Prevalence and risk factors of intra-dialytic hypotension: a 5 year retrospective report from a single Nigerian Centre

Introduction Intra-dialytic hypotension (IDH) is a common complication of haemodialysis that impacts negatively on the patient's quality of life and can induce serious cardiovascular events. Methods Records of all adults who had haemodialysis treatments from Jan 2012-Jan 2016 were reviewed. Socio-demographic data, health status of patient, aetiology of renal disease, clinical and biochemical parameters such as systolic and diastolic blood pressures (SBP and DBP), packed cell volume, were collated using Microsoft Excel. Results The overall prevalence of intra-dialytic hypotension was 8.6%. Of all haemodialysis patients, 45.7% experienced a drop in SBP > 20mmHg, 28.5% required nurses' intervention and 8.6% had symptoms. Diagnosis of obstructive nephropathy (OR: 3.1, CI:1.43-6.60, p = < 0.004) and sepsis (OR: 3.57, CI: 1.31- 9.75, P = 0.013) increased the odds of experiencing IDH. Only 5% of patients with predialysis SBP < 100mmHg developed IDH (OR: 0.12, CI: 0.02-0.93, P = 0.04). Conclusion IDH was common among the patients studied. It was more prevalent among patients with obstructive nephropathy and sepsis; however other traditional risk factors of IDH such as older age and anaemia, were not found to be significantly associated with IDH. Surprisingly, prevalence of IDH was significantly less among patients with pre-dialysis hypotension compared to those without.


Introduction
Haemodialysis is one of the cornerstones of management of chronic kidney disease in Nigeria [1]. Although haemodialysis is a relatively safe procedure, a number of complications may arise which includes intradialytic hypotension (IDH). There is no generally accepted definition for IDH [2]. The Kidney Disease Outcome Initiative (K/DOQI) defined IDH as a decrease in systolic blood pressure by > 20mmHg or a decrease in mean arterial pressure by 10mmHg, associated with symptoms that include abdominal discomfort, yawning, sighing, nausea, vomiting, muscle cramps, restlessness, dizziness, fainting and anxiety [3]. The European Best Practice Guidelines (EBPG) [4] definition is slightly modified to include presence of symptoms and need for nurses intervention. The prevalence of IDH varies from 20-50%, due to inconsistent definitions used across studies. The incidence of IDH is 25% in the US [5]. Amira et al [6] in South-west Nigeria, reported that IDH (defined using EBPG) complicated 8.5% of 1010 haemodialysis treatments. IDH was found to be significantly commoner with initial treatment (25.9%), in older patients, patients with obstructive uropathy (probably due to their older age) and those with low to normal blood pressures. Kuipers et al [7], in a prospective study and applying the EBPG guideline, reported that there was a significant SBP or MAP drop in 77% of the 3818 haemodialysis treatments studied. In same study, 21.4% had intradialytic events and only 6.7% required nursing intervention, resulting in an overall IDH prevalence of 8.5%; prevalence of nurses intervention being the main determinant of overall prevalence. Epidemiological study on IDH and its risk factors are generally scarce in the local literature.
Some of the risk factors of IDH in Chronic kidney patients include: diabetes mellitus, cardiovascular disease (CVD), poor nutritional status and hypoalbuminemia, autonomic dysfunction, severe anemia, age above 65 years and systolic blood pressure < 100mmHg [8] IDH is common and has been attributed variably to body volume depletion, shifting of fluid from extracellular to intracellular space [9], left ventricular hypertrophy and cardiac remodeling particularly in the CKD patients [10]. Patients with chronic kidney disease have defective reactivity of the resistance vessels and capacitance vessels during haemodialysis however; the exact mechanism for this is unknown [11]. In contrast, data from studies involving isolated ultrafiltration and haemofiltration have shown that vascular responses remained intact [12]. IDH impacts negatively on patient's quality of life and can induce cardiovascular events including cardiac arrhythmia, coronary or cerebral ischemic disease [13,14]. Long term effects of IDH includes volume overload due to suboptimal ultrafiltration, use of boluses for resuscitation [3] and inefficient clearance due to adjustments in dialysis prescription to prevent IDH. The result is that some of these patients are forced to seek alternative and sometimes, harmful treatment for their symptoms, since they wrongly believe that haemodialysis either worsens or does not change their clinical state [15]. Some measures recommended to reduce the risk of IDH include: counseling patients to minimise interdialytic weight gain, discontinuing antihypertensives medications prior to dialysis, avoiding the use of long acting vasodilators, avoiding eating before and during procedure and echocardiographic evaluation of ESRD patients [16].
Furthermore treatment related interventions such as: avoiding excessive ultrafiltration, sodium profiling, isolated ultrafiltration and use of some medicines; have been recommended [16]. The aim of this study was to determine the prevalence and risk factors of intradialytic hypotension amongst haemodialysis patients in the study centre.

Methods
A retrospective cross-sectional study carried out in a tertiary hospital

Results
Four hundred and four complete files were included in the data analyses. Majority (55.7%) were males with a sex ratio of 1.25:1.

Competing interests
The authors declare no competing interests.
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Authors' contributions
All the authors have read and agreed to the final manuscript. Tables   Table 1: Aetiology of kidney disease among 404 patients studied