Respiratory sarcopenia screening in dialysis patients: cross-sectional and multicentre study protocol

BACKGROUND

Respiratory sarcopenia is characterized by the weakness of respiratory muscles associated with sarcopenia due to aging or systemic diseases such as chronic kidney disease (CKD). Patients with CKD undergoing dialysis are particularly susceptible to respiratory muscle weakness caused by factors such as fluid overload and electrolyte imbalance. This weakness not only affects ventilation but also impairs oxygen uptake and delivery to muscle tissue, potentially leading to severe sarcopenia. Thus, the objective of this study is to conduct a respiratory sarcopenia screening in patients with CKD undergoing haemodialysis (HD) and peritoneal dialysis (PD).

METHODS

This is an observational, cross-sectional and multicentre study conducted between March 2023 and March 2025. The study was approved by the Research Ethics Committee at two centres. Sarcopenia diagnosis is determined based on low handgrip strength and amount of appendicular skeletal muscle mass, assessed through bioelectrical impedance analysis. Respiratory sarcopenia is diagnosed in patients with sarcopenia who have low inspiratory muscle strength, evaluated through a manovacuometry test. The severity of sarcopenia and respiratory sarcopenia is defined, respectively, by low physical performance (measured using the Short Physical Performance Battery and Timed-Up and Go test) and pulmonary performance (measured through spirometry). Thus, this study will include 81 patients undergoing dialysis (41 on HD and 40 on PD) from three participating centres.

DISCUSSION

The literature has been focused on respiratory function in CKD; however, the relationship with sarcopenia remains understudied. We believe that, similar to appendicular skeleton muscles, the axial skeleton muscles are also likely to weaken with the presence of chronic disease, such as CKD.

Six-minute walk test may be a reliable predictor of peak oxygen uptake in patients undergoing hemodialysis

Background

Cardiorespiratory fitness seems to play an important role in the general health of patients undergoing hemodialysis (HD). However, the prediction of peak oxygen uptake (V̇O2peak) in a clinical setting is not widely adopted for these patients.

Objectives

Evaluate the agreement and reliability between directly and indirectly V̇O2peak measurements in patients undergoing HD.

Methods

This is a cross-sectional study with patients undergoing HD that performed a cardiopulmonary exercise test (CPET) with 5/10 watts incremental load in each minute using a cycle ergometry to directly evaluate the V̇O2peak, and the 6-min walk test (6MWT) in a 30-m corridor to indirect measures it. Both tests were performed on a midweek non-dialysis day. Bland–Altman analysis of agreement limits was used with direct and indirect V̇O2peak values. Intraclass correlation coefficient (ICC) and Cronbach’s Alpha was used to evaluate the reproducibility and reliability between direct and indirect V̇O2peak values.

Results

Twenty-six patients (54.4 ± 14.5 years, 53.8% of male) were evaluated. The V̇O2peak direct mean obtained through CPET was 15.91 ± 5.26 (ml/kg/min), while the indirect mean obtained through 6MWT was V̇O2peak of 14.89 ± 4.21 (ml/kg/min). There was a strong positive correlation between both V̇O2peak values (r = 0.734; p < 0.001). The Bland–Altman analysis demonstrated that the methods agreed with each other (p = 0.103). Also, the ICC (0.829) and Cronbach's Alpha (0.846) showed excellent reproducibility and reliability.

Conclusions

6MWT is a reliable tool for estimating V̇O2peak in patients undergoing HD.

Effects of upper limb exercise programs on the arteriovenous fistula in patients on hemodialysis: A systematic review and meta-analysis

BACKGROUND

The arteriovenous fistula (AVF) is a commonly used vascular access for chronic kidney disease (CKD) patients; exercise interventions may boost its maturation and help in its maintenance. A systematic review and meta-analysis of clinical trials on the effects of upper limb exercise programs on the AVF was conducted.

METHODS

The primary outcomes were draining vein diameter (DVD) and draining vein blood flow rate (DVBFR), and secondary outcomes were handgrip strength (HGS) and brachial artery flow rate (BAFR). Quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

RESULTS

Four studies met the inclusion criteria. When compared to usual care groups, the experimental groups did not improve DVD (mean difference [MD] 0.23, confidence interval [CI] -0.20-0.65). There were significant differences in DVBFR (mL/min) according to the fixed-effect model (MD 141.13, CI 36.84-245.42). HGS (kg) was significantly different between groups (MD 2.95, CI 0.55-5.35), but BAFR (mL/min) was not (MD 91.65, CI -94.72-278.01).

CONCLUSIONS

Although exercise programs did not improve DVD and BAFR, they increased muscle strength and DVBFR. Therefore, experimental exercise programs should be emphasized for AVF maturation and maintenance.Research Registry number: reviewregistry924.