Pulmonary hypertensive response to declamping of the aorta during abdominal aortic reconstructive surgery-role of metabolic derangement and anaphylatoxin in the reaction.

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Metabolic parameters and anaphylatoxin activities in mixed venous blood were measured in 16 patients undergoing abdominal aortic reconstructive surgery to study the mechanism of pulmonary hypertensive response after aortic declamping. This reaction was confirmed by a rise in ratio between mean pulmonary arterial pressure and mean systemic arterial pressure (Pp/Ps). Aortic declamping was followed by a significant increase in lactate level and lactate-pyruvate ratio (L/P ratio) as compared with pre-declamping level ( P << 0.01). Although anaphylatoxin C3a concentration rose significantly after declamping ( P << 0.01), C5a showed no change at any stage. When the patients were divided into two groups according to the degree of Pp/Ps change by declamping, significant elevation of L/P ratio and C3a level were observed in the group with higher increase (Post-/Pre-declamp value >/=1.25) of Pp/Ps compared to the lower (>>1.25) group. After declamping, in the higher Pp/Ps group, a positive correlation existed not only between Pp/Ps change and aortic clamp time, but also between L/P ratio and C3a level. The present results suggest that muscular metabolic derangement distal to the aortic clamp may play an important role in the development of post-declamping pulmonary hypertensive response through anaphylatoxin C3a.