Representing patient vital signs with overlapping or serial earcon components

There is interest in how clinicians can achieve good awareness of their patients' wellbeing in a way that is not provided by conventional alarms. Earcons (short abstract sound motifs) provide an alternative. In three experiments we explored how effectively normal and abnormal levels of a patient's heart rate (HR), arterial oxygen saturation (SpO2) and blood pressure (BP) could be conveyed using two different earcon designs: overlapping (individual earcons for each vital sign played at the same time) or serial (individual earcons played one after the other). HR was mapped to the tremolo (sound vibration) rate in short bursts of white noise, SpO2 was mapped to the relative pitch of a tone, and BP was mapped to the range of an upward or downward sweep of pitch (chirp) of a tone. Experiment 1 compared how well non-clinician participants could identify HR and SpO2 using overlapping and serial mappings and found no difference in accuracy either for mapping or across vital signs. Experiment 2 added the BP vital sign, and compared overlapping and serial mappings. Identification accuracy was better with the serial mapping than with the overlapping mapping, and better for HR than for either SpO2 or BP. Experiment 3 replicated Experiment 2 but added conditions in which participants were cued to report a single vital sign in order to check whether memory limits or output interference were constraining the ability to report vital signs. When the cue appeared after the earcons were played, approximating a classic partial report paradigm, there was no improvement in identification accuracy, suggesting that earcon interpretability rather than memory load or output interference was constraining responses. However, when the cue appeared before the earcons were played, identification improved, suggesting that focused attention aided interpretation of the earcons. Although design modifications are needed, the results suggest that three vital signs may best be displayed in serial presentation for clinicians to maintain awareness of a patient's wellbeing in a convenient eyes-free manner.