Heat exhaustion and heat stroke.
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Heat Exhaustion↗
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[Heat exhaustion and heat stroke in the long distance runner].
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Athletic Injuries↗
Health tips. Treating heat exhaustion.
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Heat Exhaustion↗
Postural stability and neurobehavioural effects of heat exhaustion among adult men.
The medical complications of heat disorders, including haematological, cardiovascular and renal damage, have been well documented. However, very little has been written on its neurological complications. The objective of this study was to assess the effects of heat exhaustion on postural stability and neurobehavioral functions of men. The study is prospective in design and spans a 3-year period. All soldiers who were diagnosed to have heat exhaustion (cases) from 1 March 1998 to 31 August 1998 were included in the study. For each case, a healthy soldier (matched for age, ethnicity, years of education and military vocation) was recruited to serve as control. Each subject had a neurobehavioral assessment by using the Swedish Performance Evaluation System (SPES), a computerized test battery. The postural stability of the subjects was assessed using a computerized postural sway system. Findings for 37 heat exhaustion cases and 37 controls revealed that cases had a significantly higher prevalence of neurasthenia symptoms compared to the controls. There were significant (small) differences between the cases and controls in the neurobehavioral tests of choice reaction time, digit span and some parts of colour word stress and logical series measures. Postural stability in the cases was significantly poorer when in the "eyes-closed" condition, compared with the controls. Men with heat exhaustion, studied 2 weeks after the acute episode, had significantly more symptoms of neurasthenia, poorer performance in short-term memory and slower reaction time. The cases (as a group) had significantly poorer postural stability.
Adult↗
Heat exhaustion in a deep underground metalliferous mine.
OBJECTIVES: To examine the incidence, clinical state, personal risk factors, haematology, and biochemistry of heat exhaustion occurring at a deep underground metalliferous mine. To describe the underground thermal conditions associated with the occurrence of heat exhaustion. METHODS: A 1 year prospective case series of acute heat exhaustion was undertaken. A history was obtained with a structured questionnaire. Pulse rate, blood pressure, tympanic temperature, and specific gravity of urine were measured before treatment. Venous blood was analysed for haematological and biochemical variables, during the acute presentation and after recovery. Body mass index (BMI) and maximum O2 consumption (VO2 max) were measured after recovery. Psychrometric wet bulb temperature, dry bulb temperature, and air velocity were measured at the underground sites where heat exhaustion had occurred. Air cooling power and psychrometric wet bulb globe temperature were derived from these data. RESULTS: 106 Cases were studied. The incidence of heat exhaustion during the year was 43.0 cases/million man-hours. In February it was 147 cases/million man-hours. The incidence rate ratio for mines operating below 1200 m compared with those operating above 1200 m was 3.17. Mean estimated fluid intake was 0.64 l/h (SD 0.29, range 0.08-1.50). The following data were increased in acute presentation compared with recovery (p value, % of acute cases above the normal clinical range): neutrophils (p < 0.001, 36%), anion gap (p < 0.001, 63%), urea (p < 0.001, 21%), creatinine (p < 0.001, 30%), glucose (p < 0.001, 15%), serum osmolality (p = 0.030, 71%), creatine kinase (p = 0.002, 45%), aspartate transaminase (p < 0.001, 14%), lactate dehydrogenase (p < 0.001, 9.5%), and ferritin (p < 0.001, 26%). The following data were depressed in acute presentation compared with recovery (p value, % of acute cases below the normal clinical range): eosinophils (p = 0.003, 38%) and bicarbonate (p = 0.011, 32%). Urea and creatinine were significantly increased in miners with heat cramps compared with miners without this symptom (p < 0.001), but there was no significant difference in sodium concentration (p = 0.384). Mean psychrometric wet bulb temperature was 29.0 degrees C (SD 2.2, range 21.0-34.0). Mean dry bulb temperature was 37.4 degrees C (SD 2.4, range 31.0-43.0). Mean air velocity was 0.54 m/s (SD 0.57, range 0.00-4.00). Mean air cooling power was 148 W/m2 (SD 49, range 33-290) Mean psychrometric wet bulb globe temperature was 31.5 degrees C (SD 2.0, range 25.2-35.3). Few cases (< 5%) occurred at psychrometric wet bulb temperature < 25.0 degrees C, dry bulb temperature < 33.8 degrees C, air velocity > 1.56 m/s, air cooling power > 248 W/m2, or psychrometric wet bulb globe temperature < 28.5 degrees C. CONCLUSION: Heat exhaustion in underground miners is associated with dehydration, neutrophil leukocytosis, eosinopenia, metabolic acidosis, increased glucose and ferritin, and a mild rise in creatine kinase, aspartate transaminase, and lactate dehydrogenase. Heat cramps are associated with dehydration but not hyponatraemia. The incidence of heat exhaustion increases during summer and at depth. An increased fluid intake is required. Heat exhaustion would be unlikely to occur if ventilation and refrigeration achieved air cooling power > 250 W/m2 at all underground work sites.
Acute Disease↗
Heat intolerance, heat exhaustion monitored: a case report.
A 32-year-old male (Mr. A.), monitored during an 8-d heat acclimation (HA) investigation, unexpectedly exhibited heat intolerance and heat exhaustion. Thirteen other males completed HA without indications of either heat intolerance or heat exhaustion. Because Mr. A. responded normally to HA on days 1-4, the intervention of an unknown host factor on days 5-8 was suggested. Mr. A.'s heat exhaustion episode (day 8) was apparently forewarned by loss of body weight and increased delta HR, delta Tsk (days 5-8) and delta Tre (days 7-8) during daily 90-min trials. His symptoms indicated classical salt depletion heat exhaustion, but the calculated salt deficit (less than 0.1 g NaCl.kg-1 body weight) was mild. Post-heat exhaustion serum enzyme levels were either normal (ALT, AST) or acutely elevated (CPK). Blood beta-endorphin and cortisol levels were six times and two times greater than control values, respectively. This case report is unique because clinical/physiological measurements and blood analyses were performed before, during, and after heat intolerance and heat exhaustion.
Acclimatization↗
The risk of heat exhaustion at a deep underground metalliferous mine in relation to surface temperatures.
The risk of heat exhaustion at a deep underground metalliferous mine was assessed in relation to thermal conditions prevailing on the surface. For each day of a 1-year prospective case series of heat exhaustion, surface 24-h mean wet and dry bulb temperatures were recorded. From this data, 24-h mean wet bulb globe temperatures were derived using certain assumptions. The three surface temperature variables were significantly higher on those days on which heat exhaustion occurred, compared to those days on which it did not occur (P < 0.001). The relative risk of heat exhaustion on days when the 24-h mean wet bulb globe temperature was in the range 26.0-28.0 degrees C was 4.82 (95% confidence interval 2.12-10.96). Surface temperature data could be used at this mine to warn miners about the risk of heat exhaustion.
Acute Disease↗
Management of heat exhaustion in Sydney's the Sun City-to-Surf run runners.
Heat exhaustion (collapse with rectal temperature of, or higher than 38 degrees C) is the most common major medical complication of fun runs and is caused by dehydration and impaired heat loss with, or without, hypoglycaemia. All patients with heat exhaustion after the City-to-Surf runs from 1977 to 1979 were managed in a medical centre established at the finish of the course. Several methods of management of heat exhaustion are evaluated. Patients were allocated retrospectively to four primary treatment groups: (i) treated with ice-wet towels only; (ii) treated with ice-wet towels and intravenously administered fluids; (iii) treated with intravenously administered fluids and ice-cold packs applied to the neck, axillae, and groins; and (iv) treated with intravenously administered fluids only. There was no death or prolonged morbidity in any treatment group. In Group 1 (n=11), the mean initial rectal temperature was 40.2 +/- 1.5 degrees C. There were insufficient data to assess the mean time taken for the temperature to fall to 38 degrees C. In Group 2(n=16), the mean initial rectal temperature was higher than 40.9 +/- 1.1 degrees C. In three patients, the temperature failed to fall to 38 degrees C within 90 minutes. For the remainder, the mean time taken for the temperature to fall to 38 degrees C was 30 minutes. In Group 3 (n=16), the mean initial rectum temperature was higher than 41.2 +/- 1.0 degrees C. One patient, who had been febrile immediately before the run, was discharged with a temperature of 38.8 degrees C. For the remainder, the mean time taken for the temperature to fall to 38 degrees C was 36 +/- 10 minutes. In Group 4 (n=13), the mean initial rectal temperature was 39.6 +/- 1.1 degrees C and the mean time taken for the temperature to fall to 38 degrees C was 21 +/- 16 minutes. Heat exhaustion in fun-run casualties may be safely and effectively treated by rapid intravenous infusion of fluids with, or without, application of cold packs to the neck, axillae, and groins. The application of ice-wet towels is contraindicated.
Adolescent↗
Heat exhaustion in The Sun-Herald City to Surf fun run.
OBJECTIVE: To investigate the relationship between motivational factors and physical and biological causes of heat exhaustion in fun run entrants. DESIGN AND SETTING: Case-control study, The Sun-Herald City to Surf fun runs in Sydney in 1991 and 1992. PARTICIPANTS: There were 63,732 race entrants who completed the run and received a finishing time; 79 runners with heat exhaustion and 310 age, sex and performance matched controls were enrolled in the study. MAIN OUTCOME MEASURE: A diagnosis of heat exhaustion was made if a runner collapsed and, when first receiving medical care, had a rectal temperature of 38 degrees C or higher. RESULTS: Two readily identifiable groups of runners were at high risk of heat exhaustion--accomplished non-élite (preferred) runners and runners of good ability (Group A). The attack rate was highest among accomplished non-élite runners, but a combination of a relatively high rate and the large number of entrants in Group A runners accounted for most cases. Four major risk factors for heat exhaustion were identified: motivation to exceed previous performance targets; failure to drink fluids during the run; failure of trained runners to acclimatise for the race by training in the warmer parts of the day; and previous history of heat exhaustion. CONCLUSION: Information from this investigation will enable more effective targeting of educational prevention programs in The Sun-Herald City to Surf fun run and provide baseline data for monitoring the effectiveness of these programs to modify high risk behaviour by participants.
Adolescent↗
Prognosis of adult men with heat exhaustion with regard to postural stability and neurobehavioral effects: a 6-month follow-up study.
The medical complications of heat disorders, including hematological, cardiovascular and renal damage, have been well documented. However, very little has been written on its neurological complications. In an earlier study, we reported that men with heat exhaustion, studied 2 weeks after the acute episode, had significantly more symptoms of neurasthenia, poorer performance in short-term memory and slower reaction time. The cases (as a group) had significantly poorer postural stability. The objective of this study was to assess the prognosis of men with heat exhaustion with regard to postural stability and neurobehavioral functions 12, 3 and 6 months after the acute episode. The study is prospective in design and spans a 2-year period. All soldiers who were diagnosed to have heat exhaustion (cases) from 1 March 1998 were included in the study. For each case, a healthy soldier (matched for age, ethnicity, years of education and military vocation) was recruited to serve as control. Each subject had a neurobehavioral assessment by using the Swedish Performance Evaluation System (SPES), a computerized test battery. The postural stability of the subjects was assessed using a computerized postural sway system. Each subject took the test 2 weeks after the acute episode and repeated the test 3 and 6 months later for duration of 2 years. We report here the findings of 21 heat exhaustion cases and 18 controls, which completed all the three tests (i.e. done 2 weeks after the acute episode and 3 and 6 months later). Significant differences were only detected in some of the neurobehavioral and neurophysiological parameters between the cases and the control for first two tests but not the third test. The prognosis of adult with heat exhaustion is good. There were no significant differences in neurobehavioral tests and postural stability among the cases and controls 612 months after the episode.
Adolescent↗
Acute myocardial infarction in a young man after heat exhaustion.
A 33-year-old man with heat exhaustion was admitted to our hospital suffering from severe chest pain. Serum creatine kinase elevation and new Q waves revealed myocardial infarction of the inferior wall. Technetium-99m-pyrophosphate suggested diffuse myocardial damage, although the left ventricular function was normal by echocardiography. This case highlights the importance of early recognition of heat stroke and heat exhaustion, as they are associated with widespread tissue injury.
Adult↗
The risk of heat exhaustion at a deep underground metalliferous mine in relation to body-mass index and predicted VO2max.
The risk of heat exhaustion at a deep underground metalliferous mine was assessed in relation to the body-mass index (BMI) and predicted maximal oxygen uptake (VO2max) of miners, using case-control methodology. Sixty-five cases of acute heat exhaustion and 119 controls were studied. Heat exhaustion cases had a significantly higher BMI than controls (P = 0.006). The odds ratios increased with BMI. For a BMI of 32.00-36.99, compared to a BMI of less than 27.00 the odds ratio was 3.63 (95% confidence interval, 1.42-9.36). VO2max was not significantly lower in cases than controls. The odds ratios for heat exhaustion increased with decreasing VO2max, but not significantly. The sample size provided 80% power of detecting an odds ratio of 2.5 or greater. Deep underground miners should be advised to maintain a BMI of 24-27. Selection of miners on the basis of BMI should not be used as an alternative to satisfactory engineering controls such as ventilation and refrigeration.
Adult↗
Echocardiographic and Doppler study of patients with heatstroke and heat exhaustion.
This is a two-dimensional and Doppler echocardiographic study of the hemodynamic changes in patients with heatstroke and heat exhaustion. It demonstrates that the hemodynamic changes in severe heat exposure reflect a hyperdynamic circulation with tachycardia and high cardiac output states. Relative hypovolemia was more pronounced in patients with heatstroke compared to patients with heat exhaustion. Signs of peripheral vasoconstriction were more often present in patients with heatstroke, while patients with heat exhaustion more often demonstrated peripheral vasodilatation.
Cardiac Output↗
Heat exhaustion during mass pilgrimage--is there a diagnostic role for pulse oximetry?
Every year over 2 million pilgrims (Hajjis) gather from different countries to perform the sacred ritual, the fifth pillar of Islam, Hajj. Several nationalities from different climates come to Saudi Arabia which is located in a subtropical area with a hot and humid climate during the long summer season. This undertaking is characterised by several days of continuous physical, spiritual, and emotional exertion following their homeland. Several factors predispose them to heat exhaustion, such as the hot climate, excessive physical exercise, lack of acclimatisation, overcrowding, illiteracy, old age, diseases, and over zealous performance of Hajj during the peak sunshine hours. Several thousands of pilgrims suffer from heat exhaustion which is a minor form of heat illness that can easily be detected and treated. Patients are usually discharged having fully recovered, but if heat exhaustion is not treated immediately, it may result in heat stroke with serious sequelae. Cases that need further observation and management are admitted to hospital, particularly those who have associated medical disorders. This study was designed to investigate the role of pulse oximetry in detecting hypoxaemia in patients suffering from heat exhaustion. One hundred fifty-five patients from 26 different countries were enrolled in this study. Their ages ranged from 18 to 83 years. There were 51 (33%), 48 (31%), and 56 (36%) from Asia, the Middle East and Africa, respectively. One hundred thirty-four patients (86.5%) showed a form of hypoxia which necessitated O2 administration. Mild hypoxia (91-94% O2 saturation) was detected in 81 patients (52.3%) and moderate to severe hypoxia (< 90% O2 saturation) was detected in 53 (34.2%) patients.
Adolescent↗
Acute anhidrotic heat exhaustion.
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Heat Exhaustion↗
Infrared thermometry in the diagnosis and treatment of heat exhaustion.
Infrared (IR) thermometers (FirstTemp 2000A, Intelligent Medical Systems, California) were used to monitor tympanic temperature (Tty) in 12 collapsed fun-runners suspected of suffering exertion-induced heat exhaustion (EIHE). Rectal temperature (Tre) was monitored via digital clinical thermometers. Conditions during the fun-run and in the field treatment centre were cool (air temperature 16-18 degrees C, relative humidity 60-65%). On admission, Tty was (mean +/- SEM) 1.2 +/- 0.3 degrees C lower than Tre. For admission plus subsequent monitoring data pooled, although Tty correlated significantly with Tre (r = 0.86, p < 0.001), mean Tty (37.4 +/- 0.2 degrees C) was significantly lower (p < 0.01) than mean Tre (38.4 +/- 0.4 degrees C). Cotton wool ear pads, applied to 10 of the runners on admission to minimise environmental effects on Tty, did not significantly improve the IR monitoring. A Tty > or = 37.1 degrees C predicted a Tre > or = 38 degrees C (an established diagnostic criterion for EIHE) with a sensitivity of 0.93 and a specificity of 0.63. These data indicate that IR tympanic thermometry, when utilised in cool environments, can result in misdiagnosis of heat exhaustion. Although IR thermometry shows some promise as a rapid, non-invasive means of monitoring core temperature, it should not be used in the diagnosis and treatment of heat exhaustion unless further research validates the method.
Adult↗
Cardiovascular and metabolic manifestations of heat stroke and severe heat exhaustion.
We prospectively studied the clinical, biochemical (including creatine phosphokinase (CPK) isoenzymes) and electrocardiographic features of exertional heat stroke in 13 patients (group 1) and severe heat exhaustion in 14 patients (group 2). Despite initial presentations with severe hyperthermia, tachycardia and hypotension, only one patient with heat stroke had myocardial ischemia. The CPK isoenzymes were not indicative of myocardial damage in any patient. The patients with heat stroke were somewhat more dehydrated than those with heat exhaustion as measured by differences in serum creatinine, sodium and osmolality, and the former (group 1) had a significantly lower initial glucose level (P less than 0.05). Although significant differences in potassium were not observed in the pretreatment samples, at 12 hours the serum potassium was significantly lower in group 1 (P less than 0.05). This suggests that this group may have been more potassium-depleted at the time of heat stroke. Prompt recognition and vigorous therapy were successful in rapidly lowering high temperatures and in preventing serious complications.
Alanine Transaminase↗
Exertion-induced heat exhaustion. An often overlooked diagnosis.
Exertion-induced heat exhaustion is a potentially lethal condition. The earliest signs include unsteady gait and confusion. Recording of rectal temperature is essential. Skin colour, blood pressure and heart rate are not reliable diagnostic signs. The mainstays of therapy are rapid rehydration and cooling. Prompt diagnosis and rapid effective therapy will minimise the risk of death.
Adult↗