ABS-MV

Abdominal Muscle Thickness in Mechanically Ventilated Patients During Spontaneous Breathing Trial

Study Investigators

Dr. Ewan Goligher (ext. 6810, ewan.goligher@uhn.ca)

Dr. Annia Schreiber (anniafleur.schreiber@gmail.com)

Study Contact

Jenna Wong (ext. 7613, jenna.wong@uhn.ca)

Samira Fard (samira.fard@uhn.ca)

Study Summary

A prospective observational study aiming to characterize the effect of positive end-expiratory pressure (PEEP) on ventilator-induced lung injury in patients with ARDS and to analyze different techniques for determining optimal PEEP to avoid such injury.

Study Population

Patients greater than 18 years of age, requiring mechanical ventilation and meet the readiness to wean criteria as per clinical protocol. 

Study Objectives

1. To quantify the activity of the abdominal muscles during a spontaneous breathing trail (SBT).

2. To assess the validity of measuring maximal abdominal muscle thickening and abdominal muscle thickening during coughing to estimate abdominal muscle function.

3. To determine the reproducibility of measurements of abdominal muscle thickness and thickening fraction in mechanically ventilated patients.

4. To assess the validity of an ultrasonographic tension time index of the diaphragm (US-TTidi), derived from the mean and maximal fractional thickening of the diaphragm, to estimate the occurrence of diaphragm fatigue during SBT.

5. To assess the relationship between abdominal muscle thickening and the outcomes of SBT and extubation.

6. To assess the relationship between the US-TTdi and the outcomes of SBT and extubation.

7. To describe the changes in tissue oxygenation of the brain, respiratory muscles and skeletal muscles during SBT.

Study Interventions

Prior to the SBT, baseline diaphragm and abdominal muscle ultrasound measurements will be obtained. During the SBT, maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP), and diaphragm and abdominal muscle ultrasound will be measured.

Why it Matters

Non-invasive techniques for evaluating abdominal muscle function and structure would be of great value, given the importance of abdominal muscle function in compensating for excess respiratory mechanical loads. Such measurements may help assess the contribution of poor abdominal muscle function to weaning dysfunction and provide a means of monitoring changes in abdominal muscle thickness over time.