Evaluation of an enhanced pulse oximeter auditory display: a simulaion study

Background: We compared anaesthetists' ability to identify haemoglobin oxygen saturation (SpO₂) levels using two auditory displays: one based on a standard pulse oximeter display (varying pitch plus alarm) and the other enhanced with additional sound properties (varying pitch plus tremolo and acoustic brightness) to differentiate SpO₂ ranges. Methods: In a counter-balanced crossover study in a simulator, 20 experienced anaesthetists supervised a junior colleague (an actor) managing two airway surgery scenarios: once while using the enhanced auditory display and once while using a standard auditory display. Participants were distracted with other tasks such as paperwork and workplace interruptions, but were required to identify when SpO₂ transitioned between pre-set ranges (target, low, critical) and when other vital signs transitioned out of a target range. They also identified the range once a transition had occurred. Visual displays were available for all monitored vital signs, but the numerical value for SpO₂ was excluded. Results: Participants were more accurate and faster at detecting transitions to and from the target SpO₂ range when using the enhanced display (100.0%, 3.3 s) than when using the standard display plus alarm (73.2%, 27.4 s) (P<0.001 and P=0.004, respectively). They were also more accurate at identifying the SpO₂ range once a transition had occurred when using the enhanced display (100.0%) than when using the standard display plus alarm (57.1%; P<0.001). Conclusions: The enhanced auditory display helps anaesthetists judge SpO₂ levels more effectively than current auditory displays and may facilitate ‘eyes-free’ monitoring.