Nasal high flow does not improve exercise tolerance in COPD patients recovering from acute exacerbation: A randomized crossover study

The use of high-flow nasal cannula in patients with chronic obstructive pulmonary disease under exacerbation and stable phases: A systematic review and meta-analysis

BACKGROUND

High-flow nasal cannula (HFNC) has been increasingly utilized in patients with chronic obstructive pulmonary disease (COPD); however, the effects on reducing the need for intubation or reintubation remain unclear.

OBJECTIVES

We aimed to investigate whether HFNC therapy was superior to conventional oxygen therapy (COT) or noninvasive ventilation (NIV) in patients with COPD.

METHODS

A literature search was performed in electronic databases until October 1st, 2022. The primary outcome was the need for intubation/reintubation. All analyses were performed using R (version 4.0.3) and STATA SE (version 15.1).

RESULTS

When HFNC therapy was compared with NIV in patients with COPD under initial respiratory support and postextubation, no significant differences were found in the risk of intubation (RR 0.84, 95% CI 0.36 to 1.98) and reintubation (RR 1.35, 95% CI 0.73 to 2.50). Compared to NIV, HFNC therapy did not decrease the partial pressure of carbon dioxide or increase the partial pressure of oxygen to the fraction of inspired oxygen. However, HFNC therapy was associated with a lower incidence of skin breakdown (RR 0.52, 95% CI 0.39 to 0.69) and a higher comfort score (SMD 0.90, 95% CI 0.60 to 1.20) than NIV. When HFNC therapy was compared with COT during initial respiratory treatment for COPD exacerbation, a lower risk of treatment failure was found (RR 0.58, 95% CI 0.37 to 0.89). When HFNC therapy was compared with long-term oxygen therapy, quality of life (measured by SGRQ-C) was significantly improved (SMD -0.42, 95% CI -0.69 to -0.14).

CONCLUSION

HFNC therapy might be used as an alternative to NIV for COPD exacerbation with mild-moderate hypercapnia under close monitoring and is a potential domiciliary treatment for stable COPD.

Nasal high flow oxygen therapy during acute admissions or periods of worsening symptoms

PURPOSE OF REVIEW

Nasal high flow therapy (NHF) is increasingly used in acute care settings. In this review, we consider recent advances in the utilization of NHF in chronic obstructive pulmonary disease (COPD), terminal cancer and symptom management. Considerations around NHF use during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic are also discussed.

RECENT FINDINGS

NHF enables humidification and high flows to be provided together with titrated, supplemental oxygen therapy. Compared to conventional oxygen therapy, NHF improves respiratory physiology by reducing workload, enhancing muco-ciliary clearance and improving dead space washout. Some studies suggest that early use of NHF in people being cared for in the emergency department leads to lower rates of invasive ventilation and noninvasive ventilation. There is also emerging evidence for NHF use in people with COPD and chronic respiratory failure, and in palliative care. NHF is comfortable, well-tolerated and safe for use in the management of breathlessness in people with cancer. NHF can be delivered by face mask to patients with SARS-CoV-2 infection, to ease the burden on critical care resources.

SUMMARY

The evidence base for NHF is rapidly growing and offers promise in relieving troublesome symptoms and for people receiving palliative care.

Nasal High-Flow during Exercise in Patients with COPD: A Systematic Review and Meta-Analysis

Rationale Several studies have evaluated the effect of nasal high flow (NHF) to enhance exercise performance and tolerance in patients with COPD, however results are disparate. Objective The aim of this systematic review and meta-analysis was to assess the effect of NHF as an adjuvant to exercise training on functional exercise capacity in patients with COPD. Method An electronic search was carried out in the following databases: Pubmed, CENTRAL, PEDro, ScienceDirect, Web of Science, OpenGrey, ClinicalTrials.gov, European Respiratory Society and American Thoracic Society databases. Two authors independently selected relevant randomized trials (parallel group or cross-over design), extracted data, assessed the risk of bias and rated the quality of the evidence. Results Eleven studies were included, involving 408 participants (8 full papers and 3 conference abstracts). Most studies had a high risk of bias or other methodological limitations. The use of NHF during a single session increased functional exercise capacity (SMD 0.36 (95% CI 0.03 to 0.69) p=0.03, heterogeneity (I² 83 %)). When conference abstracts were included in the pooled analysis, the estimated effect did not change (p=0.006). The use of NHF throughout a pulmonary rehabilitation programme (parallel group RCTs) increased functional exercise capacity at 4 to 12 weeks compared with those who trained without NHF (SMD 0.34 (95% CI 0.00 to 0.68) p=0.05, heterogeneity (I² 18%)). Conclusion There is very low to low quality evidence that NHF improves functional exercise capacity. Patient responses to NHF therapy were highly variable and heterogeneous, with benefits ranging from clinically trivial to worthwhile. Registration (www.crd.york.ac.uk/prospero: CRD42021221550).

Recent Insights into the Measurement of Carbon Dioxide Concentrations for Clinical Practice in Respiratory Medicine

In the field of respiratory clinical practice, the importance of measuring carbon dioxide (CO2) concentrations cannot be overemphasized. Within the body, assessment of the arterial partial pressure of CO2 (PaCO2) has been the gold standard for many decades. Non-invasive assessments are usually predicated on the measurement of CO2 concentrations in the air, usually using an infrared analyzer, and these data are clearly important regarding climate changes as well as regulations of air quality in buildings to ascertain adequate ventilation. Measurements of CO2 production with oxygen consumption yield important indices such as the respiratory quotient and estimates of energy expenditure, which may be used for further investigation in the various fields of metabolism, obesity, sleep disorders, and lifestyle-related issues. Measures of PaCO2 are nowadays performed using the Severinghaus electrode in arterial blood or in arterialized capillary blood, while the same electrode system has been modified to enable relatively accurate non-invasive monitoring of the transcutaneous partial pressure of CO2 (PtcCO2). PtcCO2 monitoring during sleep can be helpful for evaluating sleep apnea syndrome, particularly in children. End-tidal PCO2 is inferior to PtcCO2 as far as accuracy, but it provides breath-by-breath estimates of respiratory gas exchange, while PtcCO2 reflects temporal trends in alveolar ventilation. The frequency of monitoring end-tidal PCO2 has markedly increased in light of its multiple applications (e.g., verify endotracheal intubation, anesthesia or mechanical ventilation, exercise testing, respiratory patterning during sleep, etc.).

Effect of high-flow nasal cannula oxygen therapy in patients with chronic obstructive pulmonary disease: A meta-analysis

BACKGROUND

High-flow nasal cannula oxygen therapy reduces the arterial partial pressure of carbon dioxide and acute exacerbation but does not increase exercise capacity or decrease hospitalisation or mortality. The study aimed to test the hypothesis that in chronic obstructive pulmonary disease patients, the use of high-flow nasal cannula decreases arterial partial pressure of carbon dioxide and increases the partial pressure of oxygen and 6-min walking distance.

METHODS

PubMed, Embase and the Cochrane library were searched for eligible studies published from database inception to November 2020 (Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist). The primary outcomes were partial pressure of carbon dioxide and partial pressure of oxygen, and the secondary outcomes were transcutaneous partial pressure of carbon dioxide and 6-min walking distance.

RESULTS

Nine studies (680 patients) were included. high-flow nasal cannula did not decrease partial pressure of carbon dioxide compared with the control interventions (mean difference = -0.81, 95% confidence interval: -2.68 to 1.06, p = .395; I²  = 42.9%, p_{heterogeneity}  = .105). high-flow nasal cannula decreased partial pressure of carbon dioxide compared with long-term oxygen therapy (mean difference = -3.25, 95% confidence interval: -5.65 to -0.85, p = .008; I²  = 0%, p_{heterogeneity}   = .375); no difference was observed for the control modalities. high-flow nasal cannula resulted in better partial pressure of carbon dioxide compared with control interventions in hypoxemic patients (mean difference = -2.59, 95% confidence interval: -4.82 to -0.35, p = .023; I²  = 32.5%, p_{heterogeneity}  = .224), but not in other types of patients. high-flow nasal cannula did not increase partial pressure of oxygen compared with the control interventions (mean difference = 1.17, 95% confidence interval: -1.50 to 3.83, p = .390; I²  = 0%, p_{heterogeneity}  = .660). high-flow nasal cannula decreased transcutaneous carbon dioxide tension (transcutaneous partial pressure of carbon dioxide) compared with the control interventions (mean difference = 2.37, 95% confidence interval: 0.07-4.68, p = .044; I²  = 8.7%, p_{heterogeneity}   = .295). high-flow nasal cannula increased 6-min walking distance compared with the control interventions (mean difference = 18.22, 95% confidence interval: 0.86-,35.57, p = .040; I²  = 0%, p_{heterogeneity}  = .918). The sensitivity analyses showed that the results were robust.

CONCLUSIONS

High-flow nasal cannula did not significantly decrease partial pressure of carbon dioxide or increase partial pressure of oxygen in chronic obstructive pulmonary disease patients, which is different from the previous meta-analysis, but it decreases transcutaneous partial pressure of carbon dioxide and increased 6-min walking distance.

RELEVANCE TO CLINICAL PRACTICE

This meta-analysis shows that in patients with chronic obstructive pulmonary disease, high-flow nasal cannula improves both transcutaneous partial pressure of carbon dioxide and 6-min walking distance, suggesting the high-flow nasal cannula has benefits in the management of chronic obstructive pulmonary disease. Considering that the literature suggests no impact of high-flow nasal cannula on hospitalisation and mortality, the benefits of high-flow nasal cannula might be limited to the patients who survive the chronic obstructive pulmonary disease events. Still, the global impact of high-flow nasal cannula on the quality of life of patients with chronic obstructive pulmonary disease should be examined.

Effects of high flow nasal cannula on exercise endurance in patients with chronic obstructive pulmonary disease

BACKGROUND

Ventilation limitation has a significant adverse effects on cardiovascular function and tissue oxygenation during exercise in patients with chronic obstructive pulmonary disease (COPD). High flow nasal cannula (HFNC) improve ventilation by washing out the anatomical dead space and providing oxygen at constant concentration. This study aimed to examine the effects of HFNC on the exercise performance and hemodynamic status in COPD patients.

METHODS

Fifteen patients with COPD performed two constant load exercise tests (CLET) at the 70% of maximum workload achieved at a previous incremental exercise test on arm ergometer. The CLET were performed with HFNC and with nasal cannula (NC) in random order. The hemodynamics parameters of subjects during exercises were measured by a bioelectrical impedance device. The tissue oxygenation status (oxygenated hemoglobin, deoxygenated hemoglobin (hHb), total hemoglobin) was measured by a near infrared spectrophotometer.

RESULTS

The exercise duration was longer for HFNC test than NC test (962.9 ± 281.7 s, vs 823.9 ± 184.9 s, p < 0.05). At the end of CLET, the PetCO2 was lower for HFNC than NC (29.3 ± 5.1 mmHg vs 32.1 ± 5.5 mmHg, p < 0.05). There was no difference in cardiac output (NC: 7.5 ± 1.8 vs HFNC: 7.4 ± 3.0 L,p > 0.05), stroke volume (NC:73.5 ± 21.0 vs HFNC 67.5 ± 16.3 ml, p > 0.05). The changes of hHb in muscle tissues was significantly lower in HFNC test than that in NC test (p < 0.05).

CONCLUSION

HFNC resulted in a significant decrease in CO2 production and increase in exercise duration. The application of HFNC may improve the efficiency of exercise training by allowing patients to sustain exercise for longer time.

Effect of High-Flow Oxygen on Exercise Performance in COPD Patients. Randomized Trial

Background: High-flow oxygen therapy (HFOT) provides oxygen-enriched, humidified, and heated air at high flow rates via nasal cannula. It could be an alternative to low-flow oxygen therapy (LFOT) which is commonly used by patients with chronic obstructive pulmonary disease (COPD) during exercise training.

Research Question: We evaluated the hypothesis that HFOT improves exercise endurance in COPD patients compared to LFOT.

Methods: Patients with stable COPD, FEV₁ 40–80% predicted, resting pulse oximetry (SpO₂) ≥92%, performed two constant-load cycling exercise tests to exhaustion at 75% of maximal work rate on two different days, using LFOT (3 L/min) and HFOT (60 L/min, FiO₂ 0.45) in randomized order according to a crossover design. Primary outcome was exercise endurance time, further outcomes were SpO₂, breath rate and dyspnea.

Results: In 79 randomized patients, mean ± SD age 58 ± 9 y, FEV₁ 63 ± 9% predicted, GOLD grades 2-3, resting PaO₂ 9.4 ± 1.0 kPa, intention-to-treat analysis revealed an endurance time of 688 ± 463 s with LFOT and 773 ± 471 s with HFOT, mean difference 85 s (95% CI: 7 to 164, P = 0.034), relative increase of 13% (95% CI: 1 to 28). At isotime, patients had lower respiratory rate and higher SpO₂ with HFOT. At end-exercise, SpO₂ was higher by 2% (95% CI: 2 to 2), and Borg CR10 dyspnea scores were lower by 0.8 points (95% CI: 0.3 to 1.2) compared to LFOT.

Interpretation: In mildly hypoxemic patients with COPD, HFOT improved endurance time in association with higher arterial oxygen saturation, reduced respiratory rate and less dyspnea compared to LFOT. Therefore, HFOT is promising for enhancing exercise performance in COPD.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT03955770.

High-flow therapy: physiological effects and clinical applications

Humidified high-flow therapy (HFT) is a noninvasive respiratory therapy, typically delivered through a nasal cannula interface, which delivers a stable fraction of inspired oxygen (F_IO2) at flow rates of up to 60 L·min⁻¹. It is well-tolerated, simple to set up and ideally applied at 37°C to permit optimal humidification of inspired gas. Flow rate and F_IO2 should be selected based on patients' inspiratory effort and severity of hypoxaemia. HFT yields beneficial physiological effects, including improved mucociliary clearance, enhanced dead space washout and optimisation of pulmonary mechanics. Robust evidence supports its application in the critical care setting (treatment of acute hypoxaemic respiratory failure and prevention of post-extubation respiratory failure) and emerging data supports HFT use during bronchoscopy, intubation and breaks from noninvasive ventilation or continuous positive airway pressure. There are limited data on HFT use in patients with hypercapnic respiratory failure, as an adjunct to pulmonary rehabilitation and in the palliative care setting, and further research is needed to validate the findings of small studies. The COVID-19 pandemic raises questions regarding HFT efficacy in COVID-19-related hypoxaemic respiratory failure and concerns regarding aerosolisation of respiratory droplets. Clinical trials are ongoing and healthcare professionals should implement strict precautions to mitigate the risk of nosocomial transmission.

Humidified high-flow therapy is a well-tolerated method of delivering a stable F_IO2 at flow rates up to 60 L/min. It improves secretion clearance, dead space washout and pulmonary mechanics and is an effective treatment in hypoxaemic respiratory failurehttps://bit.ly/35Hvjrj

High-flow nasal cannula for acute exacerbation of chronic obstructive pulmonary disease: A systematic review and meta-analysis

BACKGROUND

The evidence for the safety of high-flow nasal cannula (HFNC) in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients is conflicting.

OBJECTIVES

To evaluate the intubation and mortality risks of HFNC compared to non-invasive ventilation (NIV) and conventional oxygen therapy (COT) for AECOPD patients.

METHODS

A search of electronic databases was performed. Studies that used HFNC to treat AECOPD patients were identified.

RESULTS

Seven RCTs and one observational study were included. There were no differences in intubation risk (risk ratio (RR) 0.94, 95% confidence interval (CI) 0.49 to 1.78, p = 0.84, very low certainty) and mortality risk (RR 0.91, 95% CI 0.46 to 1.79, p = 0.77, very low certainty) for HFNC compared with NIV. No data were available for intubation or mortality risk for HFNC compared with COT.

CONCLUSION

For AECOPD patients, low-quality evidence indicates that HFNC does not increase intubation and mortality risks compared to NIV.

Efficiency of High-Flow Nasal Cannula on Pulmonary Rehabilitation in COPD Patients: A Meta-Analysis

Introduction

The clinical benefit of high-flow nasal cannula (HFNC) on factors related to pulmonary rehabilitation in chronic obstructive pulmonary disease (COPD) patients remains unclear. This meta-analysis aimed at synthesizing the available evidence on the efficacy of HFNC on exercise capacity, lung function, and other factors related to pulmonary rehabilitation in COPD patients.

Methods

Electronic databases (MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Web of Science) were searched for randomized trials comparing with conventional oxygen therapy (COT) or noninvasive ventilation (NIV). Primary outcomes were respiratory rate, FEV1, tidal volume, oxygen partial pressure, total score of St. George's respiratory questionnaire, 6-minute walk test, and exercise endurance time.

Results

Ten trials met the criteria for inclusion. Combined data from six studies showed that HFNC showed a lower respiratory rate in COPD patients [mean difference -1.27 (95% CI: -1.65–(-0.89)]. Combined data from three studies showed a lower forced expiratory volume in one second (FEV1) in the group of HFNC. No difference in tidal volume was showed between the HFNC and control groups in COPD patients. No significant oxygen improvement between the HFNC groups and control groups. The total score of St. George's respiratory questionnaire was improved by the subgroup analysis of HFNC versus COT but no NIV. Two multicenter RCTs showed the six-minute walk test, and statistical results showed that the length of the six-minute walk capacity was increased after usage of HFNC compared to the control group [mean difference -8.65 (95% CI: -9.12–(-8.19)]. No increase of exercise capacity after usage of HFNC (mean difference -12.65).

Conclusion

In the first meta-analysis of the area, the current evidence did not show so much positive effect on tidal volume or oxygen improvement in COPD patients. Length of the six-minute walk capacity was increased after using HFNC, while other pulmonary rehabilitation parameters, namely, the score of St. George's respiratory questionnaire and exercise capacity show no increase in the group of HFNC. The variance in the quality of the evidence included in this meta-analysis highlights the need for this evidence to be followed up with further high-quality and more randomized trials.

High flow nasal therapy during early pulmonary rehabilitation in patients with acute severe exacerbation of COPD: beneficial or illusory?

In study “Effect of high-flow nasal therapy during early pulmonary rehabilitation in patients with severe AECOPD: a randomized controlled study” by Tung et al., authors concluded HFNT utilization led to enhanced exercise tolerance and a reduction of systemic inflammation. Nevertheless, some points requires additional discussion, the conclusion of the trial seems overstated. The baseline differences between groups induces substantial modifications in the conclusions of this trial. HFNT does not seem to add any benefit on exercise tolerance or systemic inflammation, nor on pulmonary function. The only difference that remained significant in homogenous statistical significance is dyspnea on the mMRC scale but clinical significance is highly questionable.

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.