Because of the patient’s illness, fetal distress, and oligohydramnios, labor was induced and a healthy baby boy was delivered. Over the next 24 h, the patient’s respiratory status deteriorated with increased work of breathing, worsening tachypnea, and hypoxia. Arterial blood gas analysis on 100% nonrebreather mask showed a pH of 7.29; Pco2, 41 mm Hg; and Po2, 46 mm Hg. The lactic acid was 3.4 mmol/L (normal range, 0.4 to 2.0). Subsequently, the patient was transferred to ICU, intubated, and administered mechanical ventilation, with the subsequent arterial blood gas analysis showing a pH 7.33; Pco2, 36 mm Hg; and Po2, 237 mm Hg on 100% oxygen.