The low-flow method has been shown as a reliable evaluation of access
recirculation. Few data is available on temporary central catheter blo
od recirculation; results of 2% and 4% have been reported in subclavia
n, 10% in 24 cm long femoral, and 18% in 15 cm long femoral catheters,
mostly in indwelling catheters for chronic hemodialysis. The purpose
of this prospective study was to evaluate blood recirculation in a lar
ger number of recently inserted temporary intravenous catheters for ac
ute hemodialysis, comparing subclavian and femoral sites. Fifty blood
recirculation measurements were performed in 38 different temporary ce
ntral venous dialysis catheters inserted in thirty-one critically ill
patients from medical and surgical intensive care units presenting acu
te renal failure supported by intermittent hemodialysis. All the cathe
ters used were well-functioning 11.5 French dual lumen Quinton of 13.5
or 19.5 cm length. Catheters presenting mechanical dysfunction, which
did not allow a blood flow rate of 300 ml/min or for which lines had
to be reversed were excluded from the analysis. Access blood recircula
tion was measured shortly after catheter insertion according to the lo
w flow method applied after the first 30 minutes of hemodialysis at a
blood flow rate of 300 ml/min. Mean blood recirculation for the 50 mea
surements was 10.3 +/- 9.2%. It was significantly higher in the 26 fem
oral catheters than in the 24 subclavian catheters, reaching respectiv
e means of 16.1 +/- 9.1% and 4.1 +/- 3.6% (p = 0.0001). Blood recircul
ation rate was not different between 13.5 cm and 19.5 cm long subclavi
an catheters (3.0 +/- 2.6%, n = 13, versus 5.4 +/- 4.3%, n = 11, respe
ctively), but was significantly higher in 13.5 cm than in 19.5 cm long
femoral catheters (22.8 +/- 9.1%, n = 9, versus 12.6 +/- 6.9%, n = 17
) (p = 0.004). Blood recirculation was measured on two separate occasi
ons in 12 catheters randomly selected (5 femoral and 7 subclavian cath
eters); the obtained results were reproducible with a mean difference
of only 2.1 +/- 1.8% between the two measurements and a correlation of
0.96. The mean time elapsed between catheter insertion and recirculat
ion assessment was 2.2 +/- 3.1 days and was similar for femoral and su
bclavian catheters. No correlation was found between the percentage of
recirculation and the arterial and venous resistances recorded during
dialysis session or with the time from catheter insertion. Mean urea
reduction ratio (URR) for the 50 dialysis sessions was 57.8 +/- 13.0%.
It was significantly higher for sessions performed with subclavian th
an with femoral catheters (62.5 +/- 10.9%, n = 24, versus 54.5 +/- 14.
2%, n = 26) (p = 0.03). In conclusion, the expected blood recirculatio
n in well-functioning and recently inserted temporary dialysis cathete
rs is under 5% for subclavian, over 12% in 19.5 cm femoral, and over 2
2% in shorter 13.5 cm femoral catheters at a blood flow rate of 300 ml
/min. The consequently reduced dialysis efficiency with femoral cathet
ers is another factor to be considered in the choice of a site for tem
porary dialysis catheter insertion in acute renal failure patients, pa
rticularly when dialysis dose delivery is a priority, such as intoxica
tion cases treated by extracorporeal therapy.