Buccal partial pressure of carbon dioxide outweighs traditional vital signs in predicting the severity of hemorrhagic shock in a rat model

BackgroundHemorrhagic shock (HS) is a leading cause of death in both military and civilian settings. Researchers have investigated different parameters as predictors of HS, but reached inconsistent conclusions. We hypothesized that buccal partial pressure of carbon dioxide (PCO2) was a better predictor of HS than traditional vital signs.Materials and methodsTwenty-four anesthetized Wistar rats were randomly divided into four groups: one control group (no bleeding) and three surgical groups (25%, 35%, and 45% blood loss). Hemorrhage was induced by withdrawing blood from the left femoral artery over a period of 30 min. After that, resuscitation was performed on animals in surgical groups using the Ringer lactate solution. Buccal PCO2 was continuously measured by a newly designed sensor holder during the experiments. Traditional vital signs, cardiac output, base excess, and microvascular perfusion (MPF) were also measured or calculated.ResultsBuccal PCO2 differed significantly among four groups beginning at 20 min, approximately 10 min earlier than the shock index and more earlier than the heart rate, systolic blood pressure, and mean arterial pressure. Buccal PCO2 correlated well with cardiac index and the changes in MPF. The correlation coefficients with cardiac index, chest MPF, and upper-limb MPF for buccal PCO2 were 0.781, −0.879, and −0.946, respectively. Besides, buccal PCO2 showed a good value for predicting mortality. Furthermore, an approximate critical threshold of buccal PCO2 was also identified for predicting the severity of HS.ConclusionsBuccal PCO2 was a noninvasive, sensitive indicator of HS than traditional vital signs and may help on-scene rescuers administer early treatment of injured patients.