Exercise Induced Arterial Hypoxemia (EIAH)

Question 1

What is EIAH?

Answer 1

Exercise Induced Arterial Hypoxemia
- Threat to systemic O2 Transport

Question 2

What are the three levels of EIAH?

Answer 2

• Mild: SaO2 93-95%
• Moderate: SaO2 88-93%
• Severe: SaO2 < 88%

Question 3

What does a 3% decrease in SaO2 require? What does this signify?

Answer 3

10mmHg decrease in PaO2
- Failure of lung to maintain arterial oxygenation

Question 4

Why would there be abnormal gas exchange during EIAH?

Answer 4

• Widening of A-aDO2(first alveolar-arterial oxygen gradient)
• Insufficient Alveolar Hyperventilation

Question 5

What is a normal A-aDO2? and PaCO2?

Answer 5

• 15-25mmHg
• PaCO2 30-35mmHg

Question 6

What would an A-aDO2 of >35-40mmHg represent?

Answer 6

• a Severe inefficiency in gas exchange

Question 7

What would a PaCO2 of >38mmHg represent?

Answer 7

• Absence of compensatory hyperventilatory response

Question 8

In the study on EIAH, who was affected?

Answer 8

Highly Trained Participants
- 52% of

Question 9

What was unique about women who had EIAH? What about men?

Answer 9

Women
- Half who had EIAH, had VO2max within 15% predicted normal levels
Men
- Only seen in those with High Aerobic Capacity (150-200% normal VO2max)

Question 10

What is the relationship between habitually active subjects and EIAH?

Answer 10

• EIAH only seen in high trained individuals
• Correlation between EIAH to VO2max usually significant

Question 11

Is the Lung Built for exercise? why or why not?

Answer 11

No
- High VO2max increases demand of lung and respiratory muscle
- little to no change in capacity

Question 12

What are the causes of EIAH?

Answer 12

• Absence of hyperventilation (mechanical constraint)
• Widening of A-aDO2
• VA/Q inequality
• Diffusion limitation
• Right-to-left Shunt

Question 13

Who had the Higher VO2max average and max during middle & long-distance running? Kenyan or Scandinavian Runners?

Answer 13

• Kenyan

Question 14

What were the Key findings on the study of Kenyan Runners?

Answer 14

• Significant gas exchange impairments during exercise
• Expiratory flow limitation
• Have high work of breathing

Question 15

What do the key findings of the study of kenyan runners imply?

Answer 15

Pulmonary system limitations present in runners of Kenyan Ancestry
- dominance in running events unlikely due to enhanced pulmonary system or ventilatory response to exercise