FIG. 4. Principal instruments used in a microminiature anastomosis. Left to right-Suction immobiliser, three manipulators, Beaver scalpel, two curved Dumont forceps, pattern No. 7, extra fine-pointed Dumont straight forceps, pattern No. 5, foot-operated hydraulic needle holder, made from a Dumont pattern No. 3 forceps, and blood transfusion tubing and chamber.

FIG. 5. Small manipulators and suction tip used to handle vessel edges. Left to right-Double 180 degree hook, single 180 degree hook, right-angle manipulator, 25 gauge needle spoon- tipped suction.

Figure 3 illustrates a mock-up of a double vascular clamp mounted on a stainless steel straight pin. The distance between the clamps can be changed by releasing the small jeweller's friction stop mounted on the pin shaft. The blades of the clamp are held together by small elastic bands. Similar single clamps are used to immobilise the stay sutures depicted in the set-up by a strand of black nylon 0-0005 in. (0-01 mm.) traversing the centre of the double clamp. The instrument in the lower right-hand corner of the illustration is a needle holder mounted with a 0-003 in. (0-06 mm.) needle which is threaded with 0-0005 in. (0-01 mm.) green nylon. Figure 4 depicts the principal instruments used in microminiature anastomoses. The forceps are high-quality stainless steel with durable accurately aligned tips. Such instruments are widely used in the jewellery, watchmaking, and electronic assembly field.1 The curve type forceps are ideal for handling and tying sutures. A hydraulic release mechanism is incorporated into the needle holder on the right to eliminate the unavoidable, uncontrolled movement produced at the points by any manual release mechanism. The small Beaver blade 2 is helpful in dissecting out the vessel. Figure 5 is a close-up of the various instruments used to handle vessels. They permit complete atraumatic manipulations of the vessel ends and eliminate the crushing effect of forceps. The single hooks, double hooks, and angulated manipulators are made from highly tempered steel which is etched down electrolytically to microfine points. They are then soldered into 30 gauge or 27 gauge hypodermic needles which serve as intrument heads.

Technique.-Adult doe rabbits weighing 5 to 7 lb. were used. Anaesthesia was produced by intravenous nembutal 60 mg. per ml. An initial dose of 10 mg. per lb. was given through a pediatric-scalp-vein apparatus into the marginal vein of the ear not being operated upon. The needle was left in place for supplemental injections, since the procedure initially took three to four hours' time.

The central artery and vein were dissected free under low magnification using the Zeiss operating microscope. All adventitia was carefully removed from the section to be transected. At this point a millimetre rule was placed under the vessel and a photograph taken recording the vessels' exact outer diameter. The vessels were then cut across obliquely (Jacobsen, 1963) and the ear amputation completed.

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