Clinical experience with microdialysis catheters in pediatric liver transplants.

Ischemic vascular complications and rejection occur more frequently with pediatric liver transplants versus adult liver transplants. Using intrahepatic microdialysis catheters, we measured lactate, pyruvate, glucose, and glycerol values at the bedside for a median of 10 days in 20 pediatric liver grafts. Ischemia (n = 6), which was defined as a lactate level > 3.0 mM and a lactate/pyruvate ratio > 20, was detected without a measurable time delay with 100% sensitivity and 86% specificity. Rejection (n = 8), which was defined as a lactate level > 2.0 mM and a lactate/pyruvate ratio < 20 lasting for 6 or more hours, was detected with 88% sensitivity and 45% specificity. With additional clinical criteria, the specificity was 83% without a decrease in the sensitivity. Rejection was detected at a median of 4 days (range = 1-7 days) before alanine aminotransferase increased (n = 5, P = 0.11), at a median of 4 days (range = 2-9 days) before total bilirubin increased 25% or more (n = 7, P = 0.04), and at a median of 6 days (range = 4-11 days) before biopsy was performed (n = 8, P = 0.05). In conclusion, microdialysis catheters can be used to detect episodes of ischemia and rejection before current standard methods in pediatric liver transplants with clinically acceptable levels of sensitivity and specificity. The catheters were well tolerated by the children, and no major complications related to the catheters were observed.

Inflammatory markers sampled by microdialysis catheters distinguish rejection from ischemia in liver grafts.

Rejection and ischemia are serious complications after liver transplantation. Early detection is mandatory, but specific markers are largely missing, particularly for rejection. The objective of this study was to explore the ability of microdialysis catheters inserted in liver grafts to detect and discriminate rejection and ischemia through postoperative measurements of inflammatory mediators. Microdialysis catheters with a 100-kDa pore size were inserted into 73 transplants after reperfusion. After the study's completion, complement activation product 5a (C5a), C-X-C motif chemokine 8 (CXCL8), CXCL10, interleukin-1 (IL-1) receptor antagonist, IL-6, IL-10, and macrophage inflammatory protein 1ß were analyzed en bloc in all grafts with biopsy-confirmed rejection (n = 12), in grafts with vascular occlusion/ischemia (n = 4), and in reference grafts with a normal postoperative course of circulating transaminase and bilirubin levels (n = 17). The inflammatory mediators were elevated immediately after graft reperfusion and decreased toward low, stable values during the first 24 hours in nonischemic grafts. In grafts suffering from rejection, CXCL10 increased significantly (P = 0.008 versus the reference group and P = 0.002 versus the ischemia group) 2 to 5 days before increases in circulating alanine aminotransferase and bilirubin levels. The area under the receiver operating characteristic curve was 0.81. Grafts with ischemia displayed increased levels of C5a (P = 0.002 versus the reference group and P = 0.008 versus the rejection group). The area under the curve was 0.99. IL-6 and CXCL8 increased with both ischemia and rejection. In conclusion, CXCL10 and C5a were found to be selective markers for rejection and ischemia, respectively.

Microdialysis monitoring of liver grafts by metabolic parameters, cytokine production, and complement activation.

INTRODUCTION: The outcome of liver transplantation is steadily improving. Still there is need for earlier detection of complications like hepatic artery thrombosis and rejection. The aim of this study was to explore whether microdialysis with a 100-kDa cutoff filter could be used to monitor local inflammation after liver transplantation. METHODS: Twenty patients undergoing liver transplantations were observed for 1 week posttransplant. Microdialysis catheters were introduced in each liver lobe subcutaneously and metabolic parameters (glucose, pyruvate, glycerol, and lactate), cytokines (interleukin [IL]-6, IL-8, monocyte chemottractic protein-1, and inducible protein [IP]-10), and complement activation (C5a) were measured. RESULTS: Fourteen patients experienced an uneventful course, judged clinically by ultrasound Doppler and by metabolic markers including lactate and the ischemia indicator lactate-to-pyruvate ratio. All patients with uneventful course had a consistent rise in IP-10 from 200 to 3000 pg/mL after transplantation, whereas the other cytokines stayed low. Two patients with rejection showed a selective increase in IL-8 and C5a, starting 2 to 4 days before alanine transferase increased, reaching 10- to 50-fold increase compared with baseline levels, and decreased rapidly after start of antirejection therapy. C5a concentration was substantially increased in these two patients at the time of transplantation. A third patient developed a hepatic artery thrombosis and rejection and showed a rapid rise in intrahepatic lactate and a complex inflammatory pattern. CONCLUSION: Microdialysis using a 100-kDa filter is a promising way of monitoring the inflammatory reaction after liver transplantation. Increase in IP-10 reflects a normal pathophysiologic response posttransplant, whereas IL-8 and C5a were increased only in patients with rejection.