Alterations in plasma phosphorus, red cell 2,3-diphosphoglycerate and P₅₀ following open heart surgery

Objectives. To evaluate changes in and the correlation between plasma phosphorus, red cell 2,3-diphosphoglycerate (DPG) and adenosine triphosphate (ATP), and P₅₀ in children following heart surgery. Experimental design. Prospective, observational study with factorial design. Setting. A pediatric intensive care unit in a university hospital. Patients. Twenty children undergoing open heart surgery for congenital heart defects. Interventions. None. Measures. Red cell 2,3-DPG and ATP, P₅₀, plasma phosphorus, and arterial lactate were obtained before and at 1, 8, 16, 24, 48, and 72 hours after surgery. The amount of intravenous fluid and glucose administered, and age of blood utilized were documented. Variables were analyzed by repeated measure analysis of variance followed by paired t-tests. To investigate the relationship between variables at each time point, scatter-plot matrices and correlation coefficients were obtained. Results. There was a reduction in plasma phosphorus, red cell 2,3-DPG, and P₅₀ and an increase in arterial lactate at 1, 8, 16, 24, 48, and 72 hours after surgery. Red cell 2,3-DPG correlated with P₅₀ at 1, 8 and 16 hours. The decrease in the plasma phosphorus correlated with the amounts of intravenous fluid and glucose administered on the day of surgery and on the first and second postoperative days. The age of the blood utilized correlated with the decrease in red cell 2,3-DPG on the day of surgery. Conclusions. Reduction in red cell 2,3-DPG, P₅₀, and plasma phosphorus occurs after open heart surgery in children. These changes can potentially contribute to impaired oxygen utilization in the postoperative period, when adequacy of tissue oxygenation is critical.