Editing Wound healing (section)

== Factors influencing wound healing ==
(>90% of ulcers are associated with either chronic venous insufficiency, arterial occlusive disease, or diabetic neuropathy)

=== '''Local''' ===

** Ischaemia
*** '''Inadequate inflow''' - vessel ligation, '''PVD,''' systemic hypotension
**** See separate topics
**** Use WIfI classification to determine severity and guide intervention
**** Toe pressure can be useful in guiding chance of wound healing
**** In general same principles apply as for other wounds - pressure offloading, debridement of non-viable tissue, infection control, moist wound healing
**** Leave adherent eschar or dry gangrene in place until revascularisation has occurred
**** After revascularisation, be aware of limb oedema
***** For grafts ending at popliteal level, below-knee IPC is useful
***** For grafts ending distally, a pedal compression boot is useful
**** Common for infection to develop as areas of eschar/dry gangrene heal - need to be followed closely. Some surgeons prefer to amputate necrotic digits or perform wide debridements of eschar a few days after revascularisation.
*** Dead tissue at wound edge
*** Overly tight or closely spaced sutures
*** Tension on wound edge
*** Smoking - 30% reduction in wound blood flow
** Tension
** Dead space
** Foreign bodies/contamination
** Infection
*** Collagenolysis increases, tissue pressure elevates
*** Mechanical and antibiotic therapy can decrease bacterial count, reduce inflammation, and allow wound closure
*** See separate topic: 'wound infection'
** Haematoma
*** Predisposes to infection and wound complications
** Local trauma
** Chronic tissue factors
*** '''Chronic venous insufficiency'''
**** Venous disease in any combination of anatomic sites may result in limb ulceration, including superficial venous insufficiency alone, however most of the time a venous ulcer is present, there is involvement of the deep venous system (see below)
****
**** Chronic upregulation of pro-inflammatory cytokines appears to mediate the development of tissue fibrosis and the clinical appearance of lipodermatosclerosis (which is believed to be a pre-ulcerative condition). Ulceration eventually occurs secondary to minor trauma.
**** Should have an USS to assess for this (saphenous reflux, perforator incompetence, and iliac outflow stenosis, etc)
**** Sustained high-strength compression of the limb is the basis for treatment of venous leg ulcers, and must be maintained throughout treatment. Results in healing in 60-70% of patients after 4-6 months.
**** Venous intervention is recommended whenever superficial venous reflux is a prominent component of the abnormal venous function. Limited evidence supporting the removal of varicose channels extending into the ulcer bed.
**** Other therapies have been studied including skin grafting, but this is only useful in select cases
*** Lymphoedema, ischaemia, scarring
** Sutures
*** Silk - nidus for infection
*** Too tight?
** Irradiation

=== '''General health''' ===

** '''Diabetes'''
*** Macrovascular disease and microangiopathy
*** Sensory neuropathy - repeated trauma
*** Immunosuppression
** Advanced age
** Malnutrition
*** Vitamin C
*** Vitamin A
** Mineral deficiencies
*** Zinc
*** Iron
** Immunosuppression
** Medications
*** Corticosteroids
*** Chemotherapy
** Smoking 
** Systemic illness