INTRADIALYTIC HYPERTENSION .1.

L.F. is a 64-year-old man with longstanding hypertension and non-insul in-dependent diabetes mellitus leading to end-stage renal disease (ESR D) who has been stable on hemodialysis for two years. His medications include long acting nifedipine 90 mg/day which he takes at night and c lonidine 0.2 mg twice a day, including a morning dose taken prior to d ialysis. His dialysis prescription, delivering a Kt/V of 1.3 is 3 hr w ith an F80 dialyzer at 400 ml/min blood flow through an AV graft. Dial ysate composition is Na of 140 meq/l, K of 2 meq/l, Ca of 3 mEq/l, and NaHCO3 of 37 meq/l at a temperature of 35-degrees-C. The patient's in terdialytic weight gains average 2-3 kg. During five consecutive dialy sis sessions, the patient's blood pressure (BP) rose from a mean predi alysis value of 150/90 to 170/102 after 1 hr and 180/112 after 2 hr on dialysis. Ultrafiltration (UF) was controlled at 800-1000 cc/hr. He r emained asymptomatic, and elevated BP responded rapidly to nifedipine 10 mg PO. There seemed to be nothing unusual about these dialysis trea tments: weight gain was not excessive and predialysis hematocrit varie d between 29% and 31%.