Background: The variation of end-tidal carbon dioxide(ΔEtCO2) has have been extensively studied with respect to its value in predicting fluid responsiveness, but the results are conflicting. 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. We performed meta-regression analysis for heterogeneity exploration and sensitivity analysis for the publication bias.
Results: Overall, 298 patients were included in this review, of whom 149 (50%) were fluid responsive. The cutoff values of ΔEtCO2 varied across studies, ranging from 5% to 5.8% or absolute increase 2mmHg. 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) (Fig. 4). 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: This study was the first meta-analysis to evaluate the diagnostic accuracy of ΔEtCO2 in predicting fluid responsiveness during PLR test in patients with mechanical ventilation. This study confirmed that the ΔEtCO2 performed well in predicting fluid responsiveness in patients with mechanical ventilation.