Abstract
Anesthetic management of patients who have suffered traumatic brain injuries can be challenging. We investigated the relationship between arterial to end-tidal carbon dioxide partial pressure gradients (Pa-etCO2) and 3 predictor variables: (1) injury severity score, (2) use of positive end-expiratory pressure, and (3) presence of rib fractures. Using a convenient sampling method, we sampled 56 patients who arrived to the operating room intubated after traumatic brain injuries between 2005 and 2011. Two groups were compared retrospectively: those with Pa-etCO2 greater than 10 mm Hg (case group) (n = 37) and those with Pa-etCO2 gradients of 10 mm Hg or less (control group) (n = 19). Descriptive and inferential statistics were employed to identify any differences between the groups. Stepwise regression was also performed. Cross tabulation analysis revealed that injury severity score of 30 or more was a predictor of Pa-etCO2 gradient. Stepwise regression analysis revealed the presence of rib fracture and body mass index to be significant predictors of Pa-etCO2 gradient (P < .011). This study identified coexisting conditions in which the patients' Pa-etCO2 gradients were large. Results showed that injury severity score of 30 or more, the presence of rib fractures, and higher body mass index were statistically significant predictors of Pa-etCO2 gradients greater than 10 mm Hg. These observations should be considered when evaluating PetCO2 in conjunction with arterial blood gas analysis to determine optimal ventilation status of these patients.