Dialysis is a simple diffusion of molecules in a solution through a semipermeable membrane along an electrochemical concentration gradient, which leads to the aim of hemodialysis being a restoration of intracellular and extracellular fluid environment similar to the normal renal (kidney) function. Hemodialysis (HD) is required by the patients having Chronic Renal Failure (CRF) to remove toxins and additional body fluid from the blood. To do so, an Arteriovenous Fistula (AVF) is placed in the upper limb to grant vascular or precisely Arteriovenous Access (AVA) for hemodialysis.
Similarly, an Arteriovenous Graft (AVG) can also be used to develop a conduit between artery and vein for performing dialysis. The thrill of the AVA is significant for assessing the normal function of graft during HD, weak thrill refers to arterial stenosis, with poor arterial blood flow, while feeling a pulse indicates intense stenosis at the outflow of AVA. Likewise, high venous blood pressure may refer to stenosis at the venous outflow. The condition of AVF is imperative, as infections in it can pose risks of infection, sepsis, ischemic heart disease, and mortality. A fistula must withstand the supply and demand for the hemodialysis machine, for which the blood flow rate through the fistula should be higher than the requirement of a blood pump. To measure the Blood Flow Rate (BFR) the most effective and non-invasive method used is Duplex Ultrasound.
Since BFR is an important element for the success of HD, and there isn’t much evidence available on the relationship of lower BFR with the success of HD, a prospective cohort of 44 patient was conducted at King Fahad Hospital in KSA to fill this research gap, which concluded that patients with BFR<500 mL min–1 have acceptable HD success rate than in the patients with BFR> 500 mL min-1. Creatinine clearanceby kidneysand Serum phosphate are two important indicators for accessing renal function. To access the effectiveness of HD factors like BFR, Dialysis Fluid Flow Rate (DFR), and mass transfer area coefficient are observed.
This 6-month long study enrolled CRF patients that underwent HD, Duplex Ultrasound (DUS) was used to assess AVF and to calculate BFR. The results showed that the success rate of patients with BFR of 400-500 mL min-1 isn’t much different from the patients with BFR>500 mL min-1. Another interesting observation was that the AVF of small diameter (radio-cephalic) and larger diameter (brachiocephalic) both shown a good degree of success despite their different blood flow rates. They also observed that high BFR was accompanied by symptoms like heart failure due to High Cardiac Output Failure.
The study concluded that the use of radio-cephalic AVF is better than basilic (or brachiocephalic) AVF as they show lower BFR and pose low risks of high cardiac output failure. These findings will help the physicians in taking better care of chronic renal failure patients, who are on HD. In the future, more studies should be done on a similar objective with greater sample size, and prolong laboratory assessment should be done.
Hemodialysis, peritoneal dialysis, Arteriovenous Fistula (AVF), Blood Flow Rate (BFR), Chronic Renal Failure (CRF), success rate, Arteriovenous Graft (AVG)