Quereda 1988.

Methods	Study design: cross‐over RCT Duration of study: not reported Duration of follow‐up: 2 weeks
Participants	Country: Spain Setting: single centre Prevalent patients on HD (age criteria not reported) Number: 8 patients allocated to control and then treatment, or treatment and then control, no attrition Mean age ± SD: 58 ± 9 years Sex (M/F): 2/6 Mean time on dialysis ± SD: 27 ± 22 months None had diabetes mellitus Exclusion criteria: not reported
Interventions	HD regimen Frequency not reported Low‐flux cellulosic dialyser (PAN or CU) Acetate buffer QB and QD not reported Kt/V and URR not reported Treatment (performed in 8 phases) CU dialyser + dialysate [Na+] 133 mM + temp 37 CU dialyser + dialysate [Na+] 139 mM + temp 37 PAN dialyser + dialysate [Na+] 133 mM + temp 37 PAN dialyser + dialysate [Na+] 139 mM + temp 37 CU dialyser + dialysate [Na+] 133 mM + temp 35 CU dialyser + dialysate [Na+] 139 mM + temp 35 PAN dialyser + dialysate [Na+] 133 mM + temp 35 PAN dialyser + dialysate [Na+] 139 mM + temp 35 Duration 6 dialysis sessions for each patient on each phase (192 HD session with dialysate [Na+] 133 mM, 192 HD session with dialysate [Na+] 139 mM)
Outcomes	Outcomes were pooled by dialysate [Na+], since other interventions were identical across groups Outcomes were assessed over the entire period of treatment/observation: Predialysis SBP Intradialytic hypotension: "defined as a fall of systolic BP below 90 mm Hg." IDWG
Notes	Funding source: not reported This research was presented as 2 separate abstracts at EDTA and a local congress, and then published in Int Journal of Artificial Organs SBP values were not reported in a format that could be analysed Extra information was requested from the authors, but none was provided Treatment groups were collapsed by dialysate [Na+], and given the identical sample sizes, the point estimates for each outcomes were calculated as the weighted mean from table 1, and the standard deviations as the square root of the weighted variances from table 1
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomisation clearly stated in published article, but not mechanism of randomisation
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Insufficient information to permit judgement
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Insufficient information to permit judgement
Incomplete outcome data (attrition bias) All outcomes	Low risk	The study appears to be free of attrition bias
Selective reporting (reporting bias)	Low risk	The study appears to be free of reporting bias
Other bias	High risk	Obsolete dialysis practice patterns (cellulosic dialysers, parallel plate dialysers), with a risk of poor external validity (indirectness) No washout