Shorter delivered dialysis times associate with a higher and more difficult to treat blood pressure.

BACKGROUND Shorter delivered dialysis times are associated with increased all-cause mortality. Whether shorter delivered dialysis times also associate with an increase in blood pressure (BP) and reduce the ability of probing dry weight to lower BP is unclear. METHODS Among patients participating in the Dry-Weight Reduction in Hypertensive Hemodialysis Patients (DRIP) trial, interdialytic ambulatory BP was recorded at baseline, 4 weeks and 8 weeks. Median intradialytic BP was also calculated at each dialysis treatment and associated with the delivered daily dialysis time. RESULTS The median time on dialysis at baseline was 3.6 h per treatment (range 2.5-4.5 h). At baseline, modeled median intradialytic systolic BPs were higher among those who received fewer hours of dialysis. Among subjects who did not have their dry weight probed (control group), the median intradialytic systolic BP continued to be elevated. Probing dry weight (ultrafiltration group) provoked a drop in median intradialytic systolic BP regardless of the delivered dialysis time. However, the reduction in BP was achieved after fewer sessions of dialysis when delivered dialysis was longer in duration. The pattern of change was confirmed using interdialytic ambulatory BP monitoring. CONCLUSIONS Fewer hours of delivered dialysis are associated with a higher systolic BP. Upon probing dry weight, compared with shorter dialysis treatment times, 4 h of delivered dialysis per session provokes reductions in systolic BP over fewer dialysis treatment sessions. Reduction of BP may lag dry-weight reduction when shorter dialysis is delivered.