Real-time shear wave ultrasound elastography: a new tool for the evaluation of diaphragm and limb muscle stiffness in critically ill patients

Abstract

Background: Muscle weakness following critical illness is the consequence of loss of muscle mass and alteration of muscle quality. It is associated with long-term disability. Ultrasonography is a reliable tool to quantify muscle mass, but studies that evaluate muscle quality at the critically ill bedside are lacking. Shear wave ultrasound elastography (SWE) provides spatial representation of soft tissue stiffness and measures of muscle quality. The reliability and reproducibility of SWE in critically ill patients has never been evaluated.Methods: Two operators tested in healthy controls and in critically ill patients the intra-and inter-operator reliability of the SWE using transversal and longitudinal views of the diaphragm and limb muscles. Reliability was calculated using the intra-class correlation coefficient and a bootstrap sampling method assessed their consistency. Results: We collected 560 images. Longitudinal views of the diaphragm (ICC 0.83 [0.50-0.94]), the biceps brachii (ICC 0.88 [0.67-0.96]) and the rectus femoris (ICC 0.76 [0.34-0.91]) were the most reliable views in a training set of healthy controls. Intra-class correlation coefficient for inter-operator reproducibility and intra-operator reliability was above 0.9 for all muscles in a validation set of healthy controls. In critically ill patients, inter-operator reproducibility and intra-operator 1 and 2 reliability ICCs were respectively 0.92 [0.71-0.98], 0.93 [0.82-0.98] and 0.92 [0.81-0.98] for the diaphragm; 0.96 [0.86-0.99], 0.98 [0.94-0.99] and 0.99 [0.96-1] for the biceps brachii and 0.91 [0.51-0.98], 0.97 [0.93-0.99] and 0. 99 [0.97-1] for the rectus femoris. The probability to reach intra-class correlation coefficient greater than 0.8 in a 10,000 bootstrap sampling for inter-operator reproducibility was respectively 81%, 84% and 78% for the diaphragm, the biceps brachii and the rectus femoris respectively.Conclusions: SWE is a reliable technique to evaluate limb muscles and the diaphragm in both healthy controls and in critically ill patients. Trial registration: The study was registered (ClinicalTrial NCT03550222).

Ultrasound shear wave elastography for assessing diaphragm function in mechanically ventilated patients: a breath-by-breath analysis

“…Recently, Flatres et al performed measurements of shear modulus in the diaphragm (i.e. at the end of expiration only) and in limb muscles of critically ill patients and found a good intra- and inter-operator reliability, but the relationship with diaphragm function was not investigated [ 24 ]. Therefore, the present study aimed at investigating: (i) the agreement between changes in SMdi and changes in transdiaphragmatic pressure in mechanically ventilated patients and (ii), whether or not changes in SMdi are responsive to respiratory load when varying the ventilator settings.…”

Novel High-Quality Sonographic Methods to Diagnose Muscle Wasting in Long-Stay Critically Ill Patients: Shear Wave Elastography, Superb Microvascular Imaging and Contrast-Enhanced Ultrasound

“…Concerning SWE, although there has been an increase in the number of studies regarding musculoskeletal elastography [ 7 ], this technique has barely been studied in the setting of critically ill patients [ 29 ], particularly in those patients with suspected ICUAW and on long-term mechanical ventilation. SWE, as stated earlier, is a method of US imaging based on the detection of shear wave propagation through tissues.…”

Comparison of Shear Wave Elastography and Dynamometer Test in Muscle Tissue Characterization for Potential Medical and Sport Application

“…Moreover, shear modulus is associated with muscle fibrosis after radiotherapy. SWE could be performed easily at the bed side of critically ill population at high risk of muscle edema (46). In the recent years special interest was focused on physical training for cancer patients at the different stage of the malignant disease development.…”