Chest
Volume 127, Issue 3, March 2005, Pages 892-901
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Clinical Investigations: Surgery
Pulmonary Outcomes of Off-Pump vs On-Pump Coronary Artery Bypass Surgery in a Randomized Trial

https://doi.org/10.1378/chest.127.3.892Get rights and content

Study objectives

Comparison of pulmonary outcomes after off-pump coronary artery bypass (OPCAB) vs on-pump coronary artery grafting with cardiopulmonary bypass (CABG/CPB)

Study design

We examined preoperative and postoperative respiratory compliance, fluid balance, hemodynamics, arterial blood gases, chest radiographs, spirometry, pulmonary complications, and time to extubation in a prospective trial of 200 patients randomized to OPCAB vs CABG/CPB performed by one surgeon

Results

One CABG/CPB patient and two OPCAB patients required mitral valve repair or replacement and were withdrawn. After three crossovers from CABG/CBP to OPCAB and one crossover from OPCAB to CABG, 97 CABG/CPB patients and 100 OPCAB patients remained. There were no significant preoperative demographic differences between groups. Postoperative compliance was reduced more after OPCAB than after CABG/CPB (− 15.4 ± 10.7 mL/cm H2O vs − 11.2 ± 10.1 mL/cm H2O [mean ± SD]; p = 0.007), associated with rotation of the heart into the right chest to perform posterolateral bypasses (p < 0.001) and the concomitant increased fluid requirements necessary to maintain hemodynamic stability during rotation of the heart. In addition to higher intraoperative fluid intake (4,541 ± 1,311 mL vs 3,585 ± 1,033 mL, p < 0.0001), OPCAB patients had higher intraoperative fluid balance (3,903 ± 1,315 mL vs 1,772 ± 1,373 mL, p < 0.0001), and higher postoperative pulmonary arterial diastolic pressure (15.0 ± 5.5 mm Hg vs 11.8 ± 5.2 mm Hg, p < 0.0001) and central venous pressure (10.4 ± 4.5 mm Hg vs 8.4 ± 4.7 mm Hg, p < 0.0001). Despite lower compliance, immediate postoperative Pao2 on fraction of inspired oxygen of 1.0 (275 ± 97 torr vs 221 ± 92 torr, p = 0.001) was higher after OPCAB and extubation was earlier (p = 0.001). Postoperative chest radiographs, spirometry, mortality, reintubation, or readmission for pulmonary complications were not different between groups

Conclusions

Compared to CABG/CPB, OPCAB was associated with a greater reduction in postoperative respiratory compliance associated with increased fluid administration and rotation of the heart into the right chest to perform posterolateral grafts. OPCAB yielded better gas exchange and earlier extubation but no difference in chest radiographs, spirometry, or rates of death, pneumonia, pleural effusion, or pulmonary edema

Section snippets

Patient Selection, Randomization, Care, and Data Collection

The SMART trial3233 was designed to compare completeness of revascularization, graft patency, clinical outcomes, and resource utilization in unselected patients referred for elective, primary coronary bypass surgery randomized to undergo OPCAB with a stabilization device (Octopus; Medtronic; Minneapolis, MN) or CABG/CPB at a single hospital by a single surgeon. Patients were not excluded on the basis of any preoperative comorbidities or any pattern of coronary artery disease.32, 33

Patients were

Patients

Two hundred patients agreed to participate. Three patients were determined by transesophageal echocardiography after randomization and induction of anesthesia to require mitral valve repair or replacement and were withdrawn from the study. The study groups were 99 patients who were to undergo CABG/CPB and 98 patients who were to undergo OPCAB. Three patients had severe aortic calcification or atherosclerosis by epiaortic ultrasound and/or transesophageal echocardiography after randomization in

Discussion

This is the largest prospective randomized trial to date to provide comprehensive analysis of the pulmonary aspects of OPCAB vs CABG/CPB. We have demonstrated that a greater decrease in postoperative respiratory static compliance seen in the OPCAB patients appears to be due to the need to rotate the heart into the right chest to allow bypass to posterolateral vessels and the larger amounts of IVF required to maintain systemic BP during the operation. Paradoxically, CABG/CPB patients actually

Acknowledgments

We are indebted to Roland H. Ingram, MD, for his helpful discussions of the respiratory static compliance data and review of the manuscript, and we also thank Kenneth V. Leeper, MD, and Bruce Krieger, MD, for their helpful comments. We could not have performed this study without the help of our nurse coordinators, Susan A. McCall, RN, Bonnie Sammons, RN, and Rebecca J. Peterson, RN.

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    Dr. Duke has received consultant fees from Medtronic, Inc., and Dr. Puskas has received consultant fees and speaker honoraria from Medtronic, Inc

    This study was supported by grants from Medtronic, Inc, Minneapolis, MN; and The Carlyle Fraser Heart Center Foundation, Atlanta, GA

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