Cold Injuries: An Update on Hypothermia and Frostbite

Transcription

1 Cold Injuries: An Update on Hypothermia and Frostbite

2 HYPOTHERMIA

3 Definitions Shell = skin, subcutaneous tissues and extremities; temperature of the shell varies according to environment Core = brain, heart, deep vessels and organs; are maintained at a steady temperature

4 Definitions Continued: Core Body Temperature Measured by rectal, esophageal, or tympanic thermometer Oral temperatures read 1 degree less than rectal

5 Definitions Continued: Hypothermia -- a cooling of the core body temperature to less than 35oC (95oF): Mild: oC (90 95oF) Moderate: oC (82-90oF) Severe: less than 26.6oC (80oF)

6 Epidemiology Between 79 98: 13,970 deaths in US 49% of the decedents were 65 or older Urban settings still account for the majority of cases

7 Classifications Acute duration less than an hour Sudden rapid cooling as in an injured alpine climber; without lowered O2 content in air, cooling causes decreased O2 consumption, slowed metabolism, and decreased organ ischemia

8 Classifications Subacute duration 1-24 hours Blood sugar reserves are used; fairly abrupt onset of cooling then follows, i.e., uninjured alpinist stranded in the mountains.

9 Classifications Chronic duration greater than 24 hours Seen in urban winter environment; often with pre-existing illness, i.e., psychiatric disorder, or drug/alcohol use Onset slow

10 Mortality Mortality rates are less than 10% for hypothermia alone! Mortality rates are 75-90% for hypothermia accompanied by an underlying illness!

11 Hypothermia Risk Factors Elderly Homeless Mentally ill or incapacitated Outdoor work (exposure) Trauma (traumatic brain injury, cord transection) Cardiovascular disease

12 Hypothermia Risk Factors Excessive alcohol Hypothyroidism Infections (sepsis) Exhaustion, heavy exertion

13 Hypothermia Risk Factors Burns Poor nutrition Inadequate clothing Inadequate housing or heating Drugs: sedatives, narcotics

14 General Management Prevent further heat loss Monitor core temperature & pulse Re-warm patients with core temperature of < 34oC (93oF) [passive or active external] Careful transportation to hospital

15 Passive Rewarming For patients with mild hypothermia who are capable of generating body heat, i.e., previously healthy individuals Blankets Warm room

16 Active External Rewarming Person to person heat transfer body to body" Warm water immersion -- hot tub Radiant heat -- heat lamp, electric blanket Warm packs -- hot water bottles Forced hot air electric heater with fan

17 Which Rewarming Technique? 30 C to 34 C: Passive rewarming (completely dry off), apply blankets Active external rewarming hot water bottles to trunk areas electric heater with fan Warm IV solution by EMS personnel

18 Recommendations Continued: Obtain rectal body temperature in field (but don t delay transport) Prevent further heat loss Treat gently Transport promptly Start warm IV with normal saline (EMS)

19 Hypothermia Summary Hypothermia -- a cooling of the core body temperature to less than 35oC (95oF) Multiple systems are affected Cold is initially protectant of tissues, especially the brain Primary hypothermia death due an eventual failure of myocardial conduction - asystole

20 Hypothermia Summary Prevent further heat loss Monitor core temperature & pulse Re-warm patients with core temperature of < 34oC (93oF) [passive or active external] Carefully transport to hospital

21 Remember A patient is not dead until they are warm dead!

22 Snowy Mountains and Fog In Valley

23 Frostbite

24 Frostbite Actual freezing of a body part; occurs when the temperature of the body part falls below the freezing point of body tissue (about minus 4oC or 25oF) Irreversible tissue damage depends on the extent and duration of freezing at the tissue level

25 Frostnip Cold-induced area of superficial blood-vessel constriction Mild tingling or pain followed by numbness Gray or yellowish patch of exposed skin After warming, affected part is tender, pink, warm, and may be shiny or slightly swollen Complete recovery in 1-2 weeks

26 Frostbite Post-Rewarming Classification Difficult to predict the severity of injury when frostbite is first seen Severity established only after re-warming has occurred 3-4 days usually needed to know if superficial or deep

27 Superficial Only the skin has been frozen Large blisters filled with clear or yellow fluid develop in about 12 hours Erythema with rewarming; persistent increased skin sensitivity

28 Deep Complete anesthesia (lack of sensation) Hemorrhagic (blood-filled) blisters Edema proximal to frostbite in 5-7 days

29 Deep -- Progressive Completely through dermis Subcutaneous tissue, muscle, bone Causes eventual mummification

30 Emergency Care Immediate, rapid rewarming: immerse in 40 to 42oC (104 to108of) water-bath, minutes, with active motion of joints AVOID REFREEZING Maintain hydration Appropriate wound care: apply a dry, sterile, soft dressing Elevate frostbitten parts

31 Emergency Care Immediate, rapid rewarming: immerse in 40 to 42oC (104 to108of) water-bath, minutes, with active motion of joints AVOID REFREEZING Maintain hydration Appropriate wound care: apply a dry, sterile, soft dressing Elevate frostbitten parts

32 Prognosis 3-4 days needed to know if deep or superficial Amputations traditionally delayed until dry necrosis occurs 30 + days for appearance of cut line of demarcation for amputation ( Frostbite in January, amputation in July )

33 Consequences Amputation Sensitivity problems (pain, cold sensitivity) Finger joint pain, stiffness and flexion contractures Late: osteoporosis and early arthritis from cartilage injuries

34 Beck Weathers Mount Everest 1996