| 1. |
- Hadimeri, Ursula
(författare)
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Factors affecting the physical characteristics of arterio-venous fistula in patients with renal failure
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background and PurposeA patent access is vital for a dialysis patient. The arterio-venous fistula (AVF), the most important access for haemodialysis (HD), is frequently affected by extensive complications such as stenosis and occlusions.Study I: To investigate whether the dimensions of AVFs used for performing haemodialysis were affected by the original disease.Study II: To investigate if the diameter of the distal radiocephalic fistula could influence left ventricular variables in stable haemodialysis patients.Study III: To investigate whether a single Far Infrared (FIR) light treatment could alter blood velocity, AVF diameter or inflammatory markers.Study IV: To evaluate in what extent the renal diagnosis and radiological interventions affected the dysfunction of AVF and results of percutaneous transluminal angioplasty (PTA).Materials and methodsStudy I: The lumen diameter of the AVF was studied by ultrasound in 19 patients with autosomal dominant polycystic kidney disease (ADPKD) and in 19 control patients. The monitoring was performed along the forearm part of the vein, the maximal diameter was measured. The diameters of the two needle insertion sites were also measured.Study II: Nineteen patients were investigated with echocardiography, using M-mode recordings and measurements in the 2D image. Ultrasound and doppler ultrasound were performed. Transsonic measurements were performed after the ultrasound investigation. Measurements of the diameter of the AVF were performed in four locations. Heart variables were analysed regarding left ventricular (LV) criteria.Study III: Thirty patients with native AVF in the forearm were included. Each patient was his/her own control. Ultrasound examinations of the AVF diameter and blood flow velocity were performed before and after a single Far Infrared light (FIR) treatment.Study IV: 522 radiological investigations and endovascular treatments between January 1, 2006 and December 31, 2014 were analysed in 174 patients, retrospectively. All investigations had been performed due to clinical suspicion of impaired AVF function. All stenoses were evaluated and the number, degree, length, location and relation to anastomosis were recorded. After PTA the remaining stenoses were evaluated again and complications were recorded.ResultsStudy I: The diameter of the AVF at the maximal site in patients with ADPKD was significantly wider than that for the control patients.Study II: A larger AVF mean and maximal diameter worsened left ventricular characteristics.Study III: A single FIR treatment resulted in a significant increase in blood velocity over the AV fistula from a mean of 2.1±1.0 m/s to 2.3±1.0 m/s. The diameter of the arterialized vein became wider, i.e. 0.72±0.02 to 0.80±0.02 cm. The increase in fistula blood velocity correlated positively with baseline serum-urate and the increase in venous diameter correlated positively with the baseline plasma orosomucoid concentration.Study IV: The degree of AVF stenosis before PTA correlated significantly with the degree of remaining stenosis after intervention. Arterial stenosis was significantly more frequent among patients with diabetic nephropathy and interstitial nephritis. A shorter life span between PTAs was related to diabetic nephropathy.ConclusionsStudy I: The receiving veins of AVF in patients with ADPKD have an abnormality that causes a greater than normal dilatation in response to the arterialization.Study II: The maximal diameter of the distal AVF seems to be a sensitive marker of LV impairment in stable haemodialysis patients.Study III: A single FIR treatment increased AVF blood velocity and vein diameter. Thus, one FIR treatment can help maturation of AVF in the early postoperative course.Study IV: Repeated PTA was performed significantly more often in patients with diabetic nephropathy. Clinically significant stenosis should be dilated as soon as possible. Occlusion of the AVF should be thrombolyzed and/or dilated when diagnosed.
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| 2. |
- Mahmood, Dana, 1965-
(författare)
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Lipoprotein lipase activity is reduced in dialysis patients. Studies on possible causal factors.
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cardiovascular disease is a major cause of mortality and morbidity in patients on chronic haemodialysis (HD). One main contributing factor is renal dyslipidaemia, characterized by an impaired catabolism of triglyceride (TG)-rich lipoproteins with accumulation of atherogenic remnant particles. The enzyme lipoprotein lipase (LPL) is a key molecule in the lipolysis of TG-rich lipoproteins into free fatty acids. The activity of LPL is reduced in HD-patients. This study was performed to elucidate various conditions and factors that may have an impact on LPL-related lipid metabolism.I. The functional pool of LPL is located at the vascular surface. The enzyme is released by heparin and low molecular weight heparins (LMWH) into the circulating blood and extracted and degraded by the liver. Heparin and LMWH are used for anticoagulation during HD to avoid clotting in the extracorporeal devices. This raises a concern that the LPL system may become exhausted by repeated administration of LMWH in patients on HD. In a randomized cross over designed study twenty patients on chronic HD were switched from a primed infusion of heparin to a single bolus of LMWH (tinzaparin). The LPL activity in blood was higher on HD with LMWH at 40 minutes but lower at 180 minutes compared to HD with heparin. These values did not change during the 6-month study period. With heparin a significant TG reduction was found at 40 minutes and a significantly higher TG value at 180 and 210 minutes than at start. TG was higher during the HD-session with tinzaparin than with heparin. Our data demonstrate that repeated HD with heparin or with LMWH does not exhaust the LPL-system in the long term but does disturb the LPL system and TG metabolism during every HD session. II. In this study HD patients were compared with patients on peritoneal dialysis (PD) in a case control fashion. PD patients showed the same reaction of the LPL system to LMWH as HD patients. This confirmed that both HD and PD patients had the same, reduced, heparin-releasable LPL pool. The main difference was that in PD patients the TG continued to be cleared effectively even at 180 minutes after the bolus of LMWH injection. This may be due to a slower removal of the released LPL by the liver in PD patients. III. In recent years, citrate (Citrasate) in the dialysate has been used in Sweden as a local anticoagulant for chronic HD. We performed a randomized cross over study that included 23 patients (16 men and 7 women) to investigate if citrate in the dialysate is safe and efficient enough as anticoagulant. The study showed that citrate anticoagulation eliminated the need of heparin or LMWH as anticoagulation for HD in half of the patients. However, individual optimization of doses of anticoagulants used together with citrate have to be made.IV. Recently angiopoietin-like proteins, ANGPTL3 and 4 have emerged as important modulators of lipid metabolism as potent inhibitors of LPL. Twenty-three patients on chronic HD and 23 healthy persons were included as case and controls to investigate the levels of these proteins in plasma of HD-patients and to evaluate if HD may alter these levels. The data showed that plasma levels of ANGPTL3 and 4 were increased in patients with kidney disease compared to controls. This may lead to inactivation of LPL. High flux-HD, but not low flux-HD, reduced the levels of ANGPTL4, while the levels of ANGPTL3 were not significantly influenced. On HD with local citrate as anticoagulant, no LPL activity was released into plasma during dialysis in contrast to the massive release of LPL with heparin (LMWH). Citrate HD was not associated with a significant drop in plasma TG at 40 minutes, while both HD with citrate and heparin resulted in significantly increased TG levels at 180 minutes compared to the start values.Conclusions: Citrate as a local anticoagulant during haemodialysis eliminates the need of heparin or LMWH in about half of the HD patients. Citrate does not induce release of LPL from its endothelial binding sites. We have shown that although HD with heparin causes release of the endothelial pool of LPL during each dialysis session, the basal pool is similarly low in PD patients that do not receive heparin. This indicates that the LPL pool is lowered as a consequence of the uraemia, per se. One explanation could be the increased levels of ANGPTL3 and 4. HD with high flux filters can temporarily lower the levels of ANGPTL4. Further studies are, however, needed to understand why LPL activity is low in patients with kidney disease.
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| 3. |
- Ramsauer, Bernd, 1954-
(författare)
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Glucose degradation products in patients on hemodialysis : interventional studies
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hemodialysis (HD) is the most frequently used treatment for end-stage renal disease. Despite all efforts to improve the outcomes, the mortality of patients on HD is still high, and this especially is related to cardiovascular diseases (CVD). Glucose degradation products accumulate in plasma and tissue as a result of oxidative stress in these patients. Such accumulation is strongly related to the risk of developing CVD. Tissue deposits of advanced glycation end products (AGE) can be easily assessed by a skin autofluorescence (SAF) technique. SAF is one of the strongest prognostic markers of mortality in HD patients. The aim of this thesis is to examine whether intervention on HD treatment can reduce the load of AGE of these patients.The aim of the first study was to investigate whether changes in SAF appear after a single HD session and if they might be related to changes in plasma AF. Skin and plasma AF (PAF) were measured before and after HD in 35 patients on maintenance HD therapy. Median dialysis time was 4 h (range 3-5.5). SAF was measured noninvasively with an AGE Reader, and plasma AF was measured before and after HD. The HD patients had on average a 65% higher SAF value than age-matched healthy persons (P < 0.001). PAF was reduced by 14% (P < 0.001), whereas SAF was not changed after a single HD treatment. No significant influence of the reduced PAF on SAF levels was found. This suggests that the measurement of SAF can be performed during the whole dialysis period and is not directly influenced by the changes in plasma AF during HD.In study 2 different dialysis filters were compared to clarify whether using a high-flux (HF) dialyzer favors plasma or SAF removal compared to low-flux (LF) dialyzer. Twenty-eight patients were treated with either an HF-HD or LF-HD but otherwise unchanged conditions in a cross-over design. SAF was measured non-invasively with an AGE reader before and after HD. PAF was determined as total and non-protein-bound fractions. Corrections for hemoconcentrations by volume changes were made using the change in serum albumin. Paired and non-paired statistical analyses were used. The different treatments did not change SAF after LF- and HF-dialysis. Total, free, and protein-bound PAF were reduced after a single LF-HD by 21%, 28%, and 17%, respectively (P<.001). After HF-HD total and free PAF was reduced by 5% and 15%, respectively (P<.001), while protein-bound values were unchanged. The LF-HD resulted in a more pronounced reduction of PAF than did HF-HD (P<.001). Serum albumin correlated inversely with PAF in HF-HD. There was no significant change in SAF after dialysis, either with LF or with HF dialysis. Although only limited reductions in PAF were observed, these were more pronounced when performing LF dialysis. These data are not in overwhelming support of the use of HF dialysis in the setting used in this study.In the third study the effect on SAF was investigated using either glucose-containing or glucose-free dialysate. SAF and PAF were measured in patients on HD during standard treatment with a glucose-containing dialysate (n=24). After that, the patients were switched to a glucose-free dialysate for a 2 week period, and new measurements were performed on PAF and SAF.There was an increase of pre-dialysis SAF measured at the beginning of the study compared with the values one month later (as in study 4). By comparing pre- and post-dialysis values there was a significant decrease of SAF only when using glucose-free dialysate. Free PAF decreased independently whether glucose-containing or glucose-free dialysate was used. The important finding was that increase in SAF seemed possible to slow down using glucose-free dialysate.Study 4 was performed to investigate whether there are seasonal variations in SAF on a HD population. SAF was measured non-invasively with an AGE Reader in patients on HD at different seasonal periods during one year such as February-May (N=31), May–August (N=28), August–March (N=25). SAF was measured before HD. Paired statistical analyses were performed between each two periods. Unexpectedly there was at a median 6% increase in SAF during the winter (p=0.004) and a 11% decrease from 4.0 to 3.5 arbitrary units of the SAF during the summer (p<0.001). The study concluded that SAF shows seasonal variation. The cause of these changes could not be clarified. A beneficial effect may be due to extended exposure to sunlight during the summer and/or to different dietary intakes during the seasons.In conclusion, these interventional studies confirmed that PAF is lowered by dialysis. SAF was only decreased by HD when using glucose-free dialysate. SAF was not influenced by a single HD, with glucose-containing dialysate, independent of using HF or LF filters. These data favor glucose-free dialysate as a possible measure to slow down the progress of tissue AGE compared to glucose-containing dialysate. Longitudinal studies will help to clarify this issue further.
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| 4. |
- Stenberg, Jenny, 1976-
(författare)
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Fluid Management in Haemodialysis : Studies on current practices and new methods
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Chronic fluid overload has been identified as an independent predictor of mortality in haemodialysis patients, and 30% remain fluid overloaded at dry weight. The use of bioimpedance spectroscopy (BIS) in fluid management may improve blood pressure control and cardiovascular status. However, the importance of regular and careful clinical assessment of fluid balance is repeatedly emphasised.This thesis is based on five papers and the overall aim was to investigate current practices and new methods for fluid management in haemodialysis, and to develop a management tool for dry weight determination, based on multiple complementary methods. The purpose was to contribute to reduced prevalence of fluid overload and intradialytic symptoms in haemodialysis patients, by providing the healthcare team and the patient with a tool, that facilitates communication and enables informed decision-making in dry weight determination.In the initial, cross-sectional study, clinical praxis for dry weight assessment in Sweden and Denmark was investigated. A wide variation in routines was found. Despite high access, BIS was sparsely used. Instead, nurses’ authorisation to adjust haemodialysis patients’ dry weight was associated with improved fluid status. The second study had a qualitative approach. Focus group interviews, with healthcare professionals, were carried out to achieve a deeper understanding of the factors preventing or facilitating the use of BIS. In the third study, the usefulness of a biomarker, brain natriuretic peptide (BNP), for assessing fluid status in haemodialysis patients, was investigated. An association between BNP and fluid overload was established. The between-individual variation in BNP levels was greater than the within-individual variation over time. Therefore, if BNP is to be used as a marker for fluid overload, repeated measurements are required. In the fourth study, we developed and validated a multifactorial decision aid, Recova®, that incorporates BIS in dry weight determination. Recova® is based on physiological parameters routinely measured in haemodialysis and provides guidance on when and how to respond to recognised fluid alterations. In the fifth study, the decision aid’s effect on volume status was tested in a cohort of haemodialysis patients. Implementation of Recova® had effect on fluid status symptoms, BIS-measured hydration status and NT-proBNP levels.
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| 5. |
- Holmberg, Benny, 1958-
(författare)
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Analysis of risk factors in patients with severe chronic kidney disease. The role of atorvastatin.
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background and aim: There had been no randomized end-point studies with statins for patients with severe renal failure. The purpose of this prospective, open, randomized, controlled study was to investigate whether atorvastatin (10 mg/day) would alter cardiovascular end-points and the overall mortality rate of patients with chronic kidney disease stage 4 or 5 (creatinine clearanceMaterial & Methods: This was an open, prospective, randomized study. A total of 143 patients were included: 73 were controls and 70 were prescribed 10 mg/day of atorvastatin. As efficacy variables, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglyceride levels were determined at the start of the study and at 1, 3, 6, 12, 18, 24, 30 and 36 months. The primary end-points were all cause of mortality, non-lethal acute myocardial infarction, and coronary artery intervention. Various risk factors were studied. In the 97 patients on haemodialysis inter dialysis weight gain (IDWG) was calculated as ultrafiltration in kg/body weight in kg given in percentage of the weight. The burden of IDWG was analyzed.Results: In the atorvastatin group, total cholesterol and low-density lipoprotein cholesterol were significantly reduced, the latter by 35% at 1 month and then sustained. Atorvastatin was withdrawn in 23% of patients due to unacceptable side effects, most frequent complaints being gastrointestinal discomfort and headache. Primary end-points occurred in 74% of the subjects. There was no difference in cardiovascular endpoint and survival between the control and atorvastatin groups. The 5-year end-point-free survival rate from study entry was 20%. There was no evidence of more benefit of atorvastatin for patients with diabetes mellitus and chronic kidney disease versus the other patients; instead plasma fibrinogen increased. The IDWG was significantly larger in patients who suffered from end-points due to cardiovascular reasons, cardiac reasons, congestive heart failure, aortic aneurysm, and intracerebral bleeding.Conclusion: These data showed that in contrast to other patient groups, patients with severe chronic kidney disease 4 and 5, including those with diabetes mellitus, seem to have no benefit from 10mg/day of atorvastatin. Instead we found a high IDWG to be an important risk factor that should be prevented. There was no evident connection between atorvastatin medication and IDWG.
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| 6. |
- Peters, Björn, 1978-
(författare)
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Clinical and quality aspects of native and transplant kidney biopsies in Sweden
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Percutaneous kidney biopsies have been performed since 1944 to establish diagnoses and treatment. Risk factors based on a limited amount of data have shown age, blood pressure, kidney function and needle size as some risk factors for biopsy complications. Although the techniques of biopsy have improved over the years, it is still an invasive procedure and serious complications can occur.The overall aim of this thesis was to obtain a large series of data from biopsy procedures and to use these to bring further light on risk factors to help minimize the risk for patients and to optimize diagnostics. Specific aims were to clarify if different factors, such as gender, diagnoses, localization of biopsies, needle types and sizes, could be useful to help minimize complication risks in native kidney biopsies (Nkb) and transplant kidney biopsies (Txb). Another point to investigate was the value of the Resistive Index (RI) obtained at ultrasound before performing Txb.Materials and methods: A protocol for prospective multicentre registration of various factors and complications associated with Nkb and Txb was designed. Consecutive data were obtained from seven hospitals. All biopsies, except one computer tomography-guided Nkb, were performed using real-time ultrasound guidance and an automated spring-loaded biopsy device. For the biopsies 14- to 20- Gauge (G) needles were used. The kidney function level, i.e. estimated glomerular filtration rate (eGFR), was calculated using the Modification of Diet in Renal Disease (MDRD) formula (GFR in mL/min per 1.73m2). For statistical analyses the IBM SPSS Statistic 22 (Armonk, NY, USA) and OpenEpi (Open Source Epidemiologic Statistics for Public Health, www.OpenEpi.com) were used. Data were presented as Odds Ratio (OR), Risk Ratio (RR) and Confidence Intervals (CI). A two sided p-value of <0.05 was considered significant. In total 1299 consecutive biopsies (1039 native and 260 transplant kidneys) in 1178 patients (456 women and 722 men) were used for investigation. The median age of patients was 55 years (range 16 to 90 years). Major (require an intervention) and minor biopsy complications (no need of intervention) were registered.Results: The overall frequency of biopsy complications for Nkb was 8.8% (major 6.7%, minor 2.1%) and for Txb was 6.5% (major 3.8%, minor 2.7%); no death. Women had a higher risk for development of major (10.7% versus 4.7%, OR 2.4, CI 1.4-4.2) and overall biopsy complications (13.2% versus 6.5%, OR 2.2, CI 1.4-3.5) compared to men in Nkb. In Nkb, major complications were more common after biopsies from the right kidney in women versus men (10.8% vs 3.1%, OR 3.7, CI 1.5–9.5), in patients with lower versus higher BMI (25.5 vs 27.3, p=0.016) and for younger versus older age (44.8 vs 52.3 years, p=0.002). Lower (90 mmHg) compared to higher (98 mmHg) mean arterial pressure in Txb indicated a risk of major complications (p=0.039). Factors such as number of passes and kidney function did not influence complication rates. Biopsy needles of 16 G compared to 18 G showed more glomeruli per pass in Nkb (11 vs 8, p<0.001) and in Txb (12 vs 8, p<0.001). Sub-analysis revealed that 18 G 19 mm side-notch needles in Nkb resulted in more major (11.3% vs 3%, OR 4.1, CI 1.4-12.3) and overall complications (12.4% vs 4.8%, OR 2.8, CI 1.1-7.1) in women than in men. If the physician had performed less compared to more than four Nkb per year, minor (3.5% vs 1.4%, OR 2.6, CI 1.1-6.2) and overall complications (11.5% vs 7.4%, OR 1.6, CI 1.1-2.5) were more common. The localization of biopsy within the kidney (Nkb and Txb) was not a risk factor for complications. Patients with IgA-nephritis compared to patients with other diseases had a higher risk of major complications (11.7% vs 6.4 %, OR 1.8, CI 1.1–3.2). More major complications were found in Nkb if they had higher versus lower degree of glomerulosclerosis (31% vs 20 %, p=0.008) and in Txb if there was a higher versus lower degree of interstitial fibrosis (82% vs 33%, p<0.001). Re-biopsies (Nkb) were more common in patients with IgA-nephritis than those with other diseases (4.7% vs 1.3 %, OR 4, CI 1.5–11), in younger versus older age (42.6 vs 52.3 years, p=0.031), and in those with a higher versus lower degree of interstitial fibrosis (63% vs 34 %, p=0.046). In Txb, a RI≥0.8 compared to RI<0.8 predicted major (13.3% vs 3.2%, RR 4.2, CI 1.3-14.1) and overall biopsy complications (16.7% vs 5.3%, RR 3.2, CI 1.2-8.6). In the group <0.8, RI correlated with age (rs=0.28, p<0.001) and systolic blood pressure (rs=0.18, p=0.02). In the group ≥0.8, RI correlated with degree of interstitial fibrosis (rs=0.65, p=0.006) and systolic blood pressure (rs=0.40, p=0.03). The multiple regression analysis showed that the <0.8 RI group correlated only with age (p<0.001), whereas the ≥0.8 RI group correlated only with the degree of interstitial fibrosis (p=0.003).Conclusions: The present results motivate greater attention to be paid to the possibility of major side-effects after Nkb in women and biopsies from their right side, but as well in younger patients, and in those with lower BMI. This also applies for patients with presumptive IgA-nephritis and higher degree of glomerulosclerosis. In Txb, patients with higher degree of interstitial fibrosis had a greater risk of major complications. Moreover, the present data indicate that Nkb and Txb should be preferably taken with 16 G needles with 20 mm sample size. This results in better histological quality and there is a lower risk for major complications as compared to 18 G needles. The localization of biopsy within the kidney (Nkb and Txb) does not alter complication rates. For Nkb there were fewer complications if the physician had performed at least four biopsies per year. A RI≥0.8 in Txb indicates a greater risk for major and overall complications.
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| 7. |
- Ulf, Forsberg, 1968-
(författare)
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Presence of microemboli during haemodialysis and methods to reduce the exposure to microbubbles
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Despite chronic dialysis treatment, patients with end stage renal disease undergoing maintenance haemodialysis (HD) remain at a substantially increased risk of morbidity. Previous reports using Doppler ultrasound (DU) during HD have revealed microembolic signals (ME) in the venous circulation.In vitro studies confirm the emergence of microbubbles of air that may pass the security system of the HD circuit without triggering the alarm. The aim of this thesis was to elucidate the presence of ME during HD and examine methods that might reduce exposure to ME in vivo. The first study utilized DU to verify the presence of ME in 40 patients during standard HD. Investigation within 30 minutes after the start of HD and just before the end of session revealed the presence of ME in the venous blood line during both phases. The air trap did not alert for the presence of ME. This indicated that ME may pass into the patient during the entire HD run.Study 2 analyzed the presence of ME prior to start and during HD when measured at the AV-access and also carotid artery. A total of 54 patients were examined using DU as the investigative technique. ME increased significantly after start of HD in the AV-access, but also at the carotid artery site. These data indicated that ME can enter the body and even pass the lung barrier. The question arose if microbubbles of air are resorbed or may cause ischemic lesions in organs such as the brain.Study 3 examined whether the amount of ME detected in the AV-access would change by using either a high or a low blood level in the venous air trap/chamber. This was a prospective, randomized and double-blind study of 20 HD patients who were their own controls. After 30 min of standard HD, measurement of ME with DU was performed for two minutes. The chamber setting was changed and after another 30 minutes a new recording was carried out for two minutes. Data showed that setting a high blood level significantly reduced the extent of ME that entered the patient. The results also indicated that ME consisted mainly of microbubbles.In study 4, twenty patients were randomized in a cross-over setting of HD. Three options were used: a wet-stored dialyzer with high blood level (WH) and a dry-stored dialyzer using either a high (DH) or a low (DL) blood level in the venous chamber. The exposure of ME, detected by DU, was least when using mode WF, more with mode DH, and most with mode DL. There was a correlation between higher blood flow and more extensive exposure to ME.Study 5 was an autopsy study of a chronic HD patient with the aim of searching for microbubbles deposited in organs. Microbubbles of gas were verified in the vessels of the lungs, brain and heart. By using a fluorescent stain of anti-fibrinogen it was verified that the microbubbles were covered by clots that had to be preformed before death occurred. This indicated that air microbubbles are not completely absorbed and could result in embolic deposition in the organs of HD patients.In conclusion, these in vivo studies showed that ME pass the air trap without inducing an alarm and enter the venous blood line of the patient. The data confirmed the presence of ME in the AV-access and also in the carotid artery. Autopsy data of a deceased HD patient demonstrated the presence of microbubbles in the capillaries of the lungs, but also in the systemic circulation such as in the brain and the heart. A high blood level in the venous chamber and wet-stored dialyzer can reduce, but not eliminate the exposure to microbubbles for patients undergoing HD.
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| 8. |
- Nasic, Salmir, et al.
(författare)
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Sex-specific time trends of long-term graft survival after kidney transplantation : a registry-based study
- 2023
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Ingår i: Renal failure. - : Taylor & Francis. - 0886-022X .- 1525-6049. ; 45:2
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Tidskriftsartikel (refereegranskat)abstract
- Background: Sex-specific trends over time with respect to kidney graft survival have scarcely been described in earlier studies. The present study aimed to examine whether kidney graft survival differs between women and men over time.Methods: This study was based on prospectively collected data extracted from a quality registry including all kidney transplant patients between January 1965 and September 2017 at the transplantation center of a university hospital in Sweden. The transplantation center serves a population of approximately 3.5 million inhabitants. Only the first graft for each patient was included in the study resulting in 4698 transplantations from unique patients (37% women, 63% men). Patients were followed-up until graft failure, death, or the end of the study. Death-censored graft survival analysis after kidney transplantation (KT) was performed using Kaplan-Meier analysis with log-rank test, and analysis adjusted for confounders was performed using multivariable Cox regression analysis.Results: Median age at transplantation was 48 years (quartiles 36–57 years) and was similar for women and men. Graft survival was analyzed separately in four transplantation periods that represented various immunosuppressive regimes (1965-1985, 1986–1995, 1996–2005, and 2006–2017). Sex differences in graft survival varied over time (sex-by-period interaction, p = 0.026). During the three first periods, there were no significant sex differences in graft survival. However, during the last period, women had shorter graft survival (p = 0.022, hazard ratio (HR) 1.71, 95% confidence interval (CI) 1.1–2.7, adjusted for covariates). Biopsy-proven rejections were more common in women.Conclusions: In this registry-based study, women had shorter graft survival than men during the last observation period (years 2006–2017).
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| 9. |
- Skagerlind, Malin, 1975-
(författare)
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How to reduce the exposure to anticoagulants when performing haemodialysis in patients with a bleeding risk : a study of methods used in clinical practise
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- When a patient suffers from kidney failure and also has an enhanced risk of bleeding, the standard haemodialysis (HD) treatment becomes a problem. When human blood comes in contact with artificial material, as in the tubing system and in the dialyser (the extra corporeal circuit, ECC), the coagulation system is activated. If there is no increased risk of bleeding a bolus dose of anticoagulation is given intravenous to the patient before HD to avoid clotting. The most common anticoagulants used during HD are unfractionated heparin (UFH) and low molecule weight heparins (LMWH). Without anticoagulants there will be a total coagulation (clotting) of the blood in the ECC, an interrupted treatment and a blood loss of up to 300 ml for the patient. With an ongoing bleeding or an increased risk of bleeding in a patient that also needs HD, there are various alternatives that can be used to avoid or lower the need of anticoagulation. However, there is no golden standard, neither in Sweden or worldwide.The overall aim of this Thesis was to evaluate the safety and the efficacy of various models of anticoagulation that may be used in patients with a bleeding risk.The first study examined a low-dose anticoagulation model that was locally developed in Umeå, Sweden in the 1980s. The primary aim was to clarify to what extent this priming model was safe and efficient during intermittent HD for patients with a bleeding risk. Consecutive acute HD treatment protocols (248 procedures in 68 patients) were included. There were 178 patients with an increased bleeding risk who had their ECC (tubes, chambers and dialyser) flushed through (priming) with Heparin-Albumin-priming (HA-priming). There were 70 patients with no increased bleeding risk who received standard intermittent HD (priming with saline); these patients also received a bolus dose of anticoagulation intravenous before dialysis.The low-dose method entailed priming of the ECC with HA-priming with the intention to coat the surfaces with the solution and protect from blood to attach to it. Comparisons were made to dialysis in patients with no increased bleeding risk, who had received standard anticoagulation (SHD) with UFH or LMWH. The priming solutions were always discarded before HD was initiated. None or limited doses of UFH were added during the HD. There was no difference in extent of prematurely interrupted HA-primed dialysis compared to SHD (2.2 vs. 4.3%, p = 0.62). No secondary bleeding due to anticoagulation was reported in the protocols.Study 2 was performed to further clarify data in an extended group of acute intermittent HD using either HA-priming (885 treatments in 221 patients at risk of bleeding) or SHD (523 treatments in 100 patients with no bleeding risk who had received standard anticoagulation). In this extended study there was no difference in the extent of prematurely interrupted HA-dialysis (0.8%) compared to SHD (1%, p = 0.8). The results also showed less clotting for dialysers with a membrane area ≤ 1.7 m2. No secondary bleeding due to anticoagulation was reported in the protocols.Study 3 was an experimental in vitro study. The aim was to compare the anticoagulation effect of priming the ECC with different concentrations of albumin and/or heparin in saline. Priming with saline only was also evaluated. The priming fluids were always discarded after priming. Fresh whole blood from healthy human donors was used to perform in vitro dialyses in a recirculation system. The donated blood was equally divided into two bags, whereas one bag represented the control group and the other the intervention group. Priming with saline only and priming with albumin in saline resulted in rapid clotting of the blood in the ECC. These experiments indicated that HA-priming or priming with heparin in saline enabled fulfilment of all the in vitro dialyses.Study 4 was a clinical randomized cross-over study. The aim was to minimize the use of anticoagulant during HD in patients with a bleeding risk. Four different low-dose anticoagulation models were compared to SHD. Stable chronic HD patients participated in the study. The patients were their own controls. Aside from SHD, the four models of low-dose anticoagulation used were Heparin priming (H), HA-priming (HA), HA-priming in combination with a citrate containing dialysate (HAC), and a dialyser manufactured with a heparin-grafted membrane (Evodial®). The H-model was least suitable with 33 % interrupted treatments and the most extra doses of UFH needed. The HAC and Evodial® models were most preferable, both with an activated partial thromboplastin time (APTT) within references and with the least amounts of UFH needed. Evodial® had a lower urea reduction rate compared to the other models. HAC was the only model with no interrupted treatment. One patient suffered from a severe hypersensitivity reaction using Evodial®. No other side-effects were reported during the study.In conclusion an acute kidney injury is a life-threating situation that also includes patients with an increased bleeding risk and in need of HD for survival. If intermittent HD is the selected option, a priming of the ECC with a HA-solution in combination with a citrate containing dialysis fluid (HAC) is a safe and sufficient option for anticoagulation. Another option could be the heparin-grafted dialyser (Evodial®), although with a lower clearance coefficient and with a caution for a risk for hypersensitivity reaction or anaphylaxis.
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- Uhlin, Fredrik, 1965-
(författare)
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Haemodialysis Treatment Monitored On-line by Ultra Violet Absorbance
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes and evaluates an optical method utilizing ultra violet (UV) absorbance for on-line monitoring of haemodialysis treatment. Increased efficiency of haemodialysis treatment is considered to correlate to decreased morbidity and mortality when urea clearance (Kt/V) is elevated. However, further improvements have not been achieved at a higher Kt/V. The mortally rate in the haemodialysis population is still high (27% in Sweden).Urea as the clinical marker is under discussion, partly due to urea being non-toxic, but also that the uraemic syndrom is the result of a cumulative retention of innumerable involved compounds.On-line monitoring systems based on urea determination for improved dialysis efficiency have been suggested and developed in different settings over the last two decades, but have not achieved worldwide utilisation as routine clinical equipment. This thesis demonstrates that the UV-technique utilising 280, 285 and 297 nm is capable of estimating dialysis efficiency in therms of Kt/V, nutritional status in terms of protein catabolic rate (PCR), with the same characteristics as existing methods. One novel finding using UV-absorbance with high sampling rates is the on-line visualisation of the clearance process for following variations in clearance caused by clinical events and disturbances as well as during and after adjustments. The fact that the UV-absorbance technique does not measure urea directly but has high correlation to several other both UV-absorbing and not-absorbing solutes makes it suitable to reflect a more overall solute retention process. Finally, a new efficiency parameter based on the calculation of the area under UV- curve (clearance curve), is suggested to reflect the total removal of some solutes.In summary the UV-technique has the potential to be an additional tool to evaluate improvements of dialysis efficiency, which may result in decreased morbidity, longer life span and enhanced quality of life for the haemodialysis patients.
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