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Correspondence |
Toronto, Ontario
We are pleased that our article generated interest in the anesthesia community.1 Dr. Lederer identifies several well-known performance shaping factors that induce error. However, most of these are uncontrollable and cannot be eliminated; all health care providers will sometimes be stressed, tired, or emotionally upset. It is irresponsible to design medical systems that do not accommodate these harsh realities. Rather than wishing these factors will simply go away, we should design devices and systems so that providers can function more robustly - even under less than ideal conditions.
Dr. Doyle outlines an excellent taxonomy of patient-controlled analgesia (PCA) hazards to assist manufacturers and investigators improve patient safety. Dr. Lamb correctly reports that well trained, astute nurses play a key role in preventing tragic outcomes from drug errors. Dr. Chan raises questions about the context for our research that we are pleased to address.
Our primary goal is to use human factors engineering design principles to improve the safety of medical devices, not to denigrate any particular manufacturer or model.2 The circumstances surrounding the patient death, not our personal preferences, dictated the particular model we investigated.
That being said, the Abbott Lifecare® 4100 PCA Plus II Infusion Pump is unique in several important respects. First, according to Abbott, by 2000, this device was the market leader, was used around the world, and accounted for about 75% of all PCA use in the U.S., being used in nearly 4,000 hospitals there.3,4 Furthermore, in 2001, ECRI (formerly the Emergency Care Research Institute, www.ecri.org) stated "this pump has a significant safety problem".5 In late 2002, ECRI continued to receive reports of deaths from programming errors with this pump.6 These deaths were not included in our epidemiological analysis.
Second, "the Abbott PCA pumps are the only pumps that ECRI is aware of that can default to a low concentration setting".6 As we explained in our article, this design feature has important safety implications. For example, accepting an initially displayed concentration value of 0.1 mg•mL-1 could lead to an over-infusion of analgesic when a more concentrated drug preparation is used (e.g., 1 mg•mL-1 or 5 mg•mL-1). In contrast, accepting the initially displayed concentration value of 0.0 mg•mL-1, as provided by other PCA pumps described by Dr. Chan, presumably does not lead to any infusion — a fail-safe design feature. In retrospect, given that no study of this type had ever been conducted, analyzing the market leader that has unique design features linked with patient safety seems worthwhile.
We agree with Dr. Chan that human factors analyses of other PCA pumps should be conducted and we encourage him and others to do so. If objective scientific evidence eventually confirms Dr. Chan’s opinion that all PCA pumps are equally error-prone, then the threat to patient safety of PCA use is even greater than anticipated; the total number of deaths from concentration programming errors alone could be greater than our initial upper estimate of 667.1 This would make the application of human factors engineering design principles to protect public health even more urgent.
References
1 Vicente KJ, Kada-Bekhaled K, Hillel G, Cassano A, Orser BA. Programming errors contribute to death from patient-controlled analgesia: case report and estimate of probability. Can J Anesth 2003; 50: 328–32.
2 Lin L, Isla R, Doniz D, Harkness H, Vicente KJ, Doyle DJ. Applying human factors to the design of medical equipment: patient-controlled analgesia. J Clin Monit Comput 1998; 14: 253–63.[Medline]
3 McLeskey CH. Abbott addresses medication errors through advanced PCA technology. APSF Newsletter 2000; 15: 36–7. (www.gasnet.org//societies/apsf/newsletter/2000/fall/07OpinionResponse.htm, May 2, 2003).
4 Abbott Laboratories. LifeCare® PCA Plus II Infuser. (www.abbotthosp.com/PROD/pain/pcaplus.html, August 23, 2001).
5 ECRI. Patient-controlled analgesic infusion pumps. Health Devices 2001; 30: 157–85.[Medline]
6 ECRI. Medication safety: PCA pump programming errors continue to cause fatal overinfusions. Health Devices 2002; 31: 342–7.[Medline]
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