A B S T R A C T In an effort to determine how far inspired air could penetrate into the respiratory tract before being brought to body conditions, we measured the temperature in the airways of the anterior basilar segment of the right lower lobe in five normal subjects while they breathed air at subfreezing and ambient conditions. During quiet breathing, most of the heating of the incoming gas took place in the upper airways as expected. However, as the thermal burden was increased by rapid inspirations, frigid air, and hyperventilation, the temperature of the distal airways progressively fell and the point at which the incoming air reached body conditions moved deep into the periphery of the lung. These findings demonstrate that heat and water transfer is not localized to one region, but rather is a continuous process that begins the moment the air enters the body and involves as much of the respiratory tract as necessary to complete the task.
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
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