Positional and Restraint Asphyxia
Darrell L. Ross, Gary M. Vilke in Guidelines for Investigating Officer-Involved Shootings, Arrest-Related Deaths, and Deaths in Custody, 2018
The process of asphyxiation itself is the ultimate death of the individual and the associated failure of organ systems secondary to a lack of oxygen supply and delivery to the organs. This oxygen delivery to the body relies upon many factors. For the purposes of this chapter, the most crucial factor is that oxygen can get into the blood to be transported to the tissues. Oxygenation of the blood can be divided into two parts: (1) ventilation and (2) gas exchange. The first and foremost process of ventilation is defined by adequate amounts of gas being delivered from the outside environment to the lung tissue for proper oxygenation of blood to occur, while carbon dioxide is removed. The second process, gas exchange, assuming adequate air movement via ventilation is present, allows for adequate exchanging of oxygen into the blood and removal of carbon dioxide from the blood in the small capillary beds and alveoli in the lungs. Both of these processes must occur for oxygenation of the blood.
Flexible and Wearable Chemical Sensors for Noninvasive Biomonitoring
Daniel Tze Huei Lai, Rezaul Begg, Marimuthu Palaniswami in Healthcare Sensor Networks, 2016
Humans consume oxygen and release carbon dioxide by the exchange of gases in the lungs. Gas exchange takes place between millions of alveoli in the lungs and the capillaries that envelop them. The partial pressure of oxygen in arterial blood (PaO2) is known to reflect the severity of lung disorders such as pulmonary embolism or atelectasis. It is also used in the diagnosis, treatment and management of respiratory depression. This parameter is usually measured by obtaining blood from an artery. This involves puncturing an artery, often at the wrist, and drawing a small volume of blood with a syringe. Normally, PaO2 is kept within a range of 80 to 100 mmHg, and abnormal PaO2 values are seen in hypoxemia or hyperoxemia. At a PaO2 of less than 60 mmHg, supplemental oxygen should be administered. In premature neonates, it is especially important to monitor arterial oxygen levels continuously to ensure they are maintained at normal levels as these infants have immature cardiopulmonary systems.
The transport and exchange systems: respiratory and cardiovascular
Nick Draper, Helen Marshall in Exercise Physiology, 2014
The respiratory system supplies the oxygen required for cellular respiration. This refers to the use of oxygen by cells of the body to sustain life and results in the production of energy, water and carbon dioxide. Oxygen is the most important substance for sustaining life because of its role in respiration. It reaches the cells through three stages of ventilation or gas exchange. Pulmonary ventilation or breathing enables oxygen to enter the lungs and carbon dioxide to be expelled. Alveolar ventilationenables oxygen brought into the lungs via pulmonary ventilation to diffuse into the bloodstream and carbon dioxide to be exchanged. Once within the bloodstream, oxygen is transported to cells throughout the body. The final form of gas exchange, cellular ventilation, enables oxygen to diffuse across the plasma membrane and enter the cell for use within cellular respiration, and carbon dioxide to move from the tissue cells into the blood for eventual removal from the body by the lungs.
Mathematical analysis of oxygen and carbon dioxide exchange in the human capillary and tissue system
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Ahsan Ul Haq Lone, M. A. Khanday
The human respiratory system has two main functions: oxygen intake from the surrounding air to the body, and to exhale carbon dioxide from the blood to outside air. Those transfers are achieved through passive diffusion across a membrane which separates the gaseous air and the liquid blood, at an instantaneous rate by means of the difference in partial pressures, the area of the exchange surface, and its properties in terms of diffusion (Guyton and Hall 2011; West 2011). As this diffusion tends to reduce the partial pressure difference, a constant renewal must be made on both sides of the membrane. Renewal of air is achieved by the ventilation process, which consists of in periodic inspiration-expiration cycles that provide the inside of the lung with fresh air, whereas venous blood is periodically pumped onto the exchange zone by the heart. The exchange area is the boundary of a huge collection of small cavities (around 300 million units), called alveoli, which makes an exchange area of about 100 m2 (Guyton and Hall 2011; West 2011; Tortora and Derrickson 2012; Nunn 2013). Each of this alveolus is surrounded by a network of very small blood vessels, called capillaries, whose diameter is about 5–10 μm (Guyton and Hall 2011; West 2011). Gas exchange occur through the alveolar-capillary membrane, which is less than a micrometre wide (West 2011; Tortora and Derrickson 2012). The alveoli are connected to the outside world through the respiratory tract, which is an assembling of interconnected pipes following a dyadic-tree structure.
The outcomes of endoscopic myringoplasty: packing with gelatin sponge versus packing with nothing
Published in Acta Oto-Laryngologica, 2020
Dan Wang, Tongli Ren, Wuqing Wang
It is well known that the middle ear cavity can maintain the normal function of the middle ear only when maintaining a certain pressure [16]. This pressure is maintained by gas exchange. A study showed that gas exchange in the middle ear can be divided into four main pathways [17,18]: (1) gas exchange with the nasopharynx through the eustachian tube; (2) gas exchange with the blood through the mucous membrane; (3) gas exchange with the external auditory canal through the tympanic membrane; and (4) gas exchange with the inner ear through the round window membrane. This suggests that gas exchange can be performed in many ways. Therefore, whether the gelatin sponge in the tympanic cavity can achieve the desired supporting effect and whether the absence of gelatin sponge packing will cause tympanic membrane collapse and affect the healing of the tympanic membrane perforation are still unknown. These problems are clinical concerns. However, in group A, patients who did not receive gelatin sponge packing during the operation, tympanic collapse did not occur during the follow-up. We speculate that the four gas exchange pathways in the middle ear cavity replaced the support of the gelatin sponge, which maintains the pressure balance inside and outside the tympanic membrane to avoid collapse of the tympanic membrane. Adhesions between the residual tympanic membrane and the perichondrium and adhesion of blood may also play an important role in strong binding of the two membranes. However, there is a lack of research articles in this field.
Nanocrystals based pulmonary inhalation delivery system: advance and challenge
Published in Drug Delivery, 2022
Pengfei Yue, Weicheng Zhou, Guiting Huang, Fangfang Lei, Yingchong Chen, Zhilin Ma, Liru Chen, Ming Yang
The lungs are the organs that contact with the exchange of air between the organism and the outside world. They are divided into two main regions: the conducting airway region and the respiratory region. The airway is a continuous branch from the bronchi to the lungs and consists mainly of bronchi, bronchioles, and terminal bronchioles. As the bronchi continue to branch, the diameter of the tubes becomes smaller, the tube wall becomes thinner, and the structure of the tube wall changes gradually. The annular smooth muscles of the bronchi contract or relax under splanchnic nerves innervation and it is responsible for the regulation of airflow passage into the alveoli. This is the site where the lung tissue completes gas exchange consisting of respiratory bronchioles, alveolar ducts, lung sacs, and alveoli. The respiratory bronchiole is the transitional pipes between the pulmonary airway and the respiratory site. Each respiratory bronchiole branch is divided into 2–3 alveolar ducts. The alveolar sacs are the common opening of several alveoli and are connected to the alveolar ducts. The gut is the main site for the digestion and absorption of nutrients.
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