What are the side effects of hyperthermia?

Side Effects of Hyperthermia

Hyperthermia causes a cascade of life-threatening metabolic complications including rhabdomyolysis, hyperkalaemia, cardiac arrhythmias, acidosis, disseminated intravascular coagulopathy, compartment syndrome, and acute renal injury, with mortality remaining at approximately 4% even with optimal treatment. 1, 2

Cardiovascular Complications

• Tachyarrhythmias are the most frequent cardiac manifestation, driven by sympathetic nervous system activation and metabolic stress 1
• Cardiac arrhythmias develop secondary to hyperkalaemia and acidosis, requiring specific management beyond standard protocols 1
• Hemorrhagic diathesis affecting multiple organ systems can directly contribute to death 3

Metabolic Derangements

• Severe acidosis results from excessive carbon dioxide production and anaerobic metabolism, with low pH values associated with poor outcomes 1
• Hyperkalaemia occurs from massive cellular breakdown and requires urgent treatment with sodium bicarbonate and glucose/insulin, though calcium should only be used in extremis due to concerns about worsening intracellular calcium overload 1
• Massive rhabdomyolysis leads to muscle swelling, elevated creatine kinase, and myoglobinuria 1

Renal and Hematologic Complications

• Acute occlusive renal injury develops from rhabdomyolysis and myoglobinuria, requiring aggressive fluid resuscitation to maintain urine output >2 ml/kg/hour 1
• Compartment syndrome can occur from severe muscle swelling associated with rhabdomyolysis 1
• Disseminated intravascular coagulopathy develops as a consequence of extreme temperature elevation 1

Neurological and Multi-Organ Effects

• Central nervous system lesions have been documented in fatal cases of hyperthermia, with hemorrhages potentially contributing directly to death 3
• Liver, kidney, heart, adrenal, testis, and bone marrow all demonstrate important pathological lesions in severe hyperthermia cases 3
• Hyperthermia triggers increased metabolic demands that worsen neurological outcomes, particularly when combined with other metabolic stressors 4

Tissue-Specific Pathology

• Hemorrhagic diathesis affects multiple tissues universally in severe cases 3
• Localized hyperthermia can cause damage to skin, skeletal muscle, adipose tissue, liver, small intestine, brain, kidney, urinary bladder, prostate, and cartilage 3

Critical Timing Considerations

• Delayed complications can occur, with recrudescence of malignant hyperthermia reported up to 14 hours after initial control 1
• The speed of progression tends to be more rapid when reactions occur soon after trigger exposure 1
• Irreversible stage is heralded by onset of generalized muscle rigidity, even in the presence of neuromuscular blockade 1

Mortality and Morbidity

• Despite dantrolene availability, mortality remains approximately 4% in the UK, emphasizing that treatment may be unsuccessful unless implemented early 1, 2
• Delay in treatment is directly associated with increased mortality and severity of complications 1
• The condition can rapidly progress to irreversible injury or death once the metabolic cascade is triggered 5