Following microvascular free flap surgery, it is essential to monitor the perfusion of the transferred flap because of the risk of anastomotic failure and ischemia. Monitoring of the flap is commonly made by clinical observation of signs that appear following arterial or venous ischemia.
Microdialysis is a unique technique, which offers the possibility to continuously monitor the metabolism of the flap. Ischemia can be detected by monitoring the changes in Glucose in the interstitial fluid of the specific tissue(1). Microdialysis can reliably detect flap ischemia at an early stage(2).The performance of the analysis is easy and can be done by even less experienced nursing staff working in institutes with a low frequency of microsurgery(2).
Changes in glucose and lactate are sensitive markers of ischemia
When the delivery of Glucose and oxygen is reduced, there is an immediate increase of tissue Lactate and a decrease of Pyruvate and Glucose indicating signs of ischemia. Early detection of flap ischemia allows for early surgical intervention.
Metabolic monitoring offers cost-effective and early signs of complications
A Finnish study(3), published 2009 in the Journal of Reconstructive Microsurgery, studied the costs related to microsurgery during a three year period. A total of 109 flaps were studies with a reoperation rate due to anastomosis in 25% of the cases.
The mean total cost of hospital care was calculated and it was clearly noted that the hospital costs were greatly influenced by surgical complications (i.e., if the primary reconstruction failed, then the secondary microvascular flap almost doubled the expense involved).
Microdialysis was used in flap monitoring and the study concluded that microdialysis provided an early diagnosis of perfusion failure and helped to save the flap. It was estimated that if one or two flaps per year are saved due to more effective monitoring, then the extra costs of using microdialysis are covered.
Microdialysis – the universial flap monitor
Microdialysis is a clinically feasible and sensitive monitoring method for all kinds of micro vascular flaps, especially for those in which clinical observation is difficult or impossible(2). Microdialysis has several advantages compared to other monitoring techniques: objective measurements, different curves for venous and arterial thrombosis and early diagnosis (4). It is a clinically feasible and sensitive monitoring method for all kinds of microvascular flaps, especially for those in which clinical observation is difficult or impossible(2).
We have never lost a flap from neglected ischaemia. Our results show that microdialysis is a safe and reliable technique for postoperative monitoring of intraoral free flaps (5).