Which of the following statement(s) is/are true concerning respiratory acidosis?

b. The initial buffering effect occurs at the cellular level

d. Correction of hypoxemia in patients with chronic lung disease may worsen respiratory acidosis

Respiratory acidosis, the decrease in extracellular pH from a primary increase in PCO2, is due to inadequate ventilation. Although pulmonary disease commonly causes hypoxemia, respiratory acidosis is far less common, since defusion of O2 is more readily impaired than diffusion of CO2. Increased PCO2 results in increased H2CO3 which disassociates into H+ and HCO3–. Cellular exchange of Na+ and K+ for H+ allows the reaction to continue in this direction with increased extracellular bicarbonate. This tissue buffering is accomplished within minutes. Persistently elevated PCO2 also stimulates increased renal acid excretion. Full renal compensation occurs over 3 to 5 days. The treatment of chronic compensated respiratory acidosis may be complicated by accompanying hypoxemia. In chronic hypercapnia, the chemical chemoreceptors may be insensitive and the accompanying hypoxemia may supply the main respiratory drive through the stimulation of peripheral chemoreceptors. In such patients, complete correction of hypoxemia may further depress respiration and worsen the respiratory acidosis.