An evaluation of short-term oxygen therapy: the prescription of oxygen to patients with chronic lung disease hypoxic at discharge from hospital

Severe COVID-19 with persistent respiratory failure—A retrospective cohort study in a tertiary centre in Malaysia

Introduction

Management of severe COVID-19 patients with persistent respiratory failure after acute phase treatment is not only challenging, but evidence for treatment is scarce, despite some authors reporting favourable clinical responses to corticosteroid therapy in histologically proven secondary organising pneumonia (OP). This study aimed to report the course of the disease, radiological pattern and clinical outcomes of severe COVID-19 patients with persistent respiratory failure.

Methods

This was a retrospective cohort study of severe COVID-19 patients who were admitted to a single tertiary centre from 1 January 2021 to 30 June 2021. The clinical data of the patients during admission and clinic follow-up, including radiological images, were traced using electronic medical records.

Results

In our cohort, the mortality rate for those with severe COVID-19 was 23.1% (173/749). Among the survivors, 46.2% (266/576) had persistent respiratory failure (PRF) after 14 days of illness. Of them, 70.3% (187/266) were followed up, and 68% (128/187) received oral corticosteroid (prednisolone) maintenance treatment. OP pattern made up the majority (81%) of the radiological pattern with a mean severity CT score of 10 (SD±3). The mean prednisolone dose was 0.68mg/kg/day with a mean treatment duration of 47 days (SD±18). About one-third of patients (67/187) had respiratory symptoms at 4 weeks (SD±3). Among 78.1% (146/187) who had a repeated CXR during follow-up, only 12 patients (8.2%, SD±3) had radiological improvement of less than 50% at 6 weeks (SD±3), with 2 of them later diagnosed as pulmonary tuberculosis. Functional assessments, such as the 6-minute walk test and the spirometry, were only performed in 52.4% and 15.5% of the patients, respectively.

Conclusion

Almost half of the patients with severe COVID-19 had PRF, with a predominant radiological OP pattern. More than two-thirds of the PRF patients required prolonged oral corticosteroid treatment. Familiarising clinicians with the disease course, radiological patterns, and potential outcomes of this group of patients may better equip them to manage their patients.

Short-Term Oxygen Therapy Outcomes in COPD

Rationale

Short-term oxygen therapy (STOT) is often prescribed to allow patients with chronic obstructive pulmonary disease (COPD) to be discharged safely from hospital following an acute illness. This practice is widely accepted without being based on evidence.

Purpose

Our objective was to describe the characteristics and outcomes of patients with COPD who received STOT.

Patients and Methods

The study was a secondary analysis of the INOX trial, a 4-year randomised trial of nocturnal oxygen in COPD. The trial indicated that nocturnal oxygen has no significant effect on survival or progression to LTOT, allowing our merging of patients who received nocturnal oxygen and those who received placebo into a single cohort to study the predictors and outcomes of STOT regardless of the treatment received during the trial.

Results

Among the 243 participants in the trial, 60 required STOT on at least one occasion during follow-up. Patients requiring STOT had more severe dyspnoea and lung function impairment, and lower PaO₂ at baseline than those who did not. STOT was associated with subsequent LTOT requirement (hazard ratio [HR]: 4.59; 95% confidence interval [CI]: 2.98–7.07) and mortality (HR: 1.93; 95% CI: 1.15–3.24). The association between STOT and mortality was confounded by age, disease severity and comorbidities. Periods of STOT of more than one month and/or repeated prescriptions of STOT increased the probability of progression to LTOT (OR: 5.07; 95% CI: 1.48–18.8).

Conclusion

Following an acute respiratory illness in COPD, persistent hypoxaemia requiring STOT is a marker of disease progression towards the requirement for LTOT.

Reassessment of Home Oxygen Prescription after Hospitalization for Chronic Obstructive Pulmonary Disease. A Potential Target for Deimplementation

Rationale: Hypoxemia associated with acute exacerbations of chronic obstructive pulmonary disease (COPD) often resolves with time. Current guidelines recommend that patients recently discharged with supplemental home oxygen after hospitalization should not have renewal of the prescription without assessment for hypoxemia. Understanding patterns of home oxygen reassessment is an opportunity to improve quality and value in home oxygen prescribing and may provide future targets for deimplementation.Objectives: We sought to measure the frequency of home oxygen reassessment within 90 days of hospitalization for COPD and determine the potential population eligible for deimplementation.Methods: We performed a cohort study of patients ≥40 years hospitalized for COPD at five Veterans Affairs facilities who were prescribed home oxygen at discharge. Our primary outcome was the frequency of reassessment within 90 days by oxygen saturation (Sp_O2) measurement. Secondary outcomes included the proportion of patients potentially eligible for discontinuation (Sp_O2 > 88%) and patients in whom oxygen was discontinued. Our primary exposures were treatment with long-acting bronchodilators, prior history of COPD exacerbation, smoking status, and pulmonary hypertension. We used a mixed-effects Poisson model to measure the association between patient-level variables and our outcome, clustered by site. We also performed a positive deviant analysis using chart review to uncover system processes associated with high-quality oxygen prescribing.Results: A total of 287 of 659 (43.6%; range 24.8-78.5% by site) patients had complete reassessment within 90 days. None of our patient-level exposures were associated with oxygen reassessment. Nearly half of those with complete reassessment were eligible for discontinuation on the basis of Medicare guidelines (43.2%; n = 124/287). When using the newest evidence available by the Long-Term Oxygen Treatment Trial, most of the cohort did not have resting hypoxemia (84.3%; 393/466) and would be eligible for discontinuation. The highest-performing Veterans Affairs facility had four care processes to support oxygen reassessment and discontinuation, versus zero to one at all other sites.Conclusions: Fewer than half of patients prescribed home oxygen after a COPD exacerbation are reassessed within 90 days. New system processes supporting timely reassessment and discontinuation of unnecessary home oxygen therapy could improve the quality and value of care.

Home Oxygen Therapy for Adults with Chronic Lung Disease. An Official American Thoracic Society Clinical Practice Guideline

Background: Evidence-based guidelines are needed for effective delivery of home oxygen therapy to appropriate patients with chronic obstructive pulmonary disease (COPD) and interstitial lung disease (ILD).Methods: The multidisciplinary panel created six research questions using a modified Delphi approach. A systematic review of the literature was completed, and the Grading of Recommendations Assessment, Development and Evaluation approach was used to formulate clinical recommendations.Recommendations: The panel found varying quality and availability of evidence and made the following judgments: 1) strong recommendations for long-term oxygen use in patients with COPD (moderate-quality evidence) or ILD (low-quality evidence) with severe chronic resting hypoxemia, 2) a conditional recommendation against long-term oxygen use in patients with COPD with moderate chronic resting hypoxemia, 3) conditional recommendations for ambulatory oxygen use in patients with COPD (moderate-quality evidence) or ILD (low-quality evidence) with severe exertional hypoxemia, 4) a conditional recommendation for ambulatory liquid-oxygen use in patients who are mobile outside the home and require >3 L/min of continuous-flow oxygen during exertion (very-low-quality evidence), and 5) a recommendation that patients and their caregivers receive education on oxygen equipment and safety (best-practice statement).Conclusions: These guidelines provide the basis for evidence-based use of home oxygen therapy in adults with COPD or ILD but also highlight the need for additional research to guide clinical practice.

Home Oxygen in Chronic Obstructive Pulmonary Disease

Two landmark trials conducted more than 35 years ago provided scientific evidence that, under very specific circumstances, long-term oxygen therapy (LTOT) may prolong life. These two trials enrolled 290 patients with chronic obstructive pulmonary disease and severe daytime hypoxemia documented by direct arterial blood gas measurement. From that time, LTOT became a standard of care, and the indications for oxygen therapy expanded to include nocturnal oxygen therapy for isolated nocturnal oxygen desaturation, ambulatory oxygen to correct exercise-induced desaturation, and short-burst oxygen to relieve dyspnea. In most cases, the rationale for broadening the indications for oxygen therapy is that, if hypoxemia exists, correcting it by increasing the Fi_O2 should help. However, with the exception of LTOT in severely hypoxemic patients with chronic obstructive pulmonary disease, randomized controlled trials of oxygen therapy have failed to demonstrate clinically significant benefits. Also, adherence to LTOT is usually suboptimal. Important areas for future research include improving understanding of the mechanisms of action of supplemental oxygen, the clinical and biochemical predictors of responsiveness to LTOT, the methods for measuring and enhancing adherence to LTOT, and the cost-effectiveness of oxygen therapy. A standardization of terminology to describe the use of supplemental oxygen at home is provided.

Characteristics of patients who progress from bridging to long-term oxygen therapy

BACKGROUND

Patients with persistent hypoxia following an acute hospital admission may be discharged with 'bridging' domiciliary oxygen as per criteria defined by the Thoracic Society of Australia and New Zealand. The need for continuous long-term oxygen therapy (LTOT) is then reassessed at a clinic review 1-2 months later.

AIM

To describe the characteristics of patients discharged from an acute hospital admission with continuous short-term oxygen therapy (STOT), and subsequently to investigate for differences between subjects who proceeded to qualify for continuous LTOT versus those who were able to cease STOT at review.

METHODS

This is a retrospective cohort study involving all subjects discharged from Alfred Health between 2011 and 2015 inclusive with bridging domiciliary oxygen. Multiple biochemical, physiological and demographic characteristics were collated and analysed.

RESULTS

Of all patients prescribed continuous STOT at time of discharge, 47.3% qualified for LTOT at outpatient review. This cohort had a significantly lower PaO₂ measurement at time of discharge, compared with those who no longer qualified.

CONCLUSION

PaO₂ at time of discharge provides a signal with the potential to identify who will require continuous LTOT following an acute hospital admission. Additionally, this study highlights the need to re-evaluate patients' oxygen requirements during a period of clinical stability.

E-cigarette use in patients receiving home oxygen therapy

Current smokers who are prescribed home oxygen may not benefit from the therapy. In addition to being an obvious fire hazard, there is some evidence that the physiological mechanisms by which home oxygen is believed to operate are inhibited by smoking. Although their effectiveness is yet to be demonstrated, electronic cigarettes (e-cigarettes) are often regarded as an aid to smoking cessation. However, several burn accidents in e-cigarette smokers receiving home oxygen therapy have also been reported, leading Health Canada to release a warning of fire risk to oxygen therapy patients from e-cigarettes. It is the authors' position that patients receiving oxygen should definitely not use e-cigarettes. The authors provide suggestions for addressing the delicate issue of home oxygen therapy in current cigarette and⁄or e-cigarette smokers.

How do respiratory patients perceive oxygen therapy? A critical interpretative synthesis of the literature

Oxygen therapy is a common intervention in health care worldwide; yet, despite universal use, it is evident through poor practice that oxygen is often prescribed and administered injudiciously. It is proposed that possibly an influencing culture presides, whereby oxygen is often poorly understood and uncertainty regarding its use exists. It is unclear where the origins of this culture lie but exploring perceptions may enlighten the problem. A review of the literature was undertaken to establish what is already known about this elusive phenomenon. The paucity of any direct evidence regarding perceptions of oxygen directed the review to utilize a critical interpretative synthesis (CIS). The aim of this study was to explore how respiratory patients perceive oxygen therapy. A systematic search in Medline, Cinahl, Embase, British Nursing Index and PsychInfo yielded 1514 studies of which 42 were selected to consider the review question. The CIS allowed evidence from across studies to synthesize existing and new interpretations of data related to patients' perceptions of oxygen therapy. Synthetic constructs then informed the synthesizing arguments, namely positive - feeling safe, enabler and comforter; negative - fear, oxygen versus self, restriction and embarrassment; and impartiality - mixed blessings. The findings are divergent, and at times contradictory. There appears uncertainty among patients regarding the purpose and benefits of oxygen therapy, though an underlying faith in health-care professionals is apparent. This faith seems to foster acceptance of a life-changing therapy, despite the impact, burden and incomplete understanding. There is a clear need for further research regarding these elusive perceptions in order to improve clinical practice in respect of oxygen.

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.

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.

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.

Short-term ambulatory oxygen for chronic obstructive pulmonary disease

BACKGROUND

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

OBJECTIVES

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

SEARCH STRATEGY

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

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.

Short term ambulatory oxygen for chronic obstructive pulmonary disease

BACKGROUND

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

OBJECTIVES

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

SEARCH STRATEGY

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Continuous Oxygen Therapy for Hypoxic Pulmonary Disease

Continuous oxygen therapy (COT) has become widely accepted in the last 20 years in patients with continuous hypoxemia. This review focuses on guidelines for COT, adherence to these guidelines, and the effect of COT on survival, hospitalization, and quality of life. Guidelines for COT are mainly based on three randomized studies where documentation of hypoxemia (P(a)O2 <60mm Hg) and administration of oxygen at least 15 hours/day, are essential. There is less certainty concerning the required correction for hypoxemia, the attitude against current smokers with hypoxemia, the frequency and methods of follow up, and the effect of prescribing domiciliary oxygen to patients with temporary hypoxemia due to a clinically unstable condition (i.e. short-term oxygen therapy [STOT]). The administration of COT to patients with hypoxemic conditions other than COPD rests on extrapolation of data from COPD patients in the NOTT (Nocturnal Oxygen Therapy Trial) and MRC (British Medical Research Council) studies. Adherence to these guidelines is low in general, and very low in some cases. In some countries, STOT accounts for the majority of all prescriptions of domiciliary oxygen, and because nearly half of these patients do not meet the hypoxemia criteria at 3-month follow-up, re-evaluation is mandatory. Only 35%, approximately, of the patients are followed up, and this is one of the main reasons for poor adherence to the hypoxemia criteria. In order to improve the quality of surveillance of COT, more effort has to be put into education of the patients and staff responsible for COT, centralization of the domiciliary organizations, better equipment for ambulation and traveling, and regular follow-up preferably with home visits. The role of an oxygen register on the quality of surveillance of COT has to be determined. The beneficial effect of COT on survival is well established, and some evidence suggests that COT reduces hospitalization. It appears that ambulatory oxygen from liquid source or lightweight cylinders improves disease-specific quality of life modestly in selected patients who partake in regular outdoor activity. Whether COT from oxygen concentrators improves quality of life significantly is, at present, less clear.

Long-term oxygen therapy improves health-related quality of life

Guidelines for the prescription of long-term oxygen therapy (LTOT) in hypoxemic COPD patients are based on two landmark studies in which survival was the primary outcome. Such patients are importantly symptomatic with poor health-related quality of life (HRQL) but the effect of LTOT on HRQL remains uncertain. We undertook a prospective longitudinal interventional study of consecutive COPD patients referred to our regional oxygen service; n = 43 fulfilling criteria and commenced on LTOT, n = 25 not fulfilling criteria and continued on standard care. HRQL was measured at baseline, 2 and 6 months. Both patient groups had severe COPD as defined by mean FEV1 < 35% predicted. At baseline the LTOT group demonstrated significantly worse HRQL as defined by the Chronic Respiratory Questionnaire (CRQ) (fatigue, emotional function, mastery and total scores), total generic Dartmouth COOP Charts and anxiety domain of the Hospital Anxiety and Depression scale. Significant improvements in HRQL were noted at 2 and 6 months in the LTOT group. Conversely the non-LTOT group demonstrated a progressive decline in HRQL. Using validated criteria for a minimal clinically significant improvement in CRQ, there were 28 (67%) and 26 (68%) 'responders' at 2 and 6 months respectively in the LTOT group. The introduction of LTOT to patients with severe COPD fulfilling standard criteria was associated with early significant improvements in HRQL with sustained or further response at 6 months.