Exertional heat stroke and acute renal failure in a young woman

Where do you live and what do you do? Two questions that might impact your kidney health

In many cases the social determinants of health need to be assessed through their interaction with environmental factors. This review looks at the impact of physical location and occupation of individuals on their kidney health. It examines the effect of living at high altitude on kidney function and the relationship between extreme cold or hot temperatures and the incidence of kidney injury. It reviews as well the many occupations that have been linked to kidney disease in high-income and low-and-middle-income countries. As a conclusion, this overview proposes preventive recommendations that could be individualized based on weather, altitude, socio-economic level of the country and occupation of the individual.

Prognostic significance of disseminated intravascular coagulation in patients with heat stroke in a nationwide registry

PURPOSE

Heat stroke (HS) induces disseminated intravascular coagulation (DIC); however, the prognostic significance of DIC in patients with HS has not yet been fully assessed in large populations. The aim of this study was to examine the prognostic significance of DIC in patients with HS using a nationwide registry.

MATERIALS AND METHODS

Data regarding HS were obtained and analyzed from three prospective, observational, multicenter HS registries (HSRs): 2010, 2012, and 2014. Univariate and multivariate analyses were performed to identify independent predictors of hospital death. DIC was diagnosed according to the Japanese Association for Acute Medicine (JAAM) diagnostic criteria, with a total score≥4 implying a DIC diagnosis.

RESULTS

In total, 705 (median age, 68years; 501 men) were included in this study. Hospital mortality was 7.1% (50 patients). Multiple regression analysis revealed that hospital mortality was significantly associated with presence of DIC (odds ratio [OR], 2.16; 95% confidence interval [CI], 1.09-4.27; p=0.028). Mortality worsened as the DIC score increased, and increased remarkably to approximately 10% when the DIC score was 2.

CONCLUSIONS

Presence of DIC was an independent prognostic factor of hospital mortality in patients with HS. Hematological dysfunction represents potential target for specific therapies in HS.

Acute kidney injury associated with endurance events-is it a cause for concern? A systematic review

INTRODUCTION

A growing body of evidence suggests even small rises in serum creatinine (SCr) are of considerable clinical relevance. Given that participants in endurance events are exposed to potential (repeated) renal insults, a systematic review was undertaken to collate current evidence for acute kidney injury (AKI), complicating such events.

METHODS

A systematic review of studies and case reports meeting inclusion criteria on Medline and EMBASE (inception to October 2015). Included: studies with markers of renal function before and after endurance or ultraendurance events; case reports of severe AKI. Two reviewers assessed risk of bias using the Newcastle-Ottawa scale.

RESULTS

Eleven case report publications (n=27 individuals) of severe AKI, were retrieved, with risk factors including systemic illness or nephrotoxic medications usually identified. From 30 studies of endurance and ultraendurance events, mean rise in SCr was 29 (±12.3) µmol/L after marathon or ultramarathon (17 studies, n=568 participants) events. Where follow-up tests were conducted, SCr returned to baseline within 48 hours. Rises in biomarkers suggest potential parenchymal insult, rather than simply muscle breakdown. However, evidence of long-term deleterious effects is lacking.

CONCLUSIONS

Raised levels of SCr are reported immediately after endurance events. It is not clear whether this is either clinically significant, or if repeated participation predisposes to long-term sequelae. The aetiology of severe exercise-associated AKI is usually multifactorial, with risk factors generally identified in the rare cases reported. On-site biochemistry, urine analysis and biomarkers of AKI may help identify collapsed runners who are at significant short-term risk and allow suitable follow-up.

Urine dipstick analysis for identification of runners susceptible to acute kidney injury following an ultramarathon

This study examined whether urine dipstick testing might be useful to predict the development of acute kidney injury after an ultramarathon. Participants in the 2011 161-km Western States Endurance Run underwent post-race blood and urine dipstick analyses. Of the 310 race finishers, post-race urine dipstick testing was completed on 152 (49%) and post-race blood also was obtained from 150 of those runners. Based on "injury" and "risk" criteria for acute kidney injury of blood creatinine 2.0 and 1.5 times estimated baseline, respectively, 4% met the criteria for injury and an additional 29-30% met the criteria for risk of injury. Those meeting the injury criteria had higher creatine kinase concentrations (P < 0.001) than those not meeting the criteria. Urine dipstick tests that read positive for at least 1+ protein, 3+ blood, and specific gravity ≥ 1.025 predicted those meeting the injury criteria with sensitivity of 1.00 (95% confidence interval [CI] 0.54-1.00), specificity of 0.76 (95% CI 0.69-0.83), positive predictive value of 0.15 (95% CI 0.06-0.30), negative predictive value of 1.00 (95% CI 0.97-1.00), and likelihood ratio for a positive test of 4.2. We conclude that urine dipstick testing was successfully able to identify those individuals meeting injury criteria for acute kidney injury with excellent sensitivity and specificity.

The effects of prolonged endurance exercise on the neurological system in horses

Horses compete routinely in endurance-type activities. Many of the various pathophysiological mechanisms which arise during endurance exercise have implications for the health and function of the neurological system. The development of centrally-mediated fatigue is a normal homeostatic physiological event with several possible mechanisms. Development of pathophysiological phenomena such as cerebral oedema may be near-terminal events during or after endurance exhaustion. Cellular damage resulting in cytotoxic cerebral oedema may result from decreases in circulating blood volume (dehydration), blood pressure, oxygen, and glucose, or increases in brain temperature. Vasogenic cerebral oedema arises from changes in cerebral vascular perfusion, tone, and permeability. Increased vascular permeability results from increased brain temperature, poor vascular integrity due to severe dehydration, disseminated intravascular coagulation due to hemoconcentration or endotoxemia, and iatrogenic overhydration during therapy. Clinical signs of intracranial disease after endurance exercise include staggering, shaking, ataxia, paresis, poor tongue tone, facial twitching, collapse, recumbency, seizures, and death. Treatment should include active and aggressive cooling, intravenous polyionic fluids, acid-base imbalance correction, intravenous glucose and calcium supplementation, non-steroidal anti-inflammatory agents once the patient is better hydrated, intra-nasal oxygen therapy if practicable, and achievement of a non-dependent head posture to prevent jugular venous hypertension and further increases in intracranial pressure. The prognosis for central fatigue is good with appropriate supportive care, but the prognosis for successful treatment of cerebral oedema must be considered guarded at best. Prevention is critical and must be through incorporation of mandatory rest stops with sufficient length and veterinary monitoring to allow prevention and detection of exhaustion, excessive dehydration, and neurological signs. Management flexibility in shortening or postponing rides in hot and humid conditions, mandated use of aggressive cooling techniques, and more restrictive entry criteria for upper level Fédération Equestre Internationale races should all be considered as viable options for optimising the safety of endurance horses.

Maximal exercise and muscle energy metabolism after recovery from exercise hyperthermia syndrome

Muscle energy metabolism was studied in 30 subjects after recovery from exercise hyperthermia syndrome (EHTS subjects) and 15 healthy men with identical physical activities. Blood lactate, free fatty acid (FFA), serum creatine kinase activity (CK), and glycerol and the temperature in the auditory duct (T(c)) and on the thumb pad (T(sk)) were measured at rest and during and after maximal exercise on a cycloergometer. The EHTS subjects had a limitation of physical performance, with lowered values for maximal oxygen uptake (VO(2max), P < 0.0005), maximal workload (P < 0.05), and ventilatory threshold (V(t), P < 0.0005). The discrepancy between high plasma concentrations of FFA and the lack of decrease in respiratory ratio (RR) suggests that, in EHTS subjects, a very active release of FFA was not balanced by a proportional increase in catabolism. The increased skin temperature was smaller in EHTS subjects (P < 0.05 at 180 and 200 W). At the end of exercise, auditory duct temperature increase was higher in EHTS subjects than in control subjects (P < 0.05). This study thus showed an impairment of muscle metabolism and an abnormality of thermoregulatory mechanisms. These results may provide insight into the underlying physiopathological disturbance.

Adverse events associated with eccentric exercise protocols: six case studies

PURPOSE

Rhabdomyolysis is a condition characterized by muscle damage and degeneration of muscle cells after strenuous, overexertion exercise. Although the incidence of severe rhabdomyolysis is rare, this condition can be dangerous and even fatal. Eccentric exercise protocols are currently being used to induce and study mild forms of muscle damage. However, serious adverse events can occur in these laboratory investigations. The purpose of this report was to expose some of the adverse events resulting from performance of eccentric exercise protocols to study muscle damage in humans.

METHODS

The following case studies involved an eccentric exercise protocol where two sets of 25 maximal eccentric actions of the elbow flexors were performed, separated by a 5-min rest period.

RESULTS

Case reports are presented that reveal prolonged losses in the ability of the muscle to generate force lasting 43-47 d, extreme swelling of the exercised arm lasting several weeks, and greatly elevated serum creatine kinase levels.

CONCLUSIONS

Although adverse events resulting from eccentric exercise are rare, our laboratory has observed a 3% incidence rate during the past year. Investigators should be knowledgeable of the sequelae of events that are associated with muscle damage after high-force eccentric exercise and take appropriate precautions.

Exertional heat stroke in a young woman: gender differences in response to thermal stress

Exertional heat stroke (EHS) is an acute life-threatening emergency that necessitates the immediate institution of cooling measures. Reported here is a case of EHS in a nonacclimatized young woman who was undergoing strenuous exercise. The patient developed many of the characteristic features of EHS, including central nervous system disturbances, lactic acidosis, rhabdomyolysis, coagulopathy, and abnormal myocardial conduction. While EHS is relatively common in young men, the condition is rare in women. This case presentation addresses gender differences in the response to the thermal stress of intense physical activity.

Renal failure and heatstroke

We report a fatal case of heatstroke in an obese boy who developed multi-organ failure. Six other cases of exertional heatstroke admitted to our hospital over the last 5 years were also reviewed. All of them showed some degree of renal impairment. The causes of renal failure are multifactorial, with rhabdomyolysis being the major mechanism. All cases except one responded to alkaline diuresis without the need for dialysis. Continuous venovenous hemofiltration appeared to be a good alternative in hemodynamically unstable patients. Renal function recovered completely after varying intervals in all surviving cases. Interestingly, rhabdomyolysis in our heatstroke patients was usually associated with hypokalemia or normokalemia instead of hyperkalemia. Mortality in our series was largely related to the long duration of hyperthermia and coma, the severity of disseminated intravascular coagulation, and the presence of cardiogenic shock and severe acidosis.

Environment-dependent sports emergencies

As more individuals participate in sports and outdoor activities, the frequency of environmentally related illnesses will increase. Participants in sporting events of long duration and those requiring particularly inclement weather and adverse conditions are especially prone to developing injury. Hypothermia, heat-related illnesses, and high-altitude illnesses are multisystem emergencies that require immediate, specific therapeutic maneuvers. Physicians must be able to recognize the signs and symptoms of these medical emergencies and institute definitive care. Rapid core rewarming, airway control, and prolonged cardiopulmonary resuscitation are the key factors in managing the hypothermic patient. Adequate cooling and volume resuscitation provide the basis for treating the hyperthermic patient. The patient with high altitude-related illness should be returned to a lower elevation and given supplemental oxygen. Specific intervention depends on the patient's presentation. Environmental illnesses cause severe morbidity and mortality and are frequently within the control of the sport participant. Thus physicians must educate their patients on basic preventive measures if they are going to participate in outdoor sporting activities.