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Accidental Hypothermia Laura Klouda, MD. Intro Definition Definition –Unintentional drop in body temperature of about 2°C from “normal” (normal = 37.2-37.7°)

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Presentation on theme: "Accidental Hypothermia Laura Klouda, MD. Intro Definition Definition –Unintentional drop in body temperature of about 2°C from “normal” (normal = 37.2-37.7°)"— Presentation transcript:

1 Accidental Hypothermia Laura Klouda, MD

2 Intro Definition Definition –Unintentional drop in body temperature of about 2°C from “normal” (normal = 37.2-37.7°) Contributing factors/stressors Contributing factors/stressors –Extremes of age –Nutritional status/dehydration –Pre-existing health conditions –Intoxicants/medications that potentially decrease thermostability –Exposure type –Fatigue and lack of sleep –Trauma –Wet clothing Treatment depends on duration and severity of hypothermia and contributing factors/stressors Treatment depends on duration and severity of hypothermia and contributing factors/stressors

3 Nervous system effects Shivering (more effective at producing heat than voluntary muscle contraction) Shivering (more effective at producing heat than voluntary muscle contraction) Memory loss Memory loss Impaired judgment Impaired judgment Decreased level of consciousness Decreased level of consciousness Slurring of speech Slurring of speech

4 Cardiovascular effects Bradycardia Bradycardia –Due to slowed pace-maker cell depolarization  refractory to atropine Decreased cardiac output Decreased cardiac output EKG changes EKG changes –Prolonged PR, QRS, and QTc –J (Osborn) waves Dysrhythmias Dysrhythmias All of these can be worsened during afterdrop All of these can be worsened during afterdrop –Afterdrop is a drop in core temp after the warming process has begun

5 Respiratory effects Initially tachypnea Initially tachypnea Bradypnea as hypothermia worsens Bradypnea as hypothermia worsens –Thus CO2 retention and respiratory acidosis Noncardiogenic pulmonary edema Noncardiogenic pulmonary edema Increased and thickened secretions Increased and thickened secretions

6 Renal effects Decreased blood flow to kidneys  decreased glomerular filtration rate  results in build up of nitrogenous waste products Decreased blood flow to kidneys  decreased glomerular filtration rate  results in build up of nitrogenous waste products An initial large diuresis results in hemoconcentration. Then followed by oligo/anuria. An initial large diuresis results in hemoconcentration. Then followed by oligo/anuria.

7 Effects on coagulation Bleeding Bleeding –Due to cold-induced hypercoagulability and thrombocytopenia –Appears similar to DIC (disseminated intravascular coagulation) Hyperviscosity of blood due to hemoconcentration from diuresis and also from stiffening of red blood cells Hyperviscosity of blood due to hemoconcentration from diuresis and also from stiffening of red blood cells

8 Physical exam findings HEENT HEENT –Mydriasis, decreased extraocular movements, facial edema and/or flushing, epistaxis and/or rhinorrhea Cardiovascular Cardiovascular –Initial tachycardia followed by bradycardia, dysrhythmia, jugular venous distension, hypotension Respiratory Respiratory –Initial tachypnea followed by bradypnea/apnea, increased adventitious lung sounds GI/GU GI/GU –Constipation, abdominal distension, emesis, polyuria to anuria Neuro Neuro –Decreased LOC, ataxia, amnesia, initial hyperreflexia followed by areflexia, mood/personality changes Skin/Musculoskeletal Skin/Musculoskeletal –Shivering, increased muscle tone, erythema, pallor, cyanosis, frostbite, edema

9 Pre-hospital management Basic principles: Basic principles: –Rescue and remove from cold exposure –Physical exam –Remove wet clothing, stabilize injuries, cover wounds –Body temperature IV fluids if possible Place bag under patient’s buttocks or in a compressor Place bag under patient’s buttocks or in a compressor Warm fluids by taping hand/feet warmers to fluid bag Warm fluids by taping hand/feet warmers to fluid bag –Limit rewarming to: Hot water bottles covered in stockings/mittens placed in patient’s axillae/groin/neck Hot water bottles covered in stockings/mittens placed in patient’s axillae/groin/neck –Be cautious not to burn the patient Heated insulation Heated insulation Inhalation of heated humidified oxygen Inhalation of heated humidified oxygen –Patient should remain horizontal –Insulate and wrap patient Sleeping bags, clothing, tents, etc. Sleeping bags, clothing, tents, etc. –Transport to hospital –Only consider surface re-warming if medical care is unavailable Body-body contact, warm objects, radiant heat Body-body contact, warm objects, radiant heat

10 Pre-hospital life support Avoid jostling or quick movements of comatose patients Avoid jostling or quick movements of comatose patients –They are extremely likely to go into ventricular fibrillation if jostled Primary objective = prevent further heat loss Primary objective = prevent further heat loss Never assume death when patient is still cold. “No one is dead until warm and dead” Never assume death when patient is still cold. “No one is dead until warm and dead” IV glucose, naloxone, and flumazenil IV glucose, naloxone, and flumazenil

11 Pre-hospital life support Rescue breathing may be difficult due to stiffened muscles Rescue breathing may be difficult due to stiffened muscles Common problem is overventilation causing hypocapnic ventricular instability Common problem is overventilation causing hypocapnic ventricular instability Indications for intubation are the same as for a normothermic patient Indications for intubation are the same as for a normothermic patient –Avoid overinflation of the cuff in freezing temperatures. The cuff will expand upon reaching warmer temps  can kink tube and/or damage trachea Palpate/auscultate pulses for a full minute before deciding if patient requires chest compressions Palpate/auscultate pulses for a full minute before deciding if patient requires chest compressions –Often bradycardic with low cardiac output –Unnecessary chest compressions  can cause ventricular fibrillation If cardiac monitor and defibrillator available: If cardiac monitor and defibrillator available: –Defibrillate if ventricular fibrillation or asystole –Pads generally don’t stick well to cold skin May need tincture of benzoin May need tincture of benzoin

12 Emergency Department Care IV/O2/Monitor IV/O2/Monitor Warmed IV normal saline Warmed IV normal saline Monitor vitals and confirm hypothermia Monitor vitals and confirm hypothermia –Doppler may be needed to obtain a pulse –Rectal thermometer inserted 15cm or esophageal temps are generally reliable Thermal stabilization Thermal stabilization –Heat via conduction/convection/radiation/respiration Maintain tissue oxygenation Maintain tissue oxygenation –CPR/rescue breathing Determine 1° vs 2° hypothermia Determine 1° vs 2° hypothermia Obtain labs: CBC, blood gas, CMP, INR, PTT, fibrinogen Obtain labs: CBC, blood gas, CMP, INR, PTT, fibrinogen Rewarm Rewarm –Passive external, active external, and/or active core rewarming Treat injuries, infections, underlying medical problems Treat injuries, infections, underlying medical problems

13 Passive external rewarming Ideal for mild hypothermia Ideal for mild hypothermia Insulation with blankets, aluminized body covers, etc. Insulation with blankets, aluminized body covers, etc.

14 Active Rewarming For moderate-severe hypothermia (T<32°C), passive warming failure, peripheral vasodilation, secondary hypothermia, endocrine insufficiency For moderate-severe hypothermia (T<32°C), passive warming failure, peripheral vasodilation, secondary hypothermia, endocrine insufficiency External warming External warming –Hot water bottles, forced circulated hot air e.g. Bair Hugger, heating blankets, etc  apply to THORAX, not extremities Core warming Core warming –Heated humidified oxygen, heated IV fluids, gastric/colonic/mediastinal/thoracic/peritoneal lavage with warm saline, extracorporeal blood rewarming

15 Medications in hypothermia Medications are temperature dependent Medications are temperature dependent Often ineffective during hypothermia then become toxic during warming Often ineffective during hypothermia then become toxic during warming Poor GI absorbtion  do not give oral meds Poor GI absorbtion  do not give oral meds Erratic intramuscular absorbtion  avoid IM meds Erratic intramuscular absorbtion  avoid IM meds

16 Hypothermia summary Symptoms often vague, wide variety of presenting symptoms Symptoms often vague, wide variety of presenting symptoms Pre-hospital treatment Pre-hospital treatment –Rescue –Remove wet clothing, stabilize injuries –Limit rewarming –Gentle handling, keep horizontal –Insulate –Transport to hospital Emergency Dept Treatment Emergency Dept Treatment –IV/O2/Monitor –Warmed IV normal saline –CPR/rescue breathing –Passive external, active external, and/or active core rewarming –Treat injuries, infections, underlying medical problems

17 Reference: Reference: Auerbach, P.S. (1995), Wilderness Medicine, 3 rd edition. Mosby. Auerbach, P.S. (1995), Wilderness Medicine, 3 rd edition. Mosby.


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