Academic journal article Human Factors

Anesthesia Alarms in Context: An Observational Study

Academic journal article Human Factors

Anesthesia Alarms in Context: An Observational Study

Article excerpt

This paper surveys current work on the design of alarms for anesthesia environments and notes some of the problems arising from the need to interpret alarms in context. Anesthetists' responses to audible alarms in the operating room were observed across four types of surgical procedure (laparoscopic, arthroscopic, cardiac, and intracranial) and across three phases of a procedure (induction, maintenance, and emergence). Alarms were classified as (a) requiring a corrective response, (b) being the intended result of a decision, (c) being ignored as a nuisance alarm, or (d) functioning as a reminder. Results revealed strong effects of the type of procedure and phase of procedure on the number and rate of audible alarms. Some alarms were relatively confined to specific phases; others were seen across phases, and responses differed according to phase. These results were interpreted in light of their significance for the development of effective alarm systems. Actual or potential applications of this research includ e the design of alarm systems that are more informative and more sensitive to operative context than are current systems.


Health care is increasingly drawing the attention of cognitive engineers and human-computer interaction researchers. Information technology is being introduced into a wide variety of medical devices and systems, such as patient physiological monitoring systems, anesthesia machines, respirators, home health care devices, and hospital and medical information systems. At the same time, such medical devices and systems are being used by a wider population, necessitating better interface design. These trends have led to a concern for human error in medicine (Bogner, 1994) as well as for developing guidelines and standards for the design of medical devices and systems.

Safe and effective human performance with medical devices and systems is essential. Yet the human operators of such systems are challenged not only by increasing device complexity but also by growth in the number of devices that have to be coordinated in a single work environment. This is particularly so in critical care environments such as the operating room (OR), the intensive care unit (ICU), and the emergency room (ER). Anesthetists are challenged by the fact that anesthetic drugs now have a more rapid onset, higher potency, and faster emergence, making swifter responses to changing and potentially life-threatening situations very important (Cook & Woods, 1996; Schreiber & Schreiber, 1989). Alarms play an important role in ensuring swift and effective responses from medical and nursing personnel.

Alarms in Critical Care Environments

The problem of how to design effective alarms in critical care environments has been of particular interest for the past decade. Researchers have applied findings from studies in aviation and nuclear power plant environments to critical care (Cook & Woods, 1996). However, anesthesia and critical care environments pose distinct problems. Practitioners are regularly confronted with arrays of technologies that were introduced in a piecemeal fashion and were not necessarily designed to operate in conjunction with one another. Moreover, the most important part of the sensed environment -- the patient -- is not a fixed engineered system but instead has unique physiological characteristics that need to be taken into account when determining what is normal and abnormal. Alarms can reflect the state of the patient (such as unacceptable high heart rate) or the state of the equipment itself (such as loss of signal from electrodes or failure of a breathing circuit), which sometimes may have important consequences.

Researchers in the critical care area have focused on several aspects of the alarm problem: (a) the acoustic properties of alarms, such as audibility, discriminability, and identifiability; (b) the intrinsic meaningfulness of alarms; (c) the use of alarms as sources of information in context; and (d) the organization and management of alarms in context. …

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