New PhD on "Intraorgan monitoring for detection of ischemia and rejection"

On December 7th 2011 Lars Wælgaard, MD defended his thesis on Intraorgan monitoring for detection of ischemia and rejection. Lars Wælgaard's work originates from The Acute Clinic, Department of Anesthesiology and Intensive Care Medicine, and The Intervention Centre, and Institute of Clinical Medicine at University of Oslo.On the image from left: 2. opponent: Professor Petter Aadahl, Institutt for sirkulasjon og bildediagnostikk, NTNU, Trondheim,1. opponent: Professor Bo-Göran Ericzon, Transplationskirurgiska kliniken, Karolinska Universitetssjukhuset, Huddinge, Stockholm, mentor professor Tor Inge Tønnessen, Department of Anesthesiology and Intensive Care Medicine and to the right Lars Wælgaard.

Abstract: In a clinical setting compromized blood perfusion or inflammation in single organ systems may threaten organ function and thereby the whole organism. Occult bleeding from internal organs may be difficult to diagnose by global monitoring. Much because of lack of reliable intraorgan measure methods deaths because of ischemia from different reasons like trauma, postoperative bleeding from insufficient vascular annastomoses or other causes , thromboses, hypovolemia, hypoxia or infection are major problems in daily intensive care medicine. Patients undergoing organ transplantation are in addition threatened by graft rejection, which may be difficult to diagnose in time.
In an experimental study on hemorrhagic shock in pigs significant differencies in distribution of flow to the different organs were revealed. In evaluating intraorgan monitoring of different metabolic parameteres and tissue gases, we found that partial pressure of carbon dioxide (pCO2) can be used as a marker of tissue hypoperfusion both under aerobic and anaerobic conditions. Compared to other metabolic markers it gives an earlier warning of hypoperfusion and increases early at the onset of tissue anaerobiosis.

The use of microdialysis was evaluated as a means to measure metabolic parameters but also relevant inflammatory mediators after liver transplantation. Recovery of different inflammmatory components including cytokines and complement activation factors were shown in an in vitro study. By using intraorgan monitoring with microdialysis catheters in patients undergoing liver transplantation both thrombosis of the liver artery and acute rejection were detected several days before standard monitoring methods.These findings have later been confirmed in a larger study by or group.
Microdialysis may be used in virtually any organ system, and may become a valuable tool in monitoring after orthopedic replantation surgery, surgery on internal organs and in patients with cerebral thromboses or bleeding.