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
