Optimum fluid volume management in people on dialysis is important for both patient experience and outcomes. Both volume overload and depletion are associated with poor outcomes (105-109). Therefore, accurate ‘dry’ or ‘target’ weight assessment is critically important. The clinical assessment of target weight is based on symptoms, skin turgor, peripheral oedema, jugular venous pressure, BP measurement and lung auscultation. It is often a ‘guesstimate’. Several technologies are now available to aid fluid volume assessment including blood volume monitoring, inferior vena caval diameter measurement, lung ultrasound scan and bio-impedance spectroscopy (BIS).
A large, international, observational study and small single centre RCTs suggest that protocolised clinical assessment of volume status in people on haemodialysis may be associated with better clinical and patient reported outcomes (31, 110, 111). This is further supported by the recently published BISTRO trial demonstrating that standardised clinical assessment of fluid volume status is equivalent to standardised clinical assessment augmented by BIS in maintaining residual kidney function in people on haemodialysis (112).
Of the technologies available to assist fluid volume management, BIS is most extensively studied. However, when compared with routine clinical assessment of target weight, none of these technologies have provided consistent benefit in terms of clinical outcomes (106, 113-131). These include two recently published, well-conducted, RCTs (LUST (132)and BISTRO (112)). Furthermore, some of these found increased adverse patient reported outcomes in the technology assisted fluid management group.
Hypertension is a common consequence of fluid overload in dialysis patients. Several observational studies and small trials demonstrate improvement in BP control in both people on peritoneal and haemodialysis (110, 114, 117, 120, 123, 124, 131, 133). However, there are also other studies that fail to show the BP lowering effect of active fluid volume management. Importantly, the BISTRO trial did not demonstrate difference in BP control between protocolised fluid volume management compared with BIS added to protocolised fluid volume management in people on haemodialysis (112). Therefore, there is lack of consistent and firm evidence to support any strong recommendations for fluid volume management to control BP in dialysis patients.