Non-invasive respiratory monitoring using long-period fiber grating sensors

Abstract

In non-invasive ventilation, continuous monitoring of respiratory volumes is essential. Here, we present a method for the measurement of respiratory volumes by a single fiber-grating sensor of bending and provide the proof-of-principle by applying a calibration-test measurement procedure on a set of 18 healthy volunteers. Results establish a linear correlation between a change in lung volume and the corresponding change in a local thorax curvature. They also show good sensor accuracy in measurements of tidal and minute respiratory volumes for different types of breathing. The proposed technique does not rely on the air flow through an oronasal mask or the observation of chest movement by a clinician, which distinguishes it from the current clinical practice.

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

“…1a). As a source, we employ a fiber-coupled narrowband temperature-and current-stabilized DFB laser diode with a central wavelength 1470.73 nm and a tuning range of 5 nm (Petrovic 2014;. The thorax motion is detected using the lateral filtering interrogation technique.…”

“…Most devices constructed for this purpose [respiratory inductance plethysmography (Watson 1980), transthoracic impedance pneumography (Drummond et al 1996), fiber-optic respiratory plethysmography (Davis et al 1997), optoelectronic plethysmography (Aliverti 2000) and plethysmography based on LPG sensors (Allsop 2007)] have been based on the discovery of Konno and Mead who have shown the correlation between the volume of the inhaled air and thoracic and abdominal movements caused by breathing (Konno and Mead 1967). However, each of the proposed devices has a disadvantage that has prevented its use in clinical practice (Petrovic 2014).…”

Fiber-optic sensors for monitoring patient physiological parameters: a review of applicable technologies and relevance to use during magnetic resonance imaging procedures

“…124,125 Preliminary studies of longperiod gratings (LPGs), a variation of Bragg gratings, for recording ventilatory movements and/or volumes have been performed because these gratings are particularly sensitive to any deformations in the LPG section. [126][127][128][129][130][131][132] Change in thorax curvature is sensed as bending of an LPG attached to the thorax. Bending induces strain and stress across the fiber and, in consequence, a change in its refractive index via the strain-optic effect, which manifests as a change in position, shape and amplitude of resonant bands in the transmission spectrum.…”

“…Until recently, complex and expensive transceiving systems were used to handle LPG-based sensors, although the latest studies present a monochromatic measurement scheme that requires only a photodiode as a detector. 132 Moreover, a fiber LPG curvature sensing scheme has been presented lately as a system capable for detecting the mechanical motions and/or sounds of the human heart from surface of the torso. 133 Table 5 lists the major properties of FBG-based sensors for respiration and/or heart function monitoring.…”

Long-period grating fiber-optic sensors of bending for applications in pulmonology

“…Naš metod se zasniva na pretpostavci da su zapremina udahnutog vazduha i promena krivine grudnog koša korelisane [25,26]. Pritom se podrazumeva da se senzor postavlja na čvrsti deo grudnog koša u predelu rebara čime se maksimalno izbegava šum koji potiče od pomeranja mekih tkiva, slika 3.…”