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Emergency Medicine
Published in Stephan Strobel, Lewis Spitz, Stephen D. Marks, Great Ormond Street Handbook of Paediatrics, 2019
Key in the management are generous humidification and physiotherapy to mobilise secretions and mucus plugs (Figs 1.13, 1.14). Drug treatment may include continued neuromuscular paralysis, ketamine by continuous infusion (for both sedative and bronchodilator effect), IV bronchodilators, corticosteroids and antibiotics. Heliox (a mixture of oxygen and helium with a lower density than air) has been used to ventilate patients with very high airway resistance but has not been widely adopted. Weaning from mechanical ventilation can be difficult. Any child requiring admission to a paediatric intensive care unit (PICU) for acute severe asthma should be referred to a paediatric respiratory specialist for out-patient follow up on hospital discharge.
Surfactant aerosol therapy for nRDS and ARDS
Published in Anthony J. Hickey, Heidi M. Mansour, Inhalation Aerosols, 2019
Heliox is a mixture of helium and oxygen, most often 80% helium and 20% oxygen, with other mixtures containing higher percentages of oxygen being available. When patients with compromised lung function breathe heliox, the work associated with breathing is reduced and gas exchange improves due to the decreased flow resistance resulting from the lower density of helium compared to air and the decrease in turbulence. As the viscosity of heliox and air are similar, the ratio of the inertial forces compared with the viscous forces is markedly lower for heliox than air. The clinical, physiologic benefits of using heliox compared to air are as follows: Low Reynolds number leads to less turbulence in the conducting airways (98)Decreased work of breathing (114)Reduction of airway inflammation (115,116)Improvement of oxygenation and CO2 removal (118)Increased peripheral aerosol penetration (118,119)
Upper Airway Obstruction and Tracheostomy
Published in John C Watkinson, Raymond W Clarke, Terry M Jones, Vinidh Paleri, Nicholas White, Tim Woolford, Head & Neck Surgery Plastic Surgery, 2018
The inspiratory oxygen concentration can be increased with the administration of high-flow oxygen via a facemask with a reservoir bag. In the emergency situation, the use of oxygen can be combined with simple airway methods including chin lift and jaw thrust. Use of humidification helps to break down secretions and makes them easier to clear. Heliox is a mixture of 80% helium with 20% oxygen. The properties of helium are a gas with low density and high viscosity resulting in less turbulence compared with air and pure oxygen. The patient experiences reduced resistance during breathing heliox and this is of proven benefit in the obstructed patient.1
Investigation of airflow at different activity conditions in a realistic model of human upper respiratory tract
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Reza Tabe, Roohollah Rafee, Mohammad Sadegh Valipour, Goodarz Ahmadi
Another interesting and important subject in the respiratory airway is the analysis of wall shear stress. It can help to recognize physiological changes to the values of stresses that are applied to the respiratory epithelial lining. In the study of Elad et al. (2006), two significant clinical observations in the nasal passages were seen. Their results showed that high shear stress at particular regions causes a chronic tension-type headache. Also, after rhinoplasty surgery, clogged noses are usually reported which can be attributed to a decreasing of the cross-sectional area of the nasal valve with the secondary elevation of nasal wall shear stress. Because shear stresses are changed linearly with local velocity, these values augment notably with increasing inspiration efforts. Investigations of Kim et al. (1997) and Rogers (1994) have indicated discharge mucous secretion in response to wall shear stresses. Also, locally high shear stresses may cause irritation of the blood vessels. Evaluation of the effect of heliox, a helium/oxygen mixture, on the respiratory system has been studied in various studies (See Jolliet et al. 2016; Pozin et al. 2017; Paxman et al. 2019).
Pharmacotherapeutic strategies for critical asthma syndrome: a look at the state of the art
Published in Expert Opinion on Pharmacotherapy, 2020
Alessandro Vatrella, Angelantonio Maglio, Corrado Pelaia, Girolamo Pelaia, Carolina Vitale
In order to reduce respiratory work and improve ventilation, a mixture of oxygen and helium (heliox) has been introduced in clinical practice, since the lower density of helium reduces the resistance to airflow in turbulent flow conditions [92,94]. A systematic review with meta-analysis of randomized trials designed to evaluate the efficacy of heliox versus oxygen in driving b2-agonist nebulization in patients with acute asthma suggests that heliox benefits in airflow limitation and hospital admissions could be considered clinically significant [95]. Furthermore, heliox has proven to be quite useful in pairs with bronchodilator therapy, as it appears to be able to make superior functional improvements compared to bronchodilator therapy alone [96,97]. Despite these encouraging data, at the moment, GINA guidelines suggest there is no role for this intervention in routine care, but it may be considered for patients who do not respond to standard therapy [1].
Overview of prevention and management of acute bronchiolitis due to respiratory syncytial virus
Published in Expert Review of Anti-infective Therapy, 2018
Helium is an inert gas, and its density is almost 15% that of air. Carbon dioxide (CO2) is more diffusible through helium than air. Helium inhalation results in maintenance of more laminar gas flow and decreases turbulence through narrowed airways, which subsequently lowers resistance to gas flow. Therefore, breathing heliox decreases airway resistance and reduces work of breathing [69,70]. Heliox has been shown to improve oxygenation in respiratory illness with moderate to severe airway obstruction, including in AVB [71]. A meta-analysis of four clinical trials (with 84 participants) using heliox, demonstrated improved respiratory distress scores in the first hour of its use in children with moderate to severe AVB. However, heliox inhalation did not affect need for intubation and mechanical ventilation and LOS in the pediatric intensive care unit [31,72]. The routine use of heliox is, therefore, not currently recommended.