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Background and Aims: Continuous veno-venous haemofiltration (CVVH) is an established treatment for acute renal failure (ARF). Recently, extended intermittent dialytic techniques have been proposed for the treatment of ARF. The aim of this study was to compare these two approaches.Setting: Intensive care unit of tertiary hospital.Subjects: Sixteen critically ill patients with ARF.Design: Randomised controlled trial.Intervention: We randomised sixteen patients to three consecutive days of treatment with either CVVH (8) or extended daily dialysis with filtration (EDDf) (8) and compared small-solute, electrolyte and acid-base control.Results: There was no significant difference between the two therapies for urea or creatinine levels over 3 days. Of 80 electrolyte measurements taken before treatment, 19 were abnormal. All values were corrected as a result of treatment, except for one patient in the CVVH group who developed hypophosphataemia (0.54 mmol/l) at 72 h. After 3 days of treatment, there was a mild but persistent metabolic acidosis in the EDDf group compared to the CVVH group (median bicarbonate: 20 mmol/l vs. 29 mmol/l: p=0.039; median base deficit: -4 mEq/l vs. -2.1 mEq/l, p=0.033).Conclusions: CVVH and EDDf as prescribed achieved similar control of urea, creatinine and electrolytes. Acidosis was better controlled with CVVH. [ABSTRACT FROM AUTHOR]

Objective: Reductions in blood flow rate may occur undetected during peristaltic pumping of blood through continuous renal replacement therapy circuits. We investigated whether undetected reductions in blood flow rate occur during continuous veno-venous haemofiltration, and whether they are correlated with filter life.Patients: Twelve patients receiving continuous veno-venous haemofiltration in the intensive care unit of a tertiary hospital.Methods: Extracorporeal circuit blood flow during haemofiltration was continuously monitored utilizing a miniature ultrasound Doppler device. Otherwise undetected blood flow reductions were identified at severity levels of between 20% and 100% less than the set diastolic flow rate (83 ml/min). Information on anticoagulation status was simultaneously obtained. The frequency and severity of blood flow reductions were recorded, and the correlation with filter life was determined.Measurements and Results: The duration of filter life ranged from 1.5 to 53 h, with a mean functional life of 19.62+/-16.32 h. There were 314 episodes of blood flow reduction during the 525 h of monitoring (0.59 episodes/h). There was a significant inverse relationship between the number of medium-level blood flow reductions and filter life. This correlation was much stronger than that between APTT and filter life.Conclusions: Undetected blood flow reductions occur during continuous veno-venous haemofiltration. Such reductions are frequent, and when sufficiently severe appear to be correlated with filter life more strongly than the blood coagulation variables typically used to monitor adequacy of anticoagulation and promote filter longevity. [ABSTRACT FROM AUTHOR]

Objective. To establish a technique for the monitoring and graphic display of blood flow during continuous renal replacement therapy (CRRT). Design and setting. Technique assessment study in a tertiary intensive care unit. Patients. Six ICU patients receiving CRRT. Interventions. A technique was devised to monitor and graphically display blood flow during CRRT. This technique used a mini-ultrasound Doppler probe attached to the blood tubing with link to a lap top computer for quantitative graphic display. Blood flow was measured and displayed during routine treatment using this method in six patients. Measurements and results. Blood flow wave data were monitored and successfully displayed as a real-time wave form and analysed using Windaq data analysis software. This initial analysis over a 6-h period revealed the following facts: (a) blood flow was not the same as set by the machine roller pump on nine occasions, (b) blood flow reductions defined as a drop in the 'diastolic' were 20% (seven) and 30% (two) less than set flow, (c) flow reductions frequently failed to trigger machine alarms, and (d) the blood flow wave displayed had unique characteristics. Complete flow monitoring was then undertaken for the functional life of one haemofilter over 24.5 h. There were 27 blood flow reductions, and blood flow was less than set for a total of 463.9 min or 31.5% of operating time. Conclusions. Blood flow during CRRT can be monitored by an ultrasound Doppler probe and displayed graphically. Preliminary data using this technique suggest potentially serious and undetected problems with blood flow during routine CRRT. [ABSTRACT FROM AUTHOR]