Anatomical models to study aerosol delivery impose huge limitations and extrapolation to humans remains controversial. This study aimed to develop and validate an ex vivo human-like respiratory tract model easy to use and relevant to compare to in vivo human data. A human plastinated head is connected to an ex vivo porcine pulmonary tract ventilated artificially by passive expansion. A physiological study measures “pleural” depressions, tidal volumes, and minute ventilation for the respiratory rates chosen (10, 15, and 20 per minute) with three inspiratory/expiratory ratios (1/1, 1/2, and 1/3). Scintigraphy with 81mKrypton assesses the homogeneity of the ventilation. Forty different experiments were set for validation, with 36 (90%) ventilating successfully. At a respiratory rate of 15/minute with inspiratory/expiratory ratio of 1/2, the tidal volume average was 824 mL (standard deviation, 207 mL). The scintigraphy performed on 16 ex vivo models (44.4%), showed homogenous ventilation with great similarity to human physiological studies. Ratio of the peripheral to central count rates were equally correlated with human data published in the literature. This new model, combining research feasibility and human physiology likeness, provides a realistic approach to human inhalation and therefore can be an interesting tool in aerosol regional deposition studies.

To relate exposure to adverse health effects, it is necessary to know where particles in the submicron range deposit in the respiratory tract. The possibly higher vulnerability of children requires specific inhalation studies. However, radio-aerosol deposition experiments involving children are rare because of ethical restrictions related to radiation exposure. Thus, an in vivo study was conducted using three baboons as a child respiratory tract model to assess regional deposition patterns (thoracic region vs. extrathoracic region) of radioactive polydisperse aerosols ([d16–d84], equal to [0.15 µm–0.5 µm], [0.25 µm–1 µm], or [1 µm–9 µm]). Results clearly demonstrated that aerosol deposition within the thoracic region and the extrathoraic region varied substantially according to particle size. High deposition in the extrathoracic region was observed for the [1 µm–9 µm] aerosol (72%±17%). The [0.15 µm–0.5 µm] aerosol was associated almost exclusively with thoracic region deposition (84%±4%). Airborne particles in the range of [0.25 µm–1 µm] showed an intermediate deposition pattern, with 49%±8% in the extrathoracic region and 51%±8% in the thoracic region. Finally, comparison of baboon and human inhalation experiments for the [1 µm–9 µm] aerosol showed similar regional deposition, leading to the conclusion that regional deposition is species-independent for this airborne particle sizes.

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We present a rare case of a chylothorax in a 60-year-old patient after resection of the thymus (myasthenia gravis and thymus hyperplasia). A left-sided chylothorax developed 20 days after the resection with an estimated daily fluid loss of 1.7 l.Chest lymphoscintigraphy was performed in the anterior and posterior position 60 min after injection of 4×74 MBq 99m Tc filtered sulphur colloid subcutaneously into the first interdigital space and the retromalleolar space of both feet. The images showed abnormal tracer accumulation in the left hemithorax, as seen on the posterior chest lymphoscintigraphic image. SPECT/CT (Symbia T2 Siemens Medical) of the thorax showed abnormal mediastinal tracer accumulation between the left common carotid artery and the left subclavian artery, suggesting rupture of a collateral thoracic lymph duct. Successful ligation of a ruptured ectopic thoracic duct, situated ventral to the left subclavian artery and the phrenic nerve, by video-assisted thoracoscopic surgery was performed and achieved control of the chylothorax.This case clearly illustrates the added value of SPECT/ CT in addition to lymphoscintigraphy for the anatomical location of a traumatic rupture of a thoracic lymph duct. To our knowledge only a few case reports have been published on this subject [1][2][3][4].

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