[Is there an indication for the use of "micropore-blood filters"? (AUTHOR'S TRANSL)]

Recently "micropore" blood transfusion sets have been advocated to replace the traditional transfusion sets. Because of the higher cost it is important to review critically the data which would justify their clinical use. The filters eliminate microaggregates as they occur during blood storage. The question is wether micropore filters are able to reduce the incidence of posttraumatic or postoperative respiratory insufficiency. We have analysed all controlled in vivo studies. We found only one clinical study where in massively transfused polytrauma patients a decrease in the number of cases of respiratory insufficiency was documented. However, due to the small number of patients investigated, a significant difference in favour of the micropore filters could not be demonstrated. Animal experiments reveal more: Exchange transfusions carried out in dogs through micropore filters do not lead to functional or morphological pulmonary changes. Using traditional transfusion sets, a significant increase in pulmonary artery pressure and resistance was found together with a decrease in arterial pO2, pH and oxygen consumption. All these results correlate well with morphological changes in the lung. On the basis of our literature review, we conclude that there are no clear data which would make it mandatory to use micropore filters in clinical practice. On the other hand, there are several indirect hints than large amounts of microaggregates are not ideal for pulmonary function. The expensive micropore filters could therefore perhaps be used with advantage in massive tranfusions.