Title : New trends of pressure oscillation in lung therapy
Abstract:
Lung therapies vary between pharmaceutical and physical treatments depending on the nature of the diseases. The latter has gained enormous applications in particular in managing airway constrictions such as during an asthmatic attack. Pressure oscillation (PO) is a form of acoustic/vibration waves superimposed on the breathing cycle and has been used as an innovative and effective way of treating several lung ailments including obstructive sleep apnea (OSA), asthma and respiratory distress syndrome (RDS). Various mechanisms in different parts of the lung can generate breathing difficulties. As an example, the main driving mechanism for the excessive airway narrowing during an asthma attack is the airway smooth muscles (ASM) hyperconstriction caused by the actomyosin cross-bridge cycling process. This process consists of an electrical stimulation triggering chemical activation followed by mechanical attachment/detachment between myosin and actin. This leads to lumen contraction and then respiratory bronchoconstriction. One of the main current pharmaceutical treatments is based on using beta products to target the chemical process and block the calcium channels for muscles relaxation. However, a series of in vitro experiments and in vivo trials have demonstrated that both tidal and superimposed length oscillations disturb the crossbridge cycling process and reduce the active force in contracted ASM (healthy and asthmatics) for a relatively long term. We further investigated the combined effects of bronchodilators and length oscillations on contracted isolated ASM, with the focus on the muscle conditions subsequent to treatment. This work suggests that relaxation subsequent to the application of combined bronchodilator and length oscillations is larger than the added effect of each one when applied alone. This study gives more insight into the role of bronchodilators and oscillations on contracted airways. It demonstrates that PO does trigger lung therapy technologies to improve lung compliance and inflammatory stresses, preserve surfactant function and relax contracted ASM.