Pus in the pleural cavities[md]empyema

Pus usually reaches a patient's pleural cavity from infection of the lung under it. This can be pneumonia, a lung abscess, or the pneumonitis that may follow an inhaled foreign body (usually in a child), or carcinoma of the bronchus (usually in a cigarette smoker). Occasionally, an empyema is tuberculous; rarely it may follow rupture of a liver or subphrenic abscess through the diaphragm.

A common history is that a week or more ago, as the patient was beginning to recover from a chest infection, improvement stopped. He now remains ill, anorexic and febrile, and is starting to lose weight[md]despite antibiotics.

Many kinds of bacteria can be responsible, but pneumococci are perhaps the most common. Antibiotics are only effective in the earliest stages, and may mask the symptoms of an empyema later. The result is that empyemas can remain undetected for years and are often missed in a busy outpatient department. This is sad because you can treat them, so watch for them, and ask your staff to do so too.

Pus in the pleural cavity, like pus anywhere else, must be removed. To begin with it is thin, like serum; later it thickens and looks like scrambled egg. So adapt your method of removing it to its thickness. While it is still thin, aspirate it with a syringe and needle. When it is too thick for this, but is still fluid enough to flow down a tube into a bottle, use closed drainage, as if you were draining blood from an injured chest (65.2). The surfaces of the patient's pleura will not have stuck together at this stage, so you will have to use an underwater seal to prevent air getting into his pleural cavity and letting his lung collapse.

If the pus in his pleural cavity is left undrained, it will soon become too thick to flow down a long thin tube into a bottle. Once his empyema has reached this stage, only thoracotomy and decortication will properly expand his lung, but this is a dangerous operation, even in expert hands. If referral is difficult, you can improve him greatly by draining pus through an open drain. To do this you will have to remove a piece of a rib and push a short wide tube through its bed. The surfaces of his pleura will now have stuck so firmly that air cannot enter his pleural cavity to collapse his lung. When you do this be sure to: (1) Remove the piece of rib from inside its periosteum, so as not to injure the vessels and nerve which run just below it. (2) Place the inner end of the tube where the bottom of the abscess cavity will be while he sits in his usual position in bed.

If the pus in his pleural cavity remains even longer it will be replaced by fibrous tissue which will be very difficult to remove.

Children have special problems. In a child an empyema may follow a post-measles pneumonia, or the rupture of a staphylococcal lung abscess into a pleural cavity. He is likely to be between 1 and 3 years, malnourished, anaemic, and anorexic, with a persistent cough, fever, dyspnoea, diarrhoea, and perhaps vomiting. He may be very sick indeed with a pyopneumothorax under tension. Treat him as you would an adult.

ASPIRATOR, Martin's, with 3-way tap and needles, one only. This is much the best instrument for draining large quantities of fluid from the chest. It has a tap, so that you can aspirate pus and discharge it through a tube into a receiver, without letting air enter the chest.

Fig. 6-1 THE ANATOMY OF THE PLEURAE. A, the relation of a patient's pleurae and lungs to his chest wall. B, a coronal section of his thorax (semischematic). C, the ventral aspect of his thorax showing the surface projections of his heart and pleurae. D, the subdivisions of his mediastinum.

1, the horizontal fissure. 2, the oblique fissure. 3, the inferior border of the right lung. 4, the costodiaphragmatic reflexion of the right pleura. 5, the costodiaphragmatic reflexion of the left pleura. 6, the cardiac notch of the left lung. A, Fig. 8.23B and C, Fig. 8.23A from ''Gray's Anatomy' (Churchill Livingstone). B, Fig. 6.6 and D, Fig. 6.8 from Grant's ''Method of Anatomy' (9th edition 1975 edited by JV Basmajian). With kind permission.

EMPYEMA CLINICAL FEATURES. If an empyema involves the whole of a patient's pleural cavity and contains a litre or more of pus, you should be able to diagnose it clinically. Look for limited movement of his chest on the affected side, shifting of his trachea and apex beat, dullness to percussion, reduced breath sounds and reduced vocal fremitus. Vocal resonance (the sound ''99'') may be high-pitched at the top of the empyema and absent over its lower part.

X-RAYS. usually show a dense area at one lung base. Take a PA and a lateral to show the site and extent of the empyema.

ANTIBIOTICS. When an empyema is established, antibiotics are ineffective. Pus must be drained. If he has fever or malaise give him chloramphenicol (2.7) until sensitivity tests show the need for change.

ASPIRATING [s7]A PLEURAL EFFUSION INDICATIONS. (1) To confirm the diagnosis. (2) To remove the bulk of the fluid in the early stages while it is still thin.

EQUIPMENT. A Martin's aspirator, with its needles and 3- way tap, a 20 ml syringe, local anaesthetic solution and a receiver. Or, improvise the equipment in Fig. 65-8.

METHOD. Premedicate the patient thoroughly an hour before. If he is not very ill, sit him astride a chair leaning over a pillow on the backrest. If he is very ill, sit him in bed with his arms folded, leaning over a bed table or a pile of pillows.

Aspirate near the lowest point of the empyema, as defined on the PA and lateral X-rays. To establish this, aspirate several sites if necessary, so as to find the lowest site that yields pus, but remember the surface markings of the pleura (9-4a). Commonly, the posterior axillary line is the right vertical line in which to aspirate.

Infiltrate anaesthetic solution into his skin and subcutaneous tissues over the chosen space, and also a space above and below[md]you may have chosen the wrong one.

Insert the needle, pierce his pleura and aspirate gently; turn the tap and discharge the fluid into a receiver. If you don't have a 3-way tap, and have not improvised the equipment in Fig. 65-8, you can (less desirably) put your finger over the hub of the needle, as you disconnect the syringe to discharge it.

Repeat the aspiration 2 or 3 times a week until pus stops forming, or it becomes too thick to aspirate.

CLOSED DRAINAGE [s7]FOR A PLEURAL EFFUSION Many empyemas do not resolve on aspiration alone. If pus thickens, so that aspiration is even a little difficult, closed drainage is necessary. Insert an underwater seal drain, as for a haemothorax (65.2). Leave it for a least two weeks until firm adhesions have formed between the surfaces of his pleura, which will prevent his lung collapsing when you take the tube out. The instillation of 5 to 10 g of lipiodol before repeat X-rays is a useful way of defining the lowest point of the empyema.

If he improves, and X-rays show disappearance of the empyema and re-expansion of his lung, cut the stitch securing the tube, pull it out and quickly press an airtight dressing over the hole.

If he does not improve, he needs open drainage or referral.

Fig 6-1a STAGES IN THE DRAINAGE OF PUS IN THE PLEURA. A, a very recent pleural effusion can be drained with a syringe and needle. B, if pus becomes too thick for this, you will have to use a rubber tube and an underwater seal drain in a bottle (closed drainage). C, if pus becomes even thicker, resect the patient's rib, and insert a short wide tube (open drainage). Shorten this tube as his empyema drains, and make sure it is in the bottom of the cavity. D, if you fail to drain an empyema, you may have to refer the patient for decortication.

OPEN DRAINAGE [s7]FOR AN EMPYEMA, RESECTING A RIB INDICATIONS. Draining an empyema when closed drainage has failed. The patient's lung must have stuck to his ribs. (1) The traditional pre-antibiotic test was to put some of the fluid in a test tube; if the sediment was approximately half the volume of the fluid, it was safe to insert an open drain. Antibiotics make this test less useful, because the fluid is more likely to remain thin. (2) Slowly withdraw the tube of the underwater seal drain from the water. If the column of water does not run up towards the pleura, but stays in the tube, his pleura has stuck to his ribs, so that an an underwater seal is unnecessary and open drainage can start.

CONTRAINDICATIONS. A tuberculous empyema. See below under empyema necessitans.

X-RAYS. Examine PA and lateral views with the greatest care to see which rib to resect. If you cannot easily see the lowest point of an empyema, inject 10 ml of oily contrast medium before you take the films.

ANAESTHESIA. Take him to the theatre. Premedicate him well (A 5.2). Use a combination of local infiltration (A 5.4) and intercostal blocks (A 6.7). Block his intercostal nerves at the site of your chosen incision, and also one rib above and one below it as far back as possible.

METHOD. Drain his empyema from its lowest point, in the position he would be in while he sits in bed. Since he lies more supine than prone, choose the lowest point of the empyema posteriorly. Often, his 9th rib in the paravertebral line is the best, but it may be below this.

CAUTION ! Don't make the opening too low, because his diaphragm will rise as the pus drains and block the opening. It should always be at least one space abve his diaphragm.

Sit him on a stool leaning forwards against the operating table. Before incising, confirm by aspiration through more than one intercostal space, that you have chosen the correct rib to remove. Make an 8 cm vertical incision, extending above and below the selected rib, so that you can more easily resect the rib on either side if necessary.

Cut down to the rib, and incise the periosteum along its centre. Use a curved Faraboef rougine to strip the periosteum with its attached intercostal muscles from the outer surface of his rib. Clean its upper and lower borders. Then use Doyen's raspatory (or Faraboef's rougine) to remove the periosteum from its inner surface. Strip its upper and lower borders as in Fig 6-2.

CAUTION ! (1) The intercostal blocks should have anaesthetized his parietal pleura adequately; if they have not, repeat the intercostal blocks and wait. If you fail to anaesthetize him adequately, extreme pain may cause vasovagal shock. (2) His intercostal vessels can bleed severely if you fail to identify them, so be sure to avoid them by keeping inside the periosteum.

Excise a 5[nd]10 cm length of rib with an osteotome, rib shears, or a large pair of bone cutters. Make an incision in the bed of this rib through into his pleural cavity. Open it with a haemostat, explore it it with your finger, and remove what semisolid pus you can with sponge holders. He will probably start coughing.

CAUTION ! (1) If when you explore the cavity with your finger, you find that you have not removed the rib at the bottom of the cavity, remove the rib below. If you don't do this his empyema will not resolve completely. (2) Send pus for smear and culture, it may be tuberculous; tuberculous pus looks different, is more watery, contains particles and should not be drained anyway (see above and below).

Fix a wide tube in the empyema cavity, leaving about 2 cm above the skin surface. Fix it with a suture, a safety pin and adhesive strapping; apply a large gauze and cotton wool dressing.

POSTOPERATIVELY, encourage him to do vigorous breathing exercises. Monitor the size of the cavity by introducing contrast medium and taking X-rays. Alternatively, measure how much sterile saline you can run into it.

When drainage stops or becomes less than 5 ml/day, remove the tube. The residual sinus will heal, provided that there is no bronchopleural fistula. This can take 2 or 3 months.

Fig. 6-2 RESECTING A RIB. A, the patient's empyema covered with a thick layer of fibrous tissue. B, a common site for draining an empyema[md]his 9th rib in his paravertebral line. Vary this as the occasion demands. C, his skin incised, showing the incision over the periosteum. D, reflecting the periosteum with Faraboef's rougine. E, reflecting the periosteum off the inner surface of his rib. F, completing the task with Doyen's raspatory. G, resecting the rib. H, preparing to incise the periosteum in the bed of the rib. I, sucking out the pus. J, and K, putting in a finger to break down the loculi. L, a drainage tube in place.

CHILDREN [s7]WITH EMPYEMAS You cannot drain a small child's pleural cavity adequately by inserting an intercostal drain between two ribs, because the drain will be nipped by his ribs or obstructed by pus. So remove a centimetre or two of rib, using ketamine, to make a hole which is big enough for a tube. Adequate drainage will eventually cure him if: (1) his lung is not immobilized with thick fibrin, (2) he has no bronchopleural fistula, and (3) his empyema is localized.

Start drainage with an underwater seal drainage bottle. This will limit his activity, and may cause the drain to be pulled out; but his lung will expand. If necessary, drain the cavity with another high pleural drain as for a pneumothorax, see Fig. 65-2.

When you are confident that his lung has stuck to his ribs (see above), cut the tube short, fit it with a pin and butterfly strapping, put a colostomy bag over it to collect the pus and allow him up. Increased activity is the best physiotherapy. If he does not settle in 3 or 4 weeks, refer him.

DIFFICULTIES [s7]WITH AN EMPYEMA If his EMPYEMA PRESENTS ON HIS CHEST WALL (EMPYEMA NECESSITANS, unusual), it is almost sure to be tuberculous, perhaps a complication of AIDS. The signs suggestive of a tuberculous empyema are: (1) Swelling of the chest wall, starting first with swelling of its intercostal spaces. (2) Sinuses. (3) X-ray signs of pulmonary tuberculosis. (4) Typically, fluid on aspiration which is not pus, but is thin and watery with small particles of necrotic tissue. You may or may not find AAFB in the smear. Don't drain it or it will become secondarily infected. Give him chemotherapy for tuberculosis. If his mediastinum is shifted (unusual), aspirate some fluid.

If AIR COMES OUT WITH THE PUS, he has a BRONCHOPLEURAL FISTULA which is unlikely to close spontaneously. When his condition has improved, refer him to an expert thoracic surgeon, who will find the task of closing the fistula difficult.

If a patient with tuberculosis has an AIR-FLUID LEVEL IN A PLEURAL CAVITY, he has a TUBERCULOUS BRONCHOPLEURAL FISTULA. Give him chemotherapy (29.1). Using careful aseptic precautions, insert an underwater seal drain (65.2) and leave it in until his lung has expanded.

If his INTERCOSTAL VESSELS BLEED, encircle them with a needle and thread. Avoid tying the nerve because this is painful. If you have difficulty, transfix them with a ligature, so that they are compressed against the stump of the rib which remains.

If his EMPYEMA FAILS TO HEAL: (1) You may have put the drainage tube too high or too far forward. (2) You may have removed it too early. (3) You may have put it in too late. (4) There may be a foreign body, such as a piece of drainage tube, in his chest. (5) He may have developed a fistula between his bronchi and his pleura. (6) He may have tuberculosis, carcinoma, actinomycosis, or a ruptured amoebic liver abscess. Further dependent drainage is all that he probably needs for (1), (2) or (3). Instil 5 to 10 ml of contrast medium, repeat the X-ray, and if necessary resect another rib. If this fails, refer him.