Postoperative oxygenation following coronary artery bypass grafting - A multivariate analysis of perioperative factors

Background. Pulmonary oxygenation is generally temporarily impaired followi ng cardiac surgery. We studied the factors influencing postoperative oxygen ation using multivariate analysis. Methods. This study was retrospectively performed in University hospital. F ifty patients undergoing solitary coronary artery bypass grafting were incl uded in this study. Patients were divided into two groups by mean age; olde r group (n = 25) and younger group (n = 25), Alveolar-arterial oxygen diffe rence (A-aDO(2)) and respiratory index (RI) were measured at 3 hours after surgery and on postoperative day 1. Statistical analysis was performed usin g forward selection stepwise regression of 12 perioperative variables. Results. In all patients, A-aDO(2) and RI significantly (p<0.01) increased after surgery and remained high on POD1. in stepwise regression analysis, p reoperative A-aDO(2) and RI were significant factors in the equations for p ostoperative A-aDO(2) and RI in general, which was the most important facto r in the older group. In the older group, preoperative A-aDO(2) or RI and w ater balance were significant (p<0.05) factors which were responsible for h alf the oxygenation impairment just after surgery, and PCWP showed a signif icant (p<0.01) negative correlation with both A-aDO(2) and RT on POD1. In t he younger group, PCWP was a significant (p<0.01) factor for A-aDO(2) and C VP and CI were significant for RI on POD1, Conclusions. Postoperative oxygenation was mainly influenced by the preoper ative respiratory condition, especially in old patients, indicating that pr eoperative management by a physiotherapist may be necessary. Pleurotomy als o had a negative influence. Careful intraoperative and postoperative volume control is important in old patients.