We searched PubMed for articles published in English between Dec 20, 2005, and Dec 17, 2015. We used the search terms “oxygen” in combination with “cannula” and “high flow”; “heliox” in combination with “humans” or “helium” in combination with “oxygen” and “humans”; “hypoxemia” in combination with “nitric oxide” and “humans”; “mechanical ventilation”, “respiratory failure”, or “hypoxemia” in combination with “epoprostenol”, “prostacyclin”, “veletri”, or “iloprost”, in combination with
SeriesHigh-flow oxygen therapy and other inhaled therapies in intensive care units
Introduction
Respiratory diseases account for a large portion of admissions to the intensive care unit. The lungs are unique both in their exposure to the outside environment and as a part of the cardiopulmonary circuit, exposed to the entirety of the body's circulation. Given these attributes, it is logical that inhaled therapies function as treatments for a range of conditions encountered in critical care. Various devices and drug formulations have been developed to specifically target the lung parenchyma, vasculature, and airways. In this Series paper, we discuss the current evidence regarding the use of inhaled therapies in critical care, including high-flow nasal cannulae (HFNC), heliox, nitric oxide, prostacyclins, bronchodilators and steroids, and antibiotics. We systematically searched the literature to provide the basis for this Series paper.
Section snippets
HFNC
The traditional nasal cannulae for oxygen administration is typically used at flows of 2–4 L/min. At these low flows, large dilution occurs with room air and thus the fraction of inspired oxygen (FiO2) is less than 0·4 L/min. Flows greater than 6 L/min can cause much discomfort when breathing in dry oxygen. Unheated bubble humidifiers can be used, but are inefficient and their efficiency decreases with increases in flow. Systems to deliver heated and humidified oxygen at flows as high as 60
Heliox
Helium is a non-toxic noble gas with a density of 0·18 g/m3, which is much lower than oxygen (1·43 g/m3) and nitrogen (1·25 g/m3).24 Heliox is a mixture of helium and oxygen (usually in a helium:oxygen ratio of 80:20 or 70:30). This gas has been used for decades in the care of patients with various respiratory diseases, albeit with little evidence to guide its use. Its low density affords heliox a unique niche in the critical care setting, with potential applications for partial upper airway
Inhaled nitric oxide for hypoxaemic respiratory failure
Nitric oxide (NO) is a colourless and odourless gas, known to be an environmental pollutant and a toxic component of cigarette smoke. NO is formed endogenously in endothelial cells from L-arginine, catalysed by the enzyme NO synthase. In 1987, NO was identified as the molecule that was previously known as endothelial-derived relaxing factor. Shortly thereafter, studies in both animals and people reported that NO, when inhaled, could decrease pulmonary vascular resistance in patients with
Inhaled prostacyclins for hypoxaemic respiratory failure
Endogenous prostacyclin produced by endothelial cells is a prostaglandin in the eicosanoid group of lipids. It functions as an inhibitor of platelet activation and as a vasodilator. Prostacyclin upregulates cyclic AMP (cAMP), triggering smooth muscle relaxation and subsequent vasodilation (figure 4).63, 64 Intravenous synthetic prostacyclin analogues have a non-selective vasodilatory effect and have long been used to treat pulmonary hypertension. Inhaled prostacyclins have a more specific
Inhaled bronchodilators and corticosteroids during mechanical ventilation
Inhaled bronchodilators, including short-acting β agonists (SABAs) and short-acting muscarinic antagonists (SAMAs), have a role in the care of mechanically ventilated patients with reversible airflow obstruction. Results of a 2016 international survey78 indicated that 22% of intubated patients received aerosol therapy, most commonly bronchodilators and steroids.78 Although commonly prescribed, a dearth of evidence is available examining the effectiveness and safety of bronchodilators in this
Aerosolised antibiotics during mechanical ventilation
Aerosolised antibiotics are standard practice for treatment of Pseudomonas aeruginosa infection in patients with cystic fibrosis.93 Ventilator-associated tracheobronchitis and ventilator-associated pneumonia are common in intubated mechanically ventilated patients. There is renewed interest in the use of aerosolised antibiotics for ventilator-associated pneumonia and ventilator-associated tracheobronchitis, fuelled by the emergence of multidrug-resistant pathogens, most often Gram-negative
Conclusions
Although inhaled therapies greatly vary in their use in the intensive care unit, their ability to directly target the lungs in various conditions while potentially avoiding adverse systemic events makes them attractive for treatment purposes. Despite this, evidence regarding their use in the intensive care unit has been scarce. Our recommendations for use of inhaled therapies are in table 2. Given the few proven therapies in highly morbid conditions (eg, ARDS, ventilator-associated pneumonia,
Search strategy and selection criteria
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Cited by (44)
Oxygen as an Essential Medicine
2022, Critical Care ClinicsCitation Excerpt :Over the last 2 decades, the use of HFNC systems that provide heated and humidified flows up to 60 L per minute and supply oxygen concentrations greater than 90% has grown exponentially.25 Because of the increased flow rates intrinsic to these delivery systems, there is a reduced entrainment of room air, a washout of carbon dioxide with high oxygen concentrations, and small increases in mean airway pressure, providing an effective method of increasing arterial oxygen concentration.26,27 Providing supplemental oxygen through the use of HFNC devices has been shown to reduce the risk of intubation and death in patients with AHRF,28 as well as reduce the risk of reintubation in patients who were liberated from invasive mechanical ventilation when compared with conventional oxygen therapy.29
Effectiveness of high-flow nasal cannula on pulmonary rehabilitation in subjects with chronic respiratory failure
2022, Respiratory InvestigationLines of Treatment of COVID-19 Infection
2021, Covid-19 Infection and PregnancyAdministration of inhaled noble and other gases after cardiopulmonary resuscitation: A systematic review
2020, American Journal of Emergency MedicineCitation Excerpt :It has a low density that facilitates transition of small airway gas flow from turbulent to laminar. [55] Therefore, heliox at a He/O2 ratio of 80:20 or 70:30 is used in clinical practice for decreasing the work of breathing during airway obstruction, particularly in upper airway disease [56]. As noted above, inhalation of 50% He did not protect the CA1 sector of the rat hippocampus from damage [48].
Emergency tracheal intubation in 202 patients with COVID-19 in Wuhan, China: lessons learnt and international expert recommendations
2020, British Journal of AnaesthesiaCitation Excerpt :High-flow nasal cannula oxygen is used increasingly to treat acute respiratory failure before invasive ventilation,47–49 and has been used in COVID-19 patients.3 This approach reduces intubation rate in acute respiratory failure.48,50 It is still controversial whether HFNO increases virus aerosol spreading.