Relationship between Blood Flow in Central Venous Catheters and Hemodialysis Adequacy

Abstract

Central venous catheter dysfunction is a frequent problem and often is defined as a blood flow <300 ml/min. This prospective, cross-sectional study included 259 patients and examined the relationship between catheter blood flow and dialysis adequacy as measured by urea reduction ratio (URR), single pool urea kinetics, and online effective ionic dialysance clearance. Dialysis adequacy at blood flow rates of <300, <275, and <250 ml/min; sensitivity; specificity; and positive and negative predictive values were calculated. Mean blood flow was 352 ml/min (SD ؎ 48.8). Mean blood flow <300 ml/min occurred in 10.5% of the patients, and only 26% had a URR of <65%. Maximum blood flows <300 ml/min occurred in 6.9% of patients, and only 22.2% had URR <65%. The positive predictive value of mean blood flow of <300 and <275 ml/min to predict a URR <65% was 22 and 40%, respectively. Using receiver operator characteristic curves, the area under the curve was not significantly different for blood flows of 300, 275, or 250 ml/min. This study indicates that mean blood flows <300 ml/min are not commonly associated with dialysis inadequacy. Setting a single blood flow cut point of <300 ml/min to define the need for intervention will result in a significant number of unnecessary interventions. There is a need to reexamine the definition of catheter dysfunction and expand the definition beyond blood flow rates.Clin C uffed, tunneled, dual-lumen central venous catheters (CVC) have become an acceptable form of hemodialysis (HD) vascular access when other permanent vascular accesses are unavailable, despite the associated high complication rates and mortality risk (1-4). In Canada, up to 70% of patients initiate HD with a CVC, and 33% continue to use catheters 90 days after dialysis initiation (5). This is far in excess of the National Kidney Foundation-Dialysis Outcomes Quality Initiative (NKF-DOQI) recommendation that CVC be used in Ͻ10% of prevalent HD patients (6).A common complication of the CVC is its inability to deliver adequate dialysis as a result of dysfunction. The definition of CVC dysfunction varies across the literature and includes variable rates of blood flow ranging from Ͻ100 to 350 ml/min (7-16). The NKF-DOQI vascular access guideline defines CVC dysfunction as failure to attain and maintain extracorporeal blood flow that is sufficient to perform HD without significantly lengthening the HD treatment and considered insufficient extracorporeal blood flow to be Ͻ300 ml/min (6). This recommendation was opinion based and has been interpreted as the need to maintain blood flows Ͼ300 ml/min to ensure adequate dialysis. As a result of these guidelines, CVC often are run in the reverse configuration, thrombolytic agents such as thromboplastin inhibitor (t-PA) are used, or catheters are rewired when blood flow is reduced to Ͻ300 ml/min. With the increase in CVC prevalence and the corresponding increase in thrombolytic use and subsequent cost consequences, there is a clear need to clarify the relationship between CVC blood flow a...

Patterns of Hemodialysis Catheter Dysfunction Defined According to National Kidney Foundation Guidelines As Blood Flow <300 mL/min

“…Hemodialysis catheter dysfunction often is defined as blood flow rate (BFR) <300 mL/min [1], including in the National Kidney Foundation's Kidney Disease Outcome Quality Initiative (NKF-KDOQI) clinical practice guidelines [2]. Other definitions of catheter dysfunction reported in the literature include frequent arterial and venous pressure alarms, poor conductance, and poor dialysis efficiency based on urea reduction ratio or Kt/V calculations [3–8].…”

“…Since the recommendation to define catheter dysfunction as BFR <300 mL/min was opinion based, concerns have been raised that it has been interpreted to mean BFR must be kept above 300 mL/min to maintain adequate dialysis. However, one recent study showed that mean blood flows <300 mL/min were not commonly associated with dialysis inadequacy [1], prompting the authors to conclude that this definition of catheter dysfunction could result in a significant number of unnecessary interventions.…”

“…One exception is a study by Moist and colleagues on the association between BFR and dialysis adequacy, which found that mean blood flow <300 mL/min occurred in 10% of patients [1]. However, this was a cross-sectional study of only 259 patients conducted at two university-based tertiary hemodialysis care programs.…”

Correlation of arteriovenous fistula flow and hemodialysis adequacy

“…Naše istraživanje je pokazalo da se ovi pacijenti nisu statisti ki zna ajno razlikovali od pacijenta kod kojih je protok bio ve i od 600 ml/min ni u jednom pokazatelju isporu ene doze dijalize (Kt/V, URR, dužina dijalize, frekvenca dijalize). Do sli nih zaklju aka je došla i studija Moist i sar 6 . U njihovoj ispitivanoj populaciji pacijenta ak i pacijenti koji su imali protok manji od 300 ml/min su imali adekvatnu dijalizu de nisanu kao URR ve i od 65%.…”

Impact of Hemodialysis Catheter Dysfunction on Dialysis and Other Medical Services: An Observational Cohort Study

“…However, the impact of catheter dysfunction using a BFR threshold, such as in the NKF-KDOQI guidelines, has received less attention. One notable exception is a recent study examining the relationship between hemodialysis catheter BFR and dialysis adequacy in a cohort of 259 patients at two university-based centers [12]. The premise for this study was that since the NKF-KDOQI blood flow threshold for catheter dysfunction was opinion based [1] and has been interpreted to mean that maintaining BFR > 300 mL/min is necessary for adequate dialysis, it is important to better understand the association between BFR and dialysis adequacy.…”