To determine how much information concerning resuscitation and outcome is provided by the end-tidal CO2 and derived variables obtained during surgery.Design
Retrospective chart review.Setting
Emergency hospital operating room.Patients
One hundred critically ill or injured patients requiring major surgery and having a mortality rate of 41%.Interventions
Standard intraoperative monitoring, including continuous capnography, plus arterial blood gas analyses every 1 to 1.5 hrs during surgery.Measurements and Main Results
There was only a fair correlation between the PaCO2 and end-tidal CO2 (r2 equals .14). The mortality rates in these patients were highest in those patients who had the lowest end-tidal CO2 values, the highest arterial to end-tidal CO2 differences, and the highest estimated alveolar deadspace fraction. A persistent end-tidal CO2 of less than equals 28 torr (less than equals 3.8 kPa) was associated with a mortality rate of 55% (vs. 17% in those patients with a higher end-tidal CO2). The mortality rate was also increased in patients with a persistent arterial to end-tidal CO2 difference of more than equals 8 torr (more than equals 1.1 kPa) (58% vs. 23%).Conclusions
End-tidal CO2 and derived values should be monitored closely in critically ill or injured patients. Efforts should be made--by increasing cardiac output and core temperature and by adjusting ventilation as needed--to maintain the end-tidal CO2 at more than equals 29 torr (more than equals 3.9 kPa) and the arterial to end-tidal CO2 difference at less than equals 7 torr (less than equals 1.0 kPa).