Clinical Communications: Adult
Successful Management of Severe Exertional Heat Stroke with Endovascular Cooling After Failure of Standard Cooling Measures

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Abstract

Background

Exertional heat stroke (EHS) is a potentially life-threatening emergency requiring rapid reduction in core body temperature. Methods of cooling include cold water immersion, ice packs, cold water lavage, and chilled saline, among others. We report a case of EHS successfully cooled using an endovascular cooling device after traditional cooling methods failed to reduce core body temperature.

Case Report

A 24-year old soldier collapsed during a 12-mile foot march while training in southern Georgia. His initial rectal temperature was 43.1°C (109.6°F). External cooling measures (ice sheet application) were initiated on site and Emergency Medical Services were called to transport to the hospital. Paramedics obtained a repeat rectal temperature of 42.4°C (108.4°F). Ice sheet application and chilled saline infusion were continued throughout transport to the Emergency Department (ED). Total prehospital treatment time was 50 min. Upon ED arrival, the patient's rectal temperature was 41.2°C (106.2°F). He was intubated due to a Glasgow Coma Scale score of 4, and endovascular cooling was initiated. Less than 45 minutes later his core body temperature was 37.55°C (99.6°F). He was admitted to the intensive care unit, where his mental status rapidly improved. He was found to have rising liver enzymes, and there was concern for his developing disseminated intravascular coagulation, prompting transfer to a tertiary care center. He was subsequently discharged from the hospital 14 days after his initial injury without any persistent sequelae.

Why Should an Emergency Physician Be Aware of This?

The primary treatment for EHS is rapid reduction of core body temperature. When external cooling methods fail, endovascular cooling can be used to rapidly decrease core body temperature.

Introduction

Exertional heat stroke (EHS) is a life-threatening emergency that requires immediate intervention to rapidly reduce core body temperature to prevent permanent organ damage. Reduction in temperature can be achieved through a variety of methods, including evaporative cooling, ice packs, cold water immersion, cold water lavages, and chilled intravenous (i.v.) fluids. Of these, the most effective method is full-body cold water immersion (CWI) 1, 2. However, CWI presents logistical challenges for an emergency department (ED), including lack of adequate space or drainage, the need for electronic patient monitoring, rapid facilitation of patient entry and exit from the immersion tank, and environmental safety concerns surrounding management of spilled ice and water in proximity to electrical equipment.

Ice sheeting (covering the subject with bed linens that have been soaked in ice water) is routinely used at Fort Benning, Georgia, to approximate CWI with fewer logistical constraints. Ice sheets are often initiated at the point of injury, and the Fort Benning Emergency Medical Services (EMS) protocols provide for continued cooling through the use of skin lavage with ice water slurry and adjunctive use of chilled i.v. saline (3). During the period between April and November 2017, this method was used to successfully reduce the elevated core body temperatures of over 200 patients suffering from moderate to severe heat-related illnesses, including 52 cases of EHS (4). We report a case of EHS that was successfully treated using an endovascular cooling device after prolonged attempts at cooling with ice sheets, ice slurry, and chilled i.v. fluids failed to achieve satisfactory reduction in core body temperature.

Section snippets

Case Report

A previously healthy 24-year old white male Army Ranger participating in the Ranger Assessment and Selection Program (body mass index 27.7) collapsed while performing a 12-mile foot march while carrying a 40-pound backpack. Upon initial evaluation by onsite medical personnel, his rectal temperature was 43.1°C (109.6°F). He was immediately stripped of all gear and clothing and ice sheets were applied. EMS arrived 19 min after the initial application of ice sheets; his repeat rectal temperature

Discussion

EHS is defined as an elevated core temperature, generally > 40°C (104°F), with associated encephalopathy in a patient who has been participating in strenuous exercise (6). These individuals require immediate and rapid cooling and continuous monitoring. Rapid cooling is best accomplished by full body (except the head) immersion in an ice water bath, which produces cooling rates up to 0.35°C/min 1, 7, 8. There have been reports of successfully treating EHS with CWI in the field and at endurance

Why Should an Emergency Physician Be Aware of This?

There are very few case reports detailing the use of endovascular cooling in EHS. In this case, standard cooling methods yielded only a marginal decrease of 1.9°C over a 50-min period. Cold water immersion in the ED was neither available nor would it have been practical in this unstable patient. The implementation of endovascular cooling rapidly lowered the patient's core temperature to normal range within 30 min of initiation and is only the second published use of this application in the

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The views expressed in this manuscript are those of the authors and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the U.S. Government.

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