Risk Management and Medicolegal Aspects of Anesthesia Equipment Use

Risk Associated with Anesthesia Equipment Use

The study of adverse anesthetic events provides insight into their causes and leads to interventions that should decrease their occurrences. Greater attention to improving patient safety and the introduction of new technology is believed to be associated with a declining trend in the overall incidence of anesthesia mishaps associated with the use of anesthesia gas delivery equipment. Nevertheless, adverse outcomes related to equipment failure and/or misuse persist, and the results are often severe. In fact, the inherent rarity of serious complications from anesthesia likely creates an additional hazard. That is, most anesthesiologists do not have the experience or training to respond appropriately to these incidents. Studies of anesthesia practice have yielded valuable data that quantify the frequent causes of errors and have provided insight into the complex environment in which they occur.

Anesthesia is delivered in a complex, dynamic environment that involves the interactions of a surgical insult with unpredictable physiology, numerous pharmacologic interventions, and the use of multiple electromechanical devices. The system involves the interactions of numerous physicians, nurses, and ancillary personnel influenced by a “host of administrative, political, and cultural factors.” In this environment, deviations or “incidents” arise frequently, occurring spontaneously from the patient’s disease (e.g., hypertension), from planned interventions, (e.g., disconnecting the breathing circuit to suction the tracheal tube), or as the result of human error or equipment failure. The majority of these incidents or “near misses” have little or no impact on patient outcome. Events that could or did lead to an undesirable outcome have been termed “critical incidents.” When an event does lead to an undesirable outcome, it is termed an “adverse event.”

The chain of events associated with accident evolution has been studied extensively in other domains in which RM is commonly practiced. Many of the insights gained are equally applicable to the prevention of anesthesia accidents. A well-understood concept introduced into accident understanding and prevention in health care, and anesthesia specifically, is that errors and failures do not stand alone. Rather they are elements embedded within a larger system, in which equipment is only one of several categories of latent risk factors for adverse events ( Table 26.2 ). It is widely accepted that human error must be thought of in this context, i.e., that the operator is rarely the primary “fault.” In fact, the technology is also rarely the sole “fault” or cause of an adverse outcome. The science of patient safety has embraced these ideas, which are critical for establishing measures to avoid adverse outcomes associated with equipment.

Sources

Important sources that serve to define risk associated with the use of anesthetic equipment include national adverse outcome reporting registries such as the online Australia and New Zealand Anaesthetic Incident Reporting System (webAIRS), the United Kingdom’s National Patient Safety Agency adverse events reporting, ^, the French health ministry’s national registry of incidents, and the U.S. Veterans Administration adverse event registry. The American Anesthesia Quality Institute National Anesthesia Clinical Outcomes Registry was initiated in 2010 but has not published compiled data. Other sources, including medicolegal claims databases (the American Society of Anesthesiologists [ASA] Closed Claims Project [CCP]), prospectively collected single institution quality data, ^, retrospective critical incident surveys, ^, and case reports. The primary methodological limitation to prospectively investigate adverse anesthetic equipment events is the rarity of their occurrence; however, organized national registries are beginning to compensate for this challenge. Additional limitations in investigating this topic include heterogeneity in reporting and definitions used to characterize adverse events, and the subjective evaluation of these incidents. The sum of this body of literature forms a representative picture of adverse events related to anesthetic equipment and can help form strategies for their prevention.

National adverse event registries now contain sufficient case samples to provide better insight into the nature and outcomes of anesthesia equipment-related incidents. Some inferences can be made about the prevalence of these rare events relative to other adverse events. However, voluntary reporting still limits understanding of the true incidence. The Australian webAIRS consists of an anonymous online reporting program begun in 2009 which contained 4000 cases as of 2016 with approximately 150 discrete detail elements about each case, ranging from patient demographic information to judgments about causes of anesthetic mishaps. The United Kingdom’s Safe Anaesthesia Liaison Group (SALG) is a working group of the Association of Anaesthetists of Great Britain and Ireland (AAGBI) in partnership with the U.K. National Health Service which has evaluated over 4000 adverse anesthetic events as of 2013. Information queried from reporters includes demographics details, classification of the incident, causation, outcomes, judged causation, and narrative description of the events. The ASA CCP is an evolving database of over 6000 adverse anesthetic events that have occurred over four decades. This database consists of cases provided by numerous malpractice insurers in the United States that are reviewed and evaluated by anesthesiologists. Of these, 115 cases were claims related to anesthesia gas delivery equipment. The U.S. Veterans Health Administration maintains a Root Cause Analysis (RCA) database of adverse medical events that contains details and analysis of 3228 cases from 2012–2015, of which 36 involved anesthetic care.

Incidence

The majority of adverse events in anesthetic practice are multifactorial and involve a combination of systems problems, human factors, and actual technical failures. Isolated anesthetic equipment failures are rare and contribute to the minority of adverse events. Nonetheless, it is valuable for the clinician to understand the incidence of such events and to what degree each is associated with patient injury. Attempts made to identify the incidence of these isolated failures and compare them are limited by varied methodology (e.g., extended timeframe of event collection, definitions used by investigators). Nonetheless, the incidence of adverse events with anesthetic gas delivery equipment has been estimated to occur in 0.23%–0.4% of cases, ^, and represent 1%–12% of reports in adverse anesthetic event databases. ^{, , ,}

The webAIRS database contains 523 equipment-related events in the first 4000 incidents, representing 12% of the reports ( Table 26.3 ). Analysis of adverse events in the ASA CCP database since 1990 revealed that 1.2% (40 of 3369 total claims) were associated specifically with gas delivery equipment. From a practical standpoint, the incidence of equipment failure has been reported in single-institution, consecutive record audits at a rate of 1 in 250 to 1 in 435 general anesthetics. ^,

It is not clear how generalizable these data are to individual anesthetic practices given the range of equipment used, audit reporting compliance, and definitions of “equipment problems.” It is also possible that clinicians may be more likely to report on equipment-related events; hence, those may be overrepresented in databases that include noninjurious events. Fortunately, some of these equipment failures have led to either mandated removal from the market (recall) or improvements in design.

In contrast to isolated equipment failure, “use error,” or what had been referred to in earlier publications as “human error,” had been reported as being responsible for the majority of adverse events and thus represented the most significant contributor to adverse outcomes. Judgment about the contribution of use error remains prevalent in the literature; however, the user and technology are now understood to be intertwined. In addition, there is currently a de-emphasis on personal blame in evaluating adverse events; rather, addressing systems problems has been deemed more fruitful in building a sustainable culture of safe health care delivery.

Characteristics of Adverse Events

As the frequency of anesthesia equipment-related events appears to be decreasing in frequency, it is unclear if the nature of those events or the severity of injuries has changed ( Table 26.4 ). In early reports, the Australian adverse event database defined that the leading sources of equipment problems included unidirectional valves, ventilators, anesthesia machines, breathing circuits, gas supplies, and electricity. More recently, the ASA CCP database includes 14 problems with vaporizers, 11 with supplemental oxygen supplies, 8 with breathing circuits, 5 with ventilators, and 5 with the anesthesia machine itself ( Table 26.5 ). The management of many specific hazards and failures associated with anesthesia equipment is described in Chapter 23 .

Regarding the severity of injury, in events occurring prior to the 1990s, equipment-related claims were more likely to be associated with serious injury or death and larger financial settlements than other anesthetic adverse outcomes. Certainly, the use of financial settlement size is an imperfect surrogate measure of outcome severity, and it is possible that some equipment-related claims were settled preemptively by a manufacturer and were not represented in the ASA CCP database.

Anesthesia gas delivery is complex, with multiple connections and moving parts that would make one likely to suspect that equipment failure would play a prominent role in adverse events. However, even in a simplistic failure model that categorizes attribution to either human or machine, use errors were judged to be more common than equipment failure per se (emphasizing the role of use error in equipment-related critical incidents and adverse outcomes) (see Table 26.5 ). Breathing circuits are an excellent example of this phenomenon. A simple misconnection or disconnection of the breathing circuit was the initiating event in a large proportion of cases. ^{, ,} Importantly when compiled over the entire course of the CCP, this subset of adverse event type remains a large contributor to injury that has not been eliminated by the use of capnography, breathing circuit pressure alarms, and pulse oximetry monitoring.