3 Short term responses to cold water immersion

Question 1

Stages of cold water immersion

Answer 1

Initial responses - first 3 min
Peripheral cooling < 30 min
Hypothermia
Post immersion collapse

Question 2

Drowning- Lethal volume of aspirated water:

Answer 2

Sea water = 22 ml.kg-1 ~ 1.5 L in an adult, fluid pours into
lungs from blood due to osmosis – wet lung
 Fresh water = 44 ml.kg-1 ~ 3 L in an adult, rapidly absorbed - dry lung

Question 3

Drowning Mechanisms

Answer 3

Disruption of the surfactant – collapsed lung
 Inflammatory response – pulmonary oedema
reducing surface area for gas exchange (death from
near-drowning)
 Fluid in lungs increases pulmonary artery pressure –
venous congestion – less blood returning to left atria
– cardiac output and blood pressure fall
 Death through asphyxia & cardiac failure

Question 4

Cause of drownings

Answer 4

• Sudden death on immersion in cold water- ectopics

- Cold shock

Question 5

Cold Shock Mechanisms

Answer 5

NOT a thermoregulatory response
 Stimulation of cold receptors
 Lasts approx 3 min
 Increased sympathetic output
 Vasoconstriction, tachycardia, increased heart
contractility
 Increased rate &; depth of breathing
 Catecholamine release from adrenal medulla

Question 6

Water Temperature

Answer 6

 Inverse relationship between response and
water temperature down to approx 15°C
 Responses in 0°C same as 5-15°C
 Maximum response same in 5°C and 10°C but in 5°C duration longer
 Rate of change in deep Tsk determines magnitude of response

Question 7

Factors affecting response

Answer 7

Fitness
Breath hold time in air
Gender
Alcohol

Question 8

Swim Failure 1

Answer 8

Clothed swim in 2°C - poor & moderate swimmers stopped after 2 min

Clothed swim in 6°C & 25°C - all swam for 10 min in warm but only 3/10 managed in cold.

Question 9

Swim Failure 2

Answer 9

swimming efficiency decreases
 SE <5 m L-1 VO2 - swim failure
- Deterioration in swimming technique
 near-drowning rather than severe hypothermia