Recently there have been many attempts to devise a pharmacological method to increase the survival chance of skin flap.
The experiment was designed to determine whether the pharmacological agents could, in fact, prevent free flap necrosis in rats. Fifty albino rats of both sexes, weighing 200 to 250 g, were divided into five groups, each consisting of 10 rats.
The abdomen was shaved under ketamine anesthesia and the flap measured 8.0cm long from xyphoid process to symphysis pubis in the midline, and 6.0cm wide at the mid-abdomen.
The skin, subcutaneous tissue and panniculus carnosus were incised and were raised from the fascia of the muscles.
With microsurgical technique, free vascularized flap was formed from one groin, while protecting the superficial epigastric vessels.
The femoral vessels were dissected free and the minor branches were transected.
The isolated femoral vessels were severed midway between two Acland microclamps.
The femoral artery and vein were reanastomosed with 10-0 Ethilon suture.
The femoral nerve was divided and not reanastomosed.
The free flap was then secured with running sutures of 2-0 silk.
Reserpine (0.5mg/kg), guanethidine (5mg/kg), phentolamine (5mg/kg) and propranolol (5mg/kg) in 1ml of saline were injected intraperitoneally in each experimental group of animals every 12 hours, starting two days before surgery and continued for 5 consective days after the surgery.
In the control group, the same amount of saline was administered.
All animals were sacrificed on the 7th postoperative day and the surviving area was measured as a percentage of the total flap area.
Biopsies were performed at levels corresponding to viable tissue and nonviable tissue f the free flaps on the 1st and 7th postoperative day.
Examinations were performed to observe the changes of blood vessels of the free flaps on the 7th postoperative day.
The results were as follows:
1. The average surviving area was 50.5±5.1% in control group, 90.4±4.7% in reserpine group, 79.8±11.3% in guanethidine group, 85.4±4.2% in phentolamine group and 65.9±8.3% in propranolol group respectively.
2. The number of blood vessels was markedly increased in the control and each experimental group on the 7th postoperative day compared to that on the 1st postoperative day.
On the 1st and 7th postoperative day, the diameter (μm) blood vessels was 22.7±5.3 and 34.8±4.0 in control group, 43.9±3.4 and 45.4±5.2 in reserpine group, 42.6±3.5 and 43.3±5.7 in guanethidine group, 43.8±4.2 and 44.5±4.8 in phentolamine group and 43.1±3.7 and 43.9±4.3 in propanolol group respectively.
On the 1st postoperative day, the size of blood vessels was markedly increased in each experimental group compared to that in the control group, but there was no statically significant difference between each experimental groups.
3. Microangiographically, the tortuosity, the number and the size of the blood vessels were seen to be most increased in the reserpine group. Through this survival of free flap in rats.
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