POOR AGREEMENT BETWEEN PHYSICAL EXAMINATION AND BIOIMPEDANCE SPECTROSCOPY IN THE DETECTION OF HYPERVOLEMIA IN HAEMODIALYSIS PATIENTS

Abstract BACKGROUND AND AIMS Assessment of dry-weight among patients on haemodialysis is challenging in the absence of reliable markers to define overhydration (OH) [1, 2]. This study aimed to explore the value of two simple clinical signs, the presence of pedal oedema and crackles at pulmonary auscultation, in diagnosing hypervolemia, using the bioimpendence spectroscopy as a more objective method. METHOD In a cohort of 107 asymptomatic dialysis patients, the volume status was assessed with physical examination and bioimpedance spectroscopy shortly before the mid-week dialysis session [3]. Patients were also asked to perform home blood pressure (BP) monitoring with a validated, automatic device (HEM-705, Omron, Healthcare) [4] for 1 week in order to determine their BP control status. RESULTS Patients within the high tertile of pre-dialysis OH had longer dialysis vintage, lower serum albumin and higher home systolic BP, despite the more aggressive treatment with a higher average number of antihypertensives daily. In receiver-operating-characteristic (ROC) curve analysis, pedal oedema [area under curve (AUC): 0.534, 95% confidence interval (95% CI) 0.416–0.651] and pulmonary crackles (AUC: 0.551; 95% CI 0.432–0.671) had limited accuracy in the diagnosis of pre-dialysis OH > 2.2 L. The agreement of pedal oedema (Cohen's k-coefficient: 0.065) and pulmonary crackles (Cohen's k-coefficient: 0.122) with bioimpedance spectroscopy in the detection of hypervolemia was poor. In multivariate linear regression analysis, longer dialysis vintage (β: 0.306; P<0.001) and higher home systolic BP (β: 0.287; P<0.01) were the two factors that were independently associated with pre-dialysis OH. CONCLUSION This diagnostic-test study showed that among asymptomatic hemodialysis patients, pedal oedema and pulmonary crackles in physical examination had limited discriminatory power in the detection of hypevolemia, as assessed more objectively with the method of bioimpedance spectroscopy.