hypothermia

what is this condition?

prolonged coolling (without freezing) excaerbated by moisture

results in peripheral nerve damage

initital exam: macerated (not the same pruning), pale, mottled, anesthetic, may be pulseless

after rewarming: extreme pain and hyperemic

trench foot

treat by elevation, dry loose dressing, and late debridement

What is the condition?

exposure to intermittent long-term damo non-freezing conditions

early: paresthesia, dysesthesi, and anesthesia

12-24hrs: pruritis, erythema, edema, cyanosis, nodules, and vesicles/ulcerations

rewarming may result in the formation of blue nodules

Chilblains (pernio)

treatment: supportive

What is the condition?

long-term exposure to above-freezing temperatures resulting in necrosis of subQ fat

common in equestrian riders (dimpled appearance)

panniculitis

what condition?

cold hives

mediated by histamines, anaphylaxis is rare

tx: antihistamines, leukotriene inhibs, epi

cold urticaria

When the skin temperature reaches less then 0C (does not occur if the ambient temp is above freezing)

upon thawing: arachidonic acid cascade → thrombosis → necrosis and dry gangrene

frostbite

What are the 4 mainstays of frostbite treatment?

• rapid rewarming but only after there is not risk of re-freezing

• immersion in or application of warm between 37C-39C

• opioid analgesia

• tetanus immunization if needed because frostbite is tetanus prone

are these controversial or nonconversial treatments?

ruptured clear blisters being debrided and if they are hemorrhagic leave them alone

noncontroversial

(controversial are debriding unruptured blisters, systemic antibiotics, topical, etc.)

True or false: surgery should take place immediately to remove necrosed skin to prevent further damage or infection

false; because you don’t know what tissue can be salvaged or not

What is considered hypothermia?

core temperature is <35C

Distinguish between primary and secondary hypothermia

primary: caused by cold environment

sencondary: caused by medical illness

What are some of the causes of secondary hypothermia? (there are several, just name a few and get the idea)

burns, blood transfusions, impaired shivering (malnutrition, very old or young, exhaustion, etc), medications, sepsis, metobolic and endrocrine d/o, shock, trauma with blood loss, etc.

Shivering is crucial to raising body temp. What are some things that can suppress shivering?

medications, exhaustion, warming devices, a core temperture drop below critical level (31C)

What are some physiologic responses to cold? (4)

• increased muscle tone and shivering

• peripheral vasoconstriction

• cold diuresis (pee when cold)

• CNS chagnes (impaired judgement, ataxia, EEG arrest, fixed and dilated pupils, etc.)

Explain paradoxical undressing when freezing?

this happens once your catecholamine stores are depleted because you have been vasoconstricted in the preiphery which is caused by catecholamines, but once they are depleted then you et a rush of blood to periphery (vasodilation) and you get very hot and undress

What are some cardiac changes from hypothermia?

• slow atrial fibrillation (bradycardic)

• osborn or J wave

• prolonged QT interval

• myocardial irritability

What are the metabolic responses to hypothermia?

• increase in metabolic rate

• as it continues to drop, dimunition of metabolism

• rhabdo

• speudo rigor mortis

• coagulopathy and platelet dynsfuntion (hypo and hypercoag)

What lab is essential for hypothermia?

glucose

management of hypothermia depends on ___ whcih is measured how?

core temperature (heart)

thermistor in the lower esophagus

How to manage stage 1 (35-32C conscious and shivering)

warm environment and dry clothes

no hot baths

warm sweet drinks

How to manage stage 2 (32-28C) impaired consciouness ± shivering?

• active external heating

• minimally invasive rewarming techniques

• monitor core temp

• NPO (impaired consciousness)

• full-body insulation, horizontal position, immobilization

How to manage stage 3; less then 28C, unconscious, BP or pulse still present

• no CPR

• all stage 2 management

• keep NPO

• ECMO (extracoporeal membrane oxygenation) or CPB (cardio-pulmonary bypass)

How to manage stage 4; may occur <32 but usually occurs <28; no BP or pulse and no forward blood flow

• CPR

• epi and defibrillation

• airway management

• transport to ECMO/CPB

• active external with minimally invasive rewarming during transport

• do NOT apply heat to head

What is afterdrop?

as the periphery warms and vasodilates, warmer core blood is shunted to the periphery making the core colder

studies have shown this to be minimal

What are some poor prognostic signs which support the decision to terminate resiscitative efforts? (7, just get the idea)

• serum K+ >12

• rewarmed >32C with still no forward blood flow (no forward blood flow also means pressors won’t work)

• DNR order

• mortal injury

• prior normothermic arrest

• drowning

• frozen solid