Needle Direction and Distance of Arteriovenous Fistula Cannulation in Hemodialysis Adequacy; a Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to summarize the evidence regarding the impact of nee-dle direction and distance of arteriovenous fistula (AVF) cannulation on KT/V (where k is the dialyzer urea clearance, t,the duration of dialysis, and V, the volume of distribution of urea) and access recirculation (AR) as hemodialysis (HD) ad-equacy criteria.

A comprehensive systematic search was performed on international and domestic electronicdatabases from the earliest to June 4, 2022 using keywords. Analysis was performed in STATA software v.14.

Three randomized control trials (RCTs) and four non-RCT articles were included in the final review. Six studies reportedthe effects of direction, while four mentioned the effects of distances of AVF cannulation on outcomes of HD adequacybased on KT/V or AR. Results of three non-RCT studies showed that retrograde direction decreased KT/V more than an-tegrade direction (ES: 0.44, 95% CI: -0.38 to 1.27). Two non-RCT studies showed that antegrade decreased AR comparedto the retrograde direction (ES: -0.64, 95%CI: -1.94 to 0.67). However, the results of two RCTs indicated uncertainty aboutthis issue. Two of the four studies suggested that a distance of 5 cm or more in arterial and venous needles had greateradequacy than a distance of less than 5 cm. However, other studies did not confirm this finding.

Overallcomparison of the results qualitatively and quantitatively indicated uncertainty about the effects of direction and dis-tance of AVF cannulation on HD adequacy outcomes. More studies with high-quality designs, such as RCTs, are requiredto better understand and adjudicate the effects of needle direction and distance of AVF cannulation on HD adequacyoutcomes.