CCP 332 Environmental Emergencies 🥶 Flashcards
define thermoregulation
the ability of humans and other mammalian species to internally regulate their body temperature
define Primary (accidental) hypothermia
Caused by exposure and not secondary to infection, metabolic derangement, endocrinopathy, or trauma
mild hypothermia “Stage 1 Hypothermia”
HT-1
- Conscious
- Shivering
- Vital Signs present
- Temp Celcius 32-35°C
moderate hypothermia “Stage 2 Hypothermia”
HT-2
- Altered Mental Status/decreased LOC
- +- Shivering
- Bradycardia +- hypotension
- Temp Celcius 29-31°C
severe hypothermia “Stage 3 Hypothermia”
HT-3
- Unconscious
- not shivering
- Hypotension/Bradycardia
- Acid/base issues
- High risk for VF
- Temp Celcius <29°C
Cardiac arrest “Stage 4 Hypothermia”
HT-4
- Unconscious
- not shivering
- Vital Signs ABSENT
- Temp Celcius <29°C
Mild Hypothermia (HT-I)
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- Temperature between 32-35°C (89-95°F):
- Associated with shivering, cold diuresis, amnesia, ataxia.
- Remove from the cold environment and use passive rewarming.
Tachycardia, tachypnea, shivering, impaired cognition, memory, and coordination.
Moderate Hypothermia (HT-II)
- Temperature between 29-31°C
- Associated with dysrhythmias, change in mental status.
- Use active external rewarming.
Bradycardia, bradypnea, hypotension, no shivering, stupor, atrial arrhythmias, sluggish reflexes.
Severe/profound Hypothermia (HT-III or IV)
- Temperature less than 29°C
- Associated with hemodynamic instability or cardiac arrest, coma mimicking brain death.
- Treated with ECLS. Alternatively, use invasive rewarming.
Marked hypotension or ventricular dysrhythmia, unresponsive, loss of reflexes, possible rales (pulmonary edema).
describe the process of “passive rewarming” for mild-moderate hypothermia
- Remove cold/wet clothing.
- Provide oral glucose when appropriate to support shivering.
- Insulate, preferably with warm blankets
- If IV fluids are indicated, use warmed fluids.
describe the process of “active rewarming” for moderate-severe hypothermia
- Perform the mild hypothermia interventions
- IV fluids via a warming circuit (Buddy-Lite). fluids can also be microwaved at high power for 2 min
- Apply external rewarming devices (eg, Bair Hugger), water circulation pads (eg, Arctic Sun), radiant heat lamps, or hot blankets (Ready-Heat)
- heat packs packed into groin, neck, and axilla
- In MV patients, use 100% humidification and a circuit heater
- In spontaneously breathing patients, heated humidification may be provided via CPAP. This provides an additional heat gain of up to 10-30%/hr
describe the process of “minimal invasive rewarming” for moderate-severe hypothermia
- Perform the mild and moderate hypothermia interventions AND the following
- Avoid physical perturbations that may precipitate ventricular arrhythmias
- Consider intubation
- Place an esophageal temperature probe in intubated patients.
- Place a 3-way urinary catheter for continuous irrigation of 42°C (107°F) fluids.
- Use intravascular rewarming catheters such as the Alsius/Zoll ICY catheters, which are commonly used for post-arrest TTM protocols
At what point does a patient count as “warm and dead” per established guidelines
core temp 32°C
Contraindications to transfer for ECLS in the severely hypothermic patient
- Core Temperature of 32°C (90°F) or greater
- Noncompressible chest
- Potassium level >12 mEq/L
- DNR status
- Clear primary cause of arrest that is not hypothermia, such as:
- Witnessed arrest prior to hypothermia
- Avalanche burial for less than 35 min or with a snow–packed airway
- Drowning (head underwater prior to cooling)
describe the process of “full invasive rewarming” for severe hypothermia
all of the above interventions plus:
- Ongoing ACLS resuscitation
- thoracic lavage or peritoneal lavage as temporizing measure to bridge to ECLS
- continuous arteriovenous rewarming (CAVR)
- ECLS/ECMO
Cardiovascular and ECG changes associated with hypothermia
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- In initial phases of cold stress and mild hypothermia, autonomic stimulation → peripheral vasodilation + mild tachycardia, resulting in ↑ CO + MAP
- As temperature continues to lower, ↓ inotropy + ↓ chronotropy occur despite autonomic input.
- Depolarization and the conduction system are slowed → Osborn J waves
- Diastolic dysfunction occurs, → increased CVP + PCWP → pulmonary edema
- Conduction system dysfunction occurs → lengthening of PR interval, QRS complex, and QTc interval → dysrhythmias
- temperatures less than 32°C → atrial ectopy/A-Fib
- temperatures less than 25°C → VTach
- temperatures less than 22°C → VFib
- temperatures less than 20°C → Asystole
4 types of heat transmission
Radiation
Convection
Conduction
Evaporation
