A long-period fibre grating monitor of respiratory volumes for the use in non-invasive mechanical ventilation

Abstract

The ventilators involved in mechanical ventilation are usually equipped with pneumatic sensor detecting patient's own respiratory effort in order to assist spontaneous breathing. However, the interface of the mask with the patient promotes air leaks that affect the measurement of pneumatic variables and hence induces patient-ventilator asynchrony. In this paper we describe a new method and apparatus for continuous monitoring of the respiration based on the measurement of chest wall movements. The proposed solution uses a long-period fibre grating sensor attached to patient's thorax and a simple and cost-effective monochromatic measurement scheme. On a set of healthy volunteers, we have established the linear correlation between the change in local torso curvature and the tidal volume during clinically relevant breathing patterns. The chest-wall movement measured by the grating advances with respect to the air-flow signal by about 200 ms, indicating the possibility to lead to more confidence triggering decision. The proposed scheme is non-invasive, simple, low-cost, and immune to air-leaks and drifts that are limiting factors in the currently standard pneumatic measurement techniques.

Assessing the Tidal Volume through Wearables: A Scoping Review

“…Nine of the retained studies tested the feasibility and accuracy of using an optical sensor-based approach to assess the tidal volume ( Table 2 ) [ 12 , 34 , 50 , 52 , 54 , 55 , 56 , 58 , 60 ]. Noticeably, these studies have been carried out by five independent research groups; thus, some of the reported results appeared redundant.…”

“…Two main sensing principles have been proposed among the studies. The first consists of an optical structure inducing a change in the spectral profile of the light traveling along the sensor due to bending (long-period grating sensors [ 34 , 50 , 58 , 60 ]; few-mode fiber Mach–Zehnder interferometer [ 12 ]) or strain (fiber Bragg grating sensors [ 54 , 55 , 56 ]). These sensors are usually embedded (glued or stitched) in fitting garments or suitable elastic bands, and they are designed to monitor changes in the chest and abdomen curvature/circumference while breathing.…”

Real-time chest-wall-motion tracking by a single optical fibre grating: a prospective method for ventilator triggering

“…The signal generated by heart activity superposes on the chest-wall-motion signal and in our measurements it is an unwanted part of the signal (Ivanovic and Petrovic 2016). The wavelet filtering method was applied on the drift-less LPG signals to eliminate the heart signal from the respiratory activity, figure 4.…”

“…The purpose of this study was to investigate the time relationship between these two signals, and hence test the possibility of using chest-wall motion as a confident triggering mechanism. We paid particular attention to elimination of the heartbeat signal shown to be detrimental for accurate detection of the inhalation and exhalation onsets (Ivanovic and Petrovic 2016).…”