Abstract Background: Diaphragmatic weakness is common among patients undergoing mechanical ventilation and is considered a contributing factor in weaning failure. Recent studies have proposed that the ventilator is one of the causes of decreased diaphragm force-generating capacity seen in mechanically ventilated patients. On the other hand, myopathy is a common complication of ICU stay and may delay mechanical ventilation weaning. The study was focused on detecting the changes of both diaphragmatic and quadriceps muscles in different modes of mechanical ventilation by ultrasound and considering diaphragm thickness and excursion as a predictor of weaning outcome. Aim of Study: •Detection of the daily effects of invasive mechanical venti-lation on both diaphragmatic and quadriceps muscles thick-ness by ultrasound •Comparing the effect of controlled versus spontaneous modes of ventilation on diaphragmatic thickness, excursion, and quadriceps muscle thickness by ultrasound. Patients and Methods: This study included 50 invasively mechanically ventilated patients. Diaphragmatic thickness (DT), diaphragmatic excursion (DE), and quadriceps muscle thickness were measured every 48 hours starting from the first day of mechanical ventilation. Results: Patients on spontaneous modes of mechanical ventilation showed higher values of DT (on days 4 and 8) and DTF (on days 2, 6, and 10) compared to patients on controlled modes. Also, patients with successful weaning showed higher values of DTF (on days 0 and 8) and DE (on days 2 and 8) than those with failed weaning. The changes in diaphragmatic functions had occurred as early as the first days of mechanical ventilation. The receiver operator characteristic (ROC) curves showed cut-off points for successful weaning of 0.33 and 19mm for DTF and DE, respectively. Quadriceps muscle showed a daily decrease in thickness regardless of the mode of ventilation, and there was no correlation with either DTF or DE.
Conclusion: There was a continuous decline of DT and DTF among patients on controlled modes of mechanical ventilation compared to spontaneous modes. Also, there was a continuous decline in DTF and DE among patients with failed weaning compared to patients with successful weaning.