Using a sequence of earcons to monitor multiple simulated patients

Objective: The aim of this study was to determine whether a sequence of earcons can effectively convey the status of multiple processes, such as the status of multiple patients in a clinical setting. Background: Clinicians often monitor multiple patients. An auditory display that intermittently conveys the status of multiple patients may help. Method: Nonclinician participants listened to sequences of 500-ms earcons that each represented the heart rate (HR) and oxygen saturation (SpO2) levels of a different simulated patient. In each sequence, one, two, or three patients had an abnormal level of HR and/or SpO2. In Experiment 1, participants reported which of nine patients in a sequence were abnormal. In Experiment 2, participants identified the vital signs of one, two, or three abnormal patients in sequences of one, five, or nine patients, where the interstimulus interval (ISI) between earcons was 150 ms. Experiment 3 used the five-sequence condition of Experiment 2, but the ISI was either 150 ms or 800 ms. Results: Participants reported which patient(s) were abnormal with median 95% accuracy. Identification accuracy for vital signs decreased as the number of abnormal patients increased from one to three, p < .001, but accuracy was unaffected by number of patients in a sequence. Overall, identification accuracy was significantly higher with an ISI of 800 ms (89%) compared with an ISI of 150 ms (83%), p < .001. Conclusion: A multiple-patient display can be created by cycling through earcons that represent individual patients. Application: The principles underlying the multiple-patient display can be extended to other vital signs, designs, and domains

The sounds of desaturation: A survey of commercial pulse oximeter sonifications

The pulse oximeter has been a standard of care medical monitor for >25 years. Most manufacturers include a variable-pitch pulse tone in their pulse oximeters. Research has shown that the acoustic properties of variable-pitch tones are not standardized. In this study, we surveyed the properties of pulse tones from 21 pulse oximeters, consisting of 1 to 4 instruments of 11 different models and 8 brands. Our goals were to fully document the sounds over saturation values 0% to 100%, test whether tones become quieter at low saturation values, and create a public repository of pulse oximeter recordings for future use.A convenience sample of commercial pulse oximeters in use at one hospital was studied. Audiovisual recordings of each pulse oximeter's display and sounds were taken while it monitored a simulator starting at a saturation of 100% and slowly decreasing in 1% steps until the saturation reached 0%. Recorded pulse tones were analyzed for spectral frequency and total power. Audio files for each pulse oximeter containing 100 pulse tones, one at every saturation value, were created for inclusion in the repository.Recordings containing 509 to 1053 pulse tones were made from the 21 pulse oximeters. Fundamental frequencies at 100% saturation ranged from 479 to 921 Hz, and fundamental frequencies at 1% saturation ranged from 38 to 404 Hz. The pulse tones from all but one model pulse oximeter contained harmonics. Pulse tone step sizes were linear in 6 models and logarithmic in 6 models. Only 6 pulse oximeter models decreased the pulse tone pitch at every decrease in saturation; all others decreased the pitch at only select saturation thresholds. Five pulse oximeter models stopped decreasing pitch altogether once the saturation reached a certain lower threshold. Pulse tone power (perceived as loudness) changed with saturation level for all pulse oximeters, increasing above baseline as saturation decreased from 100% and decreasing to levels below baseline at low saturation values.Current pulse oximeters use different techniques to address the competing goals of (1) using pitch steps that are large enough to be readily perceived, and (2) conveying saturation values from 0 to 100 within a limited range of sound frequencies. From a clinical perspective, 2 techniques for increasing perceivability (increasing the frequency range and using ratio step sizes) have no drawback, but 2 techniques (not changing pitch at every saturation change and using a lower saturation cutoff) do have potential clinical drawbacks. On the basis of our findings, we have made suggestions for clinicians and manufacturers

A novel auditory display for neonatal resuscitation: laboratory studies simulating pulse oximetry in the first 10 minutes after birth

We tested whether enhanced sonifications would improve participants' ability to judge the oxygen saturation levels (SpO) of simulated neonates in the first 10 min after birth.During the resuscitation of a newborn infant, clinicians must keep the neonate's SpO levels within the target range, however the boundaries for the target range change each minute during the first 10 min after birth. Resuscitation places significant demand on the clinician's visual attention, and the pulse oximeter's sonification could provide eyes-free monitoring. However, clinicians have difficulty judging SpO levels using the current sonification.In two experiments, nonclinicians' ability to detect SpO range and direction-while performing continuous arithmetic problems-was tested with enhanced versus conventional sonifications. In Experiment 1, tremolo signaled when SpO had deviated below or above the target range. In Experiment 2, tremolo plus brightness signaled when SpO was above target range, and tremolo alone when SpO was below target range.The tremolo sonification improved range identification accuracy over the conventional display (81% vs. 63%, p < .001). The tremolo plus brightness sonification further improved range identification accuracy over the conventional display (92% vs. 62%, p .05).Using the enhanced sonifications, participants identified SpO range more accurately despite a continuous distractor task.An enhanced pulse oximetry sonification could help clinicians multitask more effectively during neonatal resuscitations

The impact of concurrent linguistic tasks on participants’ identification of spearcons

Spearcons (time-compressed speech) may be a viable display for patient monitoring, but the impact of concurrent linguistic tasks on spearcons has not been examined. We tested whether different concurrent linguistic tasks worsen participants’ identification of spearcons. Experiment 1 tested participants’ identification of spearcons representing 2 vital signs of 5 patients while participants did either no concurrent task, reading, or saying linguistic tasks. Experiment 2 tested identification of 48 single patient-monitoring spearcons while participants did no concurrent task, reading, listening, and saying linguistic tasks. In Experiment 1 the saying task worsened participants’ identification of spearcons compared with the other tasks. In Experiment 2, the saying and listening tasks each reduced participants’ accuracy at identifying spearcons, but the reading task did not. Listening had no more effect than the saying task did. Concurrent listening and saying tasks worsen participants’ identification of spearcons, probably due to auditory modality interference in working memory

The impact of concurrent linguistic tasks on participants’ identification of spearcons

Spearcons (time-compressed speech) may be a viable auditory display for patient monitoring; however, the impact of concurrent linguistic tasks remains unexamined. We tested whether different concurrent linguistic tasks worsen participants' identification of spearcons. Experiment 1 tested non-clinician participants' identification of multiple-patient spearcons representing 2 vital signs of 5 patients while participants performed no concurrent task, reading, or saying linguistic tasks. Experiment 2 tested non-clinician participants' identification of 48 single-patient spearcons while they performed no concurrent task, reading, listening, and saying linguistic tasks. In Experiment 1 the saying task worsened participants' identification of spearcons compared with no concurrent task or reading. In Experiment 2, the saying and listening tasks reduced participants' accuracy at identifying spearcons, but the reading task did not. Listening affected identification accuracy no differently than the saying task did. Concurrent auditory linguistic tasks worsen participants’ identification of spearcons, probably due to auditory modality interference in verbal working memory

Spearcon sequences for monitoring multiple patients: laboratory investigation comparing two auditory display designs

Objective: The aim was to compare the effectiveness of two auditory displays, implemented with spearcons (time-compressed speech), for monitoring multiple patients. Background: Sequences of sounds can convey information about patients’ vital signs, such as oxygen saturation (SpO) and heart rate (HR). We tested whether participants could monitor five patients using spearcon-based sound sequences. Method: A 2 × 3 within-subjects design was used. The first factor was interface, with two levels: the ALL interface used spearcons to convey vital signs for all five patients, whereas the ABN (abnormal) interface represented patients who had normal vital signs with a low-pitched single-tone sound and patients who had at least one abnormal vital sign with spearcons. The second factor was the number of patients who had at least one abnormal vital sign: there were one, two, or three such patients in each monitoring sequence. Participants were 40 nonclinicians. Results: Participants identified abnormal patients’ SpO and HR levels and located abnormal patients in the sound sequence more accurately with the ABN interface than the ALL interface. Accuracy declined as the number of abnormal patients increased. Participants associated ABN with easier identification of vital signs, resulting in higher ratings of confidence and pleasantness compared with ALL. Conclusion: Sequences of spearcons may support effective eyes-free monitoring of multiple patients. Application: Sequences of spearcons may be useful in monitoring multiple patients and the underlying design principles may extend to monitoring in other domains such as industrial process control or control of multiple autonomous vehicles

Comparison of standard and enhanced pulse oximeter auditory displays of oxygen saturation: a laboratory study with clinician and nonclinician participants

BACKGROUND: When engaged in visually demanding tasks, anesthesiologists depend on the auditory display of the pulse oximeter (PO) to provide information about patients' oxygen saturation (Spo(2)). Current auditory displays are not always effective at providing Spo(2) information. In this laboratory study, clinician and nonclinician participants identified Spo(2) parameters using either a standard auditory display or an auditory display enhanced with additional acoustic properties while performing distractor tasks and in the presence of background noise. METHODS: In a counterbalanced crossover design, specialist or trainee anesthesiologists (n = 25) and nonclinician participants (n = 28) identified Spo(2) parameters using standard and enhanced PO auditory displays. Participants performed 2 distractor tasks: (1) arithmetic verification and (2) keyword detection. Simulated background operating room noise played throughout the experiment. Primary outcomes were accuracies to (1) detect transitions to and from an Spo(2) target range and (2) identify Spo(2) range (target, low, or critical). Secondary outcomes included participants' latency to detect target transitions, accuracy to identify absolute Spo(2) values, accuracy and latency of distractor tasks, and subjective judgments about tasks. RESULTS: Participants were more accurate at detecting target transitions using the enhanced display (87%) than the standard display (57%; odds ratio, 7.3 [95% confidence interval {CI}, 4.4-12.3]; P < .001). Participants were also more accurate at identifying Spo(2) range using the enhanced display (86%) than the standard display (76%; odds ratio, 2.7 [95% CI, 1.6-4.6]; P < .001). Secondary outcome analyses indicated that there were no differences in performance between clinicians and nonclinicians for target transition detection accuracy and latency, Spo(2) range identification accuracy, or absolute Spo(2) value identification. CONCLUSIONS: The enhanced auditory display supports more accurate detection of target transitions and identification of Spo(2) range for both clinicians and nonclinicians. Despite their previous experience using PO auditory displays, clinicians in this laboratory study were no more accurate in any Spo(2) outcomes than nonclinician participants

The impact of head-worn displays on strategic alarm management and situation awareness

Objective: To investigate whether head-worn displays (HWDs) help mobile participants make better alarm management decisions and achieve better situation awareness than alarms alone. Background: Patient alarms occur frequently in hospitals but often do not require clinical intervention. Clinicians may become desensitized to alarms and fail to respond to clinically relevant alarms. HWDs could make patient information continuously accessible, support situation awareness, and help clinicians prioritize alarms. Method: Experiment 1 (n = 76) tested whether nonclinicians monitoring simulated patients benefited from vital sign information continuously displayed on an HWD while they performed a secondary calculation task. Experiment 2 (n = 13) tested, across three separate experimental sessions, how effectively nursing trainees monitored simulated patients’ vital signs under three different display conditions while they assessed a simulated patient. Results: In Experiment 1, participants who had access to continuous patient information on an HWD responded to clinically important alarms 25.9% faster and were 6.7 times less likely to miss alarms compared to participants who only heard alarms. In Experiment 2, participants using an HWD answered situation awareness questions 18.9% more accurately overall than when they used alarms only. However, the effect was significant in only two of the three experimental sessions. Conclusion: HWDs may help users maintain continuous awareness of multiple remote processes without affecting their performance on ongoing tasks. Application: The outcomes may apply to contexts where access to continuous streams of information from remote locations is useful, such as patient monitoring or clinical supervision