Diaphragm UltraSound with innovative tecniques and parameters: valuable predictors of the outcome of extubation from mechanical ventilation. An observational pilot study on patients affected by Covid-19 related ARDS

Introduction: Because both early and delayed weaning are associated with increased mortality, longer stay in the ICU and higher economic costs, determining the optimal moment of extubation is necessary. However, weaning failure is extremely common: about 20% of mechanically ventilated patients confront weaning failure and require reintubation. Ultrasound Sonography (US) is an available bedside tool that allows rapid assessment and visualization of the different structures involved in spontaneous breath. M-mode ultrasonography can be useful for the assessment of diaphragm kinetics, providing valuable information about diaphragm disfunction. Aim of the study: The aim of this study is to find a correlation between the value of the acceleration of the diaphragm detected with the US M-mode and the outcome of the weaning. Secondly, we want to assess if this value could be predictive of success or failure in weaning. Materials and methods: We have enrolled 19 patients admitted in our ICU between March 2020 and April 2021. Each patient underwent the trial with the ultrasound M-mode to assess the acceleration of the diaphragm during the contraction: once we have measured the time and the speed from the graph obtained by US M-mode, we have calculated the value of the acceleration for each patient. Then, we have analyzed the results relating them to the outcome of the weaning. Results: While 11 of our patients have had a successful weaning, 8 have failed it. This result does not seem to correlate neither with the sex and the age of the patients, nor with the time of intubation, the time of ICU stay or the duration of positivity for SARS-CoV2. Instead, we can see that both positive and negative outcomes are associated to different values of acceleration Discussion: our study has demonstrated that an assessment of the diaphragm using US could well represent a usable and effective technique. US is an available bedside technique, cost effective and even though operator-dependent, repeatable, as we have focused on the detection of objective and measurable parameters. To sum up, we can demonstrate that the acceleration is related both to the force generated by the diaphragm contraction, and to the transdiaphragmatic pressure, a reliable measure rarely employed to decide the timing of weaning. Our technique could be therefore related to the measure of transdiaphragmatic pressure, but with the advantage of being non-invasive. Conclusions: In conclusion, the acceleration could well be a useful parameter to consider regarding the prediction of success or failure in weaning.