Investigation of factors controlling cutaneous circulation in flaps

The aim of this research was to investigate the blood supply to the lower abdomen. This is a commonly used donor site for autologous reconstruction following breast cancer and the flap of tissue used is based on the deep inferior epigastric circulation (DIEP flap) or the superficial inferior epigastric circulation (SIEA flap). A pilot study investigated the feasibility of assessing the vascular territory of multiple blood vessels in the lower abdomen, and also observed the timing of changes in skin blood supply after free flap transfer. Further studies included sampling using microdialysis catheters, from different areas of the flap, around the theoretical time of opening of choke vessels between angiosomes. Manipulation of skin blood flow was initially investigated using capillary malformations as a model, observing current clinical use of EMLA and AMETOP topical anaesthetic pre-laser treatment

High cut-off microdialysis catheters to clinically investigate cytokine changes following flap transfer

Background: ‘Choke vessels’ are thought to dilate in the first 72 h when blood flow to an area is disrupted. This study used ‘high cut-off’ microdialysis catheters in clinical research to investigate factors mediating circulatory change within free flaps. Methods: Six patients undergoing DIEP flap breast reconstruction each had three ‘high cut-off’ microdialysis catheters, with a membrane modification allowing molecules as large as 100 kDa to pass, inserted into Hartrampf zones 1, 2 and 4 to assess multiple vascular territories. Microdialysis continued for 72 h post-operatively. Samples were analysed for interleukin-6 (IL-6), tumour necrosis factor alpha (TNFα) and fibroblast growth factor basic (FGFβ). Results: Three hundred and twenty-four samples were analysed for IL-6, FGFβ and TNFα totalling 915 analyses. IL-6 showed an increasing trend until 36 h post-operatively before remaining relatively constant. Overall, there was an increase (p < 0.001) over the time period from 4 to 72 h, fitting a linear trend. TNFα had a peak around 20–24 h before a gradual decrease. There was a significant linear time trend (p = 0.029) between 4 and 76 h, decreasing over the time period. FGFβ concentrations did not appear to have any overall difference in concentration with time. The concentration however appeared to oscillate about a horizontal trend line. There were no differences between the DIEP zones in concentrations of cytokines collected. Conclusion: This study uses high-cut off microdialysis catheters to evaluate changes in cytokines, and requires further research to be undertaken to add to our knowledge of choke vessels and flap physiology