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Critical Temperature-Related Illnesses

Dorothy W. Bird, MD

Suresh Agarwal, MD

Department of Surgery

Boston University Medical Center

Slide 3

Temperature-Related Illness

• Hypothermia

– Systemic Hypothermia

– Non-freezing Injuries

– Freezing Injuries

• Hyperthermia

– Heat Exhaustion

– Heat Stroke

– Drug-Induced Hyperthermia

Slide 4

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 gas

Slide 5

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 6

Hypothermia

• <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 mechanism

Slide 7

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 8

J-Wave

• http://www.rcsed.ac.uk/fellows/bcpaterson/new_page_3.htm

Slide 9

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 10

Hypothermia – Systemic Effects

• E. Renal

– ↓Na+ reabsorption

• F. GI

– Ileus, bowel wall edema, impaired hepatic drug detoxification, pancreatitis, hyperamylasemia, gastric erosions

Slide 11

Hypothermia – Systemic Effects

• G. Endocrine

– Hyperglycemia

• H. Immune

– ↓endothelial cell adhesion results in ↑infection

Slide 12

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 13

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 14

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 15

CAVR

• 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 16

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 17

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 18

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 19

Chilblain

• www.answers.com/topic/chilblain

• www.ohiohealth.com/bodymayo.cfm?xyzpdqabc=0...

Slide 20

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 21

Trench Foot

• www.visualstatistics.net

• www.pbase.com

Slide 22

Frostbite

• 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→ ischemia/necrosis

– 3. re-warming→ secondary ischemia/reperfusion

Slide 23

Frostbite

• 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 24

Frostbite

• www.geradts.com

• www.alpineinstitute.blogspot.com

Slide 25

Frostbite

Treatment

1. Pre-thaw/Pre-hospital Phase

– Protect injured limb from trauma

– No thawing until definitive re-warming is ensured

– NO rubbing!

Slide 26

Frostbite

2. Re-warming/Hospital Phase

– Rapid re-warming: immersion in large water bath (40-42oC) 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 27

Frostbite

• 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 28

Frostbite

• Sequelae

• Cold insensitivity

• Hyperhidrosis

• Neuropathy

• ↓ nail/hair growth

• Persistent Raynaud’s phenomenon

• ↑ risk for re-injury

Slide 29

Hyperthemia

• Hyperthemia vs. Fever:

– elevated body temperature

– Hyperthermia: abnormal temperature regulation

– Fever: normal temperature regulation with elevated set-point

• Hyperpyrexia: extreme temperature elevation (>40oC)

Slide 30

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 31

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 32

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 33

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 34

Malignant Hyperthermia

• Signs

• FIRST: sudden rise in end-tidal CO2

• Muscle rigidity

• Hyperthermia

• Depressed consciousness

• Autonomic instability

• Leads to: myonecrosis, rhabdomyolysis, acute renal failure

Slide 35

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 36

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 37

NMS

• 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 10mg/kg/day

• BROMOCRIPTINE: 2.5-10mg PO TID

– Give with heparinization due to increased thromboembolism risk

Slide 38

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 39

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)

• NO RESTRAINTS

Slide 40

References

• 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 2003;21:1165-1178.

• 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.