Transfusion requirements during continuous veno-venous haemofiltration: the importance of filter life

Objective:To investigate the relationship between loss of haemofilter circu its due to blood clots and requirement for blood transfusion in intensive c are patients. Design: Retrospective case note review. Setting: A British, nine-bed, tertiary, medical and surgical intensive care unit (ICU) serving a 950-bed university teaching hospital. Patients: Thirty-three ICU patients requiring haemofiltration for more than 48 h. Thirty-three comparison patients requiring 7 or more days of intensi ve care, without haemofiltration. Methods: ICU, haemofiltration and haematology records were examined retrosp ectively. Note was taken of demographic data, daily haemoglobin concentrati ons and the dates and numbers of blood transfusions and haemofilter clots. Results: The study groups did not differ significantly in terms of age, sex and length of ICU stay. Haemo-filtered patients had higher APACHE II score s (21 vs 15, p = 0.006), lower haemoglobin concentrations (102 vs 110 g/l, p = 0.0001) and higher blood transfusion rates (1.1 vs 0.3 units/day, p < 0 .0001) when compared to the non-haemofiltered group. There was a positive c orrelation between haemofilter blood clot rate and blood transfusion rate ( r = 0.48). More blood was transfused on days when haemofilter blood clots o ccurred than on days when no haemofilter clot occurred (1.0 vs 0.59 units, p = 0.03). Conclusion: Haemofiltration is associated with an increased requirement for transfusion of blood. The temporal relationship between occurrence of haem ofilter blood clots and transfusion of blood suggests that haemofilter life span may be an important determinant of this.