33. Altitude Physiology

Question 1

What effect does altitude have on barometric pressure?

Answer 1

Decreases

Question 2

What effect does altitude have on PO2?

Answer 2

Decreases due to a decrease in pressure (air content is still the same)

Question 3

What effect does altitude have on PCO2?

Answer 3

Decreases due to hyperventilation

Question 4

What effect does altitude have on the cardiovascular system?

Answer 4

Pulmonary hypertension due to reaction to global hypoxia
Increased heart rate (increased carotid body stimulation)
Vasodilation

Question 5

What effect does altitude have on blood pH?

Answer 5

Respiratory alkalosis due to lack of H+

Question 6

What effect does altitude have on the CNS?

Answer 6

Drowsiness, decreased manual dexterity, judgement and memory
Euphoria
Coma

Question 7

What are the chronic effects of altitude on the CV system?

Answer 7

CO and HR return to normal
Pulmonary Arterial Pressure still high
Increased tissue vascularity
Increased erythropoietin, hematocrit, haemoglobin, blood volume and 2,3-DPG

Question 8

What chronic effects does altitude have on acid-base balance?

Answer 8

Renal compensation/acclimatisation

More bicarbonate is excreted in urine

Question 9

What are the symptoms of acute mountain sickness?

Answer 9

Dyspnoea, palpitations, fatigue, muscular weakness, drowsiness, sleeplessness, dizziness, headache, nausea, anorexia, decreased visual clarity, pulmonary hypertension, cerebral and pulmonary oedema

Question 10

Treatment of acute mountain sickness

Answer 10

Descent
Acetazolamide (increases excretion of bicarbonate)
Gamow bag

Question 11

What are the symptoms of chronic mountain sickness?

Answer 11

Excessive increase in hematocrit
Severe pulmonary hypertension
Right heart failure