Despite advances in respiratory care, the treatment of critical neonatal patients with conventional mechanical ventilation (CMV) techniques has still many drawbacks. To address this issue, Total Liquid Ventilation (TLV) with liquid perfluorocarbons (PFC) has been investigated as an alternative respiratory modality [1,2]. A dedicated TLV ventilator supplies PFC tidal volumes (TV) through an endotracheal tube (ETT) inserted into the trachea. In experimental studies, TLV proved to be able to support pulmonary gas exchange while preserving lung structure and function. Moreover, PFC properties make these liquids an optimal medium to treat neonatal respiratory failure [1–3]. However, different aspects of TLV have to be further investigated for a safe transition from the laboratory experience to the clinical application. One of these aspects is the possible airway and lung injury that may be caused by the peculiar fluid dynamics developed when using an incompressible and viscous liquid instead of air as a respiratory medium. To overcome this issue, continuous reliable real-time monitoring of airway pressure during TLV is crucial. Thus, the instrumentation of the ETT with a pressure transducer (PT) is mandatory to perform a safe TLV treatment [4–6]. At present, no commercial instrumented ETTs designed for TLV are available; thus during TLV experimental animal trials [4–6] ETT prototypes instrumented with homemade PT-equipped catheters are currently used. However, the positioning of this catheter has to be optimized in order to reduce fluid dynamic disturbances that can alter pressure measurements. Aim of this study is to investigate on the PFC fluid-dynamic patterns in the presence of the catheter by computational fluid dynamic (CFD) analysis, in the view of the development of a TLV dedicated instrumented ETT. In particular, the effect of two different positioning of the PT catheter on the PFC fluid dynamics and airway pressure measurement was evaluated for a neonatal ETT.

Severe stenotic or insufficient native heart valves (nHV) must be substituted with artificial heart valve prostheses (aHV) to prevent heart failure. Nowadays, surgeons can implant two types of aHVs: mechanical aHV or bioprosthetic aHV. Mechanical aHVs, which are built up from synthetic hard materials, assure good reliability but require daily anticoagulant treatment to avoid blood cells damage. On the contrary, bioprosthetic aHVs, which are made from animal or human tissues, display better hemocompatibility but significant risk of failure due to tissue degradation. Despite current development in manufacturing of valve prostheses, long-term clinical applications claim for new generation of aHVs able to meet reliability and effectiveness requirements [2].

Marine mammals belonging to the Order of CetoArtiodactyla have developed their organs and adapted their anatomic structures to survive and better exploit the resources of the surrounding water environment. Though belonging to the Mammal Class and, hence, having a cardio-respiratory system based on the gas exchange with the atmosphere, they are able to perform long-lasting immersions and reach considerable depths during diving [1]. On the other hand, the anatomy of the tracheo-bronchial structures of the Family Delfinidae differs from that of terrestrial mammals in the lack of muscular tissue in the posterior region and the irregular shape of the cartilaginous rings (Fig.1a-b-c) [1, 2]. So far, the behavior of dolphin respiratory system during diving is not yet fully understood, since they cannot be subjected to invasive analysis being endangered and protected species. Namely, it remains to ascertain whether the tracheo-bronchial tree collapses during diving or is kept open by the peculiar material properties, the anatomical structure and the presence of entrapped air. Aim of this work is to model the dolphin Tursiops truncatus ’s tracheo-bronchial tree to study its behavior during diving by coupling experimental in vitro mechanical characterization of airways tissues to finite element computational analyses. Furthermore, we performed a comparison between the mechanical behavior of tracheo-bronchial trees of dolphins and that of the goat, a terrestrial mammal whose conformation of the upper airways is similar to the human, to highlight discrepancies due to the different habitats.