The Effects of High-Flow vs Low-Flow Oxygen on Exercise in Advanced Obstructive Airways Disease

Home-based respiratory support

This review provides an overview of home-based respiratory support modalities for patients with chronic lung diseases. It discusses the increasing use of long-term high-flow nasal cannula (LT-HFNC) and long-term non-invasive ventilation (LT-NIV) and their potential to enhance patient quality of life. This review addresses various types of respiratory failure and their respective treatments, emphasising the significance of monitoring and telemedicine in home care. This comprehensive review underscores the clinical relevance of these interventions in the management of chronic lung diseases.

Monitoring Changes in Oxygen Muscle during Exercise with High-Flow Nasal Cannula Using Wearable NIRS Biosensors

Exercise increases the cost of breathing (COB) due to increased lung ventilation (V˙E), inducing respiratory muscles deoxygenation (∇SmO2), while the increase in workload implies ∇SmO2 in locomotor muscles. This phenomenon has been proposed as a leading cause of exercise intolerance, especially in clinical contexts. The use of high-flow nasal cannula (HFNC) during exercise routines in rehabilitation programs has gained significant interest because it is proposed as a therapeutic intervention for reducing symptoms associated with exercise intolerance, such as fatigue and dyspnea, assuming that HFNC could reduce exercise-induced ∇SmO2. SmO2 can be detected using optical wearable devices provided by near-infrared spectroscopy (NIRS) technology, which measures the changes in the amount of oxygen bound to chromophores (e.g., hemoglobin, myoglobin, cytochrome oxidase) at the target tissue level. We tested in a study with a cross-over design whether the muscular desaturation of m.vastus lateralis and m.intercostales during a high-intensity constant-load exercise can be reduced when it was supported with HFNC in non-physically active adults. Eighteen participants (nine women; age: 22 ± 2 years, weight: 65.1 ± 11.2 kg, height: 173.0 ± 5.8 cm, BMI: 21.6 ± 2.8 kg·m-2) were evaluated in a cycle ergometer (15 min, 70% maximum watts achieved in ergospirometry (V˙O2-peak)) breathing spontaneously (control, CTRL) or with HFNC support (HFNC; 50 L·min-1, fiO2: 21%, 30 °C), separated by seven days in randomized order. Two-way ANOVA tests analyzed the ∇SmO2 (m.intercostales and m.vastus lateralis), and changes in V˙E and ∇SmO2·V˙E-1. Dyspnea, leg fatigue, and effort level (RPE) were compared between trials by the Wilcoxon matched-paired signed rank test. We found that the interaction of factors (trial × exercise-time) was significant in ∇SmO2-m.intercostales, V˙E, and (∇SmO2-m.intercostales)/V˙E (p < 0.05, all) but not in ∇SmO2-m.vastus lateralis. ∇SmO2-m.intercostales was more pronounced in CTRL during exercise since 5' (p < 0.05). Hyperventilation was higher in CTRL since 10' (p < 0.05). The ∇SmO2·V˙E-1 decreased during exercise, being lowest in CTRL since 5'. Lower dyspnea was reported in HFNC, with no differences in leg fatigue and RPE. We concluded that wearable optical biosensors documented the beneficial effect of HFNC in COB due to lower respiratory ∇SmO2 induced by exercise. We suggest incorporating NIRS devices in rehabilitation programs to monitor physiological changes that can support the clinical impact of the therapeutic intervention implemented.

Efficacy of different respiratory supports to prevent hypoxia during flexible bronchoscopy in patients of COPD: a triple-arm, randomised controlled trial

BACKGROUND

Patients with chronic-obstructive-pulmonary-disease (COPD) undergo bronchoscopy for various reasons, and are at relatively higher risk of complications. This study evaluated the efficacy of non-invasive ventilation (NIV) and high-flow-oxygen-therapy (HFOT) compared with conventional-oxygen-therapy (COT) in patients with COPD undergoing bronchoscopy, to prevent hypoxia.

METHODS

It was a triple-arm, open-label, randomised controlled trial. Ninety patients with COPD were randomly assigned into three intervention arms in 1:1:1 ratio. The incidence of hypoxia, lowest recorded oxygen saturation measured by plethysmography (SpO2), ECG, patient vitals and comfort levels were assessed.

RESULTS

Mean age of the study population was 61.71±7.5 years. Out of 90 cases enrolled, 51, 34 and 5 were moderate, severe and very-severe COPD, respectively, as per GOLD (Global Initiative for Chronic Obstructive Lung Disease) classification. Rest of the baseline characteristics were similar. SpO2 during flexible bronchoscopy (FB) was lowest in COT group (COT: 87.03±5.7% vs HFOT: 95.57±5.0% vs NIV: 97.40±1.6%, p<0.001). Secondary objectives were similar except respiratory-rate (breaths-per-minute) which was highest in COT group (COT: 20.23±3.1 vs HFOT: 18.57±4.1 vs NIV: 16.80±1.9, p<0.001). Whereas post FB partial of oxygen in arterial blood was highest in NIV group (NIV: 84.27±21.6 mm Hg vs HFOT: 69.03±13.6 mm Hg vs COT: 69.30±11.9 mm Hg, p<0.001). Post FB partial pressure of carbon dioxide in arterial blood was similar in the three arms. Operator's ease-of-performing-procedure was least in the NIV group as assessed with Visual Analogue Scale (p<0.01). A higher number of NIV group participants reported nasal pain as compared with the other two arms (p<0.01).

CONCLUSION

NIV and HFOT are superior to COT in preventing hypoxia during bronchoscopy, but NIV is associated with poor patient-tolerance and inferior operator's ease of doing procedure.

TRIAL REGISTRATION NUMBER

CTRI/2021/03/032190.

Effects of High-Flow Nasal Cannula on Right Heart Dysfunction in Patients with Acute-on-Chronic Respiratory Failure and Pulmonary Hypertension

High-flow nasal cannula (HFNC) has several benefits in patients affected by different forms of acute respiratory failure, based on its own mechanisms. We postulated that HFNC may have some advantages over conventional oxygen therapy (COT) on the heart function in patients with acute-on-chronic respiratory failure with concomitant pulmonary hypertension (PH). We therefore designed this retrospective observational study to assess if HFNC improves the right and left ventricle functions and morphologies, arterial blood gases (ABGs), and patients' dyspnea, compared to COT. We enrolled 17 hospitalized patients receiving HFNC, matched with 17 patients receiving COT. Echocardiographic evaluation was performed at the time of admission (baseline) and 10 days after (T10). HFNC showed significant improvements in right ventricular morphology and function, and a reduction in sPAP. However, there were no significant changes in the left heart measurements with HFNC application. Conversely, COT did not lead to any modifications in echocardiographic measurements. In both groups, oxygenation significantly improved from baseline to T10 (in the HFNC group, from 155 ± 47 to 204 ± 61 mmHg while in the COT group, from 157 ± 27 to 207 ± 27 mmHg; p < 0.0001 for both comparisons). In conclusion, these data suggest an improvement of oxygenation with both treatments; however, only HFNC was able to improve the right ventricular morphology and function after 10 days from the beginning of treatment in a small cohort of patients with acute-on-chronic respiratory failure with PH.

Home High-Flow Therapy in Patients with Chronic Respiratory Diseases: Physiological Rationale and Clinical Results

High-flow therapy (HFT) is the administration of gas flows above 15 L/min. It is a non-invasive respiratory support that delivers heated (up to 38 °C), humidified (100% Relative Humidity, RH; 44 mg H2O/L Absolute Humidity, AH), oxygen-enriched air when necessary, through a nasal cannula or a tracheostomy interface. Over the last few years, the use of HFT in critically ill hypoxemic adults has increased. Although the clinical benefit of home high-flow therapy (HHFT) remains unclear, some research findings would support the use of HHFT in chronic respiratory diseases. The aim of this review is to describe the HFT physiological principles and summarize the published clinical findings. Finally, we will discuss the differences between hospital and home implementation, as well as the various devices available for HHFT application.

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.

The Danish respiratory society guideline for long-term high flow nasal cannula treatment, with or without supplementary oxygen

Introduction

Long-term High Flow Nasal Cannula (LT-HFNC), defined as High Flow Nasal Cannula treatment provided to patients with chronic pulmonary conditions during stable phases, has emerged as a home treatment in different categories of patients with chronic lung diseases in recent years.

Methods

This paper summarizes the physiological effects of LT-HFNC and evaluates the clinical knowledge to date about treatment in patients with chronic obstructive lung disease, interstitial lung disease and bronchiectasis. The guideline is translated and summarized in this paper and presented unabridged as an appendix to the paper.

Results

The paper describes the working process behind the Danish Respiratory Society's National guideline for treatment of stable disease, which has been written to support clinicians in both evidence-based decision making and practical issues concerning the treatment.

Domiciliary High-Flow Nasal Therapy in Primary Ciliary Dyskinesia

We report the case of an adolescent with severe primary ciliary dyskinesia (PCD) phenotype associated with a rare genotype. His clinical condition deteriorated, with daily cough and breathlessness, hypoxemia, and lung function decline. Despite being started on home noninvasive ventilation (NIV), the symptoms progressed to dyspnea at rest and thoracic pain. High-flow nasal cannula (HFNC) was started during the daytime as an adjuvant to NIV, and he was started on regular oral opioids for pain and dyspnea control. There was a clear improvement in comfort and dyspnea and breathing work relief. Additionally, better exercise tolerance was also noted. He is currently on the lung transplant waiting list. We aim to emphasize the benefits of HFNC as an add-on therapy for the management of chronic breathlessness since our patient experienced an improvement in breathing and exercise tolerance. However, there is a paucity of studies regarding domiciliary HFNC, particularly in pediatric age. Therefore, further studies are needed to achieve optimal and personalized care. Close monitoring and frequent reassessment in a specialized center are key to adequate management.

Recent advances in the use of high flow nasal oxygen therapies

High flow nasal oxygen is a relatively new option for treating patients with respiratory failure, which decreases work of breathing, improves tidal volume, and modestly increases positive end expiratory pressure. Despite well-described physiologic benefits, the clinical impact of high flow nasal oxygen is still under investigation. In this article, we review the most recent findings on the clinical efficacy of high flow nasal oxygen in Type I, II, III, and IV respiratory failure within adult and pediatric patients. Additionally, we discuss studies across clinical settings, including emergency departments, intensive care units, outpatient, and procedural settings.

High-flow nasal cannula for respiratory failure in adult patients

The high-flow nasal cannula (HFNC) has been recently used in several clinical settings for oxygenation in adults. In particular, the advantages of HFNC compared with low-flow oxygen systems or non-invasive ventilation include enhanced comfort, increased humidification of secretions to facilitate expectoration, washout of nasopharyngeal dead space to improve the efficiency of ventilation, provision of a small positive end-inspiratory pressure effect, and fixed and rapid delivery of an accurate fraction of inspired oxygen (FiO₂) by minimizing the entrainment of room air. HFNC has been successfully used in critically ill patients with several conditions, such as hypoxemic respiratory failure, hypercapneic respiratory failure (exacerbation of chronic obstructive lung disease), post-extubation respiratory failure, pre-intubation oxygenation, and others. However, the indications are not absolute, and much of the proven benefit remains subjective and physiologic. This review discusses the practical application and clinical uses of HFNC in adults, including its unique respiratory physiologic effects, device settings, and clinical indications.

Treatment of acute respiratory failure: high-flow nasal cannula

Background: High-flow nasal cannulas (HFNCs) have recently been used for several conditions, such as hypoxemic respiratory failure, hypercapnic respiratory failure, post-extubation respiratory failure, and preintubation oxygenation, in critically ill patients.Current Concepts: The advantages of HFNC compared with those of low-flow oxygen systems or noninvasive ventilation include enhanced comfort, increased humidification of secretions to facilitate expectoration, washout of the nasopharyngeal dead space to improve ventilation efficiency, provisioning for low positive end-inspiratory pressure effect, and fixed and rapid delivery of accurate fraction of inspired oxygen by minimizing the entrainment of room air. However, the indications are not absolute, with much of the proven benefit being subjective and physiologic.Discussion and Conclusion: The goal of this review is to discuss the practical application and clinical uses of HFNCs in patients with acute respiratory failure, highlighting its unique respiratory and physiologic effects, device settings, and clinical indications.

High Flow Nasal Cannula in the Pediatric Intensive Care Unit

INTRODUCTION

The use of high flow nasal cannula (HFNC) has become widely used in pediatric intensive care units (PICUs) throughout the world. The rapid adoption has outpaced the number of studies evaluating the safety and efficacy in a variety of pediatric diseases/conditions.

AREAS COVERED

This scoping review begins with the definition and mechanisms of action of HFNC and then follows with a review of the literature focused on studies performed on critically ill children cared for in the PICU. The Pubmed database was searched with a pediatric filter from the time period 2000 to 2021.

EXPERT OPINION

The rapid adoption of HFNC in PICUs has largely been driven by changes in institutional practices and small observational studies. There is a lack of adequately powered studies evaluating patient-centered outcomes, such as intubation rates, mortality, PICU and hospital length of stay. Given the wide variability in flow rates and clinical indications, more research is needed to better define effective flow rates for different disease states as well as markers of treatment success and failure. One particular entity that is poorly studied is the use of HFNC in those at risk for developing pediatric acute respiratory distress syndrome (PARDS).

The effect of domiciliary high flow nasal cannula treatment on dyspnea and walking distance in patients with interstitial lung disease - A pilot study

INTRODUCTION

Interstitial Lung Diseases (ILD) affect the lung parenchyma and are often complicated by respiratory failure (RF) and impaired physical activity. High Flow Nasal Cannula (HFNC) has proved effective in other disease entities with RF. The aim of this study is to investigate the effect of domiciliary HFNC in ILD on dyspnea and walking distance.

METHODS

A 6 weeks cross-over study with domiciliary HFNC-treatment/6 weeks' observation in ILD-patients requiring ambulatory oxygen therapy or with newly prescribed (within 12 months) long term oxygen therapy. Patients were advised to use HFNC 8 h/day, recommended night-time use. Body phletysmography; 6-min walk test (6MWT) including BORG-score, oxygen saturation (SO2) at start, minimum SO2 and time to recovery after 6MWT; arterial blood gasses; modified Medical Research Council (mMRC)-score; quality of life, by the St George Respiratory Questionnaire (SGRQ) and QoS, by the Richards-Campbell Sleep Questionnaire (RCSQ) were investigated at baseline; six weeks and 12 weeks.

RESULTS

10 patients were included; one later withdrew consent. Patients used HFNC between 8-<1 h/day. There were no differences in lung function; blood gasses; SGRQ or RCSQ over the observational period). Walking distance improved significantly (393-441 m p = 0.049) as did time to recovery (3.4-2-2 min, p = 0.001). When correcting for HFNC use (hours/day) significant improvement was also seen in mMRC-score (p = 0.035) and minimum saturation during 6MWT (p = 0.01).

CONCLUSION

Despite a very heterogenous group and no effect on quality of life and -sleep, the study indicates an improvement in dyspnea and physical ability of HFNC in ILD patients.

High flow nasal cannula versus standard low flow nasal oxygen during flexible bronchoscopy in children: A randomized controlled trial

BACKGROUND

Hypoxemia is the most frequent complication of fiberoptic bronchoscopy (FB) in children. Guidelines recommend oxygen supplementation and conventional nasal prongs (NC) are used for this purpose. The aim of this study was to evaluate if the use of high-flow nasal cannula therapy (HFNC) in children undergoing FB result in a lower incidence of hypoxemia than standard oxygen administration.

METHODS

Patients aged 1 month-16 years undergoing elective FB were included in a prospective randomized controlled, nonblinded, single-center clinical trial and randomly assigned to receive oxygen via NC or HFNC. Patients' baseline characteristics were recorded pre-bronchoscopy. The primary outcome was oxygen desaturation during the procedure defined as saturation less than 94%.

RESULTS

An intention to treat analysis for 53 patients receiving NC and 51 receiving HFNC, showed HFNC patients were less likely to have hypoxemia than were NC patients (p = .011), with an absolute risk reduction of 0.27 (95% confidence interval [CI]: 0.08-0.45) and a number needed to treat of 3.75 (95% CI: 2.22-12.04). Moderate hypoxemia (SpO₂  ≥ 90% and <94%, and <60 s) was observed significantly less often with HFNC than with NC (p = .012). Severe hypoxemia (SpO₂  < 90% and >30 s) was not different between groups. Patients undergoing bronchoalveolar lavage (BAL) presented fewer desaturations with HFNC (p = .0003).

CONCLUSIONS

HFNC offers optimized oxygenation during elective FB with a significant reduction in desaturations and can be considered for oxygen administration, especially when BAL is performed.

The effect of heated humidified nasal high flow oxygen supply on exercise tolerance in patients with interstitial lung disease: A pilot study

BACKGROUND AND OBJECTIVES

Patients with interstitial lung disease (ILD) experience early symptoms of dyspnoea and leg fatigue during exercise together with severe and rapid oxygen desaturation. Heated and humidified nasal high flow oxygen (NHF) has been proven to enhance exercise endurance and physiological parameters in COPD patients. This study aims to evaluate the effect of NHF on exercise tolerance in ILD patients.

METHODS

Twenty-five patients (10 female) with severe ILD performed three constant-load (70% maximal workload) cycling tests to exhaustion under different breathing conditions: room air, oxygen supplementation (4 L min^-1 O₂) and NHF (inspiratory O₂ fraction 0.5, 30-50 L min^-1, heated 34 °C and humidified).

RESULTS

Endurance time was significantly longer with NHF (618 ± 297 s) compared to O₂ (369 ± 217 s, p < 0.001) and room air (171 ± 76 s, p < 0.001). Kinetics of oxygen desaturation, chronotropic response, dyspnoea and leg fatigue sensations were delayed with NHF. At exhaustion with NHF, compared to the two other conditions, oxygen desaturation was less severe while heart rate, dyspnoea and leg fatigue were similar.

CONCLUSION

NHF significantly improved endurance time, physiological parameters and sensations during exercise in severe ILD patients. NHF may be useful to improve functional capacities and facilitate pulmonary rehabilitation in ILD.

High-Flow Nasal Cannula Therapy for Exertional Dyspnea in Patients with Cancer: A Pilot Randomized Clinical Trial

BACKGROUND

Exertional dyspnea is common in patients with cancer and limits their function. The impact of high-flow nasal cannula on exertional dyspnea in nonhypoxemic patients is unclear. In this double-blind, parallel-group, randomized trial, we assessed the effect of flow rate (high vs. low) and gas (oxygen vs. air) on exertional dyspnea in nonhypoxemic patients with cancer.

PATIENTS AND METHODS

Patients with cancer with oxygen saturation >90% at rest and exertion completed incremental and constant work (80% maximal) cycle ergometry while breathing low-flow air at 2 L/minute. They were then randomized to receive high-flow oxygen, high-flow air, low-flow oxygen, or low-flow air while performing symptom-limited endurance cycle ergometry at 80% maximal. The primary outcome was modified 0-10 Borg dyspnea intensity scale at isotime. Secondary outcomes included dyspnea unpleasantness, exercise time, and adverse events.

RESULTS

Seventy-four patients were enrolled, and 44 completed the study (mean age 63; 41% female). Compared with low-flow air at baseline, dyspnea intensity was significantly lower at isotime with high-flow oxygen (mean change, -1.1; 95% confidence interval [CI], -2.1, -0.12) and low-flow oxygen (-1.83; 95% CI, -2.7, -0.9), but not high-flow air (-0.2; 95% CI, -0.97, 0.6) or low-flow air (-0.5; 95% CI, -1.3, 0.4). Compared with low-flow air, high-flow oxygen also resulted in significantly longer exercise time (difference + 2.5 minutes, p = .009), but not low-flow oxygen (+0.39 minutes, p = .65) or high-flow air (+0.63 minutes, p = .48). The interventions were well tolerated without significant adverse effects.

CONCLUSION

Our preliminary findings support that high-flow oxygen improved both exertional dyspnea and exercise duration in nonhypoxemic patients with cancer. (ClinicalTrials.gov ID: NCT02357134).

IMPLICATIONS FOR PRACTICE

In this four-arm, double-blind, randomized clinical trial examining the role of high-flow nasal cannula on exertional dyspnea in patients with cancer without hypoxemia, high-flow oxygen, but not high-flow air, resulted in significantly lower dyspnea scores and longer exercise time. High-flow oxygen delivered by high-flow nasal cannula devices may improve clinically relevant outcomes even in patients without hypoxemia.

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.

Tolerability and Safety of High-Flow Nasal Therapy in Patients Hospitalized with an Exacerbation of COPD

BACKGROUND

The effect of high-flow nasal therapy (HFNT) in individuals with an exacerbation of chronic obstructive pulmonary disease (COPD) and hypercapnia is not well studied. We assessed patient tolerance and impact of air-gas therapy delivered by humidified HFNT (20-35 L/min) on gas exchange in hypercapnic COPD patients during hospitalization for COPD exacerbation. We hypothesized that HFNT use would be safe and well tolerated in individuals hospitalized for COPD exacerbation regardless of the degree of hypercapnia.

METHODS

Patients hospitalized for a COPD exacerbation were included if they were hypercapnic (arterial partial pressure of carbon dioxide [PaCO2] > 45 mmHg), ≥ 10 pack-year history, and agreed to treatment with HFNT, along with daily arterial blood gas (ABG) samples and bedside spirometry. They were placed on a HFNT system following admission for at least 3 days with an air-gas blend to maintain a flow rate between 20-35 L/min and fraction of inspired oxygen (FiO2) titrated to keep oxygen saturation (SaO2) values > 90%. Patient tolerance of HFNT and evidence of clinical deterioration as defined by worsening hypoxia or hypercapnia was the primary endpoint.

RESULTS

Ten consecutive patients participated in the study. The patients had frequent prior exacerbations, were hypercapnic, dyspneic, and gas trapped. Participants received an air-gas flow rate (median [interquartile range (IQR)] 25 (IQR 20-30) L/min and FiO2 of 30 (IQR 30-30) %. There was no increase in PaCO2- levels (p = 0.26) or dyspnea (Borg scale, p= 0.52) while using HFNT. No patient discontinued HFNT, had further decompensation, required non-invasive ventilation or intubation during the study period.

CONCLUSION

In a pilot study, patients experiencing a severe COPD exacerbation were able to tolerate continuous HFNT safely regardless of degree of hypercapnia.

Is Structured Exercise Performed with Supplemental Oxygen a Promising Method of Personalized Medicine in the Therapy of Chronic Diseases?

Aim: This systematic review aimed to explore the literature to identify in which types of chronic diseases exercise with supplemental oxygen has previously been utilized and whether this type of personalized therapy leads to superior effects in physical fitness and well-being. Methods: Databases (PubMed/MEDLINE, CINHAL, EMBASE, Web of knowledge and Cochrane Library) were searched in accordance with PRISMA. Eligibility criteria included adult patients diagnosed with any type of chronic diseases engaging in supervised exercise training with supplemental oxygen compared to normoxia. A random-effects model was used to pool effect sizes by standardized mean differences (SMD). Results: Out of the identified 4038 studies, 12 articles were eligible. Eleven studies were conducted in chronic obstructive pulmonary disease (COPD), while one study included coronary artery disease (CAD) patients. No statistical differences were observed for markers of physical fitness and patient-reported outcomes on well-being between the two training conditions (SMD −0.10; 95% CI −0.27, 0.08; p = 0.26). Conclusions: We found that chronic exercise with supplemental oxygen has mainly been utilized for COPD patients. Moreover, no superior long-term adaptations on physical fitness, functional capacity or patient-reported well-being were found, questioning the role of this method as a personalized medicine approach. Prospero registration: CRD42018104649.

High-flow nasal cannula oxygen therapy in acute hypoxemic respiratory failure in 22 dogs requiring oxygen support escalation

OBJECTIVE

To determine the effect of high-flow nasal cannula (HFNC) oxygen therapy on cardiorespiratory variables and outcome in dogs with acute hypoxemic respiratory failure.

DESIGN

Prospective, sequential clinical trial.

SETTING

University veterinary teaching hospital.

ANIMALS

Twenty-two client-owned dogs that failed to respond to traditional oxygen support.

INTERVENTIONS

Initiation of HFNC therapy after traditional oxygen supplementation failed to increase Spo₂ > 96% and Pao₂ > 75 mm Hg or improve respiratory rate/effort.

MEASUREMENTS AND MAIN RESULTS

Physiological variables, blood gas analyses, and dyspnea/sedation/tolerance scores were collected prior to HFNC initiation (on traditional oxygen support [time 0 or T0]), and subsequently during HFNC oxygen administration at time 30 minutes, 60 minutes, and 7 ± 1 hours. Relative to T0, use of HFNC resulted in a decreased respiratory rate at 1 hour (P = 0.022) and 7 hours (P = 0.012), a decrease in dyspnea score at all times (P < 0.01), and an increase in Spo₂ at all times (P < 0.01). There was no difference in arterial/venous Pco₂ relative to T0, although Paco₂ was correlated with flow rate. Based on respiratory assessment, 60% of dogs responded to HFNC use by 30 minutes, and 45% ultimately responded to HFNC use and survived. No clinical air-leak syndromes were observed.

CONCLUSIONS

HFNC use improved oxygenation and work of breathing relative to traditional oxygen therapies, without impairing ventilation. HFNC use appears to be a beneficial oxygen support modality to bridge the gap between standard oxygen supplementation and mechanical ventilation.

High-flow nasal cannula oxygen therapy as an emerging option for respiratory failure: the present and the future

Conventional oxygen therapy (COT) and noninvasive ventilation (NIV) have been considered for decades as frontline treatment for acute or chronic respiratory failure. However, COT can be insufficient in severe hypoxaemia whereas NIV, although highly effective, is poorly tolerated by patients and its use requires a specific expertise. High-flow nasal cannula (HFNC) is an emerging technique, designed to provide oxygen at high flows with an optimal degree of heat and humidification, which is well tolerated and easy to use in all clinical settings. Physiologically, HFNC reduces the anatomical dead space and improves carbon dioxide wash-out, reduces the work of breathing, and generates a positive end-expiratory pressure and a constant fraction of inspired oxygen. Clinically, HFNC effectively reduces dyspnoea and improves oxygenation in respiratory failure from a variety of aetiologies, thus avoiding escalation to more invasive supports. In recent years it has been adopted to treat de novo hypoxaemic respiratory failure, exacerbation of chronic obstructive pulmonary disease (COPD), postintubation hypoxaemia and used for palliative respiratory care. While the use of HFNC in acute respiratory failure is now routine as an alternative to COT and sometimes NIV, new potential applications in patients with chronic respiratory diseases (e.g. domiciliary treatment of patients with stable COPD), are currently under evaluation and will become a topic of great interest in the coming years.

Effect of high flow nasal cannula on peripheral muscle oxygenation and hemodynamic during paddling exercise in patients with chronic obstructive pulmonary disease: a randomized controlled trial

Background

Exercise training for patients with chronic obstructive pulmonary disease (COPD) improves their endurance and oxygenation. Supplemental oxygen delivered by high flow nasal cannula (HFNC) reportedly improves the clinical outcomes during high-intensity exercise. However, the physical benefits of the provision of supplemental oxygen with HFNC for the improvement of exercise performance have not been fully investigated. This randomized trial aimed to evaluate the effect of HFNC on the hemodynamic status and peripheral muscle microcirculation during exercise training.

Methods

In this multicenter, randomized controlled parallel two-group study, 32 patients with moderate to severe COPD were randomly assigned into the nasal cannula (NC) group (n=15) with a flow rate of 2–3 L/min or the HFNC group (n=17) with a flow rate of 45 L/min for twelve 40 min exercise training sessions.

Results

The mean cardiac index (CI) and stroke volume (SV) of the NC group in the first session were significantly lower than those of the HFNC group (3.68±0.76 vs. 4.5±0.76 L/min/m², P=0.014; 63.03±9.87 vs. 74.22±19.48, P=0.002, respectively). The systemic vascular resistance (SVR) of the NC group was significantly lower in the seventh session than in the first session (891±287 vs. 1,138±381 dyn-s/cm⁵, respectively, P=0.048). The mean deoxyhemoglobin level was higher in the HFNC group in the 1^st session and lower in the 12^th session (1.09±9.04 vs. 7.3±7.3 µm, P=0.046). The COPD Assessment Test score, Modified Medical Research Council scale score, maximum inspiratory pressure (MIP), and maximum expiratory pressure were different within and between the groups.

Conclusions

HFNC, with a lower oxygen concentration than that used with a traditional NC, yielded lower deoxygenated hemoglobin levels after 12 suboptimal exercise training sessions. In contrast, the higher oxygen concentration delivered by NC reduced SVR. The COPD assessment score improved on exercise training, regardless of the supplemental oxygen delivery method.

The impact of high-flow nasal cannula oxygen therapy on exercise capacity in fibrotic interstitial lung disease: a proof-of-concept randomized controlled crossover trial

Background

Patients with fibrotic interstitial lung disease (FILD) often experience gas exchange abnormalities and ventilatory limitations, resulting in reduced exercise capacity. High-flow nasal cannula (HFNC) oxygen therapy is a novel treatment, whose physiological beneficial effects have been demonstrated in various clinical settings. We hypothesized that HFNC oxygen therapy might be superior to conventional oxygen therapy for improving exercise capacity in FILD patients.

Methods

We performed a prospective randomized controlled crossover trial with a high-intensity constant work-rate endurance test (CWRET) using HFNC (50 L/min, FiO₂ 0.5) and a venturi mask (VM) (15 L/min, FiO₂ 0.5) for oxygen delivery in FILD patients. The primary outcome variable was endurance time. The secondary outcome variables were SpO₂, heart rate, Borg scale (dyspnea and leg fatigue), and patient’s comfort.

Results

Seven hundred and eleven patients were screened and 20 eligible patients were randomized. All patients completed the trial. The majority of patients were good responders to VM and HFNC compared with the baseline test (VM 75%; HFNC 65%). There was no significant difference in endurance time between HFNC and VM (HFNC 6.8 [95% CI 4.3–9.3] min vs VM 7.6 [95% CI 5.0–10.1] min, p = 0.669). No significant differences were found in other secondary endpoints. Subgroup analysis with HFNC good responders revealed that HFNC significantly extended the endurance time compared with VM (VM 6.4 [95%CI 4.5–8.3] min vs HFNC 7.8 [95%CI 5.8–9.7] min, p = 0.046), while no similar effect was observed in the VM good responders.

Conclusions

HFNC did not exceed the efficacy of VM on exercise capacity in FILD, but it may be beneficial if the settings match. Further large studies are needed to confirm these findings.

Trial registration

UMIN-CTR: UMIN000021901.

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.

Acute Low-Dose Hyperoxia during a Single Bout of High-Intensity Interval Exercise Does Not Affect Red Blood Cell Deformability and Muscle Oxygenation in Trained Men-A Randomized Crossover Study

Recent technological developments provide easy access to use an artificial oxygen supply (hyperoxia) during exercise training. The aim of this study was to assess the efficacy of a commercially available oxygen compressor inducing low-dose hyperoxia, on limiting factors of endurance performance. Thirteen active men (age 24 ± 3 years) performed a high-intensity interval exercise (HIIE) session (5 × 3 min at 80% of W_max, separated by 2 min at 40% W_max) on a cycle ergometer, both in hyperoxia (4 L∙min⁻¹, 94% O₂, HYP) or ambient conditions (21% O₂, NORM) in randomized order. The primary outcome was defined as red blood cell deformability (RBC-D), while our secondary interest included changes in muscle oxygenation. RBC-D was expressed by the ratio of shear stress at half-maximal deformation (SS¹/₂) and maximal deformability (EI_max) and muscle oxygenation of the rectus femoris muscle was assessed by near-infrared spectroscopy. No statistically significant changes occurred in SS¹/₂ and EI_max in either condition. The ratio of SS¹/₂ to EI_max statistically decreased in NORM (p < 0.01; Δ: −0.10; 95%CI: −0.22, 0.02) but not HYP (p > 0.05; Δ: −0.16; 95%CI: −0.23, −0.08). Muscle oxygenation remained unchanged. This study showed that low-dose hyperoxia during HIIE using a commercially available device with a flow rate of only 4 L·min⁻¹ may not be sufficient to induce acute ergogenic effects compared to normoxic conditions.

Domiciliary high-flow treatment in patients with COPD and chronic hypoxic failure: In whom can we reduce exacerbations and hospitalizations?

INTRODUCTION

Domiciliary High-flow, humidified, nasal cannula (HFNC) is a possible add-on in patients with chronic respiratory diseases. This post-hoc study investigates benefit of HFNC in subgroups of advanced COPD patients with chronic hypoxic failure on reduction of exacerbations and hospitalizations.

METHODS

One hundred patients were randomized to HFNC in a previous trial. Subgroups with 0-1 (N = 32) respectively two or more (2+) (N = 68) exacerbations 12 months pre-study were investigated. Changes in number of exacerbations and hospitalizations pre- and in study were analyzed, corrected for HFNC days with HFNC.

RESULTS

Patients were comparable at baseline. Exacerbations increased in subgroup 0-1 (p = 0.01) and decreased in subgroup 2+ (p = 0.03). Correcting for HFNC days no correlation was seen in subgroup 0-1 (p = 0.08), but in subgroup 2+ (p<0.001). Number of hospitalizations increased in subgroup 0-1 (p = 0.01) with no change in days of hospitalization (p = 0.08). Number and days of hospitalization decreased in subgroup 2+ (p = 0.002 resp. 0.025). Correcting for HFNC days no correlation was found in number or days of hospitalization in subgroup 0-1 (p = 0.48 and p = 0.65). Positive correlation was found in subgroup 2+ (both p<0.001).

CONCLUSION

In patients with advanced COPD, chronic hypoxic failure and two or more exacerbations per year, HFNC significantly reduced exacerbations and hospitalizations.

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.

Physiological effects of high-flow oxygen in tracheostomized patients

Background

High-flow oxygen therapy via nasal cannula (HFOT_NASAL) increases airway pressure, ameliorates oxygenation and reduces work of breathing. High-flow oxygen can be delivered through tracheostomy (HFOT_TRACHEAL), but its physiological effects have not been systematically described. We conducted a cross-over study to elucidate the effects of increasing flow rates of HFOT_TRACHEAL on gas exchange, respiratory rate and endotracheal pressure and to compare lower airway pressure produced by HFOT_NASAL and HFOT_TRACHEAL.

Methods

Twenty-six tracheostomized patients underwent standard oxygen therapy through a conventional heat and moisture exchanger, and then HFOT_TRACHEAL through a heated humidifier, with gas flow set at 10, 30 and 50 L/min. Each step lasted 30 min; gas flow sequence during HFOT_TRACHEAL was randomized. In five patients, measurements were repeated during HFOT_TRACHEAL before tracheostomy decannulation and immediately after during HFOT_NASAL. In each step, arterial blood gases, respiratory rate, and tracheal pressure were measured.

Results

During HFOT_TRACHEAL, PaO₂/FiO₂ ratio and tracheal expiratory pressure slightly increased proportionally to gas flow. The mean [95% confidence interval] expiratory pressure raise induced by 10-L/min increase in flow was 0.2 [0.1–0.2] cmH₂O (ρ = 0.77, p < 0.001). Compared to standard oxygen, HFOT_TRACHEAL limited the negative inspiratory swing in tracheal pressure; at 50 L/min, but not with other settings, HFOT_TRACHEAL increased mean tracheal expiratory pressure by (mean difference [95% CI]) 0.4 [0.3–0.6] cmH₂O, peak tracheal expiratory pressure by 0.4 [0.2–0.6] cmH₂O, improved PaO₂/FiO₂ ratio by 40 [8–71] mmHg, and reduced respiratory rate by 1.9 [0.3–3.6] breaths/min without PaCO₂ changes. As compared to HFOT_TRACHEAL, HFOT_NASAL produced higher tracheal mean and peak expiratory pressure (at 50 L/min, mean difference [95% CI]: 3 [1–5] cmH₂O and 4 [1–7] cmH₂O, respectively).

Conclusions

As compared to standard oxygen, 50 L/min of HFOT_TRACHEAL are needed to improve oxygenation, reduce respiratory rate and provide small degree of positive airway expiratory pressure, which, however, is significantly lower than the one produced by HFOT_NASAL.

Reduction of PaCO2 by high-flow nasal cannula in acute hypercapnic respiratory failure patients receiving conventional oxygen therapy

Background:

It has been suggested that a high-flow nasal cannula (HFNC) could help to remove carbon dioxide (CO₂) from anatomical dead spaces, but evidence to support that is lacking. The objective of this study was to elucidate whether use of an HFNC could reduce the arterial partial pressure of CO₂ (PaCO₂) in patients with acute hypercapnic respiratory failure who are receiving conventional oxygen (O₂) therapy.

Methods:

A propensity score-matched observational study was conducted to evaluate patients treated with an HFNC for acute hypercapnic respiratory failure from 2015 to 2016. The hypercapnia group was defined as patients with a PaCO₂ >50 mm Hg and arterial pH <7.35.

Results:

Eighteen patients in the hypercapnia group and 177 patients in the nonhypercapnia group were eligible for the present study. Eighteen patients in each group were matched by propensity score. Decreased PaCO₂ and consequent pH normalization over time occurred in the hypercapnia group (P=0.002 and P=0.005, respectively). The initial PaCO₂ level correlated linearly with PaCO₂ removal after the use of an HFNC (R²=0.378, P=0.010). The fraction of inspired O₂ used in the intensive care unit was consistently higher for 48 hours in the nonhypercapnia group. Physiological parameters such as respiratory rate and arterial partial pressure of O₂ improved over time in both groups.

Conclusions:

Physiological parameters can improve after the use of an HFNC in patients with acute hypercapnic respiratory failure given low-flow O₂ therapy via a facial mask. Further studies are needed to identify which hypercapnic patients might benefit from an HFNC.

Aeration changes induced by high flow nasal cannula are more homogeneous than those generated by non-invasive ventilation in healthy subjects

BACKGROUND

Non-invasive mechanical ventilation (NIV) is a standard respiratory support technique used in intensive care units. High-Flow Nasal Cannula (HFNC) has emerged as an alternative, but further evidence is needed. The lung aeration and diaphragm changes achieved with these two strategies in healthy subjects have not been compared to date.

METHODS

Twenty healthy subjects were recruited. Ten were ventilated with NIV and ten underwent HFNC. Lung impedance and diaphragmatic ultrasound measurements were performed before and after 30 min of respiratory support. The Mar-index was defined as the ratio of the diaphragm excursion-time index to the respiratory rate.

RESULTS

Both groups showed significant decreases in respiratory rate (NIV: 14.4 (4.1) vs 10.4 (1.6), p = 0.009; HFNC: 13.6 (4.3) vs 7.9 (1.5) bpm, p = 0.002) and significant increases in the end-expiratory lung impedance (EELI) (NIV: 66,348(10,761) vs. 73,697 (6858), p = 0.005; HFNC: 66,252 (9793) vs 69,869 (9135), p = 0.012). NIV subjects showed a significant increase in non-dependent silent spaces (4.13 (2.25) vs 5.81 (1.49)%, p = 0.037) while the increase was more homogeneous with HFNC. The variation in EELI tended to be higher in NIV than in HFNC (8137.08 (6152.04) vs 3616.94 (3623.03), p = 0.077). The Mar-index was higher in HFNC group (13.15 vs 5.27 cm-sec²/bpm, p = 0.02).

CONCLUSIONS

NIV and HFNC increased EELI in healthy subjects, suggesting an increase in the functional residual capacity. The EELI increase may be higher in NIV, but HFNC produced a more homogeneous change in lung ventilation. HFNC group has a higher MAR-index that could reflect a different ventilatory system adaptation.

High flow nasal cannula oxygen therapy versus non-invasive ventilation for chronic obstructive pulmonary disease with acute-moderate hypercapnic respiratory failure: an observational cohort study

Background

High-flow nasal cannula (HFNC) oxygen therapy in acute hypoxic respiratory failure is becoming increasingly popular. However, evidence to support the use of HFNC in acute respiratory failure (ARF) with hypercapnia is limited.

Methods

Chronic obstructive pulmonary disease (COPD) patients with moderate hypercapnic ARF (arterial blood gas pH 7.25–7.35, PaCO₂>50 mmHg) who received HFNC or non-invasive ventilation (NIV) in the intensive care uint from April 2016 to March 2018 were analyzed retrospectively. The endpoint was treatment failure, defined as either invasive ventilation, or a switch to the other study treatment (NIV for patients in the NFNC group, and vice-versa), and 28-day mortality.

Results

Eighty-two COPD patients (39 in the HFNC group and 43 in the NIV group) were enrolled in this study. The mean age was 71.8±8.2 and 54 patients (65.9%) were male. The treatment failed in 11 out of 39 patients with HFNC (28.2%) and in 17 of 43 patients with NIV (39.5%) (P=0.268). No significant differences were found for 28-day mortality (15.4% in the HFNC group and 14% in the NIV group, P=0.824). During the first 24 hrs of treatment, the number of nursing airway care interventions in the HFNC group was significantly less than in the NIV group, while the duration of device application was significantly longer in the HFNC group (all P<0.05). Skin breakdown was significantly more common in the NIV group (20.9% vs 5.1%, P<0.05).

Conclusion

Among COPD patients with moderate hypercarbic ARF, the use of HFNC compared with NIV did not result in increased rates of treatment failure, while there were fewer nursing interventions and skin breakdown episodes reported in the HFNC group.

Efficacy and safety of high-flow nasal cannula oxygen therapy in moderate acute hypercapnic respiratory failure

Objective

To assess the efficacy and safety of high-flow nasal cannula oxygen therapy in treating moderate hypercapnic respiratory failure in patients who cannot tolerate or have contraindications to noninvasive mechanical ventilation.

Methods

A prospective observational 13-month study involving subjects admitted to an intensive care unit with or developing moderate hypercapnic respiratory failure. Clinical and gas exchange parameters were recorded at regular intervals during the first 24 hours. The endpoints were a oxygen saturation between 88 and 92% along with a reduction in breathing effort (respiratory rate) and pH normalization (≥ 7.35). Subjects were considered nonresponders if they required ventilatory support.

Results

Thirty subjects were treated with high-flow nasal cannula oxygen therapy. They consisted of a mixed population with chronic obstructive pulmonary disease exacerbation, acute cardiogenic pulmonary edema, and postoperative and postextubation respiratory failure. A nonsignificant improvement was observed in respiratory rate (28.0 ± 0.9 versus 24.3 ± 1.5, p = 0.22), which was apparent in the first four hours of treatment. The pH improved, although normal levels were only reached after 24 hours on high-flow nasal cannula therapy (7.28 ± 0.02 versus 7.37 ± 0.01, p = 0.02). The rate of nonresponders was 13.3% (4 subjects), of whom one needed and accepted noninvasive mechanical ventilation and three required intubation. Intensive care unit mortality was 3.3% (1 subject), and a patient died after discharge to the ward (hospital mortality of 6.6%).

Conclusion

High-flow nasal cannula oxygen therapy is effective for moderate hypercapnic respiratory failure as it helps normalize clinical and gas exchange levels with an acceptable rate of nonresponders who require ventilatory support.

Management of Chronic Respiratory Failure in Interstitial Lung Diseases: Overview and Clinical Insights

Interstitial lung diseases (ILDs) may be complicated by chronic respiratory failure (CRF), especially in the advanced stages. Aim of this narrative review is to evaluate the current evidence in management of CRF in ILDs. Many physiological mechanisms underlie CRF in ILDs, including lung restriction, ventilation/perfusion mismatch, impaired diffusion capacity and pulmonary vascular damage. Intermittent exertional hypoxemia is often the initial sign of CRF, evolving, as ILD progresses, into continuous hypoxemia. In the majority of the cases, the development of CRF is secondary to the worsening of the underlying disease; however, associated comorbidities may also play a role. When managing CRF in ILDs, the need for pulmonary rehabilitation, the referral to lung transplant centers and palliative care should be assessed and, if necessary, promptly offered. Long-term oxygen therapy is commonly prescribed in case of resting or exertional hypoxemia with the purpose to decrease dyspnea and improve exercise tolerance. High-Flow Nasal Cannula oxygen therapy may be used as an alternative to conventional oxygen therapy for ILD patients with severe hypoxemia requiring both high flows and high oxygen concentrations. Non-Invasive Ventilation may be used in the chronic setting for palliation of end-stage ILD patients, although the evidence to support this application is very limited.

Preoperative Evaluation: Estimation of Pulmonary Risk Including Obstructive Sleep Apnea Impact

One in 4 deaths occurring within a week of surgery are related to pulmonary complications, making it the second most common serious morbidity after cardiovascular events. The most significant predictors of the postoperative pulmonary complications (PPCs) are American Society of Anesthesiologists physical status, advanced age, dependent functional status, surgical site, and duration of surgery. The overall risk of PPCs can be predicted using scores that incorporate readily available clinical data.

Aerosol Delivery to a Critically Ill Patient: A Big Issue Easily Solved by Developing Guidelines

Nowadays, therapeutic aerosols are commonly delivered to mechanically ventilated patients by nebulizers and pressurized metered dose inhaler attached to an adapter or a spacer. Studies with asthmatics and chronic obstructive pulmonary disease patients have confirmed that aerosol delivery during mechanical ventilation is feasible. They have also reported that the inhaled drugs administered during mechanical ventilation provide greater and faster clinical outcomes than when delivering during spontaneous unassisted breathing. Researchers studied factors that would affect aerosol delivery during mechanical ventilation. Even with the tremendous amount of publications in this area, there have still been no recommendations or guidelines released to help respiratory therapists in their decision as to when to deliver aerosol to ventilated patients. Mostly, respiratory therapists read the literature and decide accordingly what to do and which device to use for their patients. This puts the patients at risk of receiving a sub-therapeutic or toxic dose of the inhaled aerosol. Some studies raise an alarm of physician decision upon reading any released publication related to aerosol delivery in mechanical ventilation without a trusted recommendation and guidelines. This increases the need for the development of recommendations and guidelines, by a trusted board or society, for aerosol delivery to such critically ill patients. To summarize, inhaled drugs administered to critically ill patients is of benefit compared to taking the patient off the ventilator and delivering during spontaneous unassisted breathing. However, dependable guidelines are needed to optimize aerosol delivery.

Long-term effects of oxygen-enriched high-flow nasal cannula treatment in COPD patients with chronic hypoxemic respiratory failure

BACKGROUND

This study investigated the long-term effects of humidified high-flow nasal cannula (HFNC) in COPD patients with chronic hypoxemic respiratory failure treated with long-term oxygen therapy (LTOT).

PATIENTS AND METHODS

A total of 200 patients were randomized into usual care ± HFNC. At inclusion, acute exacerbation of COPD (AECOPD) and hospital admissions 1 year before inclusion, modified Medical Research Council (mMRC) score, St George's Respiratory Questionnaire (SGRQ), forced expiratory volume in 1 second (FEV1), 6-minute walk test (6MWT) and arterial carbon dioxide (PaCO2) were recorded. Patients completed phone interviews at 1, 3 and 9 months assessing mMRC score and AECOPD since the last contact. At on-site visits (6 and 12 months), mMRC, number of AECOPD since last contact and SGRQ were registered and FEV1, FEV1%, PaCO2 and, at 12 months, 6MWT were reassessed. Hospital admissions during the study period were obtained from hospital records. Hours of the use of HFNC were retrieved from the high-flow device.

RESULTS

The average daily use of HFNC was 6 hours/day. The HFNC group had a lower AECOPD rate (3.12 versus 4.95/patient/year, p<0.001). Modeled hospital admission rates were 0.79 versus 1.39/patient/year for 12- versus 1-month use of HFNC, respectively (p<0.001). The HFNC group had improved mMRC scores from 3 months onward (p<0.001) and improved SGRQ at 6 and 12 months (p=0.002, p=0.033) and PaCO2 (p=0.005) and 6MWT (p=0.005) at 12 months. There was no difference in all-cause mortality.

CONCLUSION

HFNC treatment reduced AECOPD, hospital admissions and symptoms in COPD patients with hypoxic failure.

Comparison of pulsed versus continuous oxygen delivery using realistic adult nasal airway replicas

BACKGROUND

Portable oxygen concentrators (POCs) typically include pulse flow (PF) modes to conserve oxygen. The primary aims of this study were to develop a predictive in vitro model for inhaled oxygen delivery using a set of realistic airway replicas, and to compare PF for a commercial POC with steady flow (SF) from a compressed oxygen cylinder.

METHODS

Experiments were carried out using a stationary compressed oxygen cylinder, a POC, and 15 adult nasal airway replicas based on airway geometries derived from medical images. Oxygen delivery via nasal cannula was tested at PF settings of 2.0 and 6.0, and SF rates of 2.0 and 6.0 L/min. A test lung simulated three breathing patterns representative of a chronic obstructive pulmonary disease patient at rest, during exercise, and while asleep. Volume-averaged fraction of inhaled oxygen (F_iO₂) was calculated by analyzing oxygen concentrations sampled at the exit of each replica and inhalation flow rates over time. POC pulse volumes were also measured using a commercial O₂ conserver test system to attempt to predict F_iO₂ for PF.

RESULTS

Relative volume-averaged F_iO₂ using PF ranged from 68% to 94% of SF values, increasing with breathing frequency and tidal volume. Three of 15 replicas failed to trigger the POC when used with the sleep breathing pattern at the 2.0 setting, and four of 15 replicas failed to trigger at the 6.0 setting. F_iO₂ values estimated from POC pulse characteristics followed similar trends but were lower than those derived from airway replica experiments.

CONCLUSION

For the POC tested, PF delivered similar, though consistently lower, volume-averaged F_iO₂ than SF rates equivalent to nominal PF settings. Assessment of PF oxygen delivery using POC pulse characteristics alone may be insufficient; testing using airway replicas is useful in identifying possible cases of failure and may provide a better assessment of F_iO₂.

Impact of Heated Humidified High Flow Air via Nasal Cannula on Respiratory Effort in Patients with Chronic Obstructive Pulmonary Disease

Background: High flow nasal cannula therapy (HFNC) has been widely adopted for respiratory distress, and evidence suggests that purging dead space of the upper airway improves gas fractions in the lung. This study tests the hypothesis that HFNC with room air could be as effective as low flow oxygen in chronic obstructive pulmonary disease (COPD). Methods: Thirty-two COPD patients prescribed 1 - 2 L/min of oxygen were studied. The conditions tested consisted of a control (CTRL; no therapy), then in random order HFNC and prescribed low flow oxygen (LFO). HFNC was the highest flow tolerated up to 35 L/min without supplemental oxygen. Arterial blood gases (ABGs), respiratory rate (RR), heart rate (HR) and tidal volume (V_T) were measured at the end of each condition. Results: Arterial oxygen (PaO₂) was greater (p < 0.001) for LFO than both HFNC and CTRL (CTRL=57.4±6.1mmHg, HFNC=58.6±8.3mmHg, LFO=72.6±10.2mmHg). HFNC reduced RR by 11% (p<0.05) from CTRL and LFO (CTRL=20.2±3.8br/min, HFNC=17.9±3.3br/min, LFO=20.2±3.7br/min) with no differences in V_T. There were no differences between arterial carbon dioxide (PaCO₂) (CTRL=45.5±4.9mmHg, HFNC=45.0±5.3mmHg, LFO=46.0±3.9mmHg). Conclusions: HFNC resulted in a clinically relevant reduction in ventilatory effort with no change in ABG indicating a gas equilibrium effect of purging anatomical dead space. Clinical Trial Registration: ClinicalTrials.gov ID: NCT00990210.

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.

High-flow nasal cannula oxygen therapy vs conventional oxygen therapy in cardiac surgical patients: A meta-analysis

INTRODUCTION

The use of high-flow nasal cannula (HFNC) for the treatment of many diseases has gained increasing popularity. In the present meta-analysis, we aimed to assess the efficacy and safety of HFNCs compared with conventional oxygen therapy (COT) in adult postextubation cardiac surgical patients.

METHOD

We reviewed the Embase, PubMed, Cochrane Central Register of Controlled Trials, Wanfang databases, and the China National Knowledge Infrastructure. Two investigators independently collected the data and assessed the quality of each study. RevMan 5.3 was used for the present meta-analysis.

RESULTS

We included 495 adult postextubation cardiac surgical patients. There was no significant heterogeneity among the studies. Compared with COT, HFNCs were associated with a significant reduction in the escalation of respiratory support (risk ratio, 0.61; 95% confidence interval [CI], 0.46-0.82; z = 3.32, P < .001). There were no significant differences in the reintubation rate (risk ratio, 0.96; 95% CI, 0.04-24.84; z = 0.02, P = .98) or length of intensive care unit stay (weighted mean difference, 0.13; 95% CI, -0.88 to 7.92; z = 1.57, P = .12) between the 2 groups. No severe complications were reported in either group.

CONCLUSIONS

The HFNC could reduce the need for escalation of respiratory support compared with COT, and it could be safely administered in adult postextubation cardiac surgical patients.

Nasal high-flow therapy reduces work of breathing compared with oxygen during sleep in COPD and smoking controls: a prospective observational study

Patients with chronic obstructive pulmonary disease (COPD) endure excessive resistive and elastic loads leading to chronic respiratory failure. Oxygen supplementation corrects hypoxemia but is not expected to reduce mechanical loads. Nasal high-flow (NHF) therapy supports breathing by reducing dead space, but it is unclear how it affects mechanical loads of patients with COPD. The objective of this study was to compare the effects of low-flow oxygen and NHF therapy on ventilation and work of breathing (WOB) in patients with COPD and controls during sleep. Patients with COPD (n = 12) and controls (n = 6) were recruited and submitted to polysomnography to measure sleep parameters and ventilation in response to administration of oxygen and NHF. A subset of six patients also had an esophageal catheter inserted for the purpose of measuring WOB. Patients with COPD had similar minute ventilation (V̇e) but lower tidal volumes than matched controls. With oxygen, [Formula: see text]was increased and V̇e was reduced in both controls and patients with COPD, but there was an increase in transcutaneous CO₂ levels. NHF produced a greater reduction in V̇e and was associated with a reduction in CO₂ levels. Although NHF halved WOB, oxygen produced only a minor reduction in this parameter. We conclude that oxygen produced little change in WOB, which was associated with CO₂ elevations. On the other hand, NHF produced a large reduction in V̇e and WOB with a concomitant decrease in CO₂ levels. Our data indicate that NHF improves alveolar ventilation during sleep compared with oxygen and room air in patients with COPD and therefore can decrease their cost of breathing.

NEW & NOTEWORTHY

Nasal high-flow (NHF) therapy can support ventilation in patients with chronic obstructive pulmonary disease during sleep by decreasing the work of breathing and improving CO₂ levels. On the other hand, oxygen supplementation corrects hypoxemia, but it produces only a minimal reduction in work of breathing and is associated with increased CO₂ levels. Therefore, NHF can be a useful method to assist ventilation in patients with increased respiratory mechanical loads.