Ultrasound-Assessed Diaphragmatic Dysfunction as a Predictor of Weaning Outcome

"Diaphragm ultrasound will be done while patient is supine on T-piece during SBT 30 minutes after disconnecting mechanical ventilation. The measurements will be done by placing the transducer in the eighth or ninth intercostal space, between the anterior axillary and the mid-axillary lines.~Diaphragmatic excursion (DE) will be measured in M-mode using a 1- to 5- Megahertz (MHz) ultrasound curved transducer during maximal breathing. The amplitude of diaphragmatic excursion will be measured as the point of maximal height of the diaphragm to the base line.~Diaphragmatic thickness (DT) will be measured at both end of maximal inspiration and end of maximal expiration using a high frequency 7-11 MHz ultrasound linear transducer in M-mode. The diaphragm thickness will be measured from the middle of the pleural line to the middle of the peritoneal line."