Risk factors for low colloid osmotic pressure during infant cardiopulmonary bypass with a colloidal prime

Extensive variations of colloid osmotic pressure (COP) measured in the priming as well as during infant cardiopulmonary bypass motivated us to audit clinical and laboratory data to identify the risk factors for low COP at the end of bypass. Data of 73 consecutive infant patients with body weight <10 kg, who underwent elective, first time open-heart surgery between March 2005 and December 2006 were examined. The following variables were analyzed: COP, blood loss, transfusion requirements and hematological data. Univariate and multivariate analysis of risk factors for low COP (<15 mmHg) was performed. Forty-eight percent of patients had COP <15 mmHg at the end of bypass. Those patients had significantly lower COP before start of bypass, during, and at the end of the operation. Significant univariate predictors of low COP at the end of bypass were: lower patient weight; lower COP before start of bypass, lower priming COP and larger volume of cardioplegia received into the circulation. After multivariable analysis, lower patient COP before bypass remained the only significant predictor for low COP at the end of bypass. Pre-bypass crystalloid dilution during induction should be avoided, as this is the most important cause of low COP during the bypass. Priming COP and COP management strategy should be adapted to the individual patient demand.