A 63-year-old man with an extensive history of cigarette smoking and severe chronic obstructive pulmonary disease (COPD) (first expiratory volume in 1 second [FEV¹] <25% predicted and resting PaO₂ <55 mm Hg) presents to a pulmonary specialist for management. He states that he has been free of cigarettes for almost 1 year but his poor oxygenation severely limits his functional ability. He is thus deemed a suitable candidate for lung transplantation. After a relatively short period on the transplant list, the patient receives a left single lung from an otherwise healthy 24-year-old donor who died from head injuries in a motorcycle crash.

The operation progresses smoothly and the patient is transferred to the cardiac surgical intensive care unit (CSICU) postoperatively. Initial arterial blood gas measurement shows the arterial partial pressure of oxygen to be only 55 mm Hg on a fraction of inspired oxygen (FIO₂) of 100%. The resident physician orders an increase in the positive end-expiratory pressure (PEEP) on the ventilator from 5 to 10. Subsequent blood gas shows a worsening of oxygenation with a PaO2 of 45 and PaCO₂ of 55. In an effort to improve the patient’s respiratory status, he is disconnected from the ventilator and hand bagged. His oxygenation continues to decline and now his blood pressure drops precipitously. He becomes bradycardic and ultimately arrests.