Volume 6, No. 3 • Fall 1991

“Human Factors” Improve Safety; Anesthesia Applications Sought

Lee 0. Weltner, M.D.

Human factors analysis (sometimes called “ergonomics”) has improved safety and performance in many areas of human endeavor. While medicine, and anesthesiology in particular has benefited from some of this work, a stronger and more direct linkage between anesthesiology and the discipline of “human factors” is needed.

Central questions are: What is the background of human factors? What is its current status? How does human factors relate to anesthesiology?. Why is this connection important? How can we increase the involvement of human factors in anesthesiology? How can this increase safety?


Human factors had its roots in the pursuit of problems with World War 11 military systems and equipment. The formal study of “vigilance” (the watchword of anesthesia care) sprang from interest in the troubles of early radar operators with their monotonous bid critical task. More recently, the Human Factors Society was commissioned to initiate a study of the Three-Mile Island nuclear power plant accident. Similar to comparisons between anesthesia providers and jetliner pilots, analogies have been made to nuclear power operators and their work environment.

Human factors principles developed in other fields can be applied to anesthesiology. Some human factors problems translate more readily than others to similar issues in anesthesiology. The designing of safe and effective manual controls was relevant to the then-existing aircraft cockpit problem of two nearly identical, side-by-side levers: one to control the flaps; the other to retract the landing gear. The lesson learned from the confusing aircraft controls applies to the shape-coding and standardized location of some formerly confusing nitrous-oxide and oxygen control knobs of early anesthesia machines.

Errors During Anesthesia

A recent Anesthesiology Medical Intelligence Article by Weinger and England, “Ergonomic and Human Factors Affecting Anesthetic Vigilance and Monitoring Performance in the Operating Room Environment,” offers many valuable insights. The authors emphasize that human failings underlie most anesthetic morbidity and mortality. They divide the anesthesiologic operating room system into three components. environment, human and equipment. Their article focuses on the first two components, touching on many vital issues such as stress, boredom, sleep deprivation, and task organization. Several constructive suggestions are offered to improve the performance and well-being of anesthesiologists and the safety of their patients. Weinger and Englund have successfully strived to apply wisdom harvested from the human factors literature.

Society Meets

The human factors discipline is continuing to grow and develop. Currently the 5,000-member Human Factors Society reflects diversity in its 17 Technical Interest Groups, including Aerospace Systems; Aging; Communications; Computer System; Consumer Products; Environmental Design; Forensics Professional; Organizational Design and Management; Personality and Individual Differences in Human Performance; Safety; and Training. Newly formed is a Special Interest Group comprised of two distinct components: Medical System and The Functionally Impaired (the latter referring to Rehabilitation Medicine).

The 34th Annual Meeting of the Human Factors Society, held October 8-12, 1990 in Orlando, featured several sessions and presentations of potential interest to anesthesiologist. Many of the topics can be readily generalized to direct relevance in anesthesiology: human performance and mental workload; displays and controls; aircraft cockpit; safety and hazard communication; interface design; expert systems. Others were specifically oriented toward medical systems.

One panel session entitled “Human Factors Engineering Standards, Guidelines, Regulations, and Practices for Medical Products and Devices” focused on the history and current status of the “Human Factors Engineering Guidelines and Preferred Practices for the Design of Medical Devices” published by the Association for the Advancement of Medical Instrumentation (AAMI). The AAMI committee revising these Guidelines met most recently in connection with the ASA Annual Meeting in Las Vegas.

Mr. Sidney Hudspith of Baxter Healthcare described in the Orlando meeting the development of an anesthesia workstation featuring the “Private Eye” a head-mounted visual display of monitor data projected into the edge of the field vision of the operator, similar to the “heads up” display used by some fighter pilots. Hudspith reported that despite favorable trials of their prototype his company has withdrawn from further development of this product.

“Glyph” Proposed

In another session, Dr. Lee Deneault of the University of Pittsburgh departments of Anesthesiology and Information Science, described some advantages of presenting multiple monitored parameters m a single integrated polygon “gyph” visual display as opposed to the typical connection of individual digital and time-varying waveform displays. Even limited familiarity with this new type of visual display in experimental trials permitted anesthesiologists to perform better than with conventional displays.

Dr. Richard Cook, of the Ohio State University’s Department of Industrial Systems and Engineering, presented a fascinating paper in which he and Dr. David Woods, in collaboration with Dr. Michael Howie, of Ohio State’s Department of Anesthesiology, studied the behavior of cardiac anesthesiologist in adapting to the clinical introduction of a new operating room monitoring system. Their description of what is best characters as “dummy automation” highlights the need for greater human factors expertise in the development of such systems.

Dr. Scott Potter, of Ohio State University, presented a critique of a new heated humidifier design which he related to the AAMI human engineering guidelines. He described how the misleadingly simple appearance of the design left users with inaccurate mental models of the device. Simply following the AAMI guidelines would not have avoided the design Haws: that “require professional practice, that is, the application of human engineering principles by experienced practitioners.”

In these sessions, and in other discussions and publications, the human factors community has presented a compelling argument. Many consumer and professional products are flawed by the lack of sufficient human factors expertise in their design. Seemingly, the short-sighted focus of corporate top management on short-term profits has precluded the expense and timely involvement of human factors professionals. Alternatively, some design engineers have incorrectly convinced management that human factors expertise is equivalent to “common sense” which, of course, they certainly possess.

Unfortunately, we (and sometimes our patients) am among the victems of these poor corporate management decisions. There can be no doubt that poorly designed equipment detracts from the safety and efficiency of anesthesia practice. We must do what we can to solve this problem. We must demand equipment that avoids these flaws.

How can we facilitate this important interaction of human factors with anesthesiology. Several avenues come to mind, following existing pathways for the development, dissemination, and application of professional knowledge.

One path for increased interaction is for more anesthesiologist to participate as members d the Human Factors Society, or its Medical Systems … Special Interest Group. Another route is to collaborate with human factors professionals in studies such as those described above.

The vast majority of anesthesiologists are more likely to be reading such articles than to be writing them. The increasing trend for publishing human factors oriented material in the anesthesiology literature deserves encouragement. Though it might not yet warrant formal inclusion in the medical school curriculum, human factors teaching should be definitely incorporated in all anesthesiology residency programs.

Anesthesiologists, clinical engineers, or others responsible for the evaluation and selection of equipment need to be cognizant of human factors issues. Those involved in designing, developing, manufacturing, or marketing medical systems must better utilize human factors knowledge and expertise. Human factors knowledge should be included in the earliest phases of product development.

Those with a spark of interest in this topic and a few hours to spare will enjoy reading the Design of Everyday Things, by Donald A. Norman, ($12.95, Doubleday/Currency). A good overview of human factors science is found in Selected Readings in Human Factors, Michael Venturino, ed., The Human Factors Society, Inc.

Dr. Weltner practices at the Enloe Memorial Hospital, Chico, CA and is a member of the Human Factors Society (P. 0. Box 1369; Santa Monica, CA 90406; (213) 394-1811).