How continuous is continuous veno-venous haemofiltration?
© BioMed Central Ltd 2006
Published: 21 March 2006
Data exist from centres in the United States and Australia demonstrating that only 67–85% of the planned cycle time of CVVH could be delivered due to unplanned interruptions. As there is some evidence that higher CVVH doses may improve outcome, interruptions may adversely affect the outcome of critically ill patients with acute renal failure.
We undertook an audit of CVVH in two tertiary adult ICUs (total of 15 beds) in the United Kingdom. Patients requiring CVVH were audited, and data on length and causes of any interruptions were collected.
% of lost time
Air in circuit
This audit demonstrates that filter clotting is by far the most common cause for interruption of CVVH and is responsible for 70.7% of lost CVVH time. Planned interruptions represent a small minority (10%). The total time lost from CVVH was only 7.7%, considerably less than previously reported. This may well be due to the closed organisation of our units and increased awareness of the important role of CVVH among staff. However, time lost from CVVH varied widely (0–34%) and one patient illustrates the persisting problem: repeated prescription of an erroneously low CVVH dose of 28 ml/kg/hour (instead of 35 ml/kg/hour) and multiple unplanned interruptions led to an average dose of only 18 ml/kg/hour, approximately one-half of the intended dose.
Multiple unplanned interruptions occur frequently during CVVH treatment in intensive care and can have considerable negative impact on the total delivered dose of CVVH.