[The value of end-tidal carbon dioxide partial pressure combined passive leg raising test on volume responsiveness assessment in shocked patients post cardiac operation]

Abstract

Objective: To assess the value of end-tidal carbon dioxide partial pressure (PETCO2) combined passive leg raising (PLR) test on volume responsiveness assessment in shocked patients post cardiac operation.

Methods: A prospective, self-controlled, and observational study was conducted. The shocked patients post cardiac operation undergoing complete mechanical ventilation admitted to Department of Critical Care Medicine of First Affiliated Hospital of College of Medicine, Zhejiang University from June 2014 to October 2015 were enrolled.PETCO2 and hemodynamic parameters including stroke volume variation (SVV),cardiac index (CI),mean arterial pressure (MAP) monitored by a pulse indicator continuous cardiac output (PiCCO) were determined before and after PLR and volume expansion (VE).Volume responsiveness was defined as an increase in CI (△ CI) of 15％ or greater after VE, namely response group (△ CI ≥ 15％) and non-response group (△ CI ＜ 15％).The value of PLR-induced PETCO2 change (△PETCO2 PLH) to predict volume responsiveness was evaluated by receiver operating. characteristic curves (ROC).

Results: Among the 41 patients enrolled,21 had volume responsiveness (response group),and 20 had no responsiveness (non-response group).After PLR, the changes in CI and PETCO2 were both significantly increased in the response group compared with non-response group [△ CI:(13.5 ± 4.6)％ vs.(3.6± 3.5)％,△ PETCO2:(7.4 ± 3.4)％ vs.(2.8 ± 2.5)％,both P ＜ 0.05].△ PETCO2 PLR and baseline SVV were positively correlated with PLR-induced CI change (△ CI PLR) (r1 =0.50,r2 =0.38,both P ＜ 0.05).VE-induced PETCO2 change (△ PETCO2 VE),baseline SVV and △ CI PLR were positively correlated with VE-induced CI (△ CI VE) (r1 =0.58,r2 =0.56 and r3 =0.84,all P ＜ 0.01).The area under ROC curve (AUC) of △ PETCO2 PLR was 0.875±0.054 [95％ confidence interval (95％CI) =0.769-0.981,P ＜ 0.05].△ PETCO2 PLR ≥ 5.8％ predicted volume responsiveness with sensitivity of 76.2％ and specificity of 90.0％.AUC of △CI PLR was 0.933±0.036 (95％CI =0.862-1.000,P ＜ 0.05).△CI PLR ≥ 10.4％ predicted volume responsiveness with sensitivity of 81.0％ and specificity of 90.0％.AUC of baseline SVV was 0.831 ±0.066 (95％CI =0.702-0.960,P ＜ 0.05).Baseline SVV ≥ 12.5％ predicted volume responsiveness with sensitivity of 85.7％ and specificity of 75.0％.

Conclusion: The change in PETCO2 induced by PLR is a convenient, reliable and non-invasive indicator to predict volume responsiveness in shocked patients post cardiac operation with mechanical ventilation.