Paediatrics: Pneumonia (effusion, empyema)

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;
• respiratory distress;
• persistent fever despite antibiotic treatment;
• long history (>14 days).

Fluid sample

After the US of the chest and checking blood-clotting studies, a small chest drain (or pigtail drain) should be inserted into the pleural fluid unless effusion is small. Samples should be sent for the following:

• Microbiology: bacterial culture and sensitivity, acid-fast bacilli.
• Cytology: the presence of pus cells and microscopic assessment of aberrant cell types. Cytology for lymphoma may give false results in up to 10% of cases.

Diagnosis of empyema

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 are seen.

Fluid drainage

After inserting the small-bore drain or pigtail catheter, the 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.

Urokinase for empyema

In empyema, as opposed to simple pleural effusion, instillation of urokinase via the chest drain is recommended.

• Dose: 40,000U urokinase in 40mL (10,000U in 10mL if <1yr) given12-hourly for 3 days.
• Method: instill 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 anesthetic: bupivacaine around the drain site may control pleural pain. Consult the pain control team.

Surgical referral

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.