INTRAOPERATIVE END-TIDAL CARBON-DIOXIDE LEVELS AND DERIVED CALCULATIONS CORRELATED WITH OUTCOME IN TRAUMA PATIENTS

Background: To determine the relationship between the prognosis of ser iously injured patients requiring emergency surgery and intraoperative end-tidal CO2 variables and ''excess PCO2.'' Method: Retrospective ch art review of 100 seriously injured patients admitted to Detroit Recei ving Hospital and requiring major surgery (mortality rate of 40%). Sta ndard intraoperative monitoring, including continuous capnography, plu s arterial blood analyses every 15 to 30 minutes during surgery. Resul ts: After resuscitation for 45 to 90 minutes, 11 patients had a systol ic blood pressure <100 mm Hg and, of these patients, 10 (91%) died. Of the remaining 89 patients, mortality rates were 53% (16/30), with an end-tidal CO2 of 22 mm Hg or less, versus 24% (14/59) with an end-tida l CO2 of 23 mm Hg or more (p=0.011). An arterial to end-tidal PCO2 dif ference of 13 mm Hg or more after resuscitation was associated with an increased mortality rate (50% (20/34 vs. 18% (20/55)) (p<0.005). The mortality rate was particularly high, with a final arterial to end-tid al PCO2 difference of 12 mm Hg or more (73% (30/41) versus 17% (10/59) (p<0.001)). A final PaCO2 excess (i.e., the amount by which the PaCO2 was higher than expected from the bicarbonate) >1.0 mm Hg was also as sociated with an increased mortality rate ((62% (33/53) vs. 15% (7/47) ) (p<0.001). Conclusion: Values derived from the end-tidal CO2 and the excess PCO2 should be monitored intraoperatively in critically injure d patients. Efforts should be made to improve cardiac output and adjus t ventilation to maintain and end-tidal PCO2 of 25 mm Hg or more, an a rterial to end-tidal CO2 difference of 12 mm Hg or less, and an excess PaCO2 of 1.0 mm Hg or less.