Undetected excessive ultrafiltration during maintenance haemodialysis.

Undetected excessive ultrafiltration (UF) occurred in 2 patients on maintenance haemodialysis (HD) using a Gambro AK-10 monitor and Ergo 120 A-G blood lines. In spite of alarms present on the monitor, the dialysis staff was not alerted to the faulty condition. Through investigation of the HD 'set-up' at the time of the incidents it was found that a partial obstruction (kinking) had occurred in the extracorporeal blood circuit where the flexible tubing joined the venous chamber. This created a very high positive pressure within the dialyzer compartment and excessive UF, which the blood circuit pressure monitoring transducer was unable to detect. To prevent kinking of the blood lines, dialysis staff and patients should be instructed to ensure that blood lines lie in smooth curves.