PURPOSE: The present study aims to investigate the influence of Off-Pump Coronary Artery Bypass Grafting (OPCABG) on respiratory function evaluated by spirometry and control of breathing test. The last test to our knowledge is not mentioned in such patients before.
METHODS: We measured FEV1, FVC, FEV1/FVC, FRC, FEF, ERV, IC, Breathing Frequency (BF), Occlusion Resistance (ROcc), RV using He (RV(He)), TLC using He (TLC(He)), RV(He)/TLC(He), Diffusing Capacity (DLCO), P0.1, PIMAX, PEMAX, TI, VT/TI, TI/TTOT, and P0.1/VT/TI in 32 successive patients who had an OPCABG. The measurements were made preoperatively and the fifth postoperative day. Statistical analysis was performed with the aid of the student-t test (p=0.05).
RESULTS: There was no statistically significant change in FEV1/FVC preoperatively vs. postoperatively (81.87±7.396 vs. 81.40±5.843, p=0.601), of BF (19.05±7.277 vs. 21.23±5.554, p=0.011), of ROcc (0.55±0.513 vs. 0.49±0.176, p=0.491), of VT/TI (0.70±0.801 vs. 0.64±0.203, p=0.661) and of TI/TTOT (0.43±0.051 vs. 0.43±0.039, p=0.569). On the contrary, FEV1 (2.80±0.679 vs. 1.66±0.381, p<0.0001), FVC (3.42±0.753 vs. 2.03±0.440, p<0.0001), FRC (3.57±0.819 vs. 2.78±0.669, p<0.0001), FEF (2.86±1.264 vs. 1.50±0.619, p<0.0001), ERV (1.39±0.718 vs. 1.14±0.529, p<0.0001), IC (1.81±0.790 vs. 0.87±0.674, p<0.0001), RV(He) (2.17±0.367 vs. 1.65±0.377, p<0.0001), TLC(He) (5.37±0.878 vs. 3.57±0.668, p<0.0001), RV(He)/TLC(He) (40.94±6.834 vs. 46.21±5.968, p<0.0001), DLCO(7.13±1.794 vs. 4.02±1.135, p<0.0001), P0.1 (0.17±0.129 vs. 0.27±0.128, p<0.001), PIMAX (6.17±2.189 vs. 4.42±1.687, p<0.0001), PEMAX (8.49±3.097 vs. 5.57±2.257, p<0.0001), TI (1.51±0.454 vs. 1.34±0.418, p=0.005) and P0.1/VT/TI (0.31±0.151 vs. 0.43±0.149, p<0.001) changed in a statistically significant way.
CONCLUSION: A restrictive functional abnormality is installed after OPCABG, still present at the 5th postoperative day. It seems that a respiratory muscles impairment may be involved, while the control of breathing results confirm the increased inspiratory activity to affront the disorder.
CLINICAL IMPLICATIONS: The present study not only reconfirms previous findings concerning respiratory function after OPCABG but it also deepens into the pathophysiological sequences of the disturbance.
DISCLOSURE: Panagiotis Behrakis, None.