Intra-dialytic hypotension: Identifying patients most at risk.

Background: Intra-dialytic hypotension (IDH) remains a frequent but serious complication of haemodialysis. Methods: We performed a retrospective observational analysis of our prevalent dialysis population extracting data from an online database. Results: Four hundred and thirty-two patients underwent 21 consecutive outpatient dialysis sessions during the study period: Of the 9,072 dialysis sessions studied, 438 were complicated by episodes of IDH (4.8%). 266/432 patients were asymptomatic whilst 166/432 experienced at least one episode of IDH. Symptomatic patients had significantly lower pre-dialysis systolic blood pressures (137 mmHg compared with 146 mmHg p < 0.0001) and demonstrated a greater per cent drop in their systolic blood pressure (delta systolic) before and after dialysis (9.7% vs. 4.1% p < 0.0001). Patients taking either a single or no antihypertensive agents had a significantly higher delta systolic than those on two or more anti-hypertensive agents (7.6% vs. 2.2% p < 0.01) and were almost 50% more likely to suffer from IDH (RR = 1.48, p = 0.017). Using logistical regression we identified pre-dialysis systolic blood pressure and delta systolic blood pressure as strong predictor variables for IDH (p < 0.0001). We constructed amodel able to calculate the risk of an individual patient suffering with IDH using delta systolic and pre-dialysis systolic blood pressure. A ROC analysis suggests this to be an accurate model (AUC = 0.79). Conclusion: Delta systolic blood pressure is clinically useful in identifying patients most at risk of IDH. Anti-hypertensive medication use is associated with a lower delta systolic and a lower risk of IDH.