http://erg.sagepub.com/Factors ApplicationsErgonomics in Design: The Quarterly of Human http://erg.sagepub.com/content/20/2/4The online version of this article can be found at: DOI: 10.1177/1064804611435652 2012 20: 4Ergonomics in Design: The Quarterly of Human Factors ApplicationsMary Carol Day and Christopher Young''This is your heart speaking. Call 911.'' Published by: http://www.sagepublications.comOn behalf of: Human Factors and Ergonomics Society can be found at:Ergonomics in Design: The Quarterly of Human Factors ApplicationsAdditional services and information for http://erg.sagepub.com/cgi/alertsEmail Alerts: http://erg.sagepub.com/subscriptionsSubscriptions: http://www.sagepub.com/journalsReprints.navReprints: http://www.sagepub.com/journalsPermissions.navPermissions: http://erg.sagepub.com/content/20/2/4.refs.htmlCitations: What is This? - Apr 20, 2012Version of Record >> at HFES-Human Factors and Ergonomics Society on April 24, 2012erg.sagepub.comDownloaded fromergonomics in design | April 20124 “This is your heart speaking. Call 911.”Implantable vibrotactile alarms show great potential as early warning devices to prevent damage and death from heart attacks.FEATURE AT A GLANCE: Early warning for heart attacks could save many lives. We conducted three studies to design and evaluate multimodal alarms and patient training for an implanted heart attack detector. An implanted device provided vibrotactile alarms subcutaneously, and a pager-like device provided auditory and visual alarms. Temporal alarm patterns connoted an urgent emergency alarm (“Call 911”) and a less urgent alarm (“See your doctor”). In the third, clinical, study, most patients (94%) correctly responded to the alarms at 1, 3, and 6 months after device implantation. Subcutaneous vibrotactile alarms show great potential for use in critical medical applica-tions.KEYWORDS: medical devices, cardiac monitoring, vibration, perceived urgency, medical alarms, temporal alarm patternsBy Mary Carol Day & Christopher YoungAcute myocardial infarction is a leading cause of mortality in the United States. Annually, more than a million people experience a heart attack, and more than a third of those die before arriving at a hospital. The average symptom-to-hospital time of almost 3 hours has remained the same for more than a decade, despite multiple educational campaigns (e.g., Diercks et al., 2010; Gibson, 2001). Early warnings and elimination of uncertainty so that people seek immediate medical attention could save many lives and prevent heart damage.Medical progress has been unprecedented in the first decade of the current century. However, communication between medical technology (which tracks real-time physi-ological functions) and people (caregivers and patients) remains inadequate. Alarms and warnings have long been an important area of investigation for human factors/ergo-nomics specialists (Stanton, 1994). Research has increased greatly on the use of medical alarms, including vibrotactile alarms, for medical personnel in operating rooms and intensive care units (Edworthy & Hellier, 2006). Vibrotactile alarms, either alone or in combination with visual or auditory alarms, are not missed or ignored by medical staff as frequently as are visual or auditory alarms (e.g., Ng, Man, Fels, Dumant, & Ansermino, 2005).Far less research has focused on the use of alarms to warn patients of significant medical events. Advancing technology now enables 24-hour monitoring outside the hospital, so patients themselves (as well as doctors) can be warned of significant events. Because the alarm might occur at any time, an alert provided by an implanted medical device, unlike a portable device, could be especially beneficial.Auditory alarms are currently provided with some implantable cardioverter-defibrillators, but research has indicated that many patients do not hear the alarms, perhaps because of age-related hearing loss or ambient noise (Simons, Feigenblum, Nemirovsky, & Simons, 2009). Subcuta-neous vibrotactile alarms could be a viable alternative when used alone or in combina-tion with auditory alarms.Alarm design is critical because successful alerting, accurate patient identification of alarm type, and appropriate patient response can mean the difference between life and death. In this article, we describe human factors/ergonomics work on alarms for a medical device that is designed to alert high-risk cardiac patients about an impending or immediate heart attack (Fischell et al., 2010). The alarms are multimodal and provide redundant subcutaneous vibrotactile, audi-tory, and visual information. Here we briefly summarize three studies on the design and validation of subcutaneous vibrotactile patient alarms: (a) a study of alarm temporal patterns and vibrotactile magnitudes, (b) a study of learning and memory for the alarms, and (c) the initial clinical study with patients at high risk of a heart attack.DESIGN GOALS FOR THE ANGELMED GUARDIAN®The medical device described in this article (AngelMed Guardian®) offers two levels of alarm urgency. A high-priority alarm (“Emergency”) indicates that the patient may be having a heart attack and should call 911. A low-priority alarm (“See Doctor”) indicates that a condition has been feature at HFES-Human Factors and Ergonomics Society on April 24, 2012erg.sagepub.comDownloaded fromfeature | “This is your heart speaking. Call 911.”5 April 2012 | ergonomics in designdetected that requires a doctor visit within 48 hours (e.g., a device setting needs adjustment). Clearly, the Emergency alarm is more urgent than the See Doctor alarm. The alarms are provided by both an implanted medical device (IMD) similar in size to a pacemaker, which is placed in the upper left chest, and an external device (EXD), similar in size to a pager (Figure 1). The IMD continuously moni-tors the heart’s electrical activity. When it detects an alarm event, it vibrates in one of two temporal patterns, each corre-sponding to one of the alarms, and wirelessly communicates with the EXD. The EXD then emits an auditory alarm and flashes a red or yellow light-emitting diode (LED), labeled Emergency or See Doctor.Our primary goals were to design the Emergency and See Doctor alarms so that they (a) are perceptible (i.e., are felt and heard), (b) have distinct and identifiable temporal patterns, (c) have perceptual properties that connote their meaning (i.e., their level
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