A elderly gravida (G6P5) became disoriented, lightheaded, breathless, and cyanotic 20 minutes after an uncomplicated spontaneous vaginal term delivery. Her blood pressure is 80/40 mm Hg, pulse is 110/min, and respiratory rate is 30/min. O2 saturation is 75% on face mask.A generalized purpuric rash and bleeding from the I.V line site are seen. Which of the following is the most appropriate next step in management of this patient?
Abdominal ultrasound Intramuscular magnesium sulfate Intravenous heparin Intubation and mechanical ventilation