High-Flow Nasal Cannula: A Promising Oxygen Therapy for Patients with Severe Bronchial Asthma Complicated with Respiratory Failure

High-flow nasal oxygen therapy compared with conventional oxygen therapy in hospitalised patients with respiratory illness: a systematic review and meta-analysis

BACKGROUND

High-flow nasal oxygen therapy (HFNO) is used in diverse hospital settings to treat patients with acute respiratory failure (ARF). This systematic review aims to summarise the evidence regarding any benefits HFNO therapy has compared with conventional oxygen therapy (COT) for patients with ARF.

METHODS

Three databases (Embase, Medline and CENTRAL) were searched on 22 March 2023 for studies evaluating HFNO compared with COT for the treatment of ARF, with the primary outcome being hospital mortality and secondary outcomes including (but not limited to) escalation to invasive mechanical ventilation (IMV) or non-invasive ventilation (NIV). Risk of bias was assessed using the Cochrane risk-of-bias tool (randomised controlled trials (RCTs)), ROBINS-I (non-randomised trials) or Newcastle-Ottawa Scale (observational studies). RCTs and observational studies were pooled together for primary analyses, and secondary analyses used RCT data only. Treatment effects were pooled using the random effects model.

RESULTS

63 studies (26 RCTs, 13 cross-over and 24 observational studies) were included, with 10 230 participants. There was no significant difference in the primary outcome of hospital mortality (risk ratio, RR 1.08, 95% CI 0.93 to 1.26; p=0.29; 17 studies, n=5887) between HFNO and COT for all causes ARF. However, compared with COT, HFNO significantly reduced the overall need for escalation to IMV (RR 0.85, 95% CI 0.76 to 0.95 p=0.003; 39 studies, n=8932); and overall need for escalation to NIV (RR 0.70, 95% CI 0.50 to 0.98; p=0.04; 16 studies, n=3076). In subgroup analyses, when considering patients by illness types, those with acute-on-chronic respiratory failure who received HFNO compared with COT had a significant reduction in-hospital mortality (RR 0.58, 95% CI 0.37 to 0.91; p=0.02).

DISCUSSION

HFNO was superior to COT in reducing the need for escalation to both IMV and NIV but had no impact on the primary outcome of hospital mortality. These findings support recommendations that HFNO may be considered as first-line therapy for ARF.

PROSPERO REGISTRATION NUMBER

CRD42021264837.

The utility of the respiratory rate-oxygenation index as a predictor of treatment response in dogs receiving high-flow nasal cannula oxygen therapy

Objective

This study aims to evaluate the respiratory rate-oxygenation index (ROX) and the ratio of pulse oximetry saturation (SpO2) to the fraction of inspired oxygen (FiO2) (SpO2/FiO2, [SF]) to determine whether these indices are predictive of outcome in dogs receiving high-flow nasal cannula oxygen therapy (HFNOT).

Design

This is a prospective observational study.

Setting

This study was carried out at two university teaching hospitals.

Animals

In total, 88 dogs treated with HFNOT for hypoxemic respiratory failure due to various pulmonary diseases were selected.

Measurements and main results

The ROX index was defined as the SF divided by the respiratory rate (RR). ROX and SF were calculated at baseline and for each hour of HFNOT. The overall success rate of HFNOT was 38% (N = 33/88). Variables predicting HFNOT success were determined using logistic regression, and the predictive power of each variable was assessed using the area under the receiver operating curve (AUC). ROX and SF were adequately predictive of HFNOT success when averaged over 0-16 h of treatment, with similar AUCs of 0.72 (95% confidence interval [CI] 0.60-0.83) and 0.77 (95% CI 0.66-0.87), respectively (p < 0.05). SF showed acceptable discriminatory power in predicting HFNOT outcome at 7 h, with an AUC of 0.77 (95% CI 0.61-0.93, p = 0.013), and the optimal cutoff for predicting HFNC failure at 7 h was SF ≤ 191 (sensitivity 83% and specificity 76%).

Conclusion

These indices were easily obtained in dogs undergoing HFNOT. The results suggest that ROX and SF may have clinical utility in predicting the outcomes of dogs on HFNOT. Future studies are warranted to confirm these findings in a larger number of dogs in specific disease populations.

Performance Characterisation of the Airvo2TM Nebuliser Adapter in Combination with the Aerogen SoloTM Vibrating Mesh Nebuliser for in Line Aerosol Therapy during High Flow Nasal Oxygen Therapy

High flow oxygen (HFO) therapy is a well-established treatment in respiratory disease. Concurrent aerosol delivery can greatly expediate their recovery. The aim of this work was to complete a comprehensive characterisation of one such HFO therapy system, the Airvo2TM, used in combination with the Aerogen SoloTM vibrating mesh nebuliser. Representative adult, infant, and paediatric head models were connected to a breathing simulator via a collection filter placed at the level of the trachea. A tracheostomy interface and nasal cannulas were used to deliver the aerosol. Cannula size and gas flow rate were varied across the full operating range recommended by the manufacturer. The tracheal and emitted doses were quantified via UV-spectrophotometry. The aerosol droplet diameter at the exit of the nares and tracheal interface was measured via cascade impaction. High gas flow rates resulted in low emitted and tracheal doses (%). Nasal cannula size had no significant effect on the tracheal dose (%) available in infant and paediatric models. Higher gas flow rates resulted in smaller aerosol droplets at the exit of the nares and tracheostomy interface. Gas flow rate was found to be the primary parameter affecting aerosol delivery. Thus, gas flow rates should be kept low and where possible, delivered using larger nasal cannulas to maximise aerosol delivery.

Respiratory support in the emergency department a systematic review and meta-analysis

BACKGROUND

An estimated 20% of emergency department (ED) patients require respiratory support (RS). Evidence suggests that nasal high flow (NHF) reduces RS need.

AIMS

This review compared NHF to conventional oxygen therapy (COT) or noninvasive ventilation (NIV) in adult ED patients.

METHOD

The systematic review (SR) and meta-analysis (MA) methods reflect the Cochrane Collaboration methodology. Six databases were searched for randomized controlled trials (RCTs) comparing NHF to COT or NIV use in the ED. Three summary estimates were reported: (1) need to escalate care, (2) mortality, and (3) adverse events (AEs).

RESULTS

This SR and MA included 18 RCTs (n = 1874 participants). Two of the five MA conclusions were statistically significant. Compared with COT, NHF reduced the risk of escalation by 45% (RR 0.55; 95% CI [0.33, 0.92], p = .02, NNT = 32); however, no statistically significant differences in risk of mortality (RR 1.02; 95% CI [0.68, 1.54]; p = .91) and AE (RR 0.98; 95% CI [0.61, 1.59]; p = .94) outcomes were found. Compared with NIV, NHF increased the risk of escalation by 60% (RR 1.60; 95% CI [1.10, 2.33]; p = .01); mortality risk was not statistically significant (RR 1.23, 95% CI [0.78, 1.95]; p = .37).

LINKING EVIDENCE TO ACTION

Evidence-based decision-making regarding RS in the ED is challenging. ED clinicians have at times had to rely on non-ED evidence to support their practice. Compared with COT, NHF was seen to be superior and reduced the risk of escalation. Conversely, for this same outcome, NIV was superior to NHF. However, substantial clinical heterogeneity was seen in the NIV delivered. Research considering NHF versus NIV is needed. COVID-19 has exposed the research gaps and slowed the progress of ED research.

In-Line Aerosol Therapy via Nasal Cannula during Adult and Paediatric Normal, Obstructive, and Restrictive Breathing

High-flow nasal oxygen therapy is being increasingly adopted in intensive and home care settings. The concurrent delivery of aerosolised therapeutics allows for the targeted treatment of respiratory illnesses. This study examined in-line aerosol therapy via a nasal cannula to simulated adult and paediatric models with healthy, obstructive and restrictive lung types. The Aerogen Solo vibrating mesh nebuliser was used in combination with the InspiredTM O2FLO high-flow therapy system. Representative adult and paediatric head models were connected to a breathing simulator, which replicated several different states of lung health. The aerosol delivery was quantified at the tracheal level using UV-spectrophotometry. Testing was performed at a range of supplemental gas flow rates applicable to both models. Positive end-expiratory pressure was measured pre-, during and post-nebulisation. The increases in supplemental gas flow rates resulted in a decrease in aerosol delivery, irrespective of lung health. Large tidal volumes and extended inspiratory phases were associated with the greatest aerosol delivery. Gas flow to inspiratory flow ratios of 0.29-0.5 were found to be optimum for aerosol delivery. To enhance aerosol delivery to patients receiving high-flow nasal oxygen therapy, respiratory therapists should keep supplemental gas-flow rates below the inspiratory flow of the patient.

Effect of nasal high-flow oxygen humidification on patients after cardiac surgery

Background

Although high-flow humidified oxygen therapy (HFNC) has emerged as an important treatment for respiratory failure, few studies have reported on whether HFNC is appropriate for patients with hypoxemia after cardiac surgery, and the clinical efficacy of HFNC in patients undergoing cardiac surgery is unclear.

Objective

To investigate the clinical effect of HFNC after cardiac surgery.

Methods

Convenience sampling was used to select 76 patients who underwent invasive mechanical ventilation and oxygen therapy after valve replacement or coronary artery bypass grafting from July 2019 to June 2021. The patients were divided into the routine group and the HFNC group according to the oxygen therapy provided after the operation. The patients in the routine group (N = 38) were treated with oxygen inhalation by face mask after the operation, while those in the HFNC group (N = 38) were treated with HFNC via nasal cavity. The arterial partial pressure of oxygen (PaO2), the arterial partial pressure of carbon dioxide (PaCO2) and the oxygenation index (OI) were observed and compared between the two groups at 6 h, 12 h and 24 h after treatment. The sputum viscosity, incidence of second intubation and the intensive care unit (ICU) stay time were evaluated.

Results

The difference in PaCO2 between the two groups was statistically significant at 24 h after treatment (p < 0.05). The PaO2 in the HFNC group was significantly higher than in the routine group at 24 h after treatment, and the OI of the routine group was lower than in the HFNC group at 6 h, 12 h and 24 h after treatment (p < 0.05). The sputum viscosity in the HFNC group was better than in the routine group at 12 h and 24 h after treatment. The second intubation rate and ICU stay time in the HFNC group were lower than in the routine group (p < 0.05).

Conclusion

Compared with conventional mask oxygen inhalation, HFNC can effectively reduce sputum viscosity, improve oxygenation, reduce the incidence of repeated intubation and meet patients' comfort needs. It is an advantageous respiratory support strategy for patients after cardiac surgery compared with invasive mechanical ventilation to oxygen therapy and is beneficial to the recovery of cardiopulmonary function.

[Diagnosis and treatment of asthma: a guideline for respiratory specialists 2023 - published by the German Respiratory Society (DGP) e. V.]

The management of asthma has fundamentally changed during the past decades. The present guideline for the diagnosis and treatment of asthma was developed for respiratory specialists who need detailed and evidence-based information on the new diagnostic and therapeutic options in asthma. The guideline shows the new role of biomarkers, especially blood eosinophils and fractional exhaled NO (FeNO), in diagnostic algorithms of asthma. Of note, this guideline is the first worldwide to announce symptom prevention and asthma remission as the ultimate goals of asthma treatment, which can be achieved by using individually tailored, disease-modifying anti-asthmatic drugs such as inhaled steroids, allergen immunotherapy or biologics. In addition, the central role of the treatment of comorbidities is emphasized. Finally, the document addresses several challenges in asthma management, including asthma treatment during pregnancy, treatment of severe asthma or the diagnosis and treatment of work-related asthma.

Noninvasive positive-pressure ventilation for children with acute asthma: a meta-analysis of randomized controlled trials

Background

Noninvasive positive-pressure ventilation (NPPV) can be effective in children with acute asthma. However, clinical evidence remains limited. The objective of the meta-analysis was to systematically assess NPPV's effectiveness and safety in treating children with acute asthma.

Methods

Relevant randomized controlled trials were obtained from electronic resources, including PubMed, Embase, Cochrane's Library, Wanfang, and CNKI databases. The influence of potential heterogeneity was taken into account before using a random-effect model to pool the results.

Results

A total of 10 RCTs involving 558 children with acute asthma were included in the meta-analysis. Compared to conventional treatment alone, additional use of NPPV significantly improved early blood gas parameters such as the oxygen saturation (mean difference [MD]: 4.28%, 95% confidence interval [CI]: 1.51 to 7.04, p = 0.002; I² = 80%), partial pressure of oxygen (MD: 10.61 mmHg, 95% CI: 6.06 to 15.16, p < 0.001; I² = 89%), and partial pressure of carbon dioxide (MD: -6.29 mmHg, 95% CI: -9.81 to -2.77, p < 0.001; I² = 85%) in the arterial blood. Moreover, NPPV was also associated with early reduced respiratory rate (MD: -12.90, 95% CI: -22.21 to -3.60, p = 0.007; I²= 71%), improved symptom score (SMD: -1.85, 95% CI: -3.65 to -0.07, p = 0.04; I² = 92%), and shortened hospital stay (MD: -1.82 days, 95% CI: -2.32 to -1.31, p < 0.001; I²= 0%). No severe adverse events related to NPPV were reported.

Conclusions

NPPV in children with acute asthma is associated with improved gas exchange, decreased respiratory rates, a lower symptom score, and a shorter hospital stay. These results suggest that NPPV may be as effective and safe as conventional treatment for pediatric patients with acute asthma.

The efficacy of high-flow oxygen versus conventional oxygen for asthma control: a meta-analysis of randomized controlled studies

Introduction

The efficacy of high-flow oxygen versus conventional oxygen therapy for asthma control remains controversial.

Aim

This meta-analysis aims to explore the influence of high-flow oxygen versus conventional oxygen therapy on asthma control.

Material and methods

We have searched PubMed, Embase, Web of Science, EBSCO, and Cochrane library databases, and included randomized controlled trials (RCTs) assessing the efficacy of high-flow oxygen versus conventional oxygen therapy for asthma control.

Results

Four RCTs are included in this meta-analysis. Overall, compared with conventional oxygen therapy for asthma, high-flow oxygen is associated with a significantly lower dyspnoea score (standard mean difference (SMD) = -0.63; 95% confidence interval (CI): -1.08 to -0.17; p = 0.008), but reveals no remarkable influence on PaCO₂ (SMD = 0.28; 95% CI: -0.22 to 0.77; p = 0.28), PaO₂ (SMD = 0.44; 95% CI: -1.34 to 2.22; p = 0.63), intubation rate (OR = 1.09; 95% CI: 0.15 to 8.21; p = 0.93) or hospital length of stay (SMD = -0.07; 95% CI: -0.41 to 0.27; p = 0.67).

Conclusions

High-flow oxygen may benefit to reduce/may be more beneficial in reducing the dyspnoea score than conventional oxygen therapy for asthma, but shows no improvement in PaCO₂, PaO₂, intubation or hospital length of stay.

High-flow nasal oxygen in acute hypoxemic respiratory failure: A narrative review of the evidence before and after the COVID-19 pandemic

High-flow nasal oxygen (HFNO) is a type of non-invasive advanced respiratory support that allows the delivery of high-flow and humidified air through a nasal cannula. It can deliver a higher inspired oxygen fraction than conventional oxygen therapy (COT), improves secretion clearance, has a small positive end-expiratory pressure, and exhibits a washout effect on the upper air space that diminishes dead space ventilation. HFNO has been shown to reduce the work of breathing in acute hypoxemic respiratory failure (AHRF) and has become an interesting option for non-invasive respiratory support. Evidence published before the COVID-19 pandemic suggested a possible reduction of the need for invasive mechanical ventilation compared to COT. The COVID-19 pandemic has resulted in a substantial increase in AHRF worldwide, overwhelming both acute and intensive care unit capacity in most countries. This triggered new trials, adding to the body of evidence on HFNO in AHRF and its possible benefits compared to COT or non-invasive ventilation. We have summarized and discussed this recent evidence to inform the best supportive strategy in AHRF both related and unrelated to COVID-19.

ERS Clinical Practice Guidelines: High-flow nasal cannula in acute respiratory failure

BACKGROUND

High-flow nasal cannula (HFNC) has become a frequently used non-invasive form of respiratory support in acute settings, however evidence supporting its use has only recently emerged. These guidelines provide evidence-based recommendations for the use of HFNC alongside other noninvasive forms of respiratory support in adults with acute respiratory failure (ARF).

MATERIALS AND METHODOLOGY

The European Respiratory Society Task Force panel included expert clinicians and methodologists in pulmonology and intensive care medicine. The Task Force used the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) methods to summarize evidence and develop clinical recommendations for the use of HFNC alongside conventional oxygen therapy (COT) and non-invasive ventilation (NIV) for the management of adults in acute settings with ARF.

RESULTS

The Task Force developed 8 conditional recommendations, suggesting using: 1) HFNC over COT in hypoxemic ARF, 2) HFNC over NIV in hypoxemic ARF, 3)HFNC over COT during breaks from NIV, 4) either HFNC or COT in post-operative patients at low risk of pulmonary complications, 5) either HFNC or NIV in post-operative patients at high risk of pulmonary complications, 6) HFNC over COT in non-surgical patients at low risk of extubation failure, 7) NIV over HFNC for patients at high risk of extubation failure unless there are relative or absolute contraindications to NIV, 8) trialling NIV prior to use of HFNC in patients with chronic obstructive pulmonary disease (COPD) and hypercapnic ARF.

CONCLUSIONS

HFNC is a valuable intervention in adults with ARF. These conditional recommendations can assist clinicians in choosing the most appropriate form of non-invasive respiratory support to provide to patients in different acute settings.

Bronchodilator Delivery via High-Flow Nasal Cannula: A Randomized Controlled Trial to Compare the Effects of Gas Flows

(1) Background: Aerosol delivery via high-flow nasal cannula (HFNC) has attracted increasing clinical interest. In vitro studies report that the ratio of HFNC gas flow to patient inspiratory flow (GF:IF) is a key factor in the efficiency of trans-nasal aerosol delivery. (2) Methods: In a randomized controlled trial, patients with a history of COPD or asthma and documented positive responses to inhaled bronchodilators in an outpatient pulmonary function laboratory were recruited. Subjects were randomized to receive inhalation at gas flow ratio settings of: GF:IF = 0.5, GF:IF = 1.0, or GF = 50 L/min. Subjects were assigned to inhale saline (control) followed by salbutamol via HFNC with cumulative doses of 0.5 mg, 1.5 mg, 3.5 mg, and 7.5 mg. Spirometry was performed at baseline and 10-12 min after each inhalation. (3) Results: 75 subjects (49 asthma and 26 COPD) demonstrating bronchodilator response were enrolled. Per the robust ATS/ERS criteria no difference was observed between flows, however using the criteria of post-bronchodilator forced expiratory volume in the first second (FEV₁) reaching the screening post-bronchodilator FEV₁ with salbutamol, a higher percentage of subjects receiving GF:IF = 0.5 met the criteria at a cumulative dose of 1.5 mg than those receiving GF:IF = 1.0, and GF = 50 L/min (64% vs. 29% vs. 27%, respectively, p = 0.011). Similarly at 3.5 mg (88% vs. 54% vs. 46%, respectively, p = 0.005). The effective dose at GF:IF = 0.5 was 1.5 mg while for GF = 50 L/min it was 3.5 mg. (4) Conclusions: During salbutamol delivery via HFNC, cumulative doses of 1.5 mg to 3.5 mg resulted in effective bronchodilation. Applying the robust ATS/ERS criteria no difference was observed between the flows, however using the more sensitive criteria of subjects reaching post screening FEV₁ to salbutamol via HFNC, a higher number of subjects responded to the doses of 0.5 mg and 1.5 mg when HFNC gas flow was set at 50% of patient peak inspiratory flow.

High-Flow Nasal Cannula in Pediatric Critical Asthma

BACKGROUND

High-flow nasal cannula (HFNC) has been used in the treatment of pediatric asthma, although high-quality data comparing HFNC to aerosol mask nebulizer are lacking. We hypothesized that HFNC would perform similarly to the aerosol mask for meaningful clinical outcomes in children with critical asthma.

METHODS

We retrospectively reviewed the medical records of children with critical asthma (age 2-17 y) with a modified pulmonary index score (MPIS) ≥ 8 admitted to our pediatric ICU as part of a quality improvement project. Patients were managed with our MPIS-based, respiratory therapist-driven protocol. Subjects were divided into 2 cohorts by initial respiratory support: HFNC or aerosol mask. Data included demographics, initial respiratory support, and MPIS over time. Primary outcome was hospital length of stay (LOS). Secondary outcome was difference in MPIS over time.

RESULTS

We included 171 subjects, with 104 in the HFNC group and 67 in the aerosol mask group. Median (interquartile range [IQR]) age was lower in the HFNC group (5 [IQR 4-9] vs 7 [IQR 5-10] y, P = .006)], while other demographic characteristics were similar. Initial MPIS was similar between HFNC and aerosol mask groups (11 [IQR 9-12] vs 10 [IQR 9-12], P = .15). There were no significant differences for hospital LOS (2.9 [IQR 2.1-3.9] vs 3.0 [IQR 2.3-4.4] d, P = .47), pediatric ICU LOS (1.9 [IQR 1.4-2.8] vs 1.8 [IQR 1.5-3.0] d, P = .92), or time to MPIS < 6 (1.0 [IQR 0.6-1.6] vs 1.3 [IQR 0.8-1.9) d, P = .09) between the HFNC and aerosol mask groups, respectively. Median time on continuous albuterol was shorter in the HFNC group compared to the aerosol mask group (1.0 [IQR 0.7-1.8] vs 1.5 [IQR 0.9-2.3] d, P = .048). Of note, 16 (24%) subjects in the aerosol mask group were eventually treated with HFNC. Use of a helium-oxygen mixture and noninvasive ventilation was similar between groups.

CONCLUSIONS

HFNC performed similarly to aerosol mask in pediatric patients with critical asthma.

Effectiveness and Harms of High-Flow Nasal Oxygen for Acute Respiratory Failure: An Evidence Report for a Clinical Guideline From the American College of Physicians

BACKGROUND

Use of high-flow nasal oxygen (HFNO) for treatment of adults with acute respiratory failure (ARF) has increased.

PURPOSE

To assess HFNO versus noninvasive ventilation (NIV) or conventional oxygen therapy (COT) for ARF in hospitalized adults.

DATA SOURCES

English-language searches of MEDLINE, Embase, CINAHL, and Cochrane Library from January 2000 to July 2020; systematic review reference lists.

STUDY SELECTION

29 randomized controlled trials evaluated HFNO versus NIV (k = 11) or COT (k = 21).

DATA EXTRACTION

Data extraction by a single investigator was verified by a second, 2 investigators assessed risk of bias, and evidence certainty was determined by consensus.

DATA SYNTHESIS

Results are reported separately for HFNO versus NIV, for HFNO versus COT, and by initial or postextubation management. Compared with NIV, HFNO may reduce all-cause mortality, intubation, and hospital-acquired pneumonia and improve patient comfort in initial ARF management (low-certainty evidence) but not in postextubation management. Compared with COT, HFNO may reduce reintubation and improve patient comfort in postextubation ARF management (low-certainty evidence).

LIMITATIONS

Trials varied in populations enrolled, ARF causes, and treatment protocols. Trial design, sample size, duration of treatment and follow-up, and results reporting were often insufficient to adequately assess many outcomes. Protocols, clinician and health system training, cost, and resource use were poorly characterized.

CONCLUSION

Compared with NIV, HFNO as initial ARF management may improve several clinical outcomes. Compared with COT, HFNO as postextubation management may reduce reintubations and improve patient comfort; HFNO resulted in fewer harms than NIV or COT. Broad applicability, including required clinician and health system experience and resource use, is not well known.

PRIMARY FUNDING SOURCE

American College of Physicians. (PROSPERO: CRD42019146691).

The effect of high flow nasal oxygen therapy in intensive care units: a systematic review and meta-analysis

BACKGROUND

High flow nasal oxygen (HFNO) therapy has been widely used in intensive care units (ICU); however, its efficacy remains inconclusive. This systematic review and meta-analysis aimed to compare the efficacy of HFNO therapy with th at of alternative noninvasive oxygen therapies such as conventional oxygen therapy (COT) and noninvasive ventilation (NIV) in ICU.

METHODS

A Pubmed, Embase, Web of Science, Cochrane Library database search was performed in March 2020. Results: The meta-analysis ultimately included 17 clinical studies. Compared with the overall effect of COT and NIV, HFNO was associated with a low incidence of pneumonia (95% CI: 0.6-0.99, P = 0.04) and improvement in lowest pulse oxygen saturation (SpO₂) during oxygenation (95% CI: 0.02-1.61; P = 0.04). However, no differences were detected in the following outcomes: length of ICU stay, the rate of intubation or reintubation, mortality at day 28, hospital mortality, and SpO₂ at the end of oxygen therapy (all P > 0.05).

CONCLUSIONS

In adult patients in ICU, HFNO may improve oxygenation and decrease pneumonia rate without affecting the length of ICU stay, intubation or reintubation rate, mortality, and SpO₂ at the end of oxygen therapy.

Nasal High-flow Oxygen Versus Conventional Oxygen Therapy for Acute Severe Asthma Patients: A Pilot Randomized Controlled Trial

Background

Nasal high flow (NHF) has demonstrated efficacy in relieving dyspnea in various patients with hypoxemic and hypercapnic respiratory failure. It may also reduce dyspnea in patients with acute severe asthma in the emergency department (ED). The aim of the study was to compare the efficacy of NHF with conventional oxygen therapy (COT) in improving dyspnea in acute severe asthma patients with hypoxemia in the ED.

Methods

This pilot nonblinded randomized controlled trial was conducted involving 37 patients aged ≥ 18 years with acute severe asthma and hypoxemia in the ED of Siriraj Hospital, Bangkok, Thailand (TCTR20180926003). The participants were randomly allocated to receive either COT (n = 18) or NHF (n = 19) for 120 minutes. The primary outcome was comparing the intervention effects on the patients’ degree of dyspnea measured using the modified Borg scale (MBS). The secondary outcomes were comparing the interventions based on the numeric rating scale (NRS) of dyspnea, the dyspnea scale assessing accessory muscle use, vital signs, and blood gas results.

Results

The intention‐to‐treat analysis included 37 patients (COT group n = 18 and NHF group n = 19). The baseline mean MBS was 7.8 in both groups. At 120 minutes, the mean (±SD) MBSs in patients receiving COT and NHF were 3.3 (±2.5) and 1.4 (±2.5), respectively (mean difference = 1.9 [95% CI = 0.2 to 3.8], p = 0.043). The trends in NRS and dyspnea score results were similar to those of MBS. Respiratory rates were lower with NHF (mean difference = 4.7 [95% CI = 1.5 to 7.8], p = 0.001). No between‐ or within‐group differences in blood gas results were found.

Conclusion

Nasal high flow reduced the severity of dyspnea and respiratory rate in hypoxemic patients with acute severe asthma in the ED.

High-flow nasal cannula and bilevel positive airway pressure for pediatric status asthmaticus: a single center, retrospective descriptive and comparative cohort study

INTRODUCTION

We aimed to describe patient characteristics and clinical outcomes for children hospitalized for status asthmaticus (SA) receiving high-flow nasal cannula (HFNC) or bilevel positive airway pressure (BiPAP).

METHODS

We performed a single center, retrospective cohort study among 39 children admitted for SA aged 5-17 years from January 2016 to May 2019 to a quaternary pediatric intensive care unit (PICU). Cohorts were defined by BiPAP versus HFNC exposure and assessed to determine if differences existed in demographics, anthropometrics, comorbidities, asthma severity indices, historical factors, duration of noninvasive ventilation, and asthma-related clinical outcomes (i.e. length of stay, mechanical ventilation rates, exposure to concurrent sedatives/anxiolysis, and rate of adjunctive therapy exposure).

RESULTS

Thirty-three percent (n = 13) received HFNC (33%) and 67% (n = 26) BiPAP. Children receiving BiPAP had greater age (10.9 ± 3.7 vs. 6.8 ± 2.2 years, P < 0.01), asthma severity (proportion with severe NHLBI classification: 38% vs. 0%, P < 0.01; median pediatric asthma severity score: 13[12,14] vs. 10[9,12], P < 0.01), previous PICU admissions (62% vs. 15%, P = 0.01), frequency of prescribed anxiolysis/sedation (42% vs. 8%, P = 0.02), and median duration of continuous albuterol (1.7[1,3.1] vs. 0.9[0.7,1.6] days, P = 0.03) compared to those on HFNC. Those on HFNC more commonly were treated comorbid bacterial pneumonia (69% vs. 19%, P < 0.01). No differences in NIV duration, mortality, mechanical ventilation rates, or LOS were observed.

CONCLUSIONS

Our data suggest a trial of BiPAP or HFNC appears well tolerated in children with SA. Prospective trials are needed to establish modality superiority and identify patient or clinical characteristics that prompt use of HFNC over BiPAP.

High flow nasal cannula in asthmatic children with suspected COVID-19

Abstract Introduction: The use of a high-flow nasal cannula as an alternative treatment for acute respiratory failure can reduce the need for invasive mechanical ventilation and the duration of hospital stays. Objective: The present study aimed to describe the use of a high-flow nasal cannula in pediatric asthmatic patients with acute respiratory failure and suspected COVID-19. Methods: To carry out this research, data were collected from medical records, including three patients with asthma diagnoses. The variables studied were: personal data (name, age in months, sex, weight, and color), clinical data (physical examination, PRAM score, respiratory rate, heart rate, and peripheral oxygen saturation), diagnosis, history of the current disease, chest, and laboratory radiography (arterial blood gases and reverse-transcriptase polymerase chain reaction). Clinical data were compared before and after using a high-flow nasal cannula. Results: After the application of the therapy, a gradual improvement in heart, respiratory rate, PaO2/FiO2 ratio, and the Pediatric Respiratory Assessment Measure score was observed. Conclusion: The simple and quick use of a high-flow nasal cannula in pediatric patients with asthma can be safe and efficient in improving their respiratory condition and reducing the need for intubation.

High-flow nasal cannula for acute hypoxemic respiratory failure in patients with COVID-19: systematic reviews of effectiveness and its risks of aerosolization, dispersion, and infection transmission

PURPOSE

We conducted two World Health Organization-commissioned reviews to inform use of high-flow nasal cannula (HFNC) in patients with coronavirus disease (COVID-19). We synthesized the evidence regarding efficacy and safety (review 1), as well as risks of droplet dispersion, aerosol generation, and associated transmission (review 2) of viral products.

SOURCE

Literature searches were performed in Ovid MEDLINE, Embase, Web of Science, Chinese databases, and medRxiv. Review 1: we synthesized results from randomized-controlled trials (RCTs) comparing HFNC to conventional oxygen therapy (COT) in critically ill patients with acute hypoxemic respiratory failure. Review 2: we narratively summarized findings from studies evaluating droplet dispersion, aerosol generation, or infection transmission associated with HFNC. For both reviews, paired reviewers independently conducted screening, data extraction, and risk of bias assessment. We evaluated certainty of evidence using GRADE methodology.

PRINCIPAL FINDINGS

No eligible studies included COVID-19 patients. Review 1: 12 RCTs (n = 1,989 patients) provided low-certainty evidence that HFNC may reduce invasive ventilation (relative risk [RR], 0.85; 95% confidence interval [CI], 0.74 to 0.99) and escalation of oxygen therapy (RR, 0.71; 95% CI, 0.51 to 0.98) in patients with respiratory failure. Results provided no support for differences in mortality (moderate certainty), or in-hospital or intensive care length of stay (moderate and low certainty, respectively). Review 2: four studies evaluating droplet dispersion and three evaluating aerosol generation and dispersion provided very low certainty evidence. Two simulation studies and a crossover study showed mixed findings regarding the effect of HFNC on droplet dispersion. Although two simulation studies reported no associated increase in aerosol dispersion, one reported that higher flow rates were associated with increased regions of aerosol density.

CONCLUSIONS

High-flow nasal cannula may reduce the need for invasive ventilation and escalation of therapy compared with COT in COVID-19 patients with acute hypoxemic respiratory failure. This benefit must be balanced against the unknown risk of airborne transmission.