Study
During the fall of 2014, the Chemical, Biological, Radiological, Nuclear, and Explosive (CBRNE) unit of the Utah Air and Army National Guard participated in exercises using 2,159 patient encounters that were in PPE (full hazmat and SCBA) also known as level C protective clothing. Temperatures ranged from a minimum of 29°F to a high of 56°F. A mock disaster was practiced for 5 days, and of those 2,159 iterations, 43 were disqualified (2%) for any reason. Two individuals presented with altered mental status and disrupted vital signs and were disqualified for heat injuries with cognitive symptoms (0.00092%). These members were excused from duty, monitored in the medical work/rest tent until mental status and vital signs returned to baseline.
The tool used in the study was the Micro-Mental Test. This is a mental status exam that is more than a simple gestalt of how the patient is performing cognitively but less than a full Mini-Mental State Examination (MMSE). This abbreviated mental status exam provides a field expedient measurement of the individual’s ability to function cognitively. It is important to realize that this exam is most effective when repeated over time to assess the patients’ mental status longitudinally. It would be cavalier to propose that an abbreviated mental status exam would be sufficient to diagnose heat stroke, but a mental status exam—however brief—along with symptoms of hyperpyrexia, abnormal vital signs, and anhydrosis can be a useful tool to make the diagnostic transition from heat exhaustion to heat stroke.
Micro-Mental Status Exam
The traditional mental status measures are appearance, behavior, speech, mood, affect, thought process, thought content, cognition, insight, and judgment. Rapidly assessing mental status is crucial for the assessment of heat injuries, because increased vital signs coupled with neurologic changes indicate a medical emergency. The MMSE is painstaking and a somewhat cumbersome tool to use in the field. Therefore, the authors suggest a micro-mental status exam (Table). This abbreviated mental status exam is performed before the individual is placed in the PPE and enters the working environment.
The individual is then assessed after every rotation exiting the PPE and allowed to rest under supervision. Assessing the individual with vital signs and mental status longitudinally allows the provider to rapidly assess and intervene if the patient begins to exhibit mental status changes along with increased vital signs. The patient is assessed for ataxia, confusion, irritability, and lack of coordination. Patients are asked to find from a file drawer their individual prescreen checklist. This test assesses fine motor skills and cognition. Following this, self-identifying personal information from a precheck sheet is verified, and finally, simple questions regarding orientation to person, place, date, and time are posed.
Assessing Executive Function
Examples of measures of thought processes include assessing executive function by having participants find their paperwork, identifying their platoon leader, and correctly responding to questions, such as, “Where exactly were you working in the emergency area and what exactly were you doing?” This assesses executive function and thought process. Thought content could be assessed with inquiries such as, “Anything troubling about your work?” or “Would you tell me honestly if there were anything troubling or unsafe about the work you have performed?” Cognition could be assessed by questions regarding chain of command (both officer and enlisted), 3 suggestions to improve, 3 suggestions to maintain, and knowledge of the rotation schedule for the rest of the day.
The abbreviated mental status exam should in no way replace the robust and accurate mental status exam. However, in a rapidly changing, austere, or asymmetrical environment, a simple gestalt of the patient is ineffective, and the full mental status evaluation may be too time consuming. The authors propose the Micro-Mental Exam as an alternative. It is imperative that the exam be compared with the baseline assessment of the individual during the prescreening of vital signs before the individual enters the exercise.
This Micro-Mental Exam provides a quick, easy, nonintrusive, and stress-free assessment of the patient. The clarity of cognition and ability to perform simple mental tasks could serve to reassure the provider that the patient has not progressed into the dangerous area of delirium secondary to heat exposure.
Use of this simple tool during the CBRNE exercise resulted in the disqualification of 2 individuals for probable heat injury; additionally, it gave the providers a rapid assessment tool to quickly identify and treat individuals with progressive heat stress to heat stroke.
Discussion
Compared with studies of heat injuries in military and football equipment, the expected heat injury in PPE gear is very low.2-4 The low number of disqualifications during the CBRNE exercise could be due to the extensive measures in place to assist individuals under heat stress. These measures include strict adherence to the work/rest cycles mandated by the DoD, competent leadership in evaluating and treating individuals participating in the exercise, and paying close attention not only to the vital signs, but also participants’ mental status.
