ABSTRACT
The response of plasma cortisol, corticosterone and non-protein-bound cortisol in the extracorporeal circulation was investigated in 14 patients. The pre-perfusion levels of plasma cortisol, corticosterone and non-protein-bound cortisol were significantly elevated. During and immediately after perfusion, the levels of cortisol and corticosterone were found to decrease significantly from the pre-perfusion levels, while the percentage of non-protein-bound cortisol was shown to increase significantly. This indicates a marked decrease in cortisol binding capacity of plasma during extracorporeal circulation. Moreover in 200 plasma samples, it was demonstrated that the cortisol level increased markedly and the cortisol binding capacity decreased slightly during and shortly after major surgery without perfusion. It is concluded that stressful situations in major surgery with or without perfusion are associated with markedly increased levels of biologically active non-protein-bound cortisol. The elevated level of non-protein-bound cortisol in surgery seems to be dependent on the increase in the level of plasma cortisol as well as on the decrease in the cortisol binding capacity of plasma. Although the increased plasma cortisol plays the most important role in surgery with no perfusion, the decreased cortisol binding capacity may be the more effective factor involved during perfusion.
