CBC count, renal function, and liver function were all normal. Her electrolytes were notable for the following: sodium, 133 mEq/L; potassium, 2.6 mEq/L; chloride, 101 mEq/L; and bicarbonate, 22 mEq/L. An arterial blood gas analysis obtained on 100% oxygen via a nonrebreather mask revealed pH 7.38, Pco2 of 38 mm Hg, Po2 of 52 mm Hg, and HCO3 of 24 mEq/L. Cardiac enzymes were normal. D-dimer was 3.7 μg/mL (normal < 0.5 μg/mL), and lactic acid was 1.4 mEq/L.