[Changes in colloido-osmotic pressure in patients on extracorporeal circulation]

Changes in colloidosmotic pressure (COP) were observed in 15 patients submitted to hemodilution for extracorporeal circulation. Preoperative laboratory tests were within normal limits. COP before hemodilution was above 15 mmHg in 14 cases and 12.6 mmHg in one 9-month-old patient, the mean CP was 18.17 mmHg. During extracorporeal circulation the mean COP decreased to 55% of its initial value (9.92 mmHg). Within the first 4 hrs of the postoperative recovery 13 had COP over 11 mmHg; the remaining two died of cardiorespiratory failure with a COP of less than 7 mmHg. One patient that recovered 100% of its initial COP value between 20 and 24 hrs of the postoperative period had his COP decreased to 6 mmHg and developed fatal pulmonary edema. One patient -who died acute bleeding did not diminish his COP under 12.5 mm Hg. We can conclude that COP lower than 10 mmHg can produce fatal cardiorespiratory failure. Extracorporeal circulation time does not influence the COP recovery. Acute bleeding does not diminish COP values. Hemodilution significantly reduces COP; its recovery and stabilization over 11 mmHg are of prognostic value. COP monitoring is a simple and useful method.