Situation awareness (SA) can be 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’.1 In simple terms, it is knowing what is going on around you by extracting information from the environment and then integrating that information to create a notion of the situation and anticipate future events. Therefore, SA is important for effective decision-making, performance and teamwork.2 Understanding the meaning of SA and how to improve it in a complex work environment, such as the operating room (OR), is essential for patient safety.
According to the definition, SA is subdivided into three levels: perception (level I), comprehension (level II) and projection (level III).2 The first level comprises the identification of the key elements that assess the ongoing situation; in the OR, the perception of the patient’s state is provided by the patient (for example, through verbal communication or appearance), monitors, patient charts, communication within the team, anaesthesia machines, respirators, and the surgical field.3 The second level comprises the comprehension and integration of multiple pieces of information and the determination of their relevance to the situation to form a coherent mental picture. Finally, the highest level entails the ability to forecast the future development of the patient’s state and determine the best way to proceed.
Generating SA and maintaining it at a high level can reduce the probability of patient injury, because the healthcare provider can respond more quickly to an emerging problem and it can allow proactive management of human and material resources during a crisis.3,4
Team SA (TSA)
TSA is ‘the degree to which every team member possesses the SA required for his or her responsibilities’.5 Teamwork is characteristic to the OR, where an interdisciplinary team of individuals is engaged in the common project of ‘patient treatment’.2 In a highly effective team approach, decisions should be based on information derived from all team members. This allows for an efficient plan of action; otherwise, a breakdown of performance would occur when team members are not able to anticipate what help is needed by the others.6,7 However, not all members of the team should be aware of the same thing at the same time and nor does all the information need to be shared with every individual involved.
Rather, it is necessary that each person be aware of circumstances that are relevant to their respective roles and responsibilities and to create a system where the right information reaches the right person at the right time, and this involves team coordination.3,8,9 Team processes and behaviours that can improve TSA include closed-loop communication, group prioritisation, contingency planning and actively sharing SA about the patient, planned procedure and potential critical events.6,10
Distributed SA (DSA)
DSA is a concept that recognises the contribution of technical systems. The entire system including human and non-human subsystems, and the interactions between them, is considered to develop SA. Hence, cognitive processes occur at a system level rather than an individual level.11 The DSA approach allows a better overall understanding of the operating theatre interactions where a group of people (anaesthetist, surgeon, nurse, patient) interact with external objects (for example, equipment, monitors, charts) in a dynamic explicit and implicit way, and it is only when the interactions between all the individual components are compiled that a coherent picture emerges.12
There can be failures at each level of SA, leading to low performance.13 In the first level (perception), relevant information may not be correctly detected or if too much data are perceived at a time, we become overloaded, focusing on just part of the information (‘tunnel vision’) and missing parts that matter. It is widely recognised that more data does not equal more information. Today’s systems’ problems are not the lack of information but finding what is needed when it is needed; therefore, a critical part of SA level I is learning the cues to watch for (proper distribution of attention).2
An outside view sometimes helps to reveal what we cannot see or give additional information that might help highlight that something has been missed. In the second level (comprehension), the situation might not be understood correctly, despite all the relevant information being detected. This is due to an inappropriate or absent mental model; with time pressure and high cognitive workload we may get drawn into bias by selecting a mental model that we prefer based on our experience.3 In the third level (projection), the future is not correctly anticipated, although the situation is understood. As errors on SA levels II and III necessarily involve long-term memory content for the processing of basic data, this may be due to a lack of training and experience.3,4
Schulz et al reviewed 200 reports from the German anaesthesia critical incident reporting system and found that SA errors were involved in 81.5% of the cases; in addition, more errors on the levels of perception (38%) and comprehension (31.5%) were identified.4 With a similar methodology, we reviewed 100 incidents reported to the Spanish anaesthesia and intensive care incident reporting system (SENSAR; Safety Reporting System in Anaesthesia and Rescuscitation) and found comparable results.
SA errors were identified in 65% of the cases and the majority were on the levels of perception (51%) and comprehension (8%).
The role of expertise and training
Important cognitive mechanisms for the development of SA as well as knowledge bases and task skills are gained with experience. Many studies have shown that experienced subjects develop SA in a shorter time and with less effort than novices. These differences may be attributable to several factors that determine the achievement of good SA, such as correct distribution of attention, prioritising information, dynamic switching between goal-driven processing and data-driven processing, automaticity, which can provide good performance with very low level of attention demand, learned skills, pattern-matching with prototypical situations, and development of mental models that help in the integration of information and projection of future states.2
Patient simulation and related debriefing techniques can enhance individual and team performance by focusing on skills and behaviours related to good SA, such as prioritisation, and coordination and communication that are essential for the effective treatment of critical incidents.3–10
Assessment of SA
Several direct and indirect methods have been developed to assess SA and can be summarised as query-, rating- and performance-based techniques. In query techniques, the subjects are asked directly about their perception of certain aspects of the situation. The Situation Awareness Global Assessment Technique (SAGAT) has been validated as an objective and direct method to evaluate different levels of SA during a simulated scenario, and consists of stopping at random points to ask the participants to complete a questionnaire regarding what is occurring at that specific time. This technique can be perceived as intrusive due to freezes in a simulation but many studies have shown it does not affect performance.3,14
In rating techniques, the subjects or observers are asked to rate SA directly along a few dimensions (SA Rating Technique) or indirectly through behavioural markers of SA (for example Anaesthetists’ Non-Technical Skills scale, Ottawa Global Rating Scale). The SA Rating Technique is less intrusive but was found to have no correlation with measured SA using SAGAT.3,15 Rating techniques using behavioural markers are applicable in clinical settings but they are intended to assess non-technical skills in general and are not designed to specifically assess SA.3 Performance-based techniques evaluate the global performance associated with a measure (for example, simulated patient outcome); however, they do not inform directly about SA. More recently, eye tracking devices have been used to evaluate SA during simulated critical incidents, hypothesising that the distribution of visual attention can be correlated with individual SA, but this remains unclear.16
In the OR, the anaesthetist monitors up to 32 real-time variables while performing many other tasks (for example, intubation, administration of anaesthetic gases and drugs, insertion of intravascular catheters, communication with the surgeon etc). This large workload can lead to deficits in performance. Failures in detecting changes in the patient’s situation can lead to critical incidents; therefore, effective information display is essential.
Patient monitors provide relevant information required for establishing accurate SA,3 and improving the design of the displays in a way that facilitates the extraction of time-critical events can avoid harmful patient outcomes.17 In traditional displays, single pieces of information, each derived from a single sensor, are presented; the anaesthetist then must then integrate all this information to obtain an accurate picture of the patient’s state. This is time consuming and involves a high cognitive demand.
Therefore, a recent and growing field of study concerning the improvement of monitor displays has been developed. The use of graphical objects, that integrate different variables and facilitate rapid visual perception of the patient’s situation, have the potential to improve clinical performance by reducing detection times for critical events and increasing the anaesthetist’s SA.17,18
The OR is a complex and critical environment where conditions may change in a short period of time. The knowledge and improvement of SA can increase the performance in this domain and, therefore, provide better patient outcomes.
To accomplish this common goal, all members of the surgical team must perform their roles with full understanding of the situation. Training and experience can provide the skills and behaviours that influence the achievement of good SA. It is widely recognised that critical event management in patient simulators is a potentially beneficial tool: however, there are still no sufficient methods to objectively determine its effectiveness. SA can also be improved through effective data presentation and, so far, several promising studies on OR displays have been presented but further research is needed.
1 Endsley MR. Design and evaluation for situation awareness enhancement. In: Proceedings of the Human Factors and Ergonomics Society 32nd Annual Meeting 1988:97–101.
2 Endsley MR. Theoretical underpinnings of situation awareness: A critical review. In: Endsley MR, Garland DJ (eds) Situation Awareness: Analysis and Measurement. Lawrence Erlbaum, Mahwah NJ; 2000:3–32.
3 Schulz CM et al. Situation awareness in anesthesia: concept and research. Anaesthesiology 2013;118(3):729–42.
4 Schulz CM et al. Situation awareness errors in anaesthesia and critical care in 200 cases of a critical incident reporting system. BMC Anesthesiol 2015;16(4)
5 Endsley MR. Towards a theory of situation awareness in dynamic systems. Hum Factors 1995;37:32–64.
6 Endsley MR, Jones WM. A model of inter- and intrateam situation awareness: Implications for design, training and measurement. In: McNeese M, Salas E, Endsley MR (eds) New Trends in Cooperative Activities: Understanding System Dynamics in Complex Environments. Proc Hum Fact Ergonomics Soc 2001:46–67.
7 Xiao Y, Mackenzie CF, Patey R. Team coordination and breakdowns in a real-life stressful environment. In Proceedings of the Human Factors and Ergonomics Society 42nd Annual Meeting, Chicago, October 5–9, 1998:186–90.
8 Garbis C, Artman H. Team situation awareness as communicative practices. In: Banbury S, Tremblay S, (eds). A Cognitive Approach to Situation Awareness: Theory and Application. Ashgate Publishing Company, Burlington, USA;2004:275–96.
9 Harris KT et al. Improving patient safety with team coordination: challenges and strategies of implementation. J Obstet Gynecol Neonatal Nurs 2006;35(4):557–66.
10 Haynes AB et al. Safe Surgery Saves Lives Study Group: A surgical safety checklist to reduce morbidity and mortality in a global population. N Engl J Med 2009;360:491–9.
11 Stanton NA et al. Distributed situation awareness in dynamic systems: Theoretical development and application of an ergonomics methodology. Ergonomics 2006;49:1288–311.
12 Fioratou E et al. Beyond monitoring: Distributed situation awareness in anaesthesia. Br J Anaesth 2010;105:83–90.
13 Wright M, Endsley M. Building shared situation awareness in healthcare settings. In: Nemeth CP (ed) Improving Healthcare Team Communication. Ashgate Publishing Limited, Hampshire: 97–115.
14 Endsley MR. Direct measurement of situation awareness: Validity and use of SAGAT. In: Endsley MR, Garland DJ (eds) Situation Awareness: Analysis and Measurement. Lawrence Erlbaum, Mahwah NJ; 2000:147–74.
15 Endsley MR et al. A comparative evaluation of SAGAT and SART for evaluations of situation awareness. In: Proceedings of the Human Factors and Ergonomics Society 42nd Annual Meeting, Chicago 1988:82–6
16 Schulz CM et al. The influence of anaesthetists’ experience on workload, performance and visual attention during simulated critical incidents. J Clin Monit Comput 2014;28(5):475–80.
17 Zhang Y et al. Effects of integrated graphical displays on situation awareness in anaesthesiology. Cognition Tech Work 2002;4: 82–90.
18 Drews FA, Westenskow DR. The right picture is worth a thousand numbers: data displays in anesthesia. Hum Factors 2006;48(1):59–71.