When does a state of alkalemia exist? 1. The HCO3–/CO2 ratio exceeds 20:1. 2. The blood pH exceeds 7.45. 3. The blood PCO2 exceeds 54 mm Hg

a. 2 and 3 only
b. 1, 2, and 3
c. 3 only
d. 1 and 2 only

ANS: D
An increase in [HCO3–] or a decrease in PCO2 will raise the pH, leading to alkalemia. This pro-duces a [HCO3–]/(PCO2 ⋅ 0.03) ratio greater than 20:1 (e.g., 25:1). A decreased [HCO3–] or an increased PCO2 decreases the pH, leading to acidemia. This produces a [HCO3–]/(PCO2 ⋅ 0.03) ratio less than 20:1 (e.g., 15:1). The normal ranges for arterial pH, PCO2, and [HCO3–] are as fol-lows:
pH = 7.35 to 7.45
PaCO2 = 35 to 45 mm Hg
[HCO3–] = 22 to 26 mEq/L
Alkalemia is defined as a blood pH greater than 7.45.