Ambulatory oxygen for chronic obstructive pulmonary disease

Human blood metabolites and risk of post-traumatic stress disorder: A Mendelian randomization study

BACKGROUND

Post-traumatic stress disorder (PTSD) is a debilitating chronic mental disorder that leads to reduced quality of life and increased economic burden. Observational studies have found an association between human blood metabolites and PTSD. Nonetheless, these studies have limitations and are subject to confounding factors as well as reverse causation. Herein, we employed a two-sample Mendelian randomization (MR) approach for the systematic analysis of the blood metabolites and PTSD causal link.

METHODS

Data for the human blood metabolome, cerebrospinal fluid (CSF) metabolome, and PTSD were obtained from publicly available summary-level genome-wide association studies (GWAS), respectively. The inverse variance weighted (IVW) approach represented the main analytic method for assessing exposure-outcome causal associations, employing multiple sensitivity analyses to verify the results' stability. In addition, replication and meta-analysis, steiger test and reverse MR analysis methods were performed to clarify further that these metabolites have independent causal effects on PTSD. Finally, the results of blood and CSF metabolomics analyses were synthesized to obtain biological markers with a causal link to PTSD.

RESULTS

Conclusively, we identified potential causal associations between six blood metabolites and PTSD. The sensitivity analyses elucidated the absence of pleiotropy or heterogeneity in the MR results. The Steiger test and reverse MR analysis did not reveal reverse causal associations, proving the robustness of our results. Combined blood and CSF metabolome analyses showed the same trend for theophylline.

CONCLUSION

This study reveals a strong causal link between metabolites and PTSD, which can be used as a biomarker for clinical PTSD disease screening and prevention. This study also provides a new perspective on the mechanism of metabolite-mediated PTSD development by combining genomics and metabolomics.

A telephone-based survey of current trends, habits and beliefs in patients receiving portable oxygen therapy in Madrid, Spain

Portable oxygen therapy is a major challenge for patients and clinicians. Additionally, the available evidence on this subject is poor considering that only a few studies have been published and the results have not been encouraging. We explored the current trends, habits and beliefs among patients receiving portable oxygen therapy in a geographical area of Madrid, Spain (4 051 862 inhabitants). A telephone-based survey was conducted among patients selected from a database who were undergoing portable oxygen therapy. The number of patients on home respiratory therapies on December 31, 2017 was 81 559 (prevalence 2013.30 per 100 000 inhabitants). A total of 19 492 patients were on home oxygen therapy (HOT) (prevalence 481.16 per 100 000 inhabitants). Of these, 4015 patients (20% of the total of patients on HOT) received ambulatory oxygen therapy. In the analysed period, 1942 patients were selected (57.31% male and 42.69% female). The mean±sd age was 73.89±11.67 years. Most of patients had portable oxygen concentrators (99.59%). The survey was completed by 1777 patients. Most of patients thought they had been prescribed HOT for respiratory failure. 55% of the participants surveyed reported having carried out a walking test with oxygen to know the amount of oxygen they needed. 71% of the participants reported leaving the home for between 1 and 3 h a day. Most of them were carrying portable devices in a wheeled cart (51.94%). Our study data obtained from a large sample of oxygen-dependent individuals provide valuable information regarding domiciliary and portable oxygen usage in Madrid.

The debate on continuous home oxygen therapy

Two studies published in the early 80s, namely the Nocturnal Oxygen Therapy Trial (NOTT) and the Medical Research Council Trial (MRC), laid the foundations for modern home oxygen therapy. Since then, little progress has been made in terms of therapeutic indications, and several prescription-associated problems have come to light. Advances in technology have gone hand in hand with growing disregard for the recommendations in clinical guidelines on oxygen therapy. The introduction of liquid oxygen brought with it a number of technical problems, clinical problems related to selecting candidate patients for portable delivery devices, and economic problems associated with the rising cost of the therapy. Continuous home oxygen therapy has been further complicated by the recent introduction of portable oxygen concentrators and the development in quick succession of a range of delivery devices with different levels of efficiency and performance. Modern oxygen therapy demands that clinicians evaluate the level of mobility of their patients and the mobility permitted by available oxygen sources, correctly match patients with the most appropriate oxygen source and adjust the therapy accordingly. The future of continuous home oxygen therapy lies in developing the ideal delivery device, improving the regulations systems and information channels, raise patient awareness and drive research.

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.

The Design and Development of a New Light-Weight Portable Oxygen System

Background: Patients with respiratory disorders such as chronic obstructive pulmonary disease (COPD) are prescribed oxygen therapy, but frequently fail to use it as intended and therefore do not receive the associated health benefits. Many of the reasons for this non adherence to therapy relate to the design of the equipment currently provided. We have designed and developed a novel system for portable oxygen delivery to overcome this problem. Method of Approach: There were five complementary workpackages (user involvement and exploratory work; ultra lightweight cylinder technology; embedded valve regulator technology; patient-driven system design; regulatory design & manufacturing review). Each had specific deliverables supporting the end point of the program, i.e., to have a fully functioning prototype oxygen delivery system that had been designed and evaluated with maximum input from end users. Results: Patients primarily wanted a lightweight, long lasting, reliable, unobtrusive and ergonomically designed system with simple controls. To provide this, we have developed a new full wrap composite cylinder that has achieved weight savings of ∼12% over a comparative composite cylinder, or a doubling in cylinder design life. We have developed a totally new concept in valve regulator technology, conferring significant reductions in weight and space envelope. We have addressed form factor, flow dial design and flow setting indicator design to improve the ergonomics and esthetics of the system. The developed prototype system weighs 1.7 kg when full, is 34.2 cm in height and 8.5–8.7 cm in diameter, and is capable of 8 h operation at a flow rate of 2 liters per minute, using a standard conserver. Conclusions: Throughout this project, a significant amount of time was invested in establishing the views and perceptions of potential end-users of the new system. This has ensured that their views informed the design and development process. By combining novel cylinder technology with revolutionary valve technology (SmartFlow) we have been able to design an ultra-light cylinder oxygen system (IOS®) with accurate, reliable and stable flow. The weight reduction combined with the new easy-to-read gauge and user-friendly controls should improve patient confidence in the system and result in increased adherence to therapy.

An integrative review of systematic reviews related to the management of breathlessness in respiratory illnesses

BACKGROUND

Breathlessness is a debilitating and distressing symptom in a wide variety of diseases and still a difficult symptom to manage. An integrative review of systematic reviews of non-pharmacological and pharmacological interventions for breathlessness in non-malignant disease was undertaken to identify the current state of clinical understanding of the management of breathlessness and highlight promising interventions that merit further investigation.

METHODS

Systematic reviews were identified via electronic databases between July 2007 and September 2009. Reviews were included within the study if they reported research on adult participants using either a measure of breathlessness or some other measure of respiratory symptoms.

RESULTS

In total 219 systematic reviews were identified and 153 included within the final review, of these 59 addressed non-pharmacological interventions and 94 addressed pharmacological interventions. The reviews covered in excess of 2000 trials. The majority of systematic reviews were conducted on interventions for asthma and COPD, and mainly focussed upon a small number of pharmacological interventions such as corticosteroids and bronchodilators, including beta-agonists. In contrast, other conditions involving breathlessness have received little or no attention and studies continue to focus upon pharmacological approaches. Moreover, although there are a number of non-pharmacological studies that have shown some promise, particularly for COPD, their conclusions are limited by a lack of good quality evidence from RCTs, small sample sizes and limited replication.

CONCLUSIONS

More research should focus in the future on the management of breathlessness in respiratory diseases other than asthma and COPD. In addition, pharmacological treatments do not completely manage breathlessness and have an added burden of side effects. It is therefore important to focus more research on promising non-pharmacological interventions.

Effect of Oxygen on Health Quality of Life in Patients with Chronic Obstructive Pulmonary Disease with Transient Exertional Hypoxemia

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 randomized 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 Questionnaire (CRQ), the St. George's Respiratory Questionnaire, 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 during all three pairs of treatment periods, with a difference >or= 0.5 inches for at least two treatment pairs. Oxygen significantly increased the five-minute-walk test (427 vs. 412 steps, p = 0.04). Two of 27 patients met the responder criteria. Among the whole group, neither the CRQ nor the St. George's Respiratory Questionnaire showed any statistical or clinical differences between oxygen and placebo.

CONCLUSIONS

This study does not support the general application of long-term ambulatory oxygen therapy for patients with COPD who do not meet criteria for mortality reduction with long-term oxygen therapy. N-of-1 RCTs can identify patients who may 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.

Adult domiciliary oxygen therapy. Position statement of the Thoracic Society of Australia and New Zealand

Patients with chronic obstructive pulmonary disease and a stable daytime PaO2 of < or = 55 mmHg (7.3 kPa) live longer and have a better quality of life if provided with long-term continuous oxygen therapy. It is reasonable to offer continuous oxygen therapy also to patients with other lung diseases that cause chronic hypoxaemia. Indications for supplemental oxygen therapy during exercise (ambulatory oxygen therapy) and sleep (nocturnal oxygen therapy) are less clear.