Thoracocentesis

Thoracocentesis for pleural effusion is usually done for diagnostic purposes. The actual tap can be done with a needle, venous cannula or trochar and catheter and, unless the chest radiograph shows a loculated effusion, it is done posteriorly over the seventh or eighth rib where the pleural space is

Right upper lobe

Right upper lobe

Figure 18.8. Radiographic appearance in lobar collapse.

deepest. The patient sits up and leans forward on a support and the procedure is done under a local anaesthetic. Fluid is sent for biochemistry, culture, cell count and cytology. Transudates have a low protein count and are likely to be due to cardiac failure, whilst exudates have a high protein count and are generally secondary to infection or malignancy. Large effusions are best managed by insertion of an intercostal catheter, which is preferably placed in the mid-axillary line at the sixth or seventh intercostal space as this is an area devoid of overlying muscles. The pleural space should be emptied completely but the drainage may need to be interrupted if the patient experiences chest pain as the lung re-expands. On rare occasions, re-expansion pulmonary oedema can occur if the effusion is drained too quickly.

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