1. Pressure sores are a result of ischemic necrosis of varying depths up to bone which constitutes the internal pressure point. Any part of the bed or a chair usually constitutes such an external pressure point. The necrosis occurs between the two. In reality unless diagnosed very early, a pressure sore reaches the bone very quickly because fat is extremely sensitive to devascularisation.
2. Pressure sores might occur in a matter of hours and not infrequently are the source of toxicity or fever. In fact pressure sores might be missed completely unless nursing care is adequate and the patient is inspected carefully when he is cleaned or sponged. Fever of unknown origin in a bed ridden patient might in fact be the symptom of deep seated, hidden (missed) pressure sore and has all the features of a necrotic, foul smelling abscess when the site is located and drained. While debridement is essential over days, care must be taken not to be too aggressive lest you enter a normal area of hyperemia and cut a vessel. Torrential bleeding can then follow and such an event is difficult to manage in the ward. Also many apparently superficial pressure sores might in fact be deepithelialised areas covering a cone shaped necrosis and need to be examined properly.
3. There is little difference in the way pressure sores are covered with skin flaps as compared to ordinary wounds. However pressure sores in non-sensate skin and those occurring in areas of skin with normal sensation are two entirely different entities. The prognosis of the former is much worse in the long term. The treatment of pressure sores also depends on the kind of patient they have occurred in.
4. In view of the above, pressure sores may be roughly classified as follows so that treatment can be organized.
a. Pressure sores in sensate areas in individuals who become very ill or unconscious but are likely to recover from their illness and will be up and about in a reasonable period, almost always heal spontaneously, rarely requiring skin cover. Pressure sores on the scalp may be an exception because scalp is rigid and will not contract. Here local flaps will usually suffice though large defects have been covered with free flaps.
b. Pressure sores in otherwise sensate areas in individuals in a terminal illness (multi-organ failure, extreme old age) in whom a recovery is unlikely need to have a certain philosophical approach and treatment is decided in consultation with relatives.
c. A group of patients from the above category who will survive their grave illness but will go in to a vegetative state with pressure sores may be treated surgically if adequate nursing care either in the hospital or at home is assured. Deep pressure sores will need flap cover.
d. Pressure sores in non-sensate skin where paralysis of corresponding muscles is present but where protective movements are not completely abolished e.g. in leprosy are best treated with dressings and suitable footwear or protective clothing to the hand. In the foot local flaps are often employed after excision of internal bony pressure points followed by suitable footwear.
e. Pressure sores over non-sensate skin in patients who do not have corresponding muscular paralysis e.g. diabetes can have either occasional surgical treatment such as excision of an offending bony point, debridement or skin graft or conservative treatment with dressings etc. as long as diabetes remains under control. In this group local flaps are notoriously unreliable because microvascular damage is present in surrounding areas (see chapter 9 on wound healing).
f. What is probably the standard example of a pressure sore is one which occurs in a quadriplegic or a paraplegic where both muscular paralysis as well as loss of sensation co-exist. These patients may also have involvement of the urinary bladder and recto-anal dysfunction. The following description mainly concentrates on treatment of pressure sores in this category.
g. The healing of pressure sores in the paralysed is adversely influenced by the fact that the vascular network has become static, having lost its autonomic control. In normal circumstances the lack of blood supply during periods of intermittent pressure will be compensated for by hyperaemia during the time the pressure does not exist. The absence of this natural sequence will not allow good granulation to form around the cone shaped ischemic area. The incriminating bone now gets surrounded by fibrous tissue and the fibrous folds enclose synovial like fluid and this area is then called a bursa.
h. The above pathology of the pressure sore determines the rationale of treatment and therefore includes the excision of the offending bone, a wide area around and including the bursa and also the poorly epithelialised cone of the pressure sore, leaving behind a crater which shows good vascularity. In order that thorough excision is done, the procedure borders on the radical and the surrounding tissue filled with vessels which will not contract in a normal manner can bleed quite heavily and a blood transfusion might be needed. Infiltration with saline adrenaline and the use of a cutting cautery will help. The procedure, though done in a painless area, can occasionally invite shock because the paralysed part of the body has poor compliance vis-à-vis loss of blood and fluids that occurs during surgery. It is advisable therefore to do the procedure with a secure airway and light anaesthetic agents. In any event, close monitoring is very essential.
i. It is generally possible to estimate the size and depth of the crater that your excision will leave behind and if the crater is deep, a musculo-cutaneous flap is usually employed. For shallow craters, a bulky skin flap or a fasciocutaneous flap will suffice. In any plan for any kind of flap it is ideal not to create a secondary defect but should this be inevitable, the plan must be such so as to create a defect in a non-pressure bearing area. Such a defect need not be closed primarily with a skin graft but can be deferred for a few days later.
Photographs courtesy: Parag Sahasrabudhe from Pune.
5. While there have been occasional reports where some flaps have shown greater durability than others for pressure sores in non-sensate areas, the odds are generally stacked against such an outcome. An individual with major paralysis with loss of sensation is a formidable proposition to look after and requires a proper rehabilitation and caring centre. It’s a huge burden on the individual, the family and the state and though in the developed world such facilities exist almost free of charge, the conditions of these hapless victims in our country are pitiable. It is rare that a plastic surgical unit is proximate to a rehab centre even abroad and it so happens that the plastic surgeon is only casually in contact with the patient at the time of the treatment of the pressure sore. After discharge unless the rehabilitation and the care is good, what with the possibilities of debilitating urinary infection, ano-rectal problems and depression, these areas remain vulnerable to repeated ulcerations and can become a frustrating experience. Repeat surgeries are not uncommon and the plastic surgeon must do his best during the time that he is treating the patient.