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
how far does the rectal probe go up the neonate’s butt?
5cm
describe heat loss via “radiation”
- Radiation is similar to heat leaving a woodstove
- This normal process of heat moving away from the body usually occurs in air temperatures lower than 20°C
- The body loses 65% of its heat through radiation
- Core body tissues transfer heat in subcutaneous blood vessels which emit infrared rays from the skin surface to lose heat by radiation
describe heat loss via “Convection”
- Convection is similar to sitting in front of a fan or having the wind blow on you
- represents the transfer of heat from a body to MOVING molecules such as air or liquid
- The body normally loses 10% to 15% of its heat through convection
describe heat loss via “Conduction”
- Conduction is the type of heat loss u get from sleeping on the cold ground
- Conduction is the loss of molecular kinetic energy in the form of heat from the skin to the surroundings.
- Different mediums transfer heat by conduction at different rates. For example, the conductive transfer of water is 100x that of air (so heat can be lost from the body very quickly when it is placed in cold water)
describe heat loss via “Evaporation”
- Evaporation is heat loss of water from your skin if it is wet (sweating).
- Under normal circumstances Evaporation accounts for about 22% of heat loss.
- During intense exercise, the body loses 85% of its heat through sweating.
- The body depends on evaporation for heat dissipation when the environmental temperature is warmer than the skin or when convection and radiation are insufficient.
clinical features of Heat Cramps
- Muscle pain and spasm
- No signs of severe illness
- Predisposing factors: heavy sweating, dehydration, insufficient sodium intake
treatment of Heat Cramps
Hydration
Replace sodium losses
Relax, stretch, massage affected muscles
clinical features of Heat Syncope
- Pre-syncope or syncope
- No significantly elevated temp
- During or immediately after significant exertion or heat
exposure
treatment of Heat Syncope
- Remove from heat stress
- Horizontal position
- Mental status and symptoms should resolve quickly
clinical features of Heat Exhaustion
- Can’t maintain CO d/t significant exercise +/- heat stress
- Temp 38.3 – 40.0°C
- No significant CNS dysfunction
treatment of Heat Exhaustion
- Remove from exertion/heat
- Supine position
- Cooling measures
clinical features of Heat stroke
- Heat Stress
- Mod-severe CNS dysfunction
- Hyperthermia (usually >40.0°C)
- Risk of multi-organ dysfunction
treatment of Heat stroke
- Immediate rapid cooling
- Supportive care (IV hydration)
- Monitor for end-organ dysfunction
Henry’s Law
Amount of gas that will dissolve in a liquid at a given temperature is directly proportional to the partial pressure of that gas
Submersion definition
airway below surface of liquid
Immersion definition
airway above surface of liquid
Immersion syndrome definition
syncope resulting from cardiac dysrhythmias on sudden contact with water that is at least 5°C lower than body temperature
Drowning definition
A process resulting in primary respiratory impairment from submersion or immersion in a liquid medium
clinical features of Acute Mountain Sickness
- Recent ascent to >2500m (8000ft)
- Headache plus any 1 of: GI upset; General weakness/fatigue; Dizziness/lightheadedness; Sleeping difficulty
- Sx develop within hours
- Peak 24-48h
clinical features of High-Altitude Cerebral Edema (HACE)
- Typically >3000m
- Usually preceded by AMS
- Encephalopathic symptoms
– Ataxic gait
– Lassitude
– Progressive decline in cognitive function and LOC
Acute Mountain Sickness treatment
• Stop ascent, rest • Acetaminophen, ibuprofen for headache • Oxygen therapy • Acetazolamide – Stimulates resp center – Diuresis – Decreases nocturnal periodic breathing • Dexamethasone (moderate-severe sx)
High-Altitude Cerebral Edema (HACE) treatment
- Immediate descent
- Oxygen therapy
- Dexamethasone
- Hyperbaric therapy
clinical features of High-Altitude Pulmonary Edema (HAPE)
- Most common fatal manifestation of severe high-altitude illness
- Insidious 2-4d after ascent to ~>8000ft
- Dyspnea
- Fatigue
- Cough
- May progress to respiratory failure
High-Altitude Pulmonary Edema (HAPE) Treatment
- Immediate Descent
- Oxygen therapy
- Intubation and MV prn
- Nifedipine (pulmonary vasodilator)
- DO NOT treat as volume overloaded/CHF
Type 1 Decompression sickness (DCS I) clinical features
- pain in girdles and extremities
2. Involves skin, muscles, joints, lymphatics
Type 2 Decompression sickness (DCS II) clinical features
- Cerebral – altered LOC or non-specific focal deficits
- Spinal “bends”– Lumbar most common – pain, paresthesias, weakness, sensory loss, back and abdo pain
- Inner ear “staggers” – cochlear and vestibular symptons – N/V, vertigo, nystagmus, hearing loss
- Pulmonary ”chokes” – dyspnea, cough, chest pain
pathophysiology of pulmonary barotrauma 2nd to SCUBA diving
Too fast of an ascent or failure to exhale during ascent → Volume expansion of alveoli → alveolar rupture or hemorrhage
- Pneumothorax
- Pneumomediastinum/subcutaneous emphysema
- Pulmonary hemorrhage
