Impact of Blood and Dialysate Flow and Surface on Performance of New Polysulfone Hemodialysis Dialyzers

2003 ◽  
Vol 26 (2) ◽  
pp. 113-120 ◽  
Author(s):  
S. Mandolfo ◽  
F. Malberti ◽  
E. Imbasciati ◽  
P. Cogliati ◽  
A. Gauly
Keyword(s):  
Blood Flow ◽  
Surface Area ◽  
Reduction Rate ◽  
Independent Effect ◽  
High Flux ◽  
Dialysate Flow ◽  
The Impact ◽  
Small Solute ◽  
Solute Clearance

Optimization of hemodialysis treatment parameters and the characteristics of the dialyzer are crucial for short- and long-term outcome of end stage renal disease patients. The new high-flux membrane Helixone® in the dialyzer of the FX series (Fresenius Medical Care, Germany) has interesting features, such as the relationship of membrane thickness and capillary diameter which increases middle molecule elimination by convection, as well as higher capillary packing and microondulation to improve the dialysate flow and distribution. Blood flow, dialysate flow and surface area are the main determinants of the performance of a dialyzer, however the impact of each parameter on small and middle molecule clearance in high flux dialysis has not been well explored. In order to find the best treatment condition for the new dialyzer series, we evaluated urea, creatinine, phosphate clearances and reduction rate of ß2-microglobulin in ten stable patients treated with different blood flows (effective Qb 280 and 360 ml/min), dialysate flow (Qd 300 or 500 ml/min) and dialyzer surfaces (1.4 and 2.2 m2, FX60 or FX100). KoA and Kt/V were also calculated. Blood flow, dialysate flow and surface area demonstrated a significant and independent effect on clearance of urea, creatinine and phosphate, as well as on Kt/V. Small solute clearance was stable over the treatment. In contrast to small solutes, reduction rate of ß2-microglobulin was related to increasing dialyzer surface only. The new dialyzer design of the FX series proves highly effective due to improved dialysate distribution and reduced diffusive resistance as shown by the small solute clearance. A high reduction rate of ß2-microglobulin is favored by improved fiber geometry and pore size distribution. These findings have potential long-term benefits for the patient

Arterial properties of the carotid and femoral artery in endurance-trained and paraplegic subjects

2000 ◽  
Vol 89 (5) ◽  
pp. 1956-1963 ◽  
Author(s):  
Arno Schmidt-Trucksäss ◽  
Andreas Schmid ◽  
Christian Brunner ◽  
Nicole Scherer ◽  
Guido Zäch ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Rate ◽  
Femoral Artery ◽  
Arterial Wall ◽  
Activity Level ◽  
Functional Adaptation ◽  
Local Blood Flow ◽  
Flow Changes ◽  
The Impact

In humans, the relationships of blood flow changes to structure, function, and shear rate of conducting arteries have not been thoroughly examined. Therefore, the purpose of this study was to investigate these parameters of the elastic-type, common carotid artery (CCA) and the muscular-type, common femoral artery (CFA) in long-term highly active and extremely inactive individuals, assuming that the impact of activity-induced blood flow changes on conduit arteries, if any, should be seen in these subjects. We examined 21 highly endurance-trained athletes (A), 10 paraplegic subjects (P), and 20 sedentary subjects (S) by means of noninvasive ultrasound. As a result, the CFA diameter and compliance were highest in A (9.7 ± 0.81 mm; 1.84 ± 0.54 mm2/kPa) and lowest in P (5.9 ± 0.7 mm; 0.54 ± 0.27 mm2/kPa) compared with S (8.3 ± 1.0 mm; 0.92 ± 0.48 mm2/kPa) with P < 0.01 among the groups. Both parameters correlated with each other ( r = 0.62; P < 0.01). Compared with A (378 ± 84 s−1; 37 ± 15 s−1) and S (356 ± 113 s−1; 36 ± 20 s−1), the peak and mean shear rates of the CFA were almost or more than doubled in P (588 ± 120 s−1; 89 ± 26 s−1). In the CCA, only the compliance and peak shear rate showed significant differences among the groups (A: 1.28 ± 0.47 mm2/kPa, 660 ± 138 s−1; S: 1.04 ± 0.27 mm2/kPa, 588 ± 109 s−1; P: 0.65 ± 0.22 mm2/kPa, 490 ± 149 s−1; P < 0.05). In conclusion, the results suggest a structural and functional adaptation in the CFA and a predominantly functional adaptation of the arterial wall properties to differences in the physical activity level and associated exercise-induced blood flow changes in the CCA. The results for humans confirm those from animal experiments. Similar shear rate values of S and P in the CFA support the hypothesis of constant shear stress regulation due to local blood flow changes in humans. On the other hand, the increased shear rate in the CFA in P indicates an at least partially nonphysiological response of the arterial wall in long-term chronic sympathectomy due to a change in local blood flow.

Persistent Symptomatic Intra-Abdominal Collection after Catheter Removal for Pd-Related Peritonitis

2011 ◽  
Vol 31 (1) ◽  
pp. 34-38 ◽  
Author(s):  
Cheuk-Chun Szeto ◽  
Bonnie Ching-Ha Kwan ◽  
Kai-Ming Chow ◽  
Wing-Fai Pang ◽  
Vickie Wai-Ki Kwong ◽  
...  
Keyword(s):  
Percutaneous Drainage ◽  
Direct Conversion ◽  
Catheter Removal ◽  
Peritoneal Catheter ◽  
Percutaneous Aspiration ◽  
Severe Peritonitis ◽  
Culture Negative ◽  
Small Solute ◽  
Solute Clearance

BackgroundPeritoneal dialysis (PD) patients with severe peritonitis require catheter removal. It is often assumed that this approach, together with antibiotics, would eradicate the infection; however, some patients continue to have problems despite catheter removal.MethodWe reviewed 30 consecutive PD patients in our center from 1997 to 2008 with recurrent loculated peritoneal collection after catheter removal for severe peritonitis.ResultsOf the 1928 episodes of peritonitis that occurred in 702 patients during the study period, 11.1% required catheter removal and 1.6% developed recurrent peritoneal collection that required percutaneous drainage. Median time to diagnosis of intra-abdominal collection was 12 days after catheter removal (interquartile range 7 – 61 days). In 25 patients (83.3%), aspirate of the abdominal collection was culture negative. In 17 patients (56.7%), the abdominal collection was recurrent and required repeated percutaneous aspiration. Only 3 patients had successful reinsertion of the peritoneal catheter but all had reduced small solute clearance after returning to PD.ConclusionA small but not negligible proportion of patients with PD-related peritonitis develop recurrent intra-abdominal collection that requires percutaneous drainage after catheter removal. The chance of a successful return to PD is very low in this group of patients. Direct conversion to long-term hemodialysis may avoid unnecessary attempts at peritoneal catheter reinsertion.

scholarly journals Acute and chronic stage adaptations of vascular architecture and cerebral blood flow in a mouse model of TBI

2018 ◽  
Author(s):  
Joe Steinman ◽  
Lindsay S. Cahill ◽  
Margaret M. Koletar ◽  
Bojana Stefanovic ◽  
John G. Sled
Keyword(s):  
Blood Flow ◽  
Ex Vivo ◽  
Vessel Density ◽  
Vascular Architecture ◽  
Two Photon ◽  
Brain Vasculature ◽  
The Impact ◽  
The Brain ◽  
Time Point

AbstractThe 3D organization of cerebral blood vessels determines the overall capacity of the cerebral circulation to meet the metabolic requirements of the brain. This study used Arterial Spin Labeling (ASL) MRI with a hypercapnic challenge and ex vivo Serial Two-Photon Tomography (STPT) to examine the relationship between blood flow and 3D microvascular structure following traumatic brain injury (TBI) in a mouse. Mice were exposed to a controlled cortical impact TBI and allowed to recover for either 1 day or 4 weeks. At each time point, ASL MRI was performed to quantify cerebral perfusion and the brain vasculature was imaged in 3D with STPT. Registration of ASL to STPT enabled flow changes to be related to the underlying microvascular structure in each ASL voxel. Hypoperfusion under rest and hypercapnia was observed both 1 day and 4 weeks post-TBI. Vessel density and vascular volume were reduced 1 day post-TBI, recovering by 4 weeks; however, the reorganized vasculature at the latter time point possessed an abnormal radial pattern. Our findings demonstrate functionally significant long-term changes in the vascular architecture following injury and illustrate why metrics beyond traditional measures of vessel density are required to understand the impact of vascular structure on function.

Ultrasound Measurements of Intracranial Structures in Growth-Restricted Neonates with Fetal Blood Flow Redistribution: A Pilot Observational Study

Neonatology ◽  
2020 ◽  
Vol 117 (4) ◽  
pp. 446-452
Author(s):  
Pramod Pharande ◽  
Mohan Krishnamurthy ◽  
Gillian Whiteley ◽  
Arun Sasi ◽  
Atul Malhotra
Keyword(s):  
Blood Flow ◽  
Observational Study ◽  
Prospective Observational Study ◽  
Brain Structures ◽  
Cranial Ultrasound ◽  
Fetal Blood ◽  
The Impact ◽  
The Brain ◽  
Blood Flow Redistribution

<b><i>Background:</i></b> Fetal growth restriction (FGR) is associated with neonatal and long-term neuro-morbidity. Preferential redistribution of blood flow to the brain is a common antenatal adaptation in FGR. The impact of this “brain sparing,” which may signify severity of FGR, on the growth of brain structures has not been studied. <b><i>Aim:</i></b> To compare corpus callosum (CC), cerebellar, and ventricular measurements of FGR neonates with evidence of fetal blood flow redistribution with those of gestation-matched appropriately grown (AGA) neonates. <b><i>Methods:</i></b> This was a pilot, prospective observational study conducted at a tertiary level neonatal unit in Melbourne, Australia. Cranial ultrasound was done between days 1 and 3 of life in FGR and AGA neonates. <b><i>Results:</i></b> Cranial ultrasound on 20 FGR, gestation (mean ± SD) 31.4 ± 3.1 weeks, weight 1,205 ± 463 g, and 20 AGA neonates, 31.1 ± 3.0 weeks, 1,668 ± 490 g, was performed. CC length was significantly decreased in FGR neonates as compared to AGA neonates (35.28 ± 3.47 vs. 38.83 ± 4.05 mm, <i>p</i> = 0.0002). CC was significantly thinner at genu (3.36 ± 0.66 vs. 4.04 ± 0.83 mm, <i>p</i> = 0.007), body (1.97 ± 0.36 vs. 2.27 ± 0.39 mm, <i>p</i> = 0.02), and splenium (4.07 ± 0.76 vs. 4.72 ± 0.75 mm, <i>p</i> = 0.003) in FGR vs. AGA neonates. CC-fastigium length was also significantly decreased (39.65 ± 3.87 vs. 41.96 ± 4.50 mm, <i>p</i> = 0.04). Similarly, FGR neonates showed decreased transverse cerebellar diameter (36.15 ± 5.51 vs. 38.81 ± 7.21 mm, <i>p</i> = 0.02), but ventricular measurements were comparable. In multivariate analysis, these differences were evident independent of the birth weight. <b><i>Conclusions:</i></b>CC and cerebellar measurements are significantly smaller in FGR neonates with fetal blood flow redistribution, which warrants further study.

scholarly journals iPSC-derived MSC therapy induces immune tolerance and supports long-term graft survival in mouse orthotopic tracheal transplants

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Mohammad Afzal Khan ◽  
Fatimah Alanazi ◽  
Hala Abdalrahman Ahmed ◽  
Talal Shamma ◽  
Kilian Kelly ◽  
...  
Keyword(s):  
Stem Cells ◽  
Blood Flow ◽  
Stem Cell ◽  
Graft Survival ◽  
Immune Tolerance ◽  
Airway Epithelium ◽  
Microvascular Blood Flow ◽  
Human Mscs ◽  
The Impact

Abstract Background Lung transplantation is a life-saving surgical replacement of diseased lungs in patients with end-stage respiratory malfunctions. Despite remarkable short-term recovery, long-term lung survival continues to face several major challenges, including chronic rejection and severe toxic side effects due to global immunosuppression. Stem cell-based immunotherapy has been recognized as a crucial immunoregulatory regimen in various preclinical and clinical studies. Despite initial therapeutic outcomes, conventional stem cells face key limitations. The novel Cymerus™ manufacturing facilitates production of a virtually limitless supply of consistent human induced pluripotent stem cell (iPSC)-derived mesenchymal stem cells, which could play a key role in selective immunosuppression and graft repair during rejection. Methods Here, we demonstrated the impact of iPSC-derived human MSCs on the development of immune tolerance and long-term graft survival in mouse orthotopic airway allografts. BALB/c → C57BL/6 allografts were reconstituted with iPSC-derived MSCs (2 million/transplant/at d0), and allografts were examined for regulatory T cells (Tregs), oxygenation, microvascular blood flow, airway epithelium, and collagen deposition during rejection. Results We demonstrated that iPSC-derived MSC treatment leads to significant increases in hTSG-6 protein, followed by an upregulation of mouse Tregs and IL-5, IL-10, and IL-15 cytokines, which augments graft microvascular blood flow and oxygenation, and thereby maintained a healthy airway epithelium and prevented the subepithelial deposition of collagen at d90 post transplantation. Conclusions Collectively, these data confirmed that iPSC-derived MSC-mediated immunosuppression has potential to establish immune tolerance and rescue allograft from sustained hypoxic/ischemic phase, and subsequently limits long-term airway epithelial injury and collagen progression, which therapeutically warrant a study of Cymerus iPSC-derived MSCs as a potential management option for immunosuppression in transplant recipients.

scholarly journals The impact of intradialytic cycling on the removal of protein-bound uraemic toxins: A randomised cross-over study

2020 ◽  
pp. 039139882094988
Author(s):  
Celine De Vos ◽  
Laure Lemarcq ◽  
Annemieke Dhondt ◽  
Griet Glorieux ◽  
Wim Van Biesen ◽  
...  
Keyword(s):  
Serum Levels ◽  
Water Soluble ◽  
Dialysis Session ◽  
Small Water ◽  
Optimal Intensity ◽  
Intradialytic Exercise ◽  
The Impact ◽  
Kinetics Of ◽  
Small Solute ◽  
Solute Clearance

The evidence on impact of intradialytic exercise on the removal of urea, is conflictive. Impact of exercise on kinetics of serum levels of protein-bound uraemic toxins, known to exert toxicity and to have kinetics dissimilar of those of urea, has so far not been explored. Furthermore, if any effect, the most optimal intensity, time point and/or required duration of intradialytic exercise to maximise removal remain obscure. We therefore studied the impact of different intradialytic cycling schedules on the removal of protein-bound uraemic toxins during haemodialysis (HD). This randomised cross-over study included seven stable patients who were dialysed with an FX800 dialyser during three consecutive midweek HD sessions of 240 min: (A) without cycling; (B) cycling for 60 min between 60th and 120th minutes of dialysis; and (C) cycling for 60 min between 150th and 210th minutes, with the same cycling load as in session B. Blood and dialysate flows were respectively 300 and 500 mL/min. Blood was sampled from the blood inlet at different time points, and dialysate was partially collected (300 mL/h). Small water soluble solutes and protein-bound toxins were quantified and intradialytic reduction ratios (RR) and overall removal were calculated per solute. Total solute removal and reduction ratios were not different between the three test sessions, except for the reduction ratios RR60–120 and RR150–210 for potassium. In conclusion, we add evidence to the existing literature that, regardless of the timing within the dialysis session, intradialytic exercise has no impact on small solute clearance, and demonstrated also a lack of impact for protein-bound solutes.

scholarly journals Continuity of care and clinical outcomes in the community for people with severe mental illness

2018 ◽  
Vol 214 (5) ◽  
pp. 273-278 ◽  
Author(s):  
Alastair Macdonald ◽  
Dimitrios Adamis ◽  
Tom Craig ◽  
Robin Murray
Keyword(s):  
Clinical Outcomes ◽  
Continuity Of Care ◽  
Demographic Variables ◽  
Independent Effect ◽  
Long Term Conditions ◽  
Community Data ◽  
The Individual ◽  
The Impact ◽  
Generalised Estimating Equations

BackgroundHigh continuity of care is prized by users of mental health services and lauded in health policy. It is especially important in long-term conditions like schizophrenia. However, it is not routinely measured, and therefore not often evaluated when service reorganisations take place. In addition, the impact of continuity of care on clinical outcomes is unclear.AimsWe set out to examine continuity of care in people with schizophrenia, and to relate this to demographic variables and clinical outcomes.MethodPseudoanonymised community data from 5552 individuals with schizophrenia presenting over 11 years were examined for changes in continuity of care using the numbers of community teams caring for them and the Modified Modified Continuity Index (MMCI). These and demographic variables were related to clinical outcomes measured with the Health of the Nation Outcome Scales (HoNOS). Data were analysed using generalised estimating equations and multivariate marginal models.ResultsThere was a significant decline in MMCI and significant worsening of HoNOS total scores over 11 years. Higher (worse) HoNOS scores were significantly and independently related to older age, later years and both lower MMCI and more teams caring for the individual in each year. Most HoNOS scales contributed to the higher total scores.ConclusionsThere is evidence of declining continuity of care in this 11-year study of people with schizophrenia, and of an independent effect of this on worse clinical outcomes. We suggest that this is related to reorganisation of services.Declaration of interestNone.

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