Low End-Tidal Carbon Dioxide at the Onset of Emergent Trauma Surgery Is Associated With Nonsurvival: A Case Series.

BACKGROUND

End-tidal carbon dioxide (EtCO2) is a valuable marker of the return of adequate circulation after cardiac arrest due to medical causes. Previously, the prognostic value of capnography in trauma has been studied among limited populations in prehospital and emergency department settings. We aimed to investigate the relationship between early intraoperative EtCO2 and nonsurvival of patients undergoing emergency surgery at a level 1 academic trauma center as a case series. If there is a threshold below which survival was extremely unlikely, it might be useful in guiding decision-making in the early termination of futile resuscitative efforts.

METHODS

After institutional review board approval, a data set was created to investigate the relationship between EtCO2 values at the onset of emergent trauma surgery and nonsurvival. Patients who were admitted and transferred to the operating room (OR) directly from a resuscitation bay were identified using the Ryder Center trauma registry (October 1, 2013, to June 30, 2016). Electronic records from the hospital's anesthesia information management system were queried to identify the matching anesthesia records. The maximum EtCO2 values within 5 and 10 minutes of the onset of mechanical ventilation in the OR were determined for patients undergoing general anesthesia with mechanical ventilation. Patients were divided into 2 groups: those who were discharged from the hospital alive (survivors) and those who died in the hospital before discharge (nonsurvivors). The threshold EtCO2 giving a positive predictive value of 100% for in-hospital mortality was determined from a graphical analysis of the data. Association of determined threshold and mortality was analyzed using the 2-tailed Fisher exact test.

RESULTS

There were 1135 patients who met the inclusion criteria. Within the first 5 minutes of the onset of mechanical ventilation in the OR, if the maximum EtCO2 value was ≤20 mm Hg, hospital mortality was 100% (21/21, 95% binomial confidence interval, 83.2%-100%).

CONCLUSIONS

A maximum EtCO2 ≤20 mm Hg within 5 minutes of the onset of mechanical ventilation in the OR may be useful in decision-making related to the termination of resuscitative efforts during emergent trauma surgery. However, a large-scale study is needed to establish the statistical reliability of this finding before potential adoption.