Measurement of intercostal muscle thickness with ultrasound imaging during maximal breathing

Abstract

[Purpose] Determining the thickness of the intercostal muscle with ultrasound imaging would be a useful parameter in evaluating respiratory muscle activity in patients with tetraplegia and neuromuscular weakness. However, it has not been clarified whether ultrasound imaging can measure changes in intercostal muscle thickness during breathing. This study aimed to measure contractions of the human intercostal muscle in the anterior, lateral, and posterior parts with ultrasound imaging during maximal breathing. [Participants and Methods] The participants were 12 healthy males. Intercostal muscle thickness was measured using ultrasound at rest and at maximal breathing. The measurement sites were the anterior, lateral, and posterior portions of the right intercostal spaces. Statistical analysis was performed using a paired t-test comparing intercostal muscle thickness at rest and maximal breathing. [Results] The thickness of the intercostal muscle showed significant increases in the first, second, third, fourth, and sixth intercostal spaces of the anterior portions. There were no significant differences in the lateral or posterior portions between rest and maximal breathing. [Conclusion] Human intercostal muscle thickness can be measured with ultrasound and increases only in the anterior portions during maximal breathing.

Respiratory muscle ultrasonography: methodology, basic and advanced principles and clinical applications in ICU and ED patients—a narrative review

“…Thickness and inspiratory thickening fraction can be assessed. In healthy subjects, thickening of parasternal intercostal muscles is observed only during maximal efforts [23] and preliminary findings in ICU patients suggest the existence of a dose-response relationship between respiratory load and the parasternal intercostal thickening fraction [24].…”

Investigation of inspiratory intercostal muscle activity in patients with spinal cord injury: a pilot study using electromyography, ultrasonography, and respiratory inductance plethysmography

“…In our previous study, we hypothesized that inspiratory intercostal muscle thickness would increase with increasing inspiratory effort. We used ultrasound to measure thickness changes and confirmed this relationship in healthy adults 7) . However, the association between inspiratory intercostal muscle contraction and inspiratory effort has not been explored in individuals with CSI in a similar manner.…”

“…Parasternal intercostal muscle thickness was measured using static images taken after a maximum inspiration and resting expiration, on the monitor of the diagnostic ultrasound system. These were analyzed using the method applied when measuring the thickness of the parasternal intercostal muscles in healthy individuals 7) , in which parasternal intercostal muscle thickness was measured perpendicular to the axis of contraction, as the distance between the lower edge of the deep fascia and the upper edge of the superficial fascia (precision: 0.1 mm) in the center of the area where the fibers of the deep and superficial fascia were observed to run parallel in the images. Intercostal muscle thickness changes (resting expiration and maximum inspiration) were calculated and compared with IC for each case to check the relationship.…”

Ultrasonographic assessment of parasternal intercostal muscles during mechanical ventilation

“…Given the preliminary nature and the weak correlation of the results, this topic deserves to be explored more thoroughly. A recent study by Yoshida et al [26] used ultrasound to assess whether human parasternal intercostal muscle thickness increased during vigorous breathing efforts (the maximal inspiratory level using an inspiratory resistance loading device). The images obtained showed an increase in muscle thickness only in the anterior portion of the intercostal space during maximal breathing, whereas no significant differences could be detected in the lateral and posterior portions.…”

“…Accurate muscle measurement depends not only on operator skills (e.g., measurement location, probe angulation), but also on technical aspects related to ultrasound physics and patient characteristics. While in general ultrasound seems to be a reliable technique, comparing individual patient results must be done with a degree of caution and only after adequate training, as small observer-dependent variations will affect results [ 24 – 26 ]. The aim of this review is to define the role of the intercostal muscles and their ultrasound evaluation during MV.…”