Latent
empyema.—A patient with a latent empyema may be free from
symptoms, and may have been referred for treatment because the signs of an
encysted collection of fluid have been discovered on clinical or radiological
examination. This applies particularly to those cases in which the pus is
sterile as a result of either local or systemic chemotherapy. In other cases
the patient complains of persistent fever, chest pain or dyspnoea following an
acute respiratory infection. Sometimes the patient notices that, after
recovering from an attack of pneumonia, he has not returned to the same state
of vigorous health which he enjoyed before his illness. Then, after an interval
which varies from a few weeks to several years, he may suffer an acute febrile
episode accompanied by pleural pain. If the correct diagnosis is not recognized
and appropriate treatment instituted, these symptoms may gradually subside but
are liable to recur again and again. As long as a latent empyema persists, it
may at any time develop into an empyema necessitatis : the patient will then
complain of a tender swelling in the chest wall.
Persistent
empyema.—A patient with a "persistent" chronic
empyema most commonly complains because there is a continuous or intermittent
discharge from the drainage wound following removal of the tube. Sometimes the
wound heals and remains healed for quite a long time, perhaps for a period of
several years, and then becomes the site of an abscess which is, in fact, an
empyema necessitatis. In other cases of
"persistent" empyema the tube has never been removed, and further treatment is sought because the
empyema cavity does not show signs of undergoing progressive obliteration.
Broncho-pleural fistula.—A latent empyema or an ill-drained persistent cavity
may at any time lead to the formation of a broncho-pleural fistula : the most
prominent symptom is then likely to be cough with purulent, and sometimes
blood-stained, expectoration.
All those affected with chronic empyema are prone to
suffer from lassitude and other symptoms of poor general health.
Signs of
chronic empyema
The complexion of a patient with a chronic empyema is
frequently pale and "muddy", if the septic process has continued
active for more than a month or two. Pleural suppuration almost invariably
leads to clubbing of the fingers and toes, sometimes within a few weeks of the
onset of the infection. Physical signs in the chest include gross flattening of
the affected side, and diminution or absence of movement on respiration. The
classical signs of pleural fluid are usually present over the site of the
empyema. If the empyema is extensive it is common to find that the trachea and
apex beat are displaced towards the affected side, on account of a shift in the
position of the whole mediastinum. In cases of empyema necessitatis, a tender
soft swelling is found superficial to the ribs, and this usually has an impulse
when the patient coughs (Fig. 14).
Radiological
appearances
A "latent" empyema shows as a dense opacity
over which the ribs are approxi-mated. Periosteal new bone on the inner aspect
of these ribs is frequently visible and is pathognomonic of chronic pleural
disease ; it is particularly marked when the infection is caused by actinomycosis.
If the empyema has been drained or has discharged spontaneously, or if a
broncho-pleural fistula has developed, it is common to see a fluid level in the
cavity, in which case it is usually possible to see the thickness of the
fibrous tissue lining the cavity above the fluid level. Skiagrams will also
show the severity of the scoliosis, and the extent to which the diaphragm has
been elevated and the mediastinum shifted as a result of the chronic fibrosis.
The films should be examined carefully for evidence of a foreign body within
the empyema cavity, but, owing to the density of the opacity caused by the
chronic empyema, it is often difficult to see a foreign body even when it is
very radio-opaque, as, for example, with a rib sequestrum.
Special
investigation
If the empyema is not discharging externally, a sample
of the fluid should be obtained by aspiration and sent for bacteriological
investigation. The operator may have difficulty in passing the needle through
the chest wall, because of narrowing of the intercostal spaces, and he must be
prepared to meet with considerable resistance to insertion of the needle, for
the fibrous tissue lining the empyema is often tough. The pus is usually thick,
but it may be quite thin if the fluid has become sterile.
When there is a sinus present or a tube in situ, a
sample of the discharge should be collected in a test-tube and examined
bacteriologically. It is particularly important to search for evidence of
tuberculosis, because the treatment of a tuberculous empyema may differ considerably from that
adopted for a chronic pyogenic case. With this in mind, the granulation tissue
at the orifice of a sinus should be inspected and, if it is pale and
oedematous, which suggests tuberculous infection, a small portion should be
removed for histological examination.
The length of an empyema cavity may be estimated in
cases in which there is a sinus, by passing a fine gum-elastic bougie into it.
If the empyema is still being drained with a tube, the tube should be removed
for a few moments and the patient rotated into various positions in order to
see whether or not the drainage is adequate ; the discharge of a considerable
quantity of pus after removal of the tube is clear evidence that the drainage
provided is inadequate. In those cases in which there is reason to suspect the
presence of intrinsic disease of the lung, such as carcinoma, appropriate
investigation should be undertaken before treatment of the empyema is started.
