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Hypothermia

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by

Heather Berryman

on 21 May 2015

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Transcript of Hypothermia

Hypothermia
Introduction
Frostbite is the freezing of tissues which can lead to permanent loss of sensation or tissue death (gangrene) if there is permanent damage to blood vessels. It most commonly occurs in distal extremities farthest from the heart as well as any exposed areas such as the nose, ears and cheeks.
Frostbite
Pathology
Shivering is likely the first thing you'll notice as the temperature starts to drop because it's your body's automatic defense against cold temperature — an attempt to warm itself.
Manifestations
Etiology
Shivering
Dizziness
Hunger
Nausea
Tachypnea
Dysarthria (Trouble speaking)
Slight confusion
Loss of judgment and reasoning
Lack of coordination
Cold and pale skin
Lethargy
Tachycardia
Signs of Mild Hypothermia
Cessation of shivering
Clumsiness or lack of coordination
Pronounced dysarthia
Confusion and poor decision-making, such as trying to remove warm clothes
Extreme fatigue
Lack of concern about one's condition
Progressive loss of consciousness...this can lead to coma
Bradycardia coupled with a weak and thready pulse
Slow, shallow breathing
Pallor of the skin
Dilated pupils
Decreased gag reflex...increased risk of aspiration
Hyporeflexia
Signs of moderate to severe hypothermia
At or below 0 °C (32 °F), blood vessels close to the skin start to constrict and blood is shunted away from the extremities in order to preserve core body temperature. This protective strategy can reduce blood flow and eventually lead to the freezing and death of tissue in the affected areas.
Stages of Frostbite
First degree- aka “frostnip”- only the surface of the skin is affected and there is usually no long-term damage.
Second degree- aka “superficial frostbite”-frozen crystals may occur superficially but deeper tissues are not affected; there is usually no long-term affects but blistering may occur after warming.
Third and fourth degrees- aka “deep frostbite”- deeper tissues including the muscles, tendons, blood vessels, and nerves are all affected. The use of the area is temporarily lost and there can be permanent loss of sensation or tissue death (gangrene).
The first manifestation is tingling in the affected area followed by pallor. Numbness occurs. The tissues eventually become hard and stiff changing from a white pallor to a blue colour.

When rewarming occurs the area may become erythemic, painful, warm to the touch, and blistered. If tissue death has occurred then the tissue may appear black.

Initial treatment includes rewarming areas in a water bath of 40C- wet heat. The quicker the tissue is warmed the less damage results. Heaters or other forms of dry heat should not be used as these can cause burns or heat the area unevenly. Avoid rubbing the skin as this can cause more damage. The limb can be elevated above the level of the heart to decrease inflammation.
If gangrene has occurred then there is permanent tissue death. This will require careful debridement of the necrotic tissue. In some cases of deep tissue necrosis amputation of the affected area may be the only option.
After healing has occurred there can be:
Permanent loss of sensation
Paresthesias
Increased sensitivity to both hot and cold temperatures
Increased risk for frostbite again.
High Risk Populations
• Older age.
• Very young age.
• Mental illness
• Alcohol and drug use
• Certain medical conditions
• Medications

Diagnosis
Treatment
Older Adults
Over 50% of recorded hypothermia deaths occur in individuals over 65 years of age

Hypothalamic insult
Endocrine changes
Malnutrition, hypoglycemia, neuromuscular insufficiencies.

Altered thermoregulation
Comorbidities
In addition to those affecting thermoregulation.....
also mental illnesses such as dementia where judgment is altered

Also, comorbidities often lead to.....
Polypharmacy
Particularly threatening ones:
Tricyclic antidepressants
Neuroleptics
Beta blockers
Sedatives
Narcotics
Others
• Decreased activity levels
• Altered sensory perception
• Inability or reduced ability to communicate physiologic needs

Often increased mortality partially due to later detection
Elder hypothermia often has an atypical presentation where the initial signs are a decreased level of consciousness, which people may consider normal behavior related to aging
Pediatrics
THANK YOU!
Facts:
Increased surface area to volume ratio
Infants are at particularly high risk due to less effective thermoregulation
Altered judgment

Wind, wet and cold are the key factors. Wind can chill the body as air moves over it. Water rapidly absorbs body heat; wet clothing is a common cause of hypothermia, and casualties in lakes and rivers are often due to hypothermia, not drowning. Cold air cools down the body - but it does not have to be frigid; hypothermia can happen at under 10 C, so it's a threat even with above-average winter temperatures.


RE-CAP:
The World Health Organization published (2001) that one of the biggest problems neonates face is hypothermia. WHO estimates that 18% to 42% of worldwide annual infant deaths are caused by hypothermia.

Water temperature, body size, body fat percentage and movement in the water each play a part in cold-water survival. Small people cool faster than large people; children cool faster than adults.

Life jackets can help you survive cold water. They let you float without using energy while insulating your body from cold water.

NEVER rub a frostbitten body part- it could cause gangrene, or tissue death due to lack of oxygen.

Alcohol lowers the core temperature of your body, so is actually harmful to an individual who is at risk for hypothermia.



Canada's Inuit People
The Inuit are aboriginal people
who have inhabited the Arctic
region of Canada since 1500AD.
They have adapted to live with the
short, cool summers and the harsh,
cold winters of the far north.
Diagnosis of hypothermia is based on core temperature and clinical presentation. It is divided into 3 Zones:
Mild
,
Moderate
, and
Severe
.
It is important to use a special low temperature reading rectal thermometer as many thermometers do not read below 34°C.
Inuit Life Saving Techniques
Mild Hypothermia:



Initial excitation phase to combat cold
•Hypertension
•Shivering
•Tachycardia
•Tachypnea
•Vasoconstriction
With time and onset of fatigue
•Apathy
•Ataxia
•Cold diureses
•Hypovelemia
•Impaired judgement
Lewis Hunting Response:
Process of alternating vasoconstriction and vasodilation in peripheral blood vessels with irregular, repeated sequences.
Hypothermia is a medical emergency that occurs when your body loses heat faster than it can produce heat, causing a dangerously low body temperature.
Normal body temperature is around 37 C. Hypothermia occurs as your body temperature passes below 35 C.
Temperature 32.2-35°C
Clinical Presentation:
Moderate Hypothermia
Temperature: 28-32.2°C
Clinical Presentations:
Atrial dysarhythmias
Decreased heart rate
Decreased LOC
Decreased Resp rate
Dialted pupils
Diminished gag reflex
Extinction of shivering
Hyporeflexia
Hypotension
Body Loses Heat In 5 Ways
Respiration
Evaporation
Conduction
Radiation
Convection
Severe Hypothermia
Temperature: < 28°
Clinical Presentations:
Apnea
Coma
Non reactive pupils
Oliguria
Pulmonary edema
Ventricular dysrhythmias
Exposure and Exhaustion
The moment your body begins to lose heat faster than it produces it, you
are undergoing exposure. Two things happen:
1. You voluntarily exercise to stay warm.
2. Your body makes involuntary adjustments to preserve normal temperature
in the vital organs, and you start shivering.
Either response drains your energy reserves. The only way to stop the
drain is to reduce the degree of exposure.

When body temperature drops, the bodies multiple systems loose normal function; cardiovascular and respiratory systems, nerve conduction, mental acuity, neuromuscular reaction time, and metabolic rate. Hypothermia can eventually lead to complete failure of the cardiovascular and respiratory systems, leading to death.
Treatment focuses on preventing further heart loss, re-warming the bodies core temperature, and avoiding precipitating ventricular fibrillation or other malignant cardiac rhythm. The body should be heated at a rate of 0.2-0.5°C per hour.
Water
Robs the body of heat 32 times faster than cold air
Numbs Extremities
Swimming and treading causes the body to loose heat faster
Risk of Drowning
Water 10 degrees C can lead to death in 1 hour
Near freezing temperatures can causes death in 15 minutes
Decreased ambient temperature is sensed by the thermoreceptors of the skin and subcutaneous tissues

The resulting regional vasoconstriction signals to the hypothalamus to release TSH and ACTH

The thyroid and adrenal glands then increase metabolism and thus heat production

The hypothalamus also increases heat production by promoting shivering

The renal blood flow and glomerular filtration rate decrease as well, resulting in natriuresis and diuresis with eventual hypovolemia

Slowed brain activity, breathing, and heart rate, confusion, fatigue
The Diving Reflex
Decreased temperature can trigger the diving reflex, which involves reflex vasoconstriction in visceral muscles; blood is shunted to essential organs
Things to avoid:
There are certain things you shouldn't do when helping someone with hypothermia because it may make the condition worse:
avoid unnecessary jerky movements
don't put the cold person into a hot bath
don't massage their limbs
don't use heating lamps
don't give them alcohol to drink
Trying to warm someone up yourself with hot water, massages, heat pads and heat lamps can cause the blood vessels in the arms and legs to open up too quickly.
If this happens, it can lead to a dramatic fall in blood pressure to the vital organs, potentially resulting in cardiac arrest and death.
Move the person indoors or somewhere warm as soon as possible.
Once the person is in a warm environment, carefully remove any wet clothing and dry them.
Warm the person using skin to skin contact, warm blankets, towels, or coats (whatever you have available), warming their head and torso first.
Encourage the person to shiver if they're capable of doing so.
If possible, give the person warm drinks (not alcohol) or high-energy foods, such as chocolate, to help warm them up.
Once the person's body temperature has increased, keep them warm and dry.

When your body temperature drops, your heart, nervous system and other organs can't work normally. Left untreated, hypothermia can eventually lead to complete failure of your heart and respiratory system and to death.
It is most often caused by exposure to cold weather or immersion in a cold body of water.
Medical interventions:

Treatment in the field:
In severe cases of hypothermia medical interventions may
be necessary. These include:
Airway rewarming with humidified oxygen at 40°C
Warming Intravenous fluids (preferably 5 percent dextrose and normal saline) should be heated to 40°C to 45°C.
Body cavity lavage
Extra corporeal blood warming
32.3-35 degrees
Hypothermia can be considered:

Primary due to straightforward exposure to cold environments

Secondary due to disease or an environmental exposure coupled with another reason, such as intoxication

Intentional as in cardiac bypass or post-resuscitation therapeutic hypothermia
28-32.2 degrees
less than 28 degrees


Typical signs of hypothermia in an infant include:

Bright red and mottled skin colour
Skin that is cool to the touch
Unusually low energy
Periods of apneic breathing
A weak cry
Poor feeding
Hypothermia in Infants
Survival in the water:
Full transcript