Attenuation of Oxidative Stress by Ischemic Preconditioning in an Experimental Model of Intraabdominal Hypertension.

PURPOSE: Increased intra-abdominal pressure, as used in laparoscopic surgery or seen in intraabdominal hypertension (IAH), is associated with tissue ischemia and oxidative stress. Ischemic preconditioning (IP) is a method successfully used in liver and transplant surgery, in order to attenuate the detrimental effects of ischemia and reperfusion. In this experimental study, we tested the ability of IP to modify oxidative stress induced by extremely high intraabdominal pressures. METHODS: Twenty-five female pigs were studied and divided in three groups: a control group, a pneumoperitoneum group (with pressure of 30 mmHg), and an ischemic preconditioning group (initially subjected to preconditioning with pressure of 25 mmHg for 15 min and desufflation for 15 min and then to pneumoperitoneum as in pneumoperitoneum group). Blood samples were obtained at identical time intervals in the three groups. Total oxidative capacity, total antioxidative capacity and total nitric oxide (NO), nitrite and nitrate concentrations were measured and compared between groups. RESULTS: IP increased total antioxidative capacity (p = .045) and protective mediators like nitrite (p = .022). It was also associated with a trend toward lower levels of total oxidative capacity at the end of the abdominal desufflation period but statistical significance was not met. CONCLUSIONS: IP attenuated oxidative stress induced by IAH, mainly by increasing antioxidative capacity and the levels of protective mediators. The fact that IP was effective, even when used at extremely high levels of intraabdominal pressure, reinforces the interest on this method but further studies are needed to clarify its mechanism of action and potential clinical applications.

The impact of ischemic preconditioning on hemodynamic, biochemical and inflammatory alterations induced by intra-abdominal hypertension: an experimental study in a porcine model.

PURPOSE: Intra-abdominal hypertension (IAH) has several pathophysiologic implications on human organs and systems. The aim of this experimental study was to investigate whether ischemic preconditioning (IP), namely the application of IAH for a small period of time prior to establish pneumoperitoneum, can attenuate the hemodynamic, biochemical and inflammatory alterations observed during IAH. METHODS: Twenty-four pigs were divided into three groups: group A (control group), group B (pneumoperitoneum of 30 mmHg) and group C (ischemic preconditioning, consisting of pneumoperitoneum of 25 mmHg for 15 min and subsequent pneumoperitoneum of 30 mmHg). Hemodynamic (central venous pressure, cardiac index, mean arterial pressure, heart rate, stroke volume index, systemic vascular resistance index, global end-diastolic index, intrathoracic blood index and extravascular lung water index), biochemical (serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvate transaminase (SGPT), alkaline phosphatase (ALP), γ-glutamyl transpeptidase (γ-GT), urea and creatinine) and inflammatory (tumour necrosis factor-α, interleukin (IL)-6, IL-10 and C-reactive protein) parameters were measured. RESULTS: (a) Hemodynamics: The increase of central venous pressure monitoring and heart rate and the decrease of cardiac index, mean arterial pressure, stroke volume index, global end-diastolic volume index and intrathoracic blood volume index with the establishment of pneumoperitoneum were attenuated by IP. Systemic vascular resistance index and extravascular lung water were not affected. (b) Urea significantly increased with the pneumoperitoneum. IP, however, attenuated this effect. Οther biochemical parameters (SGOT, SGPT, ALP, γ-GT and creatinine) had a similar upward trend during IAH, which was reversed with IP. (c) Inflammatory parameters: CRP was increased with pneumoperitoneum, an effect that was attenuated with the application of IP. Νo significant differences were observed for interleukins. CONCLUSIONS: Ischemic preconditioning seems to attenuate the pathophysiologic alterations of several hemodynamic, biochemical and inflammatory parameters observed during IAH.