Patients with acute respiratory failure (ARF) show changes in skeletal muscle structure and strength. The purpose of this study was to examine the relationship between muscle thickness, echogenicity, and strength in patients with ARF.
Thirteen (6 females, 7 males) patients with ARF participated in the study. Knee extensor strength was measured via a handheld dynamometer and quadriceps images were obtained via ultrasonography at hospital discharge. The ultrasonograms were used to obtain muscle thickness and both mean ± SD echogenicity of the rectus femoris, vastus lateralis, and vastus medialis. Partial correlations, controlling for age, body mass index, and fluid intake were used to describe the relationships among knee extensor strength and echogenicity and muscle thickness.
Knee extensor strength and vastus lateralis SD echogenicity were significantly correlated when controlling for age, body mass index, and fluid intake (r = 0.69, P = .029). Knee extensor strength and vastus lateralis echogenicity were 19.1 ± 8.0 kg and 19.8 ± 5.4 units, respectively. No other correlations between strength and ultrasound measures were found to be significant.
These results show skeletal muscle echogenicity to be significantly correlated with skeletal muscle strength in patients with ARF. As such, it may be useful in identifying muscle weakness in these patients when they are unable or unwilling to perform voluntary strength testing.
This study found that echogenicity of the vastus lateralis, obtained from ultrasonography, was associated with knee extension strength at hospital discharge in patients with acute respiratory failure. As such, ultrasonography may be useful in identifying strength deficits in patients with acute respiratory failure unable to perform volitional strength testing.
Department of Health and Exercise Science, Wake Forest University, Winston-Salem, North Carolina (Dr Berry and Ms Skaggs); Department of Internal Medicine, Wake Forest University School of Medicine, Wake Forest University, Winston-Salem, North Carolina (Drs Files, Campos, and Bakhru); and Department of Internal Medicine, University of Kentucky, Lexington, Kentucky (Dr Morris).
Correspondence: Michael J. Berry, PhD, Department of Health and Exercise Science, Wake Forest University, PO Box 7234, Winston-Salem, NC 27109 (firstname.lastname@example.org).
This study was funded by the Translational Science Center at Wake Forest University.
The authors declare no conflicts of interest.