4 Hypothermia during cold water immersion and the afterdrop

Question 1

Hypothermia Symptoms least to most severe

Answer 1

• Numbness, impaired functions
• Feeling intense cold and shivering
• Confused, disorientated
• Amnesia, semi conscious
• Unconscious, tendon reflexes absent
• Spontaneous Arrhythmias
• Death

Question 2

Search and Rescue Times in normal clothing

Answer 2

50% survival time:
- 5(c), 1 hr
-10 (c), 2hr
-15 (c), 6hr
S&R= 3-6 times 50%
Wearing buoyancy aid increases survival time in all temps

Question 3

Insulation - intrinsic

Answer 3

• Body fat and unperfused muscle
• Increased %body fat reduces rate of fall of T(re)
  during swims in cold water

Question 4

Exercise in cold water

Answer 4

-Swimming increases heat production by 2.5x but
cooling rate increased by 35% (10°C)
-Increases heat loss from limbs but not trunk - variable
effect on Tcore

Question 5

Clothing and swim performance

Answer 5

-Clothing maintained a higher mean body temperature when swimming in 12°C water
-Clothed swims were slower and shorter compared to naked swims: Naked swims terminated due to
hypothermia, clothed swims terminated due to fatigue

Question 6

Alcohol

Answer 6

• Fall in Tcore-increased rate
• Decrease in shivering
• Increase in comfort

Question 7

After-drop definition:

Answer 7

Continued decline in Tcore following removal from prolonged immersion in cold water (U - shaped graph)

Question 8

Theories on after-drop

Answer 8

Conduction:
-Physical phenomenon until temperature
gradient is reversed
Convection:
-return of cold blood from periphery
-perfusion of cold peripheral tissue on vasodilation