Based on the following ABG results, what is the most likely acid-base diagnosis? pH = 7.62, PCO2 = 32 mm Hg, HCO3– = 29 mEq/L

a. Acute (uncompensated) metabolic alkalo-sis
b. Combined metabolic and respiratory alka-losis
c. Partially compensated metabolic alkalosis
d. Partially compensated respiratory acidosis

ANS: B
A combined disturbance is one in which both respiratory and metabolic disturbances exist, which promote the same acid-base disturbance. For example, consider the following arterial blood gas results: a pH value of 7.62, a PaCO2 value of 32 mm Hg, and an HCO3– value of 29 mEq/L. The pH indicates alkalemia, consistent with both the low PaCO2 and the elevated HCO3–. This is a combined alkalosis, indicating that the patient has two primary acid-base problems (i.e., respira-tory and metabolic alkalosis combined). Therefore, compensation is not possible.