56.3 Amputating for ischaemic gangrene

Deciding where to amputate can be difficult. The lower you amputate, the greater the chance that the patient will walk again afterwards. But there is also more chance that the tissue through which you amputate will not be viable, so that his stump will become infected or gangrenous. Feel his pulses carefully, if you cannot feel his popliteal pulse, do an above knee amputation.

If his muscles do not look healthy when you cut them, abandon the operation at that site, and amputate higher up. Healthy muscle is a nice bright red, and has a good capillary ooze. Ischaemic muscle is a dusky bluish red, and bleeds little or not at all. The tissues of a diabetic are at particular risk, including those of his other limb. So handle the flaps with your fingers, not with forceps. Protect his other limb during the operation so as to make sure that pressure sores do not form. Control his diabetes as in A 17.7.

When you amputate for ischaemia, always close the wound by delayed primary closure (54.4).

Figure 56.7: A GUILLOTINE AMPUTATION. A guillotine amputation is quick, and the flaps are less likely to necrose if the blood supply is poor.