Hypertension in dialysis: pathophysiology and treatment

Hypertension is a major modifiable risk factor for cardiovascular disease, which is the main cause of morbidity and mortality in the dialysis population; therefore, blood pressure (BP) values of <140/90 mmHg (or <160/90 mmHg in the elderly) are recommended. As extra-cellular volume (ECV) expansion is the main pathophysiological determinant of hypertension in dialysis patients, efforts should be made to correctly estimate and achieve the patient's dry body weight. Adequate dialysis treatment time, avoiding the high ultrafiltration rates associated with short treatment times, can greatly help in controlling BP values, at least in part by improving cardiovascular stability. The most promising tool in reducing cardiovascular instability is the use of the conductivity kinetic model, which is easy to apply at each dialysis session without any extra-cost and can also provide information on dialysis dose and vascular access function. On-line monitoring of blood volume (BV) changes has also been used. Convective techniques have long been claimed as providing better cardiovascular stability, compared to diffusive techniques, but solid evidence is still lacking. Anti-hypertensive drugs should be used only when, despite the patient being at his dry body weight, BP values are not adequately controlled. There are no studies specifically addressing which classes of anti-hypertensive drugs provide better organ-protection in dialysis patients. However, the current opinion is that adequate BP control should be guaranteed, irrespective of which classes of drugs are used. Then, ACE inhibitors, angiotensin II receptor antagonists and beta-blockers may be recommended as first choice drugs, given their protective effects in patients at high risk for, or affected by, cardiovascular disease.