Hypothermia,&, Frostbite1. Sepi Jooniani, PGY-2 Henry Ford Hospital October 1 st, 2015

Transcription

1 Hypothermia,&, Frostbite1 Sepi Jooniani, PGY-2 Henry Ford Hospital October 1 st, 2015

2 HYPOTHERMIA1

3 Definition1 Core body temperature <35 C (95 F) Mild1 35B32, C,1 Moderate1 32B28, C,1 Severe1 <28, C,1 Profound1 <24, C,1

4 International,Commission,for, Mountain,Emergency,Medicine1 Mild1 Moderate1 Severe1 Profoud1 1 35B32 C,1 32B28 C,1 <28, C,1 <24, C,1 1

5 Measuring,Core,Body, Temperature1 Rectal Bladder Esophageal** Tympanic

6 700 Deaths Epidemiology1 49%, 65 years or older In-hospital mortality: 40% if moderate/severe Urban settings majority

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8 Classifications1 ACUTE1 SUBACUTE1 CHRONIC1 <1hr Sudden rapid cooling o Injured alpine climber

9 Classifications1 ACUTE1 SUBACUTE1 CHRONIC hr o Unijured climber, stranded

10 Classifications1 SUBACUTE1 ACUTE1 CHRONIC1 >24hr Urban winters o Psychiatric disorders/ Intoxicated o Homeless

11 Primary Secondary Etiology1

12 Pathophysiology,of, Thermoregulation1 Anterior Preoptic Hypothalamus 37 C ± 0.5

13 Temperature,Homeostasis1 THERMOLYSIS THERMOGENESIS Conduction Convection** Radiation Evaporation Shivering Thermogenesis o Skeletal muscle activity o Heat as byproduct Nonshivering Thermogenesis o Autonomic: peripheral vasoconstriction o Endocrine: thyroid, adrenals o Adaptive behavioral responses Increase,in,BMR1

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15 Initial Cooling Phase ADYNAMIC PHASE Mild1 35B321 Tissue Metabolism Neuronal Activity Shivering BMR Ventilation Cardiac Output Moderate1 32B281 Shivering less effective 30 C BMR 50% Dysrythmias

16 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

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18 Cardiac,Changes1 Initial HR increase, then decrease BP falls, Vfib/asystole <28 C Death from primary hypothermia is due to failure of myocardial conduction

19 Agitation, shivering CNS,Changes1 AMS, no shivering < 30 o C Pupils dilated, hyporeflexic < 28 o C Hypertonic coma o pseudo rigor mortis

20 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

21 Clinical,Presentation1 Mild C Excitation Phase Moderate C Slowing Phase Tachypnea, Tachycardia, Hyperventilation, Impaired judgement, Ataxia, Shivering Cold-diuresis 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

22 Lab,Work,Up1

23 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

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

25 DDx1 BEWARE! 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

26 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**

27 Rewarming,Methods1 Passive External Rewarming (PER) Active External Rewarming (AER) Active Internal Rewarming (AIR) *Based on degree of hypothermia, cardiovascular status * Step-wise approach

28 Passive,External, Rewarming,(PER)1 Supplemental method Capable of generating body heat body selfcorrects Mild hypothermia o Blankets o Warm room >28 C * Recommended rewarming rate : 0.5 C- 2 C/hr

29 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

30 Active,Internal, Rewarming,(AIR)1 Core Rewarming Severe Hypothermia (or refractory Moderate) o Warm humidified oxygen C o Warm IVF 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

31 Bradycadia, physiologic o Not responsive to atropine Arrhythmias1 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

32 Failure,to,Rewarm1 Reasonable to treat potential adrenal or thyroid insufficiency

33 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 C CVC o Femoral to avoid RA irritation Refractory o Low dose dopamine, 2-5mcg/min

34 Resuscitation,Efforts1 Continued Indefintiely o Temperature Goal 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

35 Summary,Rewarming1

36 Remember!' Not Dead, until Warm and Dead Neuroprotection from hypothermia may allow meaningful recovery despite prolonged arrest

37 DERMAL,COLD,INJURIES, &,FROSTBITE1

38 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

39 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

40 Frostnip1 Localized, cold-induced parasthesias o Superficial vasoconstriction o Tingling, pain, numbness Reversible Complete recovery in 1-2 weeks

41 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

42 Indaquate clothing o Most preventable cause Epidemiology1 o Head/neck account for 80% heat loss Intoxicated persons majority of frostbites in US o ETOH o Other drugs

43 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

44 Interestingly1 Facial, upper airway, esophageal frostbite Recreational inhalation of halogenated hydrocarbons

45 Pathophysiology1 Intra/Exracellular ice crystal formation Fluid/electrolyte shifts Disrupt cell membrane, Lysis Thromboxane,A21,PG,F2Bα1 Bradykinins1 Histamine1 Tissue ischemia, necrosis Continues with thawing

46 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

47 Classifications,of,Frostbite1 1 st Degree Central pallor, anesthesia, surrounding edema 2 nd Degree Large, clear blisters, surrounding edema/ erythema, Extend to digit tips, Within 24h, NO tissue loss 3 rd Degree Deeper, smaller blisters, Hemorrhagic, more proximal, Eschar 4 th Degree Muscle, bones, Tissue necrosis, Mummification in 5-10d

48 What,degree?1

49 What,degree?1

50 What,Degree?1

51 What,Degree?1

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

53 TreatmentB,In,Hospital1 Rewarming *PAINFUL o Immersion, 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

54 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

55 TreatmentB,Blisters1 To 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

56 Treatment,continued1 Prophylactic Antibiotics? NO Tetanus? YES NSAIDS? YES Surgical consult? YES Complications: long-term wound care, debridement, amputation, fasciotomy

57 Early o Infection Other,Complications1 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

58 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: b : 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 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