Can venous saturations from the central venous line and the venous side of the heart–lung machine be interchangeable with mixed venous saturation from the pulmonary artery in children undergoing open-heart surgery?

Abstract

Background Mixed venous oxygen saturation has been advocated as an indirect index of tissue oxygenation. This study evaluated whether venous oxygen saturation from the central venous line (CVL) or the venous side of the cardiopulmonary bypass (CPB) was interchangeable with mixed venous oxygen saturation from the pulmonary artery in children undergoing cardiac surgery for correction of congenital heart defects. Patients and methods Forty children ranging in age from 1 to 15 years undergoing correction for congenital heart procedures with CPB were included in this study. Simultaneous samples were taken from the CVL, the pulmonary artery, and from the venous side of the CPB after 10 min on full CPB and at the end of surgery before weaning from CPB. Bland and Altman’s analysis was carried out to study the agreement between different venous oxygen saturation. Results Insignificant correlations were observed between venous oxygen saturation from the pulmonary artery, the CVL, and the venous site of the CPB. Wide limits of agreements were observed between the venous oxygen saturation in the pulmonary artery with that in the CVL (14.21–−15.32), and also with that in the venous side of the CPB (34.34–−33.18). A wide limit of agreement was observed between venous oxygen saturation in the venous side of the CPB with that in the CVL (28.24–−31.67). Conclusion Venous saturations from the CVL, and from venous side of CPB are not interchangeable with mixed venous saturation from the pulmonary artery in children undergoing open-heart surgery.