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Question 5#

A 70-year-old patient with chronic obstructive lung disease requires 2 L/minute of nasal O 2 to treat his hypoxia, which is sometimes associated with angina. The patient develops pleuritic chest pain, fever, and purulent sputum. While using his oxygen at an increased flow of 5 L/minute, he becomes stuporous and develops a respiratory acidosis with CO2 retention and worsening hypoxia. What would be the most appropriate next step in the management of this patient?

A) Stop oxygen
B) Begin medroxyprogesterone
C) Intubate and begin mechanical ventilation
D) Treat with antibiotics and observe on the general medicine ward for 24 hours
E) Begin sodium bicarbonate

Correct Answer is C

Comment:

This patient presents with severe COPD and hypoxemia. Chronic CO2 retention has blunted his hypercarbic drive to breathe; he is dependent on mild hypoxia to stimulate respiration. An inappropriately high oxygen delivery has decreased even that drive, with resulting acute respiratory acidosis and CO2 narcosis. However, stopping the oxygen will result in severe hypoxemia. Of the choices listed, the initiation of mechanical ventilation is the only acceptable choice. If the patient’s mental status were better, noninvasive ventilation (BiPAP) might be considered. Medroxyprogesterone has only a mild stimulatory effect on the respiratory center, and is not appropriate therapy in this case. Antibiotics and inhaled bronchodilators are appropriate treatments for COPD exacerbation but would not manage this patient’s acute hyper-carbic respiratory failure. The patient has declared a deteriorating course. Continuing to monitor his status on the general medicine ward would probably be fatal. This patient has respiratory (not metabolic) acidosis. Bicarbonate plays a minimal role in this acidosis. The correct therapy is to improve the patient’s ventilation.