Pre-treatment with salicylate completely abolishes the enhanced expression. Several factors combine to facilitate the evolution towards heart and multi-organ failure following cardiac surgery. Some of these factors are related to pure cardiac aspects, for example, the existence of a preoperative heart disease, the use of aortic cross clamping or performance of cardiotomy. It induces a profound hemodilution, which impairs oxygen transport through tissues. This phenomenon becomes obvious in the postoperative period by the existence of increased transpulmonary O2 gradients, extravascular lung water volume and subsequent impairments of O2 transport.
Cardiopulmonary bypass is deleterious by triggering an important inflammatory reaction.
This reaction is largely related to the ratio of the circuit area to the patient's body surface area and is therefore maximal in children. It has been widely demonstrated that the very early paths of this reaction imply several humoral factors including kinins, coagulation factor XII and complement fragments. The activation of these factors is self-amplified and triggers both expression and release of numerous mediators by endothelial cells and leukocytes. The older one is hypothermia that considerably reduces the triggering of the inflammatory mediator network. Heparin-coated circuits may also reduce this reaction to some extent.