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Noninvasive Tests Involving the Input of Audible Sound Energy
Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017
It is well known that various anatomical and physical changes happen to the bronchioles and alveoli of the lungs in obstructive lung diseases (e.g., asthma, atelectasis, byssinosis, cystic fibrosis, emphysema, pneumonia, silicosis, asbestosis, tuberculosis, etc.). These changes alter the acoustic impedance of the lungs as measured orally through the tracheal airway. For example, in emphysema, the walls separating adjacent alveoli break down, producing larger alveolar spaces with walls having less elasticity. In cystic fibrosis, the alveoli and bronchioles become clogged with mucus, increasing airway resistance and reducing lung volume, etc. Different physical changes in lung tissues will lead to different ZA(jω) plots. Hereafter, we will refer to the ZA of the respiratory system “seen” through the pharynx and trachea as Zrs.
Oxygen Delivery and Acute Hypoxia: Physiological and Clinical Considerations
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
Oxygen administration may also lead to absorption collapse. Alveolar gas normally contains about 80 per cent nitrogen, and when this is replaced by oxygen, alveolar gas may be absorbed into the blood faster than it is replaced in regions of the lung with low ventilation–perfusion ratios. In aviation, a similar problem occurs in pilots when they are subjected to +Gz acceleration forces, as airways in dependent areas of the lung close. This ‘acceleration atelectasis’ is much more likely to occur when high inspired oxygen concentrations (> 70 per cent) are used and it may lead to chest pain, dyspnoea and coughing (Tacker et al., 1987). Other problems associated with oxygen administration are specific to particular patient groups. In premature babies, complications associated with oxygen therapy include retinopathy (retrolental fibroplasia) and bronchopulmonary dysplasia. Retinopathy of prematurity can follow even quite brief periods (a few hours) of hyperoxia (Sola, 2008).
Radiation-induced lung disease
Published in Philippe Camus, Edward C Rosenow, Drug-induced and Iatrogenic Respiratory Disease, 2010
Max M Weder, M Patricia Rivera
Endobronchial brachytherapy is mainly used as an adjunctive palliative treatment of symptoms related to endobronchial tumour growth. In the usual setting, continuous growth of a primary lung cancer causes endobronchial obstruction. Much less commonly, endobronchial obstruction is caused by metastatic disease. Symptoms are mainly related to tumour erosion of the endobronchial vasculature and atelectasis with possible post-obstructive pneumonia and include cough, dyspnoea, haemoptysis and fever. In cases of severe obstruction, endobronchial brachytherapy is usually preceded by procedures directed at immediate alleviation of the obstruction, such as endobronchial laser or cryotherapy, electrocauterization and endoluminal stent placement.37 Endobronchial brachytherapy may then be employed to achieve long-term control of the obstruction.
Lung volume reduction with endobronchial valves in patients with emphysema
Published in Expert Review of Medical Devices, 2018
Marieke C. Van Der Molen, Karin Klooster, Jorine E. Hartman, Dirk-Jan Slebos
The most common complication after EBV treatment is a pneumothorax of the ipsilateral, untreated lobe. Volume reduction of the treated lobe causes rapid expansion of the untreated lobe, resulting in a rise in negative intrapleural pressure and can cause the lung tissue to rupture in the presence of adhesions and subpleural bullae. A pneumothorax is most frequently seen in patients with a complete atelectasis following EBV treatment and has no negative impact on clinical outcomes [49–51]. Therefore, pneumothoraces should rather be seen as a consequence of EBV treatment than a complication. In the more unusual case of a pneumothorax originating from the target lobe, the pneumothorax is mostly asymptomatic and accompanied by a persistent volume reduction of the treated lung despite the pneumothorax being present: the so called ‘pneumothorax ex vacuo’ [52]. In this case, no additional treatment is required.
Aesthetic reconstruction of microtia: a review of current techniques and new 3D printing approaches
Published in Virtual and Physical Prototyping, 2018
Maureen T. Ross, Rena Cruz, Courtney Hutchinson, Wendy L. Arnott, Maria A. Woodruff, Sean K. Powell
Tanzer (1959) developed the technique of carving autogenous costal cartilage in the 1950s which was a major revolution in the field of auricular reconstruction. This method of reconstruction is still regarded as the gold standard for microtia; however, it is also considered one of the most difficult operations in plastic surgery (Sabbagh 2011, Kludt and Vu 2014, Zhao et al. 2016). Brent (1999) and Nagata (1994a, 1994b, 1994c) pioneered current methods for autografting. Brent’s technique is a three or four stage process, which harvests less cartilage than the Nagata technique, therefore allowing for younger children to undergo the surgery (eight to nine years old) (Brent 1999, Kelley and Scholes 2007, Sabbagh 2011, Storck et al. 2014). The Nagata technique requires fewer stages, however, the technique is more challenging as it requires additional carving of the cartilage which forms the ear, plus it requires patients to be 10 years old with a minimum chest circumference at the xyphoid of 60 cm (Kelley and Scholes 2007, Baluch et al. 2014). Due to the invasive nature of surgery, these techniques present risks of infection and donor site complications including pneumothorax, atelectasis, scarring, thoracic scoliosis and chest-wall deformity (Romo and Reitzen 2008, Puppi et al. 2010, Kludt and Vu 2014, Park et al. 2016). It should also be noted that there are biochemical differences between auricular (elastic) cartilage and rib (hyaline) cartilage, with rib cartilage being much more rigid (Xu et al. 2005, Otto et al. 2015, Zhao et al. 2016).
Parameters of high-frequency jet ventilation using a mechanical lung model
Published in Journal of Medical Engineering & Technology, 2022
Evgeni Kukuev, Evgeny Belugin, Dafna Willner, Ohad Ronen
Our study hads several limitations. The main limitation was posed by the use of a mechanical lung model, which may not accurately simulate real lungs. While an experimental lung model does provide insight into lung mechanics, it does not include the influence of pulmonary diseases, thoracic cage, and effects of gravity on pulmonary physiology. While the lung model was designed to simulate conditions in conventional ventilation, it might not be ideal for measurement of the flow physics characteristic of high-frequency jet ventilation. Further, the changing compliance in an experimental lung model may not represent a diseased lung or represent a lung with alveoli of different time constants. Side effects and complications of high-frequency jet ventilation such as atelectasis, hypotension, right ventricle failure, over-inflation, air trapping and air leak/pneumothorax, cannot be observed with in-vitro experiments, and higher alveolar pressure might be measured in a live model. Pressure gradient is greatest in the small airways, which are absent in the lung model. On the other hand, the strength of a lung model lies in its ability to change one parameter at a time while controlling for all others, enabling assignment of observed phenomenon to specific parameters. The model might accurately represent the measurements of minute volume since it depends on the physical properties of the lung, yet some elements missing in the model such as small bronchi, mucus, and bronchi smooth muscle contractions. In a specific individual patient, where all the above parameters are mostly constant, the results of this study should apply.