Proceedings of Réanimation 2018, the French Intensive Care Society International Congress: physiotherapists’ communications

Abstract

Introduction: Recent research in the areas of the simulation and virtualization have encouraged us, and permits to refine our approach in the framework of chest physiotherapy for newborn infants. The Multidisciplinary Team original as we have incorporated brings together researchers in applied mathematics, physics, biomechanics, mechatronics, fluid mechanics, respiratory physiology and physiotherapists. Here we develop the approach used for the design of the simulator, and the theoretical elements which support. Patients and Methods: This study is based on three separate submodels-one for the lung, one for the thorax and one to mimic chest physiotherapy manipulations. We build a minimal model, which includes only the core properties we identified as playing an important role in chest physiotherapy. This choice was mainly made in order to be able to interpret correctly the interactions between these core phenomena. It was also a way to limit the computation times of the numerical studies. As a consequence, our model can perform qualitative and comparative predictions, but not quantitative predictions. Results: Our results indicate that manipulations need to overcome secretions threshold in order to be able to mobilize secretions. Our model shows that manipulations main effect is to reduce the hydrodynamic resistance of the airway tree by secretions redistribution in the tree, eventually reaching a distribution that is not anymore affected by the manipulation. This effect means that patient breathing might be instantly improved by the manipulation. The second main effect is mucus expectoration, which is also another mean to improve the status of the patient. Mucus expectoration predicted by our model is nonnegligible only for pressures high enough, and also, in the case of high frequency chest wall oscillation (HFCWO), for frequencies high enough. These conclusions, essentially mechanistic, do not depend qualitatively on the initial mucus distribution. Conclusion: This collaboration allows us today to confront our practice to the theory, test our assumptions, in coherence with the scientific data updated. Finally, we proposed two numbers to measure the efficiency of the manipulations-the Shrek number and the comfort number. They are both performing well in the case of our idealized manipulations. They need however to be validated with clinical studies. The first mathematical and digital models from this collaboration are encouraging and offer avenues that we can build on as our works move forward. Co-37 Feasibility and safety of early mobilization in critically ill children