Management of intradialytic hypertension: old problem, old drug?

Of the patients beginning with dialysis, 60–85% of them may account for hypertension, and dialysis alone is capable of controlling hypertension in over 50% of these patients [1]; resistant hypertension and paradoxical blood pressure (BP) elevation during dialysis are possible but relatively infrequent complications [1]. Nevertheless, there is no widely accepted definition of intradialytic hypertension [2]. Several definitions, mostly arbitrary, have been used such as any increase in mean arterial BP of 15 mmHg or more during or immediately after hemodialysis, hypertension during the second or third hour of dialysis after significant ultrafiltration has taken place, or an increase in BP that is resistant to ultrafiltration, with post-ultrafiltration BP exceeding the pre-ultrafiltration BP in more than half of the sessions [2]. Thus, the prevalence of intradialytic hypertension, in consideration with the different definitions, has shown wide variations, from 5 to 15% [2]. We report a case of a 70-year-old woman with a personal medical history including a long-standing smoking habit, type-2 diabetes mellitus with diabetic nephropathy, cerebral vascular disease, coronary artery disease, previous myocardial infarction treated with PTCA and stenting. Forty-one weeks before, she had started chronic dialysis therapy three times a week, performed by artero-venous fistula on an afternoon shift (13:00–18:00 hours). Some of the details of the dialysis treatment are bicarbonate dialysis, duration 3.5 h, average weekly body weight gain 3.3 kg, hourly decrease 9 mm Hg, blood flow 300 ml/min. Pharmacologic therapy included clopidogrel 75 mg/day, metoprolol 50 mg b.i.d., sustained-release isosorbide-5mononitrate 50 mg/day, nifedipine gastrointestinal therapeutic system (GITS) 60 mg/day, ramipril 10 mg/day, and clonidine transdermal (1 TTS1 system/week). The patient showed significant increase in BP levels, especially during the second hour of dialysis, not responding to several drug schedules, e.g., extradoses of nifedipine, amlodipine, and clonidine. Only the introduction in therapy of the vasodilatator minoxidil (Loniten , Pharmacia & Upjohn SpA) allowed a successful control and stabilization of the paradoxical BP increase (Table 1). A first point of discussion could be the lack of use of diuretics. In advanced renal failure, sodium imbalance is becoming positive, and the extracellular volume (ECV) expands. In patients with chronic kidney disease, especially in the case of poor adherence to salt restriction, diuretics play an important role [3]. However, this is not always the case for dialysis patients. The concept of controlling BP by achieving the lowest possible ECV has been termed as ‘‘dry weight’’, the post-dialysis weight at which the patient is and remains normotensive until the next dialysis despite the interdialytic fluid retention without anti-hypertensive medication [4]. Dry weight is usually assessed using the clinical method [4]. Useful information include: (1) medical history (dietary habits, salt excess) and presence/ absence of symptoms of volume overload; (2) clinical signs: blood pressure (measured lying, sitting, and standing), weight, central venous pressure, presence of edema; E. Rizzioli Modulo di Nefrologia, Unità Operativa di Medicina Interna, Ospedale del Delta, Azienda U.S.L. di Ferrara, Ferrara, Italy