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Temperature-Related Illnesses
Dorothy W. Bird, MD
Suresh Agarwal, MD
Department of Surgery
Boston University Medical Center
Temperature-Related Illness
• Hypothermia
– Systemic Hypothermia
– Non-freezing Injuries
– Freezing Injuries
• Hyperthermia
– Heat Exhaustion
– Heat Stroke
– Drug-Induced Hyperthermia
Slide 3
Heat Exchange Mechanisms
Radiation: loss of heat by infrared rays
Conduction: transfer of heat from object to object
Convection: current of air carrying heat away from skin
Evaporation: warming of water to transform it from liquid to
Slide 4
Normal Temperature Regulation
• Human body generates 1oC/hour
• Transfers heat to the environment to maintain body
temperature +/- 0.6oC
• Normal body temperatures:
– 32oC skin
– 37oC sublingual
– 38oC rectum
– 38.5oC deep liver
Slide 5
• <35oC (95oF)
• Primary (accidental): decrease in core body temperature
from environmental cold stress
• Secondary: due to metabolic disorder resulting in
abnormal heat production or heat-conserving
Slide 6
Hypothermia - Systemic Effects
• A. Cardiovascular
– Delayed bradycardia (32oC)
– ↓MAP, ↓contractility, ↓CO
– EKG: J-wave, PR, QRS, QT prolongation
– 30oC atrial or ventricular fibrillation
– 25oC asystole
• B. Respiratory
– ↓RR, hypoxia, respiratory acidosis
– ↑mucus (cold bronchorrhea)
– ↓ciliary action, ↓cough reflex; pneumonia
Slide 7
Slide 8
Hypothermia – Systemic Effects
• C. CNS
– Abnormal EEG <34oC; Flat EEG 19-29oC
– Hyper-reflexia >32oC; Hypo-reflexia <32oC
– ↓Mentation, ↓Motor function
• D. Coagulation
– Platelet sequestration (portal), thrombocytopenia
– Impaired platelet function
– Coagulation factors: ↓40% activity, ↑PT, PTT
– DIC-like syndrome, risk of thromboembolic event
Slide 9
Hypothermia – Systemic Effects
• E. Renal
– ↓Na+ reabsorption
• F. GI
– Ileus, bowel wall edema, impaired hepatic drug
detoxification, pancreatitis, hyperamylasemia,
gastric erosions
Slide 10
Hypothermia – Systemic Effects
• G. Endocrine
– Hyperglycemia
• H. Immune
– ↓endothelial cell adhesion results in ↑infection
Slide 11
Hypothermia - Management
• ABCs first!
• May be hard to palpate pulse/BP in cold, stiff victim
• EKG: look for any organized rhythm as evidence of life
• CPR ONLY in absence of cardiac rhythm
• NO cardiac drugs or defibrillation <28oC
Slide 12
Hypothermia - Rewarming
• Mild Hypothermia (32-35oC)
– Warm environment – blanket, head cover
• Moderate Hypothermia (30-32oC)
– Heating pad, warm water immersion
• Severe Hypothermia (<30oC)
– Warm IV fluids (65oC) / blood products (49oC)
– Cardiopulmonary bypass
– Lavage
Slide 13
Re-warming Rates
• Spontaneous: 1.2oC/h
• Spontaneous + Shivering: 3.6oC/h
• Passive External Rewarming: 0.5-2.0oC/h
• Active External Rewarming: 1.0-2.5oC/h
• Body Cavity Lavage: 1.0-3.0oC/hour
• Cardiopulmnary Bypass: 1.0-2.0oC/3-5min
• CAVR: 1oC/15.4 min
Slide 14
• Continuous arteriovenous re-warming
• Level I warming system
• Percutaneous femoral arterial and venous lines
• Creates AV fistula where blood is pumped via patient’s
own BP through external warming system
• More rapid re-warming than other methods
• Less invasive, no heparinization needed
• Improved survival, multisystem organ failure, SICU stay
vs other methods
Slide 15
Hypothermia in Trauma
• Very common after injury
• A form of secondary, unintentional hypothemia
• Ominous sign!!
– Worsened outcome / mortality if due to trauma
– ↑ mortality if patient controlled for ISS, shock,
resuscitation volume
Slide 16
Hypothermia in Trauma
• Stricter Severity Classification:
– Mild: 36-34oC
– Moderate: 34-32oC
– Severe: <32oC
• Rapid re-warming with CAVR proven more effective
• Failure to re-warm is detrimental to survival!
Slide 17
Non-freezing Injury
• Chilblain (Pernio)
– Cause: Repeated exposure to cold above freezing
– Pathophysiology: chronic dermal vasculitis
– Appearance: pruritic, red-purple papules, maculares,
plaques, nodules, edema, blisters
– Treatment: shelter, elevation on sheepskin, gradual
rewarming at room temperature
– Sequelae: dermopathy; treat with antiadrenergic
(prazosin) or calcium-channel blocker (nifedipine)
Slide 18
Slide 19
Non-freezing Injury
• Trench foot (hand)
– Cause: chronic exposure to wet conditions just above freezing
– Pathophysiology: alternating arterial vasospasm and vasodilation
– Appearance: edema, blisters, redness, ecchymosis, ulceration
– Treatment: removal from cold, wet environment; gentle warm,
dry air; elevation; wound care
– Sequelae: cellulitis, lymphangitis, gangrene, demyelation,
atrophy, osteoporosis, fallen arches
Slide 20
Trench Foot
Slide 21
• Freezing injury: Ice crystal formation, cellular
dehydration, microvascular occlusion
• Pathophysiology:
– 1. cellular death from freezing cold
– 2. alternating vasoconstriction/vasodilation (Hunting
reaction)→ repeat freeze/thaw cycle→ ↑blood
viscocity→ progressive thrombosis→
– 3. re-warming→ secondary ischemia/reperfusion
Slide 22
• Classification:
– 1st Degree: tissue freezing, central white anesthetic
patch, surrounding erythema
– 2nd Degree: tissue freezing, blisters of clear or milky
fluid, surrounding edema/erythema
– 3rd Degree: tissue freezing and subcutaneous/skin
death, hemorrhagic blisters, black eschar (2 weeks)
– 4th Degree: tissue necrosis, gangrene, full-thickness
tissue loss; hard, cold white, anesthetic
Slide 23
Slide 24
1. Pre-thaw/Pre-hospital Phase
– Protect injured limb from trauma
– No thawing until definitive re-warming is ensured
– NO rubbing!
Slide 25
2. Re-warming/Hospital Phase
– Rapid re-warming: immersion in large water bath (4042oC) x30-45 minutes
– Narcotic pain relief as needed
3. Post-thaw Phase
– Wound care: clean and dry skin, elevate, sterile
cotton applied between affected toes/fingers, protect
from unintentional trauma with tent/cradle
Slide 26
• Wound Care
• Uninfected blebs: keep intact (self-dressing)
• Daily or BID dressing change/cleansing in warm
whirlpool bath
• Aloe vera cream (thromboxane inhibitor)
• Physical therapy with edema resolves
• No tobacco, nicotine, vasoconstrictors
Slide 27
• Sequelae
• Cold insensitivity
• Hyperhidrosis
• Neuropathy
• ↓ nail/hair growth
• Persistent Raynaud’s phenomenon
• ↑ risk for re-injury
Slide 28
• Hyperthemia vs. Fever:
– elevated body temperature
– Hyperthermia: abnormal temperature regulation
– Fever: normal temperature regulation with elevated
• Hyperpyrexia: extreme temperature elevation (>40oC)
Slide 29
Heat Exhaustion
• Heat exposure resulting in volume depletion
• Flu-like symptoms:
– Hyperthermia(>36oC), muscle cramps, nausea,
malaise, tachycardia
– Hypernatremia (sweating)/Hyponatremia ( excessive
water consumption)
• No neurologic impairment
• Treatment: volume/electrolyte repletion
Slide 30
Heat Stroke
• Extremely elevated body temp (>41oC)
• Neurologic dysfunction Severe volume depletion,
hypotensive, multiorgan failure, rhabodmyolysis, acute
renal failure, DIC, transaminitits
• Anhidrosis
• Classic Type
• Exertional Type
Slide 31
Heat Stroke Treatment
• Volume and electrolyte repletion
• Immediate cooling
– External cooling: ice pack to groin, axilla, ice to neck,
chest; cooling blankets
– Evaporative cooling: spray skin with cool water and
fan; will decrease temp by 0.3oC/min
– Internal cooling: cold water lavage to stomach,
bladder, rectum
Slide 32
Drug-Induced Hyperthermia
• Malignant Hyperthermia (MH)
• Excessive calcium efflux from sarcoplasmic reticulum in
response to halogenated inhalational agents
• Results in uncoupling of oxidative phosphorylation with
dramatically increased metabolic rate
• Incidence: 1:15,000 episodes of general anesthesia
• Affects 1:50,000 people
• Autosomal dominant inheritence
Slide 33
Malignant Hyperthermia
• Signs
• FIRST: sudden rise in end-tidal CO2
• Muscle rigidity
• Hyperthermia
• Depressed consciousness
• Autonomic instability
• Leads to: myonecrosis, rhabdomyolysis, acute renal
Slide 34
Malignant Hyperthermia
• Management
– Discontinue anesthetic agent
– DANTROLENE- blocks Ca++ efflux from S.R.
• First: 1-2mg/kg IV bolus q15 min to max total 10mg/kg
• Then: 1mg/kg IV (or 2mg/kg PO) QID x 3 days
• Reduces mortality from 70% to 10%
• Victims should wear ID band and family should be tested
Slide 35
Neuroleptic Malignant Syndrome
• Idiosyncratic drug reaction to usage or discontinuation of
neuroleptic drugs that alter dopamine axis
• Symptoms: hyperthermia, lead-pipe rigidity, altered
mental status, autonomic instability
• 20% mortality
• 0.2%-1.9% incidence (of those on neuroleptics)
• Most common: Haloperidol, Fluphenazine
• No relationship to duration or dosage
– Usually seen 24-72 hours after starting/ending drug
Slide 36
• Treatment
• Discontinue offending new medication or resume
dopaninergic therapy if recently stopped
• Volume resuscitation
• DANTROLENE: 2-3mg/kg/ IV q few hours to max total
– Give with heparinization due to increased
thromboembolism risk
Slide 37
Serotonin Syndrome (SS)
• Caused by overstimulation of serotonin receptors in CNS
– Associated with SSRI, NMDA, amphetamine use
• Exam: abrupt onset of altered mental status
– Autonomic hyperactivity
– Mydriasis, diaphoresis
– Tachycardia, hypertension
– Hyperthermia
– Hyperkinesia, ↑DTR, rigidity, clonus (deep patellar,
horizontal occular clonus)
Slide 38
Serotonin Syndrome
• Treatment
• Discontinue medication
• Benzodiazepine (control agitation, hyperkinesia)
• Cyproheptadine (serotonin agonist)
– Only for severe SS
– Give 12mg PO/NG then 2mg PO q2h PRN symptoms
• Neuromuscular paralysis (Vecuronium)
Slide 39
• Jurkovich GJ. Environmental Cold-Induced Injury. Surg
Clin N Am 2007;87(4):247-267.
• Petrone P, Kuncir EJ, Asensio JA. Surgical
management and stratagies in the treatment of
hypothermia and cold injury. Emerg Med Clin N Am
• Hall JB, Schmidt GA, Wood LDH. Principles of Critical
Care 3rd Ed. The McGraw-Hill Companies, 2005.
• Marino PL. The ICU Book, 3rd ed. New York:
Lippincott Williams & Wilkins, 2007:697-712.
Slide 40