Circulatory and metabolic events in pig island skin flaps after arterial or venous occlusion

After 1 hour of arterial or venous occlusion, the circulatory and metabolic events in island skin flaps of the pig were studied. Both occlusion types showed significant but transient increases in glucose uptake and a parallel release of lactate, hypoxanthine, and potassium. Oxygen uptake and noradrenaline release were not significantly affected. No significant difference between the arterial and venous occlusions was seen in the metabolic parameters. The flap blood flow, measured by total venous outflow and laser Doppler flowmetry, was significantly lower after venous than after arterial occlusion. This long-lasting difference in flow response may help to explain the observation that venous occlusion is more deleterious to skin flaps than arterial occlusion. A mechanism underlying these results may be more pronounced microthrombotization and/or edema formation after venous occlusion than after arterial occlusion.     

Vascularized free nail grafts nourished by arterial inflow from the venous system

Three patients underwent successful transplantation of the great toenails to their index fingers using the method of vascularization from venous pedicles. We have found that this procedure is easy and reliable.     

Improved survival of island flaps after prolonged ischemia by perfusion with superoxide dismutase

Perfusion of rat groin flaps after 10 and 11 hours of complete ischemia with superoxide dismutase, an oxygen free-radical scavenger, significantly improved the survival of these flaps. This finding provides further evidence for the important role that oxygen-derived free radicals play in ischemic injury. The study also demonstrates that while restoration of blood supply alone is not enough to ensure tissue survival after prolonged ischemia, chemical agents can be utilized to achieve viable flaps beyond what was believed to be "a point of no return".     

Subcutaneous bipedicle island flaps on the face

Since 1996, 13 patients have undergone the reconstruction of facial skin defects with subcutaneous bipedicle island skin flaps. The reasons for the surgery were basal cell carcinoma in 10 patients and benign skin tumor excision in three patients. All defects were reconstructed with subcutaneous bipedicle skin flaps without significant complications. Bipedicle subcutaneous skin flaps are a useful alternative for facial reconstruction.     

Innervated island flaps in morphofunctional vulvar reconstruction

In this article, the authors present their own experience in vulvar reconstruction following vulvectomy using two different innervated island flaps according to the size and site of the defect. Island-flap mobilization is possible thanks to the rich blood supply of the perineal region. The methods described are a "V-Y amplified sliding flap from the pubis" and a "fasciocutaneous island flap" raised from one or both gluteal folds. The V-Y amplified sliding flap from the pubis is indicated when the defect is symmetric and located anteriorly. This flap is harvested from the pubis and vascularized by the deep arterial network of the pubis. Sensory innervation is provided by branches of the ileo-inguinal nerve. The fasciocutaneous island flap, raised from one or both gluteal folds, can be used following hemivulvectomy or radical vulvectomy, respectively, to cover posteriorly located defects. Vascularization is provided by the musculocutaneous perforating branches of the pudendal artery, whereas sensory innervation is maintained through the perineal branches of the pudendal nerve. Twenty-two patients have undergone reconstructive surgery of the vulvar region from 1989 to date. On 14 patients, a V-Y amplified sliding flap was used; on 7 patients, reconstruction was carried out by island flaps raised from the gluteal fold. Both techniques are compatible with inguino-femoral lymphadenectomy, and they allow for a correct morphofunctional reconstruction and provide good local sensibility. The final result is aesthetically satisfactory, as all final scars are hidden in natural folds.     

Anterolateral thigh fasciocutaneous island flaps in perineoscrotal reconstruction

This study presents the authors' experience using the anterolateral thigh fasciocutaneous flap for complex perineal and scrotal reconstruction. Anterolateral thigh fasciocutaneous island flaps were performed in seven patients between January and June of 2000 (six male, one female; mean age, 52 years; age range, 9 to 72 years). Four of the seven patients had scrotal or perineal defects after multiple debridements for Fournier's gangrene. Two of these four had exposed testicles. Three flaps were used for recurrent ischial ulcers. A true septocutaneous perforator (type 1) running between the rectus femoris and the vastus lateralis muscles was found in only two patients. In four patients, the cutaneous perforators were found to be intramuscular, originating from the descending branch (type 2). In the other patient, the musculocutaneous perforator originated from the lateral circumflex femoris artery independently (type 3). In these cases, intramuscular dissections were performed to follow each perforator to its main trunk. Mean follow-up was 8 months (range, 5 to 10 months), and all flaps survived. Three patients developed minor wound dehiscence in the posterior aspect of the perineal wound because of fecal contamination and skin maceration. Both wounds healed secondarily. Scrotal reconstruction with the anterolateral thigh flap gave an excellent aesthetic result. The authors conclude that the anterolateral thigh flap is a reliable flap for perineoscrotal reconstruction.     

Forefoot reconstruction by reversed island flaps in diabetic patients

Soft-tissue coverage of the foot is often difficult, especially when the distal third of the foot (dorsal or plantar aspects) is involved. The clinical situation can be further complicated when diabetic patients are affected by painful and unstable wounds of this kind because of the familiar phenomenon of vasculopathy. The purpose of this study was to evaluate the possibility of using distally based foot flaps to cover forefoot defects in diabetic patients. Preoperative selection of patients was the key to this study; those who had other major disease, chronic infection, bone involvement, and/or insufficient foot vascularization were excluded from the study. The authors report a series of 12 diabetic patients in whom the reconstruction of medium-sized defects (ranging from 1.5 x 2.0 cm to 3.0 x 7.0 cm) of the forefoot was performed using distally based dorsalis pedis flaps or medial plantar flaps. The transferred flaps survived and adapted well to the defects, except for one flap in a patient who had a slight venous insufficiency at outset. Wearing their own footwear, patients could walk after 20 to 30 days. After the follow-up period (3 months to 3 years), no skin breakdown in the treated areas was observed. Temporary donor-site pain was reported by medial plantar flap patients, and partial skin graft loss at the donor site occurred in some of the dorsalis pedis patients. The authors suggest that in selected cases, medium-sized soft-tissue defects involving the dorsal aspects or the weight-bearing areas of the diabetic foot can be successfully covered with distally based island flaps.     

Arterial blood ketone body ratio as an indicator of the no-return point in hepatic inflow occlusion without venous shunt in dogs

The effects of hepatic inflow occlusion without venous shunt on the viability of the liver were investigated with respect to liver energy metabolism in dogs, subjected to portal triad cross-clamping (Pringle's maneuver) for 10, 30 and 60 min. The concentrations of ketone bodies and the arterial blood ketone body ratio (KBR) were decreased markedly by hepatic inflow occlusion, but recovered upon recirculation. The initial velocity of KBR recovery was 0.150/min after 10-min clamping, 0.140/min after 30-min clamping and 0.032/min after 60-min clamping. KBR recovery was delayed when hepatic inflow occlusion exceeded 30 min, which indicates that hepatic inflow occlusion for 60 min causes severe inhibition of energy generation in liver mitochondria. These findings indicate that the safety period for hepatic inflow occlusion without venous shunt is between 30 and 60 min in dogs, and that mortality can be predicted by measuring the initial velocity of KBR recovery upon recirculation.     

Early circulatory and metabolic events in island skin flaps of the pig

Circulatory and metabolic skin-flap events were studied prior to and up to 6 hours after elevation of buttock island flaps in pigs. During the elevation, significant reductions in superficial skin blood flow, measured by laser Doppler flowmetry (LDF) and dermal flap temperature, were seen. Significant correlations were found between blood flow and temperature. Total flap blood flow, measured as venous outflow, also showed an initial transient decrease, but 2 hours after flap construction, venous outflow had returned to preoperative values. A significant increase in lactate release, together with increased oxygen consumption and glucose uptake, was seen 4 hours after the surgical intervention. Hypoxanthine release, indicating ischemia, was seen only during the first hour after flap elevation. Noradrenaline outflow was noted after 4 and 6 hours, but there was no parallel reduction in flap blood flow. A great deal of the flow reduction in acutely elevated island flaps may thus be due to primary hypothermia rather than to the degenerative release of noradrenaline, which seems to have no early effect on skin flap blood flow. On the other hand, the noradrenaline release may be linked to an increased metabolic activity in the skin flaps.     

Experimental studies of the effects of abnormal venous valves on fluid flow

The effects of variations in the venous valve anatomy are studied experimentally using an artificial system that mimics the bicuspid valves normally found in veins in the lower extremities. The artificial valves are constructed from thin-walled, latex tubing and polyurethane film. The experimental variables in the study are the gap width between the leaflet attachments at the vein wall and the ratio of the sinus depth to vein diameter. The results show that the antegrade mass flow rate is not affected to the same degree when compared to retrograde flow by the various valve configurations examined in this study. The results also indicate that increases in the gap width, which serve to increase the degree of imperfect wall attachment, have less effect on retrograde mass flow rate in valves with deeper sinuses.     

Effect of hyperbaric oxygen and medicinal leeching on survival of axial skin flaps subjected to total venous occlusion

This study evaluates the effect of hyperbaric oxygen and medicinal leeching on axial skin flaps subjected to total venous occlusion. Axial epigastric skin flaps (3 x 6 cm) were elevated on their vascular pedicles in 40 male Wistar rats. Total venous occlusion was achieved by division of all veins draining the skin flap. Arterial inflow was left intact. Animals were randomly assigned to one of five groups: sham (n = 8); control, total venous occlusion only (n = 8); occlusion with hyperbaric oxygen (n = 8); occlusion with leeching (n = 8); occlusion with leeching and hyperbaric oxygen (n = 8). The hyperbaric oxygen protocol consisted of 90-minute treatments, twice daily, with 100% O2 at 2.5 atmospheres absolute for 4 days. The leeching protocol consisted of placing medicinal leeches on the congested flaps for 15 minutes, once daily, for 4 days. Laser Doppler measurements of flap perfusion were recorded preoperatively, postoperatively, and on postoperative days 1 and 3. The percentage of flap necrosis was evaluated on postoperative day 3. Mean percentage necrosis and mean laser Doppler readings were compared between both groups. The flaps in the sham group demonstrated 99 percent survival, whereas the flaps in the occlusion-only group demonstrated 100 percent necrosis. The flaps in the occlusion with oxygen, the occlusion with leeching, and the occlusion with oxygen and leeching groups demonstrated 1, 25, and 67 percent survival, respectively. Sham laser Doppler readings remained within normal limits. Laser Doppler readings in the occlusion-only and the occlusion with oxygen groups decreased to negligible levels on postoperative day 1, and on postoperative day 3 no perfusion was demonstrated. In both the occlusion with leeching and the occlusion with leeching and oxygen groups, there was also a significant decrease in laser Doppler measurements after surgery, but perfusion remained stable throughout the remainder of the study. This study demonstrates that hyperbaric oxygen alone is not an effective treatment for skin flaps compromised by total venous occlusion. The combination of leeching and hyperbaric oxygen treatment of total venous occlusion results in a significant increase in flap survival above that found with leeching alone. It appears that hyperbaric oxygen is effective because of the venous outflow provided by leeching as demonstrated by laser Doppler flow readings.