High magnesium dialysate does not improve intradialytic hemodynamics or abrogate myocardial stunning

Abstract

Background: Hemodialysis (HD) induces myocardial stunning and is associated with adverse cardiovascular outcomes. Intradialytic hypotension is a modifiable determinant of myocardial stunning. Magnesium (Mg) is reported to be valuable in maintaining intradialytic blood pressure, which potentially would protect against demand myocardial ischemia. This study aimed to compare high vs. low dialysate Mg effects on intradialytic hemodynamics and HD-induced myocardial stunning. Methods: Twenty stable prevalent HD patients entered a randomized cross-over trial of low (0.5 mmol/L) vs. high (1.0 mmol/L) dialysate Mg. Patients were studied after 2 weeks of standard HD with each Mg concentration. Serial echocardiography assessed myocardial stunning, measured by left ventricular regional wall motion abnormalities (RWMAs). Continuous intradialytic hemodynamics were measured noninvasively using thoracic bioimpedance. Findings: Median predialysis serum Mg was higher with high dialysate Mg (1.45[1.29-1.55] vs. 1.03 [0.98-1.1] mmol/L, P < 0.0001). There was no significant difference in maximum intradialytic reduction in systolic BP. There was no significant difference in stroke volume, total peripheral resistance, and cardiac output. Overall ventricular global longitudinal strain (GLS) (as a sensitive marker of contractile function) was higher before dialysis in high Mg group, but there was no difference in GLS at peak stress. However, we showed a significant correlation between Mg changes and GLS changes, r = −0.47, P = 0.02. There was no difference in mean number of peak stress RWMAs per patient (4.0 AE 2.2 vs. 4.3 AE 2.9, P = 0.5). Ultrafiltration volume, a critical determinant of stunning, was not different between high and low dialysate Mg studies (1.35[0-3.3] vs. 1.5[0-2.8], P = 0.49). Discussion: Manipulation of magnesium by altering dialysate magnesium concentration does not influence intradialytic hemodynamic response or HD-induced myocardial stunning in the short term. However, decreasing Mg changes appears to decrease GLS changes.

Magnesium Administration in Chronic Kidney Disease

“…After 6 months of an increased Mg dialysate concentration of 0.75 mmol/L, a statistically significant and likely clinically relevant reduction in systolic blood pressure was observed (−12.96 mmHg [95% CI −24.71, −1.22]), without significant change in diastolic blood pressure [ 46 ]. The sparse studies investigating the effects of increasing Mg dialysate concentration on intradialytic hemodynamics were small, short-term (2 to 4 weeks), and had conflicting results [ 82 , 99 ]. Neither of the two RCTs investigating endothelial function observed an effect of increasing dialysate Mg concentration or oral supplementation [ 26 , 46 ].…”

“…A recent Japanese, two-year observational study in hemodialysis patients demonstrated an inverse association for Mg concentration and the risk of hip fractures, with an OR 0.96 [0.94–0.99] per 0.1 mmol/L increase of plasma Mg [ 104 ]. Although, theoretically, an extreme increase of dialysate Mg is imaginable, only cautious dialysate increases are investigated due to the risk of fast intra- and extracellular electrolyte shifts during as well as between dialysis sessions [ 44 , 46 , 99 , 105 ]. Symptomatic hypermagnesemia, generally only seen in people with serum Mg concentrations of 1.6 to 2.0 mmol/L or above, is very rare, usually iatrogenic, and can follow decreased renal excretion, intra- to extracellular compartment shifts, and most frequently from excessive intake [ 106 ].…”

Monitoring of ionized magnesium in hemodialysis patients: A useful tool to allow a personalized prescription of dialysate composition

“…A randomized 4-week crossover study conducted by Del Giorno et al [41] showed that increasing dialysate Mg from 0.5 to 0.75 mmol/L improved vascular stiffness of subjects undergoing maintenance hemodialysis. A 2week randomized crossover study of low (0.5 mmol/L) versus high (1 mmol/L) dialysate Mg conducted by Jefferies et al [42] failed to demonstrate an improvement of intradialytic hemodynamics or myocardial stunning. Nevertheless, the authors found a significant correlation between Mg changes during the session and changes in global longitudinal strain.…”

Individualising / personalizing hemodialysate composition

“…Dialysate [K] analysis is necessary to preserve "K homeostasis" because K exclusion is entirely reliant on gradients among pre-dialysis plasma as well as dialysate [K] (along with HD time & K dialysance). Bleyer et al (2006) [8] discussed the impact of K in HD and found that the massive proportion of unexpected deaths on the 1 st day of the week (at the completion of long interdialysis time), when plasma [K] is usually higher, shows how important it is to know that high pre-dialysis plasma [K] raises the chances of life-threatening occurrences. Kovesdy and colleagues (2007) [9] presented that patients with greater pre plasma [K] were more likely to die when they used a relatively high dialysate [K].…”

“…In a large observation -based research, Jefferies & McIntyre (2010) said that the baseline magnesium in the recommended dialysate [Mg] had only a weak connection with the magnesium in the plasma [Mg]. This shows that other elements, like magnesium from diet, nutritional supplements including antacids & phosphate binders, and possibly even laxatives, may be significant as well.…”