Hypo/Hyper thermia

Distinguish between primary and secondary hypothermia

What makes heat loss more rapid?

• Primary: From exposure to low temperature

• Secondary: Due to thermoregulatory dysfunction

  • ***Hypoglycemia, Hypothyroid or Sepsis* **

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• Heat loss occurs more rapidly with high wind velocity/windchill factor, water exposure, wet clothing, or direct contact with a cold surface

What are the effects of hypothermia

hypothermia causes:

• generalized slowing of enzymatic activity

• peripheral vasoconstriction

• uncoupling of oxygen-dependent metabolism

1. Differentiate between accidental and environmental hypothermia

2. What increases risk of hypothermia

• Accidental Hypothermia

  • occur iatrogenically in hospital setting due to:

    • rapid infusion of IV fluids

    • prolonged exposure during resuscitation or surgical procedures

    • admin of large amounts of refrigerated stored blood products (without rewarming).

• Environmental Hypothermia

  • Exposure to an environment that brings the core body temperature (CBT) to </= 35C/95F

    • Ambient temp: 40-50; 60 if combined w/ wind, sweat, precipitation, and inadequate shelter

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What increases risk of hypothermia

• Age extremes, underlying medical conditions, and decreased muscle mass

List the Hypothermia Signs and Symptoms:

• 32C/89.6F - 35C/95F:

• 32C/89.6 F - 28C/82.4 F

• < 28C (82.4F) (severe)

Hypothermia Signs and Symptoms:

32C/89.6F - 35C/95F:

• Tachycardia, tachypnea, HTN, shivering

• impaired coordination

• poor judgment

• apathy

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32C/89.6 F - 28C/82.4 F

• General metabolic and physiologic slowing

• Bradycardia, dilated pupils, slowed reflexes, cold diuresis, confusion and lethargy

• Shivering stops

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< 28C (82.4F) (severe)

• Blue or puffy skin

• Coma

• Apnea

• Loss of reflexes

• Asystole or V-Fib

What can prolonged hypothermia lead to?

Prolonged hypothermia may lead to

• Dysrhythmias

• Acidemia

• Hyperkalemia

• Rhabdomyolysis

• Pulmonary edema

• Kidney disease

• Pneumonia

• Pancreatitis

• Hypoglycemia or Hyperglycemia

• Coagulopathy

1. How do we treat hypothermia?

2. What are the rewarming concerns?

Hypothermia Treatment

• ABC's

• REWARMING

• Prevent further heat loss

• Remove cold, wet clothing

• Rectal or bladder probe to monitor temps

• Associated conditions

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Rewarming Concerns

• regularly vs continuously monitor core temperature, vital signs, cardiac rhythm, and glucose

• Complications often occur as colder peripheral blood returns to central circulation

  • core temp afterdrop

  • lactic acidosis

  • V-fib and other arrhythmias

Differentiate between passive and active external rewarming

Passive External Rewarming

• reserved for mild hypothermia

• Methods

  • Remove cold, wet clothing

  • Cover with blankets 

  • Use external radiant heat (if possible)

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Active External Rewarming

• Safe and effective

• Noninvasive

• Methods:

  • Apply external heat to patient's skin

  • Warm bedding (heated blankets)

  • Heat packs

  • Immersion into a 40C bath

NOTE: Patients with mild hypothermia (>33 C) and prior good health usually respond well to passive and active external warming

How would you manage the < 30C victim

initial treatment

• Active rewarming

• CPR

• No more than one shock attempt for dysrhythmia

• Withholding IV cardiac medications

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Once CBT reaches 30C

• Cardiac meds can be given but @ intervals longer than standard

• Defibrillation may be utilized

• Continue resuscitation until CBT at least 35C/95F

Describe Hypothermia Prognosis

• Prognosis is poor with?

• Hypothermia Prognosis

  • If treated early, most otherwise healthy patients survive moderate or severe hypothermia

• Prognosis is poor with 

  • low pH <6.6,

  • elevated potassium >4

  • serious underlying condition

  • Treatment delay

1. List the Heat Related Disorders

2. What are the risk factors

• Heat cramps-mild

• Heat exhaustion-moderate

• Heat syncope-moderate- severe

• Heat stroke-severe

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Risk Factors for Heat disorders

• Exertion in hot climate

• Insufficient acclimatization and/or obesity

• Medical conditions that inhibit sweat production and evaporation

• Dehydration

• Seizures

• Hypotension -> Reduced cardiac output -> Reduced cutaneous blood flow

• Drugs which increase metabolism/muscle activity or impair sweating

Describe Heat Cramps/Exhaustion

• Distinction

• Characterized by

• Clinical Findings

• Treatment

Heat Cramps/Exhaustion

• Distinction:

  • Heat cramps: fluid and electrolyte depletion

  • Heat exhaustion: activity in hot environment w/ inadequate water or salt intake

• Characterized by 

  • dehydration,

  • sodium depletion, 

  • isotonic fluid loss w/ accompanying cardiovascular changes

• Clinical Findings

  • Slow, painful muscle contractions and severe muscle spasms lasting 1-3 minutes

    • usually in muscles that are most heavily used

  • Skin = moist and cool, temperature = normal

  • Muscles = tender, hard and lumpy

  • Muscle twitching may be present

  • History of vigorous activity just preceding onset of symptoms often present

  • Normal labs

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Treatment:

• Move to cool location

• Oral hydration

• Salt replacement

• Rest 1-3 days before returning to activity.

Describe Heat Exhaustion

• Symptoms

• Treatment

Heat Exhaustion: Clinical Findings

• CBT > 37.80 (100.4 F)

• Increased pulse, 

• Orthostatic hypotension

• Moist skin, Sweating

• HA, dizziness, fatigue, anxiety

• Respiratory alkalosis

• Lactic acidosis

• Orthostatic Hypotension

• Variable: 

  • N/V, malaise, 

  • Myalgias,

  • hyperventilation, 

  • thirst, 

  • weakness

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Treatment

• Move to cool environment

• Fluid and electrolyte replacement

  • May need IV fluids

• Active cooling: fans, cool packs

• At least 24 hours of rest and rehydration

Describe Heat Syncope

• What is it

• MOA

• Signs

• Treatment

• What is it?

  • sudden collapse/LOC 

    • after prolonged vigorous activity or prolonged standing in a hot environment

• MOA:

  • volume depletion + cutaneous vasodilation -> systemic/cerebral hypotension

• Signs

  • Cool moist skin

  • Weak pulse

  • Low systolic blood pressure

• Treatment

  • Move to a cool location

  • Lie down

  • Rest

  • Fluid and electrolyte replacement

    • IV fluid if necessary

Describe Heat Stroke

• What is it?

• Groups @ greatest Risk

• Physical Findings

• Lab Abnormalities

• Treatment Goal/Methods

• Complications

Heat Stroke

• What is it?

  • Cerebral dysfunction/altered sensorium

  • Core body temp > 40 C/104 F

• Groups at greatest risk:

  • Extremes of age

  • chronically debilitated

  • Taking meds that interfere with heat-dissipating mechanism:

    • anticholinergics, 

    • antihistamines, 

    • phenothiazines

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Physical Findings

• Hot skin, initially covered with perspiration

  • later dries: Sweating may not be present

• Strong pulse initially

• Widened pulse pressure

• Hypotension develops later in clinical course

• Tachycardia

• Hyperventilation

• Irrational behavior

• Confusion/Altered LOC

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Heat Stroke: Lab Abnormalities

• Hemoconcentration

• Rhabdomyolysis

• Elevated BUN/Creatinine

• Elevated WBC

• Lactic acidosis

• Disseminated Intravascular Coagulation (DIC)

• Anuria

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• Treatments Goal

  • Reducing CBT within 1 hr while supporting circulation to prevent Irreversible tissue damage and death

• Treatments: 

  • IV fluid replacement

  • Rapid cooling

  • Look for possible causes

    • Infection

    • Trauma

    • drug effects

  • Close monitoring

    • vitals,

    • temperature, 

    • cardiac rhythm

  • Shivering must be stopped

    • Benzodiazepines suppresses

  • Skin Massage

  • Cont. tx/rx until cbt -> 39C/102.2; Admit to hospital

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Complications

• Rhabdomyolysis, 

• Renal failure,

• DIC 

• seizures

• Metabolic abnormalities, 

• Cardiac arrhythmias, 

• coagulopathy,

• ARDS, 

• hypoglycemia, 

• Organ dysfunction, 

• Infection

Differentiate between Evaporative and Conductive Cooling

• What is it?

• Method?

Evaporative cooling: 

• What is it?

  • Cools through heat evaporation

• Method

  • Large fans while undressed pt is sprayed with lukewarm water

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Conductive cooling: 

• What is it

  • Cools through skin contact

• Method:

  • cool fluid infusion, 

  • lavage, 

  • ice packs, 

  • immersion into cool water

  • IV cool fluids, 

  • hemodialysis