Abstract: Objective  To explore the relationship between the blood pressure and pumped blood flow rate and the blood flow rate in fistula (access flow, Qa) during hemodialysis sessions.  Method  The electronic sphygmomanometer and hand-held Doppler ultrasound apparatus were used to measure blood pressure and Qa before hemodialysis, within 30 minutes of the hemodialysis session at blood flow rate of 200 ml/min, 250 ml/min and 300 ml/min, at the 2nd hour and 4th hour (within 20 minutes before end of the sessions) of the hemodialysis session.  Result  A total of 104 maintenance hemodialysis patients were enrolled in this study. We found that ①Qa and the change rate of mean arterial pressure (MAP) were positively correlated both at the first stage of hemodialysis (0～2nd hours; r=0.447, P<0.001) and the second stage of hemodialysis (2nd～4th hours; r=0.355, P<0.001); ②MAP and Qa were statistically different between the values before dialysis, at the 2nd hour of dialysis, and at the 4th hour of dialysis (F=77.068 and 32.887, P<0.001);  ③MAP decreased by 14.593 mmHg (95% CI 11.613～17.572, P<0.001) and Qa decreased by 105.853 ml/min (95% CI 72.757～138.948, P< 0.001) at the 4th hour of dialysis, as compared those before dialysis; ④the linear fitting between Qa change rate (y) and MAP change rate (x) derived an equation of y=0.75x (P=0.000); and ⑤the difference between Qa and increased pumped blood flow rate had no statistical significance (F=2.352, P=0.099).  Conclusions  During hemodialysis sessions, Qa decreases along with the decrease of MAP; when MAP decreases by 10%, Qa will decrease by 7.5%. Qa is unrelated to the pumped blood flow rate.

Key words: Hemodialysis, Doppler ultrasound, Mean arterial pressure, Access flow