Exertional oxygen of limited benefit in patients with chronic obstructive pulmonary disease and mild hypoxemia

Efficacy of supplemental oxygen for dyspnea relief in patients with advanced progressive illness: A systematic review and meta-analysis

BACKGROUND

Supplemental oxygen is widely used for dyspnea relief; however, its efficacy is yet to be verified. This study aimed to determine the efficacy of supplemental oxygen for dyspnea relief in patients with advanced progressive illness.

METHODS

In this systematic review, several databases, including MEDLINE and EMBASE, were searched to identify eligible randomized controlled trials (RCTs) on the topic published up to September 23, 2019. The search criteria included RCTs investigating patients with advanced progressive illness (advanced cancer, chronic obstructive pulmonary disease, and chronic heart failure). The study protocol was registered with PROSPERO (No. CRD42020161838). Separate analyses were pre-planned regarding the presence or absence of resting hypoxemia.

RESULTS

RCTs investigating supplemental oxygen for dyspnea relief in participants with and without resting hypoxemia (39 and five, respectively) were included in the study. Heterogeneity of supplemental oxygen for dyspnea in RCTs, including participants without resting hypoxemia was evident; hence, post-hoc analyses in four subgroups (supplemental oxygen during exercise or daily activities, short-burst oxygen, continuous supplemental oxygen, and supplemental oxygen during rehabilitation intervention) were conducted. In the meta-analysis, supplemental oxygen during exercise was found to improve dyspnea in patients without resting hypoxemia compared with that in the control (standardized mean difference = -0.57, 95% confidence interval = -0.77 to -0.38). However, supplemental oxygen for the other subgroups failed to improve patients' dyspnea.

CONCLUSION

The results of this systematic review do not support supplemental oxygen therapy for dyspnea relief in patients with advanced progressive illness, except during exercise.

Utility and outcomes among Indigenous and non-Indigenous patients requiring domiciliary oxygen therapy in the regional and rural Australian population

OBJECTIVE

To evaluate the utility and outcomes for Indigenous and non-Indigenous patients requiring domiciliary oxygen therapy.

DESIGN

Retrospective study.

SETTING

Patients residing in the regional and rural Top End Health Service region of the Northern Territory of Australia.

PARTICIPANTS

Indigenous and non-Indigenous patients prescribed domiciliary oxygen therapy between 2018 and 2020.

INTERVENTIONS

Demographics and clinical indication for domiciliary oxygen therapy and mortality were analysed.

MAIN OUTCOME MEASURES

Differences between Indigenous patients requiring domiciliary oxygen therapy in comparison with their non-Indigenous counterparts.

RESULTS

Of the 199 study participants, the majority were male (51%), non-Indigenous (77%) and urban residents (72%). Overall chronic obstructive pulmonary disease was the most common indication for domiciliary oxygen therapy (51%) followed by palliative intent (22%). Indigenous patients were significantly younger (61 vs 73 years), with a higher proportion of males (62% vs 45%, P = .039) and remote residents (62% vs 8%, P < .001). Among Indigenous patients, a significantly greater proportion of domiciliary oxygen therapy was indicated for chronic obstructive pulmonary disease and bronchiectasis (16% vs 1%, P < .001). Among non-Indigenous patients, malignancies were a more common indication for domiciliary oxygen therapy. A similar proportion of Indigenous and non-Indigenous patients were prescribed domiciliary oxygen therapy for palliative intent (31% and 20%, P = .108); however, the underlying diagnosis differed significantly, with a greater proportion of chronic obstructive pulmonary disease among Indigenous patients (43% vs 13%, P = .030) and malignancy among the non-Indigenous patients (73% vs 43%, P = .050). Mortality and length of survival were not significantly different by Indigenous status. Linear regression showed longer survival with domiciliary oxygen therapy for chronic obstructive pulmonary disease.

CONCLUSION

Indigenous Australian patients living in remote communities will likely derive the same benefits and outcomes of domiciliary oxygen therapy as non-Indigenous peers.

Nonpharmacological Therapies in COPD

Chronic obstructive pulmonary disease has recently been gaining more attention, as beyond impacting roughly 10% of the world's population, it also carries high morbidity and mortality. The mainstay of management is optimizing pharmacological therapy, but various nonpharmacological therapies have shown benefits in providing symptom improvement and relief, prevention and mitigation of exacerbations, quality of life, and even mortality rate. Such modalities include supplemental oxygen therapy, pulmonary rehabilitation, viral and bacterial vaccinations, and noninvasive positive pressure ventilation therapy.

Accompanied versus unaccompanied walking for continuous oxygen saturation measurement during 6-min walk test in COPD: a randomised crossover study

The aim of this study was to determine if there is a difference in 6-min walk test (6MWT) distance when the assessor accompanies the patient to continuously measure peripheral oxygen saturation (S_pO2) compared to the patient walking unaccompanied.

 We conducted a randomised crossover study to evaluate the impact of the assessor walking with the patient during the 6MWT (6MWT_with) versus the patient walking alone (6MWT_without). At the end of a pulmonary rehabilitation programme, each patient performed two 6MWTs in random order and separated by a 30-min rest.

 49 patients with chronic obstructive pulmonary disease (COPD) (Global Initiative for Obstructive Lung Disease classification II–IV) were included. In a regression model adjusting for period and subject, accompanying the patient resulted in a lower walking distance (mean difference −9.1 m, 95% CI −13.9– −4.3, p=0.0004). Notably, six patients walked more than 30 m farther (minimal important difference) in one of the two conditions (6MWT_with: n=1, 6MWT_without: n=5). There were no between-sequence-group differences in heart rate, dyspnoea, leg fatigue and S_pO2. The median (interquartile range) number and duration of S_pO2 signal artefacts were high but not different between the experimental conditions (6MWT_with: 17 (4–24), 34 s (7–113 s); 6 MWT_without: 11 (3–26), 24 s (4–62 s)).

 At a study population level, we observed a statistically significant difference in 6MWT distance between the two experimental conditions; however, the magnitude of difference was small and may not be clinically relevant. Nevertheless, in a clinical setting, unaccompanied walking resulted in a substantially higher walking distance in individual patients, pointing towards strictly standardised testing methodology, in particular in pre–post study designs.

Accompanied walking during a 6MWT versus unaccompanied walking results in shorter walked distance (mean difference −9.1 m, 95% CI −13.9– −4.3 m). No differences in nadir S_pO2 or oximetry artefacts were noted between accompanied and unaccompanied walking.https://bit.ly/3tBjfCq

COPD-Lower Respiratory Tract Infection Visual Analogue Score (c-LRTI-VAS) validation in stable and exacerbated patients with COPD

Background

We developed the chronic obstructive pulmonary disease (COPD)-Lower Respiratory Tract Infection-Visual Analogue Score (c-LRTI-VAS) in order to easily quantify symptoms during exacerbations in patients with COPD. This study aimed to validate this score.

Methods

In our study, patients with stable COPD as well as those with an acute exacerbations of COPD (AECOPD) were included. The results of c-LRTI-VAS were compared with other markers of disease activity (lung function parameters, oxygen saturation and two health related quality of life questionnaires (St Georges Respiratory Questionnaire (SGRQ) and Clinical COPD Questionnaire (CCQ)) and validity, reliability and responsiveness were assessed.

Results

Eighty-eight patients with clinically stable COPD and 102 patients who had an AECOPD completed the c-LRTI-VAS questionnaire. When testing on two separate occasions for repeatability, no statistically significant difference between total scores was found 0.143 (SD 5.42) (p=0.826). Internal consistency was high across items (Cronbach’s apha 0.755). Correlation with SGRQ and CCQ total scores was moderate to high. After treatment for hospitalised AECOPD, the mean c-LRTI-VAS total score improved 8.14 points (SD 9.13; p≤0.001).

Conclusions

c-LRTI-VAS showed proper validity, responsiveness to change and moderate to high correlation with other questionnaires. It, therefore, appears a reliable tool for symptom measurement during AECOPD.

Trial registration number

NCT01232140.

[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.

Impact of exercise training and supplemental oxygen on submaximal exercise performance in patients with COPD

Functional impairment caused by chronic obstructive pulmonary disease (COPD) impacts on activities of daily living and quality of life. Indeed, patients' submaximal exercise capacity is of crucial importance. It was the aim of this study to investigate the effects of an exercise training intervention with and without supplemental oxygen on submaximal exercise performance. This is a secondary analysis of a randomized, controlled, double-blind, crossover trial. 29 COPD patients (63.5 ± 5.9 years; FEV₁ 46.4 ± 8.6%) completed two consecutive 6-week periods of high-intensity interval cycling and strength training, which was performed three times/week with either supplemental oxygen or medical air (10 L/min). Submaximal exercise capacity as well as the cardiocirculatory, ventilatory, and metabolic response were evaluated at isotime (point of termination in the shortest cardiopulmonary exercise test), at physical work capacity at 110 bpm of heart rate (PWC 110), at the anaerobic threshold (AT), and at the lactate-2 mmol/L threshold. After 12 weeks of exercise training, patients improved in exercise tolerance, shown by decreased cardiocirculatory (heart rate, blood pressure) and metabolic (respiratory exchange ratio, lactate) effort at isotime; ventilatory response was not affected. Submaximal exercise capacity was improved at PWC 110, AT and the lactate-2 mmol/L threshold, respectively. Although supplemental oxygen seems to affect patients' work rate at AT and the lactate-2 mmol/L threshold, no other significant effects were found. The improved submaximal exercise capacity and tolerance might counteract patients' functional impairment. Although cardiovascular and metabolic training adaptations were shown, ventilatory efficiency remained essentially unchanged. The impact of supplemental oxygen seems less important on submaximal training effects.

Physiologic Effects of Oxygen Supplementation During Exercise in Chronic Obstructive Pulmonary Disease

Supplemental long-term oxygen therapy (LTOT) is a well-established therapy that improves mortality in patients with chronic obstructive pulmonary disease (COPD) with resting hypoxemia. In the large number of patients with COPD who do not have severe resting hypoxemia but who desaturate with exercise, the clinical benefits that can be obtained by supplemental O₂ therapy during exercise is an area of interest and active research. A summary of current evidence for benefits of supplemental O₂ therapy and a review of physiologic mechanisms underlying published observations are reviewed in this article.

Home Oxygen in Chronic Obstructive Pulmonary Disease

Two landmark trials conducted more than 35 years ago provided scientific evidence that, under very specific circumstances, long-term oxygen therapy (LTOT) may prolong life. These two trials enrolled 290 patients with chronic obstructive pulmonary disease and severe daytime hypoxemia documented by direct arterial blood gas measurement. From that time, LTOT became a standard of care, and the indications for oxygen therapy expanded to include nocturnal oxygen therapy for isolated nocturnal oxygen desaturation, ambulatory oxygen to correct exercise-induced desaturation, and short-burst oxygen to relieve dyspnea. In most cases, the rationale for broadening the indications for oxygen therapy is that, if hypoxemia exists, correcting it by increasing the Fi_O2 should help. However, with the exception of LTOT in severely hypoxemic patients with chronic obstructive pulmonary disease, randomized controlled trials of oxygen therapy have failed to demonstrate clinically significant benefits. Also, adherence to LTOT is usually suboptimal. Important areas for future research include improving understanding of the mechanisms of action of supplemental oxygen, the clinical and biochemical predictors of responsiveness to LTOT, the methods for measuring and enhancing adherence to LTOT, and the cost-effectiveness of oxygen therapy. A standardization of terminology to describe the use of supplemental oxygen at home is provided.

Airflow relieves chronic breathlessness in people with advanced disease: An exploratory systematic review and meta-analyses

BACKGROUND

Chronic breathlessness is a neglected symptom of advanced diseases.

AIM

To examine the effect of airflow for chronic breathlessness relief.

DESIGN

Exploratory systematic review and meta-analysis.

DATA SOURCES

Medline, CINAHL, AMED and Cochrane databases were searched (1985-2018) for observational studies or randomised controlled trials of airflow as intervention or comparator. Selection against predefined inclusion criteria, quality appraisal and data extraction was conducted by two independent reviewers with access to a third for unresolved differences. 'Before and after' breathlessness measures from airflow arms were analysed. Meta-analysis was carried out where possible.

RESULTS

In all, 16 of 78 studies (n = 929) were included: 11 randomised controlled trials of oxygen versus medical air, 4 randomised controlled trials and 1 fan cohort study. Three meta-analyses were possible: (1) Fan at rest in three studies (n = 111) offered significant benefit for breathlessness intensity (0-100 mm visual analogue scale and 0-10 numerical rating scale), mean difference -11.17 (95% confidence intervals (CI) -16.60 to -5.74), p = 0.06 I² 64%. (2) Medical air via nasal cannulae at rest in two studies (n = 89) improved breathlessness intensity (visual analogue scale), mean difference -12.0 mm, 95% CI -7.4 to -16.6, p < 0.0001 I² = 0%. (3) Medical airflow during a constant load exercise test before and after rehabilitation (n = 29) in two studies improved breathlessness intensity (modified Borg scale, 0-10), mean difference -2.9, 95% CI -3.2 to -2.7, p < 0.0001 I² = 0%.

CONCLUSION

Airflow appears to offer meaningful relief of chronic breathlessness and should be considered as an adjunct treatment in the management of breathlessness.

Supplemental oxygen in patients with stable chronic obstructive pulmonary disease: evidence from Nocturnal Oxygen Treatment Trial to Long-term Oxygen Treatment Trial

PURPOSE OF REVIEW

Oxygen therapy was the first treatment shown to prolong life in patients with chronic obstructive pulmonary disease (COPD) and has been joined by lung volume reduction surgery in selected patients with emphysema, smoking cessation, and potentially noninvasive ventilation in chronic hypercapneic respiratory failure. Although there is consensus around the survival-enhancing effect of supplemental oxygen (SupplO2) for patients with chronic severe hypoxemia at rest, the impact of SupplO2 for COPD patients with moderate hypoxemia and exertional desaturation had been less clear.

RECENT FINDINGS

The recently published Long-term Oxygen Treatment Trial (LOTT) showed no benefit of SupplO2 for the composite outcome of survival and all-cause hospitalizations, or for component outcomes, severe COPD exacerbations, or quality of life in COPD patients with moderate resting hypoxemia or room air normoxemia with exercise desaturation.

SUMMARY

Results of the LOTT challenge the practice of prescribing SupplO2 for patients with COPD and moderate resting hypoxemia or isolated exertional desaturation. In the context that LOTT may not have recruited patients for whom SupplO2 conferred subjective benefit, there may be a role for short-term trials of SupplO2 with assessment of subjective benefit in such patients.

Home oxygen therapy: re-thinking the role of devices

INTRODUCTION

A range of devices are available for delivering and monitoring home oxygen therapy (HOT). Guidelines do not give indications for the choice of the delivery device but recommend the use of an ambulatory system in subjects on HOT whilst walking. Areas covered: We provide a clinical overview of HOT and review traditional and newer delivery and monitoring devices for HOT. Despite relevant technology advancements, clinicians, faced with many challenges when they prescribe oxygen therapy, often remain familiar to traditional devices and continuous flow delivery of oxygen. Some self-filling delivery-less devices could increase the users' level of independence with ecological advantage and, perhaps, reduced cost. Some newer portable oxygen concentrators are being available, but more work is needed to understand their performances in different diseases and clinical settings. Pulse oximetry has gained large diffusion worldwide and some models permit long-term monitoring. Some closed-loop portable monitoring devices are also able to adjust oxygen flow automatically in accordance with the different needs of everyday life. This might help to improve adherence and the practice of proper oxygen titration that has often been omitted because difficult to perform and time-consuming. Expert commentary: The prescribing physicians should know the characteristics of newer devices and use technological advancements to improve the practice of HOT.

Long-Term Oxygen Therapy in COPD Patients Who Do Not Meet the Actual Recommendations

Chronic respiratory failure due to chronic obstructive pulmonary disease (COPD) is an increasing problem worldwide. Many patients with severe COPD develop hypoxemic respiratory failure during the natural progression of disease. Long-term oxygen therapy (LTOT) is a well-established supportive treatment for COPD and has been shown to improve survival in patients who develop chronic hypoxemic respiratory failure. The degree of hypoxemia is severe when partial pressure of oxygen in arterial blood (PaO₂) is ≤55 mmHg and moderate if PaO₂ is between 56 and 69 mmHg. Although current guidelines consider LTOT only in patients with severe resting hypoxemia, many COPD patients with moderate to severe disease experience moderate hypoxemia at rest or during special circumstances, such as while sleeping or exercising. The efficacy of LTOT in these patients who do not meet the actual recommendations is still a matter of debate, and extensive research is still ongoing to understand the possible benefits of LTOT for survival and/or functional outcomes such as the sensation of dyspnea, exacerbation frequency, hospitalizations, exercise capacity, and quality of life. Despite its frequent use, the administration of "palliative" oxygen does not seem to improve dyspnea except for delivery with high-flow humidified oxygen. This narrative review will focus on current evidence for the effects of LTOT in the presence of moderate hypoxemia at rest, during sleep, or during exercise in COPD.

Clinical, physiologic, and radiographic factors contributing to development of hypoxemia in moderate to severe COPD: a cohort study

Background

Hypoxemia is a major complication of COPD and is a strong predictor of mortality. We previously identified independent risk factors for the presence of resting hypoxemia in the COPDGene cohort. However, little is known about characteristics that predict onset of resting hypoxemia in patients who are normoxic at baseline. We hypothesized that a combination of clinical, physiologic, and radiographic characteristics would predict development of resting hypoxemia after 5-years of follow-up in participants with moderate to severe COPD

Methods

We analyzed 678 participants with moderate-to-severe COPD recruited into the COPDGene cohort who completed baseline and 5-year follow-up visits and who were normoxic by pulse oximetry at baseline. Development of resting hypoxemia was defined as an oxygen saturation ≤88% on ambient air at rest during follow-up. Demographic and clinical characteristics, lung function, and radiographic indices were analyzed with logistic regression models to identify predictors of the development of hypoxemia.

Results

Forty-six participants (7%) developed resting hypoxemia at follow-up. Enrollment at Denver (OR 8.30, 95%CI 3.05–22.6), lower baseline oxygen saturation (OR 0.70, 95%CI 0.58–0.85), self-reported heart failure (OR 6.92, 95%CI 1.56–30.6), pulmonary artery (PA) enlargement on computed tomography (OR 2.81, 95%CI 1.17–6.74), and prior severe COPD exacerbation (OR 3.31, 95%CI 1.38–7.90) were independently associated with development of resting hypoxemia. Participants who developed hypoxemia had greater decline in 6-min walk distance and greater 5-year decline in quality of life compared to those who remained normoxic at follow-up.

Conclusions

Development of clinically significant hypoxemia over a 5-year span is associated with comorbid heart failure, PA enlargement and severe COPD exacerbation. Further studies are needed to determine if treatments targeting these factors can prevent new onset hypoxemia.

Trial registration

COPDGene is registered at ClinicalTrials.gov: NCT00608764 (Registration Date: January 28, 2008)

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-016-0331-0) contains supplementary material, which is available to authorized users.

Oxygen for breathlessness in patients with chronic obstructive pulmonary disease who do not qualify for home oxygen therapy

BACKGROUND

Breathlessness is a cardinal symptom of chronic obstructive pulmonary disease (COPD). Long-term oxygen therapy (LTOT) is given to improve survival time in people with COPD and severe chronic hypoxaemia at rest. The efficacy of oxygen therapy for breathlessness and health-related quality of life (HRQOL) in people with COPD and mild or no hypoxaemia who do not meet the criteria for LTOT has not been established.

OBJECTIVES

To determine the efficacy of oxygen versus air in mildly hypoxaemic or non-hypoxaemic patients with COPD in terms of (1) breathlessness; (2) HRQOL; (3) patient preference whether to continue therapy; and (4) oxygen-related adverse events.

SEARCH METHODS

We searched the Cochrane Airways Group Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and Embase, to 12 July 2016, for randomised controlled trials (RCTs). We handsearched the reference lists of included articles.

SELECTION CRITERIA

We included RCTs of the effects of non-invasive oxygen versus air on breathlessness, HRQOL or patient preference to continue therapy among people with COPD and mild or no hypoxaemia (partial pressure of oxygen (PaO₂) > 7.3 kPa) who were not already receiving LTOT. Two review authors independently assessed articles for inclusion in the review.

DATA COLLECTION AND ANALYSIS

Two review authors independently collected and analysed data. We assessed risk of bias by using the Cochrane 'Risk of bias tool'. We pooled effects recorded on different scales as standardised mean differences (SMDs) with 95% confidence intervals (CIs) using random-effects models. Lower SMDs indicated decreased breathlessness and reduced HRQOL. We performed subanalyses and sensitivity analyses and assessed the quality of evidence according to the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach.

MAIN RESULTS

Compared with the previous review, which was published in 2011, we included 14 additional studies (493 participants), excluded one study and included data for meta-analysis of HRQOL. In total, we included in this review 44 studies including 1195 participants, and we included 33 of these (901 participants)in the meta-analysis.We found that breathlessness during exercise or daily activities was reduced by oxygen compared with air (32 studies; 865 participants; SMD -0.34, 95% CI -0.48 to -0.21; I² = 37%; low-quality evidence). This translates to a decrease in breathlessness of about 0.7 points on a 0 to 10 numerical rating scale. In contrast, we found no effect of short-burst oxygen given before exercise (four studies; 90 participants; SMD 0.01, 95% CI -0.26 to 0.28; I² = 0%; low-quality evidence). Oxygen reduced breathlessness measured during exercise tests (25 studies; 442 participants; SMD -0.34, 95% CI -0.46 to -0.22; I² = 29%; moderate-quality evidence), whereas evidence of an effect on breathlessness measured in daily life was limited (two studies; 274 participants; SMD -0.13, 95% CI, -0.37 to 0.11; I² = 0%; low-quality evidence).Oxygen did not clearly affect HRQOL (five studies; 267 participants; SMD 0.10, 95% CI -0.06 to 0.26; I² = 0%; low-quality evidence). Patient preference and adverse events could not be analysed owing to insufficient data.

AUTHORS' CONCLUSIONS

We are moderately confident that oxygen can relieve breathlessness when given during exercise to mildly hypoxaemic and non-hypoxaemic people with chronic obstructive pulmonary disease who would not otherwise qualify for home oxygen therapy. Most evidence pertains to acute effects during exercise tests, and no evidence indicates that oxygen decreases breathlessness in the daily life setting. Findings show that oxygen does not affect health-related quality of life.

Supplemental Oxygen During High-Intensity Exercise Training in Nonhypoxemic Chronic Obstructive Pulmonary Disease

BACKGROUND

Physical exercise training is an evidence-based treatment in chronic obstructive pulmonary disease, and patients' peak work rate is associated with reduced chronic obstructive pulmonary disease mortality. We assessed whether supplemental oxygen during exercise training in nonhypoxemic patients with chronic obstructive pulmonary disease might lead to superior training outcomes, including improved peak work rate.

METHODS

This was a randomized, double-blind, controlled, crossover trial. Twenty-nine patients with chronic obstructive pulmonary disease (aged 63.5 ± 5.9 years; forced expiratory volume in 1 second percent predicted, 46.4 ± 8.6) completed 2 consecutive 6-week periods of endurance and strength training with progressive intensity, which was performed 3 times per week with supplemental oxygen or compressed medical air (flow via nasal cannula: 10 L/min). Each session of electrocardiography-controlled interval cycling lasted 31 minutes and consisted of a warm-up, 7 cycles of 1-minute intervals at 70% to 80% of peak work rate alternating with 2 minutes of active recovery, and final cooldown. Thereafter, patients completed 8 strength-training exercises of 1 set each with 8 to 15 repetitions to failure. Change in peak work rate was the primary study end point.

RESULTS

The increase in peak work rate was more than twice as high when patients exercised with supplemental oxygen compared with medical air (0.16 ± 0.02 W/kg vs 0.07 ± 0.02 W/kg; P < .001), which was consistent with all other secondary study end points related to exercise capacity. The impact of oxygen on peak work rate was 39.1% of the overall training effect, whereas it had no influence on strength gain (P > .1 for all exercises).

CONCLUSIONS

We report that supplemental oxygen in nonhypoxemic chronic obstructive pulmonary disease doubled the effect of endurance training but had no effect on strength gain.

Performance enhancement in chronic obstructive pulmonary disease

Background: Exercise limitation is a hallmark of chronic obstructive pulmonary disease (COPD) and is integral to the associated impaired health status of these patients. The poor exercise tolerance is multifactorial in origin, relating to airflow obstruction, disadvantageous lung mechanics, reduced oxygen delivery and skeletal muscle dysfunction. A number of interventions have been studied to determine whether they can impact on exercise performance. The most evidence-based of these is exercise training, which along with other approaches, both previously investigated and putative, are discussed in this review.

Ambulatory and short-burst oxygen for interstitial lung disease

BACKGROUND

A large subgroup of people with interstitial lung disease (ILD) are normoxic at rest, but rapidly desaturate on exertion. This can limit exercise capacity and worsen dyspnoea. The use of ambulatory or short-burst oxygen when mobilising or during other activities, may improve exercise capacity and relieve dyspnoea.

OBJECTIVES

To determine the effects of ambulatory and short-burst oxygen therapy, separately, on exercise capacity, dyspnoea and quality of life in people who have interstitial lung disease (ILD), particularly those with idiopathic pulmonary fibrosis (IPF).

SEARCH METHODS

We conducted searches in the Cochrane Airways Group Specialised Register (all years to May 2016), Cochrane Central Register of Controlled Trials (CENTRAL) (all years to May 2016), MEDLINE (Ovid) (1950 to 4th May 2016) and EMBASE (Ovid) (1974 to 4th May 2016). We also searched the reference lists of relevant studies, international clinical trial registries and respiratory conference abstracts for studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs that compared ambulatory or short-burst oxygen with a control group in people with ILD of any origin.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion and assessed risk of bias in the included studies. We extracted data from included studies using a prepared checklist, including study characteristics and results. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria to assess the quality of the included studies.

MAIN RESULTS

Three studies (including 98 participants, all of whom had IPF) met the inclusion criteria of this review. These studies were conducted in hospital respiratory physiology laboratories. Two studies did not demonstrate any beneficial effect of supplemental oxygen on exercise capacity or exertional dyspnoea. Neither of these studies titrated oxygen requirements to prevent ongoing exertional desaturation. One study showed an increase in exercise capacity as assessed by endurance time with supplemental oxygen. We did not identify any studies that examined the effect of ambulatory oxygen on health-related quality of life, survival, costs or time to exacerbation or hospitalisation. No study reported any adverse events. The quality of evidence for all three studies, as assessed by GRADE criteria, was low.

AUTHORS' CONCLUSIONS

This review found no evidence to support or refute the use of ambulatory or short burst oxygen in ILD due to the limited number of included studies and data. Further research is needed to examine the role of this treatment.

Outdoor activity and performance status as predictors of survival in hypoxaemic chronic obstructive pulmonary disease (COPD)

Background: Performance status has been associated with survival in hypoxaemic chronic obstructive pulmonary disease (COPD) patients on long-term oxygen therapy.

Objective: To determine whether self-reported outdoor activity and performance status are independent predictors of survival in hypoxaemic COPD patients on long-term oxygen therapy.

Design, subjects and main measure: In a prospective design, survival over an eight-year period was studied in 226 Danish patients on long-term oxygen therapy. They were subdivided according to self-reported mobility (&plusmn;outdoor activity) and World Health Organization (WHO) performance status (score 0-4).

Results: A total of 148 patients (65.5%) reported outdoor activity. Compared to the immobile patients, those reporting outdoor activity had higher performance status, higher body mass index and lower duration of oxygen administration. In multivariate analyses adjusting for body mass index, gender and age, both poor performance status and lack of outdoor activity were associated with poor survival (p-levels 0.006 and 0.045, respectively). Lack of outdoor activity was associated with increased mortality (relative risk (RR) and 95% confidence interval of dying was 1.39 (1.01-1.91)) and significantly higher risk was found among those with age in the youngest tertile (less than 66.4 years), the relative risk of dying was 2.18 (1.20-3.95).

Conclusions: This study shows that self-reported performance status and outdoor activity are independent predictors of survival in hypoxaemic COPD patients on long-term oxygen therapy. However, our study suggests that in the most elderly patients, outdoor activity does not predicting survival. Further studies are needed to determine whether interventions that facilitate outdoor activity (e.g., pulmonary rehabilitation) have an effect on survival in this group of patients.

Ambulatory Oxygen for Exercise-Induced Desaturation and Dyspnea in Chronic Obstructive Pulmonary Disease (COPD): Systematic Review and Meta-Analysis

Introduction: Ambulatory oxygen therapy is indicated in patients that use long term oxygen therapy (LTOT) and current guidelines suggest its use in patients who exhibit exertional desaturation if there is a demonstrable improvement in exercise capacity. Evidence for this is largely derived from single assessment studies which have shown clear benefit in this setting when oxygen versus air is used. The long term effects, however, of ambulatory oxygen therapy in this particular group of patients is controversial. Methods: We conducted a systematic review of published literature from 1980 to June 2014 for trials in which ambulatory oxygen was compared to placebo in chronic obstructive pulmonary disease (COPD) patients not on LTOT. We also reviewed the effectiveness of devices delivering ambulatory oxygen. Outcome measures were focused towards exercise capacity, Borg scores and the ability of the delivery devices to maintain oxygen saturations on exercise. Results: Twenty three studies (620 patients) were included in the review. Nine studies evaluated the clinical effectiveness of ambulatory oxygen and 14 studies evaluated the impact of the delivery devices. Ambulatory oxygen had no statistical effect on improving exercise capacity when assessed by the 6-minute walk test (6MWT) or the endurance shuttle walk test (ESWT);p=0.44 and p=0.29 respectively. End of test Borg scores showed no statistical improvement with ambulatory oxygen therapy during 6MWT (p=0.68). Oxygen conserving devices significantly improved oxygen saturations on exercise compared with continuous flow nasal cannulae (p=0.04). Conclusion: Ambulatory oxygen therapy has limited long term benefit in improving functional exercise capacity or Borg dyspnea scores.

Eligibility for home oxygen programs and funding across Canada

BACKGROUND

In Canada, although medical insurance is generally universal, significant differences exist in the provision of home oxygen therapy across the country.

OBJECTIVE

To systematically compare the terms of reference for home oxygen across Canada, with a focus on the clinical inclusion criteria to the programs.

METHODS

The authors searched the terms of reference of the 10&nbsp;Canadian provinces and three territories, focusing on general eligibility criteria for home oxygen (including blood gas criteria, and eligibility criteria for ambulatory and nocturnal oxygen), and compared the eligibility criteria to the widely accepted criteria of the Nocturnal Oxygen Therapy Trial (NOTT) trial, the clinical recommendations of the Canadian Thoracic Society and the results of Cochrane reviews.

RESULTS

The terms of reference for nine provinces were retrieved. All jurisdictions have similar criteria for long-term oxygen therapy, with slight differences in the thresholds of prescription and the clinical criteria defining 'pulmonary hypertension' or 'cor pulmonale'. The use of oxyhemoglobin saturation as a criterion for funding is inconsistent. All nine provinces fund nocturnal oxygen, all with different clinical criteria. Funding for portable oxygen widely varies across provinces, whether the ambulatory equipment is offered to patients on long-term oxygen therapy or to those who have isolated exercise-induced desaturation. The terms of reimbursement are very heterogeneous.

CONCLUSIONS

Heterogeneity exists in the criteria for eligibility to home oxygen programs and funding across Canada. Terms of prescription and reimbursement of oxygen are not necessarily supported by available evidence from the current literature in several Canadian jurisdictions.

Oxygen therapy for COPD

Chronic obstructive pulmonary disease (COPD) is a leading cause of disability and death globally, characterised by progressive breathlessness, loss of function and, in its later stages, chronic hypoxaemia. Long-term continuous oxygen therapy increases life expectancy in patients with severe resting hypoxaemia. However, there are few data to support the use of oxygen in patients with only mild hypoxaemia and more research is required to determine any benefits of oxygen supplementation in COPD in such individuals.

An official European Respiratory Society/American Thoracic Society technical standard: field walking tests in chronic respiratory disease

Field walking tests are commonly employed to evaluate exercise capacity, assess prognosis and evaluate treatment response in chronic respiratory diseases. In recent years, there has been a wealth of new literature pertinent to the conduct of the 6-min walk test (6MWT), and a growing evidence base describing the incremental and endurance shuttle walk tests (ISWT and ESWT, respectively). The aim of this document is to describe the standard operating procedures for the 6MWT, ISWT and ESWT, which can be consistently employed by clinicians and researchers. The Technical Standard was developed by a multidisciplinary and international group of clinicians and researchers with expertise in the application of field walking tests. The procedures are underpinned by a concurrent systematic review of literature relevant to measurement properties and test conduct in adults with chronic respiratory disease. Current data confirm that the 6MWT, ISWT and ESWT are valid, reliable and responsive to change with some interventions. However, results are sensitive to small changes in methodology. It is important that two tests are conducted for the 6MWT and ISWT. This Technical Standard for field walking tests reflects current evidence regarding procedures that should be used to achieve robust results.

An official systematic review of the European Respiratory Society/American Thoracic Society: measurement properties of field walking tests in chronic respiratory disease

This systematic review examined the measurement properties of the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT) in adults with chronic respiratory disease.

Studies that report the evaluation or use of the 6MWT, ISWT or ESWT were included. We searched electronic databases for studies published between January 2000 and September 2013.

The 6-min walking distance (6MWD) is a reliable measure (intra-class correlation coefficients ranged from 0.82 to 0.99 in seven studies). There is a learning effect, with greater distance walked on the second test (pooled mean improvement of 26 m in 13 studies). Reliability was similar for ISWT and ESWT, with a learning effect also evident for ISWT (pooled mean improvement of 20 m in six studies). The 6MWD correlates more strongly with peak work capacity (r=0.59–0.93) and physical activity (r=0.40–0.85) than with respiratory function (r=0.10–0.59). Methodological factors affecting 6MWD include track length, encouragement, supplemental oxygen and walking aids. Supplemental oxygen also affects ISWT and ESWT performance. Responsiveness was moderate to high for all tests, with greater responsiveness to interventions that included exercise training.

The findings of this review demonstrate that the 6MWT, ISWT and ESWT are robust tests of functional exercise capacity in adults with chronic respiratory disease.

Ambulatory oxygen for people with chronic obstructive pulmonary disease who are not hypoxaemic at rest

BACKGROUND

People with chronic obstructive pulmonary disease (COPD) often become transiently hypoxaemic (low oxygen levels in blood) on exercise, necessitating oxygen therapy to improve breathlessness and exercise capacity and to reduce disability. Ambulatory oxygen therapy refers to provision of oxygen therapy during exercise and activities of daily living. Ambulatory oxygen therapy is often used by patients on long-term oxygen therapy (LTOT) during exercise or by non-LTOT users with or without resting hypoxaemia when they show evidence of exercise de-saturation and demonstrate improvement in exercise capacity with supplemental oxygen.

OBJECTIVES

To determine the longer-term efficacy of ambulatory oxygen therapy only in patients with COPD who do not meet the criteria for LTOT, with respect to improvement in exercise capacity, mortality, quality of life and other relevant measures of improvement.

SEARCH METHODS

The Cochrane Airways Group Specialised Register, including MEDLINE, EMBASE and CINAHL, was searched. Online clinical trial registers, including Controlled Clinical Trials (www.controlled-trials.com), government registries (clinicaltrials.gov) and World Health Organization (WHO) registries (www.who.int/trialsearch), were screened for ongoing and recently completed studies. Bibliographies of included studies were searched for additional trials that may meet the inclusion criteria and were not retrieved by the above search strategy. Authors of identified trials were contacted to provide other published and unpublished studies. Searches were current as of November 2012.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that compare ambulatory oxygen therapy provided through portable oxygen cylinders/battery-powered devices or liquid oxygen canisters versus placebo air cylinders, usual medical care or co-intervention in study participants with COPD who did not meet criteria for LTOT.

DATA COLLECTION AND ANALYSIS

We used standard methods as expected by The Cochrane Collaboration.

MAIN RESULTS

Four studies met the inclusion criteria (331 participants), with two studies producing a statistically and clinically significant benefit in favour of the intervention for dyspnoea post exercise.The quality of life domain for all four included studies produced a statistically significant benefit for the subcategories of dyspnoea and fatigue, in favour of the oxygen group (dyspnoea mean difference (MD) 0.28, 95% confidence interval (CI) 0.10 to 0.45; P value 0.002; fatigue MD 0.17, 95% CI 0.04 to 0.31; P value 0.009). No evidence of any effect was reported for survival, and limited benefits were observed for exercise capacity (as measured by step test and distance walk test), with one study showing a statistically significant improvement in the number of steps taken in the oxygen group for group N-of-1 studies only. No other statistically significant benefits were observed for exercise capacity among the other trials or individual N-of-1 studies.

AUTHORS' CONCLUSIONS

In patients with COPD with moderate hypoxia, current evidence on ambulatory oxygen therapy reveals improvements in dyspnoea post exercise and in the dyspnoea and fatigue domain of quality of life. However, evidence for the clinical utility and effectiveness of ambulatory oxygen in improving mortality and exercise capacity was not evident in this review. Methodologically rigorous RCTs with sufficient power to detect a difference are required to investigate the role of ambulatory oxygen in the management of COPD.

Outcome measures for palliative oxygen therapy: relevance and practical utility

Dyspnea is a common symptom in many advanced malignant and non-malignant diseases and often is refractory to the usual therapies. In such circumstances palliative care approaches are necessary and among them palliative care oxygen therapy can be applied although currently its effectiveness is rather uncertain. Palliative oxygen therapy can be given on either continuous basis or on demand. Often the continuous palliative oxygen therapy is seen as long-term oxygen therapy although their aims are rather different. Palliative oxygen therapy was evaluated in populations with mixed underlying diseases, with outcome measures not only the most appropriate for the setting and therefore these limitations might have influenced the overall perceived therapeutic benefit. Therefore an evaluation of this method in subsets defined based on the etiology and pathogenic mechanisms and with appropriate outcome measures would help to better define the criteria for its indication and would increase its acceptability.

Exercise endurance in chronic obstructive pulmonary disease patients at an altitude of 2640 meters breathing air and oxygen (FIO2 28% and 35%): a randomized crossover trial

BACKGROUND

At Bogota's altitude (2640 m), the lower barometric pressure (560 mmHg) causes severe hypoxemia in COPD patients, limiting their exercise capacity. The aim was to compare the effects of breathing oxygen on exercise tolerance.

METHODS

In a blind, crossover clinical study, 29 COPD patients (FEV1 42.9 ± 11.9%) breathed room air (RA) or oxygen (FIO2 28% and 35%) during three treadmill exercise tests at 70% of their maximal capacity in a randomized order. Endurance time (ET), inspiratory capacity (IC), arterial blood gases and lactate were compared.

RESULTS

At the end of the exercise breathing RA, the ET was 9.7 ± 4.2 min, the PaO2 46.5 ± 8.2 mmHg, the lactate increased and the IC decreased. The oxygen significantly increased the ET (p < 0.001), without differences between 28% (16.4 ± 6.8 min) and 35% (17.6 ± 7.0 min) (p = 0.22). Breathing oxygen, there was an increase in the PaO2 and SaO2, higher with FIO2 35%, and a decrease in the lactate level. At "isotime" (ET at RA), with oxygen, the SpO2, the oxygen pulse and the IC were higher and the heart rate lower than breathing RA (p < 0.05).

CONCLUSION

Oxygen administration for COPD patients in Bogotá significantly increased ET by decreased respiratory load, improved cardiovascular performance and oxygen transport. The higher increases of the PaO2 and SaO2 with 35% FIO2 did not represent a significant advantage in the ET. This finding has important logistic and economic implications for oxygen use in rehabilitation programs of COPD patients at the altitude of Bogotá and similar altitudes.

Synthesis, grading, and presentation of evidence in guidelines: article 7 in Integrating and coordinating efforts in COPD guideline development. An official ATS/ERS workshop report

INTRODUCTION

Professional societies, like many other organizations around the world, have recognized the need to use more rigorous processes to ensure that health care recommendations are informed by the best available research evidence. This is the seventh of a series of 14 articles that were prepared to advise guideline developers in respiratory and other diseases on approaches for guideline development. This article focuses on synthesizing, rating, and presenting evidence in guidelines.

METHODS

In this review we addressed the following questions. (1) What evidence should guideline panels use to inform their recommendations? (2) How should they rate the quality of the evidence they use? (3) How should they grade evidence regarding diagnostic tests? (4) What should they do when quality of evidence differs across outcomes? (5) How should they present the evidence in a guideline? We did not conduct systematic reviews ourselves. We relied on prior evaluations of electronic databases and systematic reviews suggesting that the Grades of Recommendation, Assessment, Development and Evaluation Working Group (GRADE) approach includes the desired features of a system for grading quality of evidence, including provision of models for presenting evidence for guideline panels, and for the consumers of practice guidelines. This article describes the GRADE approach to grading the quality of evidence and presenting evidence. Available evidence, the practice of leading guideline developers, and workshop discussions provide the basis for our conclusions.

RESULTS AND DISCUSSION

GRADE rates the quality of evidence for each outcome across studies rather than for each study. In the GRADE approach randomized trials start as high-quality evidence and observational studies as low-quality evidence, but both can be rated down or up. Five factors may lead to rating down the quality of evidence: study limitations or risk of bias, inconsistency of results, indirectness of evidence, imprecision, and publication bias. Three factors may lead to rating up the quality of evidence from observational studies: large magnitude of effect, dose-response gradient, and situations in which all plausible confounders would decrease an apparent treatment effect, or would create a spurious effect when results suggest no effect. GRADE suggests use of evidence profiles that provide a comprehensive way to display the key evidence relevant to a clinical question. Guideline developers who follow this structure will find the transparency of their recommendations markedly enhanced.

The long-term effect of ambulatory oxygen in normoxaemic COPD patients

Aim: To study the long-term benefits of ambulatory oxygen (AO) in combination with pulmonary rehabilitation (PR) in chronic obstructive pulmonary disease (COPD) patients experiencing exertional desaturation. Patients and methods: Normoxaemic COPD who participated in outpatient PR and desaturated >4% and <90% during endurance shuttle walk test (ESWT) were randomised to control ( n = 23) or AO 2 L/min from a portable oxygen concentrator ( n = 22) to be used during exercise. PR consisted of supervised training for 20 weeks combined with unsupervised daily training at home followed by 13 weeks without supervised training. Results: Only 45 of 165 eligible patients wanted to participate. Mean forced expiratory volume in 1 s = 32% ( SD 13.8) and Medical Research Council (MRC) = 4.5 (3–5). Supplemental oxygen improved oxygen saturation during ESWT by 2.3% (95% CI: 1.2%–3.5%; p < 0.001). In the study period of 33 weeks, 10 and 6 patients withdrew from the AO group and control group, respectively. Patients spent an average of 7.9 h/week on oxygen. PR improved ESWT by 18,076 s (95% CI: 101–258 s; p < 0.001) and St. George’s Respiratory Questionnaire (SGRQ) score by 2.6 units (95% CI: 0.1–5.1 s; p = 0.04) after 7 weeks, and these gains remained at 33 weeks of evaluation. There were no differences between the AO group and control group at 33 weeks of evaluation with regard to change in ESWT (223 vs. 241 s; p = 0.32), change in SGRQ (−3.6 vs. −4.5 units, 0.91), and number of patients with acute exacerbation in COPD (AECOPD), hospital admission or dropout (17 of 22 vs. 20 of 23, p = 0.59). Conclusions: AO seems not to provide additional beneficial effects in patients with COPD participating in pulmonary rehabilitation and experiencing exertional desaturation without severe resting hypoxaemia.

Managing dyspnea in patients with advanced chronic obstructive pulmonary disease: a Canadian Thoracic Society clinical practice guideline

Dyspnea is a cardinal symptom of chronic obstructive pulmonary disease (COPD), and its severity and magnitude increases as the disease progresses, leading to significant disability and a negative effect on quality of life. Refractory dyspnea is a common and difficult symptom to treat in patients with advanced COPD. There are many questions concerning optimal management and, specifically, whether various therapies are effective in this setting. The present document was compiled to address these important clinical issues using an evidence-based systematic review process led by a representative interprofessional panel of experts. The evidence supports the benefits of oral opioids, neuromuscular electrical stimulation, chest wall vibration, walking aids and pursed-lip breathing in the management of dyspnea in the individual patient with advanced COPD. Oxygen is recommended for COPD patients with resting hypoxemia, but its use for the targeted management of dyspnea in this setting should be reserved for patients who receive symptomatic benefit. There is insufficient evidence to support the routine use of anxiolytic medications, nebulized opioids, acupuncture, acupressure, distractive auditory stimuli (music), relaxation, handheld fans, counselling programs or psychotherapy. There is also no evidence to support the use of supplemental oxygen to reduce dyspnea in nonhypoxemic patients with advanced COPD. Recognizing the current unfamiliarity with prescribing and dosing of opioid therapy in this setting, a potential approach for their use is illustrated. The role of opioid and other effective therapies in the comprehensive management of refractory dyspnea in patients with advanced COPD is discussed.

An official American Thoracic Society statement: update on the mechanisms, assessment, and management of dyspnea

BACKGROUND

Dyspnea is a common, distressing symptom of cardiopulmonary and neuromuscular diseases. Since the ATS published a consensus statement on dyspnea in 1999, there has been enormous growth in knowledge about the neurophysiology of dyspnea and increasing interest in dyspnea as a patient-reported outcome.

PURPOSE

The purpose of this document is to update the 1999 ATS Consensus Statement on dyspnea.

METHODS

An interdisciplinary committee of experts representing ATS assemblies on Nursing, Clinical Problems, Sleep and Respiratory Neurobiology, Pulmonary Rehabilitation, and Behavioral Science determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant expertise. The final content of this statement was agreed upon by all members.

RESULTS

Progress has been made in clarifying mechanisms underlying several qualitatively and mechanistically distinct breathing sensations. Brain imaging studies have consistently shown dyspnea stimuli to be correlated with activation of cortico-limbic areas involved with interoception and nociception. Endogenous and exogenous opioids may modulate perception of dyspnea. Instruments for measuring dyspnea are often poorly characterized; a framework is proposed for more consistent identification of measurement domains.

CONCLUSIONS

Progress in treatment of dyspnea has not matched progress in elucidating underlying mechanisms. There is a critical need for interdisciplinary translational research to connect dyspnea mechanisms with clinical treatment and to validate dyspnea measures as patient-reported outcomes for clinical trials.

An official American Thoracic Society statement: update on the mechanisms, assessment, and management of dyspnea

BACKGROUND

Dyspnea is a common, distressing symptom of cardiopulmonary and neuromuscular diseases. Since the ATS published a consensus statement on dyspnea in 1999, there has been enormous growth in knowledge about the neurophysiology of dyspnea and increasing interest in dyspnea as a patient-reported outcome.

PURPOSE

The purpose of this document is to update the 1999 ATS Consensus Statement on dyspnea.

METHODS

An interdisciplinary committee of experts representing ATS assemblies on Nursing, Clinical Problems, Sleep and Respiratory Neurobiology, Pulmonary Rehabilitation, and Behavioral Science determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant expertise. The final content of this statement was agreed upon by all members.

RESULTS

Progress has been made in clarifying mechanisms underlying several qualitatively and mechanistically distinct breathing sensations. Brain imaging studies have consistently shown dyspnea stimuli to be correlated with activation of cortico-limbic areas involved with interoception and nociception. Endogenous and exogenous opioids may modulate perception of dyspnea. Instruments for measuring dyspnea are often poorly characterized; a framework is proposed for more consistent identification of measurement domains.

CONCLUSIONS

Progress in treatment of dyspnea has not matched progress in elucidating underlying mechanisms. There is a critical need for interdisciplinary translational research to connect dyspnea mechanisms with clinical treatment and to validate dyspnea measures as patient-reported outcomes for clinical trials.

Symptomatic oxygen for non-hypoxaemic chronic obstructive pulmonary disease

BACKGROUND

Dyspnoea is a common symptom in chronic obstructive pulmonary disease (COPD). People who are hypoxaemic may be given long-term oxygen relief therapy (LTOT) to improve their life expectancy and quality of life. However, the symptomatic benefit of home oxygen therapy in mildly or non-hypoxaemic people with COPD with dyspnoea who do not meet international funding criteria for LTOT (PaO(2)< 55 mmHg or other special cases) is unknown.

OBJECTIVES

To determine the efficacy of oxygen versus medical air for relief of subjective dyspnoea in mildly or non-hypoxaemic people with COPD who would not otherwise qualify for home oxygen therapy. The main outcome was patient-reported dyspnoea and secondary outcome was exercise tolerance.

SEARCH STRATEGY

We searched the Cochrane Airways Group Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE, to November 2009, to identify randomised controlled trials. We handsearched reference lists of included articles.

SELECTION CRITERIA

We only included randomised controlled trials of oxygen versus medical air in mildly or non-hypoxaemic people with COPD. Two review authors independently assessed articles for inclusion.

DATA COLLECTION AND ANALYSIS

One review author completed data extraction and methodological quality assessment. A second review author then over-read evidence tables to assess for accuracy.

MAIN RESULTS

Twenty-eight trials on 702 patients met the criteria for inclusion; 18 trials (431 participants) were included in the meta-analysis. Oxygen reduced dyspnoea with a standardised mean difference (SMD) of -0.37 (95% confidence interval (CI) -0.50 to -0.24, P < 0.00001). We observed significant heterogeneity.

AUTHORS' CONCLUSIONS

Oxygen can relieve dyspnoea in mildly and non-hypoxaemic people with COPD who would not otherwise qualify for home oxygen therapy. Given the significant heterogeneity among the included studies, clinicians should continue to evaluate patients on an individual basis until supporting data from ongoing, large randomised controlled trials are available.

[Efficacy and patterns of ambulatory oxygen usage - experience of a university hospital]

AIMS

To determine patterns of ambulatory oxygen (AO) use among patients with chronic obstructive pulmonary disease (COPD) and interstitial lung diseases, and analyze the effects of this therapy on daily activities and quality of life (QoL).

PATIENTS AND METHODS

We included 37 consecutive adult patients on AO by liquid O(2) for more than three months prescribed by hospital pulmonologists. The acute response to O(2) was evaluated through the standardized 6-minutes walk test (6MWT) and the Borg dyspnea scale during the O(2) pre-intervention trial. Time spent away from home, compliance, side effects and QoL (SF-36 v1 questionnaire) were evaluated by a telephone interview during the follow-up period. Time spent away from home and QoL comparisons after and before the intervention were assessed retrospectively.

RESULTS

COPD was the most frequent diagnosis (54%), and 29 (78%) patients were already on long-term oxygen therapy. In relation to the acute response to O(2) evaluated through the 6MWT, there were significant improvements in the distance walked (p<0.001), in resting SatO(2) (p<0.001), in minimal SatO(2) (p<0.001), and in percentage of desaturation (p=0.002), independently of the diagnosis. No differences were observed in Borg dyspnea scale. AO was used for a mean of 4.1h/day. Patients spent fewer hours per day away from home after AO treatment (3.5h vs. 5.0h, p<0.025). Six patients (16%) were not compliant to the prescription, and 54% mentioned side effects. We verified low scores in almost all of the sub-domains of SF-36 QoL questionnaire, with a significant improvement noted only in role emotional (p=0.032). Improvement in health global state was described by 49% of patients.

CONCLUSIONS

Acute improvement in 6MWT parameters was not predictive of enhancement of outdoor activities and QoL with AO. More detailed studies are needed to achieve evidence based AO benefits.

A crossover study of short burst oxygen therapy (SBOT) for the relief of exercise-induced breathlessness in severe COPD

BACKGROUND

Previous small studies suggested SBOT may be ineffective in relieving breathlessness after exercise in COPD.

METHODS

34 COPD patients with FEV1 <40% predicted and resting oxygen saturation ≥93% undertook an exercise step test 4 times. After exercise, patients were given 4 l/min of oxygen from a simple face mask, 4 l/min air from a face mask (single blind), air from a fan or no intervention.

RESULTS

Average oxygen saturation fell from 95.0% to 91.3% after exercise. The mean time to subjective recovery was 3.3 minutes with no difference between treatments. The mean Borg breathlessness score was 1.5/10 at rest, rising to 5.1/10 at the end of exercise (No breathlessness = 0, worst possible breathlessness = 10). Oxygen therapy had no discernable effect on Borg scores even for 14 patients who desaturated below 90%. 15 patients had no preferred treatment, 7 preferred oxygen, 6 preferred the fan, 3 preferred air via a mask and 3 preferred room air.

CONCLUSIONS

This study provides no support for the idea that COPD patients who are not hypoxaemic at rest derive noticeable benefit from oxygen therapy after exercise. Use of air from a mask or from a fan had no apparent physiological or placebo effect.

Oxygen therapy for patients with COPD: current evidence and the long-term oxygen treatment trial

Long-term use of supplemental oxygen improves survival in patients with COPD and severe resting hypoxemia. However, the role of oxygen in symptomatic patients with COPD and more moderate hypoxemia at rest and desaturation with activity is unclear. The few long-term reports of supplemental oxygen in this group have been of small size and insufficient to demonstrate a survival benefit. Short-term trials have suggested beneficial effects other than survival in patients with COPD and moderate hypoxemia at rest. In addition, supplemental oxygen appeared to improve exercise performance in small short-term investigations of patients with COPD and moderate hypoxemia at rest and desaturation with exercise, but long-term trials evaluating patient-reported outcomes are lacking. This article reviews the evidence for long-term use of supplemental oxygen therapy and provides a rationale for the National Heart, Lung, and Blood Institute Long-term Oxygen Treatment Trial. The trial plans to enroll subjects with COPD with moderate hypoxemia at rest or desaturation with exercise and compare tailored oxygen therapy to no oxygen therapy.