Question
A 65-year-old patient presents with chronic obstructive pulmonary disease. The exam shows a barrel chest and the patient is pursing their lips. The lung exam shows distant breath sounds and they are hyper resonant. They are hypoxic and develop hypercapnia over time. Which of the following are the compensatory measures in these patients?
| A. |
The shift of normal respiratory drive to hypercapnic drive
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| B. |
Renal compensation to maintain near-normal pH
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| C. |
Maintenance of the ventilation-perfusion (V/Q) ratio by compensatory renal vasodilation
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| D. |
Maintenance of pH by pulmonary vasoconstriction
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Show Answer
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Correct Answer � B
Explanation
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Ans. B
Pulmonary vasoconstriction to preserve the V/Q ratio, renal compensation to maintain near-normal pH, and hypoxic drive are the important compensatory measures in patients with chronic obstructive pulmonary disease (COPD).
The target oxygen pulse oximetry in patients with COPD is important. It is 88% to 92%. Increasing oxygen saturation beyond 92% negatively affects the compensatory measures.
The kidneys compensate by retaining more bicarbonate and, hence, neutralizes the acidity due to hypercapnia in these patients.
The chemoreceptors become tolerant to chronically elevated carbon dioxide in patients with COPD. Therefore, low oxygen plays a major role in the stimulation of chemoreceptors and maintains the respiratory drive.
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