***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Supplemental oxygen in patients with chronic obstructive pulmonary disease ( COPD ) and exercise hypoxaemia improves exercise capacity and dyspnoea . However , the benefit of oxygen during pulmonary rehabilitation in these patients is still unknown . METHODS Twenty five patients with stable COPD ( mean ( SD ) forced expiratory volume in one second ( FEV1 ) 0.76 ( 0.29 ) l and 30.0 (9.89)% predicted , arterial oxygen tension ( Pao 2 ) 8.46 ( 1.22 ) kPa , arterial carbon dioxide tension ( Paco 2 ) 6.32 ( 1.01 ) kPa ) and significant arterial desaturation on exercise ( 82.0 (10.4)% ) were entered onto a pulmonary rehabilitation programme . Patients were r and omised to train whilst breathing oxygen ( OT ) ( n = 13 ) or air ( AT ) ( n = 12 ) , both at 4 l/min . Assessment s included exercise tolerance and associated dyspnoea using the shuttle walk test ( SWT ) and Borg dyspnoea score , health status , mood state , and performance during daily activities . RESULTS The OT group showed a significant reduction in dyspnoea after rehabilitation compared with the AT group ( Borg mean difference –1.46 ( 95 % CI –2.72 to –0.19 ) ) but there were no differences in other outcome measures : SWT difference –23.6 m ( 95 % CI –70.7 to 23.5 ) , Chronic Respiratory Disease Question naire 3.67 ( 95 % CI –7.70 to 15.1 ) , Hospital Anxiety and Depression Scale 1.73 ( 95 % CI –2.32 to 5.78 ) , and London Chest Activity of Daily Living Scale –2.18 ( 95 % CI –7.15 to 2.79 ) . At baseline oxygen significantly improved SWT ( mean difference 27.3 m ( 95 % CI 14.7 to 39.8 ) and dyspnoea ( –0.68 ( 95 % CI –1.05 to –0.31 ) ) compared with placebo air . CONCLUSIONS This study suggests that supplemental oxygen during training does little to enhance exercise tolerance although there is a small benefit in terms of dyspnoea . Patients with severe disabling dyspnoea may find symptomatic relief with supplemental oxygen Background Patients with chronic obstructive pulmonary disease ( COPD ) who are not severely hypoxaemic at rest may experience significant breathlessness on exertion , and ambulatory oxygen is often prescribed in this circumstance despite a lack of conclusive evidence for benefit . This study aim ed to determine whether such patients benefit from domiciliary ambulatory oxygen and , if so , which factors may be associated with benefit . Methods This was a 12 week , parallel , double-blinded , r and omised , placebo-controlled trial of cylinder air versus cylinder oxygen , provided at 6 l/min intranasally , for use during any activity provoking breathlessness . Patients underwent baseline measurements of arterial blood gases and lung function . Outcome measures assessed dyspnoea , health-related quality of life , mood disturbance , functional status and cylinder utilisation . Data were analysed on an intention-to-treat basis , p≤0.05 . Results 143 subjects ( 44 female ) , mean±SD age 71.8±9.8 years , forced expiratory volume in 1 s (FEV1)1.16±0.51 lites , Pao2 9.5±1.1 kPa ( 71.4±8.5 mm Hg ) were r and omised , including 50 patients with exertional desaturation to ≤88 % . No significant differences in any outcome were found between groups receiving air or oxygen . Statistically significant but clinical ly small improvements in dyspnoea and depression were observed in the whole study group over the 12 weeks of the study . Conclusion In breathless patients with COPD who do not have severe resting hypoxaemia , domiciliary ambulatory oxygen confers no benefits in terms of dyspnoea , quality of life or function . Exertional desaturation is not predictive of outcome . Intranasal gas ( either air or oxygen ) may provide a placebo benefit . Clinical trial number ACTRN12605000457640 Long-term oxygen therapy may limit a patient 's ability to remain active and may be detrimental to the rehabilitation process . This study aim ed to determine the effect of ambulatory oxygen on quality of life and exercise capacity in patients with chronic obstructive pulmonary disease fulfilling the usual criteria of long-term oxygen therapy . In a 1-yr , r and omised , three-period , crossover trial , 24 patients ( mean age 68 yrs ; mean arterial partial pressure of oxygen at rest 7.1 kPa ( 53 mmHg ) ) were allocated to one of the six possible sequences generated by three interventions : 1 ) st and ard therapy ( home oxygen therapy with an oxygen concentrator only ) ; 2 ) st and ard therapy plus as-needed ambulatory oxygen ; and 3 ) st and ard therapy plus ambulatory compressed air . The comparison of ambulatory oxygen versus ambulatory compressed air was double blind . The main outcomes were quality of life ( Chronic Respiratory Question naire ) , exercise tolerance ( 6-min walk test ) and daily duration of exposure to oxygen therapy . The trial was stopped prematurely after an interim analysis . On average , the patients used few ambulatory cylinders ( 7.5 oxygen cylinders versus 7.4 compressed air cylinders over a 3-month study period ) . Ambulatory oxygen had no effect on any of the outcomes . In conclusion , the current results do not support the widespread provision of ambulatory oxygen to patients with oxygen-dependent chronic obstructive pulmonary disease The aim of this study was to determine whether long-term oxygen therapy ( LTOT ) reduces hospitalisation in hypoxaemic patients with chronic obstructive pulmonary disease ( COPD ) . The circumstances of initiation of LTOT ( start during hospitalisation versus start as an outpatient ) and compliance with oxygen were also investigated ( continuous oxygen therapy ( COT ) ≥15 h daily versus noncontinuous oxygen therapy ( NCOT ) < 15 h daily ) . A total 246 COPD patients were studied , with each patient acting as their own control . Patients were divided into four groups : 125 patients on COT who started LTOT in conjunction with hospitalisation  , 37 patients on COT who started LTOT as out patients  , 58 patients on NCOT who started LTOT in conjunction with hospitalisation  and 26 patients on NCOT who started LTOT as  out patients . Admission rates , days spent in hospital and number of patients with at least one hospitalisation ( ever hospitalised ) were compared in two periods of 10 months before and after initiation of LTOT . Overall during the LTOT period , in comparison with the preoxygen period , the admission rates , hospital days and “ ever hospitalised ” were reduced by 23.8 % , 43.5 % and 31.2 % , respectively . Among patients who started LTOT as out patients , a tendency towards a higher effect in the compliant group was observed . This study shows that in hypoxaemic chronic obstructive pulmonary disease patients  , long-term oxygen therapy is associated with a reduction in hospitalisation BACKGROUND : To date only two controlled studies have been published on the effects of domiciliary oxygen treatment on survival in patients with chronic obstructive pulmonary disease ( COPD ) with advanced respiratory failure . The survival in such patients despite oxygen treatment remains poor . The prescription of long term oxygen therapy ( LTOT ) in less severe disease remains controversial . The aim of this study was to evaluate the rationale for prescribing oxygen to patients with COPD with moderate hypoxaemia . METHODS : One hundred and thirty five patients with COPD , with PaO2 7.4 - 8.7 kPa ( 56 - 65 mmHg ) and advanced airflow limitation ( mean ( SD ) forced expiratory volume in one second ( FEV1 ) 0.83 ( 0.28 ) 1 ) , were r and omly allocated to a control ( n = 67 ) and LTOT ( n = 68 ) group . The patients were followed every three months for at least three years or until death . RESULTS : The cumulative survival rate was 88 % at one year , 77 % at two years , and 66 % at three years . No significant differences were found in survival rates between patients treated with LTOT and controls , nor did longer oxygen use ( over 15 hours per day ) improve survival . Younger age , better spirometric values , and higher body mass index predicted better survival . CONCLUSIONS : Domiciliary oxygen treatment does not prolong survival in patients with COPD with moderate hypoxaemia . Airway limitation seems to determine survival in this group of patients It is unknown whether acute response to ambulatory oxygen ( O2 ) predicts longer term improvement in health-related quality of life ( HRQL ) in chronic obstructive pulmonary disease ( COPD ) patients . The aims of this study were 1 ) to assess the short-term clinical impact , as determined by HRQL , of ambulatory O2 in a 12-week , double-blind , r and omised crossover study of O2 ( versus cylinder compressed air ) of dyspnoeic but not chronically hypoxic COPD patients with exertional desaturation ≤88 % ( n=41 ) , and 2 ) to determine whether either baseline characteristics or acute response to O2 predicts short-term ( 12 weeks ) response . Primary outcome measures were Chronic Respiratory Question naire ( CRQ ) , Hospital Anxiety and Depression scale and the short form (SF)-36 . Improvements were seen in all domains of the CRQ for cylinder O2 compared with cylinder air . Significant improvements were also noted in anxiety and depression and in certain domains of the SF-36 . There were 28 ( 68 % ) acute responders to cylinder O2 ( defined as increase in 6‐min walk ≥54 m or decrease in post-Borg dyspnoea ≥1 ) and 23 ( 56 % ) short-term responders ( defined as clinical ly significant improvement in CRQ ) . However , acute and short-term responses were not correlated with no predictors of short-term response identified . At study completion , 14 ( 41 % ) of acute or short-term responders did not want to continue therapy , with 11 citing poor acceptability or tolerability . Short-term ambulatory oxygen is associated with significant improvements in health-related quality of life . These benefits can not be predicted by baseline characteristics or acute response . Despite acute or short-term response , a substantial proportion of patients declined ambulatory oxygen Abstract Lightweight ambulatory oxygen devices are provided on the assumptions that they enhance compliance and increase activity , but data to support these assumptions are lacking . We studied 22 patients with severe chronic obstructive pulmonary disease receiving long-term oxygen therapy ( 14 men , average age = 66.9 y , FEV1 = 33.6%pred , PaO2 at rest = 51.7 torr ) who were using E-cylinders as their portable oxygen . Subjects were recruited at 5 sites and studied over a 2-week baseline period and for 6 months after r and omizing them to either continuing to use 22-lb E-cylinders towed on a cart or to carrying 3.6-lb aluminum cylinders . Utilizing novel electronic devices , ambulatory and stationary oxygen use was monitored continuously over the 2 weeks prior to and the 6 months following r and omization . Subjects wore tri-axial accelerometers to monitor physical activity during waking hours for 2–3 weeks prior to , and at 3 and 6 months after , r and omization . Seventeen subjects completed the study . At baseline , subjects used 17.2 hours of stationary and 2.5 hours of ambulatory oxygen daily . At 6 months , ambulatory oxygen use was 1.4 ± 1.0 hrs in those r and omized to E-cylinders and 1.9 ± 2.4 hrs in those using lightweight oxygen ( P = NS ) . Activity monitoring revealed low activity levels prior to r and omization and no significant increase over time in either group . In this group of severe chronic obstructive pulmonary disease patients , providing lightweight ambulatory oxygen did not increase either oxygen use or activity . Future efforts might focus on strategies to encourage oxygen use and enhance activity in this patient group . This trial is registered at Clinical Trials.gov ( NCT003257540 ) RATIONALE Ambulatory oxygen improves acute exercise performance in people with chronic obstructive pulmonary disease ( COPD ) . This improvement may not translate into symptomatic benefit for patients during activities of daily living . OBJECTIVES We undertook a series of individual r and omized controlled trials ( N-of-1 RCTs ) to measure the effect of oxygen  in patients with COPD who do not meet criteria for mortality reduction with long-term oxygen therapy .  METHODS Twenty-seven patients completed blinded N-of-1 RCTs , each comprising three pairs of 2-week home treatment periods , with oxygen provided during one period of each pair and a placebo mixture during the other . MEASUREMENTS AND MAIN RESULTS Patients completed the Chronic Respiratory Question naire ( CRQ ) , the St. George 's Respiratory Question naire , and a home five-minute-walk test at the end of each period . We defined a positive response as a CRQ dyspnea score greater ( less dyspnea ) on oxygen than placebo 
    Output:
    
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 .