ABSTRACT
-The aim of this investigation was to follow the metabolism of free TRAM flaps using
microdialysis. Microdialysis is a new sampling technique that provide opportunities
to follow the biochemistry in specific organs or tissues. A double-lumen microdialysis
catheter or probe, with a dialysis membrane at the end, is introduced into the specific
tissue. Perfusion fluid is slowly pumped through the catheter and equilibrates across
the membrane with surrounding extracellular concentrations of low molecular weight
substances. The dialysate is collected in microvials and analyzed by an instrument
using very small volumes.
Glucose, glycerol, and lactate concentrations were measured in the flaps and compared
with those in a reference catheter that was placed subcutaneously in the femur. The
investigation continued 72 hr postoperatively. The study group consisted of 14 women
who underwent reconstruction with a free TRAM flap, and one woman with a double TRAM
flap. During flap ischemia, the concentration of glucose was reduced, while the lactate
and glycerol levels increased. The differences between the flaps and controls were
statistically highly significant. After reperfusion of the flaps, the concentrations
of glucose, lactate, and glycerol approached normal.
One flap failed because of an arterial anastomosis thrombosis. This was clearly demonstrated
by the samples from the microdialysis: the concentration of glucose fell to an unmeasurable
level; the concentration of lactate increased for a period before it stopped due to
lack of glucose; and the concentration of glycerol increased to a very high level,
probably because ischemia caused damage to the cell membranes of which glycerol is
an important part.
The authors concluded that microdialysis can detect ischemia in free flaps at an early
stage, making early surgical intervention possible.
