Introduction
Heat stress affects surgeons whereby heat is trapped under impervious protective surgical gowns increasing the body temperature,1altering thermal comfort,2and possibly contributing to distractions in cognitive performance which may increase rates of surgical errors.3 Literature does not exist reporting body temperatures of surgeons, their perceptions of comfort/discomfort, and measures of cognitive performance in real-time operating conditions, and whether surgeons experience a degree of heat stress sufficient to impair their cognitive performance. However, experiments in simulated surgical settings studying heat stress,3-5revealed increased thermal discomfort perceived by surgeons and reduced cognitive performance.4 Warm standardized ambient temperature limits in operating rooms, 20-23ºC (68º-73.4ºF) were established to protect vulnerable sedated patients from hypothermia6 and may add to the thermal discomfort surgeon’s experience.
Background
Complex systemic and cellular processes occur as body temperature rises. Most individuals initially acclimate to acute circulatory system responses, central nervous system (CNS) activation and molecular responses to maintain homeostasis, a balanced state within body systems.7 Chronic exposure and prolonged contact to heat stress eventually predispose some individuals to develop adverse physiological changes including: impaired immune response, suppressed digestion, anxiety, depression, heart disease, weight gain, neurotoxicity, and chronic kidney disease of unknown etiology.8-12The effects of elevated and prolonged activation of the CNS may leave the hippocampus region of the brain vulnerable to potential injury, neurotoxicity or metabolic changes8 potentially resulting in alterations in cognitive performance.13
Cognitive performance is a function of the brain that allows individuals to use acquired knowledge to work through mental processes and exposure to stress.4 Several heat stress studies performed in industry and simulated climatic heat chambers, measuring reaction time, short-term or working memory, and executive function or decision-making of participants, reported an increased number of errors and impairment of cognitive performance appearing within 20 to 30 minutes.13-16
Physiological and psychological responses to heat stress are experienced by all members of surgical teams, although the focus of this review of literature only addresses the surgeon’s response to heat stress as the chief team member making clinical decisions.
Purpose
The purposes of this integrative review is to describe an association between heat stress and cognitive performance of surgeons in occupational surgical settings and to explore topics that influence this association. The objectives of this review of literature are to: 1) review and assess quality of published reports pertaining to occupational heat stress and cognitive performance; 2) identify gaps in the evidence base regarding surgeon’s physiological and psychological responses to elevated temperatures while performing surgery; and 3) to determine if an association between heat stress and cognitive performance of surgeons' in surgical settings exists.
Method
A comprehensive discursive search was conducted in PubMed, CINAHL, and Medline databases (January 2000 to present), as well as, social networking for literature advise with expert research scientists in the field of heat stress through ResearchGate. A review of literature was completed using the framework of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses.18 A total of 61 publications were reviewed, eight publications (4 experimental studies, 3 descriptive studies, and 1 review article) were selected according to physiological responses to heat stress or cognitive performance concepts in relation to heat stress.
Strategies for identification, retrieval, management, and inclusion decisions of primary studies to determine rigor, credibility, and relevance19were considered using the following criteria; 1) empirical assessments describing a relationship between thermal comfort/discomfort and physiological responses to heat stress in the surgical setting or similar environment where individuals were impacted by heat stress, 2) empirical and theoretical perspectives describing a relationship between heat stress and psychological responses impacting cognitive function, performance, or perceptions in the surgical setting or similar environments where individuals were impacted by heat stress. The relevance of integrating heat stress and cognitive performance of surgeons while performing surgery has application to develop future research and establish interventions and guidelines to improve current practice.19
Results
The synthesis of literature describing the physiology of heat stress defines this phenomenon as a physiological process that involves increased resilience to heat exposure when heat exchange between the body and environment is compromised. This process results in thermal discomfort which leads to thermal stress and an acute physiological response is initiated to achieve homeostasis and promote acclimation to elevated temperatures.3,4,20The influence heat stress has on cognitive function is collectively define as the mental ability to identify when a significant change in a process is occurring, requiring focus and attention in the decision making methods.4,13-16Executive function, attention, short-term memory, processing speed, reaction time, and combined tasks are repeatedly referenced throughout the review as areas of cognition that are impaired, impacted, and difficult to perform while physically responding to heat stress.4,13-16The impact heat stress has on surgeon’s operative performance and cognitive function needs the utmost attention based on patient vulnerability and potential risks to surgical performance.3
Discussion
Synthesis of literature has highlighted a new understanding of physiological and psychological dangers experienced by surgeons wearing impervious sterile gowns and protective equipment for long arduous hours. Gaps in literature indicate true experiments are still needed in many areas because no data could be found identifying the presence or absence or severity of heat stress experienced by surgeon’s heat accumulation, degree of discomfort, and whether cognitive distraction is a sequela or how long heat stress needs to exist to impact cognitive performance, thus descriptive studies of surgeons as sources of heat stress need to be conducted. The relationship between heat stress and cognitive performance of surgeons have suggested the use of interventions such as cooling vests and physiological strain index measurements to monitor heat stress in the surgical setting. In short, we know that heat stress has an effect on surgical performance because of basic human responses to heat, but we need to know to what extent and what solutions are to address the issue. The synthesis of literature presents the current state of science, contributes to the development of nursing theory of heat stress management, and will eventually have application to practice and policy development.17