11/8/2017

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Spokane County EMS

Road Map

• Thermoregulation

• Cold Related Injuries

• Heat Related Injuries

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Spokane County EMS

Thermoregulation

Pathophysiology of Thermoregulation

• Thermoregulatory center located in the posterior hypothalmus regulates body temperature

• This center receives input from central thermoreceptors in or near the anterior hypothalmus and from peripheral thermoreceptors located in the skin and some mucus membranes.

• Information from these receptors is transmitted via nerves and ascending pathways to the posterior hypothalmus.

• The hypothalmus responds with appropriate output to decrease heat loss- by increasing heat production or increasing heat loss by decreasing heat production

Pathophysiology of Thermoregulation

• Thermoregulatory center has a inherent set point of 37 degrees C (98.6 F)

• Homeostasis – body’s processes of maintaining supply and demand of the body’s needs.

• As it relates to thermoregulation it does this in two ways:– Thermogenesis (heat production)

– Thermolysis (Release of stored heat and energy)

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Thermoregulatory Mechanisms

• Thermogenesis– Main method of dealing with cold stressors

– Skin is the body’s thermostat.

– Increases muscle tone and initiates shivering in the short term

– Increases thyroid levels in the long term

– Hypothalamus shunts blood to the core.

– Sweating decreases.

– Persons physiological & biochemical factors which affect these compensatory mechanism include age, health factors, nutritional status.

Thermolysis can occur in five different ways

+

Thermoregulatory body glands = skin blood flow (vasocontriction or vasodilatation), sweating and shivering

Spokane County EMS

Cold Injuries

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Hypothermia is defined as:

A drop in body temperature below that required for normal metabolism and bodily functions where the amount of heat lost exceeds that which is able to be produced; characterized by a temperature below 95*F (35*C); usually caused by prolonged exposure to cold and/or damp conditions.

Hypothermia

• Body factors– Increased thermolysis

• Out in the environment for an extended period

– Decreased thermogenesis• Shock state

• Anemia

– Impaired thermoregulation• Head injury

• Alcohol on board

• Certain prescription medications

Hypothermia

• Further broken down to primary and secondary hypothermia:– Primary – results from failure of heat generation in the face of a

cold environment …i.e. adaptive processes not working well (muscle activity & shivering) …physical conditioning, dehydration and lack of caloric intake makes the problem worse

– Secondary – results when a disease state interferes with thermoregulation processes and the bodies ability to maintain its own body temperature…primary and secondary can exist concurrently …injury to the hypothalamus (thermoregulatory center)… underlying illness/disease process that compromises regulatory mechanisms…prescription medications that affect a patient’s ability to compensate …bottom line need to have a high degree of suspicion

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Risk Factors for Hypothermia

• Issues leading to the development– Cold temperatures

• Length of exposure

• Intensity of weather conditions

• Improper gear for adverse conditions

– Wetness – of clothes or incontinence

– Dehydration

– Malnutrition

Risk Factors for Hypothermia

• Alcohol / Drug Intoxication– Most common cause of heat loss in urban settings

– Impairs shivering thermogenesis

– Promotes cutaneous vasodilation

– Liver disease creates inadequate glycogen stores and subnormal nutritional status.

– Impairs judgment

Risk Factors for Hypothermia

• Age Extremes – Often cannot generate heat effectively

– Reduced muscle mass and a diminished shivering response

– Certain medications may interfere with vasoconstriction.

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Other Risk Factors

• Diabetic• Fall• Stroke• Cardiac Arrest• Unconscious• Difficulty

Breathing• Toxin exposure

• Immune suppressed• Infection/Sepsis• Pediatric• Allergic Reaction• Altered LOC

AND ALSO…

Risk Factors for Hypothermia

Trauma• Hypothermic temperatures are increased for

trauma patients due to deadly complications such as:– cardiac rhythm changes– hypoglycemia – coagulopathies (blood clotting problems)– hypotension – Hypovolemia

• Trauma patients become hypothermic at a higher temperature than non-trauma patients

Degrees of Hypothermia

Hypothermia is categorized and further defined by “degree”:

(no pun intended )

MILD; MODERATE; SEVERE

.

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PATHOPHYSIOLOGY vs. S/S:

MILD Hypothermia (32-35° 89.6-95°)Hypothalamus initiates sympathetic nervous system response causing an increase in BP, pulse and cardiac output. Vasoconstriction-Blood is redirected to muscles where it can be warmed by the initiation of the shivering response. Increase in metabolism.

Signs and Symptoms in the field:• shivering • hyperreflexia • tachycardia, hypertension, (increased cardiac output) • altered mental status, confusion some may try to be

removing their clothes • tachypnea

PATHOPHYS vs. S/S (Cont):

MODERATE- (28-32° - 82.4-89.6°F)Body unable to reach/maintain functional temperature, shivering stops; metabolism slows down; decreased O2 demand and CO2 production; cold diuresis; dilated pupils.

Signs and Symptoms in the field:• sympathetic nerve impairment hypotension, bradycardia• atrial fibrillation/flutter & ectopy• bradypnea, decreased lung compliance • Altered mental status; loss of consciousness • Coagulopathy • Gag reflex may not be present at <89.9*F.

PATHOPHYSIOLOGY vs. S/S (CONT.):

SEVERE- (<28°- 82.4° F)Systems are hypoxic and exhausted; Metabolic & Respiratory acidosis; unresponsive; pulmonary edema; loss of reflexes.

Signs and Symptoms in the field:• Ventricular fibrillation & asystole increased myocardial

contractility • severe hypotension • decreased/absent respirations • unconscious

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ECG CHANGES IN HYPOTHERMIC PATIENTS (CONT.)

As the core temperature falls, the cardiac rhythm progresses from: Tachycardia Bradycardia Atrial fib (with a slow ventricular rate)

↓

V-fib Asystole

V-fib is usually refractory to defibrillation & Medications until a body temperature of 86*F (30*C) or greater is obtained.

Easy Identification of the Hypothermic Patient:

Look for the “umbles”:

• Stumbles

• Fumbles

• Mumbles

• Grumbles

Questions to ask yourself on scene:

• What are they laying/sitting on?(Tile floor/living room carpet/pavement/car)

• How long have they been there?• What type of environment are they in?

(Temperature/wind)• Are they properly dressed? (For age group/season?)• Are they breathing rapidly?• Are they wet: DIAPHORETIC? incontinence?• Do they have a chronic illness? (COPD, CHF,

Diabetes, neuropathy, cancer)• Are they on multiple medications?• Is there a possibility of head injury?• Are they intoxicated (ETOH/illicit drugs)?

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How do we treat it?

Treatment

• Passive Rewarming – Getting victim out of cold environment

– Blankets

– Removing wet clothes

– Moisture barriers

• Active rewarming: all the above plus– Heat packs

– Warmed IVs

General Treatment:

• Prevent further heat loss (blankets)• Remove wet/restrictive clothing • Remove from environment• Convective (forced air) warming is effective in

restoring heat to the core although radiant heat (hot packs) may be easier to apply.

• Good assessment that includes HPI, any pt. meds• Warmed O2 (if possible)• Glucose check• Cardiac monitoring• VS take longer to check HR & RR• Gentle handling of patient

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Treatment of Hypothermia

• Breathing patients with a pulse– Mild hypothermia cases: 93.2°F

• Passive rewarming • Promote heat generation

– Moderate hypothermia cases: 86°F to 93.2°F• Passive and active external rewarming of the truncal areas

cautiously Afterdrop phenomena

– Severe hypothermia cases: less than 86°F• Passive rewarming only

Role of IV Fluids in the Hypothermic Patient:

• Fluid resuscitation can result in substantial core temperature decreases, mandating the use of efficient fluid-warming devices.

• Fluids are generally infused into the body at or near room temperature

• Consequentially the patient must give up his/her own heat to warm the infused fluids, thus exacerbating the problem of hypothermia.

• Crystalloids should be warmed to at least 104*F(40*C) prior to administration.

ACLS Hypothermia AlgorithmPulse or breathing absent

↓Start CPR

Defibrillate max three timesAttempt, confirm, secure airway

Ventilate with warmed O2IV access - Infuse warm saline

↓Core Temperature

_______________________________________________________________________<30° (86°) >30°

-Continue CPR -Continue CPR-Withhold IV meds -Active rewarming (if within 15 min)-Limit shocks to max of three -Repeat defib as core temp rises -Transport -Give IV Meds – space out longer in time

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Spokane County EMS

Other Cold Related Injuries

Local Cold Injury

• Most injuries are localized to the extremities or exposed parts. – Tips of the ears, nose, upper cheek, and tips

of the fingers or toes

Local Cold Injury

• Frostbite – effects the epidermis & dermis– Environmentally induced freezing of body tissues

– Ice crystals form within and water is drawn out of the cells into extracellular space. As the ice crystals expand they cause destruction of the cellsintracellular electrolyte concentration increases causing further destruction to the cells

– Sludging of cold, viscous blood further contributes to tissue hypoxia…also after thawing cellular level may further compound extent of damage

– Frostbite is classified according to depth of injury

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Local Cold Injury

• Superficial frostbite – epidermis affected– Most common symptoms

• Altered sensation

• Skin typically appears white and waxy.

• Skin is firm to palpation, but the underlying tissues remain soft.

• Capillary leakage produces edema in the frostbitten area.

Local Cold Injury

• Superficial frostbite (cont.)– Most common symptoms (cont.)

• Severe tingling, throbbing pain during rewarming

• Edema accumulation within hours

• Clear fluid filled vesicles within 3-24 hours

• Hard, black eschar within a week

Local Cold Injury

– Prehospital treatment• Differs significantly from that of deep frostbite

• If the tissues beneath the skin are soft when you press down on the skin surface, the frostbite is probably superficial.

• Combination of dressing, rest, food, and limiting exposure

• Get the patient out of the cold.

• Rewarm the injured part with body heat.

• Do not rub or massage the frostbitten area.

• Cover blisters with a dry, sterile dressing.

• Transport the patient to the hospital.

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Local Cold Injury

• Deep Frostbite:– Disrupted nutritional capillary flow never restored to

damaged tissue– Affected area remains cold, mottled and blue or gray

after rewarming.– During first 9-15 days skin forms a black eschar– Edema is slow to form– Deep blisters with purple blood containing fluid

appears within 1-3 weeks– Within 22-45 days a line of demarcation between the

eschar and viable skin developsgangrene

Local Cold Injury

• Prehospital treatment:– Don’t rewarm if chance that extremity could refreeze

– Rewarm if possible and practical in hot water (104°)

– Don’t allow patient to walk on extremity

– No alcohol or tobacco products

– May need pain control

Spokane County EMS

Heat Related Injuries

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Heat Illness

• Increase in core body temperature– Due to inadequate thermolysis– Inability to get rid of the heat buildup in the body

• Body adaptation to Heat:– Body has the ability to acclimatize to hot environments by

decreasing heat production and increasing heat loss efficiency takes 10-60 days

– glycogen stores increase allowing for less heat production– Volume of sweat that is produced is increased – The temperature at which sweating starts is lowered

Risk Factors for Heat Illness

Risk Factors for Heat Illness

• Older people are at a particular risk.– Do not adjust as well to the heat

– Perspire less

– Acclimatize more slowly

– Feel thirst less readily

– Decreased mobility

– More likely to have chronic conditions

– More apt to be taking medications that disrupt the body’s mechanisms for dissipating heat

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Risk Factors for Heat Illness

• Infants and young children exposed to a hot environment– Proportionately higher metabolic heat production

– Body Temperature that rises faster during dehydration

– Do not dissipate heat as well

Heat Cramps

• Acute involuntary muscle pains– Usually in the lower

extremities, the abdomen, or both

– Occur because of profuse sweating and subsequent sodium losses…water follows NaCl(hyponatremia)

© Svetlana Larina/ShutterStock, Inc.

Heat Cramps

• Treatment– Move the patient to a cool environment.

– If the patient is not nauseated, give one or two glasses of a salt-containing solution or sports drink.

– If the patient is too nauseated to take liquids by mouth, insert an IV catheter and infuse normal saline rapidly.

– Do not massage the cramping muscles.

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Heat Exhaustion (Prostration)

• Clinical syndrome– Milder form of heat

illnesses

– Volume depletion and heat stress

Heat Exhaustion

• Symptoms– Headache, fatigue, dizziness, nausea, vomiting, and,

sometimes, abdominal cramping

– Skin is pale and clammy.

– Core temperature mildly elevated (<104°)

– Tachycardia

– Tachypnea

– + Orthostatic VS

– ↓Urine Output

– Sometimes misdiagnosed

– If untreated may progress to heat stroke

Heat Exhaustion

• Treatment– Aimed at removing the patient from exposure to heat

and repairing the derangement in fluid and electrolyte balance

– Move the patient to a cool environment, remove excess clothing.

– If the patient’s temperature is elevated, sponge, spray, or drip the patient with tepid water and fan gently.

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Heat Exhaustion

• Treatment (continued)– Oral hydration with sports drinks– If nausea and vomiting are present, start a normal

saline IV and draw blood for electrolyte determinations.

– Cautiously give fluids by mouth.– Monitor cardiac rhythm, vital signs, temperature– If you cannot determine whether the patient has heat

exhaustion or heat stroke, treat for heat stroke.

Heat Stroke

• Least common but most deadly– Caused by a severe disturbance in the body’s

thermoregulation

– Body’s compensating mechanisms fail

– Two findings• Core temperature more than 104°F (40°C)

• Neurologic dysfunction

• Other systems are affected…organ and tissue damage seems to be more related to duration of elevated temperature (versus the magnitude of the elevation)

Heat Stroke

• Two syndromes– Classic

• Passive heat stroke…80% with sudden onset

• Usually occurs during heat waves

• Often the elderly or debilitated or the young

• Often suffer from chronic illnesses or alcoholism

• May be taking meds that impair adaptation to heat stress

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Heat Stroke

– Exertional• Typically an illness of young and fit people exercising in hot

and humid conditions• Generate heat without any means of excreting that heat• May be very diaphoretic• May be hypoglycemic

Heat Stroke

• The clinical picture of heat stroke– Patients will not be able to give a coherent history. – Earliest signs are changes in behavior.

• Irritability, combativeness, and signs the patient is hallucinating

– Older patients may present with signs resembling those of a suspected stroke.

– Tremors, seizures, constricted pupils, and decerebrate or decorticate posturing

– If CNS intact: • ↑ Cardiac Output Tachycardia progresses bradycardia• Tachypnea Apnea• Sweating

Heat Stroke

• Fever and conditions that mimic heat stroke– History may suggest infectious causes.

– Fever signals that the body is fighting an infection by inhibiting reproduction of harmful toxins.

– Drug O/D PCP, Cocaine, Meth

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Heat Stroke

• Treatment of heat stroke– If in doubt treat for heat stroke!!

– remove the patient from the environment and promote rapid cooling

– evaporate cooling by spraying tepid water over the patient while transporting

Heat Stroke

• Treatment (continued)– Evaluate the ABCs, administer supplemental oxygen,

and be prepared to intubate.– Cool as rapidly as possible by the most expeditious

means available body temperature to 102°°.– Start an IV line, give normal saline carefully may

lead to pulmonary edema– Check the blood glucose level.– Monitor cardiac rhythm.– Be prepared to treat seizures.

Heat Stroke

• Treatment (continued)– Check the blood glucose level.

– Monitor cardiac rhythm.

– Be prepared to treat seizures.

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Post Test

1. The thermal regulation center is located in the?

a. Heart

b. Kidneys

c. Lungs

d. Hypothalamus

Post Test

2. Name four ways that our body loses heat?

a) _____________________

b) _____________________

c) _____________________

d) _____________________

Post Test

3. Signs and symptoms of severe hypothermia include:

a. Severe shivering

b. Tachycardia

c. Pulseless

d. Tachypnea

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Post Test

4. The body’s normal reaction to heat exhaustion is to start to shiver to compensate.

a. True

b. False

Post Test

5. Classic heat stroke usually occurs in all of the following populations except:

a. Geriatrics

b. Pediatrics

c. Immune suppressed

d. Healthy adult

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