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

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

OBJECTIVE

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

DESIGN

Retrospective study.

SETTING

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

PARTICIPANTS

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

INTERVENTIONS

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

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSION

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

Pragmatic randomised controlled trial of a personalised intervention for carers of people requiring home oxygen therapy

We used a pragmatic randomised controlled trial to evaluate a behavioural change strategy targeting carers of chronically hypoxaemic patients using long-term home oxygen therapy. Intervention group carers participated in personalised educational sessions focusing on motivating carers to take actions to assist patients. All patients received usual care. Effectiveness was measured through a composite event of patient survival to hospitalisation, residential care admission or death to 12 months. Secondary outcomes at baseline, 3, 6 and 12 months included carer and patient emotional and physical well-being. No difference between intervention (n = 100) and control (n = 97) patients was found for the composite outcome (hazard ratio (HR) 1.22, 95% confidence interval (CI) = 0.89, 1.68; p = 0.22). Improved fatigue, mastery, vitality and general health occurred in intervention group patients (all p values < 0.05). No benefits were seen in carer outcomes. Mortality was significantly higher in intervention patients (HR = 2.01, 95% CI = 1.00, 4.14; p = 0.05; adjusted for Australia-modified Karnofsky Performance Status), with a significant diagnosis-intervention interaction (p = 0.028) showing higher mortality in patients with COPD (HR 4.26; 95% CI = 1.60, 11.35) but not those with interstitial lung disease (HR 0.83; 95% CI = 0.28, 2.46). No difference was detected in the primary outcome, but patient mortality was higher when carers had received the intervention, especially in the most disabled patients. Trials examining behavioural change interventions in severe disease should stratify for functionality, and both risks and benefits should be independently monitored. Trial registration: Australian New Zealand Clinical Trials Registry (ACTRN12607000177459).

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.

Nose to the grindstone: The hidden dangers of long-term oxygen therapy

This case report describes an unusual complication of a patient with chronic obstructive pulmonary disease using long-term oxygen therapy and discusses the importance of regular education and surveillance of patients when prescribing this treatment modality.

Oxygen therapy for COPD

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

Pulmonary hypertension and right heart dysfunction in chronic lung disease

Group 3 pulmonary hypertension (PH) is a common complication of chronic lung disease (CLD), including chronic obstructive pulmonary disease (COPD), interstitial lung disease, and sleep-disordered breathing. Development of PH is associated with poor prognosis and may progress to right heart failure, however, in the majority of the patients with CLD, PH is mild to moderate and only a small number of patients develop severe PH. The pathophysiology of PH in CLD is multifactorial and includes hypoxic pulmonary vasoconstriction, pulmonary vascular remodeling, small vessel destruction, and fibrosis. The effects of PH on the right ventricle (RV) range between early RV remodeling, hypertrophy, dilatation, and eventual failure with associated increased mortality. The golden standard for diagnosis of PH is right heart catheterization, however, evidence of PH can be appreciated on clinical examination, serology, radiological imaging, and Doppler echocardiography. Treatment of PH in CLD focuses on management of the underlying lung disorder and hypoxia. There is, however, limited evidence to suggest that PH-specific vasodilators such as phosphodiesterase-type 5 inhibitors, endothelin receptor antagonists, and prostanoids may have a role in the treatment of patients with CLD and moderate-to-severe PH.

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.

WITHDRAWN: Oxygen therapy for dyspnoea in adults

This review is out of date, and the original author team were not available to update this review, hence the review has been withdrawn.

The editorial group responsible for this previously published document have withdrawn it from publication.

Clinical use of pulse oximetry: official guidelines from the Thoracic Society of Australia and New Zealand

Pulse oximetry provides a simple, non-invasive approximation of arterial oxygenation in a wide variety of clinical settings including emergency and critical-care medicine, hospital-based and ambulatory care, perioperative monitoring, inpatient and outpatient settings, and for specific diagnostic applications. Pulse oximetry is of utility in perinatal, paediatric, adult and geriatric populations but may require use of age-specific sensors in these groups. It plays a role in the monitoring and treatment of respiratory dysfunction by detecting hypoxaemia and is effective in guiding oxygen therapy in both adult and paediatric populations. Pulse oximetry does not provide information about the adequacy of ventilation or about precise arterial oxygenation, particularly when arterial oxygen levels are very high or very low. Arterial blood gas analysis is the gold standard in these settings. Pulse oximetry may be inaccurate as a marker of oxygenation in the presence of dyshaemoglobinaemias such as carbon monoxide poisoning or methaemoglobinaemia where arterial oxygen saturation values will be overestimated. Technical considerations such as sensor position, signal averaging time and data sampling rates may influence clinical interpretation of pulse oximetry readings.

Multicentre audit of inpatient management of acute exacerbations of chronic obstructive pulmonary disease: comparison with clinical guidelines

BACKGROUND AND OBJECTIVE

Chronic obstructive pulmonary disease (COPD) exacerbations are a major cause of hospital admission and clinical guidelines for optimised management are available. However, few data assessing concordance with these guidelines are available. We aimed to identify gaps and document variability in clinical practices for COPD admissions.

METHODS

Medical records of all admissions over a 3-month period as COPD with non-catastrophic or severe comorbidities or complications at eight acute-care hospitals within the Hunter New England region were retrospectively audited.

RESULTS

Mean (SD) length of stay was 6.3 (6.1) days for 221 admissions with mean age of 71 (10), 53% female and 34% current smokers. Spirometry was performed in 34% of admissions with a wide inter-hospital range (4-58%, P < 0.0001): mean FEV1 was 36% (18) predicted. Arterial blood gases were performed on admission in 54% of cases (range 0-85%, P < 0.0001). Parenteral steroids were used in 82% of admissions, antibiotics in 87% and oxygen therapy during admission in 79% (with oxygen prescription in only 3% of these). Bronchodilator therapy was converted from nebuliser to an inhaler device in 51% of cases early in admission at 1.6 (1.7) days. Only 22% of patients were referred to pulmonary rehabilitation (inter-hospital range of 0-50%, P = 0.002). Re-admission within 28 days was higher in rural hospitals compared with metropolitan (27% vs 7%, P < 0.0001).

CONCLUSIONS

We identified gaps in best practice service provision associated with wide inter-hospital variations, indicating disparity in access to services throughout the region.

Inability of single resting arterial blood gas to predict significant hypoxaemia in chronic obstructive pulmonary disease

BACKGROUND

While point measurement of resting arterial partial pressure of oxygen (P(a)O(2)) is the traditional gold-standard for assessment of oxygenation in chronic obstructive pulmonary disease (COPD), 24-h oximetry may identify further patients with clinically significant hypoxaemia. We aimed to describe the relationship between these two parameters and identify other correlated variables.

METHODS

All patients registered with the Barwon Health Hospital Admission Risk Program from 1 March to 31 October 2008 for the diagnosis of COPD were identified. The main inclusion criteria were obstructive spirometry, clinical stability and moderate resting hypoxaemia (P(a)O(2) 56-70 mmHg). All patients underwent 24-h oximetry, arterial blood gas, spirometry, anthropometry and telephone questionnaire, and 23 patients also completed polysomnography.

RESULTS

Inclusion criteria were met in 35 of 287 patients. Mean recording time was 23.5 h, representing 97% of intended oximetry time. Nineteen patients (54%) spent greater than 30% of recorded oximetry time below 90%. There was a moderate inverse correlation between time below 90% saturations and P(a)O(2) (r=-0.40, P= 0.02), with body mass index (BMI) the only other independent predictor of the primary outcome identified (r= 0.39, P= 0.02). Correlations were similar for waking hours considered separately. However, for sleeping oximetry, BMI and age were the only independent predictors of time below 90%. Polysomnography demonstrated a high prevalence of rapid eye movement-related hypoventilation and obstructive sleep apnoea syndrome.

CONCLUSIONS

Many patients with moderate hypoxaemia on resting P(a)O(2) desaturate significantly on ambulatory oximetry. The correlation between P(a)O(2) and proportion of saturations below 90% is moderate and similar to BMI, but this pattern does not hold during sleeping hours.

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.

The clinical and social dimensions of prescribing palliative home oxygen for refractory dyspnea

BACKGROUND

Chronic breathlessness is a significant problem in palliative care and oxygen is often prescribed in an attempt to ameliorate it. Often, this prescription falls outside the current funding guidelines for long-term home oxygen use. The aim of this qualitative study was to understand the factors that most influence Australian specialist palliative care nurses' initiation of home oxygen for their patients.

METHODS

A series of focus groups were held across three states in Australia in 2011 involving specialist palliative care nurses. The invitation to the nurses was sent by e-mail through their national association. Recorded and transcribed data were coded for themes and subthemes. A summary, which included quotes, was provided to participants to confirm.

RESULTS

Fifty-one experienced palliative care nurses participated in seven focus groups held in three capital cities. Two major themes were identified: 1) logistic/health service issues (not reported in this paper as specific to the Australian context) involving the local context of prescribing and, 2) clinical care issues that involved assessing the patient's need for home oxygen and ongoing monitoring concerns. Palliative care nurses involved in initiating or prescribing oxygen often reported using oxygen as a second-line treatment after other interventions had been trialed and these had not provided sufficient symptomatic benefit. Safety issues were a universal concern and a person living alone did not emerge as a specific issue among the nurses interviewed.

CONCLUSION

The role of oxygen is currently seen as a second-line therapy in refractory dyspnea by specialist palliative care nurses.

Extent of disease on high-resolution computed tomography lung is a predictor of decline and mortality in systemic sclerosis-related interstitial lung disease

OBJECTIVES

In a multi-centre study, we sought to determine whether extent of disease on high-resolution CT (HRCT) lung, reported using a simple grading system, is predictive of decline and mortality in SSc-related interstitial lung disease (SSc-ILD), independently of pulmonary function tests (PFTs) and other prognostic variables.

METHODS

SSc patients with a baseline HRCT performed at the time of ILD diagnosis were identified. All HRCTs and PFTs performed during follow-up were retrieved. Demographic and disease-related data were prospectively collected. HRCTs were graded according to the percentage of lung disease: >20%: extensive; <20%: limited; unclear: indeterminate. Indeterminate HRCTs were converted to limited or extensive using a forced vital capacity threshold of 70%. The composite outcome variable was deterioration (need for home oxygen or lung transplantation), or death.

RESULTS

Among 172 patients followed for mean (s.d.) of 3.5 (2.9) years, there were 30 outcome events. In Weibull multivariable hazards regression modelling, baseline HRCT grade was independently predictive of outcome, with an adjusted hazard ratio (aHR) = 3.0, 95% CI 1.2, 7.5 and P = 0.02. In time-varying covariate models (based on 1309 serial PFTs and 353 serial HRCTs in 172 patients), serial diffusing capacity of the lung for carbon monoxide by alveolar volume ratio (ml/min/mmHg/l) (aHR = 0.4; 95% CI 0.3, 0.7; P = 0.001) and forced vital capacity (dl) (aHR = 0.9; 95% CI 0.8, 0.97; P = 0.008), were also strongly predictive of outcome.

CONCLUSION

Extensive disease (>20%) on HRCT at baseline, reported using a semi-quantitative grading system, is associated with a three-fold increased risk of deterioration or death in SSc-ILD, compared with limited disease. Serial PFTs are informative in follow-up of patients.

Resolving moral distress when caring for patients who smoke while using home oxygen therapy

More than 1 million people in the United States use home oxygen therapy and its demand is growing. However, there are dangers associated with its use, such as burns and home fires, and smoking is the most common cause of these incidents. As a result, home healthcare nurses feel intense emotional distress when caring for patients who smoke while using home oxygen therapy. This distress arises from the nurse's competing sense of moral duties toward these patients. The purpose of this article is to describe this distress, then to propose a 3-step process of taking concrete actions to resolve the distress.

Does palliative home oxygen improve dyspnoea? A consecutive cohort study

Palliative oxygen for refractory dyspnoea is frequently prescribed, even when the criteria for long-term home oxygen (based on survival, rather than the symptomatic relief of breathlessness) are not met. Little is known about how palliative home oxygen affects symptomatic breathlessness. A 4-year consecutive cohort from a regional community palliative care service in Western Australia was used to compare baseline breathlessness before oxygen therapy with dyspnoea sub-scales on the symptom assessment scores (SAS; 0-10) 1 and 2 weeks after the introduction of oxygen. Demographic and clinical characteristics of people who responded were included in a multi-variable logistic regression model. Of the study population (n = 5862), 21.1% (n = 1239) were prescribed oxygen of whom 413 had before and after data that could be included in this analysis. The mean breathlessness before home oxygen was 5.3 (SD 2.5; median 5; range 0-10). There were no significant differences overall at 1 or 2 weeks (P = 0.28) nor for any diagnostic sub-groups. One hundred and fifty people (of 413) had more than a 20% improvement in mean dyspnoea scores. In multi-factor analysis, neither the underlying diagnosis causing breathlessness nor the demographic factors predicted responders at 1 week. Oxygen prescribed on the basis of breathlessness alone across a large population predominantly with cancer does not improve breathlessness for the majority of people. Prospective randomised trials in people with cancer and non-cancer are needed to determine whether oxygen can reduce the progression of breathlessness compared to a control arm.

Acute oxygen therapy does not improve cognitive and driving performance in hypoxaemic COPD

BACKGROUND AND OBJECTIVE

Cognitive and neuropsychological function may be adversely affected by low blood oxygen levels and this has been previously demonstrated in hypoxaemic COPD. The aim of this study was to assess whether supplemental oxygen therapy while driving a motor vehicle is justified in hypoxaemic COPD. We therefore used computer-based driving simulation to investigate whether acute intranasal oxygen therapy improves the cognitive and driving performance of such patients.

METHODS

Thirty hypoxaemic COPD subjects with a current driving licence performed a 20-min computer-based driving simulation task and a 10-min psychomotor vigilance task (PVT) at baseline, and while breathing intranasal oxygen or intranasal air in a randomized, double-blind, cross-over protocol.

RESULTS

The mean (SD) age of the subjects was 72 years (8) and their mean driving experience was 50 years (10). Mean FEV(1) was 41% (18) of predicted and PaO(2) was 50.5 mm Hg (4.7) on air and 70.7 mm Hg (9.1) on oxygen. There were no statistically significant differences in any measure of driving performance or in reaction time measurements while breathing oxygen compared with air.

CONCLUSIONS

Acute oxygen therapy does not improve simulated driving performance or neurocognitive function as assessed by PVT in patients with hypoxaemic COPD. These data do not support the recommendation that oxygen should be used by this patient group while driving.

Oxygen therapy for dyspnoea in adults

BACKGROUND

Dyspnoea, or distressing breathing, is often a severe subjective symptom in terminal illness and may be difficult to control. Oxygen therapy is currently one of the interventions used to treat it. This review aimed to identify all randomised controlled studies (RCTs) in which oxygen therapy was used as a treatment to relieve dyspnoea in chronic terminal illness, and to synthesize the findings into a conclusion regarding the overall effectiveness of oxygen therapy for the palliation of dyspnoea in chronic terminal illness.

OBJECTIVES

The objective of this review was to determine if oxygen therapy, administered in a non-acute care setting, provided additional relief of dyspnoea in study participants with chronic end-stage disease over that provided by breathing room air or placebo air as a control.

SEARCH STRATEGY

Electronic databases were searched using predefined search terms. Searches were current to April 2006.

SELECTION CRITERIA

Only RCTs were considered for inclusion in this review. Unblinded studies were included.

DATA COLLECTION AND ANALYSIS

Data was extracted by one review author and checked by another.

MAIN RESULTS

Eight studies met the inclusion criteria for the review and included a total of 144 participants (cancer; n = 97, cardiac failure; n = 35, kyphoscoliosis; n = 12). Four cross-over studies, two studies with the participants at rest and two involving exercise testing, compared oxygen inhalation to air inhalation for dyspnoea management in adults with advanced cancer. Three cross-over studies compared the use of oxygen inhalation to air inhalation in adults with stable chronic heart failure for dyspnoea management during exercise testing and one crossover study compared ambulatory oxygen therapy with air inhalation on exercise-induced dyspnoea for study participants with kyphoscoliosis (a sideways and forwards curvature of the spine). No studies with matched or cohort controls were identified. Due to differences in study designs, few studies could be pooled for a meta-analysis. This systematic review of the literature failed to demonstrate a consistent beneficial effect of oxygen inhalation over air inhalation for study participants with dyspnoea due to end-stage cancer or cardiac failure. Some cancer study participants appeared to feel better during oxygen inhalation.

AUTHORS' CONCLUSIONS

The failure to demonstrate a beneficial effect for oxygen breathing over air breathing in cancer or cardiac failure was limited by the small volume of research studies available for inclusion, the small numbers of participants and by the methods used in the studies.

Smoking and home oxygen therapy--a preventable public health hazard

Patients who continue to smoke while on home oxygen therapy endanger themselves, family members, neighbors, and firefighters and create an expense to society for their medical care. This phenomenon was studied in our burn center. Fourteen patients were identified prospectively during the last 2 years. All were smoking while on nasal oxygen. The 14 patients (10 males) were 45 to 87 years of age. All suffered facial burns. Only one patient had a significant burn (30% TBSA, 20% 3rd degree), but all suffered from an exacerbation of chronic obstructive pulmonary disease. Two patients gave a history of stage IV lung cancer and four patients had newly found squamous cell cancer seen on bronchoscopy. All six patients with lung cancer and one with severe chronic obstructive pulmonary disease died. Of the seven survivors, only one patient quit smoking. Total charges were $2,861,526 and total costs were $938,311. All patients had Medicare or Medicaid on admission. Hospital loss ($432,561) was incurred in those patients admitted more than 4 days whereas a profit ($33,285) was realized in patients admitted less than 4 days. These deaths and financial loss could be reduced by better testing and more precise guidelines as to which patients can safely receive home oxygen. Patients can have their saliva tested for the nicotine breakdown product of cotinine; the test takes 10 minutes. The American Burn Association, in conjunction with the American College of Chest Physicians, should address this issue and develop guidelines for physicians who order home oxygen therapy and for state departments of public health who should regulate the companies that deliver home oxygen.

Combined oximetry-cutaneous capnography in patients assessed for long-term oxygen therapy

STUDY AIM

To evaluate the feasibility of combined oximetry (pulse oximetric saturation [Spo(2)]) and cutaneous capnography (transcutaneous carbon dioxide tension [Ptcco(2)]) for oxygen titration in patients requiring long-term oxygen therapy.

METHODS

Twenty patients with obstructive or restrictive lung disease underwent oxygen titration using a combined cutaneous oximetry-capnography sensor. The goal of titration was to achieve an oxygen saturation of > 90% without a significant rise in carbon dioxide. Spo(2) and Ptcco(2) measurements at the end of titration were compared with blood gas levels using Bland-Altman analysis and linear regression analysis.

RESULTS

The mean (+/- SE of the estimate) Pao(2) while breathing room air was 53.2 +/- 8.1 mm Hg and increased to 75.9 +/- 13.3 mm Hg with oxygen supplementation (p < 0.0001). The mean Paco(2) was 45.9 +/- 8.7 mm Hg at baseline and 47.8 +/- 9.0 mm Hg after oxygen titration (p = 0.003). Bland-Altman analysis for comparison of Ptcco(2) and Paco(2) showed a bias of 0.86 mm Hg with a precision of 3.48 mm Hg. Bland-Altman analysis for the comparison of Spo(2) and arterial oxygen saturation showed a bias of 0.14% with a precision of 1.13%.

CONCLUSION

Combined oximetry and cutaneous capnography is feasible during oxygen titration in patients needing long-term oxygen therapy. This noninvasive approach has the potential to reduce the number of arterial blood gas samplings performed.

Human cardiovascular dose-response to supplemental oxygen

AIM

The aim of the study was to examine the central and peripheral cardiovascular adaptation and its coupling during increasing levels of hyperoxaemia. We hypothesized a dose-related effect of hyperoxaemia on left ventricular performance and the vascular properties of the arterial tree.

METHODS

Oscillometrically calibrated arterial subclavian pulse trace data were combined with echocardiographic recordings to obtain non-invasive estimates of left ventricular volumes, aortic root pressure and flow data. For complementary vascular parameters and control purposes whole-body impedance cardiography was applied. In nine (seven males) supine, resting healthy volunteers, aged 23-48 years, data was collected after 15 min of air breathing and at increasing transcutaneous oxygen tensions (20, 40 and 60 kPa), accomplished by a two group, random order and blinded hyperoxemic protocol.

RESULTS

Left ventricular stroke volume [86 +/- 13 to 75 +/- 9 mL (mean +/- SD)] and end-diastolic area (19.3 +/- 4.4 to 16.8 +/- 4.3 cm(2)) declined (P < 0.05), and showed a linear, negative dose-response relationship to increasing arterial oxygen levels in a regression model. Peripheral resistance and characteristic impedance increased in a similar manner. Heart rate, left ventricular fractional area change, end-systolic area, mean arterial pressure, arterial compliance or carbon dioxide levels did not change.

CONCLUSION

There is a linear dose-response relationship between arterial oxygen and cardiovascular parameters when the systemic oxygen tension increases above normal. A direct effect of supplemental oxygen on the vessels may therefore not be excluded. Proximal aortic and peripheral resistance increases from hyperoxaemia, but a decrease of venous return implies extra cardiac blood-pooling and compensatory relaxation of the capacitance vessels.

Domiciliary oxygen therapy services in Tasmania: prescription, usage and impact of a specialist clinic

OBJECTIVE

To assess the use of domiciliary oxygen therapy (DOT) in Tasmania and the impact of a specialist oxygen clinic on service provision.

DESIGN

Retrospective observational study.

PARTICIPANTS AND SETTING

Patients prescribed government-funded DOT in Tasmania between December 2002 and April 2004.

MAIN OUTCOME MEASURES

Indications for DOT; usage, prescription, reassessment and costs of DOT; influence of a specialist-run oxygen clinic.

RESULTS

490 patients were using DOT, an overall rate of 102 patients per 100 000 population (varying between regions from 95 to 116 per 100 000 population). Of 267 patients (54%) prescribed DOT during hospitalisation, only 72% met national guidelines for DOT at commencement. Chronic obstructive pulmonary disease (COPD) was the most common indication (48% of prescriptions). The median time to reassessment after prescription was 5.5 months. Median usage in patients with COPD was 18.3 hours per day. The average cost per patient was $1498 per year, but differed regionally in relation to costs of ambulatory supplies. The oxygen clinic in the north-west region substantially reduced oxygen prescriptions, improved compliance with guidelines, decreased time to first reassessment from 21 to 6.6 months, and produced major cost savings.

CONCLUSIONS

Prescription of DOT was often not in keeping with national guidelines. Reassessment was poor, despite more than half the patients being prescribed DOT as an inpatient. A dedicated oxygen clinic resulted in more appropriate prescription, decreased time to reassessment and a reduction in costs.

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.

Outcomes of adult domiciliary oxygen therapy in pulmonary diseases

Domiciliary oxygen therapy has been used during the last five decades to alleviate hypoxemia and its consequences. It is considered to be one of the most expensive therapeutic methods currently available, but it is also the only therapeutic approach that can prolong survival in patients with chronic hypoxemia. Domiciliary oxygen therapy is also aimed at relieving dyspnea and improving exercise capacity and sleep quality. Portable cylinders, concentrators and portable liquid systems are the main delivery systems currently available and oxygen-conserving devices attached are aimed at improving their effectiveness. In order to minimize the associated costs, appropriate patient selection and reassessment are required. Domiciliary oxygen therapy is mostly prescribed in chronic obstructive pulmonary disease - a disease caused predominantly by smoking and in which airway obstruction results in reduced arterial oxygenation (hypoxemia). Domiciliary oxygen therapy effectiveness is best evaluated and documented in chronic obstructive pulmonary disease, which also accounts for most of its prescriptions. Therefore, this review focuses predominantly on this disease-related oxygen therapy.