Abstract
BackgroundThe 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.MethodsPubMed, 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.ResultsOverall, 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.ConclusionsThough 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.
Highlights
Fluid resuscitation is recommended and widely used as the first-line resuscitative therapy for all patients presenting with acute circulatory failure [1]
Search strategy Relevant studies up to November 2021 were searched in the PubMed, Embase, and Cochrane Library databases with the following terms and their combinations: “fluid therapy OR fluid responsive OR volume responsive,” “end tidal carbon dioxide OR end-tidal carbon dioxide OR End-tidal carbon dioxide (EtCO2)” and “mechanical ventilation OR ventilated.”
Selection criteria The inclusion criteria were as follows: (1) studies on patients receiving mechanical ventilation; (2) studies with passive leg raising (PLR)-induced increase in EtCO2 as the index test; (3) studies with a CO monitoring for the diagnosis of fluid responsiveness; (4) studies published with full-text in any language; (5) studies providing sufficient data for constructing 2-by-2 tables, including true positive (TP), false positive (FP), true negative (TN), and false negative (FN)
Summary
Fluid resuscitation is recommended and widely used as the first-line resuscitative therapy for all patients presenting with acute circulatory failure [1]. The traditional static parameters, such as intrathoracic blood volume index, pulmonary wedge pressure, and central venous pressure, have been proved not related to patient volume status [5, 6]. Hemodynamic parameters, such as pulse pressure variation and stroke volume variation, may better predict fluid responsiveness. 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
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