IMMUNOLOGICAL AND PHYSIOLOGICAL-RESPONSES TO AORTIC-SURGERY - EFFECT OF REPERFUSION ON NEUTROPHIL AND MONOCYTE ACTIVATION AND PULMONARY-FUNCTION

Background The aims of this study were to evaluate the effects of aort ic clamping and unclamping on neutrophil and monocyte activation and r elease of plasma mediators in 20 patients undergoing elective aortic a neurysm surgery, and to correlate these findings with pulmonary haemod ynamics and gas exchange. Methods Simultaneous arterial and mixed veno us samples were obtained during and after aortic clamping and unclampi ng. Results Neutrophil respiratory burst activity in mixed venous samp les increased significantly during the period of aortic clamping. An i nitial increase in neutrophil CD11b expression in venous blood 5 min a fter clamp removal was followed by a significant decrease in level of expression. Plasma tumour necrosis factor levels increased at the end of the cross-clamp period and reached a maximum 60 min following reper fusion. There was a significant and sustained rise in plasma thromboxa ne B-2 levels following clamp removal. This increase correlated with t he development of increased pulmonary vascular resistance. Conclusion This study confirms the central role played by activated neutrophils i n the early stages of reperfusion injury and also suggests a role for plasma mediators in mediating cardiopulmonary dysfunction Juring major vascular surgery.