Ch. 9 West Flashcards
High altitude (increases/decreases) the partial pressure of inspired oxygen
Decreases
What is the most important feature of acclimatization to high altitude?
Hyperventilation
What is the mechanism for hyperventilation in high altitude?
Peripheral chemoreceptor stimulation by hypoxemia
What other feature develops secondary to being present at high altitude?
Polycythemia - tends to maintain the PO2 of mixed venous blood
Why does polycythemia develop?
Initially the hemoglobin concentration is caused by hemoglobin concentration due to reduction in plasma volume.
Subsequent increases occur due to EPO stimulation within 2-3 days of exposure to high altitude
Which direction does the oxygen dissociation curve shift with moderate altitude?
Right (helps offload oxygen) - develops because of increased 2,3-DPG in the blood which results from the alkalosis that develops
T/F: At higher altitudes, there is a leftward shift of the curve due to continued alkalosis
True
How does PH develop secondary to high altitude?
Alveolar hypoxia - pulmonary vasoconstriction
Increases the pulmonary arterial pressure and work done by the right heart
Hypertension exacerbated by polycythemia
Prolonged changes include right heart hypertrophy
The hypoxic pulmonary vasoconstriction is NOT advantageous in this situation
What is absorption atelectasis?
A danger of breathing FiO2 100%
If a region is atelectatic, and the patient has been breathing 100% FiO2, the partial pressure in the closed off alveolus will be way higher than the blood perfusing it, and gas will rapidly diffuse into the blood leading to rapid alveolar collapse.
With hyperbaric oxygen therapy, how many atm is the chamber raised to and how much does this raise the dissolved arterial oxygen?
3 atm
Raises it to 6 mL dissolved O2 per 100 mL blood
