Comparison of Auditory Icon Alarms and Spearcon Sequences for Patient Monitoring

Auditory alarms in hospitals are intended to alert clinicians to physiological deterioration in a patient, and prompt them to intervene. The currently-recommended alarms are difficult to learn and remember (Wee & Sanderson, 2008), which could lead to ineffective patient monitoring. It is important to develop alternatives to the current alarms, especially to support the monitoring of multiple patients. Two possible alternatives are (1) auditory icon alarms (AIA) where sounds have a semantic relationship to the alarm source (Edworthy et al., 2018), or (2) spearcon sequences (SS), which are sequences of time compressed speech phrases presenting status information for multiple patients (Li, Tse, Brecknell, & Sanderson, 2019). Both alternatives have higher learnability and recognizability than the currently recommended alarms. In two experiments we compare the AIA and SS displays to test how well they support patient monitoring, focusing on prospective memory (PM) – the ability to remember to perform previously formed plans at an appropriate moment in the future (McDaniel & Einstein, 2007) – and situation awareness (SA) (Endsley, 1995). The AIA sounds are stylized snippets of everyday sounds to represent vital signs, such as a rattling pill sound to indicate drug administration. AIA maintain the same design philiosophy as the currently-recommended alarms by sounding only when a patient’s vital sign breaches a predetermined threshold. The SS used in both experiments use time compressed speech to signal different vital signs, the level of criticality the vital sign has reached, and in what direction, such as “heart rate very high”. Although alarms and AIA do not specify which patient they are referring to, SS can represent multiple patients by playing in a sequence. Finally, SS play a sound to indicate when a patient is in a normal state, rather than listeners having to rely on silence (which can be unreliable) as they do with the current alarms. In Experiment 1, the PM of non-clinicians was tested with AIA or SS sounds, while they did an ongoing arithmetic task. To ensure that PM performance was influenced by the sound properties, and not just by differences in the information provided by the auditory displays, we scored PM accuracy for (1) PM commands favoring the auditory icons (FavAIA), (2) PM commands favoring both displays equally (FavBoth), and (3) PM commands favoring the spearcon sequences (FavSS). Kruskal-Wallis tests found no significant differences across auditory displays in PM accuracy for FavAI commands and FavBoth commands, although there was a trend favoring SS for FavBoth. For FavSS commands, the mean rank for SS was significantly higher than for AIA, H(1) = 13.625, p < . 001. In Experiment 2, the SA of non-clinicians was tested with AIA or SS sounds while they did an ongoing tracking task. SS present information for multiple patients in sequences, but AIA does not. To overcome this disparity, sounds were played either from diffent directions associated with different patients (spatialized), or from just one direction (non-spatialized). Three categories of SA were probed: (1) Detailed Patient Status (DPS), which covers details only provided by SS, (2) Associate Patient and Alarm Category (APA) which involves associating specific alarms with specific patients and is impossible when AIA is not spatialised, and (3) Recognising Alarm State (RAS) which involves specificying vital signs and levels, and is possible in all conditions. For DPS questions, participants hearing SS had significantly higher SA than those hearing AIA, in both spatialized, H(1) = 25.48, p <. 001, and non-spatialized conditions, H(1) = 27.22, p <. 001. When sound was spatialized for APA questions there was no significant difference in SA accuracy between display conditions, H(1) = 5.56, p = . 018, although there was a trend towards higher SA accuracy in those hearing AIA. When sound was not spatialized for APA questions, participants hearing SS had significantly higher SA accuracy than those hearing AIA, H(1) = 16.06, p <. 001. For RAS questions, there was no significant difference in SA accuracy for participants hearing AIA and those hearing SS, in either spatialized or non-spatialized conditions (p values > .5). These two experiments were the first steps towards comparing how AIA and SS are monitored in a simulated clinical environment, and understanding how effectively they each support patient monitoring. Although future research with clinicians is needed, the studies advance our knowledge of auditory displays, and they highlight potential advantages of SS for supporting PM and SA. If SS continue to be more effective, they could replace the currently-recommended alarms, which may have benefits for patient care.