RESUMO
This study investigates the circadian blood pressure variation of non-diabetic chronic hemodialysis (HD) patients on both HD and non-HD days as well as the factors affecting diurnal BP variation. Forty-nine HD patients aged 61.8 +/- 12.9 years who were on daytime HD for 97 +/- 68 months were studied. No significant difference was found in every daytime and nighttime BP between the first (HD) and the second (non-HD) day. However, the ratio nighttime/daytime BP was significantly higher on the second day. Each BP diurnal variability pattern was classified as either Dipper (D: the ratio nighttime/daytime mean BP 0.8-0.9), non-dipper (0.9 < ND < 1.0), or inverted dipper (ID > 1.0). More than 75% of the cases were classified as ND (26 cases) or ID (11 cases). The ultrafiltration rate in D was significantly less than that in ND and ID. The difference of plasma renin activity between pre- and post-HD (dRen) was significantly higher in ID than in D and ND. The amount of dialysis (Kt/V) was found to be significantly correlated with nighttime BP fall. Ultrafiltration, dRen and Kt/V were independent factors for the abnormal BP diurnal variability. In conclusion, the decreased nocturnal BP fall seen in non-diabetic HD patients is associated with increased extracellular fluid even in the patients without overt overhydration, whereas relatively insufficient amount of dialysis (low Kt/V) may be another possible cause. The increased dRen observed only in ID patients may reflect occult cardiovascular damage or functional disturbances in aortic and carotid baroreflexes caused by arterial structural changes.