A woman with acute dyspnoea

Answer

A pleuroperitoneal leak (fig 1).

Pleuroperitoneal leaks occur when there are congenital or acquired communications between the pleura and peritoneum (via the diaphragm). The raised intra-abdominal pressure with dialysate infusion promotes the translocation of dialysate into the pleural space in those with or at risk of developing diaphragmatic weakness.123

In this case it was assumed that a diaphragmatic defect was acquired through gradual weakening of the diaphragm muscle fibres, resulting from long term pressure exerted by instillations of peritoneal dialysate fluid; this occurs in approximately 1-2% of people undergoing peritoneal dialysis.23

Differential diagnoses of pleural effusion in a patient on peritoneal dialysis include a pleuroperitoneal leak, fluid overload, congestive heart failure, and other causes such as underlying malignancy or parapneumonic effusion, depending on clinical context.

However, a high glucose concentration in the transudative fluid (higher than the serum glucose level) is highly suggestive of a pleuroperitoneal leak.4

In more than half the cases there is a pre-existing diaphragm defect and pleuroperitoneal leaks develop in the first month after the initiation of peritoneal dialysis.3

Risk factors for developing diaphragmatic weakness after starting peritoneal dialysis include hiatus hernia, neuromuscular disease, and Guillain-Barré syndrome.

Diaphragmatic weakness is not routinely quantitatively evaluated in clinical practice; however, according to the literature it can be evaluated through ultrasonography and/or lung function tests.5 It is not typically evident on chest radiography.

Management usually involves switching to haemodialysis; drainage is not usually required. Surgical repair of diaphragmatic defects may be required if peritoneal dialysis is to continue.6