P114 A STUDY INTO THE PREVELANCE OF INTRADIALYTIC HYPERTENSION IN A UK HAEMODIALYSIS POPULATION Talbot B, Goodache R, Ford M, Lawman S Royal Sussex Kidney Unit, Brighton. INTRODUCTION: In the UK 16,000 people are dependent upon haemodialysis. The greatest burden of morbidity and mortality for haemodialysis patients is cardiovascular disease, which accounts for approximately 50% of all deaths. Fluctuations in blood pressure are one of the most common complications that occur in these patients. Most commonly hypotension, however intradialytic hypertension (IDH) can also occur. Although this is relatively poorly understood recent studies suggest IDH may affect as many as 15% of the dialysis population and has been linked to significant adverse outcomes, mainly cardiovascular disease. Currently no studies have looked at the scale of the problem or its impact on the UK haemodialysis population. The aim of this study was to evaluate the prevalence of IDH in a cohort of patients attending regular dialysis sessions at a single dialysis unit and to investigate whether any modifiable risk factors could be identified. METHOD: Ethical approval was obtained for a cross-sectional cohort study designed to include all adult patients dialysing as an outpatient, at a single dialysis unit, excluding those dialysing for less than 30 days and those with an acute illness (153 eligible patients). Blood pressure recordings were taken every 15minutes for 3 dialysis sessions, with the first just before commencing dialysis and the last 15minutes after completion. The 3 dialysis sessions included one session after the longer 2 day break. The patient’s age, serum albumin, target weight, pre and post dialysis weight, volume of ultrafiltration and blood pressure medications were also recorded. 2 definitions of intradialytic hypertension were used: 1 ≥10mmHg increase in systolic blood pressure (SBP) from pre to post dialysis, for two or more sessions. 2. The maximum change in systolic blood pressure during a session was ≥10mmHg, for two or more sessions. RESULTS: 103 Patients completed the study (63% male). The prevalence of IDH in the haemodialysis population of this study was 13.6% and 21.4% using definitions 1 and 2 respectively. Patients experiencing IDH had a significantly lower starting BP with statistical significance for each definition (P<0.003 for Definition 1 and P<0.000001 for Definition 2 when compared with the group that didn't experience IDH on any occasion). Patients experiencing IDH also had a statistically significant higher end dialysis BP for both definitions (P<0.00002 for Definition 1 and P<0.003 for Definition 2 when compared with the group that didn't experience IDH on any occasion). Albumin levels were lower in the IDH group but only found to be significant under definition 2. The median number of anti-hypertensive medications in the patients with IDH was 2, compared with 1 in those without. This was statistically significant when compared to patients with no IDH under both definitions (P<0.01 and P<0.02 respectively). CONCLUSION: This study has identified IDH to be prevalent in a significant proportion of the haemodialysis population in this UK dialysis center. We have found a significant association with lower pre-dialysis BP, higher post-dialysis BP and increased use of anti-hypertensive medications, which is in concordance with previous non-UK based studies. It has been postulated that the relationship between anti-hypertensive medication and IDH may be related to the variable removal of different medications via the dialysis process. We plan to perform further analysis of our results to determine if that is the case in our population and to determine the modifiable risk factors for IDH. Given the relationship that has been found between IDH and adverse clinical outcomes, specifically cardiovascular morbidity, there is an urgent need for further research into this phenomenon.