Page 94 - JSOM Spring 2018

Routine Screening Laboratory Studies for
Nonheat Stroke Field Heat Injuries Are Unnecessary

A Retrospective Review

1
Steven G. Schauer, DO, MS ; James A. Pfaff, MD 2

ABSTRACT
Background: Heat injuries are common in the military training Heat stroke is the most serious heat injury and is generally
environment. Base policies often mandate that heat causalities defined as a core body temperature higher than 40°C (104°F)
require evaluation at a higher level of care, which comes at sig- and central nervous system abnormalities such as delirium,
nificant use of resources. Laboratory studies are often ordered seizures, or coma resulting from exposure to environmental
routinely, but their utility is unclear at this time. Methods: This heat (classic heat stroke) or strenuous physical exercise (exer-
project evaluated the use of screening laboratory studies for heat tional heat stroke). Heat stroke can result in multiorgan dys-
8
casualties brought to Bayne-Jones Army Community Hospital, function, including renal, musculoskeletal, cerebrovascular,
Fort Polk, Louisiana. Casualties brought from the field directly cardiovascular, hepatic, and cerebral disorders. Fear of miss-
9
to the emergency department (ED) were included. Abnormali- ing these diagnoses may lead providers evaluating Soldiers to
ties in laboratory study findings, admission/discharge rates, and treat all heat injuries in the same way, regardless of the pre-
length of stay were documented. Results: From May through senting symptoms. This is clearly not practical in an austere
September 2014, 104 casualties were seen in the ED because environment, so patients will often be transported out of the
of heat injury. Laboratory tests were ordered for 101 patients. area of operations to a setting with laboratory and radiologic
Of these, 11 patients were admitted to the hospital because of capabilities.
laboratory, history, and/or physical examination abnormalities.
Nine were discharged in less than 24 hours. The remaining two Transporting Soldiers to the ED from field training operations
were discharged within 48 hours; both had documented altered incurs both significant monetary cost as well as the inherent
mental status on arrival to the ED. Laboratory test abnormali- dangers of transportation. Training in austere environments
ties were seen in most of the patients and appeared to have no can limit the ability of ground transportation and, thus, air
impact on the decision to admit. Conclusion: Routine labora- evacuation (AIREVAC) occurs. The laboratory studies also in-
tory studies appeared to have low clinical utility in this patient cur healthcare costs in a system that is already budget strained.
population. A more targeted approach based on the history and
physical examination may reduce military resource use. The goal of this project was to determine if routine screening
laboratory tests were necessary for all patients who present to
Keywords: heat injury; heat exhaustion; heat stroke; climate; the ED after being diagnosed with a nonheat stroke injury in
rhabdomyolysis; heat the field. To the best of our knowledge, this is the first study
to evaluate the utility of laboratory studies in ED patients with
a heat injury.
Introduction
Methods
Heat-related illnesses and injuries are a spectrum of disease
often separated into categories such as dehydration, heat Design and Setting
cramps, heat syncope, heat exhaustion, and heat stroke. They This was a process improvement project that reviewed data on
1
2
have been reported during military training for centuries. heat injuries in patients transferred from the field to Bayne-
Heat injuries are common in hot environments and result in Jones Army Community Hospital (BJACH) ED. The purpose
Soldiers being removed from training; cumulative exposures of the project was to determine if alternative methods of pro-
increase risk. This affects both Soldier and unit readiness for vider evaluation could safely occur without the need for an
3
military operations. A 2002 report from the Army Medical ED visit. Current base policy mandates that anyone with a
Surveillance Activity noted a heat-injury rate of 3.8 per 1,000 core temperature higher than 39.1°C (102.4°F) must be seen
person-years. The US Air Force reports lower rates of heat in the ED. An Institutional Review Board (IRB) Process Im-
4
injuries, which suggests that different training missions may provement Research Advisory Panel was convened to review
place Soldiers at higher risk than Airmen. Data suggest that the project in advance. The project was determined to meet
5
the heat injury rates among military personnel are not declin- the definition of process improvement; thus, IRB approval was
ing; they possibly may be on the rise. 6,7 not required.
*Address correspondence to steven.g.schauer.mil@mail.mil
1 MAJ Schauer is with the US Army Institute for Surgical Research and the Department of Emergency Medicine, San Antonio Military Medical
Center, Fort Sam Houston, Texas; and the Department of Emergency Medicine, Bayne-Jones Army Community Hospital, Fort Polk, LA. COL
2
(ret) Pfaff is with the Department of Emergency Medicine, San Antonio Military Medical Center, Fort Sam Houston, TX.
88