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CHAPTER 30
Predilection places of sores in ambulatory patients are the ischial tuberosities pro
duced, in walking cases, mainly by weight-bearing calipers, but more frequently through
negligence on the part of the medical and nursing attendants by not instructing the
paralysed to relieve pressure by lifting himself at regular intervals or by the patient's
own negligence. Other predilection places in ambulant patients are the perineal area and
posterior surface of the penis (produced by urinals), the shins, outer ankles and fifth
metatarsal (produced by pressure against the wheelchair, motor-chair or car), and both
the dorsal and plantar surfaces of the toes, especially in cases of cauda equina lesion or
cord lesion where contractures of the toes occurred in the initial stages by faulty position
ing.
From the mechanism and classification of bed sores given here, it will be apparent
that the old distinction between bed sores and pressure sores is a fallacy, as both result
from the same source—namely, pressure.
PATHOLOGY
The pathological changes in the cutaneous and subcutaneous tissues are determined
by the degree of ischaemia and the virulence and direction of spread of the inevitable
infection along the fascial plane or into the bone. Accordingly, it is possible to distinguish
the following stages in the development of sores.
1. Stage of transient circulatory disturbance.
Pressure has been sufficient merely to
cause erythema of the skin, with some oedema, but without destruction of the tissues.
This pathological condition is reversible and promptly disappears if the pressure is
relieved and gentle massage applied.
2. Stage of permanent damage to cutaneous tissues.
Various types of sores result
from this damage. One is characterized by erythema and congestion of the skin, which do
not disappear after relieving pressure but lead to induration and discoloration of the skin.
In another type, the superficial layers of the skin have been killed and may be excoriated,
exposing the exudating cutis vera. This type resembles an ordinary abrasion. In those
cases in which the dead epithelium remains intact, it is raised by exudation from the
cells of the cutis underneath, and a blister develops, which may be dark in colour if
haemorrhage has occurred (black blister). In a further type, deeper layers of the skin
may be involved, and this results in necrosis and formation of an ulcer after the slough
had been removed. The border of such an ulcer may become pigmented (Fig. 199).
3. Stage of deep penetrating necrosis.
In this stage, the destruction also involves sub
cutaneous tissues, affecting fascia, muscle and bone. The necrotic and highly infected area
is usually surrounded by an inflammatory zone which will only disappear once the slough
is excised and the deep ulcer of the underlying fascia and muscle is exposed, as shown in
Fig. 200. This type of sore usually develops over sacrum and trochanters, and it may
assume enormous dimensions and grotesque shape. There are several varieties of shape:
