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Pulmonary Evaluation and Management of Early-Onset Scoliosis
Published in Alaaeldin (Alaa) Azmi Ahmad, Aakash Agarwal, Early-Onset Scoliosis, 2021
Laura Ellington, Mary Crocker, Gregory Redding
The chest wall deformity also leads to reduced lung volumes and local distortion of lung shape, as illustrated in Figure 5.1. Loss of lung volume regionally or generally leads, in turn, to reduced lung compliance, contributing to respiratory system stiffness. Loss of lung volume also predisposes patients with EOS to recurrent hypoxaemia during sleep when pauses in breathing occur [3]. This occurs because some airways are narrowed with reduced functional residual capacity (FRC) and close with relaxation of thoracic muscles during rapid eye movement (REM) sleep. These are called hypopnoeic hypopxaemic episodes during sleep and differ from obstructive apnoeas that are more prolonged and due to upper airway obstruction or collapse. In children with large tonsils and adenoids, obstructive sleep apnoea and recurrent hypoponeic hypoxemic events can coexist and disturb sleep quality.
Mechanical Properties of the Lungs
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Lung compliance is the change in volume produced by a unit change in the expanding transpulmonary pressure. It is a measure of ease of distensibility or stretching of the lungs. The most important determinant of the elastic behaviour of the lung is the surface tension of the fluid lining the alveoli. Elastance is the reciprocal of compliance.
Neurointensive care: Postoperative management
Published in Hemanshu Prabhakar, Charu Mahajan, Indu Kapoor, Essentials of Geriatric Neuroanesthesia, 2019
With increasing age there is a reduction in elastic recoil of lungs, increasing lung compliance, and decrease in compliance of the chest wall. The functional residual capacity and residual volume gradually increase with aging. As the total lung capacity remains constant, there is decrease in vital capacity. Also, with aging there is a gradual decline in arterial oxygenation. There is reduced tidal volume and higher respiratory rate in the elderly in comparison to younger subjects. Response to hypoxia and hypercapnia decreases in old age. Cough reflex and swallowing also decline with aging. All these changes in old age cause increased work of breathing, atelectasis, infection, and risk of aspiration (2). The closing volume increases, leading to mismatch in ventilation/perfusion during tidal breathing in the supine position (3,4).
Pinealectomy and melatonin administration in rats: their effects on pulmonary edema induced by α-naphthylthiourea
Published in Drug and Chemical Toxicology, 2023
Mohammed Raed Abdullah Al Gburi, Eyup Altinoz, Hulya Elbe, Melike Ozgul Onal, Umit Yilmaz, Nesibe Yilmaz, Melike Karayakali, Mehmet Demir
Pulmonary edema is a clinical disorder leading to respiratory failure (Barile 2020). The disorder is observed due to the hydrostatic effect of elevated pulmonary vascular pressure and blood volume. The Alveolar-capillary membrane is an extremely thin structure that allows optimal gas exchange and serves as a barrier to fluid accumulation in the alveolar space, limiting the diffusion of solute volumes physiologically (Comellas and Briva 2009). There is a significant balance between alveolar fluid uptake and secretion in the maintenance of optimal gas exchange in the alveolar space. The alveolar-capillary membrane’s increased permeability allows the passage of fluid and protein into the interstitial fluid space and alveoli (Casey et al. 2019). Excessive accumulation of pleural fluid was described as pleural effusion (PE), which leads to a common problem induced by several mechanisms and disorders (Allibone 2006). Several lung diseases could be associated with PE. PE plays a key role in the respiratory system, especially the normal changes associated with age that compromise the respiratory system (Wing 2004). In particular, it reduces pulmonary gas exchange while leading to restriction of lung functions based on the fluid volume and the reduction in lung compliance (Ruiz et al. 2006).
Prevention of submicron aerosolized particle dispersion: evaluation of an aerosol box using a pediatric simulation model
Published in Experimental Lung Research, 2022
Laurence Tabone, Dominic Rivest, Arielle Levy, Michael Buyck, Philippe Jouvet, Carl-Eric Aubin, Tine François, Etienne Robert, Florent Baudin
To our knowledge, this is the first study evaluating generation of AP in spontaneous ventilation and NIV in a pediatric simulation model. Using a breathing simulator is crucial both for reproducibility of the breathing simulations and to control lung compliance. Indeed, Hui et al showed the impact of lung compliance on AP dispersion using a pediatric model, highlighting the specific lung and chest wall properties in children.26 Of course, this model does not perfectly reproduce the conditions under which AP are generated in humans. Even if the ventilation simulator could reproduce realistic ventilation mechanics, the degree of hygrometry and temperature of the human airways, which impact the size and displacement of the AP,2 could not be reproduced with this model. In addition, the level of AP produced by the aerosol generator in our simulated conditions is probably much higher than what a human would produce. For example, the concentration of exhaled particles in subjects with influenza A was in the range of 67–8500 per liter in one study.27 Our model essentially generated AP smaller than 1 micron. Although this does not account for the entire particle size range emitted during exhalations, the median mass of AP has been reported between 0.7 and 1 micron for exhalation28 and influenza RNA was found mainly in AP smaller than 1 micron in exhaled human breath.27 Thus, even if exhaled human particles containing SARS-CoV-19 have not yet been studied, the size of the generated AP by our model seems to be adequately estimated.
Inhalation dosimetry of nasally inhaled respiratory aerosols in the human respiratory tract with locally remodeled conducting lungs
Published in Inhalation Toxicology, 2021
Xiuhua April Si, Mohamed Talaat, Wei-Chung Su, Jinxiang Xi
At the current stage that CFD simulations with a whole lung geometry are still not feasible, an ideal method of considering lung compliance should include (1) the dynamic/kinematic properties of the respiratory tract model and (2) the compliance/resistance of the downstream lung periphery. Pathologies such as asthma and acute lung injury not only alter the structure of the lung but also its mechanical properties. These altercations can occur in different regions and at different extents, leading to considerable heterogeneity throughout the lung, and especially in the peripheral lungs (Bates and Suki 2008). Using an impedance model, Oakes et al. (2015) compared airflow and particle dynamics in the normal and emphysematous rat lungs by varying the downstream resistance and compliance as the outlet boundary conditions. Notably, the rat lung model retained 81 terminal airways (Oakes et al. 2012) and the compliance and resistance for the normal and emphysematous rat lungs were measured experimentally (Oakes et al. 2014). In the current study, 368 bronchiolar outlets were retained in the airway model and uniform pressures were adopted at these outlets because of the lack of resistance/compliance measurements at the distal bronchioles. The potential effects of impedance altercations and heterogeneity on airflow and inhalation dosimetry, however, await further investigations.