Measuring the Loss of Skeletal Muscle Mass in the Hospitalized Patient With the Diagnosis of COVID-19

The COVID-19 pandemic is having a devastating global impact, and older adults who experience it are at higher risk of death from the disease. However, survivors of the disease have a greater risk of suffering from pathologies such as sarcopenia, which is more frequent in younger adults and with greater severity of the disease.

Sarcopenia is present in 5-13% of people between 60 and 70 years old and in 11-50% of the population over 80 years of age. The diagnosis of sarcopenia has advanced in recent years by establishing homogeneous criteria in different consensuses that necessarily combine two elements: generalized loss of strength accompanied by loss of skeletal muscle mass. Today there are three consensuses for the diagnosis of sarcopenia: the international (IWGS), the European (EWGSOP), and the most recent from a US cohort (FNIH). In all of them, the measurement of skeletal muscle mass constitutes one of the two diagnostic criteria.

The main methods to measure this muscle loss that are established are imaging techniques (computerized tomography (CT), magnetic resonance imaging (MRI), dual-energy X-ray absorptiometry (DEXA) and ultrasound.

The most common ultrasound measurements used for this purpose are the muscle thickness (cm) at the point of the ultrasound path of maximum muscle thickness, the cross-sectional area (area calculated by the basic software at the point of maximum muscle thickness), and the pennation angle (angle formed between deep muscle fascia and muscle fibers). The first two measurements can be made on several long muscles, while the pennation angle is usually made primarily on the medial gastrocnemius (internal twin) muscle. They are easy to obtain, bloodless, and reproducible measurements.

Research efforts at this point in the pandemic should focus on the longer-term consequences of the disease, sequelae such as sarcopenia in patients who have suffered from COVID-19. At the same time, clinicians must become increasingly aware of the condition and its measurement integrated into clinical practice. The knowledge provided by studies such as the one presented will allow the development of specific interventions.

The risk of sarcopenia should be considered when carrying out a risk / benefit assessment of the established treatment (for example, dexamethasone), and considering a multidisciplinary treatment that includes dietary inputs.