Reactive oxygen species and adhesion formation: clinical implications in adhesion prevention.

Postoperative adhesion formation is a major clinical problem. It has been demonstrated that the pneumoperitoneum used during laparoscopy is a cofactor in adhesion formation. Reactive oxygen species (ROS) are produced in a hyperoxic environment and during the ischaemia/reperfusion process. ROS activity is deleterious for cells, which protect themselves by an antioxidant system known as ROS scavengers. ROS activity can increase by up-regulation of ROS themselves or by down-regulation of ROS scavengers. Recent data also point to a role for ROS in adhesion formation since the administration of ROS scavengers decreases adhesion formation in several animal models. ROS activity increases during both laparotomy and laparoscopy. During laparoscopy, the pneumoperitoneum determines ischaemia at the time of insuflation and reperfusion at the time of deflation. During laparotomy, the environment has a 150 mmHg partial pressure of oxygen (pO(2)), which is much higher than the intracellular pO(2) (5-40 mmHg). This can explain the increase in ROS activity. The aim of this debate is to open a discussion about the importance of ROS activity, besides the known players and mechanisms involved, in adhesion formation and in adhesion prevention.