Original Articles
Effect of cardiopulmonary bypass on pulmonary gas exchange: a prospective randomized study

https://doi.org/10.1016/S0003-4975(99)01196-0Get rights and content

Abstract

Background. Conventional coronary artery bypass surgery is associated with postoperative pulmonary dysfunction. Inflammation due to cardiopulmonary bypass has been regarded as one of the main causes. In this study, we investigated the effect of coronary revascularization with or without cardiopulmonary bypass on pulmonary function.

Methods. Fifty-two patients (40 male, mean age 60.1 years) were prospectively randomized to undergo coronary revascularization via median sternotomy, with or without normothermic cardiopulmonary bypass. Alveolar-arterial oxygen gradients were measured before and after induction of anesthesia, postoperatively in the intensive care unit during mechanical ventilation and 6 hours after tracheal extubation. The techniques of anesthesia and mechanical ventilation were standardized throughout.

Results. Patient characteristics were similar in the two groups. The alveolar-arterial oxygen gradients increased progressively throughout the perioperative period, with no significant differences in the two groups at any time during the study.

Conclusions. Myocardial revascularization with or without cardiopulmonary bypass caused a similar degree of pulmonary dysfunction, as assessed by alveolar-arterial oxygen gradient. Our study suggests that the deterioration in pulmonary gas exchange associated with cardiac surgery is due to factors other than the use of cardiopulmonary bypass.

Section snippets

Patient selection

Fifty-two patients undergoing elective CABG were enrolled in the study. Patients were prospectively randomized into two groups: a “CPB Group,” who underwent conventional myocardial revascularization with normothermic CPB and cardioplegic arrest of the heart with intermittent antegrade warm blood cardioplegia; and a “non-CPB Group,” who underwent revascularization on the beating heart. Exclusion criteria were as follows: known pulmonary disease, smoking within previous 6 months, poor left

Results

There were no significant differences in the patient characteristics or operative details between the two groups Table 1, Table 2. Chest tube drainage and volume of fluid administered during the first 24 hours postoperatively were significantly less in the non-CPB group (Table 3).

There was no significant difference between the two groups in the baseline A-a gradient measured before induction of anesthesia (CPB group 19.5 ± 6.2 mm Hg; non-CPB group 16.9 ± 5.1 mm Hg, mean ± SD). Similarly, there

Comment

The desire to minimize complications associated with CPB, as well as the current trend towards cost containment [7], has led to renewed interest in CABG without the use of CPB 4, 8. Brasil and colleagues [3] have shown that the inflammatory response associated with cardiac surgery using CPB is virtually undetectable in surgery performed without CPB. Despite this, only few studies have looked at the effects on end-organ function in association with procedures without CPB. Most studies have

Acknowledgements

We thank Andrew M. S. Black, FRCA, for his advice and practical assistance with the statistical analysis.

This study was supported by the British Heart Foundation and the Sir Sigmund Warburg Voluntary Settlement Fund.

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