Clinical disorders of lung liquid.

Clinical pulmonary oedema is often persistent and of sudden onset, suggesting a vicious circle, i.e. positive feedback. It is difficult to produce in animals by any haemodynamic manoeuvres, but the important neurogenic component can be illustrated by acutely increasing cerebrospinal fluid pressure of rabbits to 300 mmHg (40 kPa). Breathing stops virtually at once, and restarts when cerebrospinal fluid pressure is again reduced. With cerebral ischaemia lasting for up to 2 min, all is well; with longer times pulmonary oedema is almost invariable and often eventually fatal, although the animals may otherwise apparently recover. Comparable events sometimes follow subarachnoid haemorrhage in man. A few hypotheses on the pathogenesis of pulmonary oedema in man are offered.