A 13-year-old patient with sickle-cell anemia presents with respiratory distress; she has an infiltrate on chest radiograph. The laboratory workup of the patient reveals the following: hemoglobin 5 g/dL; hematocrit 16%; white blood cell count 30,000/mL; and arterial blood (room air) pH 7.1, PO2 35 mm Hg, and PaCO2 28 mm Hg. These values indicate which of the following?