Effects of supplemental oxygen during activity in patients with advanced COPD without severe resting hypoxemia

Treatment Recommendation for Dyspnea in Patients with Advanced Disease: Revised Clinical Guidelines from the Japanese Society for Palliative Medicine

Dyspnea is one of the most common and distressing symptoms in patients with cancer and noncancer advanced diseases. The Japanese Society for Palliative Medicine revised previous guidelines for the management of respiratory symptoms in patients with cancer and newly developed clinical guidelines for managing dyspnea in patients with advanced disease, based on the result of systematic reviews for each clinical question and consensus among experts. We describe the recommendations of the guidelines as well as provide insights into the reasoning behind the recommendations and their development process. There has been a paucity of evidence regarding the interventions for dyspnea in patients with advanced disease. Thus, more clinical research that includes not only randomized controlled trials but also real-world observational studies is warranted.

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.

Genotype Score for Iron Status Is Associated with Muscle Fiber Composition in Women

Human muscle fiber composition is heterogeneous and mainly determined by genetic factors. A previous study reported that experimentally induced iron deficiency in rats increases the proportion of fast-twitch muscle fibers. Iron status has been reported to be affected by genetic factors. As the TMPRSS6 rs855791 T/C and HFE rs1799945 C/G polymorphisms are strongly associated with iron status in humans, we hypothesized that the genotype score (GS) based on these polymorphisms could be associated with the muscle fiber composition in humans. Herein, we examined 214 Japanese individuals, comprising of 107 men and 107 women, for possible associations of the GS for iron status with the proportion of myosin heavy chain (MHC) isoforms (I, IIa, and IIx) as markers of muscle fiber composition. No statistically significant correlations were found between the GS for iron status and the proportion of MHC isoforms in all participants. When the participants were stratified based on sex, women showed positive and negative correlations of the GS with MHC-IIa (age-adjusted p = 0.020) and MHC-IIx (age-adjusted p = 0.011), respectively. In contrast, no correlation was found in men. In women, a 1-point increase in the GS was associated with 2.42% higher MHC-IIa level and 2.72% lower MHC-IIx level. Our results suggest that the GS based on the TMPRSS6 rs855791 T/C and HFE rs1799945 C/G polymorphisms for iron status is associated with muscle fiber composition in women.

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

Standardization of the 6-min walk test in clinical trials of idiopathic pulmonary fibrosis

The 6-min walk test (6MWT) is an important measure of functional capacity in idiopathic pulmonary fibrosis (IPF) and has been an endpoint of several IPF clinical trials. However, current guidance for the 6MWT offers insufficient advice on standardization, particularly oxygen supplementation, for clinical trials. Three physicians experienced with the 6MWT and IPF developed a standardized protocol for the 6MWT based on existing clinical guidelines and published literature. The protocol comprises guidance on test conditions, pre-defined parameters to measure at specified timepoints, and step-by-step instructions on conducting the test. The standardized test will be evaluated in the large-scale phase 3 ISABELA trials (NCT03711162; NCT03733444). The test is conducted indoors, using standardized equipment, along a flat, straight, 30-m unobstructed corridor; tests for each individual are performed by the same administrators at the same time of day; warm-up prior to testing is prohibited; supplemental oxygen tanks are permitted and moved by the patient in the same manner for each test; precise wording is used to instruct and encourage patients. Contraindications and stopping criteria are specified. Key assessments include: 6-min walk distance, distance walked at 1 and 3 min, the Borg CR10 scale, heart rate, blood pressure, and oxygen desaturation levels. A standardized 6MWT for IPF will enable more reliable comparisons between clinical trials and limit variability, optimizing use as an endpoint. Application of the standardized 6MWT in the ISABELA program will allow its correlation with other clinically important endpoints and may lead to novel composite endpoints for use in future trials. Submission category: Study Design, Statistical Design, Study Protocols. Submission classifications: Clinical study methodology; Clinical trial design; Clinical trials; Pulmonary disease; Pulmonary disease clinical trial; Respiratory medicine.

An update on pulmonary rehabilitation techniques for patients with chronic obstructive pulmonary disease

Introduction: Pulmonary rehabilitation (PR) is one of the core components in the management of patients with chronic obstructive pulmonary disease (COPD). In order to achieve the maximal level of independence, autonomy, and functioning of the patient, targeted therapies and interventions based on the identification of physical, emotional and social traits need to be provided by a dedicated, interdisciplinary PR team.Areas covered: The review discusses cardiopulmonary exercise testing in the selection of different modes of training modalities. Neuromuscular electrical stimulation as well as gait assessment and training are discussed as well as add-on therapies as oxygen, noninvasive ventilator support or endoscopic lung volume reduction in selected patients. The potentials of pulsed inhaled nitric oxide in patients with underlying pulmonary hypertension is explored as well as nutritional support. The impact of sleep quality on outcomes of PR is reviewed.Expert opinion: Individualized, comprehensive intervention based on thorough assessment of physical, emotional, and social traits in COPD patients forms a continuous challenge for health-care professionals and PR organizations in order to dynamically implement and adapt these strategies based on dynamic, more optimal understanding of underlying pathophysiological mechanisms.

Determination of whether supplemental oxygen therapy is beneficial during exercise training in patients with COPD: A systematic review and meta-analysis

Exercise training is an integral component of the pulmonary rehabilitation program for patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to systematically search the published literature and analyze the evidence on the efficacy of supplemental oxygen in improving outcomes during exercise training in patients with COPD. The PubMed, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL) and Google scholar databases were searched electronically for articles in the English language published up to May, 2019. In total, 7 trials were included in this systematic review and meta-analysis. There was considerable heterogeneity amongst the included studies. Meta-analysis indicated no significant difference in power (random: MD = −2.38; 95% CI, −5.79 to 1.03; P=0.86) and maximum energy expenditure (VO₂ max) (random: MD = −0.01; 95% CI, −0.06 to 0.07; P=0.45) between the oxygen and control groups on maximal exercise testing. Qualitative analysis of the included studies revealed no benefits of supplemental oxygen in improving exercise capacity and dyspnea scores. Data on the quality of life assessed by the Chronic Respiratory Disease Questionnaire was pooled for 95 participants in the study group and 91 participants in the control group. The results indicated no beneficial effects of supplemental oxygen in improving quality of life outcomes (random: MD = −0.09; 95% CI, −0.16 to −0.01; P=0.59). On the whole, the findings of this study indicate that supplemental oxygen during the exercise training of patients with COPD does not improve exercise capacity, dyspnea scores and quality of life. However, the quality of the evidence is weak. Multi-center randomized controlled trials with homogenous methodology and intervention are required to provide stronger evidence on this subject.

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.

Oxygen compared to air during exercise training in COPD with exercise-induced desaturation

Almost half the patients referred to pulmonary rehabilitation with chronic obstructive pulmonary disease (COPD) desaturate during exercise. Although oxygen supplementation may ameliorate oxygen desaturation, the effects on outcomes of exercise training have not been rigorously evaluated. This study aimed to determine whether supplemental oxygen during exercise training was more effective than medical air in improving exercise capacity and health-related quality of life (HRQoL) in people with COPD.People with COPD who demonstrated oxygen desaturation <90% during the 6-min walk test were recruited to this multicentre trial with randomisation (independent, concealed allocation) to either an Oxygen group or Air group, blinding (participants, exercise trainers and European Respiratory Journal assessors) and intention-to-treat analysis. Both groups received the respective gas from concentrators via nasal prongs at 5 L·min^-1 during exercise training consisting of treadmill and cycle exercise, three times per week for 8 weeks. Primary outcomes were the endurance shuttle walk test (ESWT) time and Chronic Respiratory Disease Questionnaire (CRQ)-Total score.111 participants (60 males), mean±sd age 69±7 years, with moderate to severe COPD were recruited and 97 completed (Oxygen group n=52; Air group n=45). At the end of the 8-week training programme there were no between-group differences in change in ESWT (mean difference 15 s (95% CI -106-136 s) or change in CRQ-Total (0.0 points (95% CI -0.3-0.3 points)). Within-group changes at end-training were significant for ESWT and CRQ-Total (all p<0.01).Exercise capacity and HRQoL improved in both groups, with no greater benefit from training with supplemental oxygen than medical air.

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.

Titrating Oxygen Requirements During Exercise: Evaluation of a Standardized Single Walk Test Protocol

BACKGROUND

Oxygen supplementation for exercise-induced hypoxemia is a common clinical practice that improves exercise tolerance. However, we know of no standardized exercise oxygen titration protocol using a single walk test. We report our experience with a protocol developed in our laboratory.

METHODS

Our protocol is based on the 6-min walk test (6MWT). Pulse oximetry readings (oxygen saturation [Spo₂]) are monitored, and supplemental oxygen is added in 2 L/min increments to keep Spo₂ > 88%. This continues for at least 6 min of walking with the Spo₂ remaining > 88% for at least 3 min. The records of consecutive patients over 4 months undergoing this procedure were reviewed for test performance, oxygen titration results, and adverse events.

RESULTS

Two hundred twenty-two patients were tested; only two prematurely terminated the protocol because of intractable dyspnea. One hundred fifty-six patients (38%) required oxygen supplementation, with the first titration most commonly occurring between 1 and 2 min of walking. Nine of the patients had the first titration after 5 min of walking. The average test duration was 7 min (maximum, 15 min). The average number of titrations was 2.2 (maximum six). Sixteen patients could not maintain Spo₂ > 88% for 3 min despite administration of 15 L/min of supplemental oxygen (maximal dose).

CONCLUSIONS

Our protocol was easily performed as a modification of a standard 6MWT with no serious adverse events. Because it is based on a widely accepted measurement of functional capabilities, and because it determined a stable final oxygen dose for ≥ 3 min of walking in most patients, we believe this protocol can be easily adapted for clinical use.

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.

Short-term Effects of Supplemental Oxygen on 6-Min Walk Test Outcomes in Patients With COPD: A Randomized, Placebo-Controlled, Single-blind, Crossover Trial

BACKGROUND

The acute effect of supplemental oxygen during exercise has been shown to differ largely among patients with COPD. It is unknown what factors influence oxygen response.

METHODS

In a randomized, single-blind fashion, 124 patients with COPD underwent one 6-min walk test on supplemental oxygen (6MWT_O2) and one 6-min walk test on room air after a practice 6-min walk test. Both gases were delivered via standard nasal prongs (2 L/min). For analyses, patients were stratified on the basis of PaO₂ values and compared: (1) 34 patients with resting hypoxemia (HYX); (2) 43 patients with exercise-induced hypoxemia (EIH); and (3) 31 patients with normoxemia (NOX).

RESULTS

Oxygen supplementation resulted in an increase in the 6-min walk distance in the total cohort (27 ± 42 meters; P < .001) and in the subgroups of HYX (37 ± 40 meters; P < .001) and EIH (28 ± 44 meters; P < .001) but not in the NOX subgroup (15 ± 43 meters; P = .065). Forty-two percent of patients with HYX and 47% of patients with EIH improved their 6-min walk distance to a clinically relevant extent (≥ 30 meters) by using oxygen. These oxygen responders were characterized by significantly lower 6-min walk distance using room air compared with patients without a relevant response (306 ± 106 meters vs 358 ± 113 meters; P < .05). Although oxygen saturation was significantly higher during 6MWT_O2 compared with the 6-min walk test on room air in all 3 subgroups, it dropped to < 88% during 6MWT_O2 in 73.5% of patients with HYX.

CONCLUSIONS

In contrast to patients with NOX, patients with HYX and EIH generally benefit from supplemental oxygen by increasing exercise capacity. However, less than one-half of patients reached the threshold of clinically relevant improvements. These oxygen responders were characterized by significantly lower exercise capacity levels.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT00886639; URL: www.clinicaltrials.gov.

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.

A randomised controlled trial of supplemental oxygen versus medical air during exercise training in people with chronic obstructive pulmonary disease: supplemental oxygen in pulmonary rehabilitation trial (SuppORT) (Protocol)

BACKGROUND

Oxygen desaturation during exercise is common in people with chronic obstructive pulmonary disease (COPD). The aim of the study is to determine, in people with COPD who desaturate during exercise, whether supplemental oxygen during an eight-week exercise training program is more effective than medical air (sham intervention) in improving exercise capacity and health-related quality of life both at the completion of training and at six-month follow up.

METHODS/DESIGN

This is a multi-centre randomised controlled trial with concealed allocation, blinding of participants, exercise trainers and assessors, and intention-to-treat analysis. 110 people with chronic obstructive pulmonary disease who demonstrate oxygen desaturation lower than 90 % during the six-minute walk test will be recruited from pulmonary rehabilitation programs in seven teaching hospitals in Australia. People with chronic obstructive pulmonary disease on long term oxygen therapy will be excluded. After confirmation of eligibility and baseline assessment, participants will be randomised to receive either supplemental oxygen or medical air during an eight-week supervised treadmill and cycle exercise training program, three times per week for eight weeks, in hospital outpatient settings. Primary outcome measures will be endurance walking capacity assessed by the endurance shuttle walk test and health-related quality of life assessed by the Chronic Respiratory Disease Questionnaire. Secondary outcomes will include peak walking capacity measured by the incremental shuttle walk test, dyspnoea via the Dyspnoea-12 questionnaire and physical activity levels measured over seven days using an activity monitor. All outcomes will be measured at baseline, completion of training and at six-month follow up.

DISCUSSION

Exercise training is an essential component of pulmonary rehabilitation for people with COPD. This study will determine whether supplemental oxygen during exercise training is more effective than medical air in improving exercise capacity and health-related quality of life in people with COPD who desaturate during exercise.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12612000395831, 5th Jan,2012.

How to carry out a field walking test in chronic respiratory disease

EDUCATIONAL AIMS

To provide recommendations for conducting field walking tests in people with chronic respiratory disease, from the new European Respiratory Society/American Thoracic Society Technical StandardTo provide information to assist in selecting a field walking test in people with chronic respiratory disease.

KEY POINTS

The 6MWT, ISWT and ESWT are valid and reliable tests of functional exercise capacity in people with COPD. The 6MWT is also widely used in other chronic respiratory disorders.There is a learning effect for the 6MWT and ISWT, so two tests must be performed if the tests are being used to measure change over time, with the best distance recorded.The 6MWT is very sensitive to changes in the way it is conducted, including use of encouragement, provision of supplemental oxygen, changes in track layout and length, and use of wheeled walkers. These factors should be held constant when the test is repeated.The 6MWT, ISWT and ESWT are strenuous tests, with cardiorespiratory responses that are similar to those during a maximal incremental exercise test. As a result, the contraindications and precautions for these field walking tests should be the same as for a laboratory-based incremental exercise test.

SUMMARY

The European Respiratory Society (ERS) and American Thoracic Society (ATS) have recently published a Technical Standard which documents the standard operating procedures for the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT). The Technical Standard shows that all three tests are valid and reliable measures of functional exercise capacity in people with chronic respiratory disease and makes recommendations for standardising their performance. Key findings and recommendations of the Technical Standard include: The 6MWT, ISWT and ESWT are strenuous tests which elicit cardiorespiratory responses that are similar to those observed during a maximal incremental exercise test. As a result, the contraindications and precautions for field walking tests should be consistent with those used for a laboratory-based incremental exercise test.There is strong evidence of a learning effect for the 6MWT and ISWT. Two tests should be performed when the 6MWT or ISWT are used to measure change over time.The 6MWT, ISWT and ESWT are responsive to treatment effects in people with chronic respiratory disease, particularly for rehabilitation.The 6MWT is very sensitive to variations in methodology, including use of encouragement, provision of supplemental oxygen, changes in track layout and length, and use of wheeled walkers. These factors should be documented and held constant on repeat testing.The lowest S pO2 recorded during a 6MWT is an important marker of disease severity and prognosis. Continuous pulse oximetry is recommended during the 6MWT, to ensure that the lowest S pO2 is recorded.In adults with chronic respiratory disease, a change in 6-min walk distance of 30 m or more indicates a clinically significant change has occurred.

Exercise-induced desaturation in patients with chronic obstructive pulmonary disease on six-minute walk test

Background and Objectives:

Exercise-induced desaturation (EID) is associated with increased mortality in chronic obstructive pulmonary disease (COPD). However, the relationship of EID with anthropometric and clinical parameters of resting pulmonary function test and six-minute walk test (6MWT) in COPD remains unclear. The study was designed to assess the correlate of EID and to identify various possible predictors of EID in stable normoxemic patients of COPD.

Materials and Methods:

Sixty patients with stable COPD diagnosed and staged as per the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines underwent 6MWT. A drop in standard pulse oximetry (SpO₂) of ≥4% or nadir up to ≤88% was defined as EID. Based on EID during 6MWT, two groups were formed: desaturators (DS) and nondesaturators (NDS). DS and NDS were compared for baseline and clinical characters by the Student's t-test while Pearson and Spearman rho correlation coefficient assessed strength of the association of anthropometric and clinical variables with EID. The predictors of EID were identified by logistic regression and receiver operator curve analysis.

Result:

Out of 60 patients with stable COPD, 33 patients desaturated on exercise (n = 33/60). DS had significantly lower values of FEV₁ (P < 0.001), FVC (P < 0.01) FEV₁/FVC (P < 0.01) compared to NDS. EID had significant negative correlation with FEV₁ (r = 0.31, P < 0.01), resting oxygen saturation (r = 0.549, P < 0.001) and 6MWD (r = 0.511, P < 0.001). Resting SpO₂ ≤93% was found to a predictor of EID with a sensitivity and specificity of 83% and 78%, respectively.

Interpretation and Conclusion:

The 6MWT is a safe and sensitive test to recognize EID in normoxic stable COPD patients. Resting oxygen saturation is a good predictor of EID.

Effects of a Highly Portable Noninvasive Open Ventilation System on Activities of Daily Living in Patients with COPD

Background: For patients with chronic obstructive pulmonary disease (COPD), an increase in exercise tolerance and ability to perform activities of daily living (ADLs) can mean an improved quality of life with fewer exacerbations and lower health care expenses. We evaluated a wearable, noninvasive open ventilation (NIOV) system designed to enhance exercise capacity and increase mobility. Methods: Patients with stable, oxygen-dependent COPD were recruited for this prospective, open-label, crossover study. Inclusion criteria included supplemental oxygen use, elevated dyspnea score, and the ability to perform ADLs. Patients performed a selected ADL for as long as tolerable while using standard oxygen therapy. Following a rest period, the same ADL was repeated using the NIOV system. ADL endurance time, oxyhemoglobin saturation measured by pulse oximeter ( SpO₂), dyspnea, fatigue, and discomfort scores were recorded. Results: Thirty patients were enrolled and 29 patients completed the study. Mean ADL endurance increased by 85% (13.4 vs. 7.2 min) using NIOV compared with oxygen therapy (p<0.0001). Mean SpO₂ was significantly higher during ADLs using NIOV versus oxygen therapy (p<0.0001). Median dyspnea, fatigue, and discomfort scores were significantly lower using NIOV during ADLs compared to oxygen therapy (p<0.01). No device-related adverse events were observed. Conclusions: This study demonstrated that a novel, portable noninvasive open ventilation system can improve ADL performance in the home setting. Compared to standard oxygen therapy, the NIOV system provided statistically and clinically significant increases in ADL endurance time and oxygenation, while decreasing dyspnea, fatigue, and discomfort. The NIOV system appears to offer a practical option for increasing activity and exercise tolerance in oxygen-dependent patients with COPD.

Exertional hypoxemia in stable COPD is common and predicted by circulating proadrenomedullin

BACKGROUND

The prevalence of exertional hypoxemia in unselected patients with COPD is unknown. Intermittent hypoxia leads to adrenomedullin (ADM) upregulation through the hypoxia-inducible factor-1 pathway. We aimed to assess the prevalence and the annual probability to develop exertional hypoxemia in stable COPD. We also hypothesized that increased ADM might be associated with exertional hypoxemia and envisioned that adding ADM to clinical variables might improve its prediction in COPD.

METHODS

A total of 1,233 6-min walk tests and circulating proadrenomedullin (proADM) levels from 574 patients with clinically stable, moderate to very severe COPD enrolled in a multinational cohort study and followed up for 2 years were concomitantly analyzed.

RESULTS

The prevalence of exertional hypoxemia was 29.1%. In a matrix derived from a fitted-multistate model, the annual probability to develop exertional hypoxemia was 21.6%. Exertional hypoxemia was associated with greater deterioration of specific domains of health-related quality of life, higher severe exacerbation, and death annual rates. In the logistic linear and conditional Cox regression multivariable analyses, both FEV1% predicted and proADM proved independent predictors of exertional hypoxemia (P < .001 for both). Adjustment for comorbidities, including cardiovascular disorders, and exacerbation rate did not influence results. Relative to using FEV1% predicted alone, adding proADM resulted in a significant improvement of the predictive properties (P = .018). Based on the suggested nonlinear nomogram, patients with moderate COPD (FEV1% predicted = 50%) but high proADM levels (> 2 nmol/L) presented increased risk (> 30%) for exertional desaturation.

CONCLUSIONS

Exertional desaturation is common and associated with poorer clinical outcomes in COPD. ADM improves prediction of exertional desaturation as compared with the use of FEV1% predicted alone.

TRIAL REGISTRY

ISRCTN Register; No.: ISRCTN99586989; URL: www.controlled-trials.com.

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.

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.

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.

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.

Clinical and radiographic correlates of hypoxemia and oxygen therapy in the COPDGene study

BACKGROUND

Severe hypoxemia is a major complication of chronic obstructive pulmonary disease (COPD). Long-term oxygen therapy is beneficial in hypoxemic COPD patients. However, the clinical and radiographic predictors of hypoxemia and the use of oxygen therapy are not well described. This study aimed to find the correlates of resting hypoxemia and the pattern of oxygen use in moderate to severe COPD patients.

METHODS

Subjects with GOLD stage II or higher COPD from the first 2500 COPDGene subjects were included in this analysis. All subjects were current or ex-smokers between ages 45 and 80. Severe resting hypoxemia was defined as room air oxygen saturation (SpO(2)) ≤88%. Use of supplemental oxygen therapy was determined by questionnaire.

RESULTS

Eighty-two of 1060 COPD subjects (7.7%) had severe resting hypoxemia. Twenty-one of the 82 (25.6%) were not using continuous supplemental oxygen. Female sex, higher BMI, lower FEV(1), and enrollment in Denver were independent risk factors for hypoxemia; emphysema severity on quantitative chest CT scan did not predict hypoxemia. 132 of 971(13.6%) subjects without severe resting hypoxemia were using continuous supplemental oxygen. In non-hypoxemic oxygen users, Denver recruitment, higher BMI, lower FEV(1), and more severe dyspnea were associated with the use of continuous oxygen.

CONCLUSIONS

A large number of COPD patients without severe hypoxemia were using supplemental oxygen therapy and the pattern of oxygen use was affected by factors other than resting SpO(2) and emphysema severity. Longitudinal data will be required to reveal the effects of oxygen therapy in this subgroup.

CLINICAL TRIAL REGISTRATION

http://clinicaltrials.gov (NCT00608764).

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.

Exertional desaturation in patients with chronic obstructive pulmonary disease

Although the Centers for Medicare and Medicaid Services oxygen prescription guidelines utilize a threshold arterial oxygen tension <or=55 mmHg or an oxygen saturation <or=88%, a range of oxygen levels and relative declines have been used in investigations of exertional desaturation in patients with chronic obstructive pulmonary disease (COPD). There is no uniform definition of exertional hypoxemia or standardized exercise protocol to elicit decreases in oxygen levels in individuals with COPD. The causes for exertional desaturation in patients with COPD are multifactorial with ventilation-perfusion mismatching, diffusion-type limitation, shunting and reduced oxygen content of mixed venous blood all contributing to some degree. Neither resting oxygen saturation nor pulmonary function studies can reliably predict which patients with COPD will develop exertional desaturation. However, preserved pulmonary function, especially diffusing capacity, reliably predicts which patients with COPD will sustain oxygenation during exercise. Although exertional desaturation in patients with COPD appears to portend a poor prognosis, there is no evidence that maintenance of normoxemia during exercise improves the survival of these patients. Studies of the effect of supplemental oxygen on exercise performance in individuals with COPD who desaturate with exertion have yielded conflicting results. The use of short-term or "burst" oxygen either prior to or after exertion may not have significant clinical benefit. Differences in the definition of desaturation, mode of exercise, and characteristics of the patient population make it difficult to compare studies of exertional desaturation and its treatment and to determine their applicability to clinical practice.

Minimally Clinically Important Difference for the UCSD Shortness of Breath Questionnaire, Borg Scale, and Visual Analog Scale

Dyspnea is a primary symptom of chronic lung disease and an important outcome measure for clinical trials. Several standardized measures have been developed to evaluate this important symptom and are being used increasingly in clinical trials. The minimally clinically important difference (MCID) is not well defined for these measures but is important in interpreting the clinical meaning of results of studies in this area. The purpose of this paper is to evaluate the MCID for three commonly used measures to assess dyspnea in chronic lung disease: UCSD Shortness of Breath Questionnaire (SOBQ), Borg Scale (Borg), and Visual Analog Scale (VAS). The analysis is based on a retrospective review of published trials evaluating the response to a pulmonary rehabilitation or exercise intervention that is known to produce modest, but clinically meaningful changes for such patients. Using a distribution-based approach based primarily on effect size, the recommended MCID for these measures are: 5-units for the SOBQ, 1-unit for the Borg scale, and approximately 10 to 20 units for the VAS.

Oxygen for relief of dyspnea: what is the evidence?

PURPOSE OF REVIEW

Refractory dyspnea is a common and distressing symptom complicating respiratory illness, including chronic obstructive pulmonary disease, and life-limiting illnesses in general, including cancer. Oxygen is often prescribed for relief of dyspnea and several consensus guidelines support this practice. The goal of this review is to outline the evidence for the use of oxygen for relief of dyspnea, with specific attention to situations in which oxygen is not already funded through long-term oxygen treatment guidelines (i.e., when PaO2 is >/=55 mmHg; also known as palliative oxygen).

RECENT FINDINGS

Several recent systematic reviews, two focusing on people with chronic obstructive pulmonary disease and the other focusing on people with cancer, strengthen the evidence base behind the use of palliative oxygen for relief of refractory dyspnea, and support the observation that there are subgroups of people who benefit from oxygen, such as individuals with chronic obstructive pulmonary disease.

SUMMARY

The data highlighted in this review support the belief that certain individuals benefit from the use of palliative oxygen but continue to suggest that definitive randomized trials are required to fully establish the benefit of palliative oxygen and to delineate characteristics predictive of benefit.

Oxygen therapy during exercise training in chronic obstructive pulmonary disease

BACKGROUND

Exercise training within the context of pulmonary rehabilitation improves outcomes of exercise capacity, dyspnea and health-related quality of life in individuals with chronic obstructive pulmonary disease (COPD). Supplemental oxygen in comparison to placebo increases exercise capacity in patients performing single-assessment exercise tests. The addition of supplemental oxygen during exercise training may enable individuals with COPD to tolerate higher levels of activity with less exertional symptoms, ultimately improving quality of life.

OBJECTIVES

To determine how supplemental oxygen in comparison to control (compressed air or room air) during the exercise-training component of a pulmonary rehabilitation program affects exercise capacity, dyspnea and health-related quality of life in individuals with COPD.

SEARCH STRATEGY

All records in the Cochrane Airways Group Specialized Register of trials coded as 'COPD' were searched using the following terms: (oxygen* or O2*) AND (exercis* or train* or rehabilitat* or fitness* or physical* or activ* or endur* or exert* or walk* or cycle*). Searching the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE, EMBASE and CINAHL databases identified studies. The last search was carried out in June 2006.

SELECTION CRITERIA

Only randomized controlled trials (RCTs) comparing oxygen-supplemented exercise training to non-supplemented exercise training (control group) were considered for inclusion. Participants were 18 years or older, diagnosed with COPD and did not meet criteria for long-term oxygen therapy. No studies with mixed populations (pulmonary fibrosis, cystic fibrosis, etc) were included. Exercise training was greater than or equal to three weeks in duration and included a minimum of two sessions a week.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion in the review and extracted data. Weighted mean differences (WMD) with 95% confidence intervals (CI) were calculated using a random-effects model. Missing data were requested from authors of primary studies.

MAIN RESULTS

Five RCTs met the inclusion criteria. The maximum number of studies compared in the meta-analysis was three (31 on oxygen versus 32 control participants), because all included studies did not measure the same outcomes. When two studies were pooled, statistically significant improvements of oxygen-supplemented exercise training were found in constant power exercise time, WMD 2.68 minutes (95% CI 0.07 to 5.28 minutes). Supplemental oxygen increased the average exercise time from 6 to 14 minutes; the control intervention increased average exercise time from 6 to 12 minutes. Constant power exercise end-of-test Borg score (on a scale from 1 to 10) also showed statistically significant improvements with oxygen-supplemented exercise training, WMD -1.22 units (95% CI -2.39 to -0.06). One study showed a significant improvement in the change of Borg score after the shuttle walk test, by -1.46 units (95% CI -2.72 to -0.19). There were no significant differences in maximal exercise outcomes, functional exercise outcomes (six-minute walk test), shuttle walk distance, health-related quality of life or oxygenation status. According to the GRADE system most outcomes were rated as low quality because they were limited by study quality.

AUTHORS' CONCLUSIONS

This review provides little support for oxygen supplementation during exercise training for individuals with COPD, but the evidence is very limited. Studies with larger number of participants and strong design are required to permit strong conclusions, especially for functional outcomes such as symptom alleviation, health-related quality of life and ambulation.

Comparison of six-minute walking tests conducted with and without supplemental oxygen in patients with chronic obstructive pulmonary disease and exercise-induced oxygen desaturation

BACKGROUND

There are contradictory reports in the literature on the effects of supplemental oxygen administered before or after exercise tests. In light of this, we compared the results of 6-minute walking tests performed in room-air conditions (A6MWT) and with supplemental oxygen (O6MWT) in patients with chronic obstructive pulmonary disease (COPD) and exercise-induced oxygen desaturation.

PATIENTS AND METHODS

Thirty-one patients with COPD were included in the study. The A6MWT and O6MWT were performed in randomized order on each patient. During the tests, severity of dyspnea and tiring of the leg were evaluated by the Modified Borg Scale. Heart rate and pulsed oxygen saturation and blood pressure were measured by pulse oximeter.

RESULTS

Walking distance was longer with the O6MWT than with the A6MWT (P=0.001). The O6MWT resulted in a smaller increase in dyspnea, leg fatigue, and heart rate and a smaller drop in pulsed saturation than the A6MWT (P<0.05). The walking distance with the O6MWT correlated with respiratory function and hemodynamic parameters (P<0.05).

CONCLUSION

The O6MWT, which produced less hemodynamic stress and was safer than the A6MWT, might provide more accurate information on exercise limitation for patients with COPD. These results suggest that the O6MWT can be used as a standard walking exercise test for patients with COPD and exercise-induced oxygen desaturation.

Short burst oxygen therapy after activities of daily living in the home in chronic obstructive pulmonary disease

BACKGROUND

Short burst oxygen therapy (SBOT) is widely prescribed in the UK with little evidence of benefit. A study was performed to examine whether SBOT benefits patients when undertaking normal activities at home among those who already use it.

METHODS

Twenty-two patients with chronic obstructive pulmonary disease (COPD) were included in the study. All regularly used SBOT at home and claimed that it helps them. Each patient chose two daily living activities for which they used SBOT for relief of breathlessness. Patients were then randomised to use either an air or oxygen gas cylinder. At least 15 min later the same activity was performed using the other gas cylinder. The same process was then repeated for the second chosen activity. The main endpoints were subjective and objective times to recovery, analysed for each activity separately or taking the average over the two activities. A paired statistical analysis was performed.

RESULTS

All patients used SBOT with nasal prongs after exercise. Using the average recovery time over two activities for each patient, the mean objective recovery time was 38 s lower (95% CI -81 to +5) using oxygen and the mean subjective recovery time was 34 s lower (95% CI -69 to +2). Five patients were correctly able to distinguish oxygen from air after both activities and there was a suggestion that their recovery times were shorter than those who did not correctly identify the gases (91 s vs 20 s using objective recovery times, and 80 s vs 22 s using subjective recovery times), although this was a subgroup analysis based on only five patients with non-significant results.

CONCLUSIONS

There is some evidence that SBOT shortens recovery time after activities of daily living in a selected group of patients with COPD, but the effect is small. There appears to be a subgroup of patients who may benefit to a much greater degree.

Palliative management of refractory dyspnea in COPD

COPD is a progressive illness with worldwide impact. Patients invariably reach a point at which they require palliative interventions. Dyspnea is the most distressing symptom experienced by these patients; when not relieved by traditional COPD management strategies it is termed "refractory dyspnea" and palliative approaches are required. The focus of care shifts from prolonging survival to reducing symptoms, increasing function, and improving quality of life. Numerous pharmacological and non-pharmacological interventions can achieve these goals, though evidence supporting their use is variable. This review provides a summary of the options for the management of refractory dyspnea in COPD, outlining currently available evidence and highlighting areas for further investigation. Topics include oxygen, opioids, psychotropic drugs, inhaled furosemide, Heliox, rehabilitation, nutrition, psychosocial support, breathing techniques, and breathlessness clinics.

Short-term ambulatory oxygen for chronic obstructive pulmonary disease

BACKGROUND

Ambulatory oxygen is defined as the use of supplemental oxygen during exercise and activities of daily living. Ambulatory oxygen therapy is often used for patients on long term oxygen therapy during exercise, or for non long term oxygen therapy users who achieve some subjective and/or objective benefit from oxygen during exercise. The evidence for the use of ambulatory oxygen therapy is extrapolated from two sources: longer term studies and single assessment studies. Longer term studies assess the impact of ambulatory oxygen therapy used at home during activities of daily living. Single assessment studies compare performance during an exercise test using oxygen with performance during an exercise test using placebo air.

OBJECTIVES

To determine the efficacy of ambulatory oxygen in patients with COPD using single assessment studies.

SEARCH STRATEGY

The Cochrane Airways Group COPD register was searched with predefined search terms. Searches were current as of March 2005.

SELECTION CRITERIA

Only randomised controlled trials were included. Studies did not have to be blinded. Studies had to compare oxygen and placebo when administered to people with COPD who were undergoing an exercise test.

DATA COLLECTION AND ANALYSIS

Two reviewers (JB, B'ON) extracted and entered data in to RevMan 4.2.

MAIN RESULTS

Thirty one studies (contributing 33 data sets), randomising 534 participants met the inclusion criteria of the review. Oxygen improved all pooled outcomes relating to endurance exercise capacity (distance, time, number of steps) and maximal exercise capacity (exercise time and work rate). Data relating to VO2 max could not be pooled and results from the original studies were not consistent. For the secondary outcomes of breathlessness, SaO2 and VE, comparisons were made at isotime. In all studies except two the isotime is defined as the time at which the placebo test ended. Oxygen improved breathlessness, SaO2/PaO2 and VE at isotime with endurance exercise testing. There was no data on breathlessness at isotime with maximal exercise testing. Oxygen improved SaO2/PaO2 and reduced VE at Isotime.

AUTHORS' CONCLUSIONS

This review provides some evidence from small, single assessment studies that ambulatory oxygen improves exercise performance in people with moderate to severe COPD. The results of the review may be affected by publication bias, and the small sample sizes in the studies. Although positive, the findings of the review require replication in larger trials with more distinct subgroups of participants. Maximal or endurance tests can be used in ambulatory oxygen assessment. Consideration should be given to the measurement of SaO2 and breathlessness at isotime as these provide important additional information. We recommend that these outcomes are included in the assessment for ambulatory oxygen. Future research needs to establish the level of benefit of ambulatory oxygen in specific subgroups of people with COPD.

Short term ambulatory oxygen for chronic obstructive pulmonary disease

BACKGROUND

Ambulatory oxygen is defined as the use of supplemental oxygen during exercise and activities of daily living. Ambulatory oxygen therapy is often used for patients on long term oxygen therapy during exercise, or for non long term oxygen therapy users who achieve some subjective and/or objective benefit from oxygen during exercise. The evidence for the use of ambulatory oxygen therapy is extrapolated from two sources: longer term studies and single assessment studies. Longer term studies assess the impact of ambulatory oxygen therapy used at home during activities of daily living. Single assessment studies compare performance during an exercise test using oxygen with performance during an exercise test using placebo air.

OBJECTIVES

To determine the efficacy of ambulatory oxygen in patients with COPD using single assessment studies.

SEARCH STRATEGY

The Cochrane Airways Group COPD register was searched with predefined search terms. Searches were current as of March 2004.

SELECTION CRITERIA

Only randomised controlled trials were included. Studies did not have to be blinded. Studies had to compare oxygen and placebo when administered to people with COPD who were undergoing an exercise test.

DATA COLLECTION AND ANALYSIS

Two reviewers (JB, B'ON) extracted and entered data in to RevMan 4.2.7.

MAIN RESULTS

Twenty-seven studies (contributing 29 data sets), randomising 469 participants met the inclusion criteria of the review. Oxygen improved all pooled outcomes relating to endurance exercise capacity (distance, time, number of steps) and maximal exercise capacity (exercise time and work rate). Data relating to VO2max could not be pooled and results from the original studies were not consistent. For the secondary outcomes of breathlessness, SaO2 and VE, comparisons were made at isotime. In all studies except two the isotime is defined as the time at which the placebo test ended. Oxygen improved breathlessness, SaO2/PaO2 and VE at isotime with endurance exercise testing. There was no data on breathlessness at isotime with maximal exercise testing. Oxygen improved SaO2/PaO2 at isotime; the reduction in VE did not reach statistical significance.

AUTHORS' CONCLUSIONS

This review provides some evidence from small, single assessment studies that ambulatory oxygen improves exercise performance in people with moderate to severe COPD. The results of the review may be affected by publication bias, and the small sample sizes in the studies. Although positive, the findings of the review require replication in larger trials with more distinct subgroups of participants. Maximal or endurance tests can be used in ambulatory oxygen assessment, but endurance tests may be more appropriate as they are more related to activities of daily living. Consideration should be given to the measurement of SaO2 and breathlessness at isotime as these provide important additional information. We recommend that these outcomes are included in the assessment for ambulatory oxygen. Future research needs to establish the level of benefit of ambulatory oxygen in specific subgroups of people with COPD.

Severe chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) exacts a heavy toll on society, yet its prevention, diagnosis and treatment receives inadequate attention from both the medical community and from society at large. Guidelines released in 2001 from the Global Initiative for Chronic Obstructive Lung Disease (GOLD) are aimed at redressing this inequity. In this review, we integrate information from the GOLD guidelines with recent updates on the prevention, treatment and management as related specifically to the most severe form of this disease. In order to help distinguish COPD from other disorders that may mimic or confound its treatment, we place particular emphasis on the definition, underlying pathophysiology and diagnosis of COPD. In addition, we discuss future directions in pharmacotherapy.

The use of oxygen in the palliation of breathlessness. A report of the expert working group of the scientific committee of the association of palliative medicine

Dyspnoea is a common, distressing symptom and difficult to control with medical treatment. The role of oxygen in reducing the severity of the symptoms and improving quality of life is still unclear. A working party of the Association of Palliative Medicine Science Committee set out to examine the evidence concerning the use of oxygen for the palliation of breathlessness in COPD, advanced cancer and chronic heart failure and to make recommendations for clinicians working in palliative care. There were very few randomised controlled trials available for any of these conditions. There was no evidence available for heart failure, very little for advanced cancer and although there were a number of trials on the use of oxygen in COPD very few, until recently, used reduction of breathlessness as an outcome measure. Recommendations are made on the basis of the evidence available and expert opinion such as the Royal College of Physicians report on the use of domiciliary oxygen. Oxygen use has to be tailored to the individual and a formal assessment made of its efficacy for reducing breathlessness and improving quality of life for that person [corrected].