Heat and Cold Emergencies

1. Heat and Cold Emergencies Jonathan Rochlin, MD February 22, 2010

2. Outline • Physiology primer • Local injuries due to the cold • Hypothermia • Hyperthermia • Take home points

3. Objectives • Learn about the wide range of local cold injuries • Learn the dos and don’ts of frostbite treatment • Understand the management of hypothermia • Understand the spectrum of hyperthermic disorders and their treatments • Understand how to prevent hyperthermia in the young athlete

4. Physiology primer • Local injuries due to the cold • Hypothermia • Hyperthermia • Take home points

5. Physiology Primer • Core temperature maintained within 0.6°C (1°F) • Balance between heat production and heat loss • Heat production: • Basal cellular metabolism • Muscle activity • Heat loss: • Conduction • Convection • Evaporation • Radiation • Behavioral control

6. Physiology primer • Local injuries due to the cold • Hypothermia • Hyperthermia • Take home points

7. Local Injuries Due To The Cold • Frostnip • Frostbite

8. Local Injuries Due To The Cold • Frostnip: • Milder form of freezing local cold injury • Symptoms: Pain, pallor • Prognosis: Resolves with rewarming

9. Local Injuries Due To The Cold – Frostbite • Frostbite: • The most severe local cold injury • Who is at risk? • Those exposed to cold environments or materials • Comorbidities • Alcohol intoxication • Inappropriate clothing

10. Local Injuries Due To The Cold – Frostbite • Sites most often affected: • Head: • Ears • Nose • Cheeks • Chin • Fingers • Toes

11. Local Injuries Due To The Cold – Frostbite • Pathophysiology: • Immediate damage: ice crystals  cell death • Gradual damage: inflammatory process  tissue ischemia

12. Local Injuries Due To The Cold – Frostbite • Classification:

13. Local Injuries Due To The Cold – Frostbite

14. Local Injuries Due To The Cold – Frostbite

15. Local Injuries Due To The Cold – Frostbite • Symptoms and appearance: • Cold • Numb • White, pale or gray • Hard or waxy • Edema and erythema • Blisters • Eschars

16. Local Injuries Due To The Cold – Frostbite • Treatment – rewarming: • Dos: • As soon as possible • Immerse in warm water (about 40°C) • Until pink (about 20-30 minutes) • Increase body temperature • Don’ts: • Use hot water • Dry heat, stoves or fire • Rub or massage • Don’t rewarm if the part will be refrozen

17. Local Injuries Due To The Cold – Frostbite • Treatment – wound care: • Goal: prevent infection • Don’t pop blisters • Let the area dry • Apply bulky dressing: • Sterile technique • Non-stick first layer • Separate digits • Non-occlusive • Watch for pressure spots

18. Local Injuries Due To The Cold – Frostbite • Treatment – other interventions: • Dos: • Cardiac monitor • Warmed fluids • Elevate • IV narcotics • Ibuprofen • Tetanus prophylaxis • IV antibiotics (only for signs of infection) • X-ray • Consult surgery

19. Local Injuries Due To The Cold – Frostbite • Treatment – other interventions: • Don’ts: • Debride or amputate immediately • Walk on frostbitten feet • Use vasoconstrictive agents

20. Local Injuries Due To The Cold – Frostbite • Complications: • Short-term • Long-term • Prognosis: • Must wait until demarcation • Disease of morbidity, not mortality

21. Physiology primer • Local injuries due to the cold • Hypothermia • Hyperthermia • Take home points

22. Hypothermia • Epidemiology: • About 700 deaths per year in the U.S. • Mortality rate ~ 40% • It can happen anywhere

23. Hypothermia • Definition: • Core temperature ≤ 35°C (≤ 95°F) • Mild hypothermia: 32-35°C (89.6-95°F) • Moderate hypothermia: 28-32°C (82.4-89.6°F) • Severe hypothermia: < 28°C (< 82.4°F)

24. Hypothermia • Physiologic response to cold: • Heat production increased: • Metabolism increased • Muscle tone increased  shivering • Heat loss decreased: • Sweating stopped • Vasoconstriction occurs

25. Hypothermia • Populations most at risk: • Neonates • Elderly • Homeless • But it can happen to anyone • Risk factors: • Physical disability • Psychiatric disorders • Medications and drugs • Vehicular breakdown

26. Hypothermia • Causes: • Exposure to cold water or air • Sepsis • Burns • CNS dysfunction • Endocrinopathies • Metabolic disorders • Neuromuscular diseases • Hypoglycemia • Iatrogenic

27. Hypothermia • Clinical manifestations: • General appearance: pale, gray or cyanotic and cold

28. Hypothermia • Clinical manifestations – CNS: • Decreased consciousness is most consistent finding • Progressive decline from confusion to coma • Decrease in DTRs • Dilated pupils • EEG changes

29. Hypothermia • Clinical manifestations – respiratory: • Early findings: • Tachypnea • Bronchorrhea  airway obstruction/aspiration • Late findings: • Hypoventilation • Pulmonary edema • Apnea

30. Hypothermia • Clinical manifestations – cardiovascular: • Early findings: • Increased BP • Tachycardia • Late findings: • Bradycardia • Hypotension • Conduction abnormalities: • Prolonged intervals • V fib • Asystole

31. Hypothermia • Clinical manifestations – cardiovascular: • J wave

32. Hypothermia • Clinical manifestations – metabolic: • Decreased metabolic rate • Respiratory and metabolic acidosis • Hyper- or hypoglycemia

33. Hypothermia • Clinical manifestations – renal: • Early findings: • “Cold diuresis” • Late findings: • Decreased renal perfusion • Oliguria • Hyperkalemia • Edema

34. Hypothermia • Clinical manifestations – hematologic: • Hematocrit increases • WBC and platelet counts fall • DIC

35. Hypothermia • Clinical manifestations – GI: • Ileus • Hepatic dysfunction • Pancreatitis

36. Hypothermia • Clinical manifestations – musculoskeletal: • Early findings: • Shivering • Late findings: • No shivering • Pseudo rigor mortis

37. Hypothermia • Severe hypothermia mimics death • But the patient may be alive • You’re not dead until you’re warm and dead • Resuscitate until temperature is 32-35°C (90-95°F)

38. Hypothermia • Initial resuscitation: • Airway, breathing (A/B): • Supplemental oxygen • Intubate early, and gently • Ventilate at ½ normal minute ventilation

39. Hypothermia • Initial resuscitation: • Circulation (C) – rate and rhythm: • Is there an organized rhythm? • PALS/ACLS algorithm: • V fib: • Defibrillation • Bretylium • Asystole: • Pharmacotherapy • Rarely effective • CPR • Try again after temperature rises • Handle gently • Correcting temperature can correct rhythm

40. Hypothermia • Initial resuscitation: • Circulation (C) – blood pressure support: • Obtain IV access • Warmed fluids • Dopamine • Watch for rebound hypotension

41. Hypothermia • Initial resuscitation: • Disability (D) • Exposure (E)

42. Hypothermia • Monitoring: • Core temperature – low reading thermometer • Cardiac monitor • Place pulse ox probe on ear or forehead • Foley

43. Hypothermia • Laboratory evaluation: • CBC • BMP • Amylase • pt, ptt, INR • ABG • BCx • UDS and alcohol level • EKG • CXR • Treat abnormalities accordingly • Frequent reassessments

44. Hypothermia • Rewarming: • Immediately • Passive external rewarming: • For mild hypothermia (> 32°C or 89.6°F) • Remove wet clothing • Place under blankets • The patient rewarms himself

45. Hypothermia • Rewarming – active external rewarming: • For moderate to severe hypothermia (< 32°C or 89.6°F) • Place patient is warm room with overhead warmers • Warm blankets and clothes • Heating pads • Forced warm air

46. Hypothermia • Rewarming – active external rewarming: • Complications: • Core temperature afterdrop • Rewarm trunk and head first • Keep patient still • Body surface burns

47. Hypothermia • Rewarming – active internal rewarming: • Pleural irrigation • Peritoneal irrigation • Bladder irrigation • Hemodialysis or CVVH • Cardiopulmonary bypass • Forced air rewarming • Complications: • Hyperthermia

48. Hypothermia • Why isn’t the patient getting warmer? • Hypoglycemic? • Septic? • Adrenocortical insufficiency? • Hypothyroidism?

49. Hypothermia • Continued monitoring • Transfer

50. Physiology primer • Local injuries due to the cold • Hypothermia • Hyperthermia • Take home points