Abnormal end-tidal carbon dioxide levels on emergency department arrival in adult and pediatric intubated patients.

BACKGROUND: The utility of prehospital intubation is controversial, as uncontrolled studies in trauma patients suggest adverse outcomes with prehospital intubation, perhaps secondary to inappropriate ventilation once intubation is accomplished.

OBJECTIVES: The objectives were 1) to establish, immediately upon arrival to the emergency department (ED), the prevalence of abnormal end-tidal carbon dioxide (ETCO(2)) levels in patients with prehospital intubation and 2) to describe the relationship between abnormal ETCO(2) levels on ED arrival and mortality.

METHODS: This was a prospective, observational cohort study of patients with prehospital intubation. Patients were excluded if they underwent prehospital cardiopulmonary resuscitation (CPR). On ED arrival, the initial ETCO(2) measurement from the patient's endotracheal tube was immediately obtained prior to purposeful intervention in the patient's ventilation by using an Oridion Surestream Sure VentLine H Set with a Welch Allyn Propaq CS monitor. For each patient, the treating physician documented the ETCO(2) measurement, patient demographics, and details of the transport. The primary outcome was an abnormal ETCO(2) value (<30 mmHg or >45 mmHg). The secondary outcome was mortality.

RESULTS: One hundred eligible patients were enrolled, with a median age of 30 years (interquartile range [IQR] 15, 48 years). Esophageal intubations were identified in four cases, and those cases were excluded from further analysis. Mechanisms included trauma, 74; medical, 12; and burn, 10. The median ETCO(2) value was 32 mmHg (IQR 27, 38 mmHg), range 18-80 mmHg. Forty-six of 96 (48%, 95% confidence interval [CI] 38%, 58%) patients had abnormal ETCO(2) values, including 37 (39%, 95% CI 29%, 49%) with low ETCO(2) levels and nine (9%, 95% CI 4%, 17%) with high ETCO(2) levels. Death was higher in those trauma patients with abnormal ETCO(2) levels (10/33, 30%, 95% CI 16%, 49%) than in those with normal ETCO(2) levels (2/41, 5%, 95% CI 0.6%, 17%), relative risk = 6.2 (95% CI 1.5, 26.4), p = 0.004.

CONCLUSION: Nearly half of all patients transported by prehospital providers had abnormal ETCO(2) measurements on initial ED presentation, suggesting an area for potential improvement. Trauma patients with abnormal initial ETCO(2) levels were more likely to die.