抄録
In recent years, fetal endoscopic tracheal occlusion （FETO） using a balloon has been clinically employed for promoting prenatal lung growth to ameliorate postnatal respiratory failure caused by severe in utero lung hypoplasia. After a successful FETO, in some limited fetal centers, planned or emergency balloon removal using another fetoscopy is performed to release the tracheal occlusion immediately before delivery. To overcome this additional fetoscopy, we previously reported an innovative simple procedure to remove the occluding balloon by bursting it with a pre-planned sequence of high intensity focused ultrasound （HIFU） irradiation. In that previous study, which used rabbits euthanized and submerged in degassed water, we inflated the balloon by injecting a mixture of perfluorocarbon and ultrasound contrast medium through a fetoscopically-guided catheter. The rate of successful balloon burst and deflation using HIFU irradiation was high enough （100％）, but the mode and timing of tracheal reopening （i.e., sudden burst or slow shrinkage of the balloon） was rather varied and collateral damage to the dermal/tracheal tissue was identified in 72.7％ of the experimental animals. Accordingly, to standardize the HIFU irradiation sequence and to achieve a reliable and secure balloon burst, we conducted another series of animal experiments in which the mixture of perfluorocarbon was replaced with “limonene emulsion” （D-limonene micelle emulsified in physiological saline） as the balloon injection fluid. In all 6 animals, we succeeded in reopening the airway by achieving an instantaneous and timely balloon burst without definite skin/tracheal damage. We conclude that HIFU irradiation together with injecting the balloon with “limonene emulsion” is an improved method for safe tracheal release from a balloon occlusion.
