EFFICACY OF THE NEW HAEMODIALYSIS TECHNIQUES: IN VITRO COMPARISON OF PRE- AND POST-DILUTIONAL HAEMODIAFILTRATION
Alain Ficheux and Angel Argilés. Montpellier. France
ARTERIOVENOUS ACCESS: INITIAL EVALUATION AND
Manuel Angoso de Guzman. Clinica Virgen del Consuelo. España
Session Start: Feb 29 22:00:15 2000
[22:00] (MJesus) ciao charlie
[22:01] (Charlie) ciao!
[22:01] (Jordi10) ciao Charlie
[22:01] (Jordi10) welcome back!
*** Jordi10 is now known as JBover
[22:07] (MJesus) hello Prof Ardiles
[22:08] (Burgos) Hello from Montpellier, Alain Ficheux and I are happy to koint the chat
[22:09] (Angoso_) Good night
[22:09] (Angoso_) Buena Noches
[22:10] *** Burgos is now known as angel
[22:11] (Angoso_) do we all speak spanish or are there any non -spanish speaker with us ?
[22:11] (angel) Para Manuel, podrias explicarme el test de Hallen un poco mejor?
[22:12] (Angoso_) Test de Allen :)
[22:12] (angel) Si eso el test de Allen
[22:13] (Angoso_) Consiste en comprobar la permeabilidad de la arteria Cubital y el arco palmar
[22:13] (Angoso_) de tal forma que le dices al paciente que apriete la mano
[22:13] (Angoso_) con ello deja de fluir la sangre por el arco palmar
[22:13] (Angoso_) y aprietas la arteria radial
[22:14] (Angoso_) con lo que, teóricamente, cuando abras la mano
[22:14] (Angoso_) si la arteria cubital es permeable
[22:14] (Angoso_) se volvera la mano de color rosado
[22:15] (Angoso_) luego lo repite con la arteria cubital para comprobar la radial
[22:15] (angel) y si no, se queda blanca?
[22:15] (Angoso_) si no existe flujo por una de las arterias no ocluídas, si
[22:16] (angel) Muchas gracias.
[22:16] (Angoso_) De nada
[22:16] (gerardo) es un test muy fiable?
[22:17] (Angoso_) Relatively sensible
[22:17] (Angoso_) And something that you should do with all your patients prior to sending him to the vascualr surgeon
[22:17] (Angoso_) ( my opinion )
[22:18] (angel) Since Carlos is not with us, could you tell me whether you use a dialysate K concentration of 2 or of 1.5 mM?
[22:20] (gerardo) Angoso
[22:20] (Angoso_) si
[22:20] (gerardo) que crees que le debemos dar
[22:20] (gerardo) más valor al test de reciculacion
[22:20] (Angoso_) de acuerdo
[22:21] (gerardo) o al aumento de presiones venosas?
[22:21] (Angoso_) when you are talkingabout grafts
[22:22] (Charlie) which reciculation test you think it's the best?
[22:23] (Angoso_) The best test is the one done with the trransonic
[22:23] (Angoso_) BUT it cost 10.000 $
[22:23] (angel) Is anyone doing haemodiafiltration?
[22:23] (Angoso_) alternative is to use the low flow method
[22:23] (Charlie) what about "low flow", "stop flow" and so on ?
[22:23] (Angoso_) as suggested in thre DOQI guidelines
[22:24] (Angoso_) We use the LOW flow method since is more reliable thjan the STOP method
[22:24] (Angoso_) avoiding teh effect of cardiopulminary recirculation
[22:25] (Angoso_) Angel we do use hemodialfiltration
[22:25] (Charlie) we too
[22:26] (angel) Are you using post- or pre-dilutional? and for how long have you been doing it?
[22:27] (Charlie) usually post, but, in case of high Hematocrit, also pre or both (pre and post)
[22:27] (Angoso_) Usually post for last 5 years
[22:28] (angel) Charlie, have you had many patients being exclusively treated with pre-dilutional for very long?
[22:29] (Angoso_) I will like to introduce mu shy coworker Dra Vazquez = mv
[22:29] (MJesus) dra, vazquez, wellcome!
[22:30] (angel) good nitght Dra Vazquez
[22:31] (Angoso_) it isa pleasure to introduce Dr Argiles
[22:31] (Angoso_) Dr Argiles that is sorry
[22:32] (speaker) Efficacy of the new haemodialysis
techniques: In vitro comparison of pre- and post-dilutional
[22:32] (speaker) Alain Ficheux and Àngel Argilés
[22:32] *** speaker is now known as Argiles_
[22:32] (Argiles_) Introduction
[22:32] (Argiles_) New renal replacement techniques aim to improve the clearances of small as well as large molecules. It is accepted that diffusive methods mostly influence low molecular
[22:32] (Argiles_) weight solutes whereas high molecular weight components are preferentially driven
[22:33] (Argiles_) by convective forces. Haemodiafiltration is one of the most efficient dialysis
[22:33] (Argiles_) techniques presently available, which incorporates both diffusive and convective
[22:33] (Argiles_) forces (1).
[22:33] (Argiles_) In post-dilutional haemodiafiltration the removed plasma is partially replaced after the
[22:33] (Argiles_) haemodialyser, just before returning the blood to the patient. However, increasing
[22:33] (Argiles_) ultrafiltration rate results in increased concentration of the retained elements - mainly
[22:33] (Argiles_) the cellular component of blood - within the dialyser. This haemoconcentration with its
[22:33] (Argiles_) associated increase in viscosity as blood passess through the dialyser may become
[22:33] (Argiles_) a limiting factor of the amount of convectional mass transfer that may be achieved
[22:33] (Argiles_) with post-dilutional techniques. Pre-dilutional haemodiafiltration and haemofiltration,
[22:33] (Argiles_) which re-inject the replacement fluid before the dialyser obviate the
[22:33] (Argiles_) haemoconcentration phenomenon and extend the range of blood flow and
[22:34] (Argiles_) ultrafiltration rate that are allowed in vivo (2).
[22:34] (Argiles_) However, the precise benefits of the convective flow used in on-line
[22:34] (Argiles_) haemodiafiltration, and particularly the differences in efficiency between pre and
[22:34] (Argiles_) post-dilutional haemodiafiltration have not been well quantified.
[22:34] (Argiles_) The aim of this study was to evaluate the final clearances of small solutes in
[22:34] (Argiles_) haemodiafiltration and compare pre- versus post-dilutional haemodiafiltration. To
[22:34] (Argiles_) precisely evaluate total clearances in both haemodiafiltration settings we built an " in
[22:34] (Argiles_) vitro " system, which enabled us to easily modify QB, QD, convection volume, as well
[22:34] (Argiles_) as the infusion site (pre or post-dilutional). This system has been previously validated
[22:34] (Argiles_) and described elsewhere (3).
[22:35] (Argiles_) Materials and Methods
[22:35] (Argiles_) Total ion clearance was used as a surrogate of urea clearance to evaluate the
[22:35] (Argiles_) efficacy of dialysis techniques based on previous studies (4,5). In the present study
[22:35] (Argiles_) we determined total ion clearance in the absence of net ultrafiltration according to the
[22:35] (Argiles_) following formula:
[22:35] (Argiles_) Clearance = Dialysance = QD x ( CDi - CDo )/ CDi
[22:35] (Argiles_) C = concentration of total ion
[22:35] (Argiles_) QD = total dialysate flow produced by the system
[22:35] (Argiles_) (QD= QDi (at dialysate inlet) + Qinf (infusion flow))
[22:35] (Argiles_) Di = dialysate inlet
[22:35] (Argiles_) Do = dialysate outlet
[22:36] (Argiles_) The measured conductivity, was used to obtain the concentration value following our
[22:36] (Argiles_) experimental data.
[22:36] (Argiles_) RC= 0.000381*S^2 + 0.066217*S - 0.020226
[22:36] (Argiles_) RC = Relative Concentration
[22:36] (Argiles_) S = Conductivity (mS/cm)
[22:36] (Argiles_) The in vitro system is described in Figure 1. A dialysis monitor with a volumetric
[22:36] (Argiles_) ultrafiltration controller was used. Therefore, changing the flow setting of the infusion
[22:36] (Argiles_) pump could easily and precisely modify the convection volume per time unit.
[22:36] (Argiles_) Accordingly, convective flow was varied in this study by modifying infusion flow rate.
[22:36] (Argiles_) Degassed, reverse osmosis, warmed water was used for the blood compartment fluid. Precise
[22:36] (Argiles_) QD and QB were checked by collecting the volumes over a time period before and at
[22:37] (Argiles_) the end of each series of measurements. Three repeats were performed for each
[22:37] (Argiles_) control point.
[22:37] (Argiles_) Study protocol
[22:37] (Argiles_) A cellulose triacetate dialyser of 1.70 m² was used in this study, (FB-170 U, Nipro,
[22:37] (Argiles_) NISSHO Corporation, Osaka, Japan). Three different dialysers were used and three
[22:37] (Argiles_) repeats were performed in each separate experiment for every data point of the
[22:37] (Argiles_) study. The mean value of the separate experiments was used for analysis.
[22:37] (Argiles_) The influence of dialysate and blood flows was measured both as an internal control
[22:37] (Argiles_) of the in vitro setting and to evaluate the magnitude of the influence of these
[22:37] (Argiles_) parameters on the final clearance. The blood flows tested ranged from 250 to 450
[22:37] (Argiles_) ml/min in order to mimic the in vivo dialysis. The dialysate flows assessed ranged
[22:38] (Argiles_) from 420 to 970 ml/min.
[22:38] (Argiles_) Infusion site. The main point of the study was the comparison between pre- and
[22:38] (Argiles_) post-diafiltration. The precise infusion sites for both techniques are depicted in
[22:38] (Argiles_) dotted lines in Fig 1.
[22:38] (Argiles_) Statistics. Values are given as the mean ± standard error of the mean.
[22:38] (Argiles_) Results
[22:38] (Argiles_) QB influence on total ion clearance. Fig 2-a depicts the influence of the increase
[22:38] (Argiles_) in QB from 250 to 450 ml/min, both with QD=620 ml/min and QD=970 ml/min on total
[22:38] (Argiles_) ion clearance. An increase on QB resulted in an increase in total ion clearance from
[22:38] (Argiles_) 228± 1 to 336± 1 ml/min with a QD = 620 ml/min. When QD was increased to 970
[22:38] (Argiles_) ml/min the final clearance was similar to that observed with QD = 620 ml/min for low
[22:39] (Argiles_) QB levels (250 ml/min) and differed while increasing QB (Fig 2-a).
[22:39] (Argiles_) QD
[22:39] (Argiles_) influence on total ion clearance. Figure 2-b depicts the experiments performed
[22:39] (Argiles_) with a range of QD from 420 to 970 ml/min. For a fixed QB = 350 ml/min the total ion
[22:39] (Argiles_) clearance increased from 258±5 to 301±1 ml/min (Fig 2-b).
[22:39] (Argiles_) Infusion site study. Isolated dialysis as well as 100 ml/min of added convection in
[22:39] (Argiles_) pre- and post-dilutional haemodiafiltration for a fixed QB=350 ml/min with total
[22:39] (Argiles_) dialysate fluid (QD) production maintained at either 620 or 970 ml/min are presented
[22:39] (Argiles_) in figure 3. Infusion of the replacement fluid in post-dilutional diafiltration resulted in a significant increase in total ion clearance. The opposite was observed when the
[22:39] (Argiles_) replacement fluid was injected before the dialyser in pre-dilutional diafiltration.
[22:39] (Argiles_) Infusate volume study. We assessed a range of infusion rate from 0 (isolated
[22:40] (Argiles_) dialysis) to 200 ml/min (reasonable maximum used in clinical practice). With
[22:40] (Argiles_) post-dilutional haemodiafiltration we observed a linear increase in total ion
[22:40] (Argiles_) clearance, whilst with pre-dilutional haemodiafiltration we obtained a linear decrease
[22:40] (Argiles_) in total ion clearance (Figure 4-a).
[22:40] (Argiles_) Comparison of dialysis efficacy using 620 and 970 ml/min of total dialysate
[22:40] (Argiles_) production flow both with isolated dialysis and post-dilutional diafiltration.
[22:40] (Argiles_) The results are depicted in fig 4-b. Again, total ion clearances were significantly
[22:40] (Argiles_) increased with 100 ml/min post-dilutional infusion both at 620 and 970 ml/min of QD.
[22:40] (Argiles_) When comparing the absolute values of the different experiments it can be observed
[22:40] (Argiles_) that post-dilutional haemodiafiltration with a total QD production of 620 results in a
[22:40] (Argiles_) higher total ion clearance than isolated dialysis with a total QD of 970 ml/min. The
[22:40] (Argiles_) addition of post-dilutional infusion in the higher QD resulted in a further increase in
[22:41] (Argiles_) total ion clearance, this being the most efficient setting of those we assessed.
[22:41] (Argiles_) Discussion
[22:41] (Argiles_) Following the policies of renal replacement therapy applied in most countries, it is
[22:41] (Argiles_) becoming more and more important to evaluate the cost-effectiveness of different
[22:41] (Argiles_) treatments. This fully applies for haemodiafiltration since it is an expensive technique
[22:41] (Argiles_) that is supposed to improve dialysis efficacy. On-line haemodiafiltration was
[22:41] (Argiles_) conceived to limit the spending increase associated to the use of manufactured
[22:41] (Argiles_) infusion fluids for haemodiafiltration and to allow unlimited convection volumes (6).
[22:41] (Argiles_) Besides to minimising the added costs inherent to haemodiafiltration, it is therefore
[22:41] (Argiles_) important to properly evaluate the efficacy of this system.
[22:42] (Argiles_) The present study clearly shows that post-dilutional haemodiafiltration results in a
[22:42] (Argiles_) significant increase in the clearance of small molecular weight components and that
[22:42] (Argiles_) this increase is proportional to the amount of convection added. Interestingly, it also
[22:42] (Argiles_) shows that pre-dilutional haemodiafiltratio n follows an opposite tendency. Increasing
[22:42] (Argiles_) convection, with its associated increase in the infusion of the replacement fluid
[22:42] (Argiles_) before the dialyser, decreases also proportionally, the efficacy in clearing small
[22:42] (Argiles_) molecular weight solutes.
[22:42] (Argiles_) While the increased clearances associated to post-dilutional haemodiafiltration are
[22:42] (Argiles_) well known and taken profit of in clinic, the information concerning the modifications
[22:42] (Argiles_) in the efficacy of pre-dilutional haemodiafiltration is scant. Only two studies have
[22:42] (Argiles_) previously reported that pre-dilutional haemodiafiltration may actually be less
[22:43] (Argiles_) effective than simple haemodialysis. Ahrenholz et al (7) assessed the clearance of a
[22:43] (Argiles_) variety of substances with different molecular weight in a limited number of
[22:43] (Argiles_) convection settings in pre-dilutional haemodiafiltration and found that total clearance
[22:43] (Argiles_) tended to decrease in pre-dilutional haemodiafiltration (7). In our studies (3 and the
[22:43] (Argiles_) present data), we assessed an extended convection range and found that the
[22:43] (Argiles_) decrease in total clearance seemed to have a linear distribution (3). Very recently,
[22:43] (Argiles_) we have confirmed the linearity of this distribution and provided the simplified
[22:43] (Argiles_) formula to calculate total clearance of small molecular weight solutes in
[22:43] (Argiles_) haemodiafiltration (8). All these studies confirm that in on-line pre-dilutional
[22:43] (Argiles_) haemodiafiltration, the more we increase convection, the less we will be clearing
[22:43] (Argiles_) small molecular weight solutes (3,7,8).
[22:44] (Argiles_) In our institution we have been using on-line post-dilutional haemodiafiltration since
[22:44] (Argiles_) 1990 with very high removal of both small as well as high mol wt compounds (9). With
[22:44] (Argiles_) the flow rates employed (typically 100 ml/min) the average measured Kt/V urea is 1.7
[22:44] (Argiles_) ± 0.2 and as we have reported previously the reduction of serum b2-microglobulin is
[22:44] (Argiles_) over 60% for a haemodiafiltration session (10). However, we are limited in the
[22:44] (Argiles_) convective volume by the induced haemoconcentration, particularly in those patients
[22:44] (Argiles_) with high haematocrite level. Thus, pre-dilutional haemodiafiltration was considered,
[22:44] (Argiles_) but rejected on the grounds of the data presented in this study.
[22:44] (Argiles_) Taking together the results of the present experiments, the cost-effective comparison
[22:44] (Argiles_) of the different haemodialysis settings shows that on-line post-dilutional diafiltration
[22:44] (Argiles_) results in a superior performance. It is noteworthy, that the increase in dialyser
[22:45] (Argiles_) clearance induced by 100ml/min of convection, for a total diaysate production of 620
[22:45] (Argiles_) ml/min is ~8 % (for 350 ml/min of QB). This value is significantly higher than that
[22:45] (Argiles_) obtained with a 50% increase in dialysate flows and normal dialysis (970 ml/min of
[22:45] (Argiles_) total dialysate produced and spent). Therefore, for a better efficiency, the savings of
[22:45] (Argiles_) post-dilutional haemodiafiltration are evident.
[22:45] (Argiles_) The end
[22:45] *** Argiles_ is now known as Speaker
[22:45] (Angoso) EXCELLENT JOB
[22:46] (gerardo) excelente trabajo angel
[22:46] (gerardo) gracias
[22:46] (angel) thank you o gracias. Alain and miself will be hapy to comment anything on that
[22:46] (Angoso) Perhaps it was said in the discussion but why should and increase in convection decrease low molecular weight TRANSFER ?
[22:47] (MJesus) alain is here ?
[22:47] (angel) yes we are sharing our PC
[22:47] (Angoso) AND did you mention the type of dialyzer used ?
[22:47] (MJesus) hello alain, congratulations!
[22:48] (angel) The decrease must be due to the dilution and decrease in the concentration gradient
[22:48] (angel) Angoso, we used 3 different dialysers (Polysulfone and TCA)
[22:49] (Angoso) thx u
[22:49] (Angoso) for the answer
[22:50] (gerardo) el aclaramiento de medias moleculas muestra diferencias pre y pos dilucional
[22:50] (Angoso) Hve you notice more hemodynamic stability in those patients with a low ejection fraction less say EF < 30 %
[22:51] (angel) Ahrenholz lo estudio y demostro que en predilucion podia aumentar el aclaramiento ligeramente.
[22:51] (Angoso) WITH A DECREASE need of either hypertonic or hemostarch fluid replacement ??
[22:53] (angel) Angoso, we reported a few years ago that in patients with cardiovascular disease, HDF was beneficial for the bp stability
[22:53] (angel) The replacement fluid we have always used is the ultrafiltered dialysate (on-line HD)
[22:53] (gerardo) Haceis de rutina esta tecnica o simplemente para estudios?
[22:54] (Charlie) do you use the Gambro system?
[22:54] (angel) De rutina
[22:54] (angel) Charlie, we are presently using the AK200. We used to use Fresenius 2008C for the first 8 years
[22:55] (perico) could you explain some details about the cost-effectiveness of the hemodiafiltration with such high QD rates ?
[22:56] (angel) Our study demonstrated that is better cost-effective to produce 620 ml/min and use post-dilutional HDF tahn produce 970 and use only HD
[22:56] (angel) Some investigators in USA proposed to use very high QD
[22:58] (Angoso) one issue may be tthe increase in cytokine production using on line susbtitute
[22:58] (Charlie) is reuse allowed in Spain, and in France?
[22:58] (angel) However, at this level of QD we are already close to the plateau zone and the increase in clearance is not linear (while the expenses in producing dialysate, still increase)
[22:58] (angel) Charlie, re-use has been banded in France within the last 2 years
[22:59] (Angoso) Spain has never alloud reuse
[23:00] (angel) Angoso, I think that re-use has exited in Spain, though!!
[23:01] (angel) It was the comon practice when I started dialysis in the late seventies and early eighties
[23:01] (gerardo) en España por los años 72 se rehusaban los dializadores de bobina
[23:01] (Charlie) in Italy it was banned in 1975
[23:02] (Angoso) Well i have been working in Spain since 1992
[23:02] (gerardo) y se cebaban las lineas de sangre con la del paciente de una dialisis a otra
[23:04] (juanjose) no es muy cara esta técnica para utilizarla de rutina en todos los pacientes
[23:04] (Charlie) So, manifacturers MUST lower the cost of dialyzers at least!
[23:06] (angel) Juanjose, El sistema on-line se introdujo para diminuir los costos. Pero si que es mas cara que la dialsisis clasica. Well, as carlos Caramelo we thought that it was better to come to the lab to chat with you. It has been a pleasure. since there is no more questions we say good night and see you
[23:07] (pino) but in any case, it is too expensive, isnt it?
[23:07] (Angoso) Thank you ........ Angel
[23:07] (gerardo) gracias hasta otro momento
[23:07] (angel) goodnight. Keep going
[23:08] *** angel has quit IRC (Leaving)
[23:08] (Angoso_) ARTERIOVENOUS ACCESS: INITIAL EVALUATION AND
[23:08] (Angoso_) Manuel Angoso de Guzman
[23:08] (Angoso_) Clinica Virgen del Consuelo email@example.com vicom.es
[23:08] (Angoso_) INTRODUCTION
[23:09] (Angoso_) Most Nephrologists will rely on the surgeon decision on the type of dialysis
[23:09] (Angoso_) vascular access their ESRD patients are going to get and then complain if the
[23:09] (Angoso_) access is not functioning well or is placed in an anatomic position that is difficult
[23:09] (Angoso_) to access by the nurse or uncomfortable for the patient. Furthermore the outcome
[23:09] (Angoso_) of the vascular access is dependent of the surgeon interest in hemodialysis
[23:09] (Angoso_) access procedures.
[23:09] (Angoso_) The creation of an Arterio-Venous Fistula will cause arterial blood ( high speed
[23:09] (Angoso_) laminal flow ) to enter the venous low resistance system creating a laminar flow
[23:09] (Angoso_) with a continuous turbulence with a systolic peak at the site of the anastomosis
[23:09] (Angoso_) -the area with the highest pressure gradient. These ingredients, the increase in
[23:09] (Angoso_) pressure and flow in the venous side combined with the spectacular increase in
[23:09] (Angoso_) blood flow in the artery, are needed for successful AVF maturation Note: Blood
[23:09] (Angoso_) flow in a normal brachial artery is 85 ml/min and will increase by a factor of 5-10
[23:09] (Angoso_) after the fistula is open. The Arterial flow is dependent in a nonlinear relationship
[23:09] (Angoso_) with the cross sectional area of the fistula.
[23:10] (Angoso_) We will wait for at least 4 weeks beforet using the new access. During first two or 3
[23:10] (Angoso_) treatments we use a single needle hemodialysis with no heparin. The hand of the
[23:10] (Angoso_) patient is secure with a tape to avoid involuntary movement of the arm and trauma
[23:10] (Angoso_) to the vein wall by needle motion. Before accessing the AVF, the nurse does a
[23:10] (Angoso_) quick evaluation of the access. We use an ultrasound guided needle stick in those
[23:10] (Angoso_) accesses that are difficult to stick, i.e. a brachio-basilic vein or an obese patient.
[23:10] (Angoso_) Most stenosis will occur in the efferent vein near the arterial puncture. Stenosis
[23:10] (Angoso_) may occurs as early as 2 weeks after access placement and they are responsible
[23:11] (Angoso_) of early access failure 7 (see below) .
[23:11] (Angoso_) Access monitoring combined with early access intervention will increases
[23:11] (Angoso_) significantly cumulative access patency 20 . There are several methods to screen
[23:11] (Angoso_) AVF for signs of early dysfunctions. Most of these methods will detect functional
[23:11] (Angoso_) changes in the access rather than anatomical abnormalities.
[23:11] (Angoso_) Functional methods are used to evaluate access dysfunctions and are
[23:11] (Angoso_) appropriate for periodic access monitoring while angiography (gold Standard )
[23:11] (Angoso_) and ultrasounds are used for anatomical examination of the access. The AVF can
[23:11] (Angoso_) either fail to mature for needle cannulation or later become dysfunctional
[23:11] (Angoso_) FAILURE OF AVF TO MATURE
[23:12] (Angoso_) If after 8 weeks the AVF fails to mature, i.e. BFR < 350 ml/min and/or a recirculation
[23:12] (Angoso_) higher than 10% a fistulogram should be done . The ultrasound, being very
[23:12] (Angoso_) sensitive and specific for detecting graft dysfunctions, is less reliable for the
[23:12] (Angoso_) evaluation of AVF anatomy.(see below)
[23:12] (Angoso_) Beathard et al have recently published their results on salvage of early
[23:12] (Angoso_) nonfunctional fistulas. Out of 63 patients with inadequate AVF development 74.7
[23:12] (Angoso_) % had their access patent after 1 year using the following techniques after
[23:12] (Angoso_) angiography in a stepwise fashion: percutaneous angioplasty, accessory vein
[23:12] (Angoso_) ligation, medial vein ligation and mainstream banding 21. Therefore most AVF that
[23:12] (Angoso_) failed to developed should be evaluated since most early AV access dysfunctions
[23:12] (Angoso_) can be rescued and become functional sparing the patient the frustration of
[23:12] (Angoso_) having to go through the creation of another access and the placement of a central vein line.
[23:12] (Angoso_) Although underused and very dependent on the experience and interest of the
[23:13] (Angoso_) examiner, a thorough examination of the AVF ( which takes 3-5 min ) will provide
[23:13] (Angoso_) much information about access function . At examination there are different clues
[23:13] (Angoso_) that can give an idea of the anatomical abnormalities present in the fistula. (See Table 4)
[23:13] (Angoso_) The goal , nevertheless , is to be able to pick early those accesses that are going
[23:13] (Angoso_) to fail so an elective solution can be offer avoiding the risk of a long standing
[23:13] (Angoso_) central line,the loss of a very valuable venous area and the need to create another
[23:13] (Angoso_) access in a group of patients that cannot afford it.
[23:13] (Angoso_) VENOUS PRESSURE 22
[23:13] (Angoso_) Useless for monitoring AVF 23 since, as the intravenous pressure rises, blood flow
[23:14] (Angoso_) is diverted through vein collaterals preventing an increase in venous
[23:14] (Angoso_) pressure.Once there is a suspicion of venous stenosis the patient should
[23:14] (Angoso_) probably have a fistulogram to assess anatomy.
[23:14] (Angoso_) RECIRCULATION
[23:14] (Angoso_) Access recirculation (RC) develops when dialyzed blood returning the patient
[23:14] (Angoso_) through the venous side reenters the extracorporeal circuit through the arterial
[23:14] (Angoso_) needle. Recirculation decreases significantly the amount of HD delivered and is a
[23:14] (Angoso_) marker for access stenosis. Recirculation occurs when the AVF blood flow rate
[23:14] (Angoso_) (average AVF blood flow 1000 ml /min) 24 is less than the blood pump. There are several systems to measure RC
[23:15] (Angoso_) COMPLICATIONS
[23:15] (Angoso_) CARDIAC FAILURE ( High Output) 29 39
[23:15] (Angoso_) High output cardiac failure is a rare complication occurring more frequently in
[23:15] (Angoso_) patients with a braquiocephalic or transposed basilic vein access. The treatment
[23:15] (Angoso_) is either banding or ligation of the access. Banding can be complicated with
[23:15] (Angoso_) venous hypertension and the development of an upper arm edema.
[23:15] (Angoso_) NEUROPATHY
[23:15] (Angoso_) This complication ,Ischemic monomelic neuropathy, is seen in patients with
[23:15] (Angoso_) peripheral vascular disease -most frequently in diabetics.The patient developed a
[23:15] (Angoso_) severe excruciating pain of the involved extremity with wrist drop suggestive of
[23:16] (Angoso_) radial injury at the levels of the elbow secondary to peripheral ischemic
[23:16] (Angoso_) neuropathy 40-42 .Treatment consist in fistula ligation.
[23:16] (Angoso_) VENOUS HYPERTENSION 43-45
[23:16] (Angoso_) The hand distal to the access is swollen with thickening and hyperpigmentation of
[23:16] (Angoso_) the skin .In extreme cases there is distal extremities ulceration or the development
[23:16] (Angoso_) of a kaposi -like sarcoma46.The use of central Vein lines may lead to central vein
[23:16] (Angoso_) stenosis or thrombosis with the development of massive upper extremity edema
[23:16] (Angoso_) after access placement .
[23:16] (Angoso_) STEEL SYNDROME 47,4849,50
[23:16] (Angoso_) Some degree of retrograde flow occurs in almost every AVF being higher in
[23:17] (Angoso_) side-to side anastomosis and in braquiocephalic fistula .For example in a normal
[23:17] (Angoso_) radiocephalic fistula 20 % of blood will come from the distal artery .(Anderson )
[23:17] (pagoa) hola
[23:17] (Angoso_) The steel syndrome occurs due to a retrograde flow from the distal artery of the
[23:17] (Angoso_) anastomosis to the low resistance venous system causing the blood flow tol go
[23:17] (Angoso_) from the ulnar to the radial artery through the palmar arch with hypoperfusion of
[23:17] (Angoso_) the palm and forefingers .The incidence is higher in the artherosclerotic and
[23:17] (Angoso_) diabetic patients . The clinical presentation is a painful, cold and clammy hand that
[23:17] (Angoso_) gets worst on hemodialysisIt can lead to acral gangrene and finger amputation .
[23:17] (Angoso_) To prevent this problem in high risk patient distal radial artery ligation can be
[23:17] (Angoso_) performed . End-to-end anastomosis is complicated by technical problems like
[23:17] (Angoso_) vessel rotation during the anastomosis or higher percentage of stenosis which
[23:17] (Angoso_) will increse the risk of poor blood flow rate and early thrombosis .
[23:18] (Angoso_) THE END
[23:18] (gerardo) gracias
[23:18] (gerardo) una pregunta
[23:18] (Angoso) I will be happy to answer any question
[23:18] (Angoso) gerardo
[23:18] (gerardo) que diferencia debe existir
[23:19] (gerardo) entre un eco normal y otro con bloquo de la fistula
[23:19] (gerardo) para indicar ligadura por insuficiencia cardiaca
[23:20] (gerardo) eco cardiaco
[23:20] (Angoso) La ecografia normal podras ver con en el corte longitudinal una disminucion de calibre
[23:20] (Angoso) Cuando bloqueas el acceso vascular
[23:20] (Angoso) se produce una disminucion importante de la frecuencia cardiaca
[23:21] (Angoso) asociada con una disminucion de la presion intraventricular
[23:21] (Angoso) y del diametro de la cavidad del ventriculo izq
[23:21] (gerardo) si pero hay algun cifra de corte?
[23:21] (gerardo) en las diferencias?
[23:22] (Angoso) Creo que en los trabajos publicados la disminucion de la frecuencoia cardiaca espopr encima de 15 latidos /min
[23:23] (gerardo) vale gracias
[23:23] (gerardo) otra cosa
[23:23] (gerardo) en las estenosis de nativas actuación quirúrgica o sten?
[23:24] (gerardo) teniendo en cuenta que el sten invalida una zona
[23:24] (Angoso) Creo que NO SE DEBERIA USAR el stent en este tipo de lesiones
[23:24] (Charlie) subclavian catheters are well known to produce central stenosis:
[23:25] (Charlie) are you sure that Jugular ones don't?
[23:25] (Angoso) El stent va inducir una hiperplasia a nivel endotelial
[23:26] (gerardo) que experiencias tienes con los cateteres permanentes?
[23:26] (Angoso) Jugular catheter do produces stenosis (around 10-15% ) most commonly in the left yugular vein
[23:26] (Angoso) Tenemos actualmente 4 pacientes. Los colocamos nosotros y usamos el tesio
[23:27] (gerardo) si igual que nosotros
[23:27] (gerardo) el permccath lo pusimos pero nos da un poco de respeto
[23:28] (gerardo) que tiempo os duran?
[23:28] (Angoso) Hemos tenido pacientes con cateteres puestos durante 3 años
[23:29] (Angoso) Y nuestra tasa de infecciones es practicamente 0
[23:29] (gerardo) que poniais uroquinasa?
[23:29] (gerardo) o uroquinasa y hepariana o tpa?
[23:29] (Angoso) Usamos uroquinasa con heparina ( Schon )
[23:30] (Angoso) Hay 2 casos publicados de transmision de hepatits C con urokinasa
[23:30] (Angoso) con lo que en USA
[23:30] (Angoso) SE esta usando el TPI
[23:30] (Angoso) pero como sabras es muy cara
[23:30] (Angoso) aunque se puede congelar
[23:30] (Angoso) y disminuir los costes
[23:31] (gerardo) y ademas dien que se altera por el ph de la heparina no?
[23:31] (Angoso) Bueno Schon que lo ha estudiado no ha encontrado diferencias
[23:31] (Charlie) which pecentage of AVF versus prothesis and catheters?
[23:31] (Angoso) Charlie at the present time 65 AVF 4 PERMCATH 0 GRAFT
[23:32] (gerardo) Nosotros 4 cateres de tesio
[23:32] (gerardo) pero goretex bastantes
[23:33] (gerardo) no tenemos una cirugía rápida
[23:33] (MJesus) esto esta animadisimo.... pero ejem... miren los relojes
[23:34] (gerardo) 11,30 manolo un placer
[23:34] (MJesus) gracias manuel!!
[23:36] (gerardo) adios a todos
Session Closed: Feb 29 23:36:06 2000