Chest
Contemporary Reviews in Critical Care MedicineHeated Humidified High-Flow Nasal Oxygen in Adults
Section snippets
Search Criteria
We searched for publications and abstracts on PubMed, the Cochrane Database of Systematic Reviews, and Scopus using the search terms “high flow” OR “humidified” OR “heated” AND “oxygen therapy” OR “nasal oxygen.” We limited the search to English-language publications but did not limit the search based on publication type. We searched for both bench studies and adult human studies. We considered only studies defining nasal high flow as a flow rate ≥ 20 L/min.
Potential Mechanisms of Clinical Benefit
HFNC consists of high-flow gas with an Fio2 ranging from 0.21 to nearly 1.0 adjusted by an oxygen blender, brought to body temperature, and saturated with water through an in-line humidifier. The gas mixture is then provided to the nares through loose-fitting nasal prongs that are slightly larger but softer than those used for standard nasal oxygen therapy. The mechanisms by which HFNC may offer advantages to patients with dyspnea and hypoxemia are shown in Table 1.
Hypoxemic Respiratory Failure
HFNC has been tried in a number of different types of hypoxemic respiratory failure (Table 2). Initially, a few anecdotal cases were reported on the comfort and oxygenation advantages of HFNC in respiratory failure and during procedures such as bronchoscopy in patients with hypoxemia.44, 49, 50, 51 Two retrospective analyses showed significant improvement in oxygenation and reduction in respiratory rate in adult burn patients52 and in a surgical high-dependency unit.53
In 2010, Roca et al5
Possible Role for HFNC in the Treatment of Hypoxemia and Respiratory Failure
Based on the multiple physiologic and subjective benefits of HFNC compared with standard oxygen therapy, HFNC is assuming a role in the management of hypoxemia and respiratory failure. The greatest benefit appears to be in patients who have severe hypoxemia and would ordinarily receive standard high-flow oxygen therapy by mask. For these patients, HFNC offers enhanced comfort, more-reliable delivery of Fio2, and more-efficient ventilation. HFNC is unlikely to benefit patients with more mild
Practical Application
Because of the limited clinical data available for adult applications of HFNC, it is difficult to make firm recommendations on practical aspects of HFNC use. Physiologic studies have demonstrated that the beneficial effects of HFNC are related to flow rate, so we prefer to initiate therapy by adjusting this parameter first and then to titrate the Fio2 to maintain target oxygenation. Flow rates on commercially available devices range from 5 to 60 L/min. Studies in the literature have started
Conclusions
Devices that deliver high-flow heated and humidified oxygen through nasal cannulae (HFNCs) have become a standard of care in several clinical situations for infants, children, and preterm neonates. By virtue of a number of physiologic benefits over conventional oxygen therapy, including greater comfort and tolerance, more-effective oxygenation in some circumstances, and improved breathing pattern with increased tidal volume and decreased respiratory rate and dyspnea, we are now seeing
Acknowledgments
Financial/nonfinancial disclosures: The authors have reported to the following conflicts: Dr Hill has served on the Medical Advisory Board and received consulting fees from Fisher Paykel and has also received consulting fees from Vapotherm. Drs Spoletini, Alotaibi, and Blasi have reported that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.
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