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Danan C, Tauzin M, Jung C, Carbonnier B, Dassieu G, Decobert F, Caeymaex L. Instrumental dead space: A glass ceiling for extremely low birth weight preterm infants? A dead space washout bench study. Pediatr Pulmonol 2023; 58:1514-1519. [PMID: 36785523 DOI: 10.1002/ppul.26353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 01/22/2023] [Accepted: 02/09/2023] [Indexed: 02/15/2023]
Abstract
BACKGROUND When ventilating extremely low birth weight infants, clinicians face the problem of instrumental dead space, which is often larger than tidal volume. Hence, aggressive ventilation is necessary to achieve CO2 removal. Continuous tracheal gas insufflation can wash out CO2 from dead space and might also have an impact on O2 and water vapor transport. The objective of this bench study is to test the impact of instrumental dead space on the transport of CO2 , O2 , and water vapor and the ability of continuous tracheal gas insufflation to remedy this problem during small tidal volume ventilation. METHODS A test-lung located in an incubator at 37°C was ventilated with pressure levels needed to reach different tidal volumes from 1.5 to 5 mL. End-tidal CO2 at the test-lung exit, O2 concentration, and relative humidity in the test-lung were measured for each tidal volume with and without a 0.2 L/min continuous tracheal gas insufflation flow. RESULTS CO2 clearance was improved by continuous tracheal gas insufflation allowing a 28%-44% of tidal volume reduction. With continuous tracheal gas insufflation, time to reach desired O2 concentration was reduced from 20% to 80% and relative humidity was restored. These results are inversely related to tidal volume and are particularly critical below 3 mL. CONCLUSION For the smallest tidal volumes, reduction of instrumental dead space seems mandatory for CO2 , O2 , and water vapor transfer. Continuous tracheal gas insufflation improved CO2 clearance, time to reach desired O2 concentration and humidification of airways and, thus, may be an option to protect lung development.
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Affiliation(s)
- Claude Danan
- Neonatal Intensive Care Unit, CHI Créteil, Créteil, France.,INSERM CNRS ERL 7000, IMRB, Université Paris Est Creteil, Créteil, France
| | - Manon Tauzin
- Neonatal Intensive Care Unit, CHI Créteil, Créteil, France
| | - Camille Jung
- Clinical Research Centre, Centre Hospitalier Intercommunal de Créteil, Créteil, France.,Pediatrics, Centre Hospitalier Intercommunal de Creteil, Créteil, France
| | | | - Gilles Dassieu
- Neonatal Intensive Care Unit, CHI Créteil, Créteil, France.,INSERM CNRS ERL 7000, IMRB, Université Paris Est Creteil, Créteil, France
| | - Fabrice Decobert
- Neonatal Intensive Care Unit, CHI Créteil, Créteil, France.,INSERM CNRS ERL 7000, IMRB, Université Paris Est Creteil, Créteil, France
| | - Laurence Caeymaex
- Neonatal Intensive Care Unit, CHI Créteil, Créteil, France.,Faculté de Santé, University Paris Est Creteil, Créteil, Val de Marne, France
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Grebenkov DS, Skvortsov AT. Diffusion toward a nanoforest of absorbing pillars. J Chem Phys 2022; 157:244102. [PMID: 36586989 DOI: 10.1063/5.0132197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Spiky coatings (also known as nanoforests or Fakir-like surfaces) have found many applications in chemical physics, material sciences, and biotechnology, such as superhydrophobic materials, filtration and sensing systems, and selective protein separation, to name but a few. In this paper, we provide a systematic study of steady-state diffusion toward a periodic array of absorbing cylindrical pillars protruding from a flat base. We approximate a periodic cell of this system by a circular tube containing a single pillar, derive an exact solution of the underlying Laplace equation, and deduce a simple yet exact representation for the total flux of particles onto the pillar. The dependence of this flux on the geometric parameters of the model is thoroughly analyzed. In particular, we investigate several asymptotic regimes, such as a thin pillar limit, a disk-like pillar, and an infinitely long pillar. Our study sheds light onto the trapping efficiency of spiky coatings and reveals the roles of pillar anisotropy and diffusional screening.
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Affiliation(s)
- Denis S Grebenkov
- Laboratoire de Physique de la Matière Condensée, CNRS-Ecole Polytechnique, Institut Polytechnique de Paris Paris, 91120 Palaiseau, France
| | - Alexei T Skvortsov
- Maritime Division, Defence Science and Technology Group, 506 Lorimer Street, Fishermans Bend, Port Melbourne, Victoria 3207, Australia
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Schmid K, Knote A, Mück A, Pfeiffer K, von Mammen S, Fischer SC. Interactive, Visual Simulation of a Spatio-Temporal Model of Gas Exchange in the Human Alveolus. FRONTIERS IN BIOINFORMATICS 2022; 1:774300. [DOI: 10.3389/fbinf.2021.774300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 12/17/2021] [Indexed: 11/13/2022] Open
Abstract
In interdisciplinary fields such as systems biology, good communication between experimentalists and theorists is crucial for the success of a project. Theoretical modeling in physiology usually describes complex systems with many interdependencies. On one hand, these models have to be grounded on experimental data. On the other hand, experimenters must be able to understand the interdependent complexities of the theoretical model in order to interpret the model’s results in the physiological context. We promote interactive, visual simulations as an engaging way to present theoretical models in physiology and to make complex processes tangible. Based on a requirements analysis, we developed a new model for gas exchange in the human alveolus in combination with an interactive simulation software named Alvin. Alvin exceeds the current standard with its spatio-temporal resolution and a combination of visual and quantitative feedback. In Alvin, the course of the simulation can be traced in a three-dimensional rendering of an alveolus and dynamic plots. The user can interact by configuring essential model parameters. Alvin allows to run and compare multiple simulation instances simultaneously. We exemplified the use of Alvin for research by identifying unknown dependencies in published experimental data. Employing a detailed questionnaire, we showed the benefits of Alvin for education. We postulate that interactive, visual simulation of theoretical models, as we have implemented with Alvin on respiratory processes in the alveolus, can be of great help for communication between specialists and thereby advancing research.
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Blanquez-Nadal M, Piliero N, Guillien A, Doutreleau S, Salvat M, Thony F, Pison C, Augier C, Bouvaist H, Aguilaniu B, Degano B. Exercise hyperventilation and pulmonary gas exchange in chronic thromboembolic pulmonary hypertension: Effects of balloon pulmonary angioplasty. J Heart Lung Transplant 2021; 41:70-79. [PMID: 34742646 DOI: 10.1016/j.healun.2021.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 08/25/2021] [Accepted: 09/14/2021] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Excessive ventilation (V̇E) and abnormal gas exchange during exercise are features of chronic thromboembolic pulmonary hypertension (CTEPH). In selected CTEPH patients, balloon pulmonary angioplasty (BPA) improves symptoms and exercise capacity. How BPA affects exercise hyperventilation and gas exchange is poorly understood. METHODS In this longitudinal observational study, symptom-limited cardiopulmonary exercise tests and carbon monoxide lung diffusion (DLCO) were performed before and after BPA (interval, mean (SD): 3.1 (2.4) months) in 36 CTEPH patients without significant cardiac and/or pulmonary comorbidities. RESULTS Peak work rate improved by 20% after BPA whilst V̇E at peak did not change despite improved ventilatory efficiency (lower V̇E with respect to CO2 output [V̇CO2]). At the highest identical work rate pre- and post-BPA (75 (30) watts), V̇E and alveolar-arterial oxygen gradient (P(Ai-a)O2) decreased by 17% and 19% after BPA, respectively. The physiological dead space fraction of tidal volume (VD/VT), calculated from measurements of arterial and mixed expired CO2, decreased by 20%. In the meantime, DLCO did not change. The best correlates of P(Ai-a)O2 measured at peak exercise were physiological VD/VT before BPA and DLCO after BPA. CONCLUSIONS Ventilatory efficiency, physiological VD/VT, and pulmonary gas exchange improved after BPA. The fact that DLCO did not change suggests that the pulmonary capillary blood volume and probably the true alveolar dead space were unaffected by BPA. The correlation between DLCO measured before BPA and P(Ai-a)O2 measured after BPA suggests that DLCO may provide an easily accessible marker to predict the response to BPA in terms of pulmonary gas exchange.
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Affiliation(s)
- Mathilde Blanquez-Nadal
- Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France; Université Grenoble Alpes, Grenoble, France
| | - Nicolas Piliero
- Service de Cardiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France
| | - Alicia Guillien
- Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France; Épidemiologie environnementale appliquée à la reproduction et à la santé respiratoire, INSERM, CNRS, Université Grenoble Alpes, Institut pour l'Avancée des Biosciences (IAB), Grenoble, France
| | - Stéphane Doutreleau
- Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France; Université Grenoble Alpes, Grenoble, France; Laboratoire HP2, INSERM U1042, Université Grenoble Alpes, Grenoble, France
| | - Muriel Salvat
- Service de Cardiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France
| | - Frédéric Thony
- Pole Imagerie, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France
| | - Christophe Pison
- Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France; Université Grenoble Alpes, Grenoble, France
| | - Caroline Augier
- Service de Cardiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France
| | - Hélène Bouvaist
- Service de Cardiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France
| | - Bernard Aguilaniu
- Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France; Université Grenoble Alpes, Grenoble, France
| | - Bruno Degano
- Service Hospitalier Universitaire Pneumologie Physiologie, Pôle Thorax et Vaisseaux, Centre Hospitalier Universitaire Grenoble Alpes, Grenoble, France; Université Grenoble Alpes, Grenoble, France; Laboratoire HP2, INSERM U1042, Université Grenoble Alpes, Grenoble, France.
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