[The value of changes in end-tidal carbon dioxide pressure induced by passive leg raising test in predicting fluid responsiveness in mechanically ventilated patients with septic shock].

To test whether the changes of partial end-tidal carbon dioxide pressure (PETCO2) during passive leg raising (PLR) predict fluid responsiveness in mechanically ventilated patients with septic shock.Forty-two mechanically ventilated patients with septic shock admitted from January 2012 to November 2012 were prospectively recruited.Hemodynamic parameters monitored by a pulse indicator continuous cardiac output (PiCCO) device and PETCO2 monitored by an expiratory-CO2 device were studied at baseline, after PLR, and after volume expansion. Fluid responsiveness was defined as an increase in cardiac index (CI) of 15% or greater after volume expansion. The correlation between PLR-induced CI change (ΔCIPLR) and PETCO2 (ΔPETCO2-PLR) was analyzed. The value of ΔPETCO2-PLR to predict fluid responsiveness was evaluated by receiver operating characteristic (ROC) curves.A total of 42 patients were enrolled in this study, of whom, 24 had a CI increase of ≥ 15% after volume expansion (responders). After PLR, CI and PETCO2 were both significantly increased in the response group compared with baseline [(21.4 ± 12.9)% of CI and (9.6 ± 4.7)% of PETCO2, P < 0.05], while no significant changes were observed (P > 0.05) in the non-response group. Both ΔCIPLR and ΔPETCO2-PLR were significantly higher in responder group than in the non-responder group (both P < 0.05). ΔCI and ΔPETCO2 after PLR were strongly correlated (r = 0.64, P < 0.05). In responders after PLR, the area under ROC curve of ΔPETCO2-PLR was 0.900 ± 0.056 (95%CI 0.775-1.000, P < 0.05). An increase of ≥ 5% in ΔPETCO2-PLR predicted fluid responsiveness with a sensitivity of 88.0% and specificity of 88.2%.The change of PETCO2 induced by passive leg raising is a non-invasive and easy way to predict fluid responsiveness in mechanically ventilated patients with septic shock.