (AUROC) was calculated. Q test and I2 statistics were used for study heterogeneity and publication bias was assessed by Deeks’ funnel plot asymmetry test. We performed meta-regression analysis for heterogeneity exploration and sensitivity analysis for the publication bias. Results Overall, six studies including 298 patients were included in this review, of whom 149 (50%) were fluid responsive. The cutoff values of ΔEtCO2 in four studies was 5%, one was 5.8% and the other one was an absolute increase 2 mmHg. Heterogeneity between studies was assessed with an overall Q = 4.098, I2 = 51%, and P = 0.064. The pooled sensitivity and specificity for the overall population were 0.79 (95% CI 0.72–0.85) and 0.90 (95% CI 0.77–0.96), respectively. The DOR was 35 (95% CI 12–107). The pooled AUROC was 0.81 (95% CI 0.77–0.84). On meta-regression analysis, the number of patients was sources of heterogeneity. The sensitivity analysis showed that the pooled DOR ranged from 21 to 140 and the pooled AUC ranged from 0.92 to 0.96 when one study was omitted. Conclusions Though the limited number of studies included and study heterogeneity, our meta-analysis confirmed that the ΔEtCO2 performed moderately in predicting fluid responsiveness during the PLR test in patients with mechanical ventilation.

The accuracy of Pleth Variability Index for directed fluid optimization in donors in living donor liver transplantation

Background Fluid management strongly affects hepatic resection and aims to reduce intraoperative bleeding during living donation. The Pleth Variability Index (PVI) is a tool to assess the fluid responsiveness from the pulse oximeter waveform; we evaluated the efficacy and accuracy of finger PVI compared to pulse pressure variation (PPV) from arterial waveform in predicting the fluid response in donor hepatectomy patients with the guide of non-invasive cardiac output (CO) measurements. We recruited forty patients who were candidates for right lobe hepatectomy for liver transplantation under conventional general anesthesia methods. During periods of intraoperative hypovolemia not affected by surgical manipulation, PVI, PPV, and CO were recorded then compared with definitive values after fluid bolus administration of 3–5 ml/kg aiming to give a 10% increase in CO which classified the patients into responders and non-responders. Results Both PPV and PVI showed a significant drop after fluid bolus dose (P < 0.001) leading to an increase of the CO (P < 0.0001), and the area under the curve was 0.934, 0.842 (95% confidence interval, 0.809 to 0.988, 0.692 to 0.938) and the standard error was 0.0336, 0.124, respectively. Pairwise comparison of PPV and PVI showed non-significant predictive value between the two variables (P = 0.4605); the difference between the two areas was 0.0921 (SE 0125 and 95% CI − 0.152 to 0.337). Conclusions PVI is an unreliable indicator for fluid response in low-risk donors undergoing right lobe hepatectomy compared to PPV. We need further studies with unbiased PVI monitors in order to implement a non-invasive and safe method for fluid responsiveness.

Slope analysis for the prediction of fluid responsiveness by a stepwise PEEP elevation recruitment maneuver in mechanically ventilated patients

Objective Assessment of fluid responsiveness is problematic in intensive care unit patients. Lung recruitment maneuvers (LRM) can be used as a functional test to predict fluid responsiveness. We propose a new test to predict fluid responsiveness in mechanically ventilated patients by analyzing the variations in central venous pressure (CVP) and systemic arterial parameters during a prolonged sigh breath LRM without the use of a cardiac output measuring device. Design Prospective observational cohort study. Setting Intensive Care Unit, Saint-Etienne University Central Hospital. Patients Patients under mechanical ventilation, equipped with invasive arterial blood pressure, CVP, pulse contour analysis (PICCO™), requiring volume expansion, with no right ventricular dysfunction. Interventions. None. Measurements and main results CVP, systemic arterial parameters and stroke volume (SV) were recorded during prolonged LRM followed by a 500 mL fluid expansion to asses fluid responsiveness. 25 patients were screened and 18 patients analyzed. 9 patients were responders to volume expansion and 9 were not. Evaluation of hemodynamic parameters suggested the use of a linear regression model. Slopes for systolic arterial pressure, pulse pressure (PP), CVP and SV were all significantly different between responders and non-responders during the pressure increase phase of LRM (STEP-UP) (p = 0.022, p = 0.014, p = 0.006 and p = 0.038, respectively). PP and CVP slopes during STEP-UP were strongly predictive of fluid responsiveness with an AUC of 0.926 (95% CI, 0.78 to 1.00), sensitivity = 100%, specificity = 89% and an AUC = 0.901 (95% CI, 0.76 to 1.00), sensibility = 78%, specificity = 100%, respectively. Combining sensitivity of PP and specificity of CVP, prediction of fluid responsiveness can be achieved with 100% sensitivity and 100% specificity (AUC = 0.96; 95% CI, 0.90 to 1.00). One patient showed inconclusive values using the grey zone approach (5.5%). Conclusions In patients under mechanical ventilation with no right heart dysfunction, the association of PP and CVP slope analysis during a prolonged sigh breath LRM seems to offer a very promising method for prediction of fluid responsiveness without the use and associated cost of a cardiac output measurement device. Trial registration NCT04304521, IRBN902018/CHUSTE. Registered 11 March 2020, Fluid responsiveness predicted by a stepwise PEEP elevation recruitment maneuver in mechanically ventilated patients (STEP-PEEP)

Diagnostic Accuracy of Ultrasonographic Respiratory Variation in the Inferior Vena Cava, Subclavian Vein, Internal Jugular Vein, and Femoral Vein Diameter to Predict Fluid Responsiveness: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to investigate the ultrasonographic variation of the diameter of the inferior vena cava (IVC), internal jugular vein (IJV), subclavian vein (SCV), and femoral vein (FV) to predict fluid responsiveness in critically ill patients. Relevant articles were obtained by searching PubMed, EMBASE, and Cochrane databases (articles up to 21 October 2021). The number of true positives, false positives, false negatives, and true negatives for the index test to predict fluid responsiveness was collected. We used a hierarchical summary receiver operating characteristics model and bivariate model for meta-analysis. Finally, 30 studies comprising 1719 patients were included in this review. The ultrasonographic variation of the IVC showed a pooled sensitivity and specificity of 0.75 and 0.83, respectively. The area under the receiver operating characteristics curve was 0.86. In the subgroup analysis, there was no difference between patients on mechanical ventilation and those breathing spontaneously. In terms of the IJV, SCV, and FV, meta-analysis was not conducted due to the limited number of studies. The ultrasonographic measurement of the variation in diameter of the IVC has a favorable diagnostic accuracy for predicting fluid responsiveness in critically ill patients. However, there was insufficient evidence in terms of the IJV, SCV, and FV.

Inferior vena cava collapsibility index as a predictor of fluid responsiveness in sepsis-related acute circulatory failure

Background Assessing fluid responsiveness is the key to successful resuscitation of critically-ill sepsis patients. The use of IVC variation is favored among the dynamic methods of fluid responsiveness assessment in the ICU because it is non-invasive and inexpensive; moreover, it does not demand a high level of training. The aim of this study is to determine the value of the IVC respiratory variability for predicting fluid responsiveness in spontaneously breathing sepsis patients with acute circulatory failure. Results In this prospective observational study, fifty-eight spontaneously breathing sepsis patients admitted in the ICU were enrolled after the approval of the departmental Research Ethical Committee, and the informed written consent had been taken from the patients. Ultrasonographic and echocardiographic parameters were measured “IVC parameters and stroke volume (SV)” with calculation of the inferior vena cava collapsibility index (IVCCI) and cardiac output. These values were obtained before (baseline) and after volume expansion with a fluid bolus. The study showed that twenty-nine patients (50%) were considered to be responders, with an increase in CO by 10% or more after fluid challenge. There was a significant difference between responders and non-responders in baseline IVCCI (p value < 0.001). There were no significant differences between responders and non-responders in terms of demographic and baseline clinical characteristics. Also, there was statistically significantly larger maximum (IVC max) and minimum (IVC min) inferior vena cava diameters before volume expansion in non-responders than in responders with p value 0.037 and 0.001 respectively. The suggested cut off value regarding baseline IVCCI to predict response to fluid infusion is 0.32 with a high chance of response above this figure (a sensitivity of 72.41% and a specificity of 82.76%). Conclusions Inferior vena cava collapsibility index assessment can be a sensitive and a good predictor of fluid responsiveness, being based on a safe and a non-invasive technique compared to other methods such as central venous pressure (CVP) measurement and pulmonary artery catheter insertion.