The importance of colloid osmotic pressure measurements to prevent oncotic overdosage during cardiac surgery.

OBJECTIVE

Colloidal infusion therapy during cardiac surgery has changed from the principal use of human albumin to the preference for synthetic colloids. Despite the possible interference of synthetic plasma expanders with the biuret determination of total plasma protein (TPP), perioperative infusion therapy is frequently directed on the basis of TPP and albumin levels. The hypothesis that the level of TPP or albumin does not reflect the plasma colloid osmotic pressure (COP) if synthetic plasma expanders are used was studied.

MATERIALS AND

METHODS

In 61 patients undergoing elective cardiac surgery the course of COP and its correlation to the TPP and albumin levels were investigated. Natural and artificial colloids were used for colloidal infusion therapy.

RESULTS

No correlation between TPP/albumin levels and COP was found preoperatively and on arrival at the ICU, only a weak correlation was observed at 24 hours and 48 hours postoperatively. The wide range of the confidential interval indicates that the COP cannot be estimated correctly neither from the TPP nor the albumin level. The postoperative COP was significantly increased compared to the preoperative levels indicating oncotic overdosage.

CONCLUSIONS

In order to avoid oncotic disturbances, indication for colloidal volume replacement during cardiac surgery should be controlled by oncometry if natural and synthetic colloids are administered.