Heat Production and Loss Environmental Emergencies Messing with Mother Nature Heat Production Basal Metabolism processes in the body that generate heat through nominal functions Activity, fever, metabolic imbalances Heat Transfer Conduction Convection Evaporation Breathing Heat Regulation Brain Controls from where? Many regulatory mechanisms Breathing Cardiovascular Redirect blood flow to conserve or reduce heat Increase / decrease rate of flow as needed Skin Utilizes both radiation and convection to reduce heat Body Temperature Ranges Tightly regulated operating range 98.6ºF core temp is average your mileage may vary Oral Temp usually 1º less than core, Axillary temp usually 2º less than core Many factors put one at risk for reduced regulatory ability Age, Mobility, Alcohol, Chronic Exposure, Health, recent regulatory compromise Increases in temp can speed up metabolism to a point Decreases in temp slow metabolism to the end Your Patient: 41 year-old male at campground Lost in woods all night 28 degrees). Found this morning by searchers Lethargic, disoriented Airway clear Breathing slow/shallow Slow, weak pulse; pale, cold skin No obviuos bleeding, deformity, disability Focused Assessment: Clothing is damp, muddy Abrasion and scratches on arms and hands Fingers are pale and appear numb with little movement Vitals: HR 54 r/w BP 98/40 RR 12 shallow oral temp 89 degrees
HypOthermia A loss of the ability to maintain temperature Results in a slowing of the metabolic processes Mild 93ºF and above Moderate 86ºF to 93ºF Severe =< 86ºF Circulatory system redirects blood to core to maintain function of organs as long as possible HypOthermia S/S Cool extremities may be pale = lack of blood flow, or cyanotic = poorly oxygenated/circulated blood Shivering initially lack of shivering may be due to inability to continue, not warmth Decrease in respiratory drive, pulse and BP Altered Mentation incl. Hallucinations, coma, death Cardiac dysrhythmias V-FIB This is a continuum once it begins, it will continue downward until heat loss is stopped because the body has lost the ability to stop it on it s own HypOthermia - Tx In general, we do NOT warm severely hypothermic Pts For MILD hypothermia (normal LOC): Oxygen as needed, handle gently and stop heat loss. Active rewarming with heat packs to neck, groin and axillary is ok at this point. For severe hypothermia (altered LOC): Limit oxygen for definite need only, Handle VERY gently and prevent further heat loss do NOT rewarm unless help is greatly delayed. Rewarming Dangers Dangers: Rewarming shock the body vasodilates to send blood to the extremities to be rewarmed a vasodilatory type of shock BP and perfusion drop dramatically! V-FIB as blood flow is suddenly restarted to the extremities, poorly circulated / cold blood from the extremities is sent back to the heart Notes on HypOthermia It is the loss of the body s ability to maintain temp not necessarily the exposure to extreme cold can occur in mildly cool environments - 70ºF room with limited mobility Requires energy blood sugar to generate body heat and body heat drops rapidly as sugar is used up Blake s Rules to Live By: HypOthermia Hypothermia and Hypoglycemia go hand in hand always consider hypoglycemia in hypothermic Pts and consider hypothermia in hypoglycemic Pts Stroke / Brain Attack Pts often suffer from hypothermia / hypoglycemia due to lack of mobility / generation of heat and dwindling glucose
Localized Cold Injuries Frost Bite Frostbite as the blood is redirected (shunted) to protect the core, the extremities encounter reduced warming Frostbite occurs as fluid in tissues actually freezes ice crystals may form, actually destroying cells. Tissue ranges from numb/sore and pale, to blue or white and firm as frostbite progresses Frostbite Txs Prevent further heat loss do NOT rewarm! Treat and bandage as a burn Keep the Pt off the extremity and do NOT massage the tissue Rewarming in the field is only for extreme circumstances: Rewarm the entire part at once in hot (104ºF) water Do NOT allow to refreeze!!!!! Localized Cold Emergencies Immersion Foot also known as trench foot in wartime Results from reduced circulation from cold environment and moisture Extremities become swollen and cool to the touch progressing to hot, red and very painful and swollen Treat as a burn and keep warm and dry Heat Emergencies Your patient: 25 year-old landscaper C/o severe weakness and leg cramps Alert, weak Airway clear Breathing rapid, labored, adequate Rapid strong pulse, flushed/sweaty/warm skin No obvious hemorrhages/deformities Focused Assessment?
Heat Emergencies the other side of the coin The body produces heat as a part of metabolism enough heat to roast itself if it can t dissipate some heat Most of this is accomplished through respiration and radiation off the skin As more cooling is needed More blood flow is sent to the surface of the skin to increase radiation Sweat glands make the skin moist utilizing convection/evaporation for cooling Heat Emergencies The body works very hard to maintain core temperature but it can be overcome If the body gets low on fluids, cooling ability is reduced The temp. and humidity can combine to reduce or prevent evaporation, which will limit the effectiveness of sweating As body temp. rises, systems begin to shut down due to altered metabolic function Heat Cramps A minor heat emergency Result from an electrolyte imbalance and lactic acid build up inside muscles Manifest as severe burning or cramping sensation in muscles during or after heavy work in a hot or humid environment Stopping activity, moving to a cool environment and drinking MILD electrolyte solutions will usually relieve the pain General Tx notes: Oral Electrolyte solutions O.k. for non-systemic problems i.e. Heat Cramps Should be MILDLY hypertonic (electrolyte) NEVER administer full strength sports drinks to overheated individuals mix them 50/50 with water Once someone has suffered from a heat related problem, they will be more susceptible to heat illnesses for several days or more Heat Exhaustion Similar to Compensated Shock in the fact that the body is fighting a problem, and currently winning, or at least holding it s own What we see are mostly the effect s of the body s fight Cool, moist skin, rapid heart rate and breathing (not so much shock signs, as cooling attempts) Possibly some of the effects the fight is having on the body as well Dizziness, weakness, nausea, orthostatic hypotension (largely resulting from the amounts of fluid used to fight the problem) NORMAL Level Of Consciousness Fainting is possible, but normal LOC returns quickly Heat Exhaustion Tx Recognize the problem NOW, while the body is still effective at dealing with it this way the body can help you treat it Move the Pt to a cool environment Cool with cool, wet towels, fans, etc. DO NOT CAUSE SHIVERING Allow to drink MILD electrolyte fluids or water if the Pt is not too nauseated and can protect their own airway Pts can usually be considered Delayed
Heat Stroke Results when the body has lost the ability to control/effectively reduce the core temp. to survivable levels Is primarily defined by Level Of Consciousness Skin may be red, hot and dry or may still be sweaty Pulse becomes more rapid, respirations become rapid and deep Level Of Consciousness is decreased and will progress to coma and death without immediate intervention Other signs of severe dehydration might be present Furrowed tongue, dull/lackluster eyes, hypotension, poor skin turgor Heat Stroke Tx Move to a cool environment and remove clothing Aggressive cooling with water mist/fans, or icepacks to the neck, armpits and groin DO NOT CAUSE SHIVERING!!! Oxygen may be helpful at lowering temp also Monitor core temp. yes, that means rectal temps if possible Rapid transport these Pts are in Immediate danger Heat Exhaustion/Heat Stroke Heat exhaustion and Heat stroke are two ends of the same line a progression, just like shock is. We classify someone as having heat stroke when their body core temp becomes so high that it effects brain function (a failure of the cooling ability usually around 105-106ºF) The presence of sweating indicates an attempt at cooling, not successful cooling and therefore is NOT an indication of severity Blake s Rules to Live by: Environmental ALWAYS consider your Pt s environment Watch for trauma Pts who are: Losing body heat due to being stripped shock Tx/prevention involves maintaining body heat Losing body heat due to immobility on cold surfaces Being roasted due to immobility on hot surfaces ANY Pt who can t move around on their own may have been drastically effected by their environment