The anaesthetist should understand that debridement of the foot is not a rapid procedure such as a usual incision and drainage for abscess, and therefore should anticipate at least 40 min operating time.
• It is important that a meticulous wound exploration is carried out, with removal of infected sloughy tissue and laying open of all sinuses. It is rare to find a well-defined abscess
• The usual presentation is of heavily infected sloughy, grey tissue which needs to be removed down to healthy, bleeding tissue
• All dead tendon and necrotic tissue should be removed (Fig. 5.24). Wide excision is necessary: small incisions with drains should be avoided
• Fragmented infected and non-bleeding bone should be removed
• Deep infected tissue should be sent urgently to the microbiology laboratory
• The wound should not be sutured but left to heal by secondary intention.
• Continue the insulin pump postoperatively until infection is resolving. Then transfer to short-acting insulin three times daily with long-acting insulin at night
• Wound irrigation with a sodium hypochlorite solution (2% Milton) may be useful for the sloughy neuropathic foot. A 1 in 50 dilution of the concentrated 1 % weight in volume solution of sodium hypochlorite is made by adding 20 mL of concentrated sodium hypochlorite to 980 mL of sterile water. Approximately 300-400 mL are irrigated through the wound, making sure to swab the edges of the wound and surrounding skin with normal saline at the end of the procedure to prevent skin drying and irritation. Milton irrigation should be stopped when the wound is no longer sloughy or infected (usually within 5 days)
• We find a simple dressing regime of non-adherent dressing bulked out with gauze and held in place by a tubular bandage is best. It is very quick and simple to lift, and enables regular and frequent inspections to be done.
Signs that the foot is improving include:
• Decrease in erythema
• Reduction of swelling by comparison with the other foot
• Wrinkles will be present in the skin of the foot where oedema has reduced (Fig. 5.25)
• The skin surrounding the previously infected ulcer begins to desquamate or shed and become flaky
• Discharge reduces
• Pain (ifpresent) improves.
When there is an initial fever preoperatively, the patient's temperature is a useful indication of his progress. A steady fall in temperature is expected over the subsequent 3-4 days. If this does not occur, then uncontrolled infection should be suspected. At operation, it is sometimes difficult to remove all infected tissue and a further operative debridement may sometimes be necessary to remove remaining necrotic tissue and control infection. Deep wound swabs or tissue are taken twice weekly to assess the eradication of organisms.
• After surgery, the edges of the wound are debrided every 3 days and all callus, slough and non-viable tissue are removed. The wound is kept open and draining to heal from the base
• Patients will need bed rest and it is wise to give prophylactic subcutaneous heparin. Antithrombotic stockings should not be used on neuroischaemic feet. If they are used on neuropathic feet, they should be folded back from the toe nails to avoid pressure on the nail sulcus
• Patients who have had toe or ray amputations need careful mobilization and rehabilitation. Too rapid mobilization can provoke Charcot's osteoarthropathy.
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