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

Pneumothorax monitoring by remittance measurement in neonatology is investigated 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 between a model chest wall (optically matched to piglet chest walls) and a model lung. An increase in thickness of this layer of air results in a decrease in remittance. Only when a relatively thin model chest wall is used (thickness 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 remittance. 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 aspects of the development of a pneumothorax and dynamic models with changing optical properties should be used instead. In conclusion, the results in general confirm and help understand the results of the animal experiments and indicate that pneumothorax monitoring by remittance measurement is feasible.