A 54-year-old man sustains third degree burns in a house fire. His respiratory rate is 30/min, Hb = 17 g/dL, arterial PO2 is 95 mm Hg, and arterial O2 saturation is 50%. The most likely cause of his low oxygen saturation is:
Airway obstruction from smoke inhalation
Carbon monoxide poisoning
Pulmonary edema
Fever
Ans. B. Carbon monoxide poisoningCarbon monoxide will lower oxygen content and saturation, but the arterial PO2 is unchanged. Airway obstruction or pulmonary edema will lower O2 saturation and arterial PO2 .
Respiratory System