Daily comparison of respiratory functions between on-pump and off-pump patients undergoing CABG

Widespread application of on-pump revascularization procedures is increasing due to the thought of elimination of untoward effects of cardiopulmonary circuit. Thus, whether off-pump coronary artery surgery eliminates side effects especially related to respiratory functions is still controversial. Although many previous studies have evaluated these respiratory functions, daily comparison of 12 parameters was not included in any of the studies. The aim of our prospective study was to ascertain whether off-pump coronary operation improves pulmonary functions and postoperative recovery period when compared with on-pump technique and whether early discharge of patients with off-pump surgery is the result of respiratory improvement.

Eighteen patients in each group were included: on-pump group underwent coronary revascularization with cardiopulmonary bypass and off-pump with stabilization. Respiratory function tests and arterial blood gas analyses were performed preoperatively and daily after operation function tests included forced expiratory volume (FEV) in 1s, forced vital capacity (FVC), expiratory reserve volume, vital capacity, quotient of FEV in 1s to FVC, maximal voluntary ventilation (MVV), tidal volume, and forced midexpiratory flow. Blood gas analyses included partial arterial oxygen and carbon dioxide pressure, arterial pH and hematocrit (Hct).

Preoperative pulmonary functions and arterial blood gases were not statistically significant between groups except MVV and partial arterial oxygen pressure. MVV was slightly higher in on-pump group and partial arterial oxygen pressure was slightly lower in on-pump group. During postoperative first day Hct (P=0.004) and FEV in 1s (P=0.049) values and third day partial arterial oxygen pressure (P=0.011) and Hct (P=0.011) values were lower in on-pump group. Mean extubation, duration in postoperative suit and hospital discharge times, mean blood loss were not statistically significant between groups postoperatively.

Pulmonary functions and arterial blood gases were not improved in off-pump patients when compared with on-pump patients. Patients going to be surgically revascularized should not be altered to off-pump surgery merely with the hope of improving respiratory functions with off-pump technique. As the postoperative stay times at surgical theatre and hospital is not different and the extubation times were similar, early discharge of patients with off-pump surgery cannot be related merely to better preservation of respiratory functions.