Nasal High-flow versus non-invasive ventilation in stable hypercapnic COPD: a preliminary report

Effectiveness, Adherence and Safety of Home High Flow Nasal Cannula in Chronic Respiratory Disease and Respiratory Insufficiency: A Systematic Review

INTRODUCTION

The effectiveness of home high flow nasal cannula (HFNC) for the treatment of chronic respiratory failure in patients with chronic respiratory diseases (CRDs) has not been summarized. We aimed to conduct a systematic review of the effectiveness, adherence, and safety of HFNC in the long-term treatment of patients with chronic respiratory diseases and respiratory failure.

METHODS

A systematic review was conducted. PubMed, Web of science, and SCOPUS were search up to August 2023. Long-term HFNC studies (≥4 weeks) reporting dyspnea; exacerbations, hospitalizations; peripheral oxygen saturation (SpO2), comfort; patient experience, health-related quality of life or partial pressure of carbon dioxide (paCO2) were included.

RESULTS

Thirteen articles (701 patients) based on 10 studies were selected: randomized control trials (n=3), randomized crossover trials (n=2), crossover (n=3) and retrospective (n=2) studies. COPD (n=6), bronchiectasis (n=2), COPD/bronchiectasis (n=1) and ILD (n=1) were the underlined CRDs. HFNC reduced exacerbations when compared to usual care/home respiratory therapies (n=6). Quality of life outcomes were also in favor of HFNC in patients with COPD and bronchiectasis (n=6). HFNC had significant effects on hospitalizations, paCO2, and lung function. Adherence ranged from 5.2 to 8.6h/day (n=5). Three studies reported no events, 3 non-serious events and 2 no differences compared with other home respiratory therapies.

CONCLUSIONS

HFNC seems more effective than usual care or other home respiratory therapies in reducing exacerbations and improving quality of life in patients with COPD and bronchiectasis, while presenting good adherence and being safe. Its apparently superior effectiveness needs to be better studied in future real-world pragmatic trials.

A Real-Life Study of Combined Treatment with Long-Term Non-Invasive Ventilation and High Flow Nasal Cannula in Patients with End-Stage Chronic Obstructive Lung Disease

Patients with end-stage chronic obstructive pulmonary disease (COPD) often develop persistent hypoxic or hypercapnic respiratory failure, or a combination of both. Ventilatory support, in terms of a long-term high-flow nasal cannula (LT-HFNC) and long-term non-invasive ventilation (LT-NIV), may be indicated. Often, clinicians choose either one or the other. This paper explores combined treatment with LT-HFNC and LT-NIV in a real-life setting. In total, 33 patients with COPD and persistent respiratory failure were included in this study. Of those, 17 were initiated on LT-HFNC and used it for 595 (374) days and 16 were initiated on LT-NIV and used it for 558 (479) days. On average, patients used respiratory support continuously for 908 (586) days. Baseline characteristics were comparable, apart from PaCO₂ at first ventilatory support initiation (LT-HFNC/LT-NIV 7.1 (1.1) kPa/8.8 (0.9) kPa respectively (p = 0.002)). Both groups experienced a reduction in hospitalizations in the first twelve months after treatment initiation, compared to the twelve months before (LT-HFNC p = 0.022 and LT-NIV p = 0.014). In total, 25% of LT-NIV patients stopped treatment after HFNC initiation due to intolerance and 59% stopped LT-HFNC treatment 126 (36) days after LT-NIV initiation as monotherapy was sufficient. In 44% of these patients, LT-HFNC was re-initiated at the end of life. At the time of analysis, 70% of patients had died. In the last three months of life, patients stopped using LT-NIV, whereas 91% used LT-HFNC. In conclusion, the combined use of LT-NIV and LT-HFNC reduced hospitalizations in patients with COPD and persistent respiratory failure. The study indicates that LT-HFNC is well tolerated, and better tolerated than LT-NIV at the very end stages of COPD.

High-Flow Nasal Oxygen versus Noninvasive Ventilation in Acute Exacerbation of Chronic Obstructive Pulmonary Disease Patients: A Meta-Analysis of Randomized Controlled Trials

Background

High-flow nasal cannula (HFNC) can be used in stable chronic obstructive pulmonary disease (COPD) patients, but the effect of HFNC on clinical outcomes in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) is still uncertain.

Methods

We searched electronic literature databases for randomized controlled trials (RCTs) comparing HFNC with noninvasive ventilation (NIV) in hypercapnic patients with AECOPD. The primary endpoint of this meta-analysis was PaCO₂, PaO_2, and SpO₂. The secondary outcomes were the respiratory rate, mortality, complications, and intubation rate.

Results

We included 7 RCTs with a total of 481 patients. There were no significant differences on measures of PaCO₂ (MD = -0.42, 95%CI -3.60 to 2.75, Z = 0.26, and P = 0.79), PaO₂ (MD = -1.36, 95%CI -4.69 to 1.97, Z = 0.80, and P = 0.42), and SpO₂ (MD = -0.78, 95%CI -1.67 to 0.11, Z = 1.72, P = 0.08) between the HFNC group and the NIV group. There was no significant difference in measures of the mortality and intubation rate between the HFNC group (OR = 0.72, 95%CI 0.30 to 1.69, Z = 0.76, and P = 0.44) and the NIV group (OR = 2.38, 95%CI 0.49 to 11.50, Z = 1.08, and P = 0.28), respectively. But the respiratory rate in the HFNC group was lower than that in the NIV group (MD = -1.13, 95%CI -2.13 to -0.14, Z = 2.23, and P = 0.03), and fewer complications were found in the HFNC group (OR = 0.26, 95%CI 0.14 to 0.47, Z = 4.46, and P < 0.00001).

Conclusion

NIV was noninferior to HFNC in decreasing PaCO₂ and increasing PaO₂ and SpO₂. Similarly, the mortality and intubation rate was similar among the two groups. The respiratory rate and complications were inferior in the AECOPD group treated with HFNC.

Home High-Flow Nasal Cannula Oxygen Therapy for Stable Hypercapnic COPD: A Randomized Clinical Trial

Rationale: The long-term effects of using a high-flow nasal cannula for chronic hypercapnic respiratory failure caused by chronic obstructive pulmonary disease remain unclear. Objectives: To assess whether long-term high-flow nasal cannula use reduces the number of exacerbations and improves other physiological parameters in patients with chronic hypercapnic respiratory failure caused by chronic obstructive pulmonary disease. Methods: We enrolled 104 participants (aged ⩾40 yr) with daytime hypercapnia (Global Initiative for Chronic Obstructive Lung Disease stages 2-4) receiving long-term oxygen therapy (⩾16 h/d for ⩾1 mo) and randomly assigned them to high-flow nasal cannula/long-term oxygen therapy and long-term oxygen therapy groups. The primary endpoint was the moderate or severe exacerbation rate. We compared changes from baseline in arterial blood gas values, peripheral oxygen saturation, pulmonary function, health-related quality-of-life scores, and the 6-minute-walk test. Measurements and Main Results: High-flow nasal cannula use significantly reduced the rate of moderate/severe exacerbations (unadjusted mean count 1.0 vs. 2.5, a ratio of the adjusted mean count between groups [95% confidence interval] of 2.85 [1.48-5.47]) and prolonged the duration without moderate or severe exacerbations. The median time to first moderate or severe exacerbation in the long-term oxygen therapy group was 25 (14.1-47.4) weeks; this was not reached in the high-flow nasal cannula/long-term oxygen therapy group. High-flow nasal cannula use significantly improved health-related quality of life scores, peripheral oxygen saturation, and specific pulmonary function parameters. No safety concerns were identified. Conclusions: A high-flow nasal cannula is a reasonable therapeutic option for patients with stable hypercapnic chronic obstructive pulmonary disease and a history of exacerbations. Clinical trial registered with www.umin/ac.jp (UMIN000028581) and www.clinicaltrials.gov (NCT03282019).

Epidermal growth factor receptor mutation‐positive advanced lung adenocarcinoma presenting with acute respiratory failure diagnosed by thin bronchoscope through transnasal route under high‐concentration oxygen mask

A 59‐year‐old woman complained of continuous dyspnea. Computed tomography revealed multiple pulmonary nodules, mildly small enlarged mediastinal lymph nodes and a nodule in the liver segment 8. Her dyspnea worsened with respiratory failure 4 days after presentation. Liver biopsy was not possible as she could not hold her breath; thus, we performed bronchoscopy. For biopsy, the pulmonary nodules with a positive bronchus sign were preferred over the mildly small enlarged mediastinal lymph nodes. Bronchoscopy under non‐invasive positive pressure ventilation (NPPV) or high‐flow nasal cannula (HFNC) was impossible because of the lack of equipment. Therefore, we biopsied via thin bronchoscope through nasal cavity under a high‐concentration oxygen mask. Pathological findings revealed epidermal growth factor receptor mutation‐positive lung adenocarcinoma. For patients with respiratory failure who cannot undergo bronchoscopy under NPPV or HFNC, thin bronchoscopy through the nasal cavity under a high‐concentration oxygen mask may be clinically useful to prevent hypoxaemia during the procedure

Noninvasive Oxygenation in Patients with Acute Respiratory Failure: Current Perspectives

Purpose of Review

High-flow nasal oxygen and noninvasive ventilation are two alternative strategies to standard oxygen in the management of acute respiratory failure.

Discussion

Although high-flow nasal oxygen has gained major popularity in ICUs due to its simplicity of application, good comfort for patients, efficiency in improving oxygenation and promising results in patients with acute hypoxemic respiratory failure, further large clinical trials are needed to confirm its superiority over standard oxygen. Non-invasive ventilation may have deleterious effects, especially in patients exerting strong inspiratory efforts, and no current recommendations support its use in this setting. Protective non-invasive ventilation using higher levels of positive-end expiratory pressure, more prolonged sessions and other interfaces such as the helmet may have beneficial physiological effects leading to it being proposed as alternative to high-flow nasal oxygen in acute hypoxemic respiratory failure. By contrast, non-invasive ventilation is the first-line strategy of oxygenation in patients with acute exacerbation of chronic lung disease, while high-flow nasal oxygen could be an alternative to non-invasive ventilation after partial reversal of respiratory acidosis. Questions remain about the target populations and non-invasive oxygen strategy representing the best alternative to standard oxygen in acute hypoxemic respiratory failure. As concerns acute on-chronic-respiratory failure, the place of high-flow nasal oxygen remains to be evaluated.

Current Practice of High Flow through Nasal Cannula in Exacerbated COPD Patients

Acute Exacerbation of Chronic Obstructive Pulmonary Disease is a form of severe Acute Respiratory Failure (ARF) requiring Conventional Oxygen Therapy (COT) in the case of absence of acidosis or the application of Non-Invasive Ventilation (NIV) in case of respiratory acidosis. In the last decade, High Flow through Nasal Cannula (HFNC) has been increasingly used, mainly in patients with hypoxemic ARF. However, some studies were also published in AECOPD patients, and some evidence emerged. In this review, after describing the mechanism underlying potential clinical benefits, we analyzed the possible clinical application of HFNC to AECOPD patients. In the case of respiratory acidosis, the gold-standard treatment remains NIV, supported by strong evidence in favor. However, HFNC may be considered as an alternative to NIV if the latter fails for intolerance. HFNC should also be considered and preferred to COT at NIV breaks and weaning. Finally, HFNC should also be preferred to COT as first-line oxygen treatment in AECOPD patients without respiratory acidosis.

Nasal high-flow compared to non-invasive ventilation in treatment of acute acidotic hypercapnic exacerbation of chronic obstructive pulmonary disease-protocol for a randomized controlled noninferiority trial (ELVIS)

Background

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) have a major negative impact on health status, rates of hospitalization, readmission, disease progression and mortality. Non-invasive ventilation (NIV) is the standard therapy for hypercapnic acidotic respiratory failure in AECOPD. Despite its beneficial effects, NIV is often poorly tolerated (11–34 % failure rate). An increasing number of studies have documented a beneficial effect of nasal high-flow (NHF) in acute hypercapnia. We designed a prospective, randomized, multi-centre, open label, non-inferiority trial to compare treatment failure in nasal NHF vs NIV in patients with acidotic hypercapnic AECOPD.

Methods

The study will be conducted in about 35 sites in Germany. Patients with hypercapnic AECOPD with respiratory acidosis (pH < 7.35) will be randomized 1:1 to NIV or NHF. The primary outcome is the combined endpoint of intubation, treatment failure or death at 72 h. The switch from one to the other device marks a device failure but acts as a rescue treatment in absence of intubation criteria. A sample size of 720 was calculated to have 80% power for showing that NHF is non-inferior to NIV with a margin of 8 percentage points. Linear regression will be used for the confirmatory analysis.

Discussion

If NHF is shown to be non-inferior to NIV in acidotic hypercapnic AECOPD, it could become an important alternative treatment.

Trial registration

ClinicalTrials.gov, NCT04881409, Registered on May 11, 2021

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05978-z.

β Agonist Delivery by High-Flow Nasal Cannula During COPD Exacerbation: A Prospective Physiological Study

BACKGROUND

Whereas high-flow nasal cannula (HFNC) oxygen therapy is increasingly used in patients with exacerbation of COPD, the effectiveness of β ₂ agonist nebulization through HFNC has been poorly assessed. We hypothesized that salbutamol vibrating-mesh nebulization through HFNC improves pulmonary function tests in subjects with COPD.

METHODS

We conducted a physiological crossover study including subjects admitted to the ICU for severe exacerbation of COPD. After subject improvement allowing a 3-h washout period without bronchodilator, pulmonary function tests were performed while breathing through HFNC alone and after salbutamol vibrating-mesh nebulization through HFNC. The primary end point consisted in the changes in FEV₁ before and after salbutamol nebulization. Secondary end points included the changes in FVC, peak expiratory flow (PEF), airway resistance, and clinical parameters.

RESULTS

Among the 15 subjects included, mean (SD) FEV₁ significantly increased after salbutamol nebulization from 931 mL (383) to 1,019 (432), mean difference +87 mL (95% CI 30-145) (P = .006). Similarly, FVC and PEF significantly increased, +174 mL (95% CI 66-282) (P = .004) and +0.3 L/min (95% CI 0-0.6) (P = .037), respectively. Airway resistances and breathing frequency did not significantly differ, whereas heart rate significantly increased after nebulization.

CONCLUSIONS

In subjects with severe exacerbation of COPD, salbutamol vibrating-mesh nebulization through HFNC induced a significant bronchodilator effect with volume and flow improvement.

Cost-Effectiveness of Domiciliary High Flow Nasal Cannula Treatment in COPD Patients with Chronic Respiratory Failure

PURPOSE

To evaluate the cost-effectiveness of long-term domiciliary high flow nasal cannula (HFNC) treatment in COPD patients with chronic respiratory failure.

PATIENTS AND METHODS

A cohort of 200 COPD patients were equally randomized into usual care ± HFNC and followed for 12 months. The outcome of the analysis was the incremental cost per quality-adjusted life-year (QALY) gained, and the analysis was conducted from a healthcare sector perspective. Data on the patients' health-related quality of life (HRQoL), gathered throughout the trial using the St. George's Respiratory Questionnaire (SGRQ), was converted into EQ-5D-3L health state utility values. Costs were estimated using Danish registers and valued in British pounds (£) at price level 2019. Scenario analyses and probabilistic sensitivity analyses were conducted to assess the uncertainty of the results.

RESULTS

The adjusted mean difference in QALYs between the HFNC group and the control group was 0.059 (95% CI: 0.017; 0.101), and the adjusted mean difference in total costs was £212 (95% CI: -1572; 1995). The analysis resulted in an incremental cost-effectiveness ratio (ICER) of £3605 per QALY gained. At threshold values of £20.000-30.000 per QALY gained, the intervention had an 83-92% probability of being cost-effective. The scenario analyses all revealed ICERs below the set threshold value and demonstrated the robustness of the main result.

CONCLUSION

This is the first cost-effectiveness study on domiciliary HFNC in Europe. The findings demonstrate that long-term domiciliary HFNC treatment is very likely to be a cost-effective addition to usual care for COPD patients with chronic respiratory failure. The results must be interpreted in light of the uncertainty associated with the indirect estimation of health state utilities.

Comparison of high-flow nasal oxygen cannula therapy versus a standard oxygen face mask in patients with hypostatic pneumonia

Objective

We assessed the clinical effects of high-flow nasal cannula (HFNC) oxygen therapy and a standard oxygen atomizer mask on the respiratory tract in patients with hypostatic pneumonia.

Methods

We included patients with hypostatic pneumonia in this retrospective cohort study. Patients were provided continuous airway humidification by continuous oxygen atomization using either an HFNC or standard oxygen mask. Arterial blood gas analysis, the dyspnea score, inflammatory-related parameters, and adverse events of patients in the two groups were compared.

Results

Fifty-five patients had HFNC delivery and 57 had a standard oxygen atomizer mask. After 7 days of treatment, patients in the HFNC group had a higher partial pressure of arterial blood oxygen/fraction of inspired oxygen ratio (268.12±28.44 vs 238.28±30.04) and lower partial pressure of arterial blood carbon dioxide (38.02±8.84 vs 49.27±7.84 mmHg) than those in the standard oxygen mask group. The dyspnea score and inflammatory-related parameters in the HFNC group were significantly lower than those in the standard oxygen mask group. The incidence of adverse events was lower in the HFNC group than in the standard oxygen mask group.

Conclusion

HFNC therapy relieves clinical symptoms more quickly than a standard oxygen mask and reduces the incidence of adverse events.

The effect of Oxygen application with nCPAP for the prevention of desaturation during EBUS-TBNA

PURPOSE

EBUS-TBNA is a frequently used diagnostic method for mediastinal/hilar lymphadenopathies and masses. This procedure is performed with intravenous sedation (IVS). During IVS, patients often develop hypoxemia and nasal oxygen delivery is insufficient in some patients. The aim of this study was to investigate the effect of oxygen application with nCPAP on hypoxemia during EBUS-TBNA.

METHODS

Patients with EBUS-TBNA indication who did not have any serious heart-lung disease were randomly divided into two groups. One group received only oxygen and the other group received nCPAP+oxygen. Patient characteristics, arterial oxygen saturations, anesthetic agents, CPAP pressures, oxygen concentrations and processing times were recorded during the procedure. Practitioner satisfaction was evaluated at the end.

RESULTS

29 nCPAP+oxygen, 31 oxygen patients were included in the study. There were no significant differences in terms of age, sex, smoking history and presence of additional diseases in two groups. Neck circumference, BMI and STOP BANG questionnaire values were similar. Desaturation time was significantly longer in oxygen group than nCPAP+oxygen group (316±390 sec, 12±118 sec, respectively, p=0,019). Snoring was detected during the procedure in 22 patients in the oxygen group and in 11 patients in the nCPAP group (p=0,01). There were no serious complications in both groups. Practitioner satisfaction was higher in the nCPAP group but this was not statistically significant (p=0,052).

CONCLUSION

Oxygen application by nCPAP during EBUS-TBNA under IVS, significantly reduces desaturation time. Oxygen delivery with nCPAP seems to be a better choice especially for the patients with high Mallampati index.

Acute Responses to Oxygen Delivery via High Flow Nasal Cannula in Patients with Severe Chronic Obstructive Pulmonary Disease-HFNC and Severe COPD

Differences in oxygen delivery methods to treat hypoxemia have the potential to worsen CO₂ retention in chronic obstructive lung disease (COPD). Oxygen administration using high flow nasal cannula (HFNC) has multiple physiological benefits in treating respiratory failure including reductions in PaCO₂ in a flow-dependent manner. We hypothesized that patients with COPD would develop worsening hypercapnia if oxygen fraction was increased without increasing flow rate. We evaluated the acute response to HFNC in subjects with severe COPD when flow remained constant and inspired oxygen was increased. In total, 11 subjects with severe COPD (FEV1 < 50%) on supplemental oxygen with baseline normocapnia (PaCO₂ < 45 mm Hg; n = 5) and hypercapnia (PaCO₂ ≥ 45 mm Hg; n = 6) were studied. Arterial blood gas responses were studied at three timepoints: Baseline, HFNC at a flow rate of 30 L/min at resting oxygen supplementation for 1 h, and FiO₂ 30% above baseline with the same flow rate for the next hour. The primary endpoint was the change in PaCO₂ from baseline. No significant changes in PaCO₂ were noted in response to HFNC applied at baseline FiO₂ in the normocapnic and hypercapnic group. At HFNC with FiO₂ 30% above baseline, the normocapnic group did not show a change in PaCO₂ (baseline: 38.9 ± 1.8 mm Hg; HFNC at higher FiO₂: 38.8 ± 3.1 mm Hg; p = 0.93), but the hypercapnic group demonstrated significant increase in PaCO₂ (baseline: 58.2 ± 9.3 mm Hg; HFNC at higher FiO₂: 63.3 ± 10.9 mm Hg; p = 0.025). We observed worsening hypercapnia in severe COPD patients and baseline hypercapnia who received increased oxygen fraction when flow remained constant. These data show the need for careful titration of oxygen therapy in COPD patients, particularly those with baseline hypercapnia when flow rate is unchanged.

Comparison of high-flow oxygenation with noninvasive ventilation in COPD exacerbation: A crossover clinical trial

OBJECTIVES

To compare the therapeutic effects of high-flow-oxygen-Therapy (HFT) and noninvasive-ventilation (NIV) for stabilizing chronic obstructive pulmonary disease during exacerbation.

METHODS

In this randomized clinical trial at Masih-Daneshvari hospital, between July 2019 and Oct 2019, 30 exacerbated-COPD-patient with PaCO₂ 64.58 ± 11.61 mm Hg, Respiratory Rate 24.43 ± 2.75, and PH 7.31 ± 0.02 were divided into two groups, N = 15. By a simple randomized allocation, patients receive either NIV or HFT for 1 hour, and following a washout period of 30 minutes, they switched to the other treatment option. Arterial Blood Gas Parameters, as well as Respiratory Rate (RR), Dyspnea Score, Heart Rate (HR), and Oxygen Saturation (SO₂ ), were compared before and after the intervention and between groups.

RESULTS

Baseline patient characteristics were similar in the two groups. Pre and post-analysis revealed that in both groups, all improved significantly. After the first period, there was no difference in all parameters between groups except for SO₂ which was significantly higher in HFT (%92.1 ± 1) than that of NIV (%89 ± 1), P = .001. Likewise, following the washout period, patients in HFT and NIV had a dyspnea score of 1.93 ± 0.7 and 2.73 ± 0.9, respectively, P = .01. No carryover-effect and was observed but the period effect was significant for some outcomes. A significant improvement in SO₂ and HR was observed by HFT according to treatment effect by combining two periods' results. During the study, no side effects were reported.

CONCLUSION

In this short-term study HFT appears feasible for patients with COPD exacerbation to reduce dyspnea score and improve respiratory distress.

[Guideline for Long-Term Oxygen Therapy - S2k-Guideline Published by the German Respiratory Society]

Long-term oxygen therapy is of great importance both for reducing mortality and for improving performance in patients with chronic lung diseases. The prerequisites for Long-term oxygen therapy are adequate diagnostics and clearly defined indication. A causal distinction into chronic hypoxaemic and hypercapnic respiratory failure is reasonable, from which the differential indication for non-invasive ventilation results.The revised guideline covers the diagnostics and indication of chronic lung and heart diseases, the role of oxygen in terminal illness and gives a detailed description of available oxygen devices. The guideline is intended to help avoid undersupply, oversupply and false prescriptions. Furthermore, the chapter "Postacute Oxygen Therapy" discusses the procedure, relevant in everyday life, but not yet clearly defined, for prescribing oxygen therapy for the home at the end of an inpatient stay. Another important point, the correct prescription of mobile oxygen systems, is also presented in the guideline. This document is a revised version of the guideline for longterm oxygen therapy and replaces the version of 2008.

Effects of nasal high flow on nocturnal hypercapnia, sleep, and sympathovagal balance in patients with neuromuscular disorders

PURPOSE

In neuromuscular disorders (NMD), inspiratory muscle weakness may cause sleep-related hypoventilation requiring non-invasive ventilation (NIV). Alternatively, nasal high flow therapy (NHF) may ameliorate mild nocturnal hypercapnia (NH) through washout of anatomical dead space and generation of positive airway pressure. Ventilatory support by NIV or NHF might have favourable short-term effects on sympathovagal balance (SVB). This study comparatively investigated the effects of NHF and NIV on sleep-related breathing and SVB in NMD patients with evolving NH.

METHODS

Transcutaneous CO₂ (p_tcCO₂), peripheral oxygen saturation (SpO₂), sleep outcomes and SVB (spectral analysis of heart rate, diastolic blood pressure variability) along with haemodynamic measures (cardiac index, total peripheral resistance index) were evaluated overnight in 17 patients. Polysomnographies (PSG) were randomly split into equal parts with no treatment, NIV and NHF at different flow rates (20 l/min vs. 50 l/min). In-depth analysis of SVB and haemodynamics was performed on 10-min segments of stable N2 sleep taken from each intervention.

RESULTS

Compared with no treatment, NHF20 and NHF50 did not significantly change p_tcCO₂, SpO₂ or the apnea hypopnea index (AHI). NHF50 was poorly tolerated. In contrast, NIV significantly improved both gas exchange and AHI without adversely affecting sleep. During daytime, NHF20 and NHF50 had neutral effects on ventilation and oxygenation whereas NIV improved p_tcCO₂ and SpO₂. Effects of NIV and NHF on SVB and haemodynamics were neutral during both night and daytime.

CONCLUSIONS

NHF does not correct sleep-disordered breathing in NMD patients with NH. Both NHF and NIV exert no immediate effects on SVB.

The Mechanisms of Benefit of High-Flow Nasal Therapy in Stable COPD

High-flow nasal therapy (HFNT) is a unique system that delivers humidified, heated oxygen-enriched air via nasal cannula at high flow rates. It is a promising therapy for chronic obstructive pulmonary disease (COPD) patients. Several studies have examined the physiologic effects of this therapy in the patient population and have revealed that it improves mucociliary clearance, reduces nasopharyngeal dead space, and subsequently increases CO₂ washout. It also improves alveolar recruitment and gas exchange. These mechanisms may explain the promising results observed in recently published studies that examined the role of HFNT in stable COPD patients.

Development in PaCO2 over 12 months in patients with COPD with persistent hypercapnic respiratory failure treated with high-flow nasal cannula-post-hoc analysis from a randomised controlled trial

INTRODUCTION

Persistent hypercapnic failure in chronic obstructive pulmonary disease (COPD) is associated with poor prognosis. Long-term home non-invasive ventilation is recommended for patients with PaCO2 >7.0 kPa. Domiciliary high-flow nasal cannula (HFNC) reduces PaCO2 in short-term studies. This post-hoc analysis examines the effect of HFNC on PaCO2 levels, exacerbations and admissions in patients with COPD with persistent hypercapnic and hypoxic failures.

METHODS

The original trial included 74 long-term oxygen-treated patients (31 HFNC treated/43 controls) with persistent hypercapnic failure (PaCO2 >6 kPa) who completed the 12-month study period. Baseline data included age, sex, blood gases, exacerbations and hospital admissions in the previous year. Data on blood gases were also recorded at 6 and 12 months for all patients. In addition, acute changes in blood gases after 30 min of HFNC use at site visits were examined, as were exacerbations and hospital admissions during study.

RESULTS

Patients were comparable at baseline. After 12 months there was a 1.3% decrease in PaCO2 in patients using HFNC and a 7% increase in controls before HFNC use on site (p=0.003). After 30 min of HFNC at visits PaCO2 changed significantly, with comparable reductions, at 0, 6 and 12 months, including for controls who tried HFNC at study end (p<0.001). The exacerbation rate increased, compared with 12 months prestudy, by 2.2/year for controls (p<0.001) and 0.15/year for HFNC-treated patients (p=0.661). Hospital admission rates increased in the control group,+0.3/year from prestudy (p=0.180), And decreased by 0.67/year (p=0.013)for HFNC-treated patients.

CONCLUSION

This post-hoc analysis indicates that HFNC stabilises patients with COPD with persistent hypoxic and hypercapnic failures, in terms of PaCO2, exacerbations and number of hospitalisations, whereas those not receiving HFNC worsened. This suggests that HFNC is a possible treatment for patients with persistent hypercapnic COPD.

Treatment of severe stable COPD: the multidimensional approach of treatable traits

Now that additional treatment options for severe chronic obstructive pulmonary disease (COPD) have emerged in recent years, patients with severe COPD should not be left in the rather hopeless situation of "there is nothing to improve" any more. Inertia or fatalism is a disservice to our patients. Ranging from advanced care planning to quite intense and demanding therapies such as multidisciplinary pulmonary rehabilitation, (endoscopic) lung volume reduction, chronic noninvasive ventilation and lung transplantation, caregivers should try to provide a personalised treatment for every severe COPD patient. In this review, we aim to describe the multidimensional approach to these patients at our centre along the lines of treatable traits leading to specific additional treatment modalities on top of standard care.

High Flow Through Nasal Cannula in Stable and Exacerbated Chronic Obstructive Pulmonary Disease Patients

BACKGROUND

High-Flow through Nasal Cannula (HFNC) is a system delivering heated humidified air-oxygen mixture at a flow up to 60 L/min. Despite increasing evidence in hypoxemic acute respiratory failure, a few is currently known in chronic obstructive pulmonary disease (COPD) patients.

OBJECTIVE

To describe the rationale and physiologic advantages of HFNC in COPD patients, and to systematically review the literature on the use of HFNC in stable and exacerbated COPD patients, separately.

METHODS

A search strategy was launched on MEDLINE. Two authors separately screened all potential references. All (randomized, non-randomized and quasi-randomized) trials dealing with the use of HFNC in both stable and exacerbated COPD patients in MEDLINE have been included in the review.

RESULTS

Twenty-six studies have been included. HFNC: 1) provides heated and humidified airoxygen admixture; 2) washes out the anatomical dead space of the upper airway; 3) generates a small positive end-expiratory pressure; 4) guarantees a more stable inspired oxygen fraction, as compared to conventional oxygen therapy (COT); and 5) is more comfortable as compared to both COT and non-invasive ventilation (NIV). In stable COPD patients, HFNC improves gas exchange, the quality of life and dyspnea with a reduced cost of muscle energy expenditure, compared to COT. In exacerbated COPD patients, HFNC may be an alternative to NIV (in case of intolerance) and to COT at extubation or NIV withdrawal.

CONCLUSION

Though evidence of superiority still lacks and further studies are necessary, HFNC might play a role in the treatment of both stable and exacerbated COPD patients.

Characteristics and outcome of patients set up on high-flow oxygen therapy at home

Background:

High-flow oxygen therapy (HFOT) is increasingly used for acute respiratory failure. Few data support its use at home for the treatment of chronic respiratory failure. Our aim was to report the pattern of the use of long-term HFOT in our center and the outcome of patients setup on long-term HFOT.

Methods:

A retrospective monocentric study including all patients setup on long-term HFOT between January 2011 and April 2018 in Rouen University Hospital was carried out. Patients were divided into two groups, patients with hypoxemic respiratory failure treated with nasal HFOT (nHFOT) and tracheotomized patients treated with tracheal HFOT (tHFOT).

Results:

A total of 71 patients were established on long-term HFOT. Out of these 43 (61%) were included in the nHFOT group and 28 (39%) were included in the tHFOT group. In the nHFOT group, underlying respiratory diseases were interstitial lung disease (n = 15, 35%), pulmonary hypertension (n = 12, 28%), lung cancer (n = 9, 21%), and chronic airway disease (n = 7, 16%). In the tHFOT group, the number of admissions for exacerbation decreased by −0.78 per year (–2 to 0) (p = 0.045). In total, 51 (72%) patients were discharged to their homes and 20 (28%) went to a post-acute re-enablement facility. Median survival following HFOT was 7.5 months. Survival was significantly lower in the nHFOT group with a median survival of 3.6 months whereas median survival was not reached in the tHFOT group (p < 0.001). Monthly costs associated with home delivery of HFOT were €476 (296–533) with significant differences in costs between the nHFOT group of €520 (408–628) and costs in the tHFOT group of €296 (261–475) (p < 0.001).

Conclusions:

The use of long-term HFOT allows very severe patients to be discharged at a reasonable cost from acute care facilities.

The reviews of this paper are available via the supplementary material section.

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

Severe bronchial asthma complicated with respiratory failure, a common critical illness in respiratory medicine, may be life-threatening. High-flow nasal cannula (HFNC) is a novel oxygen therapy technique developed in recent years. HFNC was applied in this study for treating adult patients with severe bronchial asthma complicated with respiratory failure. Its efficacy was analyzed comparatively to conventional oxygen therapy (COT). HFNC and COT were randomly performed based on conventional treatment. The HFNC group was similar to COT-treated patients in terms of response rate, with no significant difference in efficacy between the two groups. In patients with bronchial asthma, effectively increased PO₂ and reduced PCO₂ were observed after treatment in both groups. However, HFNC was more efficient than COT in elevating PO₂ in patients with severe bronchial asthma complicated with respiratory failure, while no statistically significant difference in PCO₂ reduction was found between the two groups. Heart rate (HR) and respiratory rate (RR) between the two groups on admission (0 h) and at 2, 8, 24, and 48 h after admission were compared. Both indicators significantly decreased with time. No significant differences in HR and RR were found between the groups at 0, 2, and 8 h after admission. However, these indicators were significantly lower in the HFNC group compared with the COT group at 24 and 48 h after admission. HFNC could significantly elevate PO₂ and reduce HR and RR. Thus, it is a promising option for patients with severe bronchial asthma complicated with respiratory failure.

Clinical Evidence of Nasal High-Flow Therapy in Chronic Obstructive Pulmonary Disease Patients

Nasal high-flow therapy (NHFT) is an upcoming treatment for chronic obstructive pulmonary disease (COPD) patients. It supplies heated, humidified, and, desirably, oxygen-enriched air through a nasal cannula at flow rates up to 60 L/min. Several studies examined the effect of NHFT in COPD patients, but a clear overview is lacking. The present review aimed to give an overview of the clinical evidence of NHFT in 3 aspects of COPD care: long-term use in stable COPD patients, use for treatment of COPD exacerbations, and use during exercise therapy in COPD. For each topic, a specific literature search was performed up to December 9, 2019. Studies show promising results, with most evidence for its long-term use in hypoxemic COPD patients that frequently exacerbate, and very limited evidence for its use during COPD exacerbations or as a worthwhile adjunct to exercise training. More evidence is therefore needed to know how to incorporate NHFT in standard clinical practice.

Nasal High Flow Use in COPD Patients with Hypercapnic Respiratory Failure: Treatment Algorithm & Review of the Literature

Nasal high flow (NHF) therapy has recently gained attention as a new respiratory support system and is increasingly being utilized in every day clinical practice. Recent studies suggest that it may also be effective in patients with hypercapnia and suggest NHF as a possible alternative for patients who cannot tolerate standard noninvasive ventilation. The present review discusses the mechanisms of action that make NHF potentially suitable for chronic obstructive pulmonary disease (COPD) patients and evaluates the current evidence of NHF use for treatment of stable hypercapnic COPD patients as well as acute hypercapnic exacerbation of COPD. An algorithm is also proposed for the clinical application of NHF in patients with acute hypercapnic exacerbation of COPD, based on current literature.

Effects of high-flow nasal cannula in patients with persistent hypercapnia after an acute COPD exacerbation: a prospective pilot study

BACKGROUND

Persistent hypercapnia after COPD exacerbation is associated with excess mortality and early rehospitalization. High Flow Nasal cannula (HFNC), may be theoretically an alternative to long-term noninvasive ventilation (NIV), since physiological studies have shown a reduction in PaCO2 level after few hours of treatment. In this clinical study we assessed the acceptability of HFNC and its effectiveness in reducing the level of PaCO₂ in patients recovering from an Acute Hypercapnic Respiratory Failure (AHRF) episode. We also hypothesized that the response in CO₂ clearance is dependent on baseline level of hypercapnia.

METHODS

Fifty COPD patients recovering from an acute exacerbation and with persistent hypercapnia, despite having attained a stable pH (i.e. pH > 7,35 and PaCO₂ > 45 mmHg on 3 consecutive measurements), were enrolled and treated with HFNC for at least 8 h/day and during the nighttime RESULTS: HFNC was well tolerated with a global tolerance score of 4.0 ± 0.9. When patients were separated into groups with or without COPD/OSA overlap syndrome, the "pure" COPD patients showed a statistically significant response in terms of PaCO₂ decrease (p = 0.044). In addition, the subset of patients with a lower pH at enrolment were those who responded best in terms of CO₂ clearance (score test for trend of odds, p = 0.0038).

CONCLUSIONS

HFNC is able to significantly decrease the level of PaCO₂ after 72 h only in "pure" COPD patients, recovering from AHRF. No effects in terms of CO2 reduction were found in those with overlap syndrome. The present findings will help guide selection of the best target population and allow a sample size calculation for future long-term randomized control trials of HFNC vs NIV.

TRIAL REGISTRATION

This study is registered with www. clinicaltrials.gov with identifier number NCT03759457.

Use High-Flow Nasal Cannula for Acute Respiratory Failure Patients in the Emergency Department: A Meta-Analysis Study

Objective

To evaluate the efficacy of high-flow nasal cannula (HFNC) therapy compared with conventional oxygen therapy (COT) or noninvasive ventilation (NIV) for the treatment of acute respiratory failure (ARF) in emergency departments (EDs).

Method

We comprehensively searched 3 databases (PubMed, EMBASE, and the Cochrane Library) for articles published from database inception to 12 July 2019. This study included only randomized controlled trials (RCTs) that were conducted in EDs and compared HFNC therapy with COT or NIV. The primary outcome was the intubation rate. The secondary outcomes were the mortality rate, intensive care unit (ICU) admission rate, ED discharge rate, need for escalation, length of ED stay, length of hospital stay, and patient dyspnea and comfort scores.

Result

Five RCTs (n = 775) were included. There was a decreasing trend regarding the application of HFNC therapy and the intubation rate, but the difference was not statistically significant (RR, 0.53; 95% CI, 0.26–1.09; p=0.08; I² = 0%). We found that compared with patients who underwent COT, those who underwent HFNC therapy had a reduced need for escalation (RR, 0.41; 95% CI, 0.22–0.78; p=0.006; I² = 0%), reduced dyspnea scores (MD −0.82, 95% CI −1.45 to −0.18), and improved comfort (SMD −0.76 SD, 95% CI −1.01 to −0.51). Compared with the COT group, the HFNC therapy group had a similar mortality rate (RR, 1.25; 95% CI, 0.79–1.99; p=0.34; I² = 0%), ICU admission rate (RR, 1.11; 95% CI, 0.58–2.12; p=0.76; I² = 0%), ED discharge rate (RR, 1.04; 95% CI, 0.63–1.72; p=0.87; I² = 0%), length of ED stay (MD 1.66, 95% CI −0.95 to 4.27), and hospital stay (MD 0.9, 95% CI −2.06 to 3.87).

Conclusion

Administering HFNC therapy in ARF patients in EDs might decrease the intubation rate compared with COT. In addition, it can decrease the need for escalation, decrease the patient's dyspnea level, and increase the patient's comfort level compared with COT.

Dose Response to Transnasal Pulmonary Administration of Bronchodilator Aerosols via Nasal High-Flow Therapy in Adults with Stable Chronic Obstructive Pulmonary Disease and Asthma

BACKGROUND

There has been increasing interest in transnasal pulmonary aerosol administration, but the dose-response relationship has not been reported.

OBJECTIVES

To determine the accumulative bronchodilator dose at which patients with stable mild-to-moderate asthma and chronic obstructive pulmonary disease (COPD) achieve similar spirometry responses before and after bronchodilator tests using albuterol via a metered dose inhaler with a valved holding chamber (MDI + VHC).

METHOD

Adult patients who met ATS/ERS criteria for bronchodilator responses in pulmonary function laboratory were recruited and consented to participate. After a washout period, patients received escalating doubling dosages (0.5, 1, 2, and 4 mg) of albuterol in a total volume of 2 mL delivered by vibrating mesh nebulizer via a nasal cannula at 37°C with a flow rate of 15-20 L/min using a Venturi air entrainment device. Spirometry was measured at baseline and after each dose. Titration was stopped when an additional forced expiratory volume in 1 second (FEV1) improvement was <5%.

RESULTS

42 patients (16 males) with stable mild-to-moderate asthma (n = 29) and COPD (n = 13) were enrolled. FEV1 increment after a cumulative dose of 1.5 mg of albuterol via nasal cannula at 15-20 L/min was similar to 4 actuations of MDI + VHC (0.34 ± 0.18 vs. 0.34 ± 0.12 L, p = 0.878). Using ATS/ERS criteria of the bronchodilator test, 33.3% (14/42) and 69% (29/42) of patients responded to 0.5 and 1.5 mg of albuterol, respectively.

CONCLUSIONS

With a nasal cannula at 15-20 L/min, transnasal pulmonary delivery of 1.5 mg albuterol resulted in similar bronchodilator response as 4 actuations of MDI + VHC.

Nasal high-flow versus noninvasive ventilation in patients with chronic hypercapnic COPD

Background

Despite the encouraging results of noninvasive ventilation (NIV) in chronic hypercapnic COPD patients, it is also evident that some patients do not tolerate NIV or do not benefit from it. We conducted a study in which COPD patients with stable, chronic hypercapnia were treated with NIV and nasal high-flow (NHF) to compare effectiveness.

Methods

In a multi-centered, randomized, controlled, cross-over design, patients received 6 weeks of NHF ventilation followed by 6 weeks of NIV ventilation or vice-versa (TIBICO) between 2011 and 2016. COPD patients with stable daytime hypercapnia (pCO₂≥50 mmHg) were recruited from 13 German centers. The primary endpoint was pCO₂ changes from baseline blood gas, lung function, quality of life (QoL), the 6 min walking test, and duration of device use were secondary endpoints.

Results

A total of 102 patients (mean±SD) age 65.3±9.3 years, 61% females, body mass index 23.1±4.8 kg/m², 90% GOLD D, pCO₂ 56.5±5.4 mmHg were randomized. PCO₂ levels decreased by 4.7% (n=94; full analysis set; 95% CI 1.8-7.5, P=0.002) using NHF and 7.1% (95% CI 4.1-10.1, P<0.001) from baseline using NIV (indistinguishable to intention-to-treat analysis). The difference of pCO₂ changes between the two devices was -1.4 mmHg (95% CI -3.1-0.4, P=0.12). Both devices had positive impact on blood gases and respiratory scores (St. George's Respiratory Questionnaire, Severe Respiratory Insufficiency Questionnaire).

Conclusions

NHF may constitute an alternative to NIV in COPD patients with stable chronic hypercapnia, eg, those not tolerating or rejecting NIV with respect to pCO₂ reduction and improvement in QoL.

Domiciliary High-Flow Nasal Cannula Oxygen Therapy for Patients with Stable Hypercapnic Chronic Obstructive Pulmonary Disease. A Multicenter Randomized Crossover Trial

RATIONALE

A growing evidence base suggests a benefit of using high-flow nasal cannula oxygen therapy in the acute setting. However, the clinical benefit of domiciliary use of high-flow nasal cannula oxygen therapy in patients with chronic hypercapnic respiratory failure due to chronic obstructive pulmonary disease remains unclear.

OBJECTIVES

To evaluate the efficacy and safety of high-flow nasal cannula oxygen therapy use in patients with stable chronic obstructive pulmonary disease.

METHODS

We conducted a multicenter, randomized crossover trial comparing high-flow nasal cannula oxygen therapy plus long-term oxygen therapy with long-term oxygen therapy only in 32 adults with stable hypercapnic chronic obstructive pulmonary disease. Participants were randomized to receive either 6 weeks of high-flow nasal cannula oxygen therapy/long-term oxygen therapy using the myAIRVO 2 device followed by another 6 weeks of long-term oxygen therapy only or long-term oxygen therapy only followed by high-flow nasal cannula oxygen therapy/long-term oxygen therapy. The primary outcome was the change in quality of life as assessed by St. George's Respiratory Questionnaire for chronic obstructive pulmonary disease. A linear mixed-effects model was used to account for treatment effect, time effect, allocation effect, and participant effect.

RESULTS

Of 32 study participants, 29 completed the study. At the end of 12 weeks, high-flow nasal cannula oxygen therapy/long-term oxygen therapy treatment improved the mean total St. George's Respiratory Questionnaire for chronic obstructive pulmonary disease score compared with long-term oxygen therapy only (7.8 points; 95% confidence interval, 3.7 to 11.9; P < 0.01). Similarly, high-flow nasal cannula oxygen therapy/long-term oxygen therapy treatment improved the arterial partial pressure of carbon dioxide (adjusted treatment effect, -4.1 mm Hg; 95% confidence interval, -6.5 to -1.7 mm Hg), pH (adjusted treatment effect, +0.02; 95% confidence interval, 0.01 to 0.02), and median nocturnal transcutaneous carbon dioxide pressure (adjusted treatment effect, -5.1 mm Hg; 95% confidence interval, -8.4 to -1.8 mm Hg). High-flow nasal cannula oxygen therapy/long-term oxygen therapy treatment did not improve the arterial partial pressure of oxygen, dyspnea, spirometry, lung volume, 6-minute walk test, or physical activity. The most frequent high-flow nasal cannula oxygen therapy-related adverse event encountered was nocturnal sweating (n = 6 [20.7%]). Four severe adverse events occurred (two in each group) and were deemed unrelated to the intervention.

CONCLUSIONS

Six weeks of treatment with high-flow nasal cannula oxygen therapy improved health-related quality of life and reduced hypercapnia in patients with stable hypercapnic chronic obstructive pulmonary disease. Clinical trial registered with www.clinicaltrials.gov (NCT02545855) and www.umin/ac.jp (UMIN000017639).

A prospective randomized comparative study of high-flow nasal cannula oxygen and non-invasive ventilation in hypoxemic patients undergoing diagnostic flexible bronchoscopy

Background

Although oxygen supplementation during bronchoscopy in patients with pre-existing hypoxemia is provided, adequacy of oxygenation may not be achieved, resulting in the occurrence of respiratory failure that requires endotracheal tube intubation. The purpose of this study was to compare high-flow nasal cannula (HFNC) with non-invasive ventilation (NIV) in patients with pre-existing hypoxemia undergoing flexible bronchoscopy (FB) on the ability to maintain oxygen saturation during bronchoscopy.

Methods

A prospective randomized study was conducted in patients who had hypoxemia [defined as partial pressure of arterial oxygen (PaO₂) less than 70 mmHg at room air] and required FB for the diagnosis of abnormal pulmonary lesions. Patients were randomized to receive either HFNC or NIV during FB. The primary outcome was the lowest oxygen saturation level during FB.

Results

Fifty-one patients underwent randomization to HFNC (n=26) or NIV (n=25). Baseline characteristics in terms of age, Simplified Acute Physiologic Score II values, and cardiorespiratory parameters were similar in both groups. After receiving HFNC or NIV, oxygen saturation as measured by pulse oximeter (SpO₂) increased to greater than 90% in all cases. During FB, although the lowest SpO₂ was similar in both groups, the lowest SpO₂ <90% tended to occur more often in the HFNC group (34.6% vs. 12.0%; P=0.057). In patients with baseline PaO₂ <60 mmHg on ambient air, a decrease in PaO₂ from preprocedure to the end of FB was less in the NIV group (-13.7 vs. -57.0 mmHg; P=0.019). After FB, the occurrence of SpO₂ <90% was 15.4% and 4.0% in the HFNC group and NIV group, respectively (P=0.17).

Conclusions

In overall, NIV and HFNC provided the similar effectiveness in prevention of hypoxemia in hypoxemic patients undergoing FB. However, in subgroup analysis, NIV provided greater adequacy and stability of oxygenation than HFNC in patients with baseline PaO₂ <60 mmHg on ambient air.

Comparison of high flow nasal cannula with noninvasive ventilation in chronic obstructive pulmonary disease patients with hypercapnia in preventing postextubation respiratory failure: A pilot randomized controlled trial

High flow nasal cannula (HFNC) has been shown to improve extubation outcomes in patients with hypoxemia, but the role of HFNC in weaning patients with chronic obstructive pulmonary disease (COPD) with hypercapnia from invasive ventilation is unclear. We compared the effects of HFNC to noninvasive ventilation (NIV) on postextubation vital signs and arterial blood gases (ABGs) among patients with COPD. Other outcomes included comfort scores, need for bronchoscopy, use of pulmonary medications, and chest physiotherapy. Forty-two COPD patients who had persistent hypercapnia at extubation were assigned randomly to receive HFNC (22) or NIV (20). Twenty patients in each group were enrolled for per-protocol analysis with regard to primary outcomes. Vital signs and ABGs before extubation were similar between groups. At 3 hr after extubation, pH in the NIV group was lower than HFNC group (7.42 ± 0.06 vs. 7.45 ± 0.05, p = 0.01). At 24 hr after extubation, patients' mean arterial pressure (82.97 ± 9.04 vs. 92.06 ± 11.11 mmHg, p = 0.05) and pH (7.42 ± 0.05 vs. 7.46 ± 0.03, p = 0.05) in the NIV group were lower than in the HFNC group. No significant differences were found at 48 hr after extubation. In the HFNC group, comfort scores were better (3.55 ± 2.01 vs. 5.15 ± 2.28, p = 0.02) and fewer patients needed bronchoscopy for secretion management within 48 hr after extubation (2/22 vs. 9/20, p = 0.03). HFNC is a potential alternative to NIV to wean hypercapnic COPD patients with regard to vital signs and ABGs, HFNC improved patients' comfort and secretion clearance.

Non-invasive ventilation or high-flow oxygen therapy: When to choose one over the other?

It has been found that high-flow oxygen therapy (HFOT) can reduce mortality of patients admitted to intensive care unit (ICU) for de novo acute respiratory failure (ARF) as compared to non-invasive ventilation (NIV). HFOT might therefore be considered as a first-line strategy of oxygenation in these patients. The beneficial effects of HFOT may be explained by its good tolerance and by physiological characteristics including delivery of high FiO₂ , positive end expiratory pressure (PEEP) effect and continuous dead space washout contributing to decreased work of breathing. In contrast, NIV should be used cautiously in patients with de novo ARF due to high tidal volumes promoted by pressure support and that may potentially worsen pre-existing lung injury. Although recent studies have reported no benefit and even deleterious effects of NIV in immunocompromised patients with ARF, the experts have recommended its use as a first-line strategy. In patients with acute-on-chronic respiratory failure and respiratory acidosis, it has been clearly shown that NIV is the best strategy of oxygenation. However, HFOT seems able to reverse respiratory acidosis and further studies are needed to evaluate whether HFOT could represent an alternative to standard oxygen. Although NIV is recommended to treat ARF in post-operative patients or to prevent post-extubation respiratory failure in ICU, recent large-scale randomized studies suggest that HFOT could be equivalent to NIV. While recent recommendations have been established from studies comparing NIV with standard oxygen, new studies are needed to compare NIV versus HFOT in order to better define the appropriate indications for both treatments.

Nasal high flow, but not supplemental O2, reduces peripheral vascular sympathetic activity during sleep in COPD patients

Introduction

Patients with COPD have increased respiratory loads and altered blood gases, both of which affect vascular function and sympathetic activity. Sleep, particularly rapid eye movement (REM) sleep, is known to exacerbate hypoxia and respiratory loads. Therefore, we hypothesize that nasal high flow (NHF), which lowers ventilatory loads, reduces sympathetic activity during sleep and that this effect depends on COPD severity.

Methods

We performed full polysomnography in COPD patients (n=17; FEV₁, 1.6±0.6 L) and in matched controls (n=8). Participants received room air (RA) at baseline and single night treatment with O₂ (2 L/min) and NHF (20 L/min) in a random order. Finger pulse wave amplitude (PWA), a measure of vascular sympathetic tone, was assessed by photoplethysmography. Autonomic activation (AA) events were defined as PWA attenuation ≥30% and indexed per hour for sleep stages (AA index [AAI]) at RA, NHF, and O₂).

Results

In COPD, sleep apnea improved following O₂ (REM-apnea hypopnea index [AHI] with RA, O₂, and NHF: 18.6±20.9, 12.7±18.1, and 14.4±19.8, respectively; P=0.04 for O₂ and P=0.06 for NHF). REM-AAI was reduced only following NHF in COPD patients (AAI-RA, 21.5±18.4 n/h and AAI-NHF, 9.9±6.8 n/h, P=0.02) without changes following O₂ (NHF-O₂ difference, P=0.01). REM-AAI reduction was associated with lung function expressed as FEV₁ and FVC (FEV₁: r=−0.59, P=0.001; FEV₁/FVC: r=−0.52 and P=0.007).

Conclusion

NHF but not elevated oxygenation reduces peripheral vascular sympathetic activity in COPD patients during REM sleep. Sympathetic off-loading by NHF, possibly related to improved breathing mechanics, showed a strong association with COPD severity.

Comparison of high flow nasal cannula oxygen and conventional oxygen therapy on ventilatory support duration during acute-on-chronic respiratory failure: study protocol of a multicentre, randomised, controlled trial. The 'HIGH-FLOW ACRF' study

INTRODUCTION

This study protocol describes a trial designed to investigate whether high-flow heated and humidified nasal oxygen (HFHO) therapy in patients with hypercapnic acute respiratory failure (ARF) reduces the need of non-invasive ventilation (NIV).

METHODS AND ANALYSIS

This is an open-label, superiority, international, parallel-group, multicentre randomised controlled two-arm trial, with an internal feasibility pilot phase. 242 patients with hypercapnic ARF requiring NIV admitted to an intensive care unit, an intermediate care or a respiratory care unit will be randomised in a 1:1 ratio to receive HFHO or standard oxygen in between NIV sessions. Randomisation will be centralised and stratified by centre and pH at admission (pH ≤7.25 or >7.25). The primary outcome will be the number of ventilator-free days (VFDs) and alive at day 28 postrandomisation. The secondary outcomes will encompass parameters related to the VFDs, comfort and tolerance variables, hospital length of stay and mortality. VFDs at 28 days postrandomisation will be compared between the two groups by Wilcoxon-Mann-Whitney two-sample rank-sum test in the intention-to-treat population. A sensitivity analysis will be conducted in the population of patients for whom the criteria of switching from NIV to spontaneous breathing, or conversely, are not strictly verified.

ETHICS AND DISSEMINATION

The protocol has been approved by the Comité de Protection des Personnes (CPP) Sud-Ouest & Outre-Mer IV (ref CPP17-049a/2017-A01830-53) and will be carried out in accordance with the Declaration of Helsinki and Good Clinical Practice guidelines. A trial steering committee will oversee the progress of the study. Findings will be disseminated through national and international scientific conferences, and publication in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03406572.

Prevention of hypoxemia during endobronchial ultrasound-guided transbronchial needle aspiration: Usefulness of high-flow nasal cannula

BACKGROUND

Hypoxemia during endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is often encountered even in patients without respiratory impairment before the procedure. The aim of this study was to evaluate the efficacy of a high-flow nasal cannula (HFNC) in preventing hypoxemia during EBUS-TBNA.

METHODS

The present investigation was designed as a prospective pilot study. Eligible subjects were adults who could undergo EBUS-TBNA under intravenous midazolam sedation. The main exclusion criteria were as follows: age > 80 years with impaired oxygenation and peripheral oxygen saturation (SpO₂) < 95% at room air. The primary outcome was the oxygenation level during the procedure. Cutaneous carbon dioxide tension (PcCO₂) and complications were evaluated as secondary outcomes. HFNC use was started at an inspired O₂ fraction of 30% and was titrated to maintain SpO₂ over 90%. The lowest SpO₂ values during EBUS-TBNA were retrospectively compared between patients who underwent HFNC and those were given a conventional nasal cannula as a historical control group.

RESULTS

Twelve patients received HFNCs. The mean lowest SpO₂ during the procedure was 93%. Although the mean SpO₂ tended to decrease in the early stages, it remained over 90% throughout the procedure. The mean highest PcCO₂ was 39 mmHg (range, 30-46 mmHg). There were no major complications. In patients who underwent EBUS-TBNA using a conventional nasal cannula, the mean lowest SpO₂ was 88%, which was significantly lower than that in the HFNC cases (p = 0.005).

CONCLUSION

HFNC could be an effective and safe device for prevention of hypoxemia during EBUS-TBNA.

Effectiveness of high-flow nasal cannula oxygen therapy for acute respiratory failure with hypercapnia

Background

Heated and humidified high-flow nasal cannula (HFNC) oxygen therapy has recently been introduced for hypoxic respiratory failure. However, it has not been well-evaluated for acute respiratory failure with hypercapnia.

Methods

This retrospective study included acute respiratory failure patients with hypercapnia in the medical intensive care unit (MICU) from April 2011 to February 2013, who required HFNC oxygen therapy for hypoxemia. Respiratory parameters were recorded and arterial blood gas analyses conducted before, and at 1 and 24 h after initiation of HFNC oxygen therapy.

Results

Thirty-three patients were studied [median age, 72 years; range, 17-85 years; men, 24 (72.7%)]. Pneumonia (36.4%) and acute exacerbation of chronic obstructive pulmonary disease (33.4%) were the most common reasons for oxygen therapy. Most patients (60.6%) received oxygen therapy via nasal prong before HFNC application. The mean fraction of inspired oxygen (FiO₂) and HFNC flow rate were 0.45±0.2 and 41.1±7.1 L/min, respectively; mean duration of application was 3.6±4.1 days. The partial pressure of arterial carbon dioxide (PaCO₂) was 55.0±12.2 mmHg at admission, and increased by approximately 1.0±7.7 mmHg with conventional oxygen therapy. In contrast, with HFNC therapy, PaCO₂ decreased by 4.2±5.5 and 3.7±10.8 mmHg in 1 and 24 h, respectively, resulting in significant improvement in hypercapnia (P=0.006 and 0.062, respectively).

Conclusions

HFNC oxygen therapy with sufficient FiO₂ to maintain a normal partial pressure of arterial oxygen (PaO₂) significantly reduced PaCO₂ in acute respiratory failure with hypercapnia.

Effectiveness of nasal highflow in hypercapnic COPD patients is flow and leakage dependent

Background

Nasal Highflow (NHF) delivers a humidified and heated airflow via nasal prongs. Current data provide evidence for efficacy of NHF in patients with hypoxemic respiratory failure. Preliminary data suggest that NHF may decrease hypercapnia in hypercapnic respiratory failure. The aim of this study was to evaluate the mechanism of NHF mediated PCO₂ reduction in patients with chronic obstructive pulmonary disease (COPD).

Methods

In 36 hypercapnic COPD patients (PCO₂ > 45 mmHg), hypercapnia was evaluated by capillary gas sampling 1 h after NHF breathing under four conditions A to D with different flow rates and different degrees of leakage (A = 20 L/min, low leakage, two prongs, both inside; B = 40 L/min, low leakage, two prongs, both inside; C = 40 L/min, high leakage, two prongs, one outside and open; D = 40 L/min, high leakage, two prongs, one outside and closed). Under identical conditions, mean airway pressure was measured in the hypopharynx of 10 COPD patients.

Results

Hypercapnia significantly decreased in all patients. In patients with capillary PCO₂ > 55 mmHg (n = 26), PCO₂ additionally decreased significantly by increased leakage and/or flow rate in comparison to lower leakage/ flow rate conditions (A = 94.2 ± 8.2%; B = 93.5 ± 4.4%; C = 90.5 ± 7.2%; D = 86.8 ± 3.8%). The highest mean airway pressure was observed in patients breathing under condition B (2.3 ± 1.6 mbar; p < 0.05).

Conclusions

This study demonstrates effective PCO₂ reduction with NHF therapy in stable hypercapnic COPD patients. This effect does not correlate with an increase in mean airway pressure but with increased leakage and airflow, indicating airway wash out and reduction of functional dead space as important mechanisms of NHF therapy. These results may be useful when considering NHF treatment in hypercapnic COPD patients.

Trial registration

Clinical Trials: NCT02504814; First posted July 22, 2015.

Oral Versus Nasal High-Flow Bronchodilator Inhalation in Chronic Obstructive Pulmonary Disease

BACKGROUND

Nasal high flow (NHF) alters breathing patterns, stabilizes fraction of inspired oxygen (FiO2) during respiratory distress, helps to keep up hemostasis in the airways, and washes out the upper airways. Particularly the support of inspiratory flow and decrease in functional dead space are interesting mechanisms of action with regard to aerosol delivery. Several laboratory investigations have studied aerosol delivery via the nasal route by using NHF, whereas clinical benefits are poorly evaluated.

METHODS

Thirty patients with stable chronic obstructive pulmonary disease Gold D were recruited. In a randomized order, they inhaled a salbutamol 2.5 mg/ipratropium bromide 500 μg solution oral or NHF adapted on the second study day. A jet nebulizer was used as aerosol delivery device. The chosen flow rate was 35 L/min.

RESULTS

Four patients refused to repeat the procedure, for example, for inconvenience or fear of delayed discharge, and were not included in the intention-to-treat analysis. All remaining patients tolerated both inhalation systems well. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), airway resistance (Rtot), and residual volume (RV) were significantly altered after bronchodilator inhalation with each of the both devices. The two different ways of combined bronchodilator inhalation resulted in very comparable changes in FVC, FEV1, relative 1 second-capacity (FEV1%FVC), Rtot, total lung capacity (TLC), RV, and residual volume expressed as percent of TLC (RV%TLC). However, in between devices, no difference was observed on comparing the postinhalational measurements of FVC, FEV1, Rtot, and RV.

CONCLUSIONS

We conclude from this proof-of-principle kind of study that inhalation of combined bronchodilators adapted to an NHF device is similarly effective to inhalation with a standard oral aerosol nebulizer. (Clinical Trails NCT02885103).

Nasal high flow therapy: a novel treatment rather than a more expensive oxygen device

Nasal high flow is a promising novel oxygen delivery device, whose mechanisms of action offer some beneficial effects over conventional oxygen systems. The administration of a high flow of heated and humidified gas mixture promotes higher and more stable inspiratory oxygen fraction values, decreases anatomical dead space and generates a positive airway pressure that can reduce the work of breathing and enhance patient comfort and tolerance. Nasal high flow has been used as a prophylactic tool or as a treatment device mostly in patients with acute hypoxaemic respiratory failure, with the majority of studies showing positive results. Recently, its clinical indications have been expanded to post-extubated patients in intensive care or following surgery, for pre- and peri-oxygenation during intubation, during bronchoscopy, in immunocompromised patients and in patients with “do not intubate” status. In the present review, we differentiate studies that suggest an advantage (benefit) from other studies that do not suggest an advantage (no benefit) compared to conventional oxygen devices or noninvasive ventilation, and propose an algorithm in cases of nasal high flow application in patients with acute hypoxaemic respiratory failure of almost any cause.

Evaluation by various methods of the physiological mechanism of a high-flow nasal cannula (HFNC) in healthy volunteers

INTRODUCTION

Several reports have described the usefulness of a high-flow nasal cannula (HFNC). However, the physiological mechanisms of this system are unclear. In the current study, various methods were used to investigate the physiological mechanisms of an HFNC in healthy volunteers.

METHODS

The physiological mechanisms of the constant-flow and constant-pressure models of HFNC were studied in 10 healthy volunteers by the oesophageal balloon method, the electrical impedance method and the forced oscillation technique (FOT).

RESULTS

The tidal volume (TV) increased markedly during HFNC (off, 30 L/min, 50 L/min: 685.6±236.5 mL, 929.8±434.7 mL, 968.8±451.1 mL). The end-inspiratory oesophageal pressure (EIOP) was not significantly different, but there was a tendency for it to decrease. HFNC 30 L/min and 50 L/min, the increment in TV and the difference in EIOP showed strong negative correlations (p=0.0025, 0.003). The end-expiratory oesophageal pressure (EEOP) increased. The respiratory system reactance at 5 Hz (X5) by FOT decreased significantly. There was a flow rate-dependent EEOP increase, and the positive end-expiratory pressure (PEEP) effect of HFNC was confirmed. There was a correlation between the difference in X5 and the difference in EEOP during HFNC 30 L/min and 50 L/min, with correlation coefficients of 0.534 and 0.404 (p=0.112, 0.281). The amount of change in EEOP and the fluctuation in X5 were positively correlated.

CONCLUSIONS

The PEEP effect of HFNC was confirmed by the electrical impedance method and FOT. The increment in TV and the difference in EIOP of HFNC showed strong negative correlations.

Use of Nasal High Flow in Stable COPD: Rationale and Physiology

High-flow nasal cannula (HFNC) is a device able to deliver heated and humidified oxygen at high flows (up to 60 L/minutes). Potential benefits of HFNC are several and include the improvement of lung mucociliary clearance, the washout of upper airway dead space, the generation of a low level of positive airway pressure (PEEP effect), the decrease in inspiratory resistance and at the same time the increase in expiratory resistance. The present review aimed to describe the evidence surrounding the use of HFNC in stable chronic obstructive pulmonary disease patients.

Nasal highflow eliminates CO2 from lower airways

INTRODUCTION

Nasal highflow (NHF) has a growing evidence in treatment of hypoxemic respiratory failure. There are preliminary data available about use in acute and chronic type-II-respiratory failure. Unfortunately underlying mechanisms of NHF are not well understood. Increase in airway pressure seems too small to explain the observed reduction in hypercapnia. Most interesting effects are wash-out of upper airways and reduction of functional dead space. There are no data available about a wash-out of lower airways.

METHODS

We established a sheep lung model to evaluate CO₂-wash-out in lower airways. Therefore we placed measuring and insufflation catheter in maximal expanded lung. The lung was not ventilated in order to minimize influence of CO₂ rebreathing and increase in airway pressure. Airway pressure and CO₂ values were measured in lower airways and in tracheal space.

RESULTS

CO₂ was decreased by NHF in lower airways and in tracheal space. Changes in CO₂ were flow dependent. There was also an increase in airway pressure in these settings.

CONCLUSIONS

NHF is able to decrease CO₂ in lower airways in a flow-dependent manner. This effect is independent of an increase in airway pressure and CO₂-rebreathing. So wash-out is an important reason for efficiency of NHF in decreasing hypercapnia.