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No. of bitstreams: 1 josemunizpazelijunior.pdf: 868943 bytes, checksum: 7c1afb9837b6e1d73d18f7ea10b1401f (MD5) Previous issue date: 2012-11-29 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A Doença Renal Crônica (DRC) é um problema de saúde pública mundial e o número de pacientes inscritos em programas de terapia de substituição de função renal vem crescendo progressivamente. A morbimortalidade dos pacientes com DRC é impressionante e se deve principalmente a doença cardiovascular. A remoção inadequada de líquidos durante a hemodiálise é um dos principais fatores responsáveis por esta evolução desfavorável. A hipervolemia crônica leva a hipertensão, hipertrofia ventricular esquerda, congestão pulmonar e aumenta as taxas de hospitalização e mortalidade. A hipovolemia, por outro lado, se associa com náuseas, vômitos, diminuição da qualidade de vida, perda da função renal residual, trombose do acesso venoso e redução da adequação da diálise, devido às frequentes interrupções das sessões de diálise. O peso seco, definido como o menor peso atingido pelo paciente no final das sessões, quando a maior parte do excesso de líquido acumulado tenha sido removido, ainda é avaliado clinicamente, mas tem fraca correlação com a verdadeira volemia. Apesar de não podermos contar com método que seja “padrão-ouro”, devido às limitações na acurácia e aplicabilidade, várias exames complementares tem sido estudados e validados para a determinação mais precisa da volemia em pacientes dialíticos, incluindo a avaliação ultrassonográfica da veia cava inferior (VCI). O alto custo dos ecocardiógrafos e a necessidade de um ecocardiografista para operá-los têm impedido a disseminação da ultrassonografia para avaliar a VCI e, consequentemente, a volemia. Nós hipotetizamos que a classificação volêmica baseada na determinação do diâmetro expiratório da VCI indexado pela superfície corpórea (DVCIi) e o índice de colabamento inspiratório da VCI (ICVCI) realizada por médico nefrologista, sem especialização em ultrassonografia, é similar àquela obtida no mesmo exame realizado por médico especialista em ecocardiografia utilizando um ecocardiógrafo padrão (ECO) ou um equipamento de ultrassom convencional (US). Neste estudo transversal, um ecocardiografista experiente e um nefrologista sem especialização formal em ultrassonografia avaliaram consecutivamente o DVCIi e o ICVCI de 52 pacientes, durante as sessões de hemodiálise. No protocolo I, o nefrologista usou o US e o cardiologista usou o ECO; no protocolo II os aparelhos foram invertidos entre os pesquisadores. Em ambos os protocolos, os coeficientes de Pearson e kappa foram utilizados para avaliar a correlação entre as variáveis contínuas e categóricas, respectivamente. A concordância entre os examinadores foi avaliada pelo Bland-Altman. Obtivemos imagens de boa qualidade da VCI em 96% dos pacientes. As avaliações do DVCIi apresentaram forte correlação em ambos os protocolos (r= 0,88 e 0,84, nos protocolos I e II, respectivamente). A correlação entre as classificações volêmicas foi excelente no protocolo I (kappa = 0,82 e 0,93 pelo DVCIi e ICVCI, respectivamente) e substancial no protocolo II (kappa = 0,77 e 0,75 pelo DVCIi e ICVCI, respectivamente). A concordância entre os examinadores pelo gráfico de Bland-Altman das avaliações de DVCIi foi também muito boa em ambos os protocolos. Nefrologistas sem especialização formal em ultrassonografia usando um US podem avaliar a volemia de pacientes dialíticos através da ultrassonografia de VCI. O mesmo equipamento que já equipa as clínicas de diálise e é utilizado para diversas outras finalidades, como biópsia renal guiada, acesso venoso guiado, avaliação do trato urinário, mapeamento vascular e estudo das fístulas e enxertos, pode ser utilizado para determinação do peso seco. Esperamos assim, reduzir custos e melhorar a qualidade do atendimento dos pacientes dialíticos, através da disseminação da avaliação ultrassonográfica da VCI. / Chronic kidney disease has emerged as a public health problem of substantial proportions, and the number of patients who require renal replacement therapy has been growing over the years. The mortality rate of patients with ESRD remains amazing, and a large part of this mortality is due to cardiovascular disease. The inadequate fluid removal during hemodialysis is a major factor responsible for this unfavorable development. The hypervolemia leads to chronic hypertension, left ventricular hypertrophy, pulmonary congestion and increased rates of hospitalization and mortality. The hypovolemia, moreover, is associated with nausea, vomiting, diminished quality of life, loss of residual renal function, access thrombosis and reduction of dialysis adequacy, due to frequent interruptions of dialysis sessions. Clinically estimated dry weight, defined as the lowest post-dialysis weight at which most excess body fluid will have been removed, is widely used but is poorly predictive of volemic status. Despite the lack of gold standards, related to limitations in accuracy and feasibility, fluid volume has been assessed by using various tools, including ultrasonographic evaluation of the inferior vena cava (IVC). We sought to determine whether a nephrologist with limited ultrasound training can accurately assess the IVC in patients undergoing haemodialysis compared with a cardiologist by using a regular ultrasound system (RUS) or a full cardiovascular ultrasound system (CVUS). In a cross-sectional study, an experienced cardiologist and a nephrologist without formal ultrasound training consecutively measured the indexed IVC expiratory diameter (VCDi) and IVC collapsibility index (IVCCI) of 52 patients during haemodialysis sessions. In protocol I, the nephrologist used an RUS and the cardiologist used a CVUS; in protocol II, the machines were interchanged. In both protocols, Pearson and kappa correlation coefficients were used to evaluate the 11 interobserver correlation of continuous and categorical data, respectively. The interexaminer agreement was determined by the Bland–Altman method. High-quality IVC images were obtained in 96% of the patients. The VCDi measurements showed strong correlation in both protocols (r = 0.88 and 0.84 in protocols I and II, respectively). The volaemic classifications were excellent in protocol I (kappa = 0.82 and 0.93 by the VCDi and IVCCI, respectively) and substantial in protocol II (kappa = 0.77 and 0.75 by the VCDi and IVCCI, respectively). The interexaminer agreement on the VCDi measurements was also very good in both protocols. Ultrasound evaluation of the IVC can be performed by nephrologists without formal training using an RUS to assess volaemic status in patients undergoing haemodialysis. The same equipment that is already being used in dialysis clinics for several other purposes, such as guided renal biopsy, guided venous access, evaluation of the urinary tract, vascular mapping and study of fistulas and grafts can be used to determine the dry weight. We hope reduce costs and improve the quality of care for dialysis patients, through the spread of ultrasound evaluation of the IVC.

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.