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Physiology of the Airways
Published in Anthony J. Hickey, Sandro R.P. da Rocha, Pharmaceutical Inhalation Aerosol Technology, 2019
Anthony J. Hickey, David C. Thompson
Spirometry is the measurement of the volume of air moving into or out of the airways. In this process, various ventilatory maneuvers are undertaken that permit an estimation of pulmonary volumes and capacities (Figure 2.6). Such measurements are valuable for diagnosis of airway disease because pathological conditions can modify specific pulmonary volumes. Definitions of the specific lung volumes are provided in Table 2.4. Measurements of lung volumes are generally normalized for a subject’s body size (weight, height, or surface area), age, and gender. This process permits a comparison with standardized or predicted lung volumes, thereby allowing identification of lung pathophysiologies using a simple procedure. Some examples of the way in which airway disorders alter lung volumes are described in the following. During an episode of airway obstruction (as in asthmatic bronchospasm), expiration of air is difficult, and air becomes trapped in the lower airways. This results in an increase in the residual volume and functional residual capacity and a decrease in vital capacity. In conditions that adversely affect respiratory muscles, such as poliomyelitis or spinal cord injuries, voluntary control of inspiratory or expiratory movement is diminished (or absent) and vital capacity is reduced.
Drug-induced acute upper airway obstruction
Published in Philippe Camus, Edward C Rosenow, Drug-induced and Iatrogenic Respiratory Disease, 2010
Michael Lippmann, Ganesan Murali
Upper airway obstruction is usually seen in the setting of an infectious process such as epiglotitis, inflammation, trauma, haemorrhage or a neoplasm. However, in the last few decades it has been recognized that various drugs and anaesthetics can be associated with severe airway compromise (Box 7.1). The groups of drugs known as angiotensin-converting enzyme inhibitors (ACEIs), agents that have been shown to reduce mortality from heart failure, are by far the most common class of drugs associated with this complication.1 In this chapter we will review the incidence, clinical manifestations, treatment and outcome of patients with drug-induced upper airway obstruction.
Pesticides and Chronic Diseases
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
In animals treated with 1 × LD50 sarin, both superficial layers (I–III) and deeper layers (IV–V) of the motor cortex and somatosensory cortex showed degeneration of neurons. In the deeper layers of the cortex, neuron degeneration was seen in layer V. Pyramidal neurons in layers III and V of the cortex are the source of the axons of the corticospinal tract, which is the largest descending fiber tract (or motor pathway) from the brain controlling movements of various contralateral muscle groups. Thus, sarin-induced death of layers III and V neurons of the motor cortex could lead to considerable motor and sensory abnormalities, ataxia, weakness, and loss of strength. Furthermore, disruption of the hippocampal circuitry because of the degeneration of neurons in different subfields can lead to learning and memory deficits. Lesions in the cerebellum could result in gait and coordination abnormalities which we often see in the severe chemically sensitive patient as seen in the autistic and other individuals with chemical sensitivity. Since the severely affected areas (e.g., the limbic system, corticofugal system, and central motor system) are associated with mood, judgment, motion, posture, locomotion, and skilled movements, humans exhibiting acute toxicity symptoms following exposure to large doses of OPs may also develop psychiatric and motor deficits. Inasmuch as the severely damaged areas of the brain do not usually regenerate, these symptoms are expected to persist long-term.322–324 However, recent studies with pain in patients suggests that the brain can shrink one-third with pain and then expand where the pain is relieved. These findings are in agreement with a recent study by Kilburn325 who evaluated the neurobehavioral effects of chronic low-level exposure to the organophosphorus insecticide chlorpyrifos in 22 patients. Kilburn demonstrated an association between chlorpyrifos sprayed inside homes and offices and neurophysiological impairments in balance, visual fields, color discrimination, hearing reaction time, and grip strength. These patients also had psychological impairment of verbal recall and cognitive function, and two-thirds of them had been prescribed antidepressant drugs. In addition, the patients exhibited severe respiratory symptoms, accompanied by airway obstruction. Other chlorpyrifos-induced neurotoxicity incidents in humans have been reported.326 These results are consistent with the report that daily dermal application of 0.1 mg/kg chlorpyrifos to adult rats resulted in sensorimotor deficits.327 Also, material exposure to a daily dermal dose of 0.1 mg/kg chlorpyrifos during gestational days 4–20 caused an increased expression of GFAP in the cerebellum and hippocampus of offspring on postnatal day 30.328 A major component of astrocytic intermediate neurofilaments, GFAP is upregulated in response to reactive gliosis resulting from insults such as trauma, neurodegenerative disease, and exposure to neurotoxicants.329
Design of 4D printed shape-changing tracheal stent and remote controlling actuation
Published in International Journal of Smart and Nano Materials, 2021
Fenghua Zhang, Nan Wen, Linlin Wang, Yunqi Bai, Jinsong Leng
The trachea can keep the respiratory tract unobstructed [32], but the trachea is very fragile and vulnerable to various diseases [33–35]. As a common critical disease, airway stenosis is the main airway restriction caused by airway obstruction, which can cause dyspnea and even endanger the life of patients. However, due to the fragility and special structure of the trachea, it is difficult to repair the injured trachea [36–39]. Till now, endotracheal stent intervention is the most common and effective treatment of tracheal stenosis. In this process, the stent is implanted into the narrow trachea to reshape the diameter of the trachea, quickly relieve the airway stenosis and relieve the symptoms of dyspnea. NiTi shape memory alloy tracheal stent are commonly used in clinic. The main disadvantages of NiTi stents are difficult reduction, easy to cause tracheal obstruction if collapse occurs. In addition, it is difficult to remove after implantation. Moreover, tumor or granulation growth is easy to pass through the mesh. In view of the shortcomings of the above shape memory alloy tracheal stent, the shape memory PLA composite tracheal stent was designed with SMP as material, and the collapse of the stent was repaired with SMP of the stent. The degradability of SMP makes it unnecessary to remove the stent. Combined with 4D printing, the shape memory tracheal stent with complex and optimized structure can be customized.
Computational modeling of child’s swallowing to simulate choking on toys
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2020
Yukihiro Michiwaki, Takahiro Kikuchi, Tetsu Kamiya, Yoshio Toyama, Motoki Inoue, Keigo Hanyuu, Megumi Takai, Seiichi Koshizuka
At the start of swallowing, the soft palate lifted upward. On the other hand, the tongue started a progressively wave-like movement as its concaved section gradually progressed backward, while the toy ball was transported to the pharynx. The epiglottis rotated downward to cover the larynx and preserve the airway (Figure 4(d)). The ball entered even deeper in the pharynx to rest on the rotated epiglottis. The toy ball of 15 mm in diameter not only occupied the airway in the pharynx but also made the epiglottis cover the larynx, causing total airway obstruction (Figure 4(e)). The airway obstruction induces choking or asphyxia, which causes death or severe damage due to hypoxia.