Whether or not multiple venous anastomoses reduce the risk of free-flap failure is a subject of controversy. We report here, for the first time, on the importance of selecting 2 separate venous systems of the flap for dual anastomoses. The efficacy of multiple anastomoses was verified through a retrospective review of 310 cases of the free radial forearm flap transfer. Dual anastomoses of separate venous systems (the superficial and the deep) showed a lower incidence of venous insufficiency than single anastomosis did (0.7% versus 7.5%; P < 0.05). On the other hand, dual anastomoses of a sole venous system showed no significant difference in the incidence of venous insufficiency compared with single anastomosis (11.5% versus 7.5%; P = 0.48). Our results suggest that dual venous anastomoses of separate venous systems is conducive to reduced risk of flap failure and affords protection against venous catastrophe through a self-compensating mechanism that obviates thrombosis of either anastomosis.

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The free radial forearm flap has two drainage veins, the cutaneous and the deep, but no established consensus has been reached on the selection of the drainage pedicle. In our study, the flow volumes of the veins were examined by colour Doppler ultrasonography after 20 forearm flaps had been raised. The volume through the deep vein was significantly higher than that through the cutaneous vein (p < 0.01). In comparing the total flow (both veins open), the flow rate through the deep vein alone (cutaneous vein occluded) was over 80% in 13 cases, 60%-80% in seven, and under 60% in none; that through the cutaneous vein alone (deep vein occluded) was 60%-80% in eight, 40%-60% in eight, under 40% in four, and over 80% in none. Our results show the importance of the deep vein, as indicated by its high drainage capacity from the early stages of flap transfer.

Gel-forming dressings, which absorb the wound exudate to form a non-adherent gel, accelerate wound healing in a moist environment. The most commonly used of these dressings are calcium alginate and hydrocolloid membranes. This study was designed to evaluate the physical properties of these dressings, including fluid retaining ability, gel formation, and the dissolution process to clarify the mechanisms that promote healing. A simple immersion method was used for measurement. This technique was useful for the quantitative assessment of gel-forming dressings and may help to evaluate potential application of these dressings. A comparative analysis showed that alginate dressings remained gelled longer than hydrocolloid dressings. This result was consistent with previously reported clinical features of these dressings. The absence of calcium in wound fluid induced rapid resolution of alginate gel while the presence of a certain concentration of calcium prevented degradation of the gel for as long as one month.