[Colloid osmotic pressure and extravascular lung water following extracorporeal circulation]

With regard to Starling's equation, two factors are important for fluid regulation in pulmonary tissue: colloid osmotic pressure (COP) and hydrostatic pressure (PCP). The purpose of the study was to evaluate the relationship between COP, COP-PCP-gradient and extravascular lung water (EVLW) immediately after extracorporeal circulation (ECC). 39 consenting patients undergoing elective aorto-coronary bypass surgery received 1000 ml washed erythrocytes (w.e.; cell saver) +400 ml fresh frozen plasma (FFP) after ECC. Additionally, group I (n = 15) received 300 ml albumin 20%, group II (n = 13) 500 ml plasmaexpander (3% HES 200/0.5) and group III (n = 11) no more volume. At three different times, measurement of EVLW was performed by using double-indicator-dilution technique with indocyanine green and a microprocessed lung water computer: 15 minutes after ECC (before infusion), 45 minutes after ECC (after infusion), five hours after ECC. Application of 20% albumin led to a significant increase in COP (+67%) which was less pronounced in group II (+40%) and group III (+41%). Simultaneously, the most pronounced increase in EVLW could be observed in group I (+25%) as well. Pulmonary gas exchange in group I was more compromised (PaO2 -72 mmHg) than in group II (-38 mmHg) and group III (-50 mmHg). No correlation between EVLW and COP-PCP-gradient could be observed. In spite of a significant elevation of COP by using 20% albumin solution, EVLW increased with subsequent deterioration of pulmonary gas exchange. The presented data demonstrate no advantage of albumin 20%; if volume substitution is necessary after ECC, low concentrated plasmaexpanders (up to 10 ml/kg b.w.) may be preferred for several reasons.