Audibility and identification of auditory alarms in the operating room and intensive care unit

High visual salience of alert signals can lead to a counterintuitive increase of reaction times

It is often assumed that rendering an alert signal more salient yields faster responses to this alert. Yet, there might be a trade-off between attracting attention and distracting from task execution. Here we tested this in four behavioral experiments with eye-tracking using an abstract alert-signal paradigm. Participants performed a visual discrimination task (primary task) while occasional alert signals occurred in the visual periphery accompanied by a congruently lateralized tone. Participants had to respond to the alert before proceeding with the primary task. When visual salience (contrast) or auditory salience (tone intensity) of the alert were increased, participants directed their gaze to the alert more quickly. This confirms that more salient alerts attract attention more efficiently. Increasing auditory salience yielded quicker responses for the alert and primary tasks, apparently confirming faster responses altogether. However, increasing visual salience did not yield similar benefits: instead, it increased the time between fixating the alert and responding, as high-salience alerts interfered with alert-task execution. Such task interference by high-salience alert-signals counteracts their more efficient attentional guidance. The design of alert signals must be adapted to a "sweet spot" that optimizes this stimulus-dependent trade-off between maximally rapid attentional orienting and minimal task interference.

Attention Limitations in the Detection and Identification of Alarms in Close Temporal Proximity

OBJECTIVE

The aim of this study was to establish the effects of simultaneous and asynchronous masking on the detection and identification of visual and auditory alarms in close temporal proximity.

BACKGROUND

In complex and highly coupled systems, malfunctions can trigger numerous alarms within a short period of time. During such alarm floods, operators may fail to detect and identify alarms due to asynchronous and simultaneous masking. To date, the effects of masking on detection and identification have been studied almost exclusively for two alarms during single-task performance. This research examines 1) how masking affects alarm detection and identification in multitask environments and 2) whether those effects increase as a function of the number of alarms.

METHOD

Two experiments were conducted using a simulation of a drone-based package delivery service. Participants were required to ensure package delivery and respond to visual and auditory alarms associated with eight drones. The alarms were presented at various stimulus onset asynchronies (SOAs). The dependent measures included alarm detection rate, identification accuracy, and response time.

RESULTS

Masking was observed intramodally and cross-modally for visual and auditory alarms. The SOAs at which asynchronous masking occurred were longer than reported in basic research on masking. The effects of asynchronous and, even more so, simultaneous masking became stronger as the number of alarms increased.

CONCLUSION

Masking can lead to breakdowns in the detection and identification of alarms in close temporal proximity in complex data-rich domains.

APPLICATION

The findings from this research provide guidance for the design of alarm systems.

Fast & scrupulous: Gesture-based alarms improve accuracy and reaction times under various mental workload levels. An ERSP study

In high-risk environments, fast and accurate responses to warning systems are essential to efficiently handle emergency situations. The aim of the present study was twofold: 1) investigating whether hand action videos (i.e., gesture alarms) trigger faster and more accurate responses than text alarm messages (i.e., written alarms), especially when mental workload (MWL) is high; and 2) investigating the brain activity in response to both types of alarms as a function of MWL. Regardless of MWL, participants (N = 28) were found to be both faster and more accurate when responding to gesture alarms than to written alarms. Brain electrophysiological results suggest that this greater efficiency might be due to a facilitation of the action execution, reflected by the decrease in mu and beta power observed around the response time window observed at C3 and C4 electrodes. These results suggest that gesture alarms may improve operators' performances in emergency situations.

Masking Between Reserved Alarm Sounds of the IEC 60601-1-8 International Medical Alarm Standard: A Systematic, Formal Analysis

OBJECTIVE

In this work, we systematically evaluated the reserved alarm sounds of the IEC 60601-1-8 international medical alarm standard to determine when and how they can be totally and partially masked.

BACKGROUND

IEC 60601-1-8 gives engineers instruction for creating human-perceivable auditory medical alarms. This includes reserved alarm sounds: common types of alarms where each is a tonal melody. Even when this standard is honored, practitioners still fail to hear alarms, causing practitioner nonresponse and, thus, potential patient harm. Simultaneous masking, a condition where one or more alarms is imperceptible in the presence of other concurrently sounding alarms due to limitations of the human sensory system, is partially responsible for this.

METHODS

In this research, we use automated proof techniques to determine if masking can occur in a modeled configuration of medical alarms. This allows us to determine when and how reserved alarm sound can mask other reserved alarms and to explore parameters to address discovered problems.

RESULTS

We report the minimum number of other alarm sounds it takes to both totally and partially mask each of the high-, medium-, and low-priority alarm sounds from the standard.

CONCLUSIONS

Significant masking problems were found for both the total and partial masking of high-, medium-, and low-priority reserved alarm sounds.

APPLICATION

We show that discovered problems can be mitigated by setting alarm volumes to standard values based on priority level and by randomizing the timing of alarm tones.

Investigating Cognitive Load in Energy Network Control Rooms: Recommendations for Future Designs

This study analyzed and explored the cognitive load of Australian energy market operators managing one of the longest inter-connected electrical networks in the world. Each operator uses a workstation with seven screens in an active control room environment, with a large coordination screen to show information and enable collaboration between different control centers. Cognitive load was assessed during both training scenarios and regular control room operations via the integration of subjective and physiological measures. Eye-tracking glasses were also used to analyze the operators gaze behavior. Our results indicate that different events (normal or unexpected), different participants for the same session, and different periods of one session all have varying degrees of cognitive load. The system design was observed to be inefficient in some situations and to have an adverse affect on cognitive load. In critical situations for instance, operator collaboration was high and the coordination screen was used heavily when collaborating between two control centers, yet integration with the system could be improved. Eye tracking data analysis showed that the layout of applications across the seven screens was not optimal for many tasks. Improved layout strategies, potential combination of applications, redesigning of certain applications, and linked views are all recommended for further exploration in addition to improved integration of procedures and linking alarms to visual cues.

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.

Nurses' use of auditory alarms and alerts in high dependency units: A field study

A fieldwork study conducted in six units of a major metropolitan Australian hospital revealed that nurses' attitudes towards alarms are influenced by each unit's physical layout and caseload. Additionally, nurses relied heavily on both non-actionable and actionable alarms to maintain their awareness of the status of their patients' wellbeing, and used auditory alarms beyond the scope of their intended design. Results suggest that before reducing or removing auditory alarms from the clinical environment to improve patient safety, it is important to understand how nurses in different clinical contexts use current alarm systems to extract meaningful information. Such an understanding could guide appropriate alarm reduction strategies and guide alternative design solutions to support nurses' situation awareness during monitoring.

Re-Sounding Alarms: Designing Ergonomic Auditory Interfaces by Embracing Musical Insights

Auditory alarms are an important component of human–computer interfaces, used in mission-critical industries such as aviation, nuclear power plants, and hospital settings. Unfortunately, problems with recognition, detection, and annoyance continue to hamper their effectiveness. Historically, they appear designed more in response to engineering constraints than principles of hearing science. Here we argue that auditory perception in general and music perception in particular hold valuable lessons for alarm designers. We also discuss ongoing research suggesting that the temporal complexity of musical tones offers promising insight into new ways of addressing widely recognized shortcomings of current alarms.

An Experimental Validation of Masking in IEC 60601-1-8:2006-Compliant Alarm Sounds

OBJECTIVE

This research investigated whether the psychoacoustics of simultaneous masking, which are integral to a model-checking-based method, previously developed for detecting perceivability problems in alarm configurations, could predict when IEC 60601-1-8-compliant medical alarm sounds are audible.

BACKGROUND

The tonal nature of sounds prescribed by IEC 60601-1-8 makes them potentially susceptible to simultaneous masking: where concurrent sounds render one or more inaudible due to human sensory limitations. No work has experimentally assessed whether the psychoacoustics of simultaneous masking accurately predict IEC 60601-1-8 alarm perceivability.

METHOD

In two signal detection experiments, 28 nursing students judged whether alarm sounds were present in collections of concurrently sounding standard-compliant tones. The first experiment used alarm sounds with single-frequency (primary harmonic) tones. The second experiment's sounds included the additional, standard-required frequencies (often called subharmonics). T tests compared miss, false alarm, sensitivity, and bias measures between masking and nonmasking conditions and between the two experiments.

RESULTS

Miss rates were significantly higher and sensitivity was significantly lower for the masking condition than for the nonmasking one. There were no significant differences between the measures of the two experiments.

CONCLUSION

These results validate the predictions of the psychoacoustics of simultaneous masking for medical alarms and the masking detection capabilities of our method that relies on them. The results also show that masking of an alarm's primary harmonic is sufficient to make an alarm sound indistinguishable.

APPLICATION

Findings have profound implications for medical alarm design, the international standard, and masking detection methods.

Using timbre to improve performance of larger auditory alarm sets

Identifiability and perceived urgency were compared for two sets of alarms in a healthcare inpatient setting. One contained currently used alarms where possible, with new sounds added as needed. The other was designed together, was more heterogenous, used timbre to encode intended similarities and explicitly encoded intended urgency across the set. Twenty nurses reported the identity and perceived urgency of the sounds in each set. Participants correctly identified the sound (0.89 vs. 0.77) and alarm category (0.93 vs. 0.82) more often in the new set than in the baseline set. In addition, multiple sounds in the new set were more identifiable. The new sounds also had a larger range of perceived urgency and better urgency match. The results indicate that timbre is well-suited to encode alarm groupings in larger alarm sets and that this, along with increased heterogeneity and explicit urgency mapping, improves alarm set performance. Practitioner summary: Clinical alarms are frequently misidentified. We found that making alarms more acoustically rich, using timbre to convey alarm groups, and explicitly encoding intended urgency improved identifiability and urgency match. These findings can be used to improve alarm performance across all safety-critical industries.

How Well Can Anaesthetists Discriminate Pulse Oximeter Tones?

The ability of experienced anaesthetists to discern oxygen saturation by listening to the tones of a Datex AS3 pulse oximeter was examined. Five-second samples were recorded using a high fidelity patient simulator and replayed singly and in pairs. Whilst the lower saturations were generally recognized as lower, the perceived range was greatly compressed. Median perceived estimates for 70% saturation was 89%, for 80% was 93% and for 94% was 94%. When comparing pairs of samples, the direction of the difference was correctly discerned by 70% of anaesthetists for differences of 2%, rising to 95% for differences of greater than 8% oxygen saturation. The magnitude of the difference was consistently underestimated. With an actual difference of 20%, the median estimate was 5%. The results indicate that while qualitative estimate changes in oxygen saturation are moderately reliable, quantitative estimation is severely limited by a compromised perceived scale. This may lead to underestimation of the severity if the auditory signal is relied on in isolation. A non-linear (musical) scale may prove more appropriate and should be investigated. Testing experienced anaesthetists demonstrated that most could detect the direction, but not the magnitude of a change in saturation by listening to the change in pitch of a Datex AS3 pulse oximeter tone.

A Formal Analysis of Masking Between Reserved Alarm Sounds of the IEC 60601-1-8 International Medical Alarm Standard

The IEC 60601-1-8 international medical alarm standard was created to give engineers guidance for designing alarms that are easily perceivable by humans. Included within this are a number of reserved alarm sounds that use tonal melodies to represent common types of alarms. Despite the standard, practitioners can still fail to hear and respond to alarms. This can have a profound negative impact on patient life and health. One of the factors that contributes to this problem is simultaneous masking: a condition where one or more alarms can be rendered imperceptible in the presence of other alarms due to limitations of the human perception system. Unfortunately, the tonal nature of the IEC 60601-1-8 reserved sounds makes them particularly susceptible to masking. It can be difficult to determine how masking can manifest in a collection of alarms that can sound concurrently given the inherent complexity of the statespace. In this work, we employ a computational method that employs mathematical proof techniques to determine if masking is possible in a model of a configuration of medical alarms. We use this to analyze the low and medium priority reserved alarm sounds of the IEC 60601-1-8 standard. We describe our method, present the results of our analyses, discuss these results, and explore future research directions.

Understanding Clinical Alarm Safety

Patient safety organizations and health care accreditation agencies recognize the significance of clinical alarm hazards. The Association for the Advancement of Medical Instrumentation, a nonprofit organization focused on development and use of safe and effective medical equipment, identifies alarm management as a major issue for health care organizations. ECRI Institute, a nonprofit organization that researches approaches for improving patient safety and quality of care, identifies alarm hazards as the most significant of the "Top Ten Health Technology Hazards" for 2014. A new Joint Commission National Patient Safety Goal focusing on clinical alarm safety contains new requirements for accredited hospitals to be fully implemented by 2016. Through a fictional unfolding case study, this article reviews selected contributing factors to clinical alarm hazards present in inpatient, high-acuity settings. Understanding these factors improves contributions by nurses to clinical alarm safety practice.

A formal approach to discovering simultaneous additive masking between auditory medical alarms

The failure of humans to respond to auditory medical alarms has resulted in numerous patient injuries and deaths and is thus a major safety concern. A relatively understudied source of response failures has to do with simultaneous masking, a condition where concurrent sounds interact in ways that make one or more of them imperceptible due to physical limitations of human perception. This paper presents a method, which builds on a previous implementation, that uses a novel combination of psychophysical modeling and formal verification with model checking to detect masking in a modeled configuration of medical alarms. Specifically, the new method discussed here improves the original method by adding the ability to detect additive masking while concurrently improving method usability and scalability. This paper describes how these additions to our method were realized. It then demonstrates the scalability and detection improvements via three different case studies. Results and future research are discussed.

Anesthesia Alarms in Surgical Context

This paper describes an observational study of anesthetists' response to alarms in the operating room across four different types of procedure (laparoscopic, arthroscopic, cardiac, and intracranial) and three phases of a procedure (induction, maintenance, and emergence). Alarms were classified as requiring a corrective response, being intended, being ignored, or functioning as a reminder. Results revealed quite strong effects of the type of procedure and phase of procedure on the number and rate of alarms. Responses to alarms such as apnea varied strongly across phase, whereas other alarms were confined to specific situations. These results were interpreted in light of their significance for the development of smart alarm systems.

An Application of Auditory Alarm Research in the Design of Warning Sounds for an Integrated Tower Air Traffic Control Computer System

Auditory alarms are often determined by different manufacturers in isolation without any guidelines or standards. The result is an environment filled with inconsistent, confusing, meaningless, and often annoying alarm sounds. Such factors have been considered in the design of a Tower Air Traffic Control computer system (referred to as TCCC) currently under contract with the Federal Aviation Administration (FAA), which will serve to integrate and standardize the various systems in the tower. One of the many benefits of this new automation will be that the warning sounds in use today will be replaced with standard, ergonomically designed alarm sounds. This paper follows the process the authors used in constructing TCCC auditory alarms, combining a detailed analysis of the common problems associated with auditory alarms with a review of alarm construction theories and standards. The results of this process, the proposed TCCC auditory alarm attributes, are then presented.

An Analysis of Problems with Auditory Alarms: Defining the Roles of Alarms in Process Monitoring Tasks

It has become a standard practice to use auditory alarm devices to enhance human monitoring performance in monitoring tasks. However, the effectiveness of such practice has been-challenged from time to time, which leads to the fundamental question of what roles alarms should and could assume. This paper reviews reported observations of interactions between human operators and alarm mechanisms in patient care, aviation, and process control. Based on the reviews, we propose that the roles of alarms in process monitoring tasks should be viewed more as a way of informing process status and less as a way of interpreting the significance of process status. The roles can best be understood in the skill-, rule-, and knowledge-based performance framework. Implications to alarm and auditory designs are discussed. Specifically, design of alarm devices should be guided by the principle of information provision regardless of whether an alarm may be true or false indication of “alarming” events.

Using Model Checking to Detect Masking in IEC 60601-1-8-compliant Alarm Configurations

The failure of humans to respond to auditory medical alarms has resulted in numerous patient injuries and deaths. The widely used IEC 60601-1-8 international medical alarm standard was created to improve alarm discernibility and identification. Unfortunately, the melodic tonal patterns of IEC 60601-1-8’s alarms are particularly susceptible to simultaneous masking, a condition where concurrent sounds interact in ways that make one or more of them imperceptible. This paper presents a method, which builds on a previous implementation, that uses a novel combination of psychophysical modeling and model checking to detect masking in a modeled configuration of IEC 60601-1-8 alarms. We describe our updated method and demonstrate its power by using it to find masking in the alarms of an actual IEC 60601-1-8-compliant telemetry monitoring system. Results and future research are discussed.

A human factors perspective on medical device alarms: problems with operating alarming devices and responding to device alarms

Medical devices emit alarms when a problem with the device or with the patient needs to be addressed by healthcare personnel. At present, problems with device alarms are frequently discussed in the literature, the main message being that patient safety is compromised because device alarms are not as effective and safe as they should - and could - be. There is a general consensus that alarm-related hazards result, to a considerable degree, from the interactions of human users with the device. The present paper addresses key aspects of human perception and cognition that may relate to both operating alarming devices and responding to device alarms. Recent publications suggested solutions to alarm-related hazards associated with usage errors based on assumptions on the causal relations between, for example, alarm management and human perception, cognition, and responding. However, although there is face validity in many of these assumptions, future research should provide objective empirical evidence in order to deepen our understanding of the actual causal relationships, and hence improve and expand the possibilities for taking appropriate action.

Clinical Alarms in Intensive Care Units: Perceived Obstacles of Alarm Management and Alarm Fatigue in Nurses

OBJECTIVES

The purpose of this descriptive study was to investigate the current situation of clinical alarms in intensive care unit (ICU), nurses' recognition of and fatigue in relation to clinical alarms, and obstacles in alarm management.

METHODS

Subjects were ICU nurses and devices from 48 critically ill patient cases. Data were collected through direct observation of alarm occurrence and questionnaires that were completed by the ICU nurses. The observation time unit was one hour block. One bed out of 56 ICU beds was randomly assigned to each observation time unit.

RESULTS

Overall 2,184 clinical alarms were counted for 48 hours of observation, and 45.5 clinical alarms occurred per hour per subject. Of these, 1,394 alarms (63.8%) were categorized as false alarms. The alarm fatigue score was 24.3 ± 4.0 out of 35. The highest scoring item was "always get bothered due to clinical alarms". The highest scoring item in obstacles was "frequent false alarms, which lead to reduced attention or response to alarms".

CONCLUSIONS

Nurses reported that they felt some fatigue due to clinical alarms, and false alarms were also obstacles to proper management. An appropriate hospital policy should be developed to reduce false alarms and nurses' alarm fatigue.

Simulating environmental and psychological acoustic factors of the operating room

In this study, an operating room simulation environment was adapted to include quadraphonic speakers, which were used to recreate a composed clinical soundscape. To assess validity of the composed soundscape, several acoustic parameters of this simulated environment were acquired in the presence of alarms only, background noise only, or both. These parameters were also measured for comparison from size-matched operating rooms at Jackson Memorial Hospital. The parameters examined included sound level, reverberation time, and predictive metrics of speech intelligibility in quiet and noise. It was found that the sound levels and acoustic parameters were comparable between the simulated environment and the actual operating rooms. The impact of the background noise on the perception of medical alarms was then examined, and was found to have little impact on the audibility of the alarms. This study is a first in kind report of a comparison between the environmental and psychological acoustical parameters of a hospital simulation environment and actual operating rooms.

Alarm system management: evidence-based guidance encouraging direct measurement of informativeness to improve alarm response

Although there are powerful incentives for creating alarm management programmes to reduce 'alarm fatigue', they do not provide guidance on how to reduce the likelihood that clinicians will disregard critical alarms. The literature cites numerous phenomena that contribute to alarm fatigue, although many of these, including total rate of alarms, are not supported in the literature as factors that directly impact alarm response. The contributor that is most frequently associated with alarm response is informativeness, which is defined as the proportion of total alarms that successfully conveys a specific event, and the extent to which it is a hazard. Informativeness is low across all healthcare applications, consistently ranging from 1% to 20%. Because of its likelihood and strong evidential support, informativeness should be evaluated before other contributors are considered. Methods for measuring informativeness and alarm response are discussed. Design directions for potential interventions, as well as design alternatives to traditional alarms, are also discussed. With the increased attention and investment in alarm system management that alarm interventions are currently receiving, initiatives that focus on informativeness and the other evidence-based measures identified will allow us to more effectively, efficiently and reliably redirect clinician attention, ultimately improving alarm response.

An Approach to Model Checking the Perceptual Interactions of Medical Alarms

The perceptibiliy of auditory medical alarms is critical to patient health and safety. Unfortunately concurrently sounding alarms can interact in ways that can mask one or more of them: render them imperceptible. Masking may only occur in extremely specific and/or rare situations. Thus, experimentation is insufficient for detecting it in all of the potential alarm configurations used in medicine. Therefore, there is a real need for computational methods capable of determining if masking exists in medical alarm configurations. In this work, we present such a method. Using a combination of formal modeling, psychoacoustic modeling, temporal logic specification, and model checking, our method is able to prove whether a configuration of alarms can interact in a way that produces masking. This paper motivates and presents this method, describes its implementation, demonstrates its power with an application, and outlines future developments.

Learning three sets of alarms for the same medical functions: a perspective on the difficulty of learning alarms specified in an international standard

Three sets of eight alarms supporting eight functions specified in an international medical equipment standard (IEC 60601-1-8) were tested for learnability using non-anaesthetist participants. One set consisted of the tonal alarms specified in the standard. A second set consisted of a set of abstract alarms randomly selected from a database of abstract alarm sounds held by the authors. A third set of alarms was designed as indirect metaphors of the functions. Participants were presented with the alarms and then asked to identify them across ten blocks of eight trials. The results indicated a significant difference in learnability across the three sets of alarms. The indirect metaphors were learned significantly better than both other sets of alarms, and the randomly selected abstract alarms were learned significantly better than the alarms specified in the standard. The results suggest therefore that there are more readily learnable possible designs than those proposed in the standard. The use of auditory icons in particular should be given serious consideration as potential alarms for this application.

Evaluation of a configural vital signs display for intensive care unit nurses

OBJECTIVE

The objective was to evaluate a configural vital signs (CVS) display designed to support rapid detection and identification of physiological deterioration by graphically presenting patient vital signs data.

BACKGROUND

Current display technology in the intensive care unit (ICU) is not optimized for fast recognition and identification of physiological changes in patients. To support nurses more effectively, graphical or configural vital signs displays need to be developed and evaluated.

METHOD

A CVS display was developed based on findings from studies of the cognitive work of ICU nurses during patient monitoring. A total of 42 ICU nurses interpreted data presented either in a traditional, numerical format (n = 21) or on the CVS display (n = 21). Response time and accuracy in clinical data interpretation (i.e., identification of patient status) were assessed across four scenarios.

RESULTS

Data interpretation speed and accuracy improved significantly in the CVS display condition; for example, in one scenario nurses required only half of the time for data interpretation and showed up to 1.9 times higher accuracy in identifying the patient state compared to the numerical display condition.

CONCLUSION

Providing patient information in a configural display with readily visible trends and data variability can improve the speed and accuracy of data interpretation by ICU nurses.

APPLICATION

Although many studies, including this one, support the use of configural displays, the vast majority of ICU monitoring displays still present clinical data in numerical format. The introduction of configural displays in clinical monitoring has potential to improve patient safety.

[Reaction time of a health care team to monitoring alarms in the intensive care unit: implications for the safety of seriously ill patients]

OBJECTIVE

To define the characteristics and measure the reaction time of a health care team monitoring alarms in the intensive care unit.

METHODS

A quantitative, observational, and descriptive study developed at the coronary care unit of a cardiology public hospital in Rio de Janeiro state (RJ). Data were obtained from the information collected on the patients, the monitoring used, and the measurement of the team's reaction time to the alarms of multi-parameter monitors during a non-participatory field observation.

RESULTS

Eighty-eight patients were followed (49 during the day shift and 39 during the night shift). During the 40 hours of observation (20 hours during the day shift and 20 hours during the night shift), the total number of monitoring alarms was 227, with 106 alarms during the day shift and 121 during the night shift, an average of 5.7 alarms/hour. In total, 145 alarms unanswered by the team were observed, with 68 occurring during the day shift (64.15%) and 77 during the night shift (63.64%). This study demonstrated that the reaction time was longer than 10 minutes in more than 60% of the alarms, which were considered as unanswered alarms. The median reaction time of the answered alarms was 4 minutes and 54 seconds during the day shift and 4 minutes and 55 seconds during the night shift. The respiration monitoring was activated in only nine patients (23.07%) during the night shift. Regarding the alarm quality of these variables, the arrhythmia alarm was qualified in only 10 (20.40%) of the day-shift patients and the respiration alarm in four night-shift patients (44.44%).

CONCLUSION

The programming and configuration of the physiological variables monitored and the parameters of alarms in the intensive care unit were inadequate; there was a delay and lack of response to the alarms, suggesting that relevant alarms may have been ignored by the health care team, thus compromising the patient safety.

Improving the hospital 'soundscape': a framework to measure individual perceptual response to hospital sounds

Work on the perception of urban soundscapes has generated a number of perceptual models which are proposed as tools to test and evaluate soundscape interventions. However, despite the excessive sound levels and noise within hospital environments, perceptual models have not been developed for these spaces. To address this, a two-stage approach was developed by the authors to create such a model. First, semantics were obtained from listening evaluations which captured the feelings of individuals from hearing hospital sounds. Then, 30 participants rated a range of sound clips representative of a ward soundscape based on these semantics. Principal component analysis extracted a two-dimensional space representing an emotional-cognitive response. The framework enables soundscape interventions to be tested which may improve the perception of these hospital environments.

Human Factors in Critical Care Medical Environments

The purpose of this chapter on human factors in critical care medical environments is to provide a systematic review of the human factors and ergonomics contributions that led to significant improvements in patient safety over the last five decades. The review will focus on issues that contributed to patient injury and fatalities and how human factors and ergonomics can improve performance of providers in critical care. Given the complexity of critical care delivery, a review needs to cover a wide range of subjects. In this review, I take a sociotechnical systems perspective on critical care and discuss the people, their technical and nontechnical skills, the importance of teamwork, technology, and ergonomics in this complex environment. After a description of the importance of a safety climate, the chapter will conclude with a summary on how human factors and ergonomics can improve quality in critical care delivery.

Learning medical alarms whilst performing other tasks

Two studies are reported which first observe, and then attempt to replicate, the cognitive demands of intensive care unit (ICU) activity whilst concurrently learning audible alarms. The first study, an observational study in an ICU ward, showed that the alarms are very frequent and co-occur with some activities more than others. The three most frequently observed activities observed in the ICU were drugs (calculation, preparation and administration), patient observation and talking. The cognitive demands of these activities were simulated in a second, laboratory-based experiment in which alarms were learned. The results showed that performance in the alarm task generally improved as participants were exposed to more repetitions of those alarms, but that performance decrements were observed in the secondary tasks, particularly when there were two or three of them. Some confusions between the alarms persisted to the end of the study despite prolonged exposure to the alarms, confusions which were likely caused by both acoustic and verbal labelling similarities.

PRACTITIONER SUMMARY

The cognitive demands of working in an ICU were observed and simulated whilst alarms were learned. Alarms should generally avoid sharing similar rhythmic (and other) characteristics. The simulation task described here could be used for testing alarm learning without requiring a clinical environment.

Medical audible alarms: a review

OBJECTIVES

This paper summarizes much of the research that is applicable to the design of auditory alarms in a medical context. It also summarizes research that demonstrates that false alarm rates are unacceptably high, meaning that the proper application of auditory alarm design principles are compromised.

TARGET AUDIENCE

Designers, users, and manufacturers of medical information and monitoring systems that indicate when medical or other parameters are exceeded and that are indicated by an auditory signal or signals.

SCOPE

The emergence of alarms as a 'hot topic'; an outline of the issues and design principles, including IEC 60601-1-8; the high incidence of false alarms and its impact on alarm design and alarm fatigue; approaches to reducing alarm fatigue; alarm philosophy explained; urgency in audible alarms; different classes of sound as alarms; heterogeneity in alarm set design; problems with IEC 60601-1-8 and ways of approaching this design problem.

Reducing hospital noise: a review of medical device alarm management

Increasing noise in hospital environments, especially in intensive care units (ICUs) and operating rooms (ORs), has created a formidable challenge for both patients and hospital staff. A major contributing factor for the increasing noise levels in these environments is the number of false alarms generated by medical devices. This study focuses on discovering best practices for reducing the number of false clinical alarms in order to increase patient safety and provide a quiet environment for both work and healing. The researchers reviewed Pub Med, Web of Knowledge and Google Scholar sources to obtain original journal research and review articles published through January 2012. This review includes 27 critically important journal articles that address different aspects of medical device alarms management, including the audibility, identification, urgency mapping, and response time of nursing staff and different solutions to such problems. With current technology, the easiest and most direct method for reducing false alarms is to individualize alarm settings for each patient's condition. Promoting an institutional culture change that emphasizes the importance of individualization of alarms is therefore an important goal. Future research should also focus on the development of smart alarms.

Anaesthesia monitor alarms: a theory-driven approach

The development of physiologic monitors has contributed to the decline in morbidity and mortality in patients undergoing anaesthesia. Diverse factors (physiologic, technical, historical and medico-legal) create challenges for monitor alarm designers. Indeed, a growing body of literature suggests that alarms function sub-optimally in supporting the human operator. Despite existing technology that could allow more appropriate design, most anaesthesia alarms still operate on simple, pre-set thresholds. Arguing that more alarms do not necessarily make for safer alarms is difficult in a litigious medico-legal environment and a competitive marketplace. The resultant commitment to the status quo exposes the risks that a lack of an evidence-based theoretical framework for anaesthesia alarm design presents. In this review, two specific theoretical foundations with relevance to anaesthesia alarms are summarised. The potential significance that signal detection theory and cognitive systems engineering could have in improving anaesthesia alarm design is outlined and future research directions are suggested.

PRACTITIONER SUMMARY

The development of physiologic monitors has increased safety for patients undergoing anaesthesia. Evidence suggests that the full potential of the alarms embedded within those monitors is not being realised. In this review article, the authors propose a theoretical framework that could lead to the development of more ergonomic anaesthesia alarms.

Alarm fatigue

The number of false high alarms in the hospital setting remains a serious problem. False alarms have desensitized care providers and, at times, have led to dire consequences for patients. Efforts by both industry and clinicians are beginning to address this situation in collaborative approaches. Research is needed to establish an evidence base around issues such as which patients need to be monitored, and what the threshold settings and delay settings should be on devices. Initial and ongoing education needs to be considered for any new medical device, and be included in the hospital's annual budget.

A vibro-tactile display for clinical monitoring: real-time evaluation

BACKGROUND

Vibro-tactile displays use human skin to convey information from physiological monitors to anesthesiologists, providing cues about changes in the status of the patient. In this investigation, we evaluated, in a real-time clinical environment, the usability and wearability of a novel vibro-tactile display belt recently developed by our group, and determined its accuracy in identifying events when used by anesthesiologists.

METHODS

A prospective observational study design was used. During routine anesthesia, a standard physiological monitor was connected to a software tool that used algorithms to automatically identify changing trends in mean noninvasive arterial blood pressure, expired minute ventilation, peak airway pressure, and end-tidal carbon dioxide partial pressure. The software was wirelessly interfaced to a vibro-tactile belt worn by the anesthesiologist. Each physiological variable was mapped to 1 of 4 tactor locations within the belt. The direction (increase/decrease) and 2 levels of change (small/large) were encoded in the stimulation patterns. A training session was completed by each anesthesiologist. The system was activated in real-time during anesthesia alongside routine physiological monitors. When the algorithms detected changes in the patient, the belt vibrated at the appropriate location with the pattern corresponding to the level and direction of change. Using a touch screen monitor the anesthesiologist was to enter the vibro-tactile message by first identifying the variable, then identifying the level and direction of change. Usability and wearability questionnaires were to be completed. The percentage of correct identification of the physiological trend, the direction of change, and the level of change were primary outcome variables. The mean usability score and wearability results were secondary outcome variables. We hypothesized that anesthesiologists would correctly identify the events communicated to them through the vibro-tactile belt 90% of the time, and that anesthesiologists would find the vibro-tactile belt usable and wearable.

RESULTS

Seventeen anesthesiologists evaluated the display during 57 cases. The belt was operational for a mean (SD) duration of 75 (41) minutes per case. Seven cases were excluded from analysis because of technical failures. Eighty-one percent (confidence interval [CI], 77% to 84%) of all stimuli were decoded. The physiological trend, the direction of change, and the level of change were correctly identified for 97.7% (CI 96%-99%), 94.9% (CI 92%-97%), and 93.5% of these stimuli (CI, 91%-96%), respectively. Fourteen anesthesiologists completed the usability and wearability questionnaires. The mean usability score was 4.8 of a maximum usability score of 7.

CONCLUSIONS

Anesthesiologists found a vibro-tactile belt to be wearable and usable and could accurately decode vibro-tactile messages in a real-time clinical environment.

Smart alarms from medical devices in the OR and ICU

Alarms in medical devices are a matter of concern in critical and perioperative care. The high rate of false alarms is not only a nuisance for patients and caregivers, but can also compromise patient safety and effectiveness of care. The development of alarm systems has lagged behind the technological advances of medical devices over the last 20 years. From a clinical perspective, major improvements in alarm algorithms are urgently needed. This review gives an overview of the current clinical situation and the underlying problems, and discusses different methods from statistics and computational science and their potential for clinical application. Some examples of the application of new alarm algorithms to clinical data are presented.

Designing informative warning signals: Effects of indicator type, modality, and task demand on recognition speed and accuracy

An experiment investigated the assumption that natural indicators which exploit existing learned associations between a signal and an event make more effective warnings than previously unlearned symbolic indicators. Signal modality (visual, auditory) and task demand (low, high) were also manipulated. Warning effectiveness was indexed by accuracy and reaction time (RT) recorded during training and dual task test phases. Thirty-six participants were trained to recognize 4 natural and 4 symbolic indicators, either visual or auditory, paired with critical incidents from an aviation context. As hypothesized, accuracy was greater and RT was faster in response to natural indicators during the training phase. This pattern of responding was upheld in test phase conditions with respect to accuracy but observed in RT only in test phase conditions involving high demand and the auditory modality. Using the experiment as a specific example, we argue for the importance of considering the cognitive contribution of the user (viz., prior learned associations) in the warning design process. Drawing on semiotics and cognitive psychology, we highlight the indexical nature of so-called auditory icons or natural indicators and argue that the cogniser is an indispensable element in the tripartite nature of signification.

Building Health

Biological and medical research offer rigorous techniques and scientific methodologies to explore how features of the built environment influence human health, performance, and well-being. Practice guidelines from evidence-based medicine and translational science provide models for translating biomedical information into design principles applicable to healthcare environments. Examples from recent scientific discoveries highlight how scientific evidence may inform healthcare design. The interaction between stress and environmental stimuli such as light, sound, and location are relevant to patients, visitors, and staff, influencing cardiac and stress responses as well as cognitive functions such as memory and navigation abilities. Research demonstrating the pervasive influence of light on human biological systems includes epidemiological and laboratory studies that suggest an association between light exposure and increased cardiac or cancer risk. Advances in laboratory research and the development of wearable devices that may be used on-site in healthcare settings facilitate more precise measurement of the environmental features that influence healthcare users and providers. The data derived may serve as the foundation for new evidence-based performance criteria, supporting the use of existing materials and methods, as well as the creation of new design solutions to meet health needs in addition to operational outcomes.