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Summary: Recent advances in the use of high flow nasal oxygen therapies

Topic: Mechanisms Of Action Overview

Wyatt K, Noel G, & Whittle J. Recent advances in the use of high flow nasal oxygen therapies. Frontiers in Med 2022; 1-7. DOI 10.3389/fmed.2022.1017965 

Wyatt and colleagues performed a review of current literature on the use of high flow nasal oxygen (HFNO) in Type I, II, III, and IV respiratory failure in adult and pediatric patients, across a range of clinical settings (emergency departments, intensive care units, outpatient, and procedural applications). The review concluded that HFNO is a valuable addition to the options available for management of respiratory distress, and may offer advantages (including portability, improved freedom of movement, the ability of patients to eat and speak during therapy, and the ability to admit such HFNO to a broader range of hospital units). The authors point out that there are two primary technologies which collectively make up HFNO: high-flow nasal cannula providing heated, humidified air at flow rates up to 70 Liters/min and an FiO2 from 21 to 100%, and high-velocity nasal insufflation (HVNI), which utilizes small-bore nasal cannulas with improved flush of anatomic dead space.  

The authors found that for Type I respiratory failure, HFNO is recommended over noninvasive positive pressure ventilation (NiPPV) for treatment of acute hypoxemic respiratory failure (AHRF) and strongly recommended for usage over conventional oxygen therapy (COT) during hypoxemic respiratory failure.  HFNO has shown comparable or improved performance as compared to NiPPV or COT for treatment of AHRF. HVNI has also been shown to be non-inferior to NIPPV for intubation within 72-hours of admission, among patients with all-cause respiratory distress presenting in the Emergency Department.  

Neonates/pediatric patients 

The authors conclude that among preterm or pediatric patients, studies have found no significant differences in treatment failure or intubation rates between HFNO and nCPAP or Bi-Level PAP. HFNO reduced the risk of skin breakdown and injury as compared to mask based non-invasive methods but more RCTs are needed. The authors acknowledge that little data exists to determine the effectiveness of HFNO in children with hypercapnia.  

COVID-19 respiratory failure 

The authors point out that specifically among patients with COVID-19 respiratory failure, HFNO-treated adults had significantly reduced need for intubation and reduced time to recovery, but HFNO was not associated with decreased LOS in the hospital or ICU, or reduced mortality. HFNO has been shown to pose a low risk of viral spread, and delivery with a surgical mask helps prevent aerosol dispersal. 

Type II respiratory failure 

The authors evaluated the use of HFNO in management of Type II respiratory failure and found HFNO provides some ventilatory and oxygenation support. HVNI specifically, was shown to have comparable efficacy to NIPPV in hypercapnic respiratory failure, with no significant difference in treatment failure or intubation rate. Finally, they conclude that although evidence for HFNO usage during COPD with hypercapnia is growing, more studies are needed. 

Type III respiratory failure 

For Type III respiratory failure, HFNO was given a conditional recommendation with moderate certainty by the European Society of Intensive Care Medicine for usage post-operatively in high-risk and obese patients after cardiac and thoracic surgery. The authors note that patients are also at risk for type III respiratory failure in the immediate post-extubation period, and that HFNO significantly reduced reintubation rates and post-extubation respiratory failure compared to COT and performed similarly to NIPPV.  

Type IV respiratory failure 

Type IV respiratory failure occurs due to failure of respiratory muscles resulting from hypoperfusion in shock. This review points out that few studies have examined the clinical role of HFNO during shock-induced respiratory failure. One study found that HFNO significantly reduced respiratory effort, drive, and rate in septic and septic shock patients compared to COT. 

Use of high flow nasal oxygen during procedures 

The review concludes that preoxygenation with HFNO prior to intubation is likely to benefit some patient groups including neonates, patients with difficult airways and obese patients. HFNO prior to intubation is non-inferior to NIPPV for patients with obesity.  

Conclusion 

This extensive literature review supports HFNO as a valuable addition to the options for managing respiratory distress. Benefits of the modality include more portability as compared to NIPPV, allowing greater freedom of movement for the patient and the ability to eat and speak with healthcare providers and loved ones, and the ability to admit such patients to lower acuity areas of the hospital. The authors note that more high-quality studies are needed to evaluate clinical benefits in various patient populations.  

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