Early warning: End-tidal carbon dioxide is associated with central venous oxygenation under continuous cardiorespiratory monitoring in a porcine model of hemorrhagic shock and resuscitation.

Background: End-tidal carbon dioxide (ETCO) has previously shown promise as a predictor of shock severity and mortality in trauma. ETCO monitoring is non-invasive, real-time, and readily available in prehospital settings, but the temporal relationship of ETCO to systemic oxygen transport has not been thoroughly investigated in the context of hemorrhagic shock.

Methods: A validated porcine model of hemorrhagic shock and resuscitation was used in male Yorkshire swine (N ​= ​7). Both ETCO and central venous oxygenation (SO) were monitored and recorded continuously in addition to other traditional hemodynamic variables.

Results: Linear regression analysis showed that ETCO was associated with ScvO both throughout the experiment (β ​= ​1.783, 95% confidence interval (CI) [1.552-2.014], p ​< ​0.001) and during the period of most rapid hemorrhage (β ​= ​4.896, 95% CI [2.416-7.377], p ​< ​0.001) when there was a marked decrease in ETCO.

Conclusions: ETCO and ScvO were closely associated during rapid hemorrhage and continued to be temporally associated throughout shock and resuscitation.