Evaluation of end-tidal carbon dioxide gradient as a predictor of volume responsiveness in spontaneously breathing healthy adults.

ABSTRACT:

Background

Methods to guide fluid therapy in spontaneously breathing patients are scarce. No studies have reported the accuracy of end-tidal CO₂ (ET-CO₂) to predict volume responsiveness in these patients. We sought to evaluate the ET-CO₂ gradient (?ET-CO₂) after a passive leg rise (PLR) maneuver to predict volume responsiveness in spontaneously breathing healthy adults.

Methods

We conducted a prospective study in healthy adult human volunteers. A PLR maneuver was performed and cardiac output (CO) was measured by transthoracic echocardiography. ET-CO2 was measured with non-invasive capnographs. Volume responsiveness was defined as an increase in cardiac output (CO) >?12% at 90 s after PLR.

Results

Of the 50 volunteers, 32% were classified as volume responders. In this group, the left ventricle outflow tract velocity time integral (VTI_LVOT) increased from 17.9?±?3.0 to 20.4?±?3.4 (p?=?0.0004), CO increased from 4.4?±?1.5 to 5.5?±?1.6 (p?=?0.0), and ET-CO₂ rose from 32 ±?4.84 to 33 ±?5.07 (p?=?0.135). Within the entire population, PLR-induced percentage ?CO was not correlated with percentage ?ET-CO₂ (R²?=?0.13; p?=?0.36). The area under the receiver operating curve for the ability of ET-CO₂ to discriminate responders from non-responders was of 0.67?±?0.09 (95% CI 0.498-0.853). A ?ET-CO₂???2 mmHg had a sensitivity of 50%, specificity of 97.06%, positive likelihood ratio of 17.00, negative likelihood ratio of 0.51, positive predictive value of 88.9%, and negative predictive value of 80.5% for the prediction of fluid responsiveness.

Conclusions

?ET-CO₂ after a PLR has limited utility to discriminate responders from non-responders among healthy spontaneously breathing adults.

SUBMITTER: Arango-Granados MC 

PROVIDER: S-EPMC6066588 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature