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Physiology Related to Special Environments
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
Oxygen toxicity can occur if the inspired oxygen tension exceeds 1350 mmHg (180 kPa or 1.8 bar), as at a depth of 8 msw when 100% oxygen is inspired. Symptoms of oxygen toxicity include vertigo, paraesthesia of the arms and legs and muscle twitching around the mouth and eyes, progressing to convulsions. Pulmonary oxygen toxicity can develop at a depth of 16 msw when compressed air is inspired, with an inspired oxygen concentration of 375 mmHg (50 kPa or 0.5 bar). The first sign of pulmonary oxygen toxicity is dyspnoea, and pulmonary oedema and intra-alveolar haemorrhage are seen later. These symptoms usually occur after 30 hours of exposure to high inspired oxygen tensions. The latency of onset decreases with higher inspired oxygen tensions so that symptoms occur after 5 hours if the inspired oxygen tension is 1500 mmHg (200 kPa or 2 bar).
Dietary supplements and food fortification
Published in Geoffrey P. Webb, Nutrition, 2019
Babies born prematurely before their lungs are fully developed often need mechanical ventilation and/or an oxygen-enriched atmosphere. Excess oxygen exposure can cause oxygen toxicity which may lead to lung damage (bronchopulmonary dysplasia), eye damage (retinopathy of prematurity) and even brain damage. These conditions have often been attributed to damage caused by excess oxygen free radicals and have even been classed as a single disease “oxygen radical disease in neonatology”. Neonatal units now try to regulate the oxygen given to premature and sick babies so as to try and get a balance between the benefits and harm of extra oxygen. Giving an antioxidant, like vitamin E would seem like a logical preventative measure if these conditions are really caused by oxidative damage. A meta-analysis of 26 clinical trials suggested that giving pharmacological doses of vitamin E to very low birthweight babies may have beneficial effects but is not without risks especially if high intravenous doses are used. Despite the general belief that antioxidant systems are not fully developed in premature babies, WHO guidelines do not support routine supplementation with vitamin E.
Nutrition and the Lung
Published in Lourdes R. Laraya-Cuasay, Walter T. Hughes, Interstitial Lung Diseases in Children, 2019
Little is known about malnourishment and the antioxidant defense system in the human. The very early premature infant (<1500 g) is susceptible to pulmonary oxygen toxicity bronchopulmonary dysplasia.56 The antioxidant defense system of the premature newborn is probably not mature, if the findings from animal studies can be extrapolated to humans.57 Also, these premature infants are likely to be pulmonary surfactant deficient.58 Such problems can only be worse in the malnourished child. Rat pups born at 75% normal birth weight show significant acceleration of O2-induced lung injury.59 It is clear that further work is necessary to clarify the role of malnutrition in the premature infant.
The Effects of Ischemia and Hyperoxygenation on Hair Growth and Cycle
Published in Organogenesis, 2020
Harunosuke Kato, Kahori Kinoshita, Natsumi Saito, Koji Kanayama, Masanori Mori, Natsumi Asahi, Ataru Sunaga, Katsutoshi Yoshizato, Satoshi Itami, Kotaro Yoshimura
Hyperbaric oxygenation has been clinically used for some pathological conditions, but this approach can lead to cellular dysfunction due to oxygen toxicity and cannot be applied for more than 2 hours.9–11 The relation between oxidative stress and androgenic alopecia is also reported.12 Therefore, rather than hyperbaric hyperoxygenation, we used normobaric hyperoxygenation (NBO) as a treatment to improve hair growth and cycles. We previously compared the partial pressure of O2 in various organs and tissues by housing mice under 20% or 60% O2 and found that long-term application of 60% NBO is safe and maintain partial pressure of O2 in skin at 178% compared to room air.13 In this study, we sought to clarify the influence of ischemia and oxygenation on hair growth and hair cycle.
Treatment and respiratory support modes for neonates with respiratory distress syndrome
Published in Expert Opinion on Orphan Drugs, 2020
Theodore Dassios, Hemant Ambulkar, Anne Greenough
Closed loop automated oxygen control systems automate the adjustment of the inspired oxygen concentrations according to the peripheral oxygen saturation levels. The systems continuously monitor peripheral capillary oxygen saturation (SpO2) and the data are fed into an algorithm which determines the appropriate adjustment to the FiO2 which is then executed. The results of the adjustment are monitored and further changes made if needed. A review of 18 studies demonstrated that closed loop automated oxygen control was associated with an increased percentage of time spent within the target oxygen saturation range and fewer manual adjustments to the inspired oxygen concentration that when manual oxygen control alone was used [131]. Systems have been shown to be effective with invasive and noninvasive forms of respiratory support for preterm neonates. There are, however, no long data are available to determine whether such systems reduce the complications of oxygen toxicity.
Effects of long term normobaric hyperoxia exposure on lipopolysaccharide-induced lung injury
Published in Experimental Lung Research, 2020
Jick Hwan Ha, Sei Won Kim, In Kyoung Kim, Chang Dong Yeo, Hyeon Hui Kang, Sang Haak Lee
Prolonged exposure to hyperoxia is well known to cause oxygen toxicity and lung damage, particularly in animal models.10,12,13 Prolonged breathing of high oxygen levels causes hyperoxic acute lung injury, the severity of which is directly proportional to the inspired O2 fraction (FiO2) and duration of exposure.9 Most animals typically die after 3–6 days with respiratory failure under conditions of FiO2 ≥ 0.9–1.0.21 Several experiments have shown that oxygen toxicity rises more rapidly as FiO2 increases above 0.6 and exposure time is prolonged.9 However, few studies have been conducted on humans and there is no clear evidence that exposure to hyperoxia is toxic.11,15,16