Airborne ultrasound measurement of posturo-respiratory interaction

Abstract

In healthy subjects, spinal alignment varies with the variations of lung volume and the natural breathing perturbs physiologically the balance. The reciprocal action between respiratory postural perturbation and partial counteraction of cyclic movements of the spine, pelvis and lower limbs represents the posturo-respiratory interaction (PRI). The PRI is centrally controlled. In the Obstructive Sleep Apnoea Syndrome (OSAS) specifics postural dysfunctions related to an abnormal PRI is observed. Numerous tools exist to measure the PRI. We propose an alternative approach which is contactless and non-invasive using airborne ultrasound devices. This approach offers the advantages to simultaneously assess breathing and postural variations and to be easily implemented in clinical settings. We first evaluate the performance of our device to assess the breathing pattern compared to that of a spirometer. We secondly use our approach to qualify the PRI by measuring the postural variation at the level of the T7 vertebra. We introduce a new parameter named pseudo-emergence similar to the classical emergence parameter. This parameter gives a value of 8.33%. This value is close to the median emergence that was compute from predecessor. We have demonstrated that the proposed method allows a reliable measurement of breathing. We also offer a contactless approach of a respiratory pseudo-emergence parameter to evaluate the PRI. The obtained parameters seem promising and consistent with the literature, but need to be confirm.