Experience of Circuit Survival in Extracorporeal Continuous Renal Replacement Therapy Using Small-Calibre Venous Cannulae

To describe an experience of circuit survival in extracorporeal continuous renal replacement therapy using small-calibre (< 7 French gauge [F]) venous cannulae. An observational study. A multidisciplinary, university-affiliated PICU. Case note review of all continuous renal replacement therapy episodes (1998-2010), which used vascular access cannulae of an external diameter less than 7F, was performed. Forty-nine patients underwent continuous renal replacement therapy treatment during which circuit blood flow was delivered using either 5F or 6.5F double-lumen cannulae. One hundred thirty-nine circuits were employed (median per patient, 2; interquartile range, 1-3) in providing 4,903 hours of therapy (median duration of therapy, 43 hr; interquartile range, 22-86 hr); allowing for censoring, the median circuit survival time was 40 hours (95% CI, 28-66). Eighty-one circuits (58%) failed because of clotting/technical problems, equating to a circuit failure rate of 16.5 (95% CI, 13.3-20.5) per 1,000 hours of continuous renal replacement therapy. The probability of a circuit surviving 40 hours or greater was 50% with 43% (95% CI, 34-53%) expected to survive 60 hours or more. No significant relationship between circuit survival and the calibre of the cannula deployed was identified; however, placement of venous access in an internal jugular vein was associated with improved circuit survival. Contrary to previous reports, vascular access cannulae of a caliber less than 7F can support sufficiently prolonged continuous renal replacement therapy to make them a useful means of delivering renal support in neonates and small infants.