What are the effects of heat exposure on patients for Emergency Medical Services (EMS)?

From the Guidelines

Emergency Medical Services (EMS) providers should immediately recognize and treat heat-related illnesses using a systematic approach, prioritizing rapid cooling for heat stroke patients using ice packs, cold water immersion, and cold IV fluids, as recommended by the most recent guidelines 1.

Key Considerations for Heat-Related Illnesses

• Heat exhaustion: move the patient to a cool environment, remove excess clothing, apply cool wet towels, and provide oral rehydration with electrolyte solutions if the patient is alert.
• Heat stroke: rapidly cool the patient using ice packs to the groin, axillae, and neck, cold water immersion if available, and cold IV fluids (normal saline at 4°C, 15-30 mL/kg), as this is a true medical emergency.
• Core temperature should be monitored continuously with a rectal thermometer when possible, as rectal temperature has been demonstrated as the most accurate method for measuring body temperature 1.
• Benzodiazepines such as midazolam (2-5 mg IV) may be needed for shivering or seizures.
• Patients with altered mental status, core temperature above 104°F (40°C), or unstable vital signs require immediate transport to an emergency department.

Prevention and Education

• Prevention education is crucial, advising about adequate hydration (approximately 1 liter per hour during extreme heat exposure), wearing light clothing, and limiting activity during peak heat hours.
• Heat illness occurs when the body's thermoregulatory mechanisms fail, with the elderly, very young, those with chronic medical conditions, and individuals taking certain medications (diuretics, anticholinergics, antipsychotics) at highest risk.

Additional Recommendations

• Emergency action plans with clearly defined written protocols should be developed and in place ahead of time, including immediate activation of EMS communication for any patient who collapses or exhibits moderate or severe central nervous system dysfunction or encephalopathy during or after practice, competition, or other physical activity in the heat 1.
• On-site whole-body rapid cooling using proven techniques should be initiated without delay for patients with suspected heat stroke, with a goal of cooling the patient to a temperature below 38.9°C (102°F) within 30 minutes of collapse 1.

From the Research

Heat Exposure Questions for EMS

• Heat-related illnesses comprise a spectrum of syndromes resulting from disruption of thermoregulation in people exposed to high environmental heat, with symptoms ranging from heat edema and exercise-associated muscle cramps to exercise-associated collapse, heat exhaustion, and life-threatening heat stroke 2.
• Athletes, outdoor laborers, and military personnel are at greatest risk of heat-related illness, and several intrinsic and extrinsic factors increase the risk, including medical conditions, environmental factors, medication use, and inadequate acclimatization 2.
• Management of heat-related illness includes:
  • Supportive measures such as hydration and moving the patient to a cool place for milder forms of heat-related illness 3.
  • Mild cooling, rest, and hydration for heat exhaustion 2.
  • Ice water or cold water immersion for heat stroke, which is a medical emergency 2, 4.
• Cooling techniques for heat stroke and exertional hyperthermia include:
  • Water immersion, which can rapidly reduce core body temperature 4.
  • Applying ice packs to the head, neck, axilla, and groin as an alternative to cold water immersion 3.
• Prevention of heat-related illnesses is crucial, and guidelines for clinicians and healthcare professionals include:
  • Recognizing the warning signs of heat-related illnesses 5.
  • Taking appropriate protective measures such as acclimatization, adequate hydration, and avoidance of activities during extreme heat 2, 5.
• Patients with heat stroke or severe heat-related illness should refrain from physical activity for at least seven days after release from medical care, then gradually begin activity over two to four weeks 2.