CONTINUOUS ARTERIOVENOSUS HEMODIAFILTRATI ON AND EARLY OBSTRUCTION OFTHE FILTER

During the use of continuous hemofiltration as an extracorporeal techn ique of blood purification an early obstruction of the filter, defined as a reduction in ultrafiltration rate below 250 ml/hour during the f irst functioning 22 hours of the filter, is occasionally seen. If anti coagulation is adequate and no hemodynamic and mechanical factors exis t, no apparent cause is found to explain the filter obstruction. The a im of this study was to determine the causes of this early filter obst ruction. We studied 12 patients with multiple organ failure and acut'e renal failure on continuous arteriovenosus hemodiafiltration. Eighty one filters were studied in two groups: those with early obstruction o f the filters (n = 38) and those withadequate function for more than 2 2 hours (n = 43). Blood coagulation parameters and parameters determin ing the ultrafiltration rate were compared between the two groups. We did not find any disorder of coagulation, including AT III levels, or factors determining the ultrafiltration rate, which could explain the early obstruction of some filters. Hemodynamic factors (hypotension) a nd mechanical factors (bend in tubing, etc.) were excluded. The early obstruction of the filters implies an elevated economic cost and an in creased workload for nurses.