Diaphragm ultrasound as a new functional and morphological index of outcome, prognosis and discontinuation from mechanical ventilation in critically ill patients and evaluating the possible protective indices against VIDD

Abstract

Background: There is increasing awareness that diaphragm weakness is common in patients undergoing MV and is likely a contributing cause of weaning failure. Recent studies have suggested that the ventilator is a likely cause of the decreased diaphragm force generating capacity (dFGC) seen in mechanically ventilated patients; a condition referred to as ventilator-induced diaphragmatic dysfunction (VIDD). The study was focused on using diaphragm thickness and excursion measured by ultrasound as a predictor of weaning outcome and to assess the clinical evolution and risk factors for VIDD in an adult intensive care unit (ICU) and evaluating the possible protective indices against VIDD. Patients and methods: This study included 60 invasively mechanically ventilated patients matched with twenty healthy non-mechanically ventilated individuals as a control group. Diaphragm thickness and excursion measured daily for 14 days or until extubation or death. Results: Here was a significant decrease in the MDT, DTF and mean diaphragmatic excursion with increased length and duration of mechanical ventilation. the maximum diaphragmatic changes occurred early in the first 3 days after MV. Cutoff values for diaphragmatic ultrasound predicting successful weaning were MDT >2 mm, DTF >30% and DE >1.5 cm. Early switch from controlled MV to assist ventilation (addition of PS and or PEEP) was associated with reversal of VIDD. Conclusion: Ultrasound is a sensitive accurate method for predicting weaning outcome. Maintaining mechanically ventilated at a controlled mild to moderate hypercapnia, early switch from controlled MV to PS and or addition of PEEP improve weaning outcome.

Keywords

• Diaphragm thickness
• Diaphragmatic excursion
• Weaning
• Mechanical ventilation
• Ultrasound