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.

A diálise peritoneal (DP) é uma técnica de reposição renal utilizada mundialmente tanto na medicina como na medicina veterinária. Na medicina veterinária, a pesquisa por técnicas minimamente invasivas para a implantação de cateteres de DP se mostra de grande valia, visto que a indicação de diálise em animais é, principalmente, para casos de injúria renal aguda e agudização da doença renal crônica, e, muitas vezes, o paciente não tem condições de aguardar a cicatrização da ferida cirúrgica para iniciar o procedimento de diálise. O objetivo desta pesquisa foi descrever a técnica de omentectomia e de implantação do cateter de Tenckhoff pelo acesso videolaparoscópico com três portais em coelhos, além de avaliar a funcionalidade do cateter. Foram utilizados oito coelhos adultos, fêmeas, da raça Nova Zelândia para a realização de implantação de cateter de Tenckhoff e omentectomia por videolaparoscopia. As medianas do Tempo Cirúrgico Total (TCT), Tempo para Omentectomia (TOm) e Tempo para implantação do Cateter de Tenckhoff (TICT) foram 65,5, 30, e 5 minutos, respectivamente. As principais complicações apresentadas pela técnica foram hemorragia e herniação pela ferida cirúrgica. Foram realizados oito procedimentos de DP em cada animal, sendo o primeiro iniciado três horas após a implantação do cateter. A principal complicação observada foi o vazamento do dialisato para o espaço subcutâneo, ocorrido em todos os animais. Com base na metodologia utilizada e nos resultados obtidos neste estudo, pode-se concluir que a técnica de omentectomia videolaparoscópica é factível em coelhos, permitindo que o procedimento seja realizado de forma segura e sem intercorrências significativas, além de permitir adequado posicionamento do cateter. / Peritoneal dialysis (PD) is a renal replacement technique used worldwide in both medicine and veterinary medicine. In veterinary medicine, the search for minimally invasive techniques for PD catheters implantation is of great value. The indication of dialysis in animals is mainly for cases of acute renal injury and exacerbation of chronic kidney disease and, the patient is often unable to wait for wound healing to begin the dialysis procedure. The objective of this research was to describe the technique of Tenckhoff catheter implantation and omentectomy by videolaparoscopic access with three portals in rabbits. In addition, to evaluating the catheter functionality. Eight female New Zealand rabbits were used to perform omentectomy and videolaparoscopic Tenckhoff catheter implantation. Median Total Surgical Time (TCT), Time for Omentectomy (TOm) and Time for Tenckhoff Catheter Implantation (TCTI) were 65.5, 30, and 5 minutes, respectively. The main complications presented by the technique were hemorrhage and herniation in the surgical wound. Eight procedures of PD were performed in each animal, the first one being started three hours after catheter implantation. The main complication observed was the leakage of the dialysate into the subcutaneous space, which occurred in all animals. Based on the methodology used and the results obtained in this study, it can be concluded that the videolaparoscopic omentectomy technique is feasible in rabbits, allowing the procedure to be performed safely and without significant intercurrences, besides allowing the adequate catheter positioning.

A diálise peritoneal (DP) é uma técnica de reposição renal utilizada mundialmente tanto na medicina como na medicina veterinária. Na medicina veterinária, a pesquisa por técnicas minimamente invasivas para a implantação de cateteres de DP se mostra de grande valia, visto que a indicação de diálise em animais é, principalmente, para casos de injúria renal aguda e agudização da doença renal crônica, e, muitas vezes, o paciente não tem condições de aguardar a cicatrização da ferida cirúrgica para iniciar o procedimento de diálise. O objetivo desta pesquisa foi descrever a técnica de omentectomia e de implantação do cateter de Tenckhoff pelo acesso videolaparoscópico com três portais em coelhos, além de avaliar a funcionalidade do cateter. Foram utilizados oito coelhos adultos, fêmeas, da raça Nova Zelândia para a realização de implantação de cateter de Tenckhoff e omentectomia por videolaparoscopia. As medianas do Tempo Cirúrgico Total (TCT), Tempo para Omentectomia (TOm) e Tempo para implantação do Cateter de Tenckhoff (TICT) foram 65,5, 30, e 5 minutos, respectivamente. As principais complicações apresentadas pela técnica foram hemorragia e herniação pela ferida cirúrgica. Foram realizados oito procedimentos de DP em cada animal, sendo o primeiro iniciado três horas após a implantação do cateter. A principal complicação observada foi o vazamento do dialisato para o espaço subcutâneo, ocorrido em todos os animais. Com base na metodologia utilizada e nos resultados obtidos neste estudo, pode-se concluir que a técnica de omentectomia videolaparoscópica é factível em coelhos, permitindo que o procedimento seja realizado de forma segura e sem intercorrências significativas, além de permitir adequado posicionamento do cateter. / Peritoneal dialysis (PD) is a renal replacement technique used worldwide in both medicine and veterinary medicine. In veterinary medicine, the search for minimally invasive techniques for PD catheters implantation is of great value. The indication of dialysis in animals is mainly for cases of acute renal injury and exacerbation of chronic kidney disease and, the patient is often unable to wait for wound healing to begin the dialysis procedure. The objective of this research was to describe the technique of Tenckhoff catheter implantation and omentectomy by videolaparoscopic access with three portals in rabbits. In addition, to evaluating the catheter functionality. Eight female New Zealand rabbits were used to perform omentectomy and videolaparoscopic Tenckhoff catheter implantation. Median Total Surgical Time (TCT), Time for Omentectomy (TOm) and Time for Tenckhoff Catheter Implantation (TCTI) were 65.5, 30, and 5 minutes, respectively. The main complications presented by the technique were hemorrhage and herniation in the surgical wound. Eight procedures of PD were performed in each animal, the first one being started three hours after catheter implantation. The main complication observed was the leakage of the dialysate into the subcutaneous space, which occurred in all animals. Based on the methodology used and the results obtained in this study, it can be concluded that the videolaparoscopic omentectomy technique is feasible in rabbits, allowing the procedure to be performed safely and without significant intercurrences, besides allowing the adequate catheter positioning.

A diálise peritoneal (DP) é uma técnica de reposição renal utilizada mundialmente tanto na medicina como na medicina veterinária. Na medicina veterinária, a pesquisa por técnicas minimamente invasivas para a implantação de cateteres de DP se mostra de grande valia, visto que a indicação de diálise em animais é, principalmente, para casos de injúria renal aguda e agudização da doença renal crônica, e, muitas vezes, o paciente não tem condições de aguardar a cicatrização da ferida cirúrgica para iniciar o procedimento de diálise. O objetivo desta pesquisa foi descrever a técnica de omentectomia e de implantação do cateter de Tenckhoff pelo acesso videolaparoscópico com três portais em coelhos, além de avaliar a funcionalidade do cateter. Foram utilizados oito coelhos adultos, fêmeas, da raça Nova Zelândia para a realização de implantação de cateter de Tenckhoff e omentectomia por videolaparoscopia. As medianas do Tempo Cirúrgico Total (TCT), Tempo para Omentectomia (TOm) e Tempo para implantação do Cateter de Tenckhoff (TICT) foram 65,5, 30, e 5 minutos, respectivamente. As principais complicações apresentadas pela técnica foram hemorragia e herniação pela ferida cirúrgica. Foram realizados oito procedimentos de DP em cada animal, sendo o primeiro iniciado três horas após a implantação do cateter. A principal complicação observada foi o vazamento do dialisato para o espaço subcutâneo, ocorrido em todos os animais. Com base na metodologia utilizada e nos resultados obtidos neste estudo, pode-se concluir que a técnica de omentectomia videolaparoscópica é factível em coelhos, permitindo que o procedimento seja realizado de forma segura e sem intercorrências significativas, além de permitir adequado posicionamento do cateter. / Peritoneal dialysis (PD) is a renal replacement technique used worldwide in both medicine and veterinary medicine. In veterinary medicine, the search for minimally invasive techniques for PD catheters implantation is of great value. The indication of dialysis in animals is mainly for cases of acute renal injury and exacerbation of chronic kidney disease and, the patient is often unable to wait for wound healing to begin the dialysis procedure. The objective of this research was to describe the technique of Tenckhoff catheter implantation and omentectomy by videolaparoscopic access with three portals in rabbits. In addition, to evaluating the catheter functionality. Eight female New Zealand rabbits were used to perform omentectomy and videolaparoscopic Tenckhoff catheter implantation. Median Total Surgical Time (TCT), Time for Omentectomy (TOm) and Time for Tenckhoff Catheter Implantation (TCTI) were 65.5, 30, and 5 minutes, respectively. The main complications presented by the technique were hemorrhage and herniation in the surgical wound. Eight procedures of PD were performed in each animal, the first one being started three hours after catheter implantation. The main complication observed was the leakage of the dialysate into the subcutaneous space, which occurred in all animals. Based on the methodology used and the results obtained in this study, it can be concluded that the videolaparoscopic omentectomy technique is feasible in rabbits, allowing the procedure to be performed safely and without significant intercurrences, besides allowing the adequate catheter positioning.

<p>Diss. (sammanfattning) Umeå : Umeå universitet, 1994, härtill 5 uppsatser.</p> / digitalisering@umu

The aims of this thesis were to: 1) develop a new method for the determination of interstitial pH at rest and during exercise in vivo, 2) systematically explore the effects of different ingestion regimes of 300 mg.kg-1 sodium citrate on blood and urine pH at rest, and 3) to combine the new interstitial pH technique with the findings of the second investigation in an attempt to provide a greater understanding of H+ movement between the extracellular compartments. The purpose of the first study was to develop a method for the continuous measurement of interstitial pH in vastus lateralis was successfully developed using microdialysis and 2,7-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF). To avoid the presence of an artificial alkalosis during exercise, it was necessary to add 25 mM HCO3- to the perfusate. The outlet of the probe was cut less than 10 mm from the skin and connected to a stainless steel tube completing the circuit to a microflow-through cuvette (8 fÝl) within a fluorescence spectrophotometer. This prevented the loss of carbon dioxide from the dialysate and any subsequent pH artefact. Interstitial pH was collected from six subjects before, during and after five minutes of knee-extensor exercise at three intensities 30, 50, and 70 W. Mean,,bSEM interstitial pH at rest was 7.38,,b0.02. Exercise reduced interstitial pH in an almost linear fashion. The nadir value for interstitial pH at 30, 50 and 70 W exercise was 7.27, 7.16 and 7.04, respectively. The lowest pH was obtained 1 min after exercise, irrespective of workload, after which the interstitial pH recovered in a nearly exponential manner. The mean half time of interstitial recovery was 5.2 min. The changes in interstitial pH exceeded the changes in venous blood pH. This study demonstrated that interstitial pH can be measured using microdialysis and that it is continuously decreased during muscle activity. The purpose of the second study was to establish an optimal ingestion regime for the ingestion of 300 mg.kg-1 of sodium citrate and maximise the alkalotic effect while minimising any side effects. Increasing the effectiveness of alkali ingestion may lead to further increases in muscle performance. Ingesting 300 mg.kg-1 sodium citrate at a rate of 300 mg.min-1 was identified as the optimal ingestion regime to maximise alkalosis at rest, which occurred 3.5 h post-ingestion. This was determined by monitoring eight human subjects ingesting 300 mg.kg-1 sodium citrate at five different rates, control (no ingestant), bolus, 300, 600 and 900 mg.kg.min-1 on five days separated by at least 48 hours. Sodium citrate was ingested in capsule form with water ad libitum, with the exception of bolus, which was combined with 400 ml less than 25 percent orange juice and consumed in less than 1 min. Arterialised blood (mean 71.3,,b3.5 mmHg) acid-base and electrolyte status was assessed via the withdrawal of ~5 ml of blood every 30 min across an eight hour duration, placed on ice and analysed within five minutes. No alkalotic difference was found between ingestion rates (mean 7.445,,b0.004, 7.438,,b0.004 and 7.442,,b0.004 for 300, 600 and 900 mg.min-1, respectively). All experimental ingestion regimes were associated with elevations in [HCO3-] (29.6, 29.7, 29.8, 29.9 and 26.3 mmol.l-1 for bolus, 300, 600, 900 and control, respectively). The 300 ingestion regime had the greatest impact on [H+], a 0.66 meq.l-1,,e10-8 change. Bolus ingestion (3.93,,b0.08 mmol.l-1) of sodium citrate had no effect on control (4.06,,b0.08 mmol.l-1) blood [K+], however, 300 mg.min-1 decreased blood [K+] (p less than 0.05). There was no effect of sodium citrate on blood [Cl-], but after 2.5 h blood [Cl-] was lower than pre-ingestion values (p less than0.05). All ingestion rates of sodium citrate increased (p less than 0.05) urine pH above control. This is the first study to investigate the effect of varying ingestion rates on acid-base status at rest in humans. The results suggest that ingesting sodium citrate in small doses in quick succession induce a greater blood alkalosis than the commonly practised bolus protocol. Using the interstitial pH technique described above and the optimal ingestion regime (300 mg.min-1) identified above, the final experiment was designed to assess the influence of sodium citrate ingestion on interstitial pH at both rest and during exercise. Five subjects ingested 300 mg.kg-1 sodium citrate at 300 mg.min-1 again in capsule form with water ad libitum. Prior to ingestion, each subject had a cannula placed into their cephalic vein and one microdialysis probe (CMA-60) inserted into their left thigh, orientated along the fibres of vastus lateralus. This probe was used for the measurement of pH as described above. At the end of this period, an exercise protocol required five subjects to perform light exercise (10 W) for 10 min, before starting an intense exercise period (~90-95% leg VO2peak) to exhaustion followed by a 15 min recovery period. Dialysate and blood samples were collected across all periods. Mean,,bSEM interstitial pH for placebo and alkalosis were 7.38,,b0.12 and 7.24,,b0.16, respectively. Sodium citrate ingestion was not associated with an interstitial alkalosis. An exercise induced acidosis was observed in the interstitium during placebo but not during alkalosis (p less than 0.05). Mean,,bSEM venous pH were 7.362,,b0.003 and 7.398,,b0.003 for placebo and alkalosis, respectively. Sodium citrate ingestion was not associated with a venous alkalosis. Sodium citrate ingestion was associated with an increase in mean,,bSEM venous [HCO3-] (placebo 25.5,,b0.2, alkalosis 28.1,,b0.2). This increase in the blood bicarbonate buffer system was not associated with an increase in time to exhaustion (placebo 352,,b71, alkalosis 415,,b171). This was the first study to investigate the effects of sodium citrate ingestion on interstitial pH. The results of this study demonstrated that an interstitial alkalosis does not ensue after alkali ingestion, however, it was associated with the lack of an exercise induced acidosis suggesting an improved pH regulation during exercise.

Volume overload is a common feature in patients on haemodialysis (HD). This contributes significantly to the cardiovascular disease burden seen in these patients. Clinical assessments of the volume state are often inaccurate. Techniques such as interdialytic blood pressure, relative blood volume monitoring, bioimpedance are available to improve clinical effectives. However all these techniques exhibit significant shortcomings in their accuracy, reliability and applicability at the bed side. We evaluated the usefulness of a dual compartment monitoring technique using Continuous Segmental Bioimpedance Spectroscopy (CSBIS) and Relative Blood Volume (RBV) as a tool to assess hydration status and determine dry weight. We also sought to evaluate the role of Atrial Natriuretic Peptide (ANP) and B-type Natriuretic Peptide (BNP) as a volume marker in dialysis patients. The Retrospective analysis of a historical cohort (n = 376, 55 Diabetic) showed a significant reduction in post-dialysis weights in the first three months of dialysis (72.5 to 70kg, p<0.027) with a non-significant increase in weight between months 6-12. The use of anti-hypertensive agents reduced insignificantly in the first 3 months, increased marginally between months 3-6 and significantly increased over the subsequent 6 months. The residual urea clearance (KRU) fell and dialysis times increased. The cohort was very different to that dialysing at Tassin and showed a dissociation between weight reduction and BP control. This may relate to occult volume overload. CSBIS-RBV monitoring in 9 patients with pulse ultrafiltration (pulse UF) showed distinct reproducible patterns relating to extra cellular fluid (ECF) and RBV rebound. An empirical Refill Ratio was then used to define the patterns of change and this was related to the state of their hydration. A value closer to unity was consistent with the attainment of best achievable target weight. The refill ratio fell significantly between the first (earlier) and third (last) rebound phase (1.97 ± 0.92 vs 1.32 ± 0.2). CSBIS monitoring was then carried out in 31 subjects, whilst varying dialysate composition, temperature and patient posture to analyse the effects of these changes on the ECF trace and to ascertain whether any of these interventions can trigger a change in the slope of the ECF trace distinct to that caused by UF. Only, isovolemic HD caused a change in both RBV and ECF in some patients that was explained by volume re-distribution due to gravitational shifts, poor vascular reactivity, sodium gradient between plasma and dialysate and the use of vasodilating antihypertensive agents. This has not been described previously. These will need to be explored further. The study did demonstrate a significant lack of comparability of absolute values of RECF between dialysis sessions even in the same patient. This too has not been described previously. This is likely to be due to subtle changes in fluid distribution between compartments. Therefore a relative changes must be studied. This sensitivity to subtle changes may increase the usefulness of the technique for ECF tracking through dialysis. The potential of dual compartment monitoring to track volume changes in real time was further explored in 29 patients of whom 21 achieved weight reductions and were able to be restudied. The Refill Ratio decreased significantly in the 21 patients who had their dry weights reduced by 0.95 ± 1.13 kg (1.41 ± 0.25 vs 1.25 ± 0.31). Blood pressure changes did not reach statistical significance. The technique was then used to examine differences in vascular refill between a 36oC and isothermic dialysis session in 20 stable prevalent patients. Pulse UF was carried out in both these sessions. There were no significant differences in Refill Ratios, energy removed and blood pressure response between the two sessions. The core temperature (CT) of these patients was close to 36oC and administering isothermic HD did not confer any additional benefit. Mean BNP levels in 12 patients during isovolemic HD and HD with UF did not relate to volume changes. ANP concentrations fell during a dialysis session in 11 patients from a mean 249 ± 143 pg/ml (mean ± SD) at the start of dialysis to 77 ± 65 pg/ml at the end of the session (p<0.001). During isolated UF levels did not change but fell in the ensuing sham phase indicating a time lag between volume loss and decreased generation. (136±99 pg/ml to 101±77.2 pg/ml; p<0.02) In a subsequent study ANP concentrations were measured throughout dialysis and in the post-HD period for 2 hours. A rebound in ANP concentration was observed occurring at around 90 min post-HD. The degree of this rebound may reflect the prevailing fluid state and merit further study. We have shown the utility of dual compartment monitoring with CSBIS-RBV technique and its potential in assessing volume changes in real time in haemodialysis patients. We have also shown the potential of ANP as an independent marker of volume status in the same setting. Both these techniques merit further study.