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Access type as a predictor of dialysis adequacy in chronic hemodialysis patients
1Department of Medicine, London Health Sciences Center, Ontario, Canada.
Insights
Vascular access type did not significantly impact the difference between prescribed and delivered dialysis doses. However, patients with tunneled catheters received shorter dialysis sessions, suggesting potential physician bias. Adequate dialysis is achievable regardless of access method.
Area of Science:
- Nephrology
- Vascular Surgery
- Internal Medicine
Background:
- Dialysis prescription often exceeds delivered dose.
- Tunneled catheters may yield less dialysis than AVF or grafts.
- Impact of access type on dialysis dose discrepancy is unknown.
Purpose of the Study:
- Investigate the relationship between vascular access type and dialysis dose discrepancy (deltaHD).
- Compare delivered vs. prescribed Kt/V(urea) across different access modalities.
Main Methods:
- Prospective study of 53 chronic hemodialysis patients over 3 weeks.
- Measured delivered and prescribed single-pool Kt/V(urea).
- Categorized patients by vascular access: arteriovenous fistula (AVF), graft (GG), or tunneled catheter (PC).
Main Results:
- No significant difference in deltaHD across AVF, GG, and PC groups.
- Prescription times were shorter for PC patients compared to AVF and GG.
- 86.7% of all patients achieved Kt/V(urea) > 1.3, with no significant difference by access type.
Conclusions:
- Vascular access type is not a significant predictor of dialysis dose discrepancy.
- Physician bias may lead to shorter dialysis prescriptions for patients with tunneled catheters.
- Adequate dialysis delivery is feasible even with tunneled catheters.
Abstract:
Dialysis prescription commonly exceeds the delivered dialysis dose. Tunneled hemodialysis catheters (PC) may provide less dialysis than arteriovenous fistula (AVF) and polytetrafluoroethylene grafts (GG), but the impact of access type on the discrepancy (deltaHD) between dialysis prescription and dose is unknown. This study investigates the relationship between deltaHD and vascular access type. Fifty three chronic hemodialysis patients in our unit were prospectively studied for 3 weeks with measurement of delivered single pool and prescribed Kt/V(urea). There were 25 patients with AVF, 17 with GG, and 11 with PC. Demographic characteristics did not significantly differ between groups. Mean prescribed Kt/V(urea) was 1.73 +/- 0.26, and mean delivered Kt/V(urea) was 1.61 +/- 0.26. For 10 of 53 (19%) patients, dialysis delivery was at least equal to that prescribed, and this proportion did not differ between access types. Forty six of fifty three patients (86.7% of all patients) received Kt/V(urea) > 1.3, with no difference in this proportion between access types: AVF 22 of 25 (88.0%), GG 16 of 17 (94.1%), PC 8 of 11 (72.7%). Surprisingly, prescription times for patients with PC (3.6 +/- 0.3 hr) were significantly shorter than for those with AVF (3.9 +/- 0.3 hr) and GG (3.9 +/- 0.3 hr) (p = 0.02), perhaps indicating physician bias toward patients with tunneled catheters. In summary, access type was not a significant predictor of deltaHD, although patients with arteriovenous access tended to receive more dialysis than those with tunneled catheters. While a large proportion of patients received less dialysis than prescribed, the high levels of delivered Kt/V(urea) indicate that adequate dialysis is possible even in patients who must use tunneled catheters.