Risk of complications using a sedation protocol for aeromedical retrieval of acutely unwell mental health patients: a retrospective cohort study in Outback Australia.

Background: Aeromedical transfer of acutely unwell mental health (AMH) patients presents potential risks to patient, staff and aircraft. Pharmacological options to reduce risk can impair consciousness, risking airway compromise and management challenges in-flight. Pre-emptive intubation carries associated patient risks and requires a receiving intensive care unit bed. This study aimed to assess the risk of complications using a protocolised approach to sedation of AMH patients undergoing retrieval in New South Wales, Australia.

Methods: This retrospective cohort study included all aeromedical transfers of AMH patients performed by the Royal Flying Doctor Service South Eastern Section (RFDSSE) between 1 January 2011 and 31 December 2022. AMH patients whose treatment during transfer aligned with the RFDSSE Mental Health (MH) transfer protocol ('On Protocol', OnP) were compared against the 'Off Protocol' (OffP) group. Patient characteristics (MH risk assessment score), transfer characteristics (duration), medications administered and complications (any, severe) experienced were compared using univariate analyses.

Results: Treatment aligned with MH transfer protocol (ie, OnP) in 45.9% (n=39) of 85 cases. Complications were more common in the OffP group (54.3% vs 25.6%, a difference of 28.7% (95% CI 7.8% to 46.2%)). Similarly severe complications occurred more frequently in the OffP group (37.0% vs 5.1%, a difference of 31.8% (95% CI 14.7% to 46.7%)). Intubated patients (n=9, all OffP) had the highest rate of severe complications at 66.7%, followed by patients who received midazolam (n=33, all OffP), with a severe complication rate of 30.3%.

Conclusion: A protocolised approach to sedation of AMH patients undergoing aeromedical retrieval, including the use of ketamine sedation, was associated with fewer complications overall, fewer severe complications and no episodes of treatment failure or need for intubation. Our findings suggest that the use of midazolam and/or intubation in this cohort is associated with a higher risk of complications, and ketamine presents a safer alternative.