Pneumothorax monitoring by remittance measurement: Comparison between experimental model and animal studies

Pneumothorax monitoring by remittance measurement in neonatology is investi gated using model experiments. The results are compared to previous animal experiments. A multifibre probe is used to measure the change in remittance at 632.8 nm and 790 nm as a function of the thickness of a layer of air be tween a model chest wall (optically matched to piglet chest walls) and a mo del lung. An increase in thickness of this layer of air results in a decrea se in remittance. Only when a relatively thin model chest wall is used (thi ckness 4 or 6 mm) and detection fibres are at some distance from the source , is this decrease in remittance preceded by an initial increase in remitta nce. Relative changes in remittance are larger at 790 nm then at 632.8 nm. The results in general correspond to the results of the animal experiments. However, not all results of the animal experiments could be explained. We conclude that our assumptions for the model experiments did not cover all a spects of the development of a pneumothorax and dynamic models with changin g optical properties should be used instead. In conclusion, the results in general confirm and help understand the results of the animal experiments a nd indicate that pneumothorax monitoring by remittance measurement is feasi ble.