Objective: to investigate the feasibility of using microdialysate glucose,
lactate and pyruvate concentrations for grading the severity of blood flow
reduction in patients with critical limb ischemia.
Patients and methods: microdialysis catheters were inserted (two subcutaneo
usly and one intramuscularly) in the symptomatic limb of ten patients. To f
urther reduce limb perfusion, the lower leg was elevated during part of the
experiment.
Results: elevation reduced ankle and toe blood pressure and transcutaneous
oxygen tension. Microdialysate glucose concentration decreased at all three
catheter sites, while lactate increased in the intramuscular catheter. Two
patients interrupted the elevated position prematurely due to severe pain
in the foot. They had among the highest lactate levels in the horizontal po
sition and the most marked increases following provocation. Neither initial
metabolite concentrations nor concentration changes during elevation were
shown to correlate to conventional methods used to assess limb perfusion.
Conclusions: in patients with critical limb ischaemia microdialysis can be
used without complications. A significant decrease in glucose concentration
may reflect lowered blood flow in the elevated position. Metabolic respons
e, i.e. increase in lactate concentration during profoundly reduced limb pe
rfusion was heterogeneous, indicating an overestimation of the presence of
ischaemia in some patients using current diagnostic methods.