Optical mapping of the thoracoabdominal wall.

Abstract

An optical technique has been developed for mapping the size and shape of the thoracoabdominal wall and the change in its shape with breathing. A fixed pattern composed of stripes of light is projected on to both sides of the trunk. These stripes become distorted when viewed from in front and behind, forming contours over the trunk surface. The contours are photographed and then encoded digitally. The digital information can be used to compute automatically the volume of the trunk, the position of any point on its surface, and its cross sectional shape at any level. The technique has been tested on rigid objects (a globe, a cone, and two dummy torsos) that can be measured precisely. With this optical technique linear dimensions can be calculated to within 0O5 mm, cross sectional area to within 5%, and volume to within 16-3-7%. These results suggest that this non-invasive technique measures the shape and volume of complex three dimensional surfaces with sufficient accuracy to be tried in clinical practice.In a previous paper we outlined the principles underlying one optical method of determining the size, shape, and movement of the thoracoabdominal wall.' In essence, stripes of light are projected on to both sides of the body and viewed from in front and behind. The illuminated contours of the trunk become obvious at these angles and can be computed automatically. This method is derived from those developed for the face by Lovesey2 and Cobb3 and for the trunk by Kovats4 5 and has some similarities to methods described more recently by Whittle et a16 and Saumarez7 but, unlike their techniques, it looks at both sides of the trunk simultaneously and lends itself more readily to clinical practice. This paper presents the formal verification of the technique. Method APPARATUS AND PROCEDUREIn principle, the patient or the test object is placed in a box of informative light that can be viewed from opposing angles. The patient stands on a platform in a steel reference frame (fig 1) that identifies where the box of light is. The height of the platform is adjusted so that the trunk is illuminated from the larynx to the symphysis pubis. Provided that patients' underclothes are close fitting, they do not

Efetividade de um modelo fotogramétrico para a análise da mecânica respiratória toracoabdominal na avaliação de manobras de isovolume em crianças

“…(15) The thoracoabdominal contour and movement can be determined using various surface methods, according to various physical principles, such as magnetometry, (18) inductive plethysmography, (19) kinetic imaging (20) and light projection. (21) Twoor three-dimensional information obtained with any of these methods is used to infer clinically relevant aspects of the respiratory mechanics.…”

Quelles pistes pour la recherche des 10 prochaines années en matière de désencombrement ?

“…Cette technique a été validée [21] et déjà utilisée abondamment en réanimation pour objectiver les effets de la ventilation notamment ; l'index de clairance mucociliaire : cette technique, validée et reproductible [22], a été utilisée dans le contexte la dyskinésie ciliaire primitive ou des bronchiectasies mais surtout de la mucoviscidose notamment pour objectiver l'effet des traitements et les changements au niveau pulmonaire vu sa meilleure sensibilité que la spirométrie, principalement au niveau des petites voies aérien-nes [23]. Il est possible d'imaginer que cet index puisse mesurer de manière plus adéquate que le VEMS l'impact à court terme de la kinésithérapie sur la fonction pulmonaire ; la pléthysmographie par la lumière structurée : c'est une méthode non invasive qui utilise une lumière structurée pour mesurer la fonction pulmonaire et dévelop-pée il y a plus de 30 ans [24]. Cette technique utilise la distorsion de la lumière liée au mouvement pour calculer le volume ou le changement de volume.…”

A 3D machine vision method for non-invasive assessment of respiratory function

“…If images are captured continuously then changes in the illumination pattern can be used to calculate body shape changes and hence breathing volumes. Early research employing triangulation of light stripes indicated that good accuracy could be obtained , but at the time the technique was not developed into systems that could be used on the ward, presumably due to the expense and performance limitations associated with the imaging and computing technology available. Today, high‐resolution digital cameras and high‐performance computing hardware are both relatively low cost, so that optical systems for real‐time breathing monitoring are becoming a viable commercial possibility.…”