Ecografía POCUS: una herramienta para la detección y seguimiento de sarcopenia en diálisis peritoneal

The prevalence of sarcopenia varies between 1.5% and 68% among patients with chronic kidney disease (CKD). This wide range is due to the different diagnostic tools and the cut-off points used. Early diagnosis and intervention of sarcopenia are essential because of its association with poorer quality of life (QoL), higher hospitalization rates, and adverse events. The European Working Group on Sarcopenia in Older People (EWGSOP2) consensus review suggests ultrasound as an emerging tool to quantify muscle mass. Our objective is to describe the prevalence of sarcopenia risk in peritoneal dialysis (PD) and the utility of ultrasound in our setting.

Material and methods

We conducted an observational study in prevalent PD patients at the Puerta de Hierro University Hospital between January and October 2023. Clinical, efficacy, analytical and nutritional parameters were collected, along with functional performance measured by SPPB, frailty (FRAIL scale), risk of malnutrition (MIS scale), bioimpedance and estimation of appendicular skeletal muscle mass using Lin's formula. Ultrasound measurement of supramuscular fat, axes (X and Y) and the area of the rectus femoris muscle of the quadriceps were also included, adjusted for height and body surface area. We classified patients at risk of sarcopenia based on handgrip strength according to EWGSOP2 criteria, adjusted for sex. This study was approved by the Ethics Committee of Puerta de Hierro University Hospital (No. 16/2023).

Results

We evaluated 38 patients, with a mean age of 65.4 years (SD 14.9), 65.8% were male. 52.6% had a reduced lean tissue index (LTI) and 23.7% had a reduced fat tissue index (FTI), with a mean phase angle (AF) of 4.5 (SD 1.1). We classified 42.1% as patients at risk of sarcopenia based on handgrip strength. They were older, had more comorbidities, poorer nutrition according to the MIS scale, and showed worse scores on frailty and functional capacity. Similary, they had a lower LTI, lower appendicular skeletal muscle mass, and lower quadriceps muscle thickness (Y axis 8.5 mm [SD 2.4] vs. 11.8 mm [SD 3.3], P = 0.002). Patients at risk of sarcopenic had lower phosphorus levels and higher C-reactive protein levels. The predictive capacity of ultrasound for classifying patients at risk of sarcopenia was AUC 0.78 (0.64-0.93) for Y axis, similar to those obtained with the LTI and AF of bioimpedance.

Conclusions

Sarcopenia risk is highly prevalent in PD and is related to age, comorbidity, malnutrition and inflammation in patients. Ultrasound is an accessible, safe, low-cost and easy-to-use tool at the bedside. This method helps us to quantify muscle mass and assess its quality. We propose the thickness of the rectus femoris muscle (Y axis) as the best complementary parameter given its good correlation with bioimpedance and its diagnostic value for sarcopenic risk. Our experience will serve as a basis for future studies that allow us to define specific cut-off points in PD and design monitoring and intervention protocols.