Sohil Pothiawala FAMS (EM), MRCSEd (A&E), M.Med (EM), MBBS Consultant Dept. of Emergency Medicine Singapore General Hospital

Transcription

1 Heat Emergencies: is it too hot to handle? Sohil Pothiawala FAMS (EM), MRCSEd (A&E), M.Med (EM), MBBS Consultant Dept. of Emergency Medicine Singapore General Hospital

2

3

4

5

6

7

8 Epidemiology 4,000 heat related deaths yearly 80% of the fatalities are elderly Occurs in 5 per million over age 85 compared to 1 per million in the 5-44 age group 2 nd leading cause of death among young athletes Very young (<4yo) also at increased risk

9 Causes of Heat Illness (c) 2004 The McGraw-Hill Companies, Inc. All rights reserved. Heat stress Body Heat + Environment Heat > Heat Lost = Heat stress

10 Factors Affecting Body Temperature Regulation The three main factors Air temperature Humidity Wind Others Clothing Breaks from exposure to extreme temperature Water intake Intensity of activity

11 Pathophysiology of Thermoregulation When the body gets too hot When the body gets too cold Anterior hypothalamus ANS stimulation increases vasomotor tone and cutaneous blood flow Parasympathetic stimulation Sweating Dehydration can predispose individual to heat injury Acclimatization Results from repeated exposure (exercise)

12 How it Happens sun work Blood vessels dilate bring blood to surface Body tries to release heat by conduction, convection, radiation body heat rises Heart pumps faster Sweat: releases heat by evaporation

13 Heat you generate working or fighting an infection It s a Fine Balance WARMING Heat Production COOLING Heat Loss Heat you lose by radiating sweating, breathing & evaporating Source: Richard P. Sandor Heat Illness: On-Site Diagnosis and Cooling, The Physician and Sportsmedicine, June 1997.

14 Heat-Related Emergencies The spectrum: Heat Rash Heat Edema Heat Tetany Heat cramps Heat exhaustion Heat stroke R. M. Place

15

16 Heat Rash - Prickly Heat Cause: Clogged sweat glands from damp skin and clothing from unevaporated sweat Symptoms: Red itchy skin folds or where clothing rubs skin Consequences: Bacterial infections, chronic dermatitis Rx: cleanse and dry skin; apply soothing lotion to inflamed area

17 Heat Edema Due to cutaneous vasodilatation and orthostatic pooling of interstitial fluid in extremities Most often found in elderly, non-acclimated travelers Usually self limiting Rx is limb elevation, compression stockings Heat Tetany Hyperventilation resulting in respiratory alkalosis, paresthesia, and carpo-pedal spasm Usually associated with short periods of intense heat stress Rx includes removal from heat and decreasing respirations

18 Heat Cramps Painful spasms of skeletal muscles, usually legs Usually occurs during or after exercise Unconditioned, non acclimated individuals at high risk Pathogenesis: Deficiency of Na, K+, and H 2 O at cellular level causing temporary fluid electrolyte imbalance Symptoms: Painful muscle spasms in the arms, legs, and abdomen Rx Move to a shaded place Rest Lightly stretch the affected muscles Replenish fluids/electrolyte drinks Apply moist towels to cramped muscles

19 Heat Syncope Cause: Blood pooling in legs Symptoms: Brief loss of consciousness. Consequences: Injury from falling Rx: - Elevate legs - wet cloth + fan - Refer for medical evaluation

20 Heat Exhaustion Known heat exposure Core body temperature C The signals Cold, clammy, pale or flushed skin Tachycardia Headache, nausea, dizziness Weakness, exhaustion Heavy sweating Syncope In its early stage can usually be reversed with prompt care Rx includes move to cool place, rest, fluid volume and electrolyte (Na) replacement Usually discharged after few hours

21 Heat Stroke Most severe heatrelated illness A medical emergency Breakdown of thermoregulation

22 Heat Stroke Cause: - Temperature regulation has failed - No sweat available for cooling. Symptoms: same as heat exhaustion + Very high body temperature (> 104 F) Hot, dry, reddish skin; dry mucosa Central nervous system: irrational behavior, incoherent, confused, psychosis, seizure, coma Rapid, strong pulse Triad Temp > C ( ) CNS dysfunction (delirium, seizures, coma) Hot skin, sweating vs anhidrosis Anyone with hyperpyrexia and AMS is considered heatstroke until proven otherwise Consequences: - Organ failure, Death

23 Heat Stroke vs. Heat Exhaustion HEAT STROKE 1. Dry, hot skin 2.Very high body temperature 3. Confusion HEAT EXHAUSTION 1. Moist clammy skin 2. Normal or subnormal body temperature

24 Classic (nonexertional) Types - In elderly with chronic medical conditions, poor housing conditions - Anhidrosis - Normoglycemia - oliguria - Mild acidosis and coagulopathy - Mild CPK elevation Exertional - In young, healthy individuals engaged in heavy exercise - Diaphoresis - Hypoglycemia - Acute renal failure - Marked acidosis and DIC - Rhabdomyolysis

25 Physical Findings Hyperthermia AMS or seizures Anhidrosis vs moist skin Flushing (cutaneous vasodilation) Tachypnoea Crepitations due to non-cardiogenic pulmonary edema Excessive bleeding due to DIC

26 Diagnostic evaluation History and physical examination Temperature and vitals ECG FBC, urea and electrolytes LFTs PT/PTT CK and myoglobin Urine for myoglobinuria CXR

27 Treatment of Heat Stroke ABC s, high flow O 2 IV access and volume replacement with isotonic NS Temperature monitoring (rectal vs esophageal) Cooling Techniques - Evaporative cooling/body cooling units - Ice water immersion - Ice packs to axillae and groin - Cool blankets - Cool IV fluids - Gastric lavage - Peritoneal lavage (unproven efficacy in humans) - Cardiopulmonary bypass Seizures treated with IV benzodiazepines

28 Evaporative Cooling Safe and effective in both exertional and classic heat stroke Non-invasive Easily performed Does not interfere with patient access and monitoring Associated with decreased morbidity and mortality

29 Complications of Heat Stroke Non-cardiogenic pulmonary edema, ARDS Seizures Hepatic injury (thermal) Acute Kidney injury rhabdomyolysis, myoglobinuria, and renal failure Hematological insult - DIC - Micro-hemorrhages - Thrombocytopenia - Increased platelet aggregation (thermal) Fluid/Electrolyte disturbances Cardiovascular collapse

30 Pearls Patients with exertional heat stroke are commonly diaphoretic No role for antipyretics like paracetamol or aspirin Heatstroke can cause features resembling pulmonary edema (elevated CVP and right cardiac dilation), yet requires vigorous crystalloid resuscitation Wet sheets over a patient, without good air flow, will tend to increase temperature and should be avoided Do not let cooling in the field delay your transport. Cool patient if possible while en-route

31 Too hot to handle???? Chill!! Its Over.

32 THANK YOU