Correction of discrepancy between prescribed and actual blood flow rates in chronic hemodialysis patients with use of larger gauge needles.
Academic Article
Overview
abstract
The blood flow rate delivered by the dialysis machine (d-BFR) may not be accurately reflected by the blood flow rate set on the machine (sm-BFR). High negative arterial pressure may lead to deformity of the blood pump-segment tubing, resulting in a lower stroke volume and d-BFR. The Hagen-Poiseuille law predicts that the use of larger gauge needles should make arterial pressure less negative. Twenty-two patients on chronic hemodialysis therapy with a percentage of reduction in urea (PRU) levels less than 65% and/or a greater than 10% difference between sm-BFR and d-BFR underwent dialysis using one-gauge larger arterial and venous needles. d-BFR increased by 23 +/- 5 mL/min. Arterial pressure became less negative by 58 +/- 5 mmHg, and venous pressure decreased by 31 +/- 7 mm Hg. Changes in arterial and venous pressures allowed sm-BFR to be increased to 500 mL/min in all 22 patients, resulting in an increase in d-BFR of 83 +/- 7 mL/min. This translated into an increase in PRU of 5% +/- 0.01%. All results were significant at P < 0.001. A survey showed that less than 5% of needles used in our region were 14 G. This study shows that the use of larger gauge needles can significantly increase d-BFR and PRU as a result of changes in arterial and venous pressures, resulting in a significantly increased dialysis dose at no additional cost.
