environmental emergencies Flashcards
1
Q
introduction
A
- NOAA reports 175-200 US deaths each year from heat related disorders
- NCHS reports average 371 deaths per year between 1979 and 1997
- several comorbidities greatly affect morbidity and mortality:
- underlying pathology
- age
- exposure type and duration
2
Q
temperature management
A
- balancing heat loss with heat production:
- hyperthermic conditions
- hypothermic conditions
3
Q
human body temperature
A
- maintained between 35.6 and 37.8
- 98.6 F
- at elevated temperatures:
- enzymes cause to function
- proteins denature
- cellular metabolism is hampered
- “critical thermal maximum” - core temperature >43C
4
Q
hypothalamus
A
- part of diencephalon
- responsible for:
- temperature regulation
- preoptic region of hypothalamus
- water balance
- set point for thermoregulation
5
Q
factors affecting temperature regulation
A
- pediatrics- do not thermoregulate like adults
- elderly- sicker, comorbidities
- patient age
- patient health- comorbidities
- medications
- exposure time
- BSA/weight ratio
6
Q
heat production
A
- most heat production from deep organs:
- liver
- brain
- heart
- skeletal muscles during activity
- circulatory system transfers heat throughout body- transfers heat from organs to tissues
7
Q
heat loss
A
- cooling- heat transferred from deep structures to skin
- blood vessels in skin dilate -> fill with warm blood and heat transfers to skin
- heat lost from skin to surrounding environment
- rate of heat loss determined by rate of :
- heat condition from deep tissues
- heat transfer from skin to environment
8
Q
mechanisms of heat loss: radiation
A
- heat loss in form of infrared radiation
- 60% of heat loss in unclothed person via radiation
- greater the temperature difference between body and environment, greater the rate of loss
- sun rays
9
Q
convection
A
- conductive heat loss to air flowing over body
- greater the air flow over the body, greater the heat loss
- about 15% of heat loss
10
Q
conduction
A
- loss of body heat via direct transfer through physical contact
- ineffective way to exchange heat
- about 3% of total heat loss
11
Q
evaporation
A
- water changes from liquid to vapor when it evaporates
- water must be heated to turn to vapor
- evaporation results in net heat loss
- insensible water loss
- unnoticed water loss
- evaporation without sweating
- respiratory tract
- evaporation is more effective at low humidity
- water cannot evaporate in high humidity
12
Q
involuntary heat loss methods
A
- activation of peripheral and/or central chemoreceptors results in:
- activation of sweat glands, production of sweat
- activation usually occurs at >32.8 C
- capillary dilation
- inhibition of mechanisms that produce heat
- shivering, chemical thermogenesis
13
Q
voluntary heat loss methods
A
- limit- limit activity
- move- move to cool environment
- clothing- remove clothing -> cause return to hypothalamic “set point”
14
Q
involuntary heat gain methods
A
- constriction of peripheral blood vessels- shunt blood away from areas that are not as important -> goes towards core
- piloerection- goose bumps
- release of thyroxine from thyroid gland- metabolism
- increased production and release of epinephrine
- shivering, increased BMR
- unopposed increase of BMR can raise body temperature 1.1 C/hr
15
Q
voluntary heat production methods
A
- add heavy clothing
- increase activity
- reduce exposed skin
16
Q
hyperthermia categories
A
- elevated body temperature
- heat tetany
- heat cramps
- heat exhaustion
- heat syncope
- heat stroke
17
Q
heat tetany
A
- hyperventilation a common cooling mechanism -> decreased CO2
- like panting in a dog
- leads to respiratory alkalosis
- carpopedal spasms possible- paresthesia (pins and needles) due to low CO2
- self-limiting, corrects when hyperventilation stops -> give brown paper bag or put oxygen mask on but dont turn it on
18
Q
heat cramps
A
- brief, painful muscle cramps (frequent complication of heat exhaustion)
- common in athletes, outdoor workers
- dehydration
- salt depletion, electrolyte abnormalities common
- treatment symptomatic
19
Q
heat exhaustion
A
- ill define syndrome
- associated with high air temperatures, excessive sweating
- those at risk: athletes, outdoor workers, elderly, young
- signs and symptoms include:
- dizziness, fatigue, irritability, anxiety
- headache, chills, nausea, vomiting
- heat cramps
- tachycardia, hyperventilation, hypotension, syncope
- treatment- remove patient from environment and replace fluids and electrolytes
20
Q
heat syncope
A
- usually occurs in those unacclimated to heat
- form of postural hypotension- massive peripheral vasodilation and dehydration
- body needs to reset
- fluids
- hypotension
- treatment symptomatic
21
Q
heat stroke
A
- define by:
- core temperature higher than 40.5C
- anhidrosis- may or may not be present
- altered mental status
- can be fatal
- represents total failure of thermal regulatory mechanisms - can be rapidly fatal
- two categories: exertional and Non-exertional
22
Q
heat stroke: metabolic breakdown, irreversible organ death at 43C
A
- critical thermal maximum
- cellular respiration impaired
- increased cellular membrane permeability
- enhanced heat production
- protein denaturing
- tissue necrosis
23
Q
heat stroke: signs and symptoms
A
- apertured mental status, altered LOC, unconsciousness
- anhydrosis- (stop sweating) may or may not be present
- hyperventilation, hypoventilation, tachycardia
- pulmonary edema
- seizures
- posturing
- slurred speech
24
Q
heat stroke management
A
- support ABCs
- replace fluids and electrolytes
- give fluids judiciously
- hypotension may correct once peripheral vasodilation occurs with cooling
- monitor hydration
- *placement of indwelling thermometer- rectal or esophageal
- *immediate cooling of temperature of 40C:
- cold packs
- cold water immersion
- evaporative cooling
- lukewarm water
- thoracic, peritoneal lavage
- pharmacologic intervention
25
Q
pharmacological intervention of heat stroke
A
- administer lorazepam, chlorpromazine
- control shivering
26
Q
when rhabdomyolysis is present in heat stroke
A
- increase GFR
- hydrate aggressively
- give mannitol
- alkalize urine
- treat with sodium bicarbonate
27
Q
hypothermic categories
A
- central- classic hypothermia
- peripheral- frostbite
28
Q
hypothermia
A
- core temperature <35C
- severe hypothermia- core temp <32.2C (dont need to know numbers)
- speed on onset influenced by:
- temperature
- degree of exposure
- wind chill factor
- comorbidities
29
Q
mild hypothermia
A
- activation of heat conserving and generating mechanisms
- heart rate, blood pressure, CO rise
- patients typical exhibit:
- shivering
- lethargy
- lack of coordination
- loss of fine motor control
- cool, dry, pale skin
30
Q
severe hypothermia
A
- metabolism slows
- heart rate, blood pressure, CO fall
- patients typically exhibit:
- lack of shivering
- loss of voluntary muscle control
- hypotension
- undetectable pulse and BP
- cardiac arrest
- ECG abnormalities
- organs shut down
- everything is slow
31
Q
signs and symptoms of hypothermia
A
- decreased mental status
- mood changes
- change in vital signs
- breathing rapid at first -> shallow, slow, absent
- pulse rapid at first -> slow barely palpable, absent
- skin red -> pale, cyanotic, cold to touch
- slowly responding pupils
- low to absent BP
- decreased motor and sensory function
32
Q
general management of hypothermia
A
- depend on severity
- dry patients, protect from additional heat loss
- avoid rough handling
- address cardiac irritability
- measure, monitor core body temperature
- warm
- gradually** warm -> otherwise everything will hit all at once*
33
Q
management of mild hypothermia
A
- exercise active external methods
- use blankets
- apply heat packs
- conduct warm water immersion
- administer warm, humidified oxygen
34
Q
management of severe hypothermia
A
- use external and internal methods
- administer warm IV fluids- 45-65 C
- conduct thoracic, abdominal lavage -> for hypothermic patient in cardiac arrest
- attempt resuscitation until core body temperature rises above 32C
- follow ACLS protocol
35
Q
frostbite pathophysiology
A
- freezing of the distal extremities
- cold exposure causes:
- formation of ice crystals in the extracellular compartment
- abnormal cell wall permeability
- capillary damage
- pH changes
36
Q
frostbite management
A
- rewarm affected area
- defer if refreezing possible
- warm bath 39-42C
- administer analgesics:
- morphine fentanyl
37
Q
frostbite classifications*
A
- first degree
- second degree- fluid blisters start forming *
- third degree- blood-filled blisters *
- fourth degree
- know the difference between 2nd and 3rd degree
38
Q
first degree frostbite
A
- superficial freezing
- edema
- skin with waxy appearance
- no blisters or vesicles
39
Q
second degree frostbite
A
- blister formation with clear fluid
- erythema
- edema
40
Q
third degree frostbite
A
-blood filled blisters
41
Q
fourth degree frostbite
A
- full thickness injury
- death of dermal tissue
- extension into muscles, tendons, bones
42
Q
ongoing management of heat stroke, hypovolemic shock
A
- IV access- NS bolus 500 ml
- continuous cardiac monitoring
- immediate cooling- move to cool environment/shade, immerse in cold water or fan with cool mist, cold IV fluids, ice packs
- use caution to avoid induction of shivering
- benzodiazepines can be used if necessary
- transport to facility with ICU-level care
- fluid replacement (from losses through sweating)
- rapid cooling
- cardiac monitoring
- avoidance of overhydration, which can lead to pulmonary edema
- readiness for seizures
43
Q
conclusion
A
- a balance of heat production and heat loss contribute to core body temp
- metabolic rate and skeletal muscle activity compose the main elements of heat production
- conduction, convection, evaporation, and radiation compose the main elements of heat loss
- medications, pre-existing medical conditions, activity level, ambient temperature, and humidity are main factors influencing body heat balance
- a number of factors contribute to environmental emergencies
- What are the various methods of heat loss?
- Hypothermia and hyperthermia are true medical emergencies
- What are the various hyperthermic categories?
- Management according to the symptoms can help save your patients life
- Role of the hypothalamus?
