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What is the mechanism underlying the development of transudative pleural effusions? Name some causes of transudative pleural effusion.

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Transudative effusions arise from alterations in hydrostatic and oncotic pressure that result in a rate of pleural fluid formation that exceeds its resorption. Congestive heart failure is the most common cause of transudative effusion. Other causes of transudative effusion include hepatic failure (ascites) and nephrotic syndrome.

What are the criteria for differentiating transudative and exudative pleural effusions?

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The criteria for differentiating transudative and exudative pleural effusions are Light's criteria. Light's criteria are: Pleural fluid protein greater than 0.5 x serum protein, Pleural fluid LDH greater than 0.6 x serum LDH, Pleural fluid LDH greater than 2/3 of upper-limit of serum LDH. A pleural effusion is exudative if at least one of these criteria are met.

This patient experienced a small, iatrogenic pneumothorax without haemodynamic instability or associated symptoms. Are there any treatments could be considered to aid in the resolution of the patient's pneumothorax?

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Supplemental oxygen could be considered, which works to address hypoxaemia (if present) and promote absorption of air from the pleural space (4). Positive pressure ventilation (including use of high-flow nasal cannulae) should be avoided, as this can worsen the pneumothorax and perpetuate the air leak.