Chest wall motion and pulmonary function are more diminished following cardiac surgery when the internal mammary artery retractor is used

Abstract

OBJECTIVES: Pulmonary complications following cardiac surgery through sternotomy have been widely studied. The duration of these complications, however, has been less studied and the proposed alterations in chest wall mechanism even less. The purpose of this study was to investigate changes in chest wall motion and pulmonary function of cardiac surgery patients, where both the median and the internal mammary artery retractor was used (IMA group) and cardiac surgery patients, where only the median retractor was used (Median group). DESIGN: Subjects were 20 cardiac surgery patients with mean age 65 years (12 in the IMA group and 8 in the Median group). Bilateral respiratory movements (RMs) using the Respiratory Movement Measuring Instrument, lung volumes including vital capacity (VC), forced vital capacity (FVC) and forced expiratory volume (FEV1) using the Vitalograph Alpha were measured and pulmonary radiographs analyzed before, 3 and 12 months after the operation. ANALYSIS: Descriptive statistics, t-tests, Mann-Whitney and Wilcoxon Signed Rank tests were used for analyses, p < or = 0.05. RESULTS: RMs were symmetrical in both groups prior to the operation and the differences in RMs and lung volumes between the groups were not significant. Three and 12 months postoperatively bilateral abdominal respiratory movements (ARM) were significantly less in the IMA group than in the Median group. Average left ARM were significantly less than the average right ARM in the IMA group 3 months postoperatively, while symmetrical in the Median group. Average FVC and FEV1 were significantly less in the IMA group than in the Median group 3 months postoperatively and FVC was still significantly less in the IMA group 12 months after the operation. CONCLUSION: The significantly more reduced ARM and lung volumes 3 months postoperatively in the IMA group than in the Median group suggests that the IMA retractor causes greater injury to the rib cage and the diaphragm.