Situation Awareness in Anesthesia: Concept and Research

Abstract

SITUATION awareness (SA) is defined as “the perception of elements of the environment within a volume of time and space, the comprehension of their meaning and the projection of their status in the near future.”1It describes the ability of an individual to maintain an adequate internal representation of the status of the environment in complex and dynamic domains where time constants are short and conditions may change within seconds and minutes. The concept was first used in the field of military and commercial aviation and described in detail for the first time in the late 1980s by Endsley.1According to the definition, SA is subdivided into three hierarchical levels: perception (SA level I), comprehension (SA level II), and projection (SA level III).2In 1995, the concept of SA was introduced into the field of anesthesia by Gaba et al. 3Later, SA was classified as an important nontechnical skill4and was embedded in the Anaesthetists’ Non-Technical Skills (ANTS) taxonomy and behavior rating tool. This framework was designed especially for anesthetists and identified four main nontechnical skills: situation awareness, decision-making, teamwork, and task management.5In this review, the concept of SA is presented, and its importance for accurate decision-making and performance is illustrated. Insights into different approaches for the assessment of SA are provided and skills that are related to high levels of SA are described. Starting from a cognitive theoretical background, we identify types of error that may occur during the development of SA. Furthermore, implemented SA training strategies from other domains are described and discussed with respect to their applicability in anesthesia. Finally, we briefly present strategies to improve the design of patient monitors with respect to SA during daily anesthesia practice.The term SA has been used with respect to individuals, teams,1and systems.6To illustrate these different approaches, a critical incident is presented:A 68-yr-old man presented with an acute abdominal crisis and clinical signs of sepsis. General anesthesia was induced by a fourth-year anesthesia resident for exploratory laparotomy. After uneventful induction of anesthesia, a catheter was placed in the radial artery for blood pressure monitoring. An internal jugular catheter had been placed 2 days earlier. Thirty-five minutes after the start of surgery, a gastrointestinal perforation was identified as the underlying cause for peritonitis. At this point, the patient had a systolic arterial blood pressure of 95 mmHg and a heart rate of 105 beats/min despite administration of low doses of noradrenaline and 1,000 ml of crystalloids. The surgeons mentioned a diffuse bleeding tendency, and the resident started to administer fresh frozen plasma. Two minutes after starting the fresh frozen plasma, he noticed that the blood pressure had decreased substantially and that the heart rate had increased further. He looked at the surgical field and asked the surgeons whether there was any acute and uncontrolled severe bleeding. The surgeons answered in the negative. In the belief that an acute bacteremia was compromising hemodynamic stability, the resident increased the doses of noradrenaline. However, the systolic blood pressure remained low at 60 mmHg, even at a dose of 2 µg kg-1min-1of noradrenaline. At this point, he called for the senior attending anesthetist. At the same time, he noticed that the electrocardiogram ST segment was becoming progressively more depressed. He increased the fraction of inspired oxygen to 1.0. The resident informed the surgeons about the severe problems in maintaining blood pressure and about relevant changes in the electrocardiogram. He also indicated that a myocardial infarction could be the cause of this constellation and advised the surgeons to be prepared to perform chest compressions. A nurse was requested to prepare adrenaline for both bolus injections and continuous administration. Some minutes later, the senior anesthetist entered the operating room and, after a short phase of orientation, advised the resident to administer adrenaline. At the moment of injecting adrenaline into the central venous line, the resident noticed severe urticaria in the skin in the vicinity of the central venous line. He immediately communicated this finding to the senior attending anesthetist, and the diagnosis of anaphylactic shock caused by fresh frozen plasma was made. After administration of histamine blockers and glucocorticoids, the remainder of the surgical procedure was uneventful and the patient recovered without any neurologic deficits.SA level I (perception of the patient’s state) was formed in the aforementioned case by collecting relevant information from monitoring the patient’s vital parameters (low blood pressure, heart rate, oxygen saturation, electrocardiogram), the surgical field (no bleeding), and the appearance of the patient (urticaria). Additional information was acquired