Antinociceptive Modalities on Ischemia Reperfusion Injury

Overview

Postoperative pain caused by surgery-associated tissue injury is a major concern for all the clinical practitioners. Because it affects multiple systems and induces physiological, immunological and psychological changes. Previous literature showed surgical injury induces a systemic inflammatory metabolic-endocrine response that is proportional to the severity of the surgical stress. In surgeries such as liver transplantation, the patients suffer not only from postoperative pain but also an additional oxidative stress caused by ischemia reperfusion. Previous report have proved that an adequate postoperative pain control improves the recovery and reduces the inflammatory cascade by suppression of physiological and psychological stresses. However, the effect of postoperative pain management on ischemia reperfusion injury is unclear so far. In this three year study, we plan to continue our previous study to test the following two hypothesis: (1) postoperative pain exacerbate remote organ injury caused by ischemia reperfusion, (2) the interaction of different antinociceptive modalities on ischemia reperfusion injury.

Our team focused on the study of reperfusion injury in liver transplantation, lung resection and open heart surgeries which need cardiopulmonary bypass. Previous clinical observation showed the increase of lung water in liver transplant recipients. Some patients may even develop pulmonary edema which not only lengthen intensive care unit stay and hospital stay, but also increase morbidity and mortality. In the hepatic ischemia reperfusion animal model, we proved that the release of large amount of reactive oxygen species play an important part in remote lung injury. If propofol, which possesses free radical scavenger property, is given adequately, the production of reactive oxygen species will decrease thus reducing the extent of remote lung injury. In another clinical study, we found that resuming two lung ventilation from one lung ventilation induces a massive superoxide production, which also could be reduced when using propofol for the maintenance of anesthesia. Postoperative pain caused by surgery-associated tissue injury is a major concern for all the clinical practitioners. Because it affects multiple systems and induces physiological, immunological and psychological changes. Previous literature showed surgical injury induces a systemic inflammatory metabolic-endocrine response that is proportional to the severity of the surgical stress. In surgeries such as liver transplantation, the patients suffer not only from postoperative pain but also an additional oxidative stress caused by ischemia reperfusion. Previous report have proved that an adequate postoperative pain control improves the recovery and reduces the inflammatory cascade by suppression of physiological and psychological stresses. However, the effect of postoperative pain management on ischemia reperfusion injury is unclear so far. In this three year study, we plan to continue our previous study to test the following two hypothesis: (1) postoperative pain exacerbate remote organ injury caused by ischemia reperfusion, (2) the interaction of different antinociceptive modalities on ischemia reperfusion injury. In the first part, we plan to use the animal model that we have already established to test if analgesics reduce inflammatory responses and remote lung injury caused by hepatic ischemia and to study if different antinociceptive modalities result in different consequences. In the second part, we will recruit patients receiving liver transplantation, lung resection and open heart surgeries needing cardiopulmonary bypass to study the interaction of nociception and various antinociceptive modalities on ischemia reperfusion injury.