Evaluating enhanced pulse oximetry auditory displays for neonatal oxygen targeting: A randomized laboratory trial with clinicians and non-clinicians.

Standard pulse oximeter auditory tones do not clearly indicate departures from the target range of oxygen saturation (SpO2) of 90%-95% in preterm neonates. We tested whether acoustically enhanced tones would improve participants' ability to identify SpO2 range. Twenty-one clinicians and 23 non-clinicians used (1) standard pulse oximetry variable-pitch tones plus alarms; (2) beacon-enhanced tones without alarms in which reference tones were inserted before standard pulse tones when SpO2 was outside target range; and (3) tremolo-enhanced tones without alarms in which pulse tones were modified with tremolo when SpO2 was outside target range. For clinicians, range identification accuracies (mean (SD)) in the standard, beacon, and tremolo conditions were 52% (16%), 73% (14%) and 76% (13%) respectively, and for non-clinicians 49% (16%), 76% (13%) and 72% (14%) respectively, with enhanced conditions always significantly more accurate than standard. Acoustic enhancements to pulse oximetry clearly indicate departures from preterm neonates' target SpO2 range.

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.

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 (SpO2). Current auditory displays are not always effective at providing SpO2 information. In this laboratory study, clinician and nonclinician participants identified SpO2 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 SpO2 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 SpO2 target range and (2) identify SpO2 range (target, low, or critical). Secondary outcomes included participants' latency to detect target transitions, accuracy to identify absolute SpO2 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 SpO2 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, SpO2 range identification accuracy, or absolute SpO2 value identification. CONCLUSIONS: The enhanced auditory display supports more accurate detection of target transitions and identification of SpO2 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 SpO2 outcomes than nonclinician participants.

Supporting multiple patient monitoring with head-worn displays and spearcons.

In hospitals, clinicians often need to monitor several patients while performing other tasks. However, visual displays that show patients' vital signs are in fixed locations and auditory alarms intended to alert clinicians may be missed. Information such as spearcons (time-compressed speech earcons) that 'travels' with the clinician and is delivered by earpiece and/or head-worn displays (HWDs), might overcome these problems. In this study, non-clinicians monitored five simulated patients in three 10-min scenarios while performing a demanding tracking task. Monitoring accuracy was better for participants using spearcons and a HWD (88.7%) or a HWD alone (86.2%) than for participants using spearcons alone (74.1%). Participants using the spearcons and HWD (37.7%) performed the tracking task no differently from participants using spearcons alone (37.1%) but participants using the HWD alone performed worse overall (33.1%). The combination of both displays may be a suitable solution for monitoring multiple patients.

Monitoring vital signs with time-compressed speech.

Spearcons-time-compressed speech phrases-may be an effective way of communicating vital signs to clinicians without disturbing patients and their families. Four experiments tested the effectiveness of spearcons for conveying oxygen saturation (SpO2) and heart rate (HR) of one or more patients. Experiment 1 demonstrated that spearcons were more effective than earcons (abstract auditory motifs) at conveying clinical ranges. Experiment 2 demonstrated that casual listeners could not learn to decipher the spearcons whereas listeners told the exact vocabulary could. Experiment 3 demonstrated that participants could interpret sequences of sounds representing multiple patients better with spearcons than with pitch-based earcons, especially when tones replaced the spearcons for normal patients. Experiment 4 compared multiple-patient monitoring of two vital signs with either spearcons, a visual display showing SpO2 and HR in the same temporal sequence as the spearcons, or a visual display showing multiple patient levels simultaneously. All displays conveyed which patients were abnormal with high accuracy. Visual displays better conveyed the vital sign levels for each patient, but cannot be used eyes-free. All displays showed accuracy decrements with working memory load. Spearcons may be viable for single and multiple patient monitoring. Further research should test spearcons with more vital signs, during multitasking, and longitudinally. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

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.

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 (SpO2) 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' SpO2 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.

A Novel Auditory Display for Neonatal Resuscitation: Laboratory Studies Simulating Pulse Oximetry in the First 10 Minutes After Birth.

OBJECTIVE: We tested whether enhanced sonifications would improve participants' ability to judge the oxygen saturation levels (SpO2) of simulated neonates in the first 10 min after birth. BACKGROUND: During the resuscitation of a newborn infant, clinicians must keep the neonate's SpO2 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 SpO2 levels using the current sonification. METHOD: In two experiments, nonclinicians' ability to detect SpO2 range and direction-while performing continuous arithmetic problems-was tested with enhanced versus conventional sonifications. In Experiment 1, tremolo signaled when SpO2 had deviated below or above the target range. In Experiment 2, tremolo plus brightness signaled when SpO2 was above target range, and tremolo alone when SpO2 was below target range. RESULTS: 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 <.001). In both experiments, there was no difference across conditions in arithmetic task accuracy ( p >.05). CONCLUSION: Using the enhanced sonifications, participants identified SpO2 range more accurately despite a continuous distractor task. APPLICATION: An enhanced pulse oximetry sonification could help clinicians multitask more effectively during neonatal resuscitations.

Spearcons for Patient Monitoring: Laboratory Investigation Comparing Earcons and Spearcons.

Objective We compared the effectiveness of single-tone earcons versus spearcons in conveying information about two commonly monitored vital signs: oxygen saturation and heart rate. Background The uninformative nature of many medical alarms-and clinicians' lack of response to alarms-is a widespread problem that can compromise patient safety. Auditory displays, such as earcons and spearcons (speech-based earcons), may help clinicians maintain awareness of patients' well-being and reduce their reliance on alarms. Earcons are short abstract sounds whose properties represent different types and levels of information, whereas spearcons are time-compressed spoken phrases that directly state their meaning. Listeners might identify patient vital signs more accurately with spearcons than with earcons. Method In Experiment 1 we compared how accurately 40 nonclinician participants using either (a) single-tone earcons differentiated by timbre and tremolo or (b) Cantonese spearcons recorded using a female Cantonese voice could identify both oxygen saturation and heart rate levels. In Experiment 2 we tested the identification performance of six further nonclinician participants with spearcons recorded using a male Cantonese voice. Results In Experiment 1, participants using spearcons identified both vital signs together more accurately than did participants using earcons. Participants using Cantonese spearcons also learned faster, completed trials faster, identified individual vital signs more accurately, and felt greater ease and more confident when identifying oxygen saturation levels. Experiment 2 verified the previous findings with male-voice Cantonese spearcons. Conclusion Participants identified vital signs more accurately using spearcons than with the single-tone earcons. Application Spearcons may be useful for patient monitoring in situations in which intermittently presented information is desirable.

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.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.