What happens to SpO2 during air medical crew intubations?

Studies finding adverse outcomes associated with emergency medical services intubation (ETI) have prompted recommendations for prehospital services to improve tracking of oxygenation during airway management. Our goals were to 1) implement a documentation requirement for helicopter EMS (HEMS) crews, entailing tracking and notation of the lowest SpO2 value (peri-ETI SpO2 nadir) occurring during HEMS crew ETI, and 2) assess the findings associated with the peri-ETI SpO2 documentation parameter.

This was a prospective study conducted at an urban HEMS program with flight nurse/flight paramedic staffing and protocol-driven care. There were 200 consecutive cases undergoing HEMS ETI between April 2004 and July 2005. Univariate logistic regression with odds ratio (OR) was used to assess for association between ETI-related hypoxemia (decrease in SpO2 value to < 90% during ETI) and patient/intubator characteristics.

HEMS crew ETI was successful in 189 (95.4%) of the 200 patients. The lowest peri-ETI SpO2 value was specifically documented in 170 patients (85%) in the study group. In univariate analysis, successful crew ETI was correlated with avoidance of crew-recorded SpO2 value decreasing to < 90% (OR, 0.23; 95% confidence interval, 0.07-0.83). Similarly, requirement for multiple attempts at ETI was correlated with higher likelihood that crews recorded peri-ETI SpO2 value decreasing to < 90% (OR, 7.8; 95% confidence interval, 3.2-18.8). However, in nearly two thirds of cases in which multiple attempts were executed, the peri-ETI SpO2 value remained > 90%. Of the seven patients in whom rescue laryngeal mask airways were placed, the peri-ETI SpO2 value remained > 90% in three (42.9%).

Documentation of crew-recorded peri-ETI SpO2 nadir is a useful and practical prehospital data point.