Original articles
Off-pump versus on-pump coronary artery bypass surgery and postoperative pulmonary dysfunction

https://doi.org/10.1053/j.jvca.2004.08.004Get rights and content

Abstract

Objective: To investigate how off-pump coronary artery bypass grafting (CABG) affects postoperative pulmonary function when compared with on-pump CABG.

Design: Prospective clinical study.

Setting: University-affiliated teaching hospital.

Participants: Adult patients (n = 39) undergoing elective coronary artery bypass surgery with or without cardiopulmonary bypass.

Interventions: Two groups of patients were compared: 19 consecutive patients undergoing off-pump CABG surgery and 20 consecutive patients undergoing conventional CABG surgery.

Measurements and Main Results: Pulmonary function tests (flow volume loops and lung volumes with plethysmography) were done preoperatively and 72 hours postoperatively. Arterial blood gases and PaO2/FIO2 were measured at various stages. Sequential chest x-rays were obtained and evaluated for pleural changes, pulmonary edema, and atelectasis. In both groups, PaO2/FIO2 ratios decreased progressively throughout the perioperative period, with no significant differences between the groups at any stage during the study. There was a significant decline in postoperative pulmonary function tests in both groups, but there was no difference between groups at 72 hours postoperatively. No differences were found in the time to extubation, atelectasis scores, or postoperative complications.

Conclusions: Off-pump CABG does not confer major protection from postoperative pulmonary dysfunction compared with CABG surgery with CPB. Strategies for minimizing pulmonary impairment after CABG surgery should be directed to factors other than the use of CPB.

Section snippets

Methods

After approval by the local ethics committee and obtaining written informed consent from each individual, 40 consecutive patients with >2 vessel coronary artery disease were enrolled in the study. Exclusion criteria were emergency surgery, associated significant valvular heart disease requiring surgical repair, previous CABG, poor left ventricular function (ejection fraction <35%), poor preoperative pulmonary function (forced expiratory volume in 1 second [FEV1]/forced vital capacity [FVC] <70%

Results

In all 40 patients, the internal mammary artery was used. One patient in the off-pump group presented persistent hemodynamic instability during the vessel grafting and required urgent conversion to CPB; this patient was analyzed as belonging to the on-pump group. One patient in the on-pump group required ventricular aneurysmectomy and new intra-aortic balloon pump support; this patient died 3 days after surgery in the ICU without extubation and he was excluded from the analysis. Therefore, 20

Discussion

The desire to reduce pulmonary risk and associated morbidity is a major factor that may influence the decision to perform CABG without CPB. However, the findings of the present study do not indicate that avoidance of CPB by using current off-pump techniques significantly reduces the risk for postoperative pulmonary dysfunction after CABG.

Much of the postoperative morbidity after CABG has been attributed to a systemic inflammatory response induced by CPB. CABG procedures performed without CPB

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