[Contrast study of cardiac output and oxygen metabolism in infants with congenital heart disease after cardiopulmonary bypass].

Objective: To conduct a contrast study of postoperative cardiac output and oxygen metabolism in infants with congenital heart disease undergoing cardiopulmonary bypass.

Methods: Retrospective analysis was conducted for 55 case of congenital heart disease from January 2006 to January 2009 at our hospital. There were 34 males and 21 females. And they were divided into simple group (n = 30) and complex group (n = 25). In the simple group, all had pulmonary arterial hypertension and there were simple ventricular septal defect (VSD) (n = 15), atrial septal defect (ASD) + VSD (n = 9) and ASD + VSD + patent ductus arteriosus (PDA) (n = 6); in the complex group, there were tetralogy of Fallot (TOF) (n = 12), double outlet of right ventricular with pulmonary stenosis (DORV) (n = 8) and total anomalous pulmonary vein connection (TAPVC) (n = 5). All completed cardiopulmonary bypass procedures under venous injection and inhalation anesthesia. Cardiac outputs were measured by the thermodilution method with a 4 F Swan-Ganz floating catheter at operation completion and postoperative 4, 8, 12, 24, 48, 72 h. Arterial and mixed venous blood specimens were collected through radial artery and floating catheter for blood gas analysis. The parameters of cardiac index (CI), oxygen supply index (DO₂I), oxygen consumption index (VO₂I) and oxygen intake rate (O₂ER) were calculated with PHLIPS M: 8007 A.

Results: (1) At postoperative 8 h, ScVO₂ was minimal (simple group 68% ± 14%; complex group 65% ± 9%); and postoperative 12 h CI (L×min⁻¹×m⁻²) bottomed out (simple group 3.29 ± 0.65; complex group 2.88 ± 0.54); DO₂I (492 ± 153) ml×min⁻¹×m⁻² and VO₂I(138 ± 45) ml×min⁻¹×m⁻² were minimal in complex group. (2) DO₂I, VO₂I, O₂ER and ScVO₂ changed with CI and simple group was higher than complex group. (3) Postoperative CI showed a positive correlation with DO₂I, VO₂I, ScVO₂ and a negative correlation with O₂ER.

Conclusions: The postoperative cardiac output decreases and oxygen metabolism becomes disordered in congenital heart disease. It is most obvious at postoperative 12 h. And complex CHD is more serious. Cardiac output should be actively boosted to improve tissue oxygen metabolism during an early postoperative period.