environmental illness Flashcards
temperature is regulated by
hypothalamus
body can tolerate hypothermic change of about
en bas de 5ºC
body can tolerate hyperthermic change of about
en haut de 3ºC
Body functions within narrow temperature range of about _°C on either side of 37C
3
mechanism of heat loss
convection
conduction
evaporation
radiation
what is convection
Air currents blowing across the body remove heat from body. (eg: windchill)
40% loss through head and neck
what is conduction
Direct heat exchange from one body surface to another. The second body can be air, solid, or a liquid
Whatever is in contact with the patient can remove heat if colder.
Can generally lose heat twice as fast through the _ than to the _
ground than the air
A person loses much more heat in the _ than _ of same temp
water than air
(ie: keep victim dry ; remove wet clothing)
what is evaporation
Changing from liquid to gas requires calories. A liquid that evaporates from the skin surface removes calories in the process.
During exercise evaporation accounts for as much as % of total heat loss in a hot/humid environment (% if hot/dry).
75, 90
what is radiation
Energy in the form of heat radiates in waves (Infra-red) through the air or other medium.
❑Patient heat is absorbed by cooler environment or nearby objects. (ie: warm air from lungs)
_ air ambient temp, _ heat loss via conduction, radiation, convection
increase, decrease
_ ambient temp, _ heat loss gradually by conduction, convection (worst in windy or wet environment)
decrease, increase
Wet Bulb & Black Globe temperature taken for minute at specific site
1
wet bulb + black globe green, yellow, red, black flag
<18 ºc green flag low risk
18-23ºc yellow flag, moderate risk
23-28ºC red flag, high risk
>28ºC black flag, extreme risk
heat stress prevention
Education
❑ On-site medical coverage with authority to
withdraw individuals
❑ Pre-season exam with appropriate info
❑ Optimal Hydration
Common for athletes to lose between _ lbs of sweat playing a game
5-8
Losses as little as % of body weight can impair performance / ↑ fatigue (eg: lbs in a 200 lb player)
2, 4lbs
how most research show that sport drinks out perform water for athlete rehydration.
- encourages voluntary drinking when
❑ athletes hot and thirsty (flavour)
❑- stimulates rapid fluid absorption
❑ (mix of carbs <7%, electrolytes)
❑- helps prevent dehydration
dehydration factor
- When athletes do not replenishlost fluids… leads to dehydration
❑Mild dehydration is often unavoidable (< 2% body weight loss BWL )
❑Difficult to maintain peak hydration, as little as 2% BML can begin to hinder performance thermo- regulatory function
❑Optimum hydration is the replacement of fluids and electrolytes in accordance with individual needs.
❑Fluid intake = Fluid losses
❑Fluid intake beyond fluid needs for many hours can also be quite harmful.
recognition of dehydration
❑Thirst
❑Dry mouth
❑Headache
❑Head/Neck heat sensation ❑Apathy
❑Chills
❑Excessive fatigue ❑Irritability
❑Weakness
❑Vomiting
❑Decrease performance ❑General malaise ❑Dizziness
❑Cramps
Maintaining normal hydration (as per baseline body weight) is critical If athlete’s BWL is > % within a given day, should _
Maintaining normal hydration (as per baseline body weight) is critical If athlete’s BWL is > 1-2% within a given day, should return to normal hydration status before being allowed to practice.
Fluid deficits should be replaced within _hrs after exercise
is complete
1-2
_ with + _ optimal before & during exercise (athletes usually only replace 1⁄2 of fluid lost when drinking plain water)
sport drink, carbs + electrolyte
T/F.A nauseated / vomiting athlete should seek medical attention (IV fluid)
T
T/F. If dehydration minor and athlete symptom free ….may return
T
Do not allow hydration losses to go above % body weight
2
When high rate of fluid intake necessary:
When high rate of fluid intake necessary: carb composition <7%
Factors that may increase the risk associated with exercise in the heat include:
INTRINSIC:
History of exertional heat illness ❑Inadequate heat acclimatization ❑ Lower level of fitness
❑High % body fat
❑Dehydration or over-hydration ❑Presence of a fever
❑Presence GI illness
❑Salt deficiency
❑Skin condition (sunburn, skin rash etc)
❑ Medications(anti-histamines,diuretics,ephedra) ❑Motivation to push oneself (warrior) ❑Reluctance to report problems: macho/macha ❑ Pre-pubescence
Factors that may increase the risk associated with exercise in the heat include:
EXTRINSIC:
Intense/prolonged exercise with minimal breaks ❑ High temperature/humidity/sun exposure
❑ Previous days exposure to heat / humidity
❑ Inappropriate work/rest ratios based on intensity, ❑ WBGT
❑ Clothing
❑ Equipment
❑ Fitness
❑ Medical conditions.
❑ Lack of education/awareness heat illness among coaches, athletes, medical staff
❑ No EAP to identify/ tx exertional heat stress
❑ No access to shade during exercise or rest breaks
❑ Duration and number of rest breaks is limited
❑ Minimal access to fluids before /after practice and rest breaks is limited
❑ Delay in recognition of early warning signs
Exertional heat stroke is a severe illness characterized by
Exertional heat stroke is a severe illness characterized by CNS abnormalities and potentially tissue damage.
Exertional heat stroke result from
elevated body temperatures induced by strenuous physical exercise and increased environmental heat stress.
critical factors of Exertional heat stroke
- CNS dysfunction-
❑ altered consciousness
❑ coma
❑ convulsions,
❑ disorientation,
❑ irritable behaviour, ❑ ↓ mental acuity
❑ emotional instability, ❑ confusion,
❑ hysteria
❑ apathy
BP, HR and RESP of Exertional heat stroke
increase HR, decrease BP, increase rest
