Evidence of prolonged myocardial dysfunction in heat stroke

New observations support William Osler's rationale for systemic bloodletting

Bloodletting has been called William Osler's "blind spot," especially with respect to pneumonia. Also puzzling has been his endorsement of bleeding in selected cases of heatstroke. Recent clinical observations on pneumonia and, to a lesser extent, heatstroke lend support to Osler's rationale for bloodletting in these conditions. A 21st-century rationale now exists for all eight indications for systemic bloodletting listed by Osler in the first edition of his textbook, The Principles and Practice of Medicine (1892): treatment of acute heart failure (seven of the eight indications) or rapid lowering of blood pressure (in subarachnoid hemorrhage accompanied by severe hypertension). These observations support the narrative that during Osler's lifetime, bloodletting became more "rational" largely on the basis of cumulative clinical experience.

Severe heatstroke complicated with Takotsubo cardiomyopathy

Case

A 69 year-old female with history of schizophrenia was transported to our hospital by ambulance due to coma. On arrival, she was hypotensive and tachycardic with a Glasgow coma scale score of 3 and a rectal core temperature of 40°C. Heatstroke was strongly suspected as the cause of the coma and hypotension. Active external cooling with an electric fan and cooled IV fluid administration were started. Her electrocardiogram (EKG) showed ST elevation in V2-6, II, III and aVF. Echocardiography revealed apical ballooning, which indicated Takotsubo cardiomyopathy. Coronary angiography indicated normal coronary arteries.

Outcome

After admission to the intensive care unit, her cardiovascular status gradually improved and she was transferred to the psychiatric ward on day 36.

Conclusion

Heatstroke and Takotsubo cardiomyopathy can share the same pathophysiology. Close evaluation of hemodynamic status and myocardial damage is critical for survival.

Heat Stroke-Induced Sinoatrial Node Dysfunction

BACKGROUND

Heat stroke has been associated with stress-induced cardiomyopathy and electrocardiogram ST segment elevation and depression. Laboratory studies with dogs have demonstrated heat stroke-induced sinoatrial node dysfunction in the setting of hyperkalemia. No prior case report has described heat stroke-induced complete sinoatrial node dysfunction that resolved in the emergency department.

CASE REPORT

An 87-year-old female presented to the emergency department with heat stroke and severe bradycardia. Initial electrocardiogram demonstrated complete sinoatrial node dysfunction. The bradycardia responded to external cardiac pacing and the sinoatrial node dysfunction resolved with aggressive cooling. Emergency physicians should be aware that heat stroke can cause complete sinoatrial node dysfunction and that this bradydysthrmia can be treated with aggressive cooling.

Exertional Heat Stroke – The Athlete's Nemesis

Heat stroke represents the extreme end of a spectrum of heat-related illnesses. It can occur in endurance athletes. Its incidence is probably under-reported. Patients present confused, drowsy or comatose, with a raised core temperature, but often a falsely reassuring peripheral temperature. Treatment is centred on reducing the core temperature as rapidly as possible and appropriate supportive management. Even with prompt treatment, it is associated with multi-organ dysfunction and death. Patients are often misdiagnosed, or diagnosed late. This is probably exacerbated by a wide differential diagnosis, the need for a core temperature measurement to reach the diagnosis and clinicians being unfamiliar with the disease. The need for immediate recognition, and immediate treatment compounds the problem. Survivors may experience long-term neurological disability and may be at risk of a further episode. Patients should return to sport gradually and only when they feel well. Its epidemiology, pathophysiology and clinical management are reviewed.

Early organ dysfunction course, cooling time and outcome in classic heatstroke

PURPOSE

To describe the course of early organ dysfunction in a cohort of patients admitted in ICU suffering classic heatstroke.

METHODS

Prospective observational single-centre cohort study with a 1-year follow-up.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Clinical and biological data of 22 patients were analysed. Median body temperature on admission was 41.1 degrees C. Respiratory, circulatory, haematological, hepatic and renal function all deteriorated within the first 24 h of admission. ICU-mortality was 63.6%. Cooling time, serum lactate, serum cardiac troponin I and creatinine were significantly higher in non-survivors. Early ICU-mortality (within 7 days of ICU stay) was due to multiple organ failure. Late ICU-mortality was due to neurological disability.

CONCLUSIONS

Classic heat stroke may demonstrate a rapidly worsening organ dysfunction course leading to death even though cooling procedures and intensive care management are promptly started.

Cooling and hemodynamic management in heatstroke: practical recommendations

Introduction

Although rapid cooling and management of circulatory failure are crucial to the prevention of irreversible tissue damage and death in heatstroke, the evidence supporting the optimal cooling method and hemodynamic management has yet to be established.

Methods

A systematic review of all clinical studies published in Medline (1966 to 2006), CINAHL (Cumulative Index to Nursing & Allied Health Literature) (1982 to 2006), and Cochrane Database was performed using the OVID interface without language restriction. Search terms included heatstroke, sunstroke, and heat stress disorders.

Results

Fourteen articles reported populations subjected to cooling treatment for classic or exertional heatstroke and included data on cooling time, neurologic morbidity, or mortality. Five additional articles described invasive monitoring with central venous or pulmonary artery catheters. The four clinical trials and 15 observational studies covered a total of 556 patients. A careful analysis of the results obtained indicated that the cooling method based on conduction, namely immersion in iced water, was effective among young people, military personnel, and athletes with exertional heatstroke. There was no evidence to support the superiority of any one cooling technique in classic heatstroke. The effects of non-invasive, evaporative, or conductive-based cooling techniques, singly or combined, appeared to be comparable. No evidence of a specific endpoint temperature for safe cessation of cooling was found. The circulatory alterations in heatstroke were due mostly to a form of distributive shock associated with relative or absolute hypovolemia. Myocardial failure was found to be rare.

Conclusion

A systematic review of the literature failed to identify reliable clinical data on the optimum treatment of heatstroke. Nonetheless, the findings of this study could serve as a framework for preliminary recommendations in cooling and hemodynamic management of heatstroke until more evidence-based data are generated.

Thoracic cavity irrigation: an unusual cause of acute ST segment increase

IMPLICATIONS

We describe an unusual case of acute ST segment increase secondary to warm saline thoracic cavity irrigation during thoracotomy. Temperature-mediated alteration of myocyte repolarization should be considered in addition to myocardial ischemia when ST segment changes occur.

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.

Non-invasive evaluation of cardiac abnormalities in heat stroke pilgrims

Serial electrocardiograms as well as echocardiographic studies of 51 pilgrims suffering from acute heat stroke (mean rectal temperature 41.6 degrees C) were performed. All patients were examined immediately after cooling and 24 h later whenever possible. Regional wall motion abnormalities were detected in 9 cases (17.6%) while pericardial effusion was observed in 13 cases (25%) and asymmetrical septal hypertrophy was detected in 8 cases (15.6%). Other cardiac abnormalities included right ventricular dilatation and increased in left ventricular internal dimensions in 4 cases (7.8%), respectively. Thirteen cases (25.5%) had normal echocardiographic findings. Forty (78%) patients had sinus tachycardia while 8 cases (15.7%) showed atrial fibrillation with uncontrolled ventricular rate, and 3 (5.8%) had sinus bradycardia. Heat stroke electrocardiograms showed tracings demonstrating ST segment depression, compatible with ischaemia in 9 cases, while in 6 cases there were nonspecific T wave changes, whereas in another 4 cases the tracings demonstrated different conduction abnormalities. The collected data were analysed and compared to those of 43 control patients. The adverse effects of heat stroke on the heart are multifactorial requiring the utmost attention and understanding, as they reflect the patient's cardiovascular status.

The role of noncardiac disease in the development and precipitation of heart failure

The varying roles of a widely diverse group of noncardiac disorders on the heart, particularly their ability to induce heart failure, are explored. A general overview of the cardiac effects of volume and pressure overloading is followed by specific discussions of the roles of vascular, endocrine and metabolic, renal, gastrointestinal, central nervous system, hematologic, and other miscellaneous disorders (heat stroke, sepsis, immune-mediated disease, obesity, malnutrition, and pregnancy) in producing cardiac dysfunction and failure in companion animals. Pathogenetic and pathophysiologic mechanisms are emphasized.