Blood--dialyzer interactions: hemodynamic manifestations in an animal model

A sheep model is described that reliably produces acute pulmonary hypertension after blood, previously in contact with a number of different dialysis membranes including Cuprophan, enters the animal's circulation. This hemodynamic manifestation is associated with myocardial ischemia and arrhythmias and coincides in time with neutropenia but precedes maximal hypoxemia. The resulting pulmonary vascular response occurs following both exposure of flowing blood to a dialyzer in an extracorporeal circuit and reinjection of blood previously in static contact with a number of different devices for varying periods of time. Increasing volumes (1-15 ml) previously in static contact (10 min) with regenerated cellulose, saponified cellulose ester, and Cuprophan (hollow fiber and sheet form) caused varying increments in mean pulmonary artery pressure. Contact with either polyacrylonitrile or cellulose acetate resulted in little response. This effect was magnified with all the surfaces, even polyacrylonitrile and cellulose acetate, by prolonging the duration of contact up to 30 min. The hemodynamic events that occurred with this model are similar to those reported in the clinical entity of "dialyzer hypersensitivity." This model may be of value in the quest for elucidation of the mechanisms involved in this syndrome.