Assessment of diaphragmatic function by ultrasonography: Current approach and perspectives

Abstract

This article reports the various methods used to assess diaphragmatic function by ultrasonography. The excursions of the two hemidiaphragms can be measured using two-dimensional or M-mode ultrasonography, during respiratory maneuvers such as quiet breathing, voluntary sniffing and deep inspiration. On the zone of apposition to the rib cage for both hemidiaphragms, it is possible to measure the thickness on expiration and during deep breathing to assess the percentage of thickening during inspiration. These two approaches make it possible to assess the quality of the diaphragmatic function and the diagnosis of diaphragmatic paralysis or dysfunction. These methods are particularly useful in circumstances where there is a high risk of phrenic nerve injury or in diseases affecting the contractility or the motion of the diaphragm such as neuro-muscular diseases. Recent methods such as speckle tracking imaging and ultrasound shear wave elastography should provide more detailed information for better assessment of diaphragmatic function.

Keywords: Dysfunction; Hemidiaphragm; M-mode; Motion; Paralysis; Speckle tracking imaging; Thickness; Two-dimensional mode; Ultrasound; Ultrasound shear wave elastography.

Figure 1

Diaphragmatic motion recorded by M-mode ultrasonography: measurement of diaphragm excursion, inspiratory time and velocity of contraction. Ordinate in centimeter, abscissa in second. d: Diaphragm excursion; t: Inspiratory time; v: Velocity of contraction.

Figure 2

Use of angle-independent M-mode sonography (arrow) to obtain a perpendicular approach of the right hemidiaphragm: Measurement of excursion (7.14 cm) during deep breathing. Ordinate in centimeter, abscissa in second.

Figure 3

Diaphragmatic motion recorded by M-mode ultrasonography during voluntary sniffing (excursion = 4.51 cm). Ordinate in centimeter, abscissa in second.

Figure 4

Measurement of diaphragm thickness using B-mode ultrasonography: The diaphragm thickening is calculated from the measurement of thickness at both end expiration and end inspiration [here = (4.4-2.6)/2.6 = 69%]. Ordinate in centimeter, abscissa in second.

Figure 5

Recording of the changes in diaphragm thickness during quiet breathing using M-mode tracing (measurement of thickness at end expiration (1 L = 0.25 cm), at end inspiration (2 L = 0.34 cm). Ordinate in centimeter, abscissa in second.

Figure 6

Paradoxical motion (-1.26 cm) recorded by M-mode ultrasonography in patient with left hemidiaphragm paralysis. Ordinate in centimeter, abscissa in second.

Figure 7

Motion recorded during deep breathing in patient suffering from right hemidiaphragm paralysis: Paradoxical motion at the beginning of inspiration (-0.41 cm) terminal excursion in the cranio-caudal direction (+1.5 cm). Ordinate in centimeter, abscissa in second.