Blood Pressure Response to Uncomplicated Hemodialysis: The Importance of Changes in Stroke Volume

Abstract

Background: The cause of blood pressure (BP) changes during uncomplicated hemodialysis (HD) has not been fully investigated. Controversy exists whether changes in BP result from changes in stroke volume (SV) or total peripheral resistance (TPR). Methods: We investigated 19 patients using continuous BP monitoring (Portapres^®) and subsequent Modelflow^® analysis, yielding continuous SV, cardiac output (CO) and TPR values. Blood volume (BV) monitoring was also performed. For each patient, the sensitivity index (SI) was calculated. The SI is the slope of the curve depicting the relationship between the systolic BP (SBP) response and the BV response. The patients were divided into two groups: group A had an SI >1 which means a decrease in SBP in response to BV change, and group B had an SI <1. In these patients, SBP remained stable despite a BV change. Results: Baseline characteristics and baseline values of all parameters were similar between the groups. In group A, SBP decreased by 25 ± 19 mm Hg and in group B the SBP increased by 5.0 ± 29 mm Hg (p < 0.05), while BV change was similar (10.6 ± 4.9 and 11.2 ± 4.2%, respectively). The difference in SBP response was caused by a different SV response (group A –44 ± 16% and group B –26 ± 18%, p = 0.04), while the TPR response was similar (71 ± 27% in group A vs. 59 ± 58% in group B). Conclusion: Patients responding with a BP decrease to BV reduction during uncomplicated HD differ in their SV response from patients with a stable BP.

Hemodialysis Reduces Augmentation Index but Not Aortic or Brachial Pulse Wave Velocity in Dialysis-Requiring Patients

“…A decrease in the amount of the incident wave reflected at peripheral sites may be a predominant mechanism. Correlation analysis revealed significant associations between the changes in heart rate-adjusted AIx during the dialysis session at both time-points studied and the changes in central aortic SBP and PP; thus BP-lowering following fluid removal, which is a well-documented effect of hemodialysis [23,24], could be involved in reduction in wave reflections from the periphery. It is known that depending on the metabolic needs of each peripheral tissue, the peripheral vascular beds have the property of autoregulation; vasoconstriction or vasodilatation at the level of precapillary sphincter is used to modify blood supply and therefore oxygen and metabolic substance delivery to the tissues.…”

“…It is known that depending on the metabolic needs of each peripheral tissue, the peripheral vascular beds have the property of autoregulation; vasoconstriction or vasodilatation at the level of precapillary sphincter is used to modify blood supply and therefore oxygen and metabolic substance delivery to the tissues. A relatively acute fall in BP following fluid removal during hemodialysis may lead to peripheral vasodilatation; indeed previous studies have shown the hemodialysis procedure to be associated with reduction in total peripheral resistance [23,24,25]. This vasodilatation may acutely lead to modification of the reflecting properties of the peripheral sites and thus, reduction in the amplitude of the reflected wave.…”

What Is the Meaning of Increased Myocardial Injury Enzymes during Hemodialysis? A Tissue Doppler Imaging Study

“…The pathophysiology of these adverse effects is an important new field of study for nephrology because there is more and more evidence suggesting that subclinical myocardial ischemia is induced by HD and that this is a common phenomenon. HD patients are susceptible to myocardial ischemia due to the hemodynamic changes occurring during HD [7,8]. Silent ST segment depression is seen between 15 and 45% in this patient group [9,10].…”

Hemodialysis-Induced Cardiac Dysfunction Is Associated with an Acute Reduction in Global and Segmental Myocardial Blood Flow

“…Short intermittent HD treatments exert significant hemodynamic effects, and 20 to 30% of treatments are complicated by intradialytic hypotension (7,8). In conjunction with this, HD patients are particularly susceptible to myocardial ischemia.…”