Chest wall and lung volume estimation by optical reflectance motion analysis

Abstract

Estimation of chest wall motion by surface measurements only allows one-dimensional measurements of the chest wall. We have assessed on optical reflectance system (OR), which tracks reflective markers in three dimensions (3-D) for respiratory use. We used 86 (6-mm-diameter) hemispherical reflective markers arranged circumferentially on the chest wall in seven rows between the sternal notch and the anterior superior iliac crest in two normal standing subjects. We calculated the volume of the entire chest wall and compared inspired and expired volumes with volumes obtained by spirometry. Marker positions were recorded by four TV cameras; two were 4 m in front of and two were 4 m behind the subject. The TV signals were sampled at 100 Hz and combined with grid calibration parameters on a personal computer to obtain the 3-D coordinates of the markers. Chest wall surfaces were reconstructed by triangulation through the point data, and chest wall volume was calculated. During tidal breathing and vital capacity maneuvers and during CO2-stimulated hyperpnea, there was a very close correlation of the lung volumes (VL) estimated by spirometry [VL(SP)] and OR [VL(OR)]. Regression equations of VL(OR) (y) vs. VL(SP) (x, BTPS in liters) for the two subjects were given by y = 1.01x-0.01 (r = 0.996) and y = 0.96x + 0.03 (r = 0.997), and by y = 1.04x + 0.25 (r = 0.97) and y = 0.98x + 0.14 (r = 0.95) for the two maneuvers, respectively. We conclude spirometric volumes can be estimated very accurately and directly from chest wall surface markers, and we speculate that OR may be usefully applied to calculations of chest wall shape, regional volumes, and motion analysis.

Comparison of different levels of positive expiratory pressure on chest wall volumes in healthy children and patients with fibrosis

“…All individuals were positioned in seated position on a backless bench and centralized in a system of six cameras previously calibrated according to the manufacturer's recommendations and previously published studies [24][25][26] . Subjects were requested to remain motionless breathing freely for 180 seconds.…”

Breathing Movements of the Chest and Abdominal Wall in Healthy Subjects

“…[5][6][7][8][9] These methods are used to estimate lung volumes from the chest and abdominal motions. The respiratory movement measuring instrument, 10 -14 which consists of 6 laser distance sensors, has been developed to measure changes in breathing movements of the thorax and abdomen.…”

Exercise and dyspnoea in COPD

“…Absolute volumes are difficult to estimate for practical reasons but the change in volume can be accurately recorded and broken down into regions of interest, particularly the movement of the pulmonary and abdominal ribcage and the abdominal compartmental volume, which reflects the action of the diaphragm and the abdominal muscles. In healthy subjects, this method gives excellent agreement with lung volume measurements derived from recordings at the mouth made at rest and during exercise [37,38]. When healthy subjects exercised to their maximum performance breathing through a Starling resistor circuit, most of them maintained a relatively constant end-expiratory chest wall volume, although some tried to behave as they normally would and reduced EELV, which was an energetically counterproductive strategy [39].…”