[SU-PO363] Cardiac Output
(CO) Monitoring during Haemodialysis (HD) 
a Comparison between Saline
Dilution Method (Transonic), and a Noninvasive Method Based on Rebreathing of Inert Gas (Innocor).
Danny Jensen,
Jens Dam Jensen. Dept. of Nephrology C, Skejby, Aarhus University Hospital,
Aarhus,
Denmark
Monitoring of CO during haemodialysis (HD) is of
great interest, due to the cardiovascular effects of HD. Innocor
(I) is a new, non invasive portable device for assessing CO with built in pulse
oxymeter and multigas analyser. The device does all analyses of gas automatically
on site. The gasses used in the I device are: Sulfurhexaflouride
(SF6) 0,1% (measures lung volume) and N2O
0,5 % (measures pulmonal blood flow) and O2 25%
(variable). We compared CO measurement by I with
Transonic (T) in a controlled trial in which the sequence (T or I) was randomised. Twentyfive (m/f =
18/7) stable chronic HD pts age mean = 54(24 
79)
y were investigated. Dry weight = 68(42 - 96) kg. Mean patient access flow was
1110 
134(360
2775)
ml/min. Dialyser blood flow rate = 289 
10
(192 404)
ml/min. Mean Hct = 0,38 (0,31-0,46). Mean O2
uptake = 0,21 0,087
(0,08-0,49) L/min. Pulmonal shunt fraction = 8 8,4
(0 41)
%. All patients had stable A-V arm fistula with no local fistula recirculation.
We found a CO T = 5,9 0,35(3,9
- 10,5) L/min. CO I = 4,9 0,34(1,8
- 9,2) L/min. Mean delta CO (T I)
= 1,0 0,2(1,4
- 0,6) L/min (p< 0.001). The measurement repeatability of both methods
showed an identical coefficient of variance (sd/mean
CO), CVT = 6%, CVI = 7% in both high and low CO levels.
Pearson
s
linear correlation coefficient (COT vs. COI) = 0,84 (p<0.001). A linear regression showed COI
= 0,99*COT1
(r2 = 0,7). Nine (36 %) of our observations on delta CO were within 15%
limits of agreement in a Bland - Altman plot.
Access flow in % of CO correlated significantly with delta CO, Spearman rho = 0,68 (p<0,01).
Conclusion: We found a clear relationship between CO measured with T and I. Both demonstrated reproducible results. The I underestimates CO compared with T. This may be due to rapid
recirculation of N2O through the A-V fistula with interference of
pulmonary test gas exchange. The association between the difference in CO
measured by T vs. I - and access flow in % of CO supports this hypothesis.
Sunday, October 31, 2004 , 10:00 AM
Poster:
Cardiovascular Disease in Dialysis: Clinical Aspects (10:00 AM - 12:00 PM) Poster Board Number:
SU-PO363
[SU-PO368] Blood Flow in Brachiocephalic AVF Represents a Greater Percentage of
Cardiac Output Than That in Radiocephalic
AVF.
Wama van der Mark, P.
Boer, P.J. Blankestijn. Department of Nephrology, University Medical
Center Utrecht,
Utrecht, Netherlands
The flow in the arteriovenous (AV) access of hemodialysis patients means an
extra burden to the cardiac output (CO) and is therefore a risk factor for left
ventricular hypertrophy and heart failure. The aims of this study were to
quantify access flow and to assess the percentage of CO that passes through the
access and to compare the different types of accesses in this respect.
During a single hemodialysis session both CO and access flow were quantified by
the Transonic indicator dilution technique.
We performed 78 sets of measurements; 35 in AV fistulae forearm (radiocephalic), 29 in AV fistulae upper arm (brachiocephalic), and 14 in forearm PTFE grafts (in all
cases from brachial artery to cephalic vein).
In forearm AV fistulae, upper arm AV
fistulae and PTFE grafts, CO (meanse) was 5351315 mL/min, 6541364 mL/min and 4661349 mL/min (p<0.01 upper arm AV fistulae versus
others). Access flow was 966114 mL/min, 1693143 mL/min and 71577 mL/min (p<0.001 upper arm AV fistulae versus
others). Access flow represented 16.91.3%,
26.72.1%
and 15.51.4
% of CO. The percentage in upper arm AV fistulae was significant higher
(p<0.05) than in the two other groups. Blood pressure during measurements
did not differ between groups, indicating that vascular resistance in the arms
of patients with upper arm AV fistulae was lower than that in the other two
groups.
In conclusion, both in absolute terms and relative to CO flow in upper arm AV
fistulae is higher than in forearm AV fistulae and PTFE grafts. This is a
result of the lower vascular resistance in the arms of these patients. High CO
may mean an additional cardiovascular risk factor. The results underscore the
preference for radiocephalic AV fistulae over brachiocephalic AV fistulae as primary choice for vascular
access.
Sunday, October 31, 2004 , 10:00 AM
Poster: Cardiovascular
Disease in Dialysis: Clinical Aspects (10:00
AM - 12:00 PM) Poster Board Number: SU-PO368
|
[SA-PO309] High Flow
Fistula and Cardiac Hemodynamics.
Jennifer
M. MacRae, Thuan H. Do,
Debbie Rosenbaum, Adeera Levin, Mercedeh Kiaii.
Nephrology and Internal Medicine, University
of British Columbia, Vancouver, BC,
Canada
AVF creation is associated with a decrease in peripheral resistance and
increased cardiac output (CO). High output cardiac failure (HOCF), a rare
complication of high flow AVF, is defined as symptoms of CHF in the presence
of a high cardiac index (
3.0 L/min/m2). This study was to determine the prevalence of high flow AVF,
to document pt and AVF characteristics associated with high flow, and to
compare hemodynamic and echo parameters of high and normal AVF flow pts.
High access flow, Qa, was defined as > 2.0 L/min
10%
and normal Qa as 600 1500
ml/min. Qa, CO, central blood volume (CBV) and
total peripheral resistance (TPR) were measured in duplicate using ultrasound
dilution technique (HD02 Monitor Transonic Inc.) on the mid week dialysis run
in chronic stable HD pts. Echo was performed on the same day
.
19 % (46/242) of the AVF population had Qa>
2.0L/min. We report the results on 21 patients with high Qa
and 15 with normal Qa. High Qa
is associated with a younger age (55y vs 73y,
p<0.05), upper arm AVF (p=0.059), hx of a
previous AVF(p<0.05) and a higher PTH level.
Table 1 shows the hemodynamic and echo data for the
two groups.
Both CO and Qa/CO ratios are significantly higher
in the high Qa pts. In these pts we do not know the
overall risk of CV outcomes or at which degree of Qa
or Qa/CO this may occur. Prospective monitoring of Qa/CO in high flow pts is necessary to better understand
their potential cardiac risk and to develop intervention strategies.
|
|
BP mmHg
|
CO* L/min
|
TPR*
|
Qa* ml/min
|
Qa/CO*
|
LVMI
|
LVEF %
|
|
Normal Flow AVF (15
pts)
|
135/70
|
5.0(4.4-5.7)
|
17.8(16-20)
|
925(660-1110)
|
16(13-25)
|
102(93-142)
|
65(65-70)
|
|
High Flow AVF (21 pts)
|
143/76
|
8.1(6.5-14.8)
|
12.5(11-15.3)
|
2260(2100-3750)
|
32(26-38)
|
122(114-149)
|
65(60-65)
|
*p<0.05
Funding Source: Kidney Foundation of Canada
Saturday, October 30, 2004
, 10:00 AM
Poster:
Managing Hemodialysis Access Failure (10:00
AM - 12:00 PM) Poster Board Number: SA-PO309
|
[PUB239] Variation of
Hemodynamic Parameters during Hemodialysis Assessed by the Transonic Flow
Method.
Jens-Uwe
Kriete, Bernd Sucke, Werner
Riegel. Medizinische Klinik III, Klinikum Darmstadt, Darmstadt, Germany
Cardiovascular diseases are the leading cause of mortality in end stage renal
disease patients. Hypotensive episodes during hemodialysis have a major adverse
impact on the survival rate of hemodialysis patients. The main hemodynamic
compensatory mechanisms in patients undergoing dialysis are largely unknown.
The aim of this study is to investigate the intradialytic
stability of dialysis patients by measuring hemodynamic parameters. Cardiac
Output (CO), Cardiac Index (CI) and Peripheral Resistance (PR) are assessed by
means of Transonic Hemodialysis Monitor HD02.
We monitored CO, CI and PR every hour during dialysis sessions using Transonic
Hemodialysis Monitor HD02 (Diatec GmbH, Gilching, Germany).
Eleven stable patients who had been on renal replacement therapy for more than
one year were investigated. The achievement of dry body weight after dialysis
was assessed by ultrasound examination of the vena cava.
Data are given as mean SD.
Nine patients showed a decrease in CO (1.38, 0.75
l/min) and CI (0.73, 0.35)
and a parallel increase in the PR (6.56, 3.1
mmHg/l/min). The ultrafiltration rate of each patient varied between 362.5 ml/h
and 1300 ml/h. The ultrasound investigation of the vena cava after dialysis
showed inspiratory collapse in these 9 cases. We did
not detect blood recirculation in the vascular accesses of any patient. We
noticed an increase in the CO (1.35 l/min), CI (0.85) and a decrease of the PR
(4.55 mmHg/l/min) in 2 patients. A collapse of the vena cava was not observed
in these cases.
The Transonic Monitor HD02 is a convenient device for monitoring cardiovascular
parameters during dialysis. Patients who attained their dry body weight after
dialysis showed a moderate decrease in cardiac output and cardiac index and a
related increase in the peripheral resistance. These findings were not
correlated to the ultrafiltration volume. The observed increase in cardiac
output and cardiac index in patients who do not reach their dry body weight
could be interpreted as an improvement of heart function due to recompensation of fluid homeostasis.
Disclosure - Grant/Research Support: Fresenius Medical Care AG, Bad Homburg, Germany
Publication Only
[F-PO403] Monitoring of Dialysis Access
by Transonic Flow Studies Is Operator Dependent.
Jeffrey I. Silberzweig, Kathryn Osborn, Yvonne Noak.
Hemodialysis, The Rogosin Institute, New York, NY;
The Division of Nephrology, Weill Medical College of
Cornell University, New York, NY
Reductions in flow lead to subtle often unrecognized compromises in delivery of
dialysis and presage failure of the access device itself. Access flow can
therefore be considered a fundamental property of the access that should be
monitored1. K/DOQI guidelines call for surveillance of AV grafts by
intra-access flow and referral for fistulogram if the flow is less than 600 mL/min or there is a decrease in flow by more than 25% over
4 months2.
We initiated an intra-access flow monitoring program using the Transonic monitor in May 2002. Our program aimed to increase
the sensitivity of the test by using a cutpoint value
of a 10% decline in flow over one month. Between January 2002 and April 2004
(excluding January 2003 and February 2004), 1508 Transonic studied were done.
Of these, 239 showed at least 10% decline in flow from readings obtained one
month earlier. Of these, 127 were referred for angiograms; 127 (100%) patients
had abnormal stenotic abnormalities requiring percutaneous transluminal
angioplasty (PTA). Among the 1269 patients with normal studies, 4 (0.32%) had a
graft thrombosis. These data indicate a sensitivity of 96.95% and a specificity
of 100%.
The success of our monitoring program led to a dramatic reduction in dialysis
graft thromboses. Patients profited by a marked reduction in the need for
dialysis access via femoral catheterization. During the six months prior to
initiating the monitoring program, 17 patients required femoral catheterization
for access thromboses; two years later, only 2 such procedures were done.
References:
1. Depner, TA, et.al., ASAIOJ, 541, 1995, 745.
2. National Kidney Foundation, AJKD, 37 Suppl.,
2001, S150
Friday, October 29, 2004 , 10:00 AM
Poster: Hemodialysis Access
Failure (10:00 AM - 12:00 PM)
Poster Board Number: F-PO403
[SU-PO270] Cardiovascular
Stability of Intermittent 
Single Pass
Batch Dialysis
a
Prospective Study Using the Transonic Flow Method.
Bernd Sucke,
Jens-Uwe Kriete, Werner Riegel. Medizinische Klinik III, Klinikum Darmstadt, Darmstadt, Germany
Single
Pass Batch Dialysis
(Genius) is a successfully established renal replacement technique in end stage
renal disease patients. It is supposed to be associated with less severe
decline in blood pressure and lower increase of pulse rate compared to
conventional hemodialysis.
This study compares the intradialytic hemodynamic
changes in patients undergoing Genius dialysis and conventional intermittent
hemodialysis.
Ten patients (3 women, 7 men) received alternating intermittent Genius dialysis
and conventional hemodialysis (Fresenius 4008, each Bad
Homburg, Germany) randomly.
Patients had been on chronic renal replacement therapy for more than one year.
Cardiac Output (CO), Cardiac Index (CI) and Peripheral Resistance (PR) were
monitored once an hour during the dialysis session. Measurements were performed
by the Transonic Flow method (Diatec GmbH, Gilching, Germany) using a hemodilution technique. Prior to dialysis a recirculation
in the vascular access was excluded. The achievement of dry body weight after
dialysis was controlled by ultrasound investigation of the inferior vena cava.
Data are given as mean SD.
Eight patients showed a decrease in CO (F4008 vs
Genius: 1.21 0.59
vs1.3 0.69
l/min), CI (0.66 0.3
vs 0.71 0.39)
and an increase in PR (5,77 2.28
vs 5,53 3.95
mmHg/l/min) at the end of the dialysis session. These 8 patients achieved their
dry body weight at the end of dialysis. Two patients showed an increase in CI
and a decrease in PR during conventional dialysis. Both patients failed to
attain their dry body weight. Remarkably, 4 patients showed a transitory
decline in PR (2 1.08
mmHg/l/min) after starting Genius dialysis session.
Focussing on cardiovascular stability, intermittent
Genius dialysis seems to be an appropriate alternative to conventional
dialysis. There are no significant differences of the hemodynamic parameters
during dialysis comparing both techniques of renal replacement therapy when dry
body weight at the end of dialysis was achieved. The transitory decline of the
PR in 4 patients receiving Genius dialysis may be explained by the contact of
blood to warm dialysate at the beginning of the treatment.
Disclosure - Grant/Research Support: Fresenius Medical Care AG, Bad Homburg,
Germany
Sunday, October 31, 2004 , 10:00 AM
Poster: Hemodialysis: Body
Composition and Hemodynamics (10:00 AM - 12:00 PM)
Poster Board Number: SU-PO270
|
[F-PO398] Myths and
Realities of Vascular Access Surveillance Programs during Hemodialysis (HD).
Nikolai
M. Krivitski. Engineering, Transonic Systems
Inc., Ithaca, NY
Since the introduction of intra-access pressure and flow measurement
techniques, a large body of literature on access surveillance has been
produced. Recently, the efficacy of access surveillance has been debated. The
purpose of this abstract is to summarize papers on access surveillance
techniques with respect to the ability to identify stenosis and thrombosis.
Criteria for inclusion: 1) papers from peer-reviewed journals or books (no
abstracts); 2) independent studies only--papers by authors and companies that
invented the surveillance technology were not included. Results are presented
in the Table.
|
Summary of results of vascular access surveillance trials
|
|
Surveillance
|
Dynamic venous pressure
|
Static venous pressure
|
Access flow during HD
|
|
Independent studies
|
10
|
7
|
22
|
|
Number of accesses
|
AVG=748 AVF=150
|
AVG=353 AVF=84
|
AVG=1501 AVF=1246
|
|
Investigated stenosis
|
positive=4* negative=1*
|
positive=3* negative=0*
|
positive=11*
negative=0*
|
|
Investigated thrombosis
|
positive=4* negative=6*
|
positive=2* negative=4*
|
positive=12*
negative=5*
|
|
Major problems with
some studies and technologies
|
Wrong basic theoretical
assumption
|
Wrong basic theoretical
assumption
|
Not following both
K/DOQI threshold guidelines; PTA failure
|
* authors
conclusions on surveillance outcomes; only papers included-no abstracts; some
studies had both positive and negative conclusions on stenosis and/or
thrombosis.
Among 10 studies that used only one flow threshold, a positive conclusion was
reached in 7 studies and a negative conclusion was reached in 3 studies.
Among 12 studies that used both absolute and trended access flow thresholds
(analogous to the K/DOQI guidelines), 10 had positive conclusions about flow
surveillance and stenosis detection or thrombosis prediction. Two presented
negative conclusions--one identified PTA failure, and the other had results
that are in dispute.
The summary of 17 independent intra-access pressure clinical studies does not
support the statement that static pressure is a better surveillance tool than
dynamic venous pressure. Analysis of 22 access flow studies shows that it is
more efficacious to use both absolute and trended thresholds, as promoted by
the K/DOQI guidelines, to achieve positive outcomes.
Scientific Advisor: Employee of Transonic Systems
Inc.
Friday, October 29, 2004
, 10:00 AM
Poster:
Hemodialysis Access Failure (10:00
AM - 12:00 PM) Poster Board Number: F-PO398
|
[SU-PO275] Hemodynamic Stability during
Pre-HDF and Lowflux HD at Temperature Controlled
Conditions Using High Calcium-Ion Dialysis and Replacement Fluid. A Blinded
Randomized Controlled Study.
Danny Jensen, Nikolaos Karamperis, Jens D.
Jensen. Dep. of Nephrology C, Skejby, Aarhus University Hospital,
Aarhus,
Denmark
Convective therapy is thought to result in better hemodynamic stability than
conventional low flux hemodialysis (HD). We compared HD with high dose pre-hemodiafiltration (HDF) in 13 dialysis patients (pts), mean
age 49 y (26-76). Pts with NYHA > II were excluded. Pts were randomized to
either HD followed by pre-HDF (4
h) or vice versa. The dialysis modality was blinded. Substitution fluid volume
in HDF was 1,2 L/kg dry weight (83 2L).
Ca-ion fluid concentration was 1,75 mM. Arterial temperature (atmp)
was locked at pt temp. at dialysis start. Cardiac
output (CO) was measured hourly during the sessions using the Transonic Flow QC
saline dilution method.
Mean blood pressure (MBP) change during HD (end vs. start) was -0,52 2,6
mmHg (ns) and -2,8 3,1
mmHg (ns) during HDF. MAP decrease HD vs. HDF (ns). CO decreased during HD from
6,9 0,5
L/min to 6,1 0,44
L/min (p<0,05) and during HDF from 7,4 0,24
L/min to 5,9 0,52
L/min (p<0,01). CO decrease in HD vs. HDF (ns). The stroke volume (SV)
during HD declined 5 6
mL (ns) and 14 6
mL (p<0.05) in HDF. SV decline HD vs. HDF was 10 6
mL (ns). Total periferal
resistance (TPR) increased in HD by 2,2 1,2
mmHg
min/L
(ns) and in HDF by 2,8 0,7
mmHgmin/L
(p<0,01). The differences in TPR increase in HD vs
HDF was 0,6 1,1
mmHgmin/L
(ns). Pulse rate (P) during HD decreased 6 2
bpm (p<0,05) and 3 5
bpm (ns) during HDF. Diff. in P decreases between
modalities (ns). Energy loss (cooling) during HD = 228 41
kJ and during HDF = 207 40
kJ (ns). The atmp was kept constant 36,6 0,1
C
in HD and 36,5 0,1C
in HDF. Ultra filtration (UF) was 3,3 0,4
kg in HD and 3,1 0,2
kg in HDF. Decrease in blood volume HD=10 1%
in HD and 11 1%
in HDF. Kt/V in HD was 1,6 0,1,
and 1,8 0,1
in HDF.
In conclusion, a decrease in SV during HDF in high calcium
treatment at temp. controlled, UF and Kt/V
matched conditions was found. CO decreased equally in both modalities. MBP did
not decrease significantly in any modality. TPR increased only during HDF, and
no TPR difference between HD and HDF could be demonstrated.
Sunday, October 31, 2004 , 10:00 AM
Poster: Hemodialysis: Body
Composition and Hemodynamics (10:00 AM - 12:00 PM) Poster Board Number: SU-PO275
|
[F-PO399] How Well Does
Access Blood Flow (Qa) or Decreases in ABF ( Qa) Predict Arteriovenous
Graft (AVG) Thrombosis?
Brian
M. Murray, Neeraj Singh. Medicine, University at
Buffalo, Buffalo, NY
Access surveillance with Qa or Qa has been recommended by DOQI to prolong AVG survival ,
but it,s utility for this purpose has been
challenged (Paulson, AJKD35: 1089, 2000). We conducted a prospective
non-interventional study in which 43 patients with functioning AVGs had Qa (by Transonic HD02
meter) measured on 3 occasions, 1 month apart, and were then followed for a
further 6 months (without further Qa measurements).
Five patients were excluded from the analysis ( 1
AVG clotted before the second measurement, 2 missed Qa
measurements due to hospitalization, 2 underwent fistulograms(with
angioplasty) for clinical indications). None of the other 38 AVGs had any intervention during the 6 month study period
except for AVG thrombosis. There were 7 episodes of thrombosis (18%). We
compared the ability of either a Qa < 600ml/min,
a Qa >20%, the presence of both
criteria or either criterion to predict thrombosis over a 6 month
follow-up period. Table 1 shows the sensitivity, false positive rate and
post-test probability of thrombosis for each testing criterion.
|
Predicting thrombosis within 6 mos
|
|
Criterion
|
Sensitivity
|
False positive rate
|
PostTest Probability after a PTR
|
PostTest Probability after a NTR
|
|
Qa <600
|
57%
|
19%
|
50%
|
10%
|
|
Qa>20%
|
86%
|
13%
|
59%
|
3%
|
|
Either
|
86%
|
29%
|
39%
|
4%
|
|
Both
|
50%
|
9%
|
55%
|
18%
|
PTR=positive test result,NTR=negative
test result
It can be seen that Qa performed the best with a sensitivity of 86% and a
false positive rate of only 13%, values that would meet those recommended by
Paulson. If the presence of either a Qa<600 or Qa >20% were used then there was no improvement in
predictive ability because of the increase in false positive rate to 29%.
This may have been due to inclusion of patients with low but stable Qa that did not thrombose. On
the other hand, requiring that both criteria be satisfied resulted in a
decrease in sensitvity (to 50%) with only a minimal
improvement in the false positive rate (9%). These data support the proposal
of Neyra et al. (KI 54:1714, 1998) that a decrease in Qa
may be the best predictor of intermediate term graft thrombosis.
Friday, October 29, 2004
, 10:00 AM
Poster:
Hemodialysis Access Failure (10:00
AM - 12:00 PM) Poster Board Number: F-PO399
|
[PUB195] Clinical Evaluation
of Blood Flow Direction in Hemodialysis Graft Protheses.
Roman Fiedler, Matthias Pfau, Bernd Osten, Thomas Langer.
Department of Nephrology, Martin-Luther-University Halle-Wittenberg,
Halle (Saale), Germany;
Department of Internal Medicine, St. Elisabeth and St. Barbara Hospital Halle, Halle (Saale),
Germany
The trouble-free use of hemodialysis (HD) shunts is the absolute need for an
effective dialysis treatment. Especially in graft loops the confusion of blood
flow direction (BFD) with following recirculation can not be excluded in
clinical practice, if surgical report is not available. The aim of this study
was to prove a simple clinical method for the evaluation of BFD in HD graft protheses.
Forty-seven HD patients, aged 61 [range: 30-80] years, with a graft prothesis were recruited. The mean dialysis duration of the
patients was 68 [range: 2-253] months, and the graft prothesis
types were Loops
(78,7 %), Straights
(14,9 %), and Colliers
(6,4 %). We investigated for the determination of BFD the simple but safe
clinical method of auscultation prior to shunt puncture and compared it to HD01
(Transonic Inc., USA),
a conventional ultrasound hemodilution method during
HD.
In all grafts blood flow as well as recirculation were
measured by HD01,
and so BFD was fixed. The shunt noises, which were auscultated
by stethoscope (n=47) and recorded as wave file by a microphone computer system
(n=32), showed a characteristic stenosis effect by finger press on the graft
flow upwards, whereas the noises were scarcely changed by finger press on the
graft flow down. Clinical evaluation of BFD was correct in 88 %, impossible in
10 % of the cases and wrong in 1 patient. The study also verified that in 6
patients (12,8 %) dialysis blood tubes were connected
always contrary to BFD in the graft. The determined mean recirculation rate was
24,2 %.
From our results we can conclude that the auscultation is a simple sure and
easy method for the detection of BFD in grafts, if the investigation is prior
to shunt puncture and access blood flow is higher than 400 ml/min. Additional
cost and time will be saved in comparison to HD01
and/or duplex sonography.
Publication Only
|
[F-PO400] Why Don t Some Arteriovenous
Grafts (AVGs) with Low Access Blood Flow (Qa) Clot?
Brian
M. Murray, Neeraj Singh. Dept Of Medicine,
University at Buffalo, Buffalo, NY
Previous studies have suggested that a low Qa(<600ml/min) is
suggestive of imminent AVG thrombosis, but many AVGs
with Qa <600 can maintain patency for a
relatively prolonged period of time. The reason for this is not clear. We
recently measured Qa and cardiac output (CO) (by
Transonic HD02 meter) on 3 occasions, 1 month apart, in 43 patients with
functioning AVGs, who were then followed for a
further 6 months (without further measurements). Ten of the 43 patients had a
value <600ml/min on at least one occasion. Four of these ten AVGs subsequently thrombosed
during the follow-up period, whereas the remaining four remained patent. We
compared a number of clinical parameters between those AVGs
that clotted and those remaining patent (see table 1). The only differences
that reached statistical significance were the ratio of Qa
to CO and the delta Qa (defined as the % change in Qa between the initial and final measurement).
|
Table 1
|
|
|
Thrombosed AVGs (n=4)
|
Patent AVGs(n=6)
|
|
Patient Age (yrs)
|
536
|
6913
|
|
Age of AVG (mo)
|
3339
|
124
|
|
IAP
|
0.630.29
|
0.740.21
|
|
DVP mmHg
|
11821
|
11014
|
|
CO L/min
|
5.40.9
|
4.61.0
|
|
First Qa
|
687113
|
533123
|
|
Qa/CO
|
0.080.02
|
0.12.02*
|
|
Delta Qa
|
-33%17%
|
-4%14%*
|
IAP=intra-access pressure ratio, DVP=dynamic venous
pressure,*P<.05)
The AVGs that clotted were those that exhibited a
fall in Qa during the 2 month measurement period
rather than those AVGs that exhibited stable albeit
low Qa. As a result, the initial Qa tended to be higher in the AVGs
that subsequently clotted.Grafts that remained
patent also tended to have a higher Qa/CO ratio,
i.e. Qa accounted for a greater percentage of the
CO. This may have reflected the fact that the  patent
AVGs tended to belong to older patients with lower
cardiac outputs, though neither of these differences reached statistical
significance. It is possible that in these patients the low Qa was in part due to poor cardiac performance as much as
a progressive stenosis. In conclusion, while Qa<600
indicates an increased risk of thrombosis; within this group, it is the AVGs with falling Qa that are
most likely to clot.
Friday, October 29, 2004
, 10:00 AM
Poster:
Hemodialysis Access Failure (10:00
AM - 12:00 PM) Poster Board Number: F-PO400
|
|
|
[SA-PO313] Meticulous Medical Care
Provides Minimum of Complications and Excellent Survival of Tunneled Central
Venous Catheters.
Henrik Mulec, Eva-Lis Henriksson, Elisabeth Fransson, Per Dahlberg. Department of
Dialysis and Medicine, Med Clin Northern
Alvsborg Hospital, Trollhattan, Sweden
Prospective observational study on complication rate (Infection rate, Blood
flow obstruction) and technique survival of tunneled central venous catheters
(CVC). A single
center experience.
From 1999 until December 2003 69 patients received 90 ASH split catheters
inserted with few exception in right jugular vein with the tunnel to the chest.
One operator performed the procedure by ultra sound guidance. Antibiotics were
used at the time of insertion. There were 72 primary insertions and 18
catheters were changed in the same vein. There were no per operative
complications. Patients were 34 women and 35 men. Mean age was 6514
years and 25% of patients were diabetics. Follow up was 35237 catheter days.
During first 3 months the same nursing team responsible for the patient was
responsible for the optimal fixation of the catheter, the team changed the
catheter dressing 1/week and after 3 months the dressing was minimal consisting
of a tape for fixation. At the start of dialysis the luer
lock connection was disinfected by iodopax or chlorhexidin. Heparin 5000 IU/ml was used as locking
solution with routine local use of alteplase 1 mg /ml
once a month and at blood flow <200 ml/min. Maximal possible blood flow was
measured regularly with TRANSONIC technique and was 280 ml/min allowing Kt/V
1.6.
Mean survival time for catheters (dialysis with one and the same catheter) was
(Kaplan Meier) 557 62
days. Technique survival, time the patients were dialyzed by CVC was 736 79
days. Catheters not needed and catheters in dead patients were censored. There
were few local, exit site infections: 0.7/year or 1/515 catheter days and even
less blood stream infections: 0.32/year or 1 /1156 catheter days!
Major long-term complication was the development of vena cava superior syndrome
in 3 patients and catheter brake at 4 occasions after 1.5 and 3 years of use
respectively.
Good medical care of the tunneled CVC is associated with low infection rate,
with excellent catheter survival and blood flows for adequate dialysis.
Saturday, October 30, 2004 , 10:00 AM
Poster: Managing Hemodialysis
Access Failure (10:00 AM - 12:00 PM)
Poster Board Number: SA-PO313
[F-PO406] Arteriovascular
Access Flow Monitoring Via the Ultrasound Dilution Technique Reduces Vascular
Access Complications.
Bruno Paris, Sylvie Lavaud, Christine Randoux, Philippe Rieu, Jacques
Chanard. Nephrology,
University Hospital,
Reims,
France
Introduction: Hemodialysis vascular access-related complication is an
important cause of dialysis patient hospitalization. Sequential prospective
monitoring of arteriovenous access flow may detect incipient access malfunction
and prevent vascular access morbidity.
Method: We retrospectively studied the incidence of vascular access
complications (thrombosis, angioplasty, hospitalisation)
during two periods in a chronic hemodialysis population at Reims
Hospital. In the first
period (2001, 84 patients), access flow was not monitored. In the second period
(2003, 142 patients), access flow was assessed every 3 months via the
ultrasound dilution technique. Detection of vascular access stenosis was always
associated with preventive angioplasty.
Results: During the two study periods: 1) detection of vascular access
stenosis was increased from 0,42 (period 1) to 0,53 (period 2) events / patient
/ year (p< 0,05), 2) vascular access thrombosis rate was reduced from 0,250
(period 1) to 0,126 (period 2) events / patient / year (p< 0,02), and 3)
hospital days related to vascular access-related complications was decreased
from 1,52 (period 1) to 1,15 (period 2) days / patient / year (p< 0,02). 95%
of thrombosis occurred in patients with synthetic arteriovenous fistulas.
Conclusion: Our data shows that detection of vascular stenosis by
prospective monitoring of arteriovenous access flow, when coupled with
preventive angioplasties, reduces by 50% the risk vascular access thrombosis.
Prevention of vascular access morbidity was associated with a decreased in the
number of hospitalisations.
Friday, October 29, 2004 , 10:00 AM
Poster: Hemodialysis Access
Failure (10:00 AM - 12:00 PM)
Poster Board Number: F-PO406
[F-PO404] Monthly Access Flow
Monitoring Did Not Improve Cumulative Access Survival.
Hassan Shahin,
Reddy P. Geeta, Bradley S. Franzwa,
Bradley S. Dixon. Internal Medicine, University
of Iowa College of Medicine, Iowa City, IA; Research, Veterans Administration Medical Center,
Iowa City, IA
Regular access monitoring is recommended to detect and treat access stenosis in
order to prevent access thrombosis and failure. In 1999, we instituted a program
of regular monthly access flow (Qa) monitoring using
the ultrasound dilution technique (UDT). In a sequential observational trial,
300 pts were studied for the impact of UDT on survival of the first placed
arteriovenous access (native fistulas, AVF 
prosthetic
grafts, AVG). Group 1, the historic group (before 1999), had 204 AV accesses,
72% AVF, followed for 382 access-yrs. Group 2, the UDT monitored group, had 95
AV accesses, 80% AVF, followed for 168 access-yrs. Decision to refer for
angiography was based on clinical criteria for Group 1, and clinical criteria
plus results of UDT in Group 2; i.e. Qa <400 (AVF)
or <600 (AVG) ml/min or Qa>25% in sequential studies. We found that Group 2 had
an increased rate of angioplasties (meanSD=1.071.8
vs 0.521.9
per access-yr, p=0.005) but no change in radiological thrombosis events (0.611.8,
Group 2 vs. 0.662.3,
p=0.94). Surgical procedures were higher in Group 1 (0.893.0,
Group 1 vs 0.371.3
per access-yr, p<0.01). Overall, the primary unassisted patency was not
statistically different between the two groups but cumulative patency was
better in Group 2 even after adjusting for differences in baseline
characteristics (p=0.02). However, the improvement in cumulative patency in
Group 2 all occurred prior to initiation of access monitoring (median=139 days
after access creation). Comparing outcomes in Group 2 patients after initiation
of flow monitoring with Group 1 patients whose access survived at least 139
days, primary unassisted patency tended to decrease after initiation of access
monitoring in Group 2 (p=0.09) and there was no difference in cumulative patency
after flow monitoring. We conclude that UDT monitoring is associated with an
increased incidence of angioplasty procedures with a trend towards shorter
primary patency, but did not decrease the radiological thrombosis rate or
improve cumulative access patency.
Friday, October 29, 2004 , 10:00 AM
Poster: Hemodialysis Access
Failure (10:00 AM - 12:00 PM)
Poster Board Number: F-PO404
[SU-FC077] Forearm Blood Flow Reserve
Predicts Successful Maturation of AV-Fistulae.
Joke van der Linden, Anton H. van den Meiracker, Dammis Vroegindeweij,
Andre A.E.A. de Smet, Thomas W. Lameris, Marinus A. van den Dorpel. Internal
Medicine, Medical Center Rijnmond-Zuid, Rotterdam, Netherlands; Internal
Medicine, Erasmus Medical Center, Rotterdam, Netherlands; Radiology, Medical
Center Rijnmond-Zuid, Rotterdam, Netherlands; Surgery, Medical Center
Rijnmond-Zuid, Rotterdam, Netherlands
The autologous AV-fistula is the vascular access of choice in hemodialysis
patients because of superior long-term survival due to a lower risk for
thrombosis and infection. Access surgery should be followed by
adequate fistule maturation, i.e. a gradual increase
in vessel diameter, and thus increase in access flow. We hypothesised
that preoperative measurement of the arterial forearm blood flow (FBF) reserve
predicts successful fistula development. Prior to surgery, we measured FBF
during incremental infusion of both an endothelium-dependent vasodilator, metacholine (MCh), and an
endothelium-independent vasodilator, sodiumnitroprusside
(SNP), using venous occlusion plethysmography. Twentyone patients (age 62
3,(mean sem), 10M /11F ) with end-stage renal failure awaiting
access surgery were studied. In patients with successful AVF maturation (n=17)
the AUC of both vasodilators was higher than in patients with AVF failure
(n=4)( MCh: 122.29.8
U vs. 79.15.8,
p<0.05; SNP: 255.919.4
vs. 127.829.4,
p<0.01). The absolute FBF increase was also significantly different between
both groups (MCh:10.30.9
vs. 6.21.0
mL/100mL/min, p=0.03; SNP: 11.81.1
vs. 5.41.4
mL/100mL/min, p<0.01). No AVF failure was observed when AUC was above 100 U
after MCh (n=11)(p<0.05),
or when AUC was above 200 U after SNP (n=13) (p<0.01). Baseline MAP and FBF
was not different (1074
vs. 1095
mmHg, N.S.; 3.40.7
vs.4.60.4,
N.S.). Duplex radial artery diameter did not differ between patients with
successful or unsuccessful AVF maturation (2.40.2
vs 2.80.3,
N.S.). We conclude that with measurement of FBF reserve, successful or
unsuccessful AVF maturation can be predicted accurately. Endothelial function
does not seem to play a role, as endothelium-dependent and -independent
vasodilators had similar effects. In addition to anatomical mapping, functional
preoperative evaluation may improve AVF outcome.
Sunday, October 31, 2004 , 4:30 PM
Free Communication:
Prevention and Correction of Access Problems (4:00 PM-6:00 PM)
[F-PO530] Extravascular Lung Water and Peripheral
Volume Status in Hemodialysis Patients with a History of Heart Failure and
without.
G. Joseph, J. M. MacRae, A. P. Heidenheim, R. M. Lindsay. Medicine, University
of Western Ontario, London, ON, Canada; University
of British Columbia, Vancouver, BC, Canada
Hemodialysis (HD) patients are generally extracellularly
volume expanded. HD patients with a history of congestive heart failure (CHF)
may be more so. A technique to measure extravascular
lung water (EVLW) using blood ultrasound velocity changes following injections
of 0.9% and 5% saline has been described. We used this technique in stable HD
patients and determined their range of EVLW. We questioned the relationship
between volume expansion and EVLW in HD patients with and without a history of CHF
and in those with CHF.
We studied 29 stable HD patients, 12 with a history of CHF and 17 without. All
were clinically euvolemic. Intracellular fluid (ICF)
and extracellular fluid (ECF) were measured prior to
initiation of HD using bioimpedance spectroscopy.
EVLW was measured in early dialysis using blood ultrasound dilution. The values
for EVLW were 3.55 ml/kg 0.94
(M SD)
in patients without a history of CHF and 3.88ml/kg 0.82
in patients with a history (NS). These values are similar to those previously
obtained. The ECF/ICF ratio was higher in those with a history of CHF (1.27 0.29)
compared to those without (1.04 0.04)
(p = 0.013). These ECF/ICF ratios are higher than those found in healthy
subjects (0.440.74)
indicating ECF volume overload in both groups, but more so in those with a
history of CHF. There was a positive correlation between EVLW and ECF/ICF
ratios (r =0.54; p=0.003) indicating that ECF volume expansion is associated
with increased EVLW. EVLW measurements were made in two patients who were
clinically in pulmonary edema. Their EVLW were higher than those not in
pulmonary edema (7.95 ml/kg and 5.95 ml/kg, p <0.05).
This study shows: 1) that HD patients with a history of CHF are ECF volume
overloaded (even when judged euvolemic), to a greater
extent than those without; 2) that the degree of ECF expansion is associated
with increasing EVLW volumes even without pulmonary edema and; 3) that
eventually ECF volume expansion exceeds limits and pulmonary edema occurs. We
surmise that these developing technologies will become of clinical value.
Friday, October 29, 2004 , 10:00 AM
Poster: Complications of
Hemodialysis I (10:00 AM - 12:00 PM)
Poster Board Number: F-PO530
[SU-FC080] A Six Year Study of Risk of
Hemodialysis Graft Thrombosis: An Analysis Based upon the Repetitive
Longitudinal Nature of Flow Surveillance.
Sunanda J. Ram, Neville R. Dossabhoy,
William D. Paulson. Medicine, LSU Health Sciences Center, Shreveport, LA;
Medicine, Medical College of Georgia, Augusta, GA
During graft surveillance, a decrease in blood flow (Qa)
is widely used to assess risk of thrombosis. To our knowledge, however, no
studies have taken into account the repetitive longitudinal nature of Qa measurements. In this 6 year prospective study, we
performed 1,842 monthly Qa measurements by ultrasound
dilution on 129 patients. We assessed risk of thrombosis associated with
monthly determinations of percentage decrease in Qa (
Qa) computed over rolling intervals of 3 months. Qa measurements were not criteria for referral for
interventional procedures during the study. Risk of thrombosis was determined
during the 30 or 90 days after each Qa. Forty-one thromboses occurred within 30 days of 1,036 Qa determinations; 84 thromboses occurred within 90 days of
986 Qa determinations. The figure shows risk of thrombosis in
relation to range of Qa values.
The figure demonstrates that risk of thrombosis in the next 30 or 90 days was
small unless Qa was 40%.
We also found that 50% of all thromboses were preceded by Qa <20%.
Conclusion: This study shows that risk of thrombosis associated with a single Qa determination is small unless Qa is large. Moreover, half of all thromboses are not
associated with a significant decrease in Qa. A
surveillance protocol that consists of repetitive longitudinal determinations
of Qa does not provide an accurate assessment of risk of
thrombosis.
Sunday, October 31, 2004 , 5:15 PM
Free Communication:
Prevention and Correction of Access Problems (4:00 PM-6:00 PM)
[F-PO391] The Natural History of Autogenous Radio-Cephalic (RC) Wrist Arteriovenous Fistulas
(AVF): A Five-year Prospective Observational Study.
Carlo Basile, Giovanni Ruggieri, Luigi Vernaglione, Alessio Montanaro, Rosa
Giordano. Division
of Nephrology, Miulli General Hospital, Acquaviva delle Fonti, Italy; Division of Nephrology, Martina Franca
Hospital, Martina Franca, Italy
Clinical practice guidelines have supported vascular access (VA) surveillance
programs on the premise that the natural history of the VA will be altered by
radiological or surgical interventions. The primary objective of this
prospective observational study was to follow the natural history of autogenous RC wrist AVFs for 5
years without any preemptive interventions.
We enrolled 52 randomly selected adult prevalent hemodialysis (HD) patients.
The protocol prescribed avoiding any surgical or interventional radiological
procedures until VA failure (AVF thrombosis or a VA not assuring a single-pool
Kt/V>1.2). The subjects underwent yearly assessments of VA blood flow
rate (Qa) by means of a saline ultrasound dilution
method.
All failures of VA were due to AVF thrombosis: it occurred in 9 cases, i.e. a
rate of 0.035 AVF thrombosis per patient-year at risk.
A ROC curve, evaluating the diagnostic accuracy of baseline VA Qa values in predicting AVF failure, showed an
under-the-curve area of 0.820.05
SD (p = 0.01). The value of VA Qa, identified as a
predictor of AVF failure, was<700 ml/min with an 88.9% sensitivity and 68.6%
specificity. When subdividing AVFs into two groups
according to the baseline VA Qa, 2 out of the 9
thromboses occurred among the AVFs that had baseline Qa>700 ml/min (n = 31), whereas 7 occurred among the AVFs that had baseline Qa<700
ml/min (n = 21). The 5-year cumulative actuarial survival was 75.0% and 26.0%,
respectively (log-rank test, p=0.006). The 18 AVFs
that remained patent at the end of the 5 years maintained a median Qa>900 ml/min at all time points studied.
In conclusion, this study shows a very low rate of AVF thrombosis per
patient-year at risk and a high actuarial survival of autogenous
RC wrist AVFs, particularly of those having a Qa>700 ml/min. Thus, a VA Qa<700
ml/min appears to be a reliable cut-off point at which to start a closer
monitoring of this parameter which
may lead to further investigations and possibly interventions relevant to the
function of the AVFs.
Friday, October 29, 2004 , 10:00 AM
Poster: Hemodialysis Access
Failure (10:00 AM - 12:00 PM)
Poster Board Number: F-PO391
[PUB206] One Year
Experience of an Endovascular Program Managed by Nephrologists at an Academic Center.
Arif Asif, Donna
Merrill, Florin Gadalean, Galo
Garces, Gautam Cherla, Patricia Briones, Jan Tawakol, Cristovao Vieira, David
Roth. Nephrology and Hypertension, University
of Miami, Miami, FL
Hemodialysis (HD) vascular access (VA) management is a critical aspect of the
care of the end stage renal disease population. Surgeons and interventional
radiologists have traditionally provided this care. Frequently, VA-related
procedures do not receive the highest priority by these specialists.
Nephrologists are becoming acutely aware of the need for improvements to VA
care. To respond to VA-related issues, we initiated a HD VA program. After
completing optimal training in endovascular procedures the nephrologist
developed a team to assist with various aspects of the procedures. An
endovascular procedure room was established within an outpatient dialysis
facility. VA surveillance was implemented using ultrasound dilution technique
in order to identify patients with VA dysfunction. Procedures are performed on
an outpatient basis and VA teaching is routinely provided before and after the
actual procedure. Patients are scheduled on their dialysis or non-dialysis day
according to their preference, minimizing inconvenience and transportation
issues. Thus far; we have successfully completed 430 procedures in a one year
period (06-03 to 05-04).
The procedures included percutaneous balloon
angioplasty (n=172), vein mapping (n=43), salvage of undeveloped fistulae
(n=20), vein obliteration (n=10), declotting
procedure (n=24), venous stent placement (n=1), tunneled hemodialysis catheter
placement (n=46), angioplasty of fibrin sheath (n=16) and tunneled catheter
removal procedure (n=48). Our cumulative procedure-related complications
included grade I hematoma (n=6), severed micropuncture sheath (n=1) and pneumothorax
(n=1). None of these required surgical intervention. This approach has been
enthusiastically received by the patients who routinely had suffered
procedure-related treatment delays prior to the initiation of our program. We
propose that nephrologists should become more involved in the management of VA.
In addition, we feel that outpatient HD facilities are a prime location for
initiation of such a program.
Publication Only
[PUB209] Long Term
Follow-Up of Percutaneous Treatment Vascular Access
Dysfunction.
J.A. Herrero, F. Coronel, J.V. Mendez, E. Santos, J.J. Gallego, C. Gamez,
S. Cigarran, N. Calvo, A. Barrientos. Nephrology, Hospital Clinico San Carlos, Madrid, Spain;
Radiology, Hospital Clinico San Carlos, Madrid, Spain
Vascular access thrombosis is one of the most morbid problems encountered by
hemodialysis patients. The purpose of the study was to assess the long term
usefulness of a program for the detection and percutaneous
treatment of vascular access dysfunction and to compare between the different
types of arteriovenous fistulae (AVF). Detection was based on physical
examination, blood flow, venous pressure, dialysis efficiency and recirculation
measurements as a indicated NKF-DOQI guidelines. Percutaneous
treatment consisting of angioplasty (PTA) or PTA plus stent deployment when the
residual stenosis was >50%.
From october-90 to march-03 we have performed 559 procedures in 281 AVF (235
patients). The AVF were: 141 radial-cephalic (RC), 52 brachial-cephalic (BC)
and 88 polytetrafluoroethylene grafts (PTFE). The
most frequently indicators of dysfunction were decreased blood flow rate in RC
(65%) and increased venous pressure in BC and PTFE (72 % and 76 % respectively).
Technical success rate for PTA was 77 % in RC, 45 % in BC and 47 % in PTFE ( p<0.001 of RC versus BC and PTFE). With stent
deployment technical success rate was 98 % in all types of AVF. The primary
patency rate of all AVF at 1 and 5 years was 52 % and 28 % respectively,
whereas the assisted patency rate (more of 1 procedure/AVF) was 82 % and 49 %. Reinterventions were 2.75 procedures/AVF in BC, 2.22
procedures/AVF in PTFE and 1.57 procedures/AVF in RC (p=0.01 versus BC and
PTFE). The period of reintervention was 170 days in
BC, 204 days in PTFE and 304 days in RC (p<0.001 versus BC and PTFE).
Assisted patency rate at 1 and 5 years was also different when compare the AVF
types: RC 88 % and 79 %, BC 83 % and 16 %, PTFE 73 % and 22 % respectively (p=0.003).
We conclude that a surveillance program of vascular access dysfunction with percutaneous treatment as required provide excellent
patency rates in radial-cephalic fistulae. The great frequency of stenosis
recurrence specially on brachial-cephalic and PTFE
fistulae makes it necessary to reinforce the application of detection and early
treatment program.
Publication Only
[SU-FC079] Association of Clinic
Vascular Access Monitoring with Clinical Outcomes in Hemodialysis Patients: The
ESRD Quality (EQUAL) Study.
Laura C. Plantinga,
Bernard G. Jaar, Brad Astor, Nancy E. Fink, Joseph A.
Eustace, Michael J. Klag, Neil R. Powe.
Department of Medicine, Johns Hopkins University,
Baltimore, MD
Early identification of access complications may be associated with improved
patient outcomes. We examined whether patient outcomes were associated with
clinic-reported vascular access monitoring practices in an incident cohort of
363 HD patients treated at 64 clinics, starting in 1995. Analysis was
restricted to patients who survived at least 6 months and who had a first
permanent vascular access (arteriovenous fistula or graft) by 6 months after
the start of dialysis. The outcomes were access intervention, access failure,
6-month Kt/V, and all-cause hospitalization (average follow-up, 1.8 years) and
2-year mortality. Using Poisson regression (to obtain IRRs)
and Cox proportional hazards analyses (to obtain RHs),
we examined the association of monitoring practices with patient outcomes,
adjusting for potential confounders such as age, race, comorbidity,
labs at start of dialysis, and access vintage. After adjustment, patients who
received monitoring weekly or more often (52%) were more likely to have an
access intervention (RH=1.39, 95% CI, 1.05-1.83) than those who received
monitoring less than weekly. However, patients treated at clinics that reported
performing vascular access monitoring (80% of patients) were 31% less likely to
be hospitalized (IRR=0.69, 95% CI, 0.53-0.89) than those who received no
monitoring. Vascular access monitoring was not associated with access failure,
Kt/V, or mortality. Interestingly, patients treated at clinics that used
dynamic venous pressure for monitoring (26%) were more likely to have an access
intervention (RH=1.55, 95% CI, 1.24-1.95) and patients treated at clinics that
used urea recirculation (UR) for monitoring (33%) were less likely to be
hospitalized (IRR=0.56, 95% CI, 0.40-0.79) than patients not monitored with
these methods. Although more frequent monitoring is associated with greater
chance of access intervention, monitoring is not associated with access
failure. Also, these results suggest that vascular access monitoring in HD
clinics may be associated with fewer hospitalizations but not with mortality.
Funding Source: NHLBI
Sunday, October 31, 2004 , 5:00 PM
Free Communication:
Prevention and Correction of Access Problems (4:00 PM-6:00 PM)
[SU-FC078] Native Arteriovenous Fistula
Blood Flow Surveillance: A Randomised Controlled
Trial.
Kevan R. Polkinghorne, Kenneth K.P. Lau, Alan Saunder, Robert C. Atkins,
Peter G. Kerr. Nephrology, Monash Medical Centre, Melbourne, Victoria,
Australia; Radiology, Monash Medical Centre, Melbourne, Victoria, Australia;
Surgery, Monash Medical Centre, Melbourne, Victoria, Australia
Clinical practice guidelines recommend that the preferred method of stenosis
surveillance for native arteriovenous fistulae (AVF) is the monthly measurement
of AVF blood flow (Qa). However these recommendations are based
on observational studies without an adequate control group. Therefore we
conducted a randomised, prospective, double blind,
controlled trial to assess whether Qa surveillance
results in an increased detection of AVF stenosis over and above currently
accepted clinical criteria. 137 patients were randomly assigned to receive either continuing AVF surveillance using current clinical
criteria (control, usual treatment) or usual treatment plus AVF blood flow
surveillance (Qa surveillance group). The primary
outcome measure was the detection of a haemodynamically
significant AVF stenosis as determined by angiography. 67 and 68 patients were
assigned to the control and Qa surveillance groups
respectively. Patients in the Qa surveillance group
were twice as likely to have a stenosis detected compared to the control group
(HR 2.27, 95% C.I. 0.85 5.98,
p=0.09) although this did not reach statistical significance. There was also a
trend for a significant stenosis to be detected earlier in the Qa surveillance group (p=0.09, log rank test). Qa was significantly lower in AVF with a significant
stenosis compared to those which were normal (median Qa
760 versus 1390 ml/min, p=0.006). However, a reliance on the Qa results alone prior to angiography demonstrated at best
moderate prediction of stenosis (area under the receiver operating
characteristic curve 0.78, 95% C.I. 0.63 - 0.94). This study demonstrates that
the addition of AVF Qa monitoring to clinical
criteria doubled the detection of clinically significant stenosis. However the
reliance on blood flow criteria alone would miss a number of patients with a
significant stenosis. Therefore the addition of Qa
screening increases the detection of AVF stenosis but should not be the sole
method of surveillance.
Sunday, October 31, 2004 , 4:45 PM
Free Communication:
Prevention and Correction of Access Problems (4:00 PM-6:00 PM)
