The effect of a nylon mesh blood filter in the arterial line during extracorporeal circulation

Forty patients with different cardiac diseases underwent perfusion with the Shiley bubble oxygenator without a filter in the arterial line (Group A). This group was compared with a similar group of patients (Group B), in whom an Intersept nylon mesh filter was used in the arterial line. There were no differences according to age, weight or duration of perfusion between the two groups. The average postoperative bleeding via the chest tubes was 361 ml/m2 B.S.A./24 hours in group A compared with 414 in group B (p less than 0.05). One patient in the filter group died on the table because of myocardial failure, while the remaining 79 patients could leave hospital alive. One patient in each group showed impaired consciousness, but no other neurological complications were recorded in the patients. There were no significant differences in haematocrit, B-haemoglobin or leucocyte counts after 15 min, 1 hour, at the end of perfusion or 1 hour, respectively 24 hours postoperatively. The platelet count after 1 hour of perfusion was 55.8 x 10(9)/l in the filter group compared with 80.4 x 10(9)/l in group A (p less than 0.05), there were, however, no significant differences in B-platelet counts at the end of perfusion or later. Our study showed that a nylon mesh filter in the arterial line can reduce the platelet count. As no measureable advantages were found in the filter group we cannot recommend an arterial line filter.