End-tidal carbon dioxide underestimates plasma carbon dioxide during emergent trauma laparotomy leading to hypoventilation and misguided resuscitation: A Western Trauma Association Multicenter Study

摘要

BACKGROUND End-tidal carbon dioxide (ETCO2) is routinely used during elective surgery to monitor ventilation. The role of ETCO2 monitoring in emergent trauma operations is poorly understood. We hypothesized that ETCO2 values underestimate plasma carbon dioxide (pCO(2)) values during resuscitation for hemorrhagic shock. METHODS Multicenter trial was performed analyzing the correlation between ETCO2 and pCO(2) levels. RESULTS Two hundred fifty-six patients resulted in 587 matched pairs of ETCO2 and pCO(2). Correlation between these two values was very poor with an R-2 of 0.04. 40.2% of patients presented to the operating room acidotic and hypercarbic with a pH less than 7.30 and a pCO(2) greater than 45 mm Hg. Correlation was worse in patients that were either acidotic or hypercarbic. Forty-five percent of patients have a difference greater than 10 mm Hg between ETCO2 and pCO(2). A pH less than 7.30 was predictive of an ETCO2 to pCO(2) difference greater than 10 mm Hg. A difference greater than 10 mm Hg was predictive of mortality independent of confounders. CONCLUSION Nearly one half (45%) of patients were found to have an ETCO2 level greater than 10 mm Hg discordant from their PCO2 level. Reliance on the discordant values may have contributed to the 40% of patients in the operating room that were both acidotic and hypercarbic. Early blood gas analysis is warranted, and a lower early goal of ETCO2 should be considered.