HOT / COLD/ ALTITUDE Flashcards
Exercise related causes of unwell athlete
Exertional Heat stroke
Exercise related Hyponatremia
Hypothermia
General Management of Unwell athlete
A - Airway B - Breathing C - Circulation and temperature D - Disability (AVPU, PEARL, CGG) E - Environment F - Fluid status G - Glucose and sodium H - History, incl site of collapse
Exertional Heat Exhaustion
Inability to continue exercise
Can happen in all temperatures but more common in hot; dehydration, esp after running
Patho
- Heat and dehydration => tachycardia, central fatigue and peripheral vasodilation
- Peripheral vasodilation => hypotension, CV insufficiency + blood pooling
- Blood pooling further worsens hypotension and reduces heat transfer to periphery
S&S
Sweaty, pale/ashen. Headache. Dizziness. N&V. Muscle fatigue. - reduced coordination and cramps, weakness
ABCDEFGH B - Tachypnoea C - Tachycardia, Postural hypotension E - <40 degrees F - normal or dry H - likely collapse after cessation of exercise
How do you differentiate between EHE and EHS?
Core body temp
Mental function
Exertional Heat Stroke
Predisposing Factors
Strenuous exercise, hot-humid environment, poor acclimatization, poor physical fitness
Patho
Core temperature reaches >40 causing cellular membrane damage and disrupting the cellular energy systems. This causes cell and organ dysfunction and subsequently failure. Multiple system involved - brain, liver, kidneys, heart, muscle. GI
Tachycardia. May or may not be sweating. Altered mental state (confusion/disorientation → seizures → coma). Irrational behavior. Vomiting. Diarrhoea. Post episode do not recall last 35-45min.
ABCDEFGH B - Tachypnoea C - Hypotensive, tachycardic D - Altered mental state E - Rectal temp >40 F - Exercise induced hyponatremia => fluid retention, puffy H - During event, can also occur after
EHS Treatment
MEDICAL EMERGENCY - ACTIVE COOLING ASAP
- Remove excessive clothing
- Ice baths and fans
- Ice packs: 2 at neck, 2 under armpits, 2 on groin
- PO fluids
Exercise Associated Muscle Cramps
Painful spasms of skeletal muscle
common after long, high intensity sports
Risk factors
Dehydration, large sweat Na loss, exercise induced muscle fatigue
Rx
Rest, stretching, oral Na-containing foods and fluids
Prevention of heat related problems
Good schedule of events, activity modification and appropriate clothing
Heat acclimatisation e.g. heat baths
Hydration and nutrition
Normothermia
35-39
Mild hypothermia
& physiological response
33-35
Maximal shivering
Dysarthria, amnesia, poor judgment
Moderate hypothermia
& physiological response
29-32
Shivering ceases
Stupor, arrhythmias, unconsciousness
Severe hypothermia
& physiological response
<29
VF
Loss of reflexes and voluntary motion, acid-base distur
Physiological responses to cold
- Peripheral vasoconstriction
2. Skeletal muscle contraction (voluntary modified behaviour)
Mechanisms of hypothermia
decreased heat production
increased heat loss
impaired thermoregulation
Aetiology of decreased heat production
Training
Inactivity, fatigue, energy depletion
Endocrine
Hypothyroidism, hypopituitarism, hypoglycaemia
Aetiology of increased heat loss
Training
Immersion, rain, wet clothing, wind, low body fat
Erythroderma
Burns, psoriasis, sunburn
Aetiology of impaired thermoregulation
Peripheral failure
Spinal cord transection
Trauma
Neuropathies
Central failure CNS lesion Cerebrovascular Accident Subarachnoidhaemorrhage PD Hypothalamic dysfunction Drug and alcohol abuse
Trenchfoot
Non-freezing injury - 0-15 degrees; prolonged exposure (12hr-4d)
Swollen, erythematous Red -> pale -> cyanotic numbness diminished peripheral pulses pain and increased sensitivity
Chillbains
Non-freezing injury - 0-15 degrees; short exposure (1-5hr
Superficial cold injury
Red, itchy, swollen papules on dorsum of fingers, ears and face
Painful, swollen, tender
Upon rewarming remain hot to touch, inflamed with burning and pain sensation lasting
Frostbite
<0 degrees
wet skin more likely
common in exposed skin sites (nose, ears, hands, feet)
pain
numbness
wooden sensation
upon re-warming significant pain
Cardiac Arrhythmias
Potentially fatal
ECG
Sinus bradycardia, J wave (repolarisation abnorm after QRS), prolonged PR interval
Composition of the atmosphere
Troposphere
Stratosphere
Mesosphere
Partial Pressure of O2
P of a gas is proportional to the concentration of the gas and barometric pressure
PO2 = PB x FiO2
Sea level PO2 = 101.3 kPA x 0.2095 = 21.1 kPA
Top of mount everest PO2 = 7.6 kPA
As you elevate abose sea level the atmospheric pressure decreases exponentially
Acute Mountain Sickness
Recent gain in altitude >2500m Secondary to hypoxia Headache + at least one of: - nausea, anorexia, vomiting - dizziness - fatigue or weakness - difficulty sleeping
No physical signs
onset within 6-12 hrs
Rx
- stop and rest; do not ascend until sx resolve (1-2d)
- analgesia +/- anti-emetics
- if sx worsen
- descend!!
- acetazolamide 250mg BD
- dexamethasone 4mg QDS
- O2
High Altitude Cerebral Edema
Vasogenic oedema due to hypoxia - leaky cerebral vessels
Disorientation, lethargy, nausea, confusion, LOC, ataxia, severe headaches
Rx
Descend
High flow oxygen
acetazolamide and dexamethasone
Not treatment = coma and death
High Altitude Pulmonary Edema
Non cardiogenic pulmonary oedema secondary to hypoxia
Defined by the Lake Louise Consensus
- At least two symptoms of
- dyspnoea
- cough
- weakness or decreased exercises performance
- chest tightness or congestion
- At least 2 signs of
- Tachypnoea
- Tachycardia
- Wheezing or crackles in at least one lung field
- Central cyanosis
Rx
- descend and O2
- Dexamethasone
- Nifedipine (given at lower altitudes)
At what heigh should altitude training occur?
> 1500-2500m above sea level
Why do altitude training?
VO2 max is reduced at 700m
Reduced PO2 causes physiological adaptations over days to weeks; consider individual varioations
What is desirable effect and the physiological adaptations?
Sustained hypoxia causes increased EPO production and thus oxygen capacity of blood
- Carotid bodies: sensitive to PaO2, PaCO2 and pH
- Increase ventilation
- Increase HR and CO
- Hypoxia causes EPO production
- Increased RBC production
Methods of altitude training
Natural altitude: to see effect needs to stay in chamber for at least 16h/d - hypobaric hypoxia - normobaric hypoxia - normobaric hyperoxia Live high, train high Live high, train low Live low, train high
