[Loss of plasma protein in open-heart surgery]

The changes in the concentrations of nine serum proteins were studied in ten patients who underwent open-heart surgery for mitral or aortic valve replacement. alpha 1-glycoprotein, albumin, transferrin, alpha 2-macroglobulin, IgG, IgA, IgM, C3, and C4 were assessed before anesthesia induction, after sternotomy, ten minutes after the beginning of CPB, and ten minutes following the end of CPB; values were corrected for haemodilution. All the proteins, with the exception of alpha 1-glycoprotein, showed similar trends that were characterized by a significant decrease after CPB. Linear contrasts did not show any significant difference among the proteins expressed as per cent of the initial values. Such generalized decrease was probably due to the aspecific damage caused by oxygenators, pumps and aspirators. On the contrary, specific mechanisms, as IgM aggregation or complement activation, do not affect significantly the concentration of single proteins. Also the hypothesis of a relevant protein migration toward the extravascular space was rejected because of the absence of any significant relation between the molecular weight of the proteins and their decrease after CPB.