Hypothermia,&,Frostbite1

Sepi Jooniani, PGY-2 Henry Ford Hospital October 1st, 2015

HYPOTHERMIA1

Definition1Core body temperature <35°C (95°F)

Mild1 35B32,°C,1

Moderate1 32B28,°C,1

Severe1 <28,°C,1

Profound1 <24,°C,1

International,Commission,for,Mountain,Emergency,Medicine1

Mild1 35B32°C,1

Moderate1 32B28°C,1

Severe1 <28,°C,1

Profoud11

<24,°C,11

Measuring,Core,Body,Temperature1

•  Rectal •  Bladder •  Esophageal** •  Tympanic

Epidemiology1•  700 Deaths

•  49%, 65 years or older

•  In-hospital mortality: 40% if moderate/severe

•  Urban settings majority

Classifications1

<1hr

•  Sudden rapid cooling o  Injured alpine climber

ACUTE1 SUBACUTE1 CHRONIC1

Classifications1

1-24 hr o  Unijured climber, stranded

ACUTE1 SUBACUTE1 CHRONIC1

Classifications1

>24hr •  Urban winters o  Psychiatric disorders/

Intoxicated o  Homeless

SUBACUTE1 ACUTE1 CHRONIC1

Etiology1•  Primary •  Secondary

Pathophysiology,of,Thermoregulation1

37°C ± 0.5

Anterior Preoptic Hypothalamus

Temperature,Homeostasis1THERMOLYSIS THERMOGENESIS

•  Conduction •  Convection** •  Radiation •  Evaporation

Nonshivering Thermogenesis

o  Autonomic: peripheral vasoconstriction

o  Endocrine: thyroid, adrenals

o  Adaptive behavioral responses

Shivering Thermogenesis

o  Skeletal muscle activity

o  Heat as byproduct

Increase,in,BMR1

Initial Cooling Phase

Tissue Metabolism Neuronal Activity

Shivering BMR Ventilation Cardiac Output

ADYNAMIC PHASE

Shivering less effective

30°C BMR 50% Dysrythmias

Mild1 35B321

Moderate1 32B281

Respiratory,Changes1•  Initial RR increase, then decrease •  Respiratory arrest at 24 °C •  Increased amount/viscosity of lung secretions •  Decreased elasticity and compliance of chest wall •  Reduced oxygen release to tissues

Cardiac,Changes1•  Initial HR increase, then decrease •  BP falls, Vfib/asystole <28°C

•  Death from primary hypothermia is due to failure of myocardial conduction

CNS,Changes1•  Agitation, shivering

•  AMS, no shivering

•  < 30oC Pupils dilated, hyporeflexic

•  < 28oC Hypertonic coma

o  pseudo rigor mortis

Other,Physiologic,Changes1

•  Kidneys o  Impaired concentrating ability, cold-diuresis, significant volume losses

•  MSK o  Risk of Rhabdomyolysis

•  Heme o  Hemoconcentration, poor circulation o  Risk of thrombosis, DIC

Mild 35-32 °C “Excitation Phase”

Tachypnea, Tachycardia, Hyperventilation, Impaired judgement, Ataxia, Shivering Cold-diuresis

Moderate 32-28 °C “Slowing Phase”

Bradypnea, Bradycardia, Hypoventilation, CNS depression, AMS, Hyporeflexia, Loss of shivering, Paradoxical undressing Reduced RBF, Arrythmia (Afib/junct brady)

Severe <28 °C “Cardiopulm Failure”

Bradycardic, Hypotension Pulm edema, oliguria, Coma, Areflexia, Hypertonic Ventricular arrythmia, Vfib/asystole

Clinical,Presentation1

Lab,Work,Up1

Lab,Work,Up1•  Serum cortisol/thyroid (failure to rewarm)

•  PEARLS *Hct increases 2% for each 1°C drop *Insulin is ineffective <30°C *Hypothermia obstructs hyperK EKG changes

EKG,changes1•  Slowed impulse conduction, prolonged intervals •  J point elevation, Osborne wave (V2-V5)

DDx1BEWARE ! If VS and level of consciousness inconsistent with degree of hypothermia, consider DDx

o  Hypothyroid o  Adrenal insufficiency o  Sepsis o  NMJ disease o  Malnutrition/thiamine def o  Hypoglycemia o  ETOH abuse/drugs

o  CO poisoning

General,Principles,of,Management1

•  ABCs •  Prevention of further heat loss •  Initiate appropriate rapid rewarming if core temp

<35 •  Monitor core temp and pulse •  Careful transport to hospital**

Rewarming,Methods1•  Active Internal

Rewarming (AIR) •  Passive External

Rewarming (PER) •  Active External

Rewarming (AER)

*Based on degree of hypothermia, cardiovascular status * Step-wise approach

Passive,External,Rewarming,(PER)1

•  Supplemental method •  Capable of generating body heat—body self-

corrects •  Mild hypothermia

o  Blankets o  Warm room >28°C

* Recommended rewarming rate : 0.5°C- 2°C/hr

Active,External,Rewarming,(AER)1

•  Moderate (or refractory Mild) Hypothermia

o  Warm water immersion o  Radiant heat (lamp, electric blanket) o  Warm packs o  Forced hot air (bair hugger)

*Rewarming Shock o  Peripheral vasodilation

*Core Temperature Afterdrop in Chronic Hypothermia o  Cold acidemic blood thaws in extremities o  Rewarm trunk BEFORE extremities

Active,Internal,Rewarming,(AIR)1

•  Core Rewarming •  Severe Hypothermia (or refractory Moderate)

o  Warm humidified oxygen 40-42°C o  Warm IVF 40-42°C o  Bladder Irrigation/Gastric Lavage

o  Periotoneal/Pleural irrigation o  Endovascular rewarming via fem cath o  Extracorporeal blood rewarming o  HD o  Cardiopulmonary Bypass

Arrhythmias1•  Bradycadia, physiologic

o  Not responsive to atropine o  no pacing, unless persists beyond warming to >32°C

•  Slow Afib o  usually no RVR, resolved with rewarming

•  Ventricular arrythmia, problematic o  Transcutaneous pacing > transvenous o  Lack of evidence, reasonable to follow ACLS, including defibrillation o  Trial of defib, otherwise CPR/rewarming

Failure,to,Rewarm1•  Reasonable to treat potential adrenal or thyroid

insufficiency

PEARLS1•  Hypotension

o  Moderate/severe hypothermia: disproportionately hypotensive o  Severe dehydration and fluid shifts

•  2 large bore peripheral IVs o  Large volume

•  Warmed isotonic crystalloids 40-42°C •  CVC

o  Femoral to avoid RA irritation

•  Refractory o  Low dose dopamine, 2-5mcg/min

Resuscitation,Efforts1•  Continued Indefintiely

o  Temperature Goal 32-35°C

When to stop: •  K>10-12

o  Severe cell lysis

•  Fibrinogen <50 o  Intravascular thrombosis

•  Ammonia > 420 •  Body is frozen: chest wall incompressible, or nose

and mouth completely blocked by ice

Summary,Rewarming1

Remember!'•  Not Dead, until Warm and Dead

•  Neuroprotection from hypothermia may allow meaningful recovery despite prolonged arrest

DERMAL,COLD,INJURIES,&,FROSTBITE1

Chillblains,(Pernio)1•  Localized inflammatory lesion

o  Repetitive damp/NONfreezing temperatures

•  Hands, ears, feet •  Cutaneous manifestations

o  Within 12 hours

o  Plaques, nodules, ulcerations, vesicles o  Edema, erythema, cyanosis, o  Painful, pruritic

•  Children/women o  Raynauds

Trench,(Immersion),Foot1•  1914, WWI •  Direct injury to sympathetic nerves and vasculature •  Cold, wet, pressure •  Cutaneous manifestations

o  Hours-Days o  Pale, mottled, edematous, painful! numb, pulseless, immobile, ulcers o  Hemorrhagic bullae o  Unchanged after rewarming

•  May progress to gangrene, requiring amputation

Frostnip1•  Localized, cold-induced parasthesias

o  Superficial vasoconstriction o  Tingling, pain, numbness

•  Reversible •  Complete recovery in 1-2 weeks

Frostbite1•  Localized, cold-induced injury •  Freezing of tissues

•  Heat loss > local tissue perfusion o  Freezing point: 4°C

•  Irreversible o  Extent/Duration of freezing o  Duration of exposure, humidity, wind, altitude, clothing, comorbid medical

conditions

Epidemiology1•  Indaquate clothing

o  Most preventable cause o  Head/neck account for 80% heat loss

•  Intoxicated persons majority of frostbites in US o  ETOH o  Other drugs

Predisposing,Factors1•  Hypothermia, Trauma •  Disease states

o  Atherosclerosis, arteritis, hypovolemia, diabetes, vascular injury

•  Nicotine use •  Prior Frostbite •  Intoxication/Psychiatric Disease •  Dark-skinned people •  People from warmer climates

Interestingly1•  Facial, upper airway, esophageal frostbite •  Recreational inhalation of halogenated

hydrocarbons

Pathophysiology1•  Intra/Exracellular ice crystal formation •  Fluid/electrolyte shifts •  Disrupt cell membrane, Lysis

•  Tissue ischemia, necrosis •  Continues with thawing

Thromboxane,A21,PG,F2Bα1

Bradykinins1Histamine1

Clinical,Manifestation1•  Complaints

o  Numbness, pain, clumsiness

•  Cutaneous Manifestations o  Insensate, hard, waxy, o  Clear or hemorrhagic bullae o  If delayed, eschar

•  Ears, nose, chins, cheek, fingers, toes •  Clinical diagnosis

•  XR, Technetium scintigraphy, MRI

•  Delayed Demarcation o  “Frostbite in January, Amputation in July”

Classifications,of,Frostbite1

1st Degree Central pallor, anesthesia, surrounding edema

2nd Degree Large, clear blisters, surrounding edema/erythema, Extend to digit tips, Within 24h, NO tissue loss

3rd Degree Deeper, smaller blisters, Hemorrhagic, more proximal, Eschar

4th Degree Muscle, bones, Tissue necrosis, Mummification in 5-10d

What,degree?1

What,degree?1

What,Degree?1

What,Degree?1

TreatmentB,Prehospital1•  Warm environment •  Pad/splint extremity •  Remove wet clothing •  DO NOT REWARM, avoid refreezing •  Do not rub •  Do not walk on frostbitten feet

TreatmentB,In,Hospital1•  Rewarming *PAINFUL

o  Immersion, 37-39°C o  15-30min , complete when skin is red/purple, soft

•  Thrombolysis o  Decreased rate of amputation (evidence retrospective, small n) o  IN SUMMARY

•  Outcomes often poor •  At high-risk for amputation, within 24h, no C/I: IA tPA+IA heparin

TreatmentB,Wound,Care1•  Aspetic conditions •  Nonadherent gauze, first layer •  Padding- fluff dressing •  Padding between digits •  Avoid occlusive dressing •  Allow to dry after rewarming before dressing

TreatmentB,Blisters1To Debride or Not To Debride?

•  Inflammatory mediators within the blister fluid •  Debride large clear blisters that interfere w

movement •  Large hemorraghic bullae aspirated, not debrided

Treatment,continued1•  Prophylactic Antibiotics?

NO

•  Tetanus? YES

•  NSAIDS? YES

•  Surgical consult? YES •  Complications: long-term wound care, debridement, amputation,

fasciotomy

Other,Complications1•  Early

o  Infection o  Gangrene o  Autoamputation

•  Late

o  Persistent pain/parasthesias o  Hypersensitivity to cold exposure o  Re-exposure vasospasm

•  Other o  Scarring, tissue atrophy, arthritis, bony abnormalities

References1•  Zafren, K. Accidental Hypothermia in Adults. In: UpToDate. Post

DD (Ed) UpToDate •  Zafren, K. Frostbite. In: UpToDate Post DD (Ed). UpToDate •  Headdon W. The management of accidental hypothermia. BMJ

2009; 338: b2085 •  2005: American Heart Association Guidelines for

Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Part 10.2: Hypothermia. Circulation 2005; 112:IV

•  Nolan J. Images in Resuscitation: the ECG in hypothermia. Resuscitation 2005; 64:133

•  Muprhy. Frostbite: pathogenesis and treatment. J Trauma 2000; 48:171

•  Atenstaedt R. Trench foot: the medical response in first World War 1914-1918. Wilderness Environ Med 2006; 17:282

•  Bhatnagar, A. Diagnosis, characterization, and evaluation of treatment response of frostbite using pertechnetate scintihraphy: a prospetice study. Eur J Nucl Med Mol Imaging. 2002; 29:170