BackgroundSurgery correction is necessarily required for complete cure of congenital and acquired heart diseases. Introduction of extracorporeal circulation method into practice has allowed to correct small sized atrial septal defects, as well as to compensate large atrial septal defects with synthetic organ or pericardium. The study on acid-base balance during the cardiac correction with extracorporeal circulation to treat heart disorders will allow to control and stabilize acid-base balance, and ensure the normal functioning of organism during the operation. Subsequently, it may serve as basic information for prevention from complications during and after surgery.Materials and MethodsTotally 75 patients who are subjected to cardiac correction of atrial septals defects were involved in the survey. Blood samples were taken in 3 stages (at the beginning, in the process of surgery and at the end) since extracorporeal circulation was established, and subsequently it was determined blood acid-base (ðÍ), blood carbon partial pressure (ÐÑÎ2), blood oxygen partial pressure (ÐÎ2), base excess (ÂÅ) and blood base bicarbonate (ÍÑÎ3).ResultsThe amount of pH and pCO2 contained in blood during the extracorporeal circulation are most likely (p<0.001) differed statistically at the beginning, in the process, and at the ending part. At the beginning and during the process of correction there were revealed sub-compensated alkalosis whereas at the end of procedure there was sub-compensated acidosis. Also under influence of body temperature, the pH and pCO2 are statistically changed.Conclusions:1. Even pH was achieving in normal range before stopping the extracorporeal circulation, there has demand to rearranging system because of there has acidosis and alkalosis are coming out. 2. The buffer system such as pCO2 and BE are working for repairing the repiratory and metabolic alkalosis and acidosis by holding pH in normal range while at the beginning, in the process and at the end in stages of extracorporeal circulation.