Peripheral pulmonary atelectasis and oxygentation impairment following coronary artery bypass grafting

Severe pulmonary oxygenation impairment occurred in some patients with pleurotomy during the harvest of the internal mammary artery graft followed by coronary artery bypass grafting (CABG). Peripheral pulmonary atelectasis in the postoperative chest X-ray was detected in these patients. We studied the efficacy of intraoperative positive end-expiratory airway pressure (PEEP) therapy for the prevention of postoperative pulmonary oxygenation impairment.

The pleural cavity was intraoperatively opened in 40 patients with solitary CABG procedure performed during 5 years since January 1992. These patients were divided into two groups. Intraoperative PEEP therapy, which is initiated just after pleurotomy, was not used in 32 patients before May, 1996 (control group) and used for recent 8 patients with pleurotomy (PEEP group). The mean age of patients was 60 years old in the control group and 68 in the PEEP group.

Respiratory insufficiency (A-aDO2 >400 mmHg and RI >1.5) was detected in 6 patients in the control group. Three out of these 6 patients required long-term mechanical respiratory support over a week. No respiratory insufficiency occurred in patients of the PEEP group. Values of PaO2, A-aDO2, respiratory index and shunt ratio were significantly worse in the control group than in the PEEP group.

In conclusion, PEEP therapy may prevent pulmonary atelectasis and oxygen impairment after CABG.