1. Management of Hypothermia

2. I wonder where Shirley is with my drink?
Humans are warm-blooded mammals who maintain a constant body temperature
(EUTHERMIA- producing or creating heat or warmth)

3. The human body maintains homeostasis of the body temperature
In Other Words…We have our own built in Heat-conserving Mechanisms

4. What is Hypothermia?
•CLASSIC DEFINITION: A state of low body temperature, specifically a low CORE temperature (< 35º C or < 95º F). • ALTERNATIVE DEFINITION: It is best defined as the unintentional decrease of around 2º C (3.6º F) from the “normal” CORE temperature
Heat loss results from:
Conduction
Convection
Radiation
Evaporation
Respiration

5. CONDUCTION Conduction:
Heat loss occurs due to direct contact of the body with a cooler object.
Heat flows from higher temperature matter to lower temperature matter.
EXAMPLES: Sitting on a cold rock, touching cold metal or falling into cold water.

6. Where is that women with my drink?
CONVECTION
Where is that women with my drink?
Convection:
Heat loss occurs due to air currents passing over the body.
Heat must first be conducted to the air before convection can occur.
EXAMPLES: When cold air or water circulates across the body, such as a cold wind (wind chill factor)

7. RADIATION
Radiation:
Heat loss results from infrared rays.
All objects not at absolute zero will radiate heat to the atmosphere.
A great deal of heat can be radiated out from your uncovered head
Radiation occurs when heat escapes from your body into the air in much the same way as heat radiates out from a fire

8. EVAPORATION Evaporation:
Heat loss occurs as water evaporates from the skin.
Heat loss occurs as water evaporates from the lungs during respiration.
Heat loss by evaporation occurs when moisture on the surface of the body becomes airborne
Note: This does not require a hot day to occur and the moisture can come from sweat, rain, snow or falling into a lake or river.

9. RESPIRATION
Respiration:
Respiration combines the heat loss mechanisms of convection, radiation, and evaporation.
Expired air is normally 98.6 degrees F. and 100% humidified
If the air we breathe is colder than body temperature, our body heats the air to body temperature before it reaches the lungs. When we breathe out, much of that heat is lost into the air.

10. What is the CORE temperature?
Core Temperature is:
The deep internal temperature of humans

11. A Tympanic thermometers are inaccurate below 35 ̊ C or 95̊ F
How is the CORE temperature measured?
A rectal temperature is a good index of CORE temperature. Although can be falsely lowered by frozen feces
Oral temperature is an excellent index of CORE temperature, provided the mouth is kept closed. Standard oral thermometers do not record below 35 ̊ C or 96̊ F
A Tympanic thermometers are inaccurate below 35 ̊ C or 95̊ F

12. Vasoconstriction
Vasoconstriction of blood vessels in the skin. When blood vessels constrict, the flow of blood is restricted or decreased, thus, retaining body heat or increasing vascular resistance. It is stimulated through activation of the sympathetic nervous system. It’s what causes pale, cool skin because less blood reaches the surface.

13. Goose Bumps
Also known as Philomotor Reflex: In cold situations, the rising hair traps air between the hairs and skin, creating insulation and warmth
Caused by sympathetic stimulation of arrector pili muscles. The small muscles attached to hair follicles in mammals.

14. Increased heat production:
Shivering
It is a bodily function in response to early hypothermia in warm-blooded animals.
. Muscle groups around the vital organs begin to shake in small movements in an attempt to create warmth by expending energy.

15. Predisposing Factors to Hypothermia:
Patient Age
Patient Health
Medications
Prolonged or Intense Exposure
Co-existing Weather Conditions

16. OLDER AGE: People age 65 and older are more vulnerable to hypothermia for a number of reasons. The body's ability to regulate temperature and to sense cold may lessen with age. Older people are also more likely to have a medical condition that affects temperature regulation. Some older adults may not be able to communicate when they are cold or may not be mobile enough to get to a warm location.

17. VERY YOUNG: Children lose heat faster than adults do
VERY YOUNG: Children lose heat faster than adults do. Children have a larger head-to-body ratio than adults do, making them more prone to heat loss through the head. Children may also ignore the cold because they're having too much fun to think about it. And they may not have the judgment to dress properly in cold weather or to get out of the cold when they should. Infants may have a special problem with the cold because they have less efficient mechanisms for generating heat.

18. MENTAL PROBLEMS: People with a mental illness, dementia or another condition that interferes with judgment may not dress appropriately for the weather or understand the risk of cold weather. People with dementia may wander from home or get lost easily, making them more likely to be stranded outside in cold or wet weather.

19. CERTAIN MEDICAL CONDITIONS: Some health disorders affect your body's ability to regulate body temperature. Examples include underactive thyroid (hypothyroidism), poor nutrition, stroke, severe arthritis, Parkinson's disease, trauma, spinal cord injuries, burns, disorders that affect sensation in your extremities (for example, nerve damage in the feet of people with diabetes), dehydration, and any condition that limits activity or restrains the normal flow of blood.

20. MEDICATIONS: A number of drugs, including certain antidepressants, antipsychotics and sedatives, can change the body's ability to regulate its temperature. EXAMPLES: Prozac, Zoloft, Paxil, Luvox, Celexa, and Lexapro
They can both impair central thermoregulation and also inhibit peripheral vasoconstriction in response to cold by their alpha‐blocking activity.
EXAMPLES: Prozac, Zoloft, Paxil, Luvox, Celexa, and Lexapro

21. ALCOHOL AND DRUG USE: Alcohol may make your body feel warm and fuzzy inside, but it causes your blood vessels to dilate, or expand, resulting in more rapid heat loss from the surface of your skin. The use of alcohol or recreational drugs can affect your judgment about the need to get inside or wear warm clothes in cold weather conditions. If a person is intoxicated and passes out in cold weather, he or she is more likely to develop hypothermia.

22. Coexisting Weather Conditions:
High humidity, brisk winds, and accompanying rain can all magnify the effect of cold exposure on the body by accelerating heat loss from the skin.

23. Degrees of Hypothermia
Mild– Core temperature > 90 degrees F (32 degrees C)
Severe– Core temperature < 90 degrees F (32 degrees C)
The commonly accepted average core body temperature
(taken internally) is 98.6

24. Signs and Symptoms MILD Hypothermia: Lethargy Shivering
Lack of Coordination
Pale, cold, dry skin
Early rise in blood pressure, heart, and respiratory rates.
This does not require a hot day to occur and the moisture can come from sweat, rain, snow or falling into a lake or river.

25. Signs and Symptoms SEVERE Hypothermia: No shivering
Heart rhythm problems
Cardiac arrest
Loss of voluntary muscle control
Low blood pressure
Undetectable pulse and respirations

26. ASSESSMENT
Find out how long your patient has been exposed to the cold environment
Focus on the severity of hypothermia.
Assess the areas of the body directly affected by cold exposure.
Assess the degree and extent of damage.
Pay special attention to skin temperatures, textures, and turgor.
Rhabdomyolysis common with
severe hypothermia

27. Signs and Symptoms:  
Use mental status as your primary diagnostic to quickly determine how serious the hypothermia has become. Check the blood glucose; shivering causes glucose to be used up quickly.  Checking a pulse is a lot harder in hypothermic patients due to peripheral vasoconstriction, so take at least 30 seconds to a minute to feel for a pulse.

28. IMMEDIATELY REQUEST AIR TRANSPORT IF APPLICABLE

29. ASSESSMENT
When the patient has moderate or severe hypothermia, never try to actively re-warm the patient.
Active re-warming should be reserved for an appropriate facility.
The goal is to prevent further heat loss.(Passive re-warming only)
Remove wet clothing, cover with a blanket, and transport.

30. COLD WATER DROWNINGS OR NEAR DROWNINGS
When a person falls into cold water the body
temperature rapidly begins to fall.
Once hypothermia sets in it causes intense vagal
stimulation which results in severe bradycardia or
asystole. Any sudden movements to the
“near drowning” patient including
manipulation of the airway can cause cardiac arrest.

31. The initial problem that occurs is hypoxia
The initial problem that occurs is hypoxia. The victim becomes confused, then lethargic and eventually unconscious.
Patients often have reported that they experience a “high”, describing the phase as being “pleasant” , in that they no longer care what happened to them and “give-up”.

32. Treatment Treatment for Hypothermia: 1. Remove wet garments
2. Protect against further heat loss and wind chill Maintain patient in horizontal position 4. Avoid rough handling. 5. Monitor the core temperature.
6. Monitor the cardiac rhythm.

33. Core temp Condition °F °C
98-95
37-35
Cold Pale skin The patient is alert, shivering
Poor muscle coordination. Rapid breathing Rapid heart rate.
95-90
35-32
Cold, waxy skin. Puffy face, possibly pink. No shivering.
Confusion. Muscle rigidity. Slow heart rate.
90-86
32-30
Dialated pupils. Diminished reflexes. Stupor or coma.
Rigid muscles.. Slow breathing rate. Hypotension. Slow heart rate
86-82
30-28
Fixed dilated pupils. Coma. Flaccid muscles.
Slow respiration. Slow or rapid heart rate. V-fib, Possible cardiac arrest.
82-68
28-20
Cyanosis. Fixed, dilated pupils. Unresponsive.
Barely detectable vital signs. Irregular pulse. Cardiac arrest.

34. BE GENTLE
When you're helping a person with hypothermia, handle him or her gently.
Limit movements to only those that are necessary.
Don't massage or rub the person. Excessive, vigorous or jarring movements may trigger cardiac arrest.

35. If the patient is alert, shivering, responds appropriately, and the core body temperature is between 90°F to 95°F, then the hypothermia is mild.
Apply heat packs or hot water bottles to the groin, axillary, and cervical regions.
Re-warm the patient slowly.
Give warm fluids by mouth.

36. Re-warming in the field
With frostnip, contact with a warm object may be all that is needed.
With immersion foot, remove wet shoes, boots, and socks, and re-warm the foot gradually.
With a late or deep cold injury, do not apply heat or re-warm the part.

37. Hypothermia results in decreased depolarization of cardiac pacemaker cells, causing bradycardia. Since this bradycardia is not vagally mediated, it can be refractory to standard therapies such as atropine. Mean arterial pressure and cardiac output decrease, therefore the J or Osborne waves. Due to the peripheral vasoconstriction vasoconstrictors won’t work; drugs are unlikely to be distributed to the central circulation, they therefore will accumulate in periphery and will have toxic effect when circulation resumed.

38. ECG changes seen in hypothermia:
“J” or Osborne Waves
Prolongation of first the PR interval, then the QRS, then the QT interval.
J waves (also called Osborne waves) can occur at any temperature < 32.3º C (90º F).
Most frequently seen in Leads II and V6.
The size of the J waves increase with temperature depression.

39. SIGNIFICANCE OF OSBORN WAVES
Osborn waves observed in HYPOTHERMIA situations have been shown to be linked to ventricular fibrillation.
In the initial stages of hypothermia, a sinus tachycardia develops as part of the general stress reaction. As the temperature drops below 90°F, a sinus bradycardia follows, associated with progressive prolongation of the PR interval, QRS complex, and QT interval.
Most patients who die during active re-warming die from ventricular fibrillation.

40. Re-Warming Application of external heat in the
pre-hospital setting is usually not effective and not recommended because:
More heat displacement is required than generally possible in the pre-hospital setting.
Application of external heat may cause
“re-warming shock.”
Most patients who die during active rewarming die from ventricular fibrillation.

41. Re-WARMING SHOCK Occurs due to peripheral reflex vasodilation.
Causes the return of cooled blood and metabolic acids from the extremities.
May cause a paradoxical afterdrop in the core temperature further worsening hypothermia
The afterdrop phenomenon is that as peripheral tissues are warmed, vasodilation allows cooler blood in the extremities to circulate back into the body core. Some believe that afterdrop is most likely to occur in patients with frostbite or long-standing hypothermia.

42. Re-Warming Shock- Can be prevented in the
pre-hospital setting by using warmed IV fluids during active re-warming.
Benefits of IV Fluid Warming:
Maintains euthermia (creating heat or warmth)
Increases patient comfort
Prevents shivering

43. Cardiac Arrest
Resuscitation of cardiac arrest due to hypothermia is only successful when the patient is being re-warmed.
The hypothermic cardiac arrest patient is not DEAD until he is WARM and DEAD!

44. IN CONCLUSION:
Pre-hospital management focuses on preventing further heat loss, re-warming the body core temperature, and avoiding precipitating ventricular fibrillation or another malignant cardiac rhythms. Conscious patients can develop ventricular fibrillation suddenly; pre-hospital EMS, should avoid inadvertent jerky movement of severely hypothermic patients. Patients who develop hypothermia-induced dysrhythmia in the field may be beyond resuscitation.

45. Generally, defibrillation is ineffective as well as both cardiac pacing and atropine for bradyarrhythmia.
Lidocaine is also found to be ineffective in preventing hypothermia-induced ventricular dysrhythmias.
Initiate CPR until rescuers can begin active re-warming and perform successful defibrillation.

46. SUMMARY Hypothermia can be either a local or a systemic problem.
Local cold injuries include frostbite, frostnip, and immersion foot.
The key to treating hypothermic patients is to stabilize vital functions and prevent further heat loss.

47. SUMMARY
Do not consider a patient dead until he or she is “warm and dead.”
KEEP WORKING
Pulses are harder to detect in hypothermia because the body is shutting down blood flow outside the core. Take up to 1 minute when feeling for a pulse.
Medications may be ineffective.
Treatment primarily involves removing the patient from the cold environment, and initiating re-warming techniques.