OBJECTIVE: To assess the effect on circuit life in continuous venovenous haemodiafiltration (CVVHD) by manipulating heparin dilution and point of administration. DESIGN: Repeated crossover design. Cases were randomised for first circuit and heparin dilution, after which crossovers occurred until treatment was stopped. SETTING: A 24-bed combined general and surgical intensive care unit admitting 1900 patients a year. On average, 54 cases a year receive CVVHD. PATIENTS: 26 critically ill adult patients requiring CVVHD were enrolled, 18 of whom used at least one standard circuit and one modified circuit. INTERVENTIONS: Two circuit configurations and heparin dilutions were compared. In combination A, standard CVVHD blood lines and heparin concentration (100 units/ml) were used. In combination B, heparin was delivered in a more dilute volume (10 units/ml) via a modified circuit design with an administration port immediately adjacent to the venous access. MEASUREMENTS AND RESULTS: 18 randomised crossovers of circuits A and B occurred. Mean/median circuit life for the standard heparin/circuit combination A was 20.1/17.5 (SD 14.6) and for the modified combination B 21.4/15.4 (SD 19.2). There was no significant difference between circuits (paired t-test, p = 0.8175). To identify other factors which could have influenced circuit life (platelet count, heparin dose and pre- and post-filter activated partial thromboplastin time, APTT) all circuits terminated for the reasons identified (n = 105) were analysed using linear modelling. Survival analysis was used to determine the survival function of the circuit. Pre-heparin APTT was the only factor associated with an increase in filter life (p = 0.035). The hazard rate for filter failure was 0.049/h (95% confidence interval 0.04 to 0.06), the range of time until filters failed was 1.8 to 78.5 h. CONCLUSIONS: Proximally administered dilute heparin is not associated with a significant increase in circuit life.
RCT Entities:
OBJECTIVE: To assess the effect on circuit life in continuous venovenous haemodiafiltration (CVVHD) by manipulating heparin dilution and point of administration. DESIGN: Repeated crossover design. Cases were randomised for first circuit and heparin dilution, after which crossovers occurred until treatment was stopped. SETTING: A 24-bed combined general and surgical intensive care unit admitting 1900 patients a year. On average, 54 cases a year receive CVVHD. PATIENTS: 26 critically ill adult patients requiring CVVHD were enrolled, 18 of whom used at least one standard circuit and one modified circuit. INTERVENTIONS: Two circuit configurations and heparin dilutions were compared. In combination A, standard CVVHD blood lines and heparin concentration (100 units/ml) were used. In combination B, heparin was delivered in a more dilute volume (10 units/ml) via a modified circuit design with an administration port immediately adjacent to the venous access. MEASUREMENTS AND RESULTS: 18 randomised crossovers of circuits A and B occurred. Mean/median circuit life for the standard heparin/circuit combination A was 20.1/17.5 (SD 14.6) and for the modified combination B 21.4/15.4 (SD 19.2). There was no significant difference between circuits (paired t-test, p = 0.8175). To identify other factors which could have influenced circuit life (platelet count, heparin dose and pre- and post-filter activated partial thromboplastin time, APTT) all circuits terminated for the reasons identified (n = 105) were analysed using linear modelling. Survival analysis was used to determine the survival function of the circuit. Pre-heparin APTT was the only factor associated with an increase in filter life (p = 0.035). The hazard rate for filter failure was 0.049/h (95% confidence interval 0.04 to 0.06), the range of time until filters failed was 1.8 to 78.5 h. CONCLUSIONS: Proximally administered dilute heparin is not associated with a significant increase in circuit life.
Authors: P Y Tam; S Huraib; B Mahan; D LeBlanc; C A Lunski; C Holtzer; C E Doyle; S I Vas; P R Uldall Journal: Clin Nephrol Date: 1988-08 Impact factor: 0.975