Is Atelectasis Following Aortocoronary Bypass Related to Temperature?

¹ From the Division of Cardiovascular Surgery, The Toronto Hospital, Toronto, Ontario, Canada
² From the Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada

Objective: To determine the frequency of acute postoperative atelectasis in patients undergoing aortocoronary bypass with either normothermic (warm) or hypothermic (cold) technique.

Design: Prospective, randomized study comparing two groups.

Setting: University-affiliated hospital.

Patients: Three hundred thirty-one patients (166 cold and 165 warm) undergoing isolated aortocoronary bypass.

Measurements: Chest radiographs were obtained preoperatively, on the day of surgery, and subsequently as clinically indicated until discharge from the hospital. Radiologist (blinded to the patient allocation into warm or cold group) scored the atelectasis from 0 to 3 based on its severity. Regression analysis was used to determine if there was any difference in the atelectasis scores between the two groups.

Results: Mean daily postoperative atelectasis scores were not different between the cold and warm groups. The number of patients requiring chest radiographs was similar in both groups. The percent of patients with abnormal chest radiographs was similar in both groups.

Conclusion: The temperature of cardioplegia has no effect on the development of atelectasis following aortocoronary bypass, and therefore temperature-related cold injury is not a major cause of atelectasis following this type of surgery.

Key Words: atelectasis • cold heart surgery • warm heart surgery

Submitted on January 5, 1996
Accepted on November 8, 2007