[Microdialysis monitoring of a free omentum flap]

Microdialysis allows postoperative monitoring of free flaps. It allows determining their cellular metabolism in vivo by measuring glucose, lactate, and pyruvate. We report an application on a greater omentum free flap.

A 77 year old female patient was operated for a vertex angiosarcoma. A large loss of vertex substance (175cm(2)) was rebuilt with a greater omentum free flap. Monitoring included hourly clinical observation (color, temperature, aspect), and flap surveillance using microdialysis CMA 60((R)) catheter. The first value was obtained 1h 30 after revascularization. The following recordings were made every hour for 48hours, then every 2hours for the next two days, then every 4hours. The following parameters were assessed: glucose (G), lactate (L), and pyruvate (P). The lactate/pyruvate (L/P) ratio was calculated after each dosage. Critical and alert values were the same as for other types of flaps. The first values for G, L, P, and L/P were respectively: 0.92mmol/l, 0.92mmol/l, 72micromol/l, and 13. The mean G, L, P, and L/P values were respectively: 5.9mmol/l, 6mmol/l, 269micromol/l, and 22. The values corresponding to a stable metabolism were obtained on the first postoperative day with the following mean G, L, P, and L/P values of: 5.9mmol/l, 5.3mmol/l, 256micromol/l, and 21. Surgical evolution was uneventful.

In cervicofacial reconstruction, the greater omentum free flap is often associated to a gastric strip (gastroepiploic flap) and either greatly or completely covered. It is thus little accessible to postoperative clinical surveillance and ischemic complications may be overlooked and compromise the flap's survival. Complementary surveillance techniques such as microdialysis are necessary.