Question

why would you not give a patient suffering from a long-term lung diease like emphysema a lot of oxygen at once?

Answer 1

The patient suffering from Long term lung disease which is chronic obstructive pulmonary disease would not give too much of oxygen at once because it creates a oxygen toxicity that is oxygen induced hypercarpnia. This leads to increase the saturation of oxygen and retains the carbon dioxide that leads to respiratory acidosis and even death.

By two mechanism ventilatory perfusion mechanism and by Haldane effect the oxygen induced hypercarpnia occurs in supplemental oxygen. In excess supplemental oxygen, the ventilation perfusion matching mechanism there is no localized vasoconstriction which leads to abnormal redistribution of blood to the lung areas that mismatch the ventilation perfusion leads to poor ventilation andmakes the carbondioxide difficult to eliminate from the body. This leads to oxygen induced hypercarpnia.

In haldane effect, the excess supplemental oxygen leads to decrease the deoxygeneated hemoglobin which directly reduces the carbondioxide amount that carries via blood that leads to oxygen induced hypercarpnia.