Role of ultrasound assessment of parasternal intercostal muscle thickness during weaning from mechanical ventilation

BackgroundA spontaneous breathing trial (SBT) is a major diagnostic tool to predict successful extubation in patients. Several factors may lead to weaning failure, including respiratory muscle dysfunction. In cases with diaphragmatic dysfunction, there is recruitment of the extradiaphragmatic muscles, including parasternal intercostal muscles.ObjectivesTo study the role of ultrasound assessment of parasternal intercostal muscle thickness during weaning from mechanical ventilation.Patients and methodsThis was a prospective observational study carried out on 40 mechanically ventilated patients, who were clinically stable to undergo a SBT. Parasternal intercostal muscle ultrasound was performed before the start of the SBT. Parasternal intercostal muscle thickness was measured at the end of inspiration (Tic-max) and at the end of expiration (Tdi-min), and then parasternal intercostal muscle thickness fraction (TFic%) was calculated.ResultsThe parasternal intercostal muscle thickness fraction (TFic%) was significantly higher in patients who passed the SBT successfully (23.45 ± 7.04 vs. 7.38 ± 4.33%, P < 0.001). With a cut off value of more than 11.58%, the parasternal intercostal thickness fraction (TFic%) achieved 86.96% sensitivity and 100% specificity (area under the curve = 0.980; P < 0.001).ConclusionUltrasonographic evaluation of the parasternal intercostal muscles using the thickness indices could be a good predictor of SBT outcome.