Microdialysis catheters in liver transplants detect vascular complications and rejection
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KeywordsLactate Hepatic Artery Vascular Complication Hepatic Blood Flow Portal Flow
Following liver transplantation, hepatic artery stenosis and portal vein obstruction occur in 3 to 12% of the patients, and more frequently in children than adults. Today, the standard of care is Doppler ultrasound and liver enzyme assessment daily. Accordingly, detection of severe hypoperfusion may be delayed. The aim of the present study was to explore whether microdialysis catheters implanted in the left and right liver lobe, by measurement of glucose, lactate, pyruvate and glycerol every 2 hours, detected vascular complications and rejection.
Seventy-three patients undergoing 82 liver transplantations were included. Nine of the patients were children. Two microdialysis catheters were inserted in the liver and one in subcutaneous tissue by a split needle technique. They were kept for as long as the catheters functioned, and maximally 4 weeks. Metabolic parameters (glucose, pyruvate, glycerol and lactate) were collected every 2 hours and measured bedside.
Median age of the patients was 52 years (6 months to 70 years). The median time for catheters inserted in the liver was 9.5 days, with a range from 0.5 to 26 days. Six patients had hepatic artery stenosis/occlusion, and in five of them lactate increased to values >10 mM with a lactate/pyruvate ratio of several hundred and a concomitant decrease in glucose and increase in glycerol. In one patient (a 6-month-old child) lactate only increased to 2 mM and the LP ratio to 20. On the background of pathological metabolic values, all patients underwent immediate reoperation and blood clots were removed and the artery reanastomosed. In the child with low lactate values, the flow of the artery was less than 10% of total hepatic blood flow, despite reanastomosis. Thus, the exceptionally high portal flow delivered enough oxygen to prevent major ischemia despite very low flow in the artery.
Thirteen patients had rejection verified by biopsy, and in six patients anti-rejection therapy was given based on liver function tests and clinical judgement. All patients had some increase in lactate during the period of rejection, but the increase was in all but four patients only 1 mM. In the remaining four the increase was 3 to 4 mM.
By using microdialysis catheters measuring metabolic parameters, hepatic artery occlusions can be detected very rapidly. Patients with rejection show a small, but significant, increase in lactate.