Saturday, June 05, 2010

A Case of Heat Exhaustion

A Case of Heat Exhaustion: A Stitch-in-Time Rescue
by Dr. Chew Keng Sheng and Dr. Abdul Kursi Abdul Latif
Emergency Medicine Department,
School of Medical Sciences,
Universiti Sains Malaysia,
16150 Kubang Kerian, Kelantan, Malaysia


Located near the equator, Malaysia is a tropical country with a constantly hot weather. The town of Kota Bharu, Kelantan, for example has a weather temperature of 23°C minimum and up to 31°C maximum daily (1). Therefore, cases of heat related illnesses are not uncommon. Unfortunately, not many of these cases had been reported in Malaysia and many times, these cases have been overlooked especially those at the milder end of the spectrum of illnesses. Shafie H et al in 2007 reported a case series of nine lucky policemen admitted to the emergency department of Hospital Kuala Lumpur for exertional heat stroke after a special force selection program (2). In this case report, we illustrate yet another fortunate man who was rescued from his heated car before further deterioration occurred to him.

Case Report

A 70 year-old Malay man was admitted to the air-conditioned Resuscitation Zone of the Emergency Department (ED), Hospital Universiti Sains Malaysia after he was found unconscious by the passer-by inside his car parked under the scorching heat of the hot sun.

This man had just come out from his cardiac clinic follow-up visit and continuation of his medications. Unfortunately, as he came out from the clinic, he had trouble looking for his car among the sea of vehicles parked in the open space hospital compound.
After about 15 minutes of walking under the hot sun, he finally found his car. When he got into his car, he felt dizzy. He said that he decided to close his eyes to take a rest. Retrospectively, however, he said that had no recollection of what so ever happened to him since he closed his eyes. In other words, it was not known for how long he was exposed under the heat after he lost consciousness. According to the passerby who brought in the patient, the patient was found unarousable to call and there were stains of vomitus on his pants.

On arrival to the emergency department, he was still drowsy and unresponsive to call. We cleared the secretions in his upper airway by suctioning. His breathing was maintained spontaneously and adequately. However, his core temperature was noted to be 41°C. His blood pressure was 140/80 mmHg, pulse rate was 100 beats/min on admission and capillary blood sugar was 10 mmol/l. He was profusely sweaty.

He was initially treated promptly as a case of heat stroke on the basis of his unresponsiveness and his temperature of 41°C. His clothing was removed and he was immediately given sponging with wet large gauzes placed over his trunk, flexural areas (axillary regions and groin) and tap water sprayed over his entire body including the forehead. Intravenous hydration was started. Over the next 15 minutes, his condition improved. At that point, although he was responding to call, he appeared weak.

About another half an hour later, he became fully conscious and his general condition had also improved. He was subsequently transferred out to the observation ward. His body temperature was reduced to 37.1°C after two hours. Blood investigations (full blood count, blood urea and serum electrolytes as well as serum creatinine and liver function tests) remained within normal range. His creatine kinase level was 230 iu/l. His electrocardiography demonstrated left bundle branch block but there was no dynamic changes. He was subsequently discharged home well after six hours’ stay in the ED with a final diagnosis of heat exhaustion.


This case highlighted the danger of heat related illnesses which are often overlooked. We considered him to be fortunate because he was noticed trapped inside the car by a passer-by early enough to prevent further deterioration in the spectrum of heat-related illnesses. This spectrum can range from minor syndromes such as heat cramps, heat syncope and heat exhaustion to the more severe and life threatening heat stroke (3). More than one year ago, on the 11th April 2006, however, Malaysians were shocked to hear the unfortunate news of a six-year-old girl who similarly was locked inside a van for almost three hours (4). The girl apparently dozed off after being picked up from her kindergarten by a van driver; but unfortunately the driver did not realize that the girl was still inside his van. Subsequently admitted to the intensive care unit in Selayang Hospital, the girl died of heat stroke five days later. One can argue that being a young child probably resulted in her limited physiological responses to heat stress as compared to an adult (5). Nevertheless, old age and those with significant co-morbid illnesses such as diabetes mellitus and those on long term medications such as beta blockers are equally at risk to fail in mounting a sufficient physiological response to cope with heat stress. Beside that, old age is also associated with a low level of expression of heat-shock proteins (6).

Heat-shock proteins are stress proteins expressed by nearly all cells in response to sudden heating during the initial acute-phase response. These heat-shock proteins confer protection to the cells, allowing them to survive, tolerate a second lethal stage of heat stress and to prevent protein denaturation (6). Eventually however, the cells succumb to the deteriorating effect of heat stress. Heat stress causes damage to the organism by at least three mechanisms. Firstly, as mentioned above, heat directly denatures cellular proteins, interrupt cellular enzymatic processes and results in cell swelling as well as apoptosis (3). Temperatures above 41.6°C to 42°C are considered to be the critical thermal maximum for humans to tolerate for 45 minutes to eight hours (3,6). Extreme temperatures above 49°C may result in near immediate cell death in less than five minutes (3,6). The patient highlighted in this report had an admission core temperature of 41°C. Therefore, we consider him fortunate to be rescued out in the nick of time! Secondly, heat stress ultimately results in an exaggerated response with increased expression of cytokines such as tumor necrosis factor-α, interferon γ and interleukin-6 (3,6). Such exaggerated response may result hypoperfusion in certain areas especially in the splanchnic bed. This result in endotoxinemia and the production of highly reactive oxygen and nitrogen species that further contribute to thermoregulatory failure and shock. Thirdly, heat stress results in vascular endothelial injury, increased vascular permeability, activation of the coagulation cascade and disseminated intravascular coagulation.

The distinction between heat exhaustion and heat stroke is not always clear cut although heat stroke differs from heat exhaustion in three clinical aspects (3,5,6). Firstly, heat stroke usually has a core temperature of greater than 40.6°C and heat exhaustion usually has a core temperature of 40°C or less. Secondly, heat stroke results in central nervous dysfunction as evident by delirium, convulsion and coma. Thirdly, heat stroke usually has anhidrosis on the basis of thermoregulatory failure. Nevertheless, we consider such differentiation arbitrary and mechanical (7). Cases that fall in between like the patient in this report might be difficult to differentiate (3).

However, in terms of patient management especially first aid and emergent management in the emergency department, the principles are almost similar. The distinction between heat stroke and heat exhaustion, therefore, is important only in terms of prognostication as well as how expeditious cooling should be done. But bearing in mind, strict adherence to the criteria of theoretical definition may result in a delay of practical management (3,8). Failure to treat heat exhaustion adequately can results in the deterioration to heat stroke (3,7) and in fact, heat exhaustion may be a warning sign of impending heat stroke (5). Therefore, if there is uncertainty in the differentiation between heat exhaustion and heat stroke, the patient should be treated aggressively and promptly as heat stroke, especially if the patient’s mental status is questionable (3).

In terms of first aid management, at any cost, there should be no delay in removing the patient from the hot environment (3,5). Morbidity and mortality is directly associated with the duration of elevated core temperature as well as how rapidly the core temperature is reduced (3). In this aspect, we are grateful to the passer-by for removing him out from his car. Again, we consider him very fortunate not to have locked himself in the car from the inside. A non-ventilated car in a hot environment may reach a temperature of up to 54°C to 60°C in less than 10 minutes (9).

Cooling should be instituted immediately. We implemented evaporative cooling technique rather than ice water immersion. These two methods are the most widely accepted methods of rapid cooling (3,10). Controversy exists and persists over which method is more effective (3). In a review article by Harker and Gibson (10), they commented that there is a geographical perspective and preference in terms of which method to be used. An evaporative cooling technique is preferred in the Middle East and South Africa whereas clinicians in the United States are divided in their preference (10). Just as the evaporative cooling technique is used in cases during the annual Mecca pilgrimage, we believe that evaporative cooling technique is more acceptable in our Malaysian population. Ice water immersion would reduce the core temperature rapidly but it would be extremely uncomfortable especially if the patient is still conscious. We applied plenty of wet gauze over the flexural area of the body as well as copious spraying of tap water over his entire body. The cooling should reduce the temperature to 38.5°C to 39°C. Over cooling is not advisable.

Intravenous hydration should be given for patients who cannot tolerate orally and urinary catheter as well serum electrolytes and hematocrit should be monitored to ensure adequate hydration. Antipyretics have not been shown to be useful (3).


In conclusion, it is imperative that we recognise that heat-related illness are not uncommon given the fact that the weather in Malaysia is constantly hot with a humidity of up to 70 – 80% daily (1). Above the humidity of 35%, convection alone does not adequately dissipate heat from the body (7). As such, public education is very important. The public has to be educated regarding the need to take “heat break”, away from the hot environment and getting into air-conditioned areas from time to time. Heat breaks in an air-conditioned area for a short period of 2 hours a day can decrease the rate of heat stroke (7). Drinking plenty of water during hot weather is important. Dehydration of as little as one percent can impair heat dissipation (7). Parents need to be educated too regarding the child safety of not leaving their children unattended inside the car under hot environment. And as illustrated in this case, healthcare professionals need to be reminded that delineating heat stroke from heat exhaustion is not always as clear cut as stated in textbooks. In cases of uncertainty, the patient should be treated as heat stroke. Finally, as Malaysia is fast becoming a developed nation with an increasing popularity in outdoor sports activities, especially in motor sports such as the Formula 1 Race, the MotoGP Race, the Japan GT Race as well as reality shows and extreme sport and adventurous challenges, clinicians need to be aware that we may be seeing an increasing number of heat-related illness in Malaysia.


1. Weather Forecast For Major Towns/Tourist Destinations on 8 December 2007. In: Malaysian Meteorological Department (MMD). Available at Accessed on 8 December 2007

2. Shafie H, Abd Wahab M, Masilamany M, Abu Hassan AA. Exertional Heat Stroke: A lucky bunch of overly motivated policemen! Hong Kong J. Emerg. Med. 2007;14:37-44.

3. Lugo-Amador NM, Rothenhaus T, Moyer P. Heat-related illness. Emerg Med Clin North Am 2004;22:315-27, viii.

4. Jessy KS. Girl Locked In Van Dies. In: The Star Online 11 April 2006. Accessed 11 April 2006. URL:

5. Grubenhoff JA, du Ford K, Roosevelt GE. Heat-Related Illness. Clinical Pediatric Emergency Medicine 2007;8:59-64.

6. Bouchama A, Knochel JP. Heat stroke. N Engl J Med 2002;346:1978-88.

7. Walker JS, Hogan DE. Heat Emergencies. In: Tintinalli JE, Kelen GD, Stapcznski JS, eds. Emergency Medicine: A Comprehensive Study Guide. 6th ed: McGraw-Hill, 2004.

8. Kosla R, Guntupalli KK. Environmental emergencies: Heat-related illnesses. Critical Care Clin 1999;15:251-63.

9. Centers for Disease Control. Injuries and deaths among children left unattended in or around motor vehicles - United States, July 2000 – June 2001. MMWR 2002;51:570.

10. Harker J, Gibson P. Heat-stroke: a review of rapid cooling techniques. Intensive and Critical Care Nursing 1995;11:198-202.

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