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

Abstract

BackgroundEnd-tidal carbon dioxide (ETCO2) has previously shown promise as a predictor of shock severity and mortality in trauma. ETCO2 monitoring is non-invasive, real-time, and readily available in prehospital settings, but the temporal relationship of ETCO2 to systemic oxygen transport has not been thoroughly investigated in the context of hemorrhagic shock. MethodsA validated porcine model of hemorrhagic shock and resuscitation was used in male Yorkshire swine (N ​= ​7). Both ETCO2 and central venous oxygenation (SCVO2) were monitored and recorded continuously in addition to other traditional hemodynamic variables. ResultsLinear regression analysis showed that ETCO2 was associated with ScvO2 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 ETCO2. ConclusionsETCO2 and ScvO2 were closely associated during rapid hemorrhage and continued to be temporally associated throughout shock and resuscitation.