Role of ultrasonography in assessing respiratory muscle loss: insights from a cross-sectional study on neurological patients with long-term bed rest with and without tracheostomy.

Abstract

Objective: Prolonged immobilization is the main cause of muscle loss, particularly in patients with tracheostomy. The parasternal intercostal muscle (ICM) and diaphragm are commonly evaluated using ultrasonography; however, the importance of the fifth ICM has been overlooked. We compared the thickness and echogenicity of the second and fifth ICMs and diaphragm in patients with and without tracheostomy to determine the associations with onset duration and other factors and to characterize the respiratory muscle loss.

Patients and methods: This single-center, cross-sectional study compared the thickness and grayscale of respiratory muscles in patients without tracheostomy admitted to a general rehabilitation ward and in patients with tracheostomy admitted to an intensive care rehabilitation ward and correlated them with onset duration, functional capacity, dyspnea, and other parameters.

Results: In patients without tracheostomy, nutritional parameters were associated with delta values of the diaphragm and fifth ICM thickness between the paretic and healthy sides. In contrast, in patients with tracheostomy, the onset duration was associated with grayscale delta values of the second ICM, especially in those with an onset of ≥ 60 days, where the grayscale of the healthy side was significantly lower than that in patients with an onset of <60 days. In patients with and without tracheostomy, the thickness or grayscale of the second or fifth ICMs correlated with the patients' functional independence measure and Borg scores, although this correlation was weak for diaphragm thickness.

Conclusions: In comparison to the diaphragm, the ICM provide a more comprehensive understanding of pulmonary function in patients undergoing extended bed rest, irrespective of the presence of a tracheotomy. Notably, the thickness of the second ICM and the grayscale of the fifth ICM are indicative of dyspnea scores, while the grayscale of the second ICM correlates with scores related to activities of daily living. These indices exhibit differential correlations in patients with and without a tracheotomy. It is imperative that these factors be assessed and compared in clinical practice.