title: [Recirculation of urea and dialysis efficiency using dual-lumen dialysis catheters in various locations: may the venous lumen of the catheter be used as the arterial lumen and vice versa?].
abstract: OBJECTIVE
  To measure percentage of urea recirculation in hemodialysis by a dual-lumen central venous catheters of various localisations (e.g. jugular, subclavian and femoral), and also in cases when the venous lumen of the catheter is used as arterial lumen, and vice versa, and under these conditions to evaluate the efficiency of hemodialysis based on the measurements of urea reduction ratio.
  
  
  METHODS
  Percentage of urea recirculation was measured in the patients with acute and chronic renal failure who underwent hemodialysis by a temporary dual-lumen central venous catheter of different localisations (jugular n = 16, subclavian n = 20, femoral n = 20). The measurements were done in cases when arterial line was connected to arterial lumen of the catheter, and venous line to the venous lumen of the catheter (correct connection = RI), and vice versa, i.e., when arterial line was connected to venous lumen of the catheter, and venous line was connected to arterial lumen of the catheter (reversed connection = R2). The efficiency of hemodialysis was evaluated by measuring urea reduction ratio in cases with the reversed (R2) connection.
  
  
  RESULTS
  Statistically significant differences were found between R1 and R2 for jugular catheters (R1 = 2.38 +/- 1.09%, R2 = 7.59 +/- 1.42%, n = 16, p = 0), for subclavian catheters (R1 = 3.03 +/- 3.15%, R2 = 15.8 +/- 7.18, n = 20, p = 0), and for femoral catheters (R1 = 9 +/- 6.56%, R2 = 29.2 +/- 11.8%, n = 20, p = 0). Statistically significant differences were also found between R1 of jugular catheters and R1 of subclavian catheters (2.38 +/- 1.09%, n = 16 and 3.03 +/- 3.15%, n = 20, p = 0.0001), further on between R1 of jugular and R1 of femoral catheters (2.38 +/- 1.09%, n = 16 and 9 +/- 6.56%, n = 20, p = 0), as well as between R1 of subclavian and R1 of femoral catheters (2.38 +/- 1.09%, n = 20 and 9 +/- 6.56%, n = 20, p = 0.0001). Also statistically significant differences were found between R2 of jugular and subclavian catheters (7.59 +/- 1.42%, n = 16 and 15.8 +/- 7.18%, n = 20, p = 0.0003), between R2 of jugular and femoral catheters (7.59 +/- 1.42%, n = 16 and 29.2 +/- 11.8%, n = 20, p = 0.0007), and between R2 of subclavian and R2 of femoral catheters (15.8 +/- 7.18%, n = 20 and 29.2 +/- 11.8%, n = 20, p = 0.0029). The measurements of urea reduction ratio that we have done for some of the catheters under R2 conditions showed a statistically significant difference between femoral and subclavian catheters (51.45 +/- 5.62%, n = 20 and 63.75 +/- 7.61, n = 20, p = 0), and between femoral and jugular catheters (51.45 +/- 5.62%, n = 20 and 64.3 +/- 5.23%, n = 16, p = 0). No statistical differences were found in urea reduction ratio between jugular and subclavian catheters (64.3 +/- 5.23, n = 16 and 63.75 +/- 7.61%, n = 20, p = 0.8).
  
  
  CONCLUSIONS
  When hemodialysis is delivered by a correct blood lines connection the measurements have shown a decrease in urea recirculation by 5% for jugular and subclavian catheters, and 5%-10% for femoral catheters. However, in cases when the venous lumen of the catheter is used as an arterial lumen, and vice versa, urea recirculation is below 10% for jugular catheters; whereas in femoral catheters the percentage is higher than 20%. Despite so high percentage of urea recirculation, that we obtained for such use of the catheters, urea reduction ratio in hemodialysis via jugular and subclavian catheters is > 60%, whereas via femoral catheters, the percentage is significantly lower. Consequently, the efficiency of hemodialysis is reduced, and such use of femoral catheters should therefore be avoided.
authors.affiliation: KB Sestre milosrdnice, Zavod za nefrologiju i dijalizu, Vinogradska c. 29, 10 000 Zagreb.
authors.forename: Sinisa
authors.initials: S
authors.lastname: Sefer
authors.forename: Petar
authors.initials: P
authors.lastname: Kes
authors.forename: Vesna
authors.initials: V
authors.lastname: Degoricija
authors.forename: Branko
authors.initials: B
authors.lastname: Heinrich
authors.forename: Mislav
authors.initials: M
authors.lastname: Vrsalović
mesh_terms: D002404:Catheterization; D002405:Catheterization, Central Venous / Q000295:instrumentation*; D005268:Femoral Vein; D006801:Humans; D007601:Jugular Veins; D006435:Renal Dialysis / Q000295:instrumentation* / Q000379:methods; D013350:Subclavian Vein; D014508:Urea / Q000097:blood*
chemical_list: D014508:Urea