Resources / Publications

Scientific Publication Citing Dragonfly

Measurement of regional pleural deformation during mechanical ventilation by ultrasonic elastography: A proof of concept study

Martin Girard (1)
Girard's Doctoral Thesis, August 2020.

---

Keywords

Anesthesia, General; Humans; Lung/diagnostic imaging/physiopathology; Positive-Pressure Respiration/adverse effects; Ultrasonography/methods; Ventilator-Induced Lung Injury/diagnostic imaging/physiopathology

---

Abstract

Mechanical ventilation is a common therapy in operating rooms and intensive care units. When ill-adapted, it can lead to ventilator-induced lung injury (VILI), which in turn is associated with poor outcomes. Excessive regional pulmonary strain is thought to be a major mechanism responsible for VILI. Scarce bedside methods exist to measure regional pulmonary strain. We propose a novel way to measure regional pleural strain using ultrasound elastography. We conducted a single blind randomized crossover pilot study in 10 patients requiring general anesthesia. After induction, patients were received tidal volumes of 6, 8, 10 and 12 mL.kg-1 in random order, while pleural ultrasound cineloops were acquired at 4 standardized locations. Ultrasound radiofrequency speckle tracking allowed computing various pleural translation, strain and shear components. These were screened to identify those with the best dose-response with tidal volumes using linear mixed effect models. Goodness-of-fit was assessed by the coefficient of determination. Intraobserver, interobserver and test-retest reliability were calculated using intraclass correlation coefficients. Analysis was possible in 90.7% of ultrasound cineloops. Lateral absolute shear, lateral absolute strain and Von Mises strain varied significantly with tidal volume and offered the best dose-responses and data modelling fits. Point estimates for intraobserver reliability measures were excellent for all 3 parameters (0.94, 0.94 and 0.93, respectively). Point estimates for interobserver (0.84, 0.83 and 0.77, respectively) and test-retest (0.85, 0.82 and 0.76, respectively) reliability measures were good. Thus, strain imaging is feasible and reproducible, and may eventually guide mechanical ventilation strategies in larger cohorts of patients.

---

How Our Software Was Used

Dragonfly was used to compute elastography images and mechanical parameters within the ROI over consecutive frames.

---

Author Affiliation

(1) Department of Anaesthesiology, Centre hospitalier de l’Université de Montréal, 1000 rue St-Denis, Montréal, Qc, Canada, H2X 3J4.

---

Return to Publications list.