Correspondence

Treatment of exertional heat injuries with portable body cooling unit in a mass endurance event

To the Editor,

Exertional heat illness (EHI) occurs mainly in active individuals pushed to their physical limits, resulting in overheating from generation of heat faster than what the body can dissipate [1]. The resultant dysfunction at cellular and organ level leads to a spectrum of diseases from minor heat cramps through heat exhaustion to life-threatening heatstroke [2]. In mass endurance events, runners with heat illnesses are typically treated with ice packs or cooled with ice water in the prehospital setting [3], before the more definitive methods of cooling by immersion in ice water [4] or body cooling units (BCUs) [5] in the hospitals. We report the use of a field-deployed BCU in cooling hyperthermic patients from a Half marathon (21-km run).

Seventy-two thousand runners participated in the event, which was held in an ambient temperature of 30?C with

relative humidity of 85%. The median age of participants was 25 years (range, 18-45 years old), and 72% of the runners were male. The diagnostic criteria for heatstroke included (a) a rectal temperature greater than 40?C and (b) marked alteration in neurologic function such as delirium, coma, or convulsions [6]. Casualties with (a) a rectal temperature greater than 38.5?C, (b) mild alterations in neurologic function such as giddiness, and irritability were treated as for heat exhaustion [7].

After the diagnosis of heatstroke or heat exhaustion, Initial resuscitation was commenced immediately, and the patients were transferred to the BCU. The BCU is installed within a portable 20-ft container (Fig. 1). There are 2 beds within the container to treat 2 heat casualties simultaneously (Fig. 2). The 22 nozzles over each bed can generate mist of 22 um at a rate of 0.5 L per hour per nozzle. The atomized water is blown over the patient’s entire body at Room temperature (between 28?C and 34?C) and at a rate of 0.5 per milliseconds. This method of evaporative cooling had been demonstrated to be effective in the treatment of heat injuries [8]. The use of water at room temperature, as opposed to cold

Fig. 1 The exterior of the portable Body Cooling Unit when deployed.

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Correspondence

Fig. 2 The 2 trolleys inside the BCU allow two patients to be treated simultaneously.

water, had a physiologic advantage because it minimized the cold-induced vasoconstriction and heat-producing shivering that would reduce the efficacy of the cooling measures [9]. The cooling therapy would be terminated once the rectal temperature falls below 39?C to avoid hypothermia [10]. Casualties would subsequently be transferred to a tertiary care center for further management.

There were 7 hyperthermic patients, and 3 patients with heatstroke were hypotensive on arrival (Table 1). Patient 1 was intubated within the BCU, started on intravenous fluid resuscitation, and cooled in the portable BCU. He responded well to resuscitation, with a restoration of blood pressure to 110/51 mm Hg and lowering of rectal temperature to 39.0?C.

In the hospital, the laboratory investigations (Table 2) demonstrated elevated levels of the creatine kinase (CK), CK- MB, and troponin T in all the patients. Patient 1 required management in the intensive care unit and developed disseminated intravascular coagulation, hepatitis, rhabdo- myolysis, and acute renal failure. He eventually made a Full recovery with no neurologic sequelae or end-organ damage and was discharged well after 10 days of hospitalization. The remaining patients were treated with intravenous hydration and discharged well after an average of 3 days of hospitalization (range, 3-5 days).

Table 1 Clinical parameters of runners with EHI

Patient Age/sex Diagnosis Initial T_rect after Time Cooling Initial parameters

Parameters after resuscitation

T_rect (?C) cooling

(?C)

taken rate (min) (?C/min)

BP (mm Hg) PR (beats/min) BP (mm Hg) PR (beats/min)

247

Heat injury is common during strenuous activities in hot climates, and the incidence of heat injury ranges from 13 to

14 per 10 000 individuals per day [11,12]. Heatstroke accounted for 2% of the sudden deaths in young competitive athletes [13], and the intensive care unit mortality was reported to be 64% [14].

The BCU used to be a bulky apparatus that was located within a treatment center [8] and would not be adequately responsive to treat heat casualties on site. In this report, we have demonstrated that definitive body cooling can be safely achieved earlier, before reaching the emergency department, by the field deployment of a BCU. In addition, our team was able to continue the resuscitation of the hyperthermic patients within the portable BCU. We believe that this additional capability of simultaneous resuscitation and monitoring effort confers an important advantage to this method of evaporative cooling.

In contrast to the findings by Costrini et al [15], the CK-MB was raised in all the patients. The increase in serum enzymes had been postulated to be derived from skeletal muscles and the liver [16]. The elevated troponin T was similarly demonstrated in other studies after prolonged exercises [17]. These findings would be consistent with the concept of cardiac “fatigue” or decreased myocardial contractility after prolonged strenu- ous exercises [18].

This report demonstrated the ability of the portable BCU to deliver definitive treatment of evaporative cooling out in the field to decrease the duration of hyperthermia in heat casualties.

Pang Hee-Nee MBBS, M Med(Orth)

Mong Rupeng MBBS Vernon J. Lee MBBS, MPH, MBA Wei-Chong Chua MBBS

Benjamin Seet MBBS, M Med(Surg)

SAF Medical Corps, Singapore E-mail address: [email protected]

doi:10.1016/j.ajem.2009.09.022

1	32/M	Heatstroke	41.9	39.0	30	0.10	63/20	129	110/51	110
2	38/M	Heatstroke	40.6	38.3	15	0.15	99/49	127	114/39	93
3	46/M	Heatstroke	41.0	38.7	20	0.12	98/59	129	121/61	118
4	20/M	Heat exhaustion	39.8	38.0	20	0.09	104/71	142	112/78	128
5	25/M	Heat exhaustion	40.0	37.0	15	0.2	136/62	130	124/56	109
6	25/M	Heat exhaustion	38.6	37.7	5	0.18	102/50	110	125/58	96
7	18/M	Heat exhaustion	39.2	37.8	10	0.14	106/78	117	128/84	92
BP indicates blood pressure; PR, pulse rate; M, male.

248 Correspondence

Table 2 Laboratory results for patients with EHI

Patient	CK (U/L)	CK-MB (ug/L)	Troponin T (ug/L)	Myoglobin (ug/L)	Aldolase (U/L)	Creatinine (umol/L)
1	3333	105	0.10	192	247	73
2	1395	7.7	0.07	1123	14.1	163
3	913	6.1	0.05	466	12.3	145
4	858	5.3	0.19	921	129	159
5	1115	13.4	0.07	142	23.3	82
6	567	6.9	0.05	203	15.6	104
7	489	8.9	0.07	b21	7.2	83
Laboratory results	Reference range
CK (U/L)	40-120
CK-MB (ug/L)	0.5-5.0
Troponin T (ug/L)	b0.03
Myoglobin (ug/L)	27.0-55.6
Aldolase (U/L)	2-12
Creatinine (umol/L)	63-110
CK (U/L)	40-120

References

1. Smith JE. Cooling methods used in the treatment of exertional heat illness. Br J Sports Med 2005;39:503-7.
2. Bouchama A, Knochel JP. Heat stroke. New Engl J Med 2002;346: 1978-88.
3. Armstrong LE, Crago AE, Adams R, et al. Whole-body cooling of hyperthermic runners: comparison of two field therapies. Am J Emerg Med 1996;14:355-8.
4. Gaffin SL, Gardner JW, Flinn SD. Cooling methods for heatstroke victims. Ann Intern Med 2000;132:678.
5. Weiner JS, Khogali M. A physiological body-cooling unit for treatment of heat stroke. Lancet 1980;1:507-9.
6. Armstrong LE, Casa DJ, Millard-Stafford M, Moran DS, et al. American College of Sports Medicine position stand. Exertional heat illness during training and competition. Med Sci Sports Exerc 2007;39:556-72.
7. SAF Medical Corps Preventive Medicine Directives-PM 20; 2006.

Accessed May 14, 2009.

1. 8Khogali M, Weiner JS. Heat stroke: report on 18 cases. Lancet 1980;2:276-8.
2. Heled Y, Rav-Acha M, Shani Y, et al. The “golden hour” for heatstroke treatment. Mil Med 2004;169:184-6.
3. Callaham ML. Emergency management of heat illness. Emergency Physician Series. North Chicago (Ill): Abbott Laboratories; 1979. p. 1-23.
4. Richards D, Richards R, Schofield PJ, et al. Management of heat exhaustion in Sydney’s the sun city to surf fun runners. Med J Aust 1979;2:457-61.
5. Mager M, Hubbard RW, Kerstein MD. Survey and analysis of the medical experience for CAX 8-80. Natick (Mass): Army Research Institute of Environmental Medicine, Technical Report; 1980.
6. Maron BJ, Doerer JJ, Haas TS, et al. Sudden deaths in young competitive athletes: analysis of 1866 deaths in the United States, 1980-2006. Circulation 2009;119:1085-92 [Epub 2009 Feb 16].
7. Pease S, Bouadma L, Kermarrec N, et al. Early organ dysfunction course, cooling time and outcome in classic heatstroke. Intensive Care Med 2009;35:1454-8 [Epub 2009 Apr 29].
8. Costrini, Pitt HA, Gustafson AB, et al. Cardiovascular and metabolic manifestations of heat stroke and severe heat exhaustion. Am J Med 1979;66:296-302.
9. Kew M, Bersohn I, Seftel H, et al. Liver damage in heatstroke. Am Med 1970;49:192-202.
10. Ohman EM, Armstrong PW, Christenson RH, et al. Cardiac troponin T levels for risk stratification in acute ischemia. N Engl J Med 1996;335: 1333-41.
11. Douglas PS, O’Toole ML, Hiller WD, et al. Cardiac fatigue after prolonged exercise. Circulation 1987;76:1206-13.

The impact of H1N1 influenza A virus pandemic on the emergency medical service in Kobe

To the Editor,

Pandemic H1N1 2009 influenza virus infection has been identified as the cause of a widespread outbreak of febrile respiratory tract infection. On June 11, 2009, the World Health Organization raised its pandemic alert to the highest level, phase 6.

The H1N1 influenza virus infection rapidly spread all over Japan after the first case was confirmed in Kobe, Japan, on May

16. The outbreak of this virus had a great impact on the Japanese society. There was a shortage in masks and antiseptic [1,2]. More than 4800 schools had been closed, medical services were swamped, many companies were forced into bankruptcy, and the stock market price declined [3,4]. Kobe suffered the most severe impact of the H1N1 influenza in Japan. Previous studies on severe acute respiratory syndrome [5] and the seasonal influenza [6] reported that emergency departments (EDs) were overcrowded in the epidemic and that the number of ED Ambulance diversion increased. Emergency medical service (EMS) was greatly influenced by the epidemic, whereas it remains unknown whether EMS

was influenced by the H1N1 influenza virus pandemic.

In Japan, the emergency paramedics are allowed to triage patients. When the emergency paramedics contact with patients, they negotiate with hospitalists to find a hospital where physicians can provide the medical support. To