Improving detectability of auditory interfaces for medical alarms through temporal variation in amplitude envelope.

BACKGROUND: Auditory interfaces play a vital role in many applications, informing users about both urgent and routine information critical to safety. Unfortunately, problems related to high alarm rates, low reliability, and sound annoyance create barriers to optimising the quality of patient care in perioperative medicine and critical care. Here, we explore how to reduce annoyance and improve detection by manipulating a sound's temporal envelope or the way its energy changes over time. METHODS: In the first experiment, participants were asked to detect a series of percussive and flat tones presented at six signal-to-noise ratios while performing a concurrent speech comprehension task. In the second experiment, different participants were asked to evaluate the relative annoyance of these same sounds. RESULTS: Relative to industry-standard flat tones, percussive tones were significantly less annoying and more detectable. Although more detectable, percussive tones did not impair concurrent speech comprehension. CONCLUSIONS: Temporal variation in amplitude envelope represents a promising path towards improving auditory interfaces for patient monitoring. By using temporally variable sounds, auditory interfaces can be more effective in alerting users. This is important for safety-critical areas, such as medical alarms, where annoyance often limits efficacy. As this manipulation can preserve the pitch and rhythm of tone sequences, it is compatible with users' pre-existing knowledge of current alarms.

Auditory roughness: a delicate balance.

Auditory roughness in medical alarm sounds is an important design attribute, and has been shown to impact user performance and perception. While roughness can assist in decreased signal-to-noise ratios (perceived loudness) and communicate urgency, it might also impact patient recovery. Therefore, considerations of neuroscience correlates, music theory, and patient impact are critical aspects to investigate in order to optimise alarm design.

Multisensory alarm to benefit alarm identification and decrease workload: a feasibility study.

The poor design of conventional auditory medical alarms has contributed to alarm desensitization, and eventually, alarm fatigue in medical personnel. This study tested a novel multisensory alarm system which aims to help medical personnel better interpret and respond to alarm annunciation during periods of high cognitive load such as those found within intensive care units. We tested a multisensory alarm that combined auditory and vibrotactile cues to convey alarm type, alarm priority, and patient identity. Testing was done in three phases: control (conventional auditory), Half (limited multisensory alarm), and Full (complete multisensory alarm). Participants (N = 19, undergraduates) identified alarm type, priority, and patient identity (patient 1 or 2) using conventional and multisensory alarms, while simultaneously completing a cognitively demanding task. Performance was based on reaction time (RT) and identification accuracy of alarm type and priority. Participants also reported their perceived workload. RT was significantly faster for the Control phase (p < 0.05). Participant performance in identifying alarm type, priority, and patient did not differ significantly between the three phase conditions (p = 0.87, 0.37, and 0.14 respectively). The Half multisensory phase produced the lowest mental demand, temporal demand, and overall perceived workload score. These data suggest that implementation of a multisensory alarm with alarm and patient information may decrease perceived workload without significant changes in alarm identification performance. Additionally, a ceiling effect may exist for multisensory stimuli, with only part of an alarm benefitting from multisensory integration.

A Spatiotemporal and Multisensory Approach to Designing Wearable Clinical ICU Alarms.

In health care, auditory alarms are an important aspect of an informatics system that monitors patients and alerts clinicians attending to multiple concurrent tasks. However, the volume, design, and pervasiveness of existing Intensive Care Unit (ICU) alarms can make it difficult to quickly distinguish their meaning and importance. In this study, we evaluated the effectiveness of two design approaches not yet explored in a smartwatch-based alarm system designed for ICU use: (1) using audiovisual spatial colocalization and (2) adding haptic (i.e., touch) information. We compared the performance of 30 study participants using ICU smartwatch alarms containing auditory icons in two implementations of the audio modality: colocalized with the visual cue on the smartwatch's low-quality speaker versus delivered from a higher quality speaker located two feet away from participants (like a stationary alarm bay situated near patients in the ICU). Additionally, we compared participant performance using alarms with two sensory modalities (visual and audio) against alarms with three sensory modalities (adding haptic cues). Participants were 10.1% (0.24s) faster at responding to alarms when auditory information was delivered from the smartwatch instead of the higher quality external speaker. Meanwhile, adding haptic information to alarms improved response times to alarms by 12.2% (0.23s) and response times on their primary task by 10.3% (0.08s). Participants rated learnability and ease of use higher for alarms with haptic information. These small but statistically significant improvements demonstrate that audiovisual colocalization and multisensory alarm design can improve user response times.

Improved Patient Monitoring with a Novel Multisensory Smartwatch Application.

The design of medical alarms has been heavily criticized in the past decade. Auditory medical alarms have poor learnability, discernibility, and relevance, leading to poor patient outcomes, and alarm fatigue, and overall poor informatic system design. We developed a novel trimodal patient monitoring smartwatch application for patient monitoring. Participants completed two phases: (1) control and (2) our novel trimodal system while identifying alarms (heart rate, oxygenation, and blood pressure) and completing a cognitively demanding task. Alarms were auditory icons presented as either solo or co-alarms. Participant performance was assessed by accuracy and response time (RT) of alarm identification. Using the novel system, accuracy was significantly improved overall (p < 0.01) and in co-alarm situations (p < 0.01), but not for solo alarms (p = 0.484). RT was also significantly faster (p < 0.01) while using the novel system for all alarm types. Participants reported decreased mental workload using the novel system. This feasibility study shows that our novel alarm system performs better than current standards. Improvements in accuracy, RT and perceived mental workload indicate the potential of this system to have a positive impact on medical informatic systems and clinical monitoring, for both the patient and the clinician.

The Influence of Audible Alarm Loudness and Type on Clinical Multitasking.

In high-consequence industries such as health care, auditory alarms are an important aspect of an informatics system that monitors patients and alerts providers attending to multiple concurrent tasks. Alarms levels are unnecessarily high and alarm signals are uninformative. In a laboratory-based task setting, we studied 25 anesthesiology residents' responses to auditory alarms in a multitasking paradigm comprised of three tasks: patient monitoring, speech perception/intelligibility, and visual vigilance. These tasks were in the presence of background noise plus/minus music, which served as an attention-diverting stimulus. Alarms signified clinical decompensation and were either conventional alarms or a novel informative auditory icon alarm. Both alarms were presented at four different levels. Task performance (accuracy and response times) were analyzed using logistic and linear mixed-effects regression. Salient findings were 1), the icon alarm had similar performance to the conventional alarm at a +2 dB signal-to-noise-ratio (SNR) (accuracy: OR 1.21 (95% CI 0.88, 1.67), response time: 0.04 s at 2 dB (95% CI: -0.16, 0.24), which is a much lower level than current clinical environments; 2) the icon alarm was associated with 27% greater odds (95% CI: 18%, 37%) of correctly addressing the vigilance task, regardless of alarm SNR, suggesting crossmodal/multisensory multitasking benefits; and 3) compared to the conventional alarm, the icon alarm was associated with an absolute improvement in speech perception of 4% in the presence of an attention-diverting auditory stimulus (p = 0.031). These findings suggest that auditory icons can provide multitasking benefits in cognitively demanding clinical environments.

Delirium Variability is Influenced by the Sound Environment (DEVISE Study): How Changes in the Intensive Care Unit soundscape affect delirium incidence.

Quantitative data on the sensory environment of intensive care unit (ICU) patients and its potential link to increased risk of delirium is limited. We examined whether higher average sound and light levels in ICU environments are associated with delirium incidence. Over 111 million sound and light measurements from 143 patient stays in the surgical and trauma ICUs were collected using Quietyme® (Neshkoro, Wisconsin) sensors from May to July 2018 and analyzed. Sensory data were grouped into time of day, then normalized against their ICU environments, with Confusion Assessment Method (CAM-ICU) scores measured each shift. We then performed logistic regression analysis, adjusting for possible confounding variables. Lower morning sound averages (8 am-12 pm) (OR = 0.835, 95% OR CI = [0.746, 0.934], p = 0.002) and higher daytime sound averages (12 pm-6 pm) (OR = 1.157, 95% OR CI = [1.036, 1.292], p = 0.011) were associated with an increased odds of delirium incidence, while nighttime sound averages (10 pm-8 am) (OR = 0.990, 95% OR CI = [0.804, 1.221], p = 0.928) and the ICU light environment did not show statistical significance. Our results suggest an association between the ICU soundscape and the odds of developing delirium. This creates a future paradigm for studies of the ICU soundscape and lightscape.

Observational Study of Clinician Attentional Reserves (OSCAR): Acuity-Based Rounds Help Preserve Clinicians' Attention.

OBJECTIVES: Team rounding in the ICU can tax clinicians' finite attentional resources. We hypothesized that a novel approach to rounding, where patients are seen in a decreasing order of acuity, would decrease attentional attrition. DESIGN: Prospective interventional internal-control cohort study in which stop signal task testing was used as a proxy for attentional reserves. Stop signal task is a measure of cognitive control and response inhibition in addition to performance monitoring, all reflective of executive control abilities, and our surrogate for attentional reserves. SETTING: The ICUs of Vanderbilt University Medical Center (site 1) and the University of Pennsylvania (site 2) from November 2014 to August 2017. SUBJECTS: Thirty-three clinicians at site 1, and 24 clinicians at site 2. INTERVENTIONS: Acuity-based rounding, in which clinicians round from highest to lowest acuity as determined by Sequential Organ Failure Assessment score or an equivalent acuity score. MEASUREMENTS AND MAIN RESULTS: The stop signal task results of ICU staff at two sites were compared for conventional (in room order) versus novel (in decreasing order of acuity) rounding order. At site 1, the difference in stop signal reaction time change between two rounding types was -39.0 ms (95% CI, -50.6 to -27.4 ms; p < 0.001), and at site 2, the performance stop signal reaction time was -15.6 ms (95% CI, -29.1 to -2.1 ms; p = 0.023). These sub-second changes, while small, are significant in the neuroscience domain. CONCLUSIONS: Rounding in decreasing order of patient acuity mitigated attrition in attentional reserves when compared with the traditional rounding method.

SAVIOR ICU: sonification and vibrotactile interface for the operating room and intensive care unit.

Alarm fatigue is an issue for healthcare providers in the intensive care unit, and may result from desensitization of overbearing and under-informing alarms. To directly increase the overall identification of medical alarms and potentially contribute to a downstream decrease in the prevalence of alarm fatigue, we propose advancing alarm sonification by combining auditory and tactile stimuli to create a multisensory alarm. Participants completed four trials-two multisensory (auditory and tactile) and two unisensory (auditory). Analysis compared the unisensory trials to the multisensory trials based on the percentage of correctly identified point of change, direction of change and identity of three physiological parameters (indicated by different instruments): heart rate (drums), blood pressure (piano), blood oxygenation (guitar). A repeated-measures of ANOVA yielded a significant improvement in performance for the multisensory group compared to the unisensory group (p < 0.05). Specifically, the multisensory group had better performance in correctly identifying parameter (p < 0.05) and point of change (p < 0.05) compared to the unisensory group. Participants demonstrated a higher accuracy of identification with the use of multisensory alarms. Therefore, multisensory alarms may relieve the auditory burden of the medical environment and increase the overall quality of care and patient safety.

What's all that noise-Improving the hospital soundscape.

Hospital noise levels regularly exceed those recommended by the World Health Organization (WHO). It is uncertain whether high noise levels have adverse effects on patient health. High levels of noise increase patient sleep loss, anxiety levels, length of hospital stay, and morbidity rates. Staff conversation and auditory medical alarms are amongst the leading noise producing stimuli, with combinations of stimuli accounting for much of the high noise levels. The Hospital Consumer Assessment of Healthcare Providers and Systems survey shows a slight improvement in overall hospital noise levels in the United States, indicating a minor reduction in noise levels. Alarm ambiguity, alarm masking and inefficient alarm design contributes to a large portion of sounds that exceed the environmental noise level in the hospital. Improving the hospital soundscape can begin by training staff in noise reduction, enforcing noise reduction programs, reworking alarm design and encouraging research to evaluate the relative effects of noise producing stimuli on the hospital soundscape.

Acoustic features of auditory medical alarms-An experimental study of alarm volume.

Audible alarms are a ubiquitous feature of all high-paced, high-risk domains such as aviation and nuclear power where operators control complex systems. In such settings, a missed alarm can have disastrous consequences. It is conventional wisdom that for alarms to be heard, "louder is better," so that alarm levels in operational environments routinely exceed ambient noise levels. Through a robust experimental paradigm in an anechoic environment to study human response to audible alerting stimuli in a cognitively demanding setting, akin to high-tempo and high-risk domains, clinician participants responded to patient crises while concurrently completing an auditory speech intelligibility and visual vigilance distracting task as the level of alarms were varied as a signal-to-noise ratio above and below hospital background noise. There was little difference in performance on the primary task when the alarm sound was -11 dB below background noise as compared with +4 dB above background noise-a typical real-world situation. Concurrent presentation of the secondary auditory speech intelligibility task significantly degraded performance. Operator performance can be maintained with alarms that are softer than background noise. These findings have widespread implications for the design and implementation of alarms across all high-consequence settings.

Classifying Alarms: Seeking Durability, Credibility, Consistency, and Simplicity.

Alongside the development and testing of new audible alarms intended to support International Electrotechnical Commission 60601-1-8, a global standard concerned with alarm safety, the categories of risk that the standard denotes require further thought and possible updating. In this article, we revisit the origins of the categories covered by the standard. These categories were based on the ways that tissue damage can be caused. We consider these categories from the varied professional perspectives of the authors: human factors, semiotics, clinical practice, and the patient or family (layperson). We conclude that while the categories possess many clinically applicable and defensible features from our range of perspectives, the advances in alarm design now available may allow a more flexible approach. We present a three-tier system with superordinate, basic, and subordinate levels that fit both within the thinking embodied in the current standard and possible new developments.

Intravenous warfarin and heparin-induced thrombocytopenia: making the diagnosis, management, modern monitoring, and multidisciplinary care.

OBJECTIVE: To describe the diagnosis, management, and monitoring of a patient with heparin-induced thrombocytopenia (HIT) with thrombosis and simultaneous bleeding risk treated with argatroban and transitioned to intravenous (IV) warfarin secondary to the inability to administer enteral medications. CASE SUMMARY: A 71-year-old man was admitted to the surgical intensive care unit (SICU) following aortic valve repair, coronary artery bypass, and ascending aortic aneurysm repair. On postoperative day 9, he was found to have a pulmonary embolism, and therapeutic heparin was started. The following day, his platelet count was found to have dropped precipitously. HIT was diagnosed, heparin was discontinued, and argatroban was initiated. On postoperative day 22, anticoagulation was discontinued because of massive gastrointestinal bleeding. On postoperative day 35, multiple venous thromboses were found, and argatroban was restarted. The patient developed a high-output enterocutaneous fistula, eliminating the option of enteral route of medication administration. The multidisciplinary SICU team transitioned the patient from argatroban to IV warfarin for long-term anticoagulation. The international normalized ratio was monitored and remained therapeutic throughout his admission without further thrombotic complications. DISCUSSION: HIT occurs when antibodies develop to heparin-platelet factor 4 complexes, causing simultaneous hypercoagulability and thrombocytopenia. It is diagnosed based on both clinical factors and laboratory testing. Treatment includes discontinuation of all forms of heparin; initiation of a nonheparin anticoagulant, such as argatroban; and transition to warfarin. CONCLUSIONS: IV warfarin is a therapeutic option for patients with malabsorption issues. A multidisciplinary team in an intensive care setting optimizes cost-effective, patient-centered, and safe care.

Improving pulse oximetry pitch perception with multisensory perceptual training.

The pulse oximeter is a critical monitor in anesthesia practice designed to improve patient safety. Here, we present an approach to improve the ability of anesthesiologists to monitor arterial oxygen saturation via pulse oximetry through an audiovisual training process. Fifteen residents' abilities to detect auditory changes in pulse oximetry were measured before and after perceptual training. Training resulted in a 9% (95% confidence interval, 4%-14%, P = 0.0004, t(166) = 3.60) increase in detection accuracy, and a 72-millisecond (95% confidence interval, 40-103 milliseconds, P < 0.0001, t(166) = -4.52) speeding of response times in attentionally demanding and noisy conditions that were designed to simulate an operating room. This study illustrates the benefits of multisensory training and sets the stage for further work to better define the role of perceptual training in clinical anesthesiology.