Continuous pneumothorax monitoring by remittance measurement

The feasibility of a noninvasive method, based on a remittance measurement, to monitor continuously for the occurrence of pneumothorax in neonates under ventilation, was investigated through animal experiments. Light from a He-Ne laser (632.8 nm) or a semiconductor laser (790 nm) was incident on the chest wall of rabbits and piglets. The remittance was measured as a function of distance from the source. Remittances under physiological conditions were compared with remittances during the introduction of an artificial pneumothorax and with remittances during inflation of the pleural space. The remittance varied with a frequency similar to the respiratory frequency. The amplitude of these variations changed as a function of the volume of air that was introduced into the pleural space (rabbits/He-Ne laser, p < 0.025; piglets/semiconductor laser, p < 0.01). We conclude that optical measurements are potentially usable for monitoring continuously for the occurrence of a pneumothorax in neoatology