Pneumonia: effusion, empyema
The presence, in association with pneumonia, of a small effusion that does not cause any respiratory distress can be managed conservatively without the need for aspirating a sample. A fluid sample, however, is needed if there is:
·a large effusion;
·no clear underlying diagnosis;
·persistent fever despite antibiotic treatment;
·long history (>14 days).
After US of the chest and checking blood-clotting studies, a small chest drain (or pigtail drain) should be inserted into the pleural fluid unless effu-sion is small. Samples should be sent for the following:
·Microbiology: bacterial culture and sensitivity, acidfast bacilli.
·Cytology: presence of pus cells and microscopic assessment of aberrant cell types. Cytology for lymphoma may give false –ve result in up to 10% of cases.
The diagnosis of empyema can be based on the presence of:
·Fluid: pH < 7.2, glucose <3.3mmol/L, protein >3g/L, pus cells.
· US scan: loculation or fibrin strands seen.
After inserting the small-bore drain or pigtail catheter, fluid should be allowed to drain into standard commercially available systems (e.g. water-seal two-bottle system). The drain can be removed if draining <50mL in 24hrs.
In empyema, as opposed to simple pleural effusion, instillation of uroki-nase via the chest drain is recommended.
·Dose: 40,000U urokinase in 40mL (10,000U in 10mL if <1yr) given 12-hourly for 3 days.
·Method: instil via the chest drain and then clamp the drain and encourage the patient to move and roll around over the next 4hr.
·Suction: use a low pressure suction device (e.g. Robert’s pump) to maintain suction of 20cmH2O between doses.
·Local anaesthetic: bupivacaine around the drain site may control pleural pain. Consult the pain control team.
If the effusion or empyema fails to resolve over a period of 7 days then a surgical opinion may be sought. Sometimes a chest CT scan is needed . A definitive surgical procedure or large bore drain and manual disruption of loculation may be needed.