No abstract

In microvascular tissue transfers, it is essential postoperatively to follow-up on the perfusion of the transferred flap because of the risk of anastomotic failure. The diagnosis of pedicle obstruction is usually made by clinical observation, but some techniques have been reported as more reliable than clinical observation in detecting perfusion failure. The authors used microdialysis (MD), a method developed to assess in situ tissue metabolism, in the follow-up of 80 consecutive microvascular flaps from October, 2001 to October, 2003. Of the 78 flaps with postoperative data, 58 flaps were uneventful clinically and using MD, and served as the reference material for normal postoperative metabolism. Twenty flaps showed some abnormality in the clinical course or with MD. Of these, 13 flaps were reoperated for anastomosis thrombosis (9 arterial, 4 venous). All thromboses were clearly recognized by MD via a decrease in the glucose concentration in the tissue (< 2.7 mmol/l) and an increase in the lactate concentrations (> 5.7 mmol/l). In some cases, MD indicated a pathological trend in glucose and lactate concentrations hours before there were any clinical signs. A system of alarm levels was developed for the staff: when the limits were reached, a critical evaluation of the situation was undertaken, and the need for reoperation was considered. In the series, the salvage rate of all thrombosed flaps was 77 percent, with a final success rate in microvascular reconstruction of 95 percent. No flap was lost due to a delay in the diagnosis of secondary ischemia, if on-line MD monitoring was available. Microdialysis 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. 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.

Early diagnosis of postoperative perfusion failure is essential in microsurgical tissue transfer. In order to determine if microdialysis could be used in diagnosing flap ischemia, we tested this method in an experimental pig model. Sixty-six flaps (34 myocutaneous and 29 cutaneous) were created in 18 anesthetized pigs. During the experiment, secondary ischemia was induced for 5 h by selective clamping of the artery (20 flaps) or vein (21 flaps). Glucose, lactate, and pyruvate concentrations were measured hourly from the muscular and dermal layers. We found that decreasing glucose levels and increasing lactate concentrations were associated with arterial and venous occlusions from the first hour of ischemia. In venous ischemia, lactate concentrations remained lower than those in arterial ischemia. The increase in lactate-to-pyruvate and lactate-to-glucose ratios was related to ischemia and also discriminated arterial occlusion from venous occlusion. In conclusion, microdialysis can be used to facilitate early detection of ischemia.

Summary A retrospective analysis of 321 gastric cancer patients was made to assess the prognostic value of TNM classification, tumour differentiation, Lauren classification, proliferative rate, inflammatory reaction and tumour invasion in vascular or neural structures of the gastric wall. The TNM classification showed the strongest correlation with survival in univariate and multivariate analyses (P<0.0001). The invasion in lymphatic or vascular system and Lauren classification were also independent prognosticators in multivariate analysis (P<0.05). In univariate analysis, the WHO-grade, the size and the location of the tumour and perinueral invasion were significant prognostic factors (P<0.01), as were the infiltration of lymphocytes and plasma cells in the tumour (P<0.05). On the other hand, the mitotic indices reflecting the proliferative activity of the tumour cells showed no significant correlation with the prognosis. The results indicate that the prognostic power of the TNM classification can be further increased by assessment of the above special histological features in gastric cancer.

Few studies have examined the cost-effectiveness of microsurgery, and little is known about the cost-effectiveness of flap monitoring. We studied the costs related to microsurgery during 2004 to 2006 in Kuopio University Hospital. A total of 99 patients were reconstructed with 109 flaps. Primary success was achieved in 64% of cases. Reoperation for anastomosis was conducted in 25% and for other surgical complications in 27%. The intended result was achieved in 94% of cases. The mean total cost of hospital care was 20,000 euro in head and neck cancer surgery, 15,500 euro in defects of the lower extremities, and 9200 euro in breast reconstruction. The costs were greatly influenced by surgical complications (i.e., if the primary reconstruction failed, then the secondary microvascular flap almost doubled the expense involved; mean expenses per case 27,900 euro). Microdialysis was used in flap monitoring with an additional cost of 535 euro per patient. We found 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.