Positive pressure-assisted pleural aspiration: A case report of a novel procedure and a review of literature

Drainage of a pleural effusion is done either by inserting an intercostal tube or by aspirating pleural fluid using a syringe. The latter is a time-consuming and labour-intensive procedure. The serious complications of pleural aspiration are the development of a pneumothorax and re-expansion pulmonary oedema. We describe an observation made during a pleural aspiration in a patient who was on positive pressure ventilation. We explain the physiological basis for the observation, the safety of the procedure and its potential to reduce complications by reviewing the literature. A 56-year-old Sri Lankan female patient with end-stage kidney disease presented with fluid overload and bilateral pleural effusions. She was found to have concurrent COVID pneumonia. The patient was on bilevel positive airway pressure, non-invasive ventilation when pleural aspiration was done. The pleural fluid drained completely without the need for aspiration, once the cannula was inserted into the pleural space. One litre of fluid drained in 15 min without the patient developing symptoms or complications. Positive pressure ventilation leads to a supra-atmospheric (positive) pressure in the pleural cavity. This leads to a persistent positive pressure gradient throughout the procedure, leading to complete drainage of pleural fluid. Pleural fluid drainage in mechanically ventilated patients has been proven to be safe, implying the safety of positive pressure ventilation in pleural fluid aspiration and drainage. It further has the potential to reduce the incidence of post-aspiration pneumothorax by reducing the pressure fluctuations at the visceral pleura. Re-expansion pulmonary oedema is associated with a higher negative pleural pressure during aspiration, and the use of positive pressure ventilation can theoretically prevent re-expansion pulmonary oedema. Positive pressure ventilation can reduce the re-accumulation of the effusion as well. We suggest utilizing positive pressure ventilation to assist pleural aspiration in suitable patients.