Ventilatory failure in shrinking lung syndrome is associated with reduced chest compliance.

Shrinking lung syndrome is an extremely rare feature of systemic lupus erythematosus (SLE). We report on a 49-year-old woman with SLE who presented with dyspnoea in type 2 respiratory failure requiring mechanical ventilation. Medical imaging investigations revealed markedly reduced lung volumes and the absence of pulmonary emboli, pulmonary fibrosis or any significant parenchymal infiltrate consistent with shrinking lung syndrome. We observed significantly reduced chest compliance during positive pressure ventilation and noted that this contrasts with a widely held view that diaphragmatic weakness is the major pathophysiological mechanism for ventilatory failure in these patients. She was treated with high-dose steroids and cyclophosphamide and weaned slowly off full mechanical ventilation. This report highlights an unusual cause of respiratory failure in a patient with SLE and provides support for reduced chest compliance rather than the diaphragmatic weakness as being the significant pathophysiological mechanism for ventilatory failure in these patients.