Shear Wave Elastography, a New Tool for Diaphragmatic Qualitative Assessment A Translational Study

Yassir Aarab (1, 2, 3) , Aurélien Flatres (1, 3) , Fanny Garnier (3, 4) , Mathieu Capdevila (1, 5) , F. Raynaud (1) , Alain Lacampagne (1) , David Chapeau (3) , Kada Klouche (1, 3) , Pascal Etienne (6) , Samir Jaber (2, 1) , Nicolas Molinari (3, 4) , Lucie Gamon (3) , Stefan Matecki (1, 3) , Boris Jung (3, 1)

1 PhyMedExp - Physiologie & médecine expérimentale du Cœur et des Muscles [U 1046]
2 CHRU Montpellier - Hôpital Saint Eloi
3 CHRU Montpellier - Centre Hospitalier Régional Universitaire [Montpellier]
4 IDESP - Institut Desbrest de santé publique
5 Département d'anesthésie-réanimation[Montpellier]
6 L2C - Laboratoire Charles Coulomb

Rationale: Prolonged mechanical ventilation is often associated with either a decrease (known atrophy) or an increase (supposed injury) in diaphragmatic thickness. Shear wave elastography is a noninvasive technique that measures shear modulus, a surrogate of tissue stiffness and mechanical properties.Objectives: To describe changes in shear modulus (SM) during the ICU stay and the relationship with alterations in muscle thickness. To perform a comprehensive ultrasound-based characterization of histological and force production changes occurring in the diaphragm.Methods: Translational study using critically ill patients and mechanically ventilated piglets. Serial ultrasound examination of the diaphragm collecting thickness and SM was performed in both patients and piglets. Transdiaphragmatic pressure and diaphragmatic biopsies were collected in piglets.Measurements and Main Results: We enrolled 102 patients, 88 of whom were invasively mechanically ventilated. At baseline, SM was 14.3 ± 4.3 kPa and diaphragm end-expiratory thickness was 2.0 ± 0.5 mm. Decrease or increase by more than 10% from baseline was reported in 86% of the patients for thickness and in 92% of the patients for SM. An increase in diaphragmatic thickness during the stay was associated with a decrease in SM (β = −9.34 ± 4.41; P = 0.03) after multivariable analysis. In the piglet sample, a decrease in SM over 3 days of mechanical ventilation was associated with loss of force production, slow and fast fiber atrophy, and increased lipid droplets accumulation.Conclusions: Increases in diaphragm thickness during critical illness is associated with decreased tissue stiffness as demonstrated by shear wave ultrasound elastography, consistent with the development of muscle injury and weakness.

Mots clés: Diaphragmatic dysfunction; Diaphragmatic ultrasonography; Mechanical ventilation; Transdiaphragmatic pressure

Domaines: Médecine humaine et pathologie; Pneumologie et système respiratoire

Yassir Aarab, Aurélien Flatres, Fanny Garnier, Mathieu Capdevila, F. Raynaud, et al.. Shear Wave Elastography, a New Tool for Diaphragmatic Qualitative Assessment A Translational Study. American Journal of Respiratory and Critical Care Medicine, 2021, 204 (7), pp.797-806. ⟨10.1164/rccm.202011-4086OC⟩. ⟨hal-03286291⟩