Inadequacy of visual alarms in helicopter air medical transport

Air medical programs use medical equipment primarily designed for hospital and/or ground transport settings. Many of these medical devices are equipped with auditory alarms of malfunction or deteriorating clinical status. The high ambient noise requires visual scanning of medical devices to detect alarm conditions in the helicopter cabin.

To evaluate the adequacy of visual scanning for alarm conditions in the helicopter air medical environment.

The helicopter transport program used in this study is staffed with two medical crewmembers. Flight nurse response time (RT) to a visual alarm was assessed during 25 air medical patient flights. RT was measured using a battery powered dual timer device with a red LED visual alarm placed in a fixed position among the medical instruments. The device was activated at a random time point unknown to the medical crew during each patient flight. RT was defined as the elapsed time from activation of the alarm until it was physically switched off by the flight nurse.

RT was surprisingly lengthy for the study population with a mean RT of 81.2 +/- 78.4 s (95% CI 48.8-113.5 s). The variability of RT was also surprising ranging from 3 s to > 5 min.

RT to visual alarms in the air medical environment is lengthy and quite variable. Recognition of malfunction of medical equipment or early signs of clinical instability prior to clinical deterioration cannot be assured by visual scanning for alarm conditions. Alternative alarming systems should be considered and investigated for air medical transport.