Determination of temporal changes in blood flow in vascularized and nonvascularized nerve grafts in the dog

The time course of revascularization of nonvascularized and vascularized nerve grafts was followed histologically and quantitatively using microspheres in the saphenous nerve of dogs. Nonvascularized and vascularized nerve grafts were created in opposite hindlimbs of each dog. The intravascular presence of India ink was not observed until the third day postoperatively in the nonvascularized grafts, while it was demonstrated in vascularized grafts on the first postoperative day. Control blood flow in undisturbed nerves ranged from 0.06 to 0.16 ml/min/gm dry weight. On postoperative day 1, flow was not detectable in any of the nonvascularized grafts, while vascularized grafts all had increased flow with a mean of 0.73 ml/min/gm dry weight. By day 3, two of six dogs had some measurable flow in the nonvascularized grafts, while flow in vascularized grafts had reached a mean of 1.88 ml/min/gm dry weight. By day 6, blood flow rate had increased to 7.63 and 4.72 ml/min/gm dry weight for nonvascularized and vascularized grafts, respectively. By this avoidance of up to 3 days of warm ischemia, there may be some advantage to vascularized nerve grafts even in a well-vascularized bed.