Microdialysis in Clinical Practice

Abstract

Clinical examination is still the gold standard of postoperative free flap monitoring, but with intraorally situated and/or buried flaps, it can be difficult or impossible. Microdialysis is a sampling technique which offers the possibility to monitor the metabolism of a flap continuously. Ischemia can be detected by monitoring the changes in glucose, lactate, and pyruvate levels in interstitial fluid of the specific tissue. Our aim was to use microdialysis to monitor the metabolism of free flaps used for reconstructions inside the oral cavity/oropharynx and to evaluate the reliability and usefulness of this new monitoring method.Twenty-five consecutive patients who underwent oral cavity/oropharynx cancer resection and immediate reconstruction with free flap were included in the study. A microdialysis catheter was placed into the subcutaneous adipose tissue of the flap in the end of the surgical procedure. Dialysate samples were taken on an hourly basis for 72 hours postoperatively. Routine clinical monitoring was carried out by experienced nursing staff. Clinical findings were recorded and later compared with microdialysis values. Two flaps out of 25 failed in spite of reoperations. In both problem cases, microdialysis indicated ischemia 1 to 2 hours before it became clinically evident. During flap ischemia, the lactate/pyruvate ratio increased, glucose concentrations reduced, whereas lactate level increased when compared with normal values. Our results indicate that microdialysis is safe for the patient and the flap. It can reliably detect flap ischemia at an early stage. This is especially useful in buried flaps when clinical monitoring is difficult. Microdialysis may also reduce the patient discomfort caused by repeated clinical examination of the flap.

Role of Lactate Measurement in Flap Monitoring: An Useful Adjunct

“…This allows for continuous measurement and excellent objectivity especially for buried flaps, but at the same time is a complicated procedure and needs an experienced personal for its management. 11 Our study cited the major advantage of this instrument as its ability to measure capillary lactate very quickly and easily.…”

Continuous Interstitial Glucose Measurement for Flap Venous Occlusion Monitoring in a Diabetic Model

“…Similarly, a previous study using microdialysis to monitor intraoral free flaps found that the glucose values fluctuate after insulin injection in some diabetic patients. 10 For patients using insulin, the effectiveness of this flap interstitial glucose monitoring method requires further verification. The systemic glucose instability needs to be closely and continuously monitored after surgery.…”

“…[2][3][4] Monitoring based on instruments includes laser Doppler flowmetry, 5 transcutaneous oxygen tension, 6 color Doppler ultrasonography, 7 tissue pH, 8 and near-infrared spectroscopy. 9 Among these monitoring methods, microdialysis is highly sensitive to arterial ischemia and venous congestion through metabolic changes in flaps 10,11 however, as microdialysis involves high costs, a complicated operational procedure, and potential catheter displacement, the clinical application of this technique is limited. To simplify the microdialysis technique, flap local glucose measurement is considered a simple and practical method with low cost and easy access.…”

Quantifying the Limitations of Clinical and Technology-based Flap Monitoring Strategies using a Systematic Thematic Analysis

“… 46 In the case of microdialysis, the catheter may become dislodged on movement or if not secured properly, leading to false readings. 47 , 48 Strict perioperative care is required to limit the occurrence of equipment malfunction. The limitation of complex operative technique is almost exclusively associated with the use of the implantable Doppler device.…”