Situation Awareness in Anesthesia

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 through communication with the team (bleeding tendency, intestinal perforation, no acute severe bleeding).A patient’s condition is often static or changes very slowly during the maintenance phase of uneventful anesthesia. However, during induction and emergence from anesthesia or during a critical incident, they may change substantially in a very dynamic manner. The appropriate distribution of attention during such events determines the sensory input to the anesthetist and is therefore an important underlying process of SA level I.7–9In terms of the critical incident described above, a failure of attention would have occurred if the anesthetist had not noted the urticaria (SA level I) during the administration of adrenaline via the central venous catheter, even though this sign had been within his perceptual field. Such failures occur because of attention being directed at other information that appears more relevant.SA level II encompasses the anesthetist’s comprehension and understanding of these variables. Accordingly, anesthetists integrate SA level I knowledge with their long-term memory about medical knowledge, medical guidelines, mental models of physiology and pharmacology, and alterations of the physiologic state by specific surgical procedures. With good level II SA, the anesthetists would recognize that anaphylactic shock is the cause of the low blood pressure and urticaria. Together with the senior anesthetist, the correct diagnosis was made based on the patient’s state and the underlying data. Thus, SA is more than perceiving data, it is integrating those data to understand what they mean and what is pertinent for the current situation.SA level III is the highest level of SA and is the level at which anesthetists will project the expected future development of the patient’s status, which is crucial for early and adequate proactive management of resources to meet the goals of therapy. In the Case Example, administering fresh frozen plasma to address a bleeding tendency and advising the surgeons to be prepared for chest compressions are examples of decisions and communication that emerge from SA level III.In conclusion, the anesthetist’s ability to actively direct their attention toward the main sources of information and to correctly understand and interpret the information they have at hand, enabling them to anticipate the future development of the case, plays a substantial role in treating critical incidents effectively.1,4,9,10SA is considered indispensable for subsequent decision-making, teamwork, and task management3,5,8and is therefore crucial for patient safety.Anesthetists are of an team of in the project of the SA concept where the of is the cognitive process within the anesthetist’s has been The is to and to what SA is present a team and to the that are used to SA within and SA is defined as “the to which team the SA for his or this it is not that a team has a of it is that be of that are relevant to their and However, not the information to be with would be cognitive if SA was the team performance that SA is for those of the information that are relevant to team SA is therefore defined as “the to which team have the same SA on SA a team decisions be based on information from team This for an of a of performance would occur team are not to anticipate which is by the to and team SA is by the SA which be defined for the SA and a of information and to a and and of information the SA as mental models the and SA and other and environment into in team SA both for that are as in an operating or for in time or such as with a change or in a where team may be and team to the critical incident described in the of this the information about the urticaria was with the attending anesthetist not with the they may have this with the of team SA. was also and of information whether there was acute severe bleeding. 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The ability to SA and with the anesthetist’s skills for this process are acquired with and A is that it is to more and these skills and performance by training that is designed to improve specific SA the development of SA training it is a to first identify that may individual and team SA in both and clinical that such training be on the role of SA in both in and in that direct and of SA and performance are to this design of for information in SA and field of In this review, we briefly on the design of patient monitors and discussed that increased performance because of the development of SA be a are from other domains that information on level II SA and level III SA, both and anesthesia, data could be embedded in for to a more of information and in of the anesthetist’s may of information that SA at levels by integrating the data physiologic would be a that the patient’s state to a and comprehension and conclusion, SA has to be as a critical of decision-making that has a direct on performance in medical A of skills and that SA have been described that are based on from a of are and to anesthesia, that are important for SA in this have not been Thus, there is an and a for more in the in terms of individual SA and in terms of team SA. of decisions are based the development and of into the on SA. Finally, training approaches from other domains designed to improve SA be to the in anesthesia to more improve this important in