Comparação da avaliação da volemia de pacientes hemodialíticos através de ultrassom de veia cava inferior por ecocardiografista e nefrologista

Abstract

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.