A Higher Concentration of Dialysate Magnesium to Reduce the Frequency of Muscle Cramps: A Narrative Review

The pathophysiology of leg cramping during dialysis and the use of carnitine in its treatment

Leg cramping is a common side effect of hemodialysis, and this is frequently treated by the administration of carnitine, but this is not effective in every patient. Alkalosis is a key component of the etiology of leg cramping during hemodialysis sessions. This is mediated through the binding of calcium ions to serum albumin, which causes hypocalcemia, and an increase in the release of calcium ions from the sarcoplasmic reticulum. Normally the calcium pump on the sarcoplasmic reticulum consumes ATP and quickly reuptakes the released calcium ions, which rapidly stops excessive muscle contractions. Thus, carnitine deficiency results in prolonged muscle contraction because of ATP depletion. However, during ATP production, carnitine is only involved up to the stage of acyl-CoA transport into mitochondria, and for the efficient generation of ATP, the subsequent metabolism of acyl-CoA is also important. For example, β-oxidation and the tricarboxylic acid cycle may be affected by a deficiency of water-soluble vitamins and the electron transport chain requires coenzyme Q10, but statins inhibit its production. The resulting accumulation of excess long-chain acyl-CoA in mitochondria inhibits enzymes involved in energy production. Thus, carnitine administration may be used more effectively if clinicians are aware of its specific physiologic roles.

Patient Partner Perspectives Regarding Ethically and Clinically Important Aspects of Trial Design in Pragmatic Cluster Randomized Trials for Hemodialysis

BACKGROUND

Cluster randomized trials (CRTs) are trials in which intact groups such as hemodialysis centers or shifts are randomized to treatment or control arms. Pragmatic CRTs have been promoted as a promising trial design for nephrology research yet may also pose ethical challenges. While randomization occurs at the cluster level, the intervention and data collection may vary in a CRT, challenging the identification of research participants. Moreover, when a waiver of patient consent is granted by a research ethics committee, there is an open question as to whether and to what degree patients should be notified about ongoing research or be provided with a debrief regarding the nature and results of the trial upon completion. While empirical and conceptual research exploring ethical issues in pragmatic CRTs has begun to emerge, there has been limited discussion with patients, families, or caregivers of patients undergoing hemodialysis.

OBJECTIVE

To explore with patients and families with experience of hemodialysis research the challenges raised by different approaches to designing pragmatic CRTs in hemodialysis. Specifically, their perceptions of (1) the use of a waiver of consent, (2) notification processes and information provided to participants, and (3) any other concerns about cluster randomized designs in hemodialysis.

DESIGN

Focus group and interview discussions of hypothetical clinical trial designs.

SETTING

Focus groups and interviews were conducted in-person or via videoconference or telephone.

PARTICIPANTS

Patient partners in hemodialysis research, defined as patients with personal experience of dialysis or a family member who had experience supporting a patient receiving hemodialysis, who have been actively involved in discussions to advise a research team on the design, conduct, or implementation of a hemodialysis trial.

METHODS

Participants were invited to participate in focus groups or individual discussions that were audio recorded with consent. Recorded interviews were transcribed verbatim prior to analysis. Transcripts were analyzed using a thematic analysis approach.

RESULTS

Two focus groups, three individual interviews, and one interview involving a patient and family member were conducted with 17 individuals between February 2019 and May 2020. Participants expressed support for approaches that emphasized patient choice. Disclosure of patient-relevant risks and information were key themes. Both consent and notification processes served to generate trust, but bypassing patient choice was perceived as undermining this trust. Participants did not dismiss the option of a waiver of consent. They were, however, more restrictive in their views about when a waiver of consent may be acceptable. Patient partners were skeptical of claims to impracticability based on costs or the time commitments for staff.

LIMITATIONS

All participants were from Canada and had been involved in the design or conduct of a trial, limiting the degree to which results may be extrapolated.

CONCLUSIONS

Given the preferences of participants to be afforded the opportunity to decide about trial participation, we argue that investigators should thoroughly investigate approaches that allow participants to make an informed choice regarding trial participation. In keeping with the preference for autonomous choice, there remains a need to further explore how consent approaches can be designed to facilitate clinical trial conduct while meeting their ethical requirements. Finally, further work is needed to define the limited circumstances in which waivers of consent are appropriate.