Apnea Testing for Brain Death/Death by Neurologic Criteria in Adults: A Prospective Multicenter Observational Study Assessing the Relationship Between Methodology, Safety, and Duration.

IMPORTANCE

Apnea testing is an integral component of brain death (BD) assessments. The optimal method of Apnea Testing is currently not known.

OBJECTIVES

To describe the current use of apnea test methods, and compare the effect of the chosen apnea test method (passive oxygenation, continuous positive airway pressure [CPAP], or exogenous Co2) on safety and duration of apnea test in adult BD/death by neurologic criteria (DNC) organ donors.

DESIGN

A prospective multicenter observational study.

SETTING

Seventy-four ICUs in Ontario, Canada, who participate in organ donation practices.

PATIENTS: All BD/DNC assessments in Ontario, Canada, from July 2023 to August 2024.

INTERVENTIONS: None.

MAIN OUTCOMES AND MEASURES: Outcomes included the rate of apnea test attempts, completions, and adverse events. We also measured the incidence of each method used and the duration of the apnea test.

RESULTS

During the 1-year study period, a total of 368 BD/DNC assessments were performed, of which 361 (98%) attempted an apnea test. Of the 361 apnea tests attempted, 236 (65%) used passive oxygenation (tracheal insufflation), 103 (29%) used CPAP-based methods, and 22 (6%) used exogenous Co2. Nine tests were not completed: seven were terminated due to adverse events (all with passive oxygenation; five hypoxemia, two hemodynamic instability) and two due to observed respiratory effort. All adverse events occurred with the passive oxygenation method (p = 0.20). No statistically significant differences were seen in apnea test duration between methods. The median test durations were 12 minutes (interquartile range [IQR], 10-17 min), 12 minutes (IQR, 8-15 min), and 15 minutes (IQR, 11-25 min) for passive oxygenation, positive pressure, and exogenous Co2, respectively.

CONCLUSIONS AND RELEVANCE: In this large multicenter study, passive oxygenation was associated with a nonsignificant increase in adverse events compared with CPAP-based and exogenous Co2 methods. Exogenous Co2 did not shorten apnea test time. These findings support further investigation of CPAP-based methods as an alternative approach to apnea testing and refinement of Co2 delivery parameters.