Capillary measurement of lactate and glucose for free flap monitoring

Background: It is reported that the salvage rate of free flaps is inversely related to the time interval between the onset of pedicle impairments and their clinical recognition. Monitoring of free flaps is therefore of major importance and clinical monitoring remains the most used technique because of lack of low-cost and non-invasive techniques. The authors suggested an efficient, simple and cheap technique to detect early thrombotic events in monitoring free flaps with skin paddle.

Methods: In this multicentre prospective study, measurements of capillary glucose and lactate in the flaps were done. These parameters were compared to standardized clinical monitoring during the first five days. Two sets of data (eventful versus uneventful postoperative period) were analyzed to define the thresholds of lactate and glucose values for diagnosis of pedicle complications, and to establish parameters for this screening test.

Results: Over a period of 19 months, 37 patients were included. With 5 pedicle impairments, complication thresholds were defined as lactate ≥ 6.4 mmol L(-1) and glucose ≤ 3.85 mmol L(-1), in order to obtain a sensitivity of 98.5% and a specificity of 99.5% for the test. Modifications of capillary glucose and lactate measurements appeared in average 5.7 hours earlier than clinical symptoms in pedicle impairments. The mean cost of a five-day monitoring was about 90 USD.

Conclusion: This simple and cheap technique could be used as a routine technique in monitoring free flaps to improve safety of this reconstructive technique.