Oxygen supplementation before or after submaximal exercise in patients with chronic obstructive pulmonary disease

Home oxygen therapy: evidence versus reality

INTRODUCTION

LTOT is a well-established treatment option for hypoxemic patients. Scientific evidence for its benefits of LTOT dates back to the 1980s, when two randomized controlled trials showed prolonged survival in COPD-patients undergoing LTOT for at least 15 hours/day. In contrast, the potential benefits of LTOT in non-COPD-patients has not been well researched and the recommendations for its application are primarily extrapolated from trials on COPD-patients. Recently, a large trial confirmed that COPD-patients who don't meet classic indication criteria, and have moderate desaturation at rest or during exercise, do not benefit from oxygen therapy. Also the significant technical evolution of LTOT devices has improved its application. Areas covered: A literature research was performed in pubmed regarding home oxygen therapy (terms: LTOT, ambulatory oxygen therapy, short burst oxygen therapy, nocturnal oxygen therapy). Expert commentary: LTOT proved a survival benefit for COPD patients about 30 years ago. Whether the results of these trials are still valid for patients under modern treatment guidelines remains unknown. Nevertheless, the classic indication criteria for LTOT still persist in guidelines, since there is a lack of updated evidence for the effects of LTOT in more severe hypoxemic patients.

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.

Prescribing practice for intermittent oxygen therapy: a GP survey

Introduction:UK figures show that the prescription of home oxygen cylinders for intermittent use is substantial. Aim: To examine GP assessment criteria and prescribing practice for intermittent oxygen therapy in patients with a diagnosis of chronic obstructive pulmonary disease (COPD) in Northern Ireland. Methods:A postal questionnaire was sent to all GPs (n = 534) in two health boards who had prescribed cylinder oxygen in a six month period prior to the study. The questionnaire was piloted to establish reliability and validity. Results:Completed questionnaires were returned by 52% (280/534) of GPs. GPs ‘most frequently’ used advice from hospital specialists [82% (230/280)] to determine the need for intermittent oxygen. Criteria such as breathlessness score on exercise (e.g., BORG), oximetry on exercise, local guidelines or national guidelines were used less frequently or never. Conclusions:Most patients are likely to have been prescribed intermittent oxygen without any objective assessment. Implementation of evidence-based guidelines and a formal oxygen assessment service, would rationalize the use of intermittent oxygen therapy and enable better targeting of this expensive resource.

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.

When should I be considering home oxygen for my patients?

The ability to provide oxygen in a patient’s home can offer enormous benefits, including improvements in life expectancy when given in the appropriate setting. Confusingly, however, home oxygen is available in many forms, including long-term oxygen therapy (LTOT), ambulatory oxygen therapy (AOT), palliative oxygen therapy (POT) and short-burst oxygen therapy (SBOT)—each with varying degrees of supporting evidence. The British Thoracic Society (BTS) has recently published new guidance on home oxygen therapy, after collating the available evidence. This article aims to summarise those guidelines, focusing on who should and should not be considered for oxygen therapy. Although the BTS guidelines target a UK audience, many of the principles covered below are applicable internationally, even if the availability of certain oxygen modalities and supporting service arrangements may vary between different healthcare systems.

Long-term oxygen therapy

Long-term oxygen therapy (LTOT) has been shown to reduce pulmonary hypertension and improve survival in patients with chronic obstructive pulmonary disease and resting hypoxemia (reduced arterial partial pressure of oxygen ≤55 mmHg). However, the benefit of its use for chronic pulmonary diseases other than chronic obstructive pulmonary disease as well as for nonpulmonary conditions is debatable. Its role in patients with mild hypoxemia (reduced arterial partial pressure of oxygen >55 mmHg at rest) is presently being investigated in the LOTT. A meta-analysis of four controlled trials reporting the role of LTOT in patients with either nocturnal desaturation or daytime moderate hypoxemia found no difference in survival between patients on LTOT than those without. Advances in oxygen delivery and conservation devices have made domiciliary oxygen therapy more practical and popular for patients. There still remain concerns with the actual compliance of therapy among the needy patients.

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.

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.

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.

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 and helium gas mixtures for dyspnoea

PURPOSE OF REVIEW

Recent reports of the benefits of helium/oxygen gas mixtures (heliox) use for the relief of dyspnoea and exercise limitation have stimulated interest in the use of heliox in the palliation of dyspnoea especially in chronic obstructive pulmonary disease patients. With better understanding of the mechanistic causes of dyspnoea in these patients theoretical benefits of heliox have been suggested. This report considers the evidence to support this role and reviews the current position on heliox administration and use as a carrier gas for nebulization therapies.

RECENT FINDINGS

Heliox can effectively improve exercise limitations, decrease the work of breathing and reduce dyspnoea in lung cancer and chronic obstructive pulmonary disease patients; in the latter it works by reducing dynamic hyperinflation. The evidence comes from short-term assessments of single exercise tests and additional benefits are seen when used in conjunction with other current therapies such as supplemental oxygen and nebulization. Dedicated devices with better comprehensive guidelines for administration have been developed to alleviate some of the reluctance of use.

SUMMARY

Heliox use could prove beneficial either administered alone or as an addition to current therapies for the palliation of dyspnoea and give significant improvement in outcomes of rehabilitation programmes. There is still an urgent need to identify which patients are the best candidates for heliox use and translate the significant short-term benefits into long-term improvements in functioning and quality of life.

End of life care in chronic obstructive pulmonary disease: in search of a good death

Chronic obstructive pulmonary disease (COPD) is an incurable, progressive illness that is the fourth commonest cause of death worldwide. Death tends to occur after a prolonged functional decline associated with uncontrolled symptoms, emotional distress and social isolation. There is increasing evidence that the end of life needs of those with advanced COPD are not being met by existing services. Many barriers hinder the provision of good end of life care in COPD, including the inherent difficulties in determining prognosis. This review provides an evidence-based approach to overcoming these barriers, summarising current evidence and highlighting areas for future research. Topics include end of life needs, symptom control, advance care planning, and service development to improve the quality of end of life care.

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.

Short-burst oxygen therapy in chronic obstructive pulmonary disease

INTRODUCTION

Despite widespread prescription, the efficacy of short-burst oxygen therapy has not been established.

AIM

To systematically review the available evidence for short-burst oxygen therapy in patients with chronic obstructive pulmonary disease (COPD).

METHOD

Retrieval of randomized-controlled trials comparing short-burst oxygen (oxygen for breathlessness at rest, before exercise and after exercise) with placebo in patients with COPD. Data were extracted and, where possible, outcome measures were combined using RevMan analyses 4.2. The methodological quality of each trial was assessed using the PEDro scale.

RESULTS

Studies differed in the type of exercise test used, the amount of oxygen delivered and in the length of time for pre- or post-dosing. Quality of the included studies as rated by the PEDro scale was good. For many outcome measures, data could not be pooled for meta-analysis. Short-burst oxygen is primarily indicated for the symptomatic relief of breathlessness, and the bulk of evidence from this review suggests that short-burst oxygen therapy does not reduce breathlessness. For secondary outcome measures (exercise capacity, oxygen saturation [SaO(2)], other ventilatory parameters), the results are not consistent.

CONCLUSION

The studies in this review suggest that the widespread prescription of short-burst oxygen is not evidence-based. If prescription is to continue, the scientific rationale for short-burst oxygen therapy must be established.

The Effect of Helium and Oxygen on Exercise Performance in Chronic Obstructive Pulmonary Disease

RATIONALE

Breathing supplemental oxygen reduces breathlessness during exercise in patients with chronic obstructive pulmonary disease (COPD). Replacing nitrogen with helium reduces expiratory flow resistance and may improve lung emptying. Combining these treatments should be independently effective.

OBJECTIVES

Study the effect of changing oxygen or helium concentration in inspired gas during exercise in patients with stable COPD.

METHODS

In 82 patients (mean age, 69.7 yr; mean FEV(1), 42.6% predicted), we measured endurance shuttle walking distance, resting and exercise oxygen saturation, and end-exercise dyspnea (Borg scale) while patients breathed Heliox28 (72% He/28% O(2)), Heliox21 (79% He/21% O(2)), Oxygen28 (72% N(2)/28% O(2)), or medical air (79% N(2)/21% O(2)). Gases were administered using a randomized, blinded, crossover design via a face mask and an inspiratory demand valve.

RESULTS

Breathing Heliox28 increased walking distance (mean+/-SD, 147+/-150 m) and reduced Borg score (-1.28+/-1.30) more than any other gas mixture. Heliox21 significantly increased walking distance (99+/-101 m) and reduced dyspnea (Borg score, -0.76+/-0.77) compared with medical air. These changes were similar to those breathing Oxygen28. The effects of helium and oxygen in Heliox28 were independent. The increase in walking distance while breathing Heliox28 was inversely related to baseline FEV(1) breathing air.

CONCLUSION

Reducing inspired gas density can improve exercise performance in COPD as much as increasing inspired oxygen. These effects can be combined as Heliox28 and are most evident in patients with more severe airflow obstruction.

Putting policy into practice: the example of COPD

Chronic lung disease is one of the commonest reasons for consulting a health professional, and there may be as many as 3 million people in the UK with undiagnosed chronic obstructive pulmonary disease (COPD). This fourth article in a series on long-term conditions examines the policy developments that have been put in place to manage the burden of chronic disease in England and Wales, and argues that more remains to be done if COPD is to be properly addressed.

Short burst oxygen therapy in chronic obstructive pulmonary disease: a patient survey and cost analysis

The prescription of home oxygen cylinders is substantial. This study aimed to establish patient's current use of short burst oxygen therapy in chronic obstructive pulmonary disease (COPD) and to examine potential cost savings if cylinder use had been replaced by a concentrator. An interviewer-administered questionnaire was completed by 100 patients currently receiving short burst oxygen therapy. Patients reported that they used their oxygen before exercise/activity (26%), during exercise (19%), after exercise/activity (87%) and at rest (46%) and mostly for the relief of symptomatic breathlessness. The length of time [mean (SD)] patients had oxygen at home was 27.42 (29.31) months. Of those patients using cylinders, savings could have been made by transferring from cylinders to concentrators. While withdrawal of oxygen may be difficult, an oxygen assessment service could ensure that future prescription is aimed at those who benefit and is delivered by the most cost-effective method.

Management of severe COPD

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide, and the burden of the disorder will continue to increase over the next 20 years despite medical intervention. Apart from smoking cessation, no approach or agent affects the rate of decline in lung function and progression of the disease. Especially in the later phase, COPD is a multicomponent disorder, and various integrated intervention strategies are needed as part of the optimum management programme. This seminar describes largely non-pharmacological interventions aimed at improving health status and function of disabled patients. Exacerbations become progressively more troublesome as baseline lung function declines, commonly necessitating hospital admission and associated with the development of acute respiratory failure.

Effect of oxygen on recovery from maximal exercise in patients with chronic obstructive pulmonary disease

BACKGROUND

The effects of oxygen on recovery from exercise in patients with chronic obstructive pulmonary disease (COPD) are not clearly known. A study was undertaken to determine whether oxygen given after maximal exercise reduced the degree of dynamic hyperinflation and so reduced the perception of breathlessness.

METHODS

Eighteen patients with moderate to severe COPD performed maximal symptom limited exercise on a cycle ergometer. During recovery they received either air or oxygen at identical flow rates in a randomised, single blind, crossover design. Inspiratory capacity, breathing pattern data, dyspnoea intensity, and leg fatigue scores were collected at regular intervals during recovery. At a subsequent visit patients underwent a similar protocol but with a face mask in situ to eliminate the effects of instrumentation.

RESULTS

When oxygen was given the time taken for resolution of dynamic hyperinflation was significantly shorter (mean difference between air and oxygen 6.61(1.65) minutes (95% CI 3.13 to 10.09), p = 0.001). Oxygen did not, however, reduce the perception of breathlessness during recovery nor did it affect the time taken to return to baseline dyspnoea scores in either the instrumented or non-instrumented state (mean difference 2.11 (1.41) minutes (95% CI -0.88 to 5.10), p = 0.15).

CONCLUSIONS

Oxygen reduces the degree of dynamic hyperinflation during recovery from exercise but does not make patients feel less breathless than breathing air. This suggests that factors other than lung mechanics may be important during recovery from exercise, or it may reflect the cooling effect of both air and oxygen.