title: Characterising haemodynamic stress during haemodialysis using the extrema points analysis model.
abstract: OBJECTIVE
  It is becoming recognised that the process of haemodialysis (HD) itself induces circulatory stress that could be implicated in the observed higher rate of end-organ damage. We aimed to study the haemodynamic performance during HD using the extrema points (EP) analysis model, and to examine the determinants of the model and its relation to circulatory stress.
  
  
  METHODS
  63 incident HD patients were studied. Mean arterial blood pressure (MAP) EP frequencies and baroreflex sensitivity during HD were computed for continuous non-invasive haemodynamic monitoring. Pulse-wave velocity as a measure of arterial stiffness was performed. High-sensitivity troponin-T was also measured.
  
  
  RESULTS
  The time of each dialysis session was divided into four quarters. Repeated measures ANOVA of the MAP EP frequencies for all subjects during HD demonstrated a gradual significant increase reaching peak levels at the third quarter of dialysis time and remaining at that peak during the fourth quarter (F(3,171228) = 392.06, p < 0.001). In multivariate regression, lower baroreflex sensitivity was the only independent predictor of higher MAP EP frequencies (β = -0.642, p = 0.001, adjusted R(2) for the whole model = 0.385). In linear regression analysis, higher MAP EP frequencies were associated with higher troponin-T levels (β = 0.442, p = 0.002, R(2) = 0.19, B = 103.29, 95% CI 38.88-167.70).
  
  
  CONCLUSIONS
  The EP analysis model using MAP is a novel functional haemodynamic measure that can represent and quantify circulatory stress during HD. This measure seems to be determined by the integrity of the autonomic function in HD and could represent the link between circulatory stress and end-organ damage in HD patients.
authors.affiliation: Division of Medical Sciences, School of Medicine, University of Nottingham, Derby, UK.
authors.forename: Mohamed Tarek
authors.initials: MT
authors.lastname: Eldehni
authors.forename: Aghogho
authors.initials: A
authors.lastname: Odudu
authors.forename: Christopher William
authors.initials: CW
authors.lastname: McIntyre
mesh_terms: D005260:Female; D006439:Hemodynamics; D006801:Humans; D007676:Kidney Failure, Chronic / Q000503:physiopathology* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D006435:Renal Dialysis; D013312:Stress, Physiological