Ambulatory Long-Term Oxygen Therapy in Patients with Severe COPD: A Randomized Crossover Trial to Compare Constant-Minute-Volume and Constant-Bolus Systems

Background and Methods

Constant-minute-volume and constant-bolus devices serve as two different means of portable oxygen conservation. A prospective randomised crossover study was conducted in COPD GOLD IV patients to investigate the effect of these two devices on dyspnea, oxygenation and 6-minute walking test (6MWT) distance. The primary endpoint was the final operating level required (operating level range 1-5 for both devices) by either device to meet the success criteria for mobile oxygen therapy, as outlined in the British Thoracic Society guidelines (SpO2 ≥90% throughout 6MWT; ≥10% increase in walking distance from baseline; improvement in BORG of at least 1 point from baseline).

Results

Twenty-five patients were enrolled in the study and randomly assigned to one of two sequences involving the use of each type of portable oxygen conservation device. 14 female, 67.9 years (±7.8); FEV1: 27.3%pred. (±8.4); PaO2 at rest without oxygen: 50.3mmHg (±5.9). For both systems, 24/25 patients (96%) were successfully recruited. The mean operating-level difference when success criteria were met was -0.58 in favor of the constant bolus device (95% CI: -0.88 to -0.28, P <0.001). Secondary endpoints (walking distance, respiratory rate and BORG dyspnea) showed no statistically significant or clinically relevant differences. An algorithm created especially for this study showed a high success rate in terms of titration for the required operating level.

Conclusion

Both portable oxygen-conserving devices met the success criteria in 96% of patients in the 6MWT when they were titrated to the correct level. The constant-bolus device required a significantly lower operating level to achieve the success criteria, hereby reducing energy consumption. Individual titration of the respective device is recommended, which can be facilitated by the novel titration algorithm described here.

TRPC6 inhibitor (BI 764198) to reduce risk and severity of ARDS due to COVID-19: a phase II randomised controlled trial

BACKGROUND

Despite the availability of COVID-19 vaccinations, there remains a need to investigate treatments to reduce the risk or severity of potentially fatal complications of COVID-19, such as acute respiratory distress syndrome (ARDS). This study evaluated the efficacy and safety of the transient receptor potential channel C6 (TRPC6) inhibitor, BI 764198, in reducing the risk and/or severity of ARDS in patients hospitalised for COVID-19 and requiring non-invasive, supplemental oxygen support (oxygen by mask or nasal prongs, oxygen by non-invasive ventilation or high-flow nasal oxygen).

METHODS

Multicentre, double-blind, randomised phase II trial comparing once-daily oral BI 764198 (n=65) with placebo (n=64) for 28 days (+2-month follow-up).

PRIMARY ENDPOINT

proportion of patients alive and free of mechanical ventilation at day 29. Secondary endpoints: proportion of patients alive and discharged without oxygen (day 29); occurrence of either in-hospital mortality, intensive care unit admission or mechanical ventilation (day 29); time to first response (clinical improvement/recovery); ventilator-free days (day 29); and mortality (days 15, 29, 60 and 90).

RESULTS

No difference was observed for the primary endpoint: BI 764198 (83.1%) versus placebo (87.5%) (estimated risk difference -5.39%; 95% CI -16.08 to 5.30; p=0.323). For secondary endpoints, a longer time to first response (rate ratio 0.67; 95% CI 0.46 to 0.99; p=0.045) and longer hospitalisation (+3.41 days; 95% CI 0.49 to 6.34; p=0.023) for BI 764198 versus placebo was observed; no other significant differences were observed. On-treatment adverse events were similar between trial arms and more fatal events were reported for BI 764198 (n=7) versus placebo (n=2). Treatment was stopped early based on an interim observation of a lack of efficacy and an imbalance of fatal events (Data Monitoring Committee recommendation).

CONCLUSIONS

TRPC6 inhibition was not effective in reducing the risk and/or severity of ARDS in patients with COVID-19 requiring non-invasive, supplemental oxygen support.

TRIAL REGISTRATION NUMBER

NCT04604184.

Automatic oxygen titration versus constant oxygen flow rates during walking in COPD: a randomised controlled, double-blind, crossover trial

RATIONALE

In patients with COPD, oxygen (O₂)-supplementation via a constant flow oxygen system (CFOS) can result in insufficient oxygen saturation (SpO₂ <90%) during exercise. An automatically titrating O₂-system (ATOS) has been shown to be beneficial compared with an untitrated CFOS, however, it is unknown if ATOS is superior to CFOS, titrated during exercise as stipulated by guidelines. The aim was to investigate the effects of ATOS compared with titrated CFOS on walking capacity in people with hypoxaemic COPD.

METHODS

Fifty participants completed this prospective randomised controlled, double-blind, crossover trial. Participants performed two endurance shuttle walk tests (ESWTs) with: (1) exercise titrated CFOS (ESWT_CFOS) and (2) ATOS targeting an SpO₂ of 92% (ESWT_ATOS). Primary outcome measure was walking time. Secondary measures were SpO₂, transcutaneous-PCO₂ (TcPCO₂), respiratory rate (RR), heart rate (HR) at isotime (end of shortest ESWT) with blood gases and dyspnoea at rest and end exercise.

RESULTS

Participants (median (IQR): age 66 (59, 70) years, FEV₁ 28.8 (24.8, 35.1) % predicted, PO₂ 54.7 (51.0, 57.7) mm Hg, PCO₂ 44.2 (38.2, 47.8) mm Hg) walked significantly longer with ESWT_ATOS in comparison to ESWT_CFOS (median effect (95% CI) +144.5 (54 to 241.5) s, p<0.001). At isotime, SpO₂ was significantly higher (+3 (95% CI 1 to 4) %, p<0.001) with ATOS while TcPCO₂, RR and HR were comparable. End exercise, PO₂ (+8.85 (95% CI 6.35 to 11.9) mm Hg) and dyspnoea (-0.5 (95% CI -1.0 to -0.5) points) differed significantly in favour of ATOS (each p<0.001) while PCO₂ was comparable.

CONCLUSION

In patients with hypoxaemia with severe COPD the use of ATOS leads to significant, clinically relevant improvements in walking endurance time, SpO₂, PO₂ and dyspnoea with no impact on PCO₂.

TRIAL REGISTRATION NUMBER

NCT03803384.

Multidisciplinary Care and Prognosis in Patients With COPD and Interstitial Lung Disease Prescribed Long-Term Oxygen Therapy

BACKGROUND

Home oxygen therapy is prescribed for patients with advanced lung disease based on the criteria established in landmark trials in subjects with COPD. In clinical practice, its use has been extrapolated to other diseases, including interstitial lung disease (ILD). Patients with COPD and ILD experience a high symptom burden and require access to specialized multidisciplinary care. We aimed to evaluate the health-related outcomes and supportive care needs of patients with COPD and ILD receiving home oxygen therapy.

METHODS

This was a retrospective cohort study using the oxygen database of a quaternary metropolitan teaching hospital. Patients with a diagnosis of COPD or ILD who were prescribed home oxygen therapy between January 2012-December 2018 were identified. Demographic information, results of physiologic testing, comorbidities, hospitalizations, and mortality data were collected.

RESULTS

Three hundred and eighty-four subjects were included for analysis, of whom 56% were male. The median age was 75 y. The majority (59%) had a diagnosis of COPD. Long-term oxygen therapy (LTOT) was prescribed for 187 (48.7%), with no significant demographic differences between those with COPD or ILD. Another 187 were prescribed ambulatory oxygen alone, with 55 transitioning to LTOT during the study period. Most subjects (65.4%) were referred for pulmonary rehabilitation; however, palliative care referrals were generally low (22.9%). Referrals to other medical specialties and allied health were common (82%). Transplant-free survival after commencement of LTOT was poor, with 38% of subjects surviving at 5 y. The 5-y survival of subjects with ILD after commencing on LTOT was 10% compared to 52% for those with COPD. Multivariable Cox regression analyses showed that the only predictor of survival after commencing LTOT was the principal respiratory diagnosis.

CONCLUSIONS

This study found that subjects prescribed LTOT had poor transplant-free survival after initiation, which was significantly worse for those with ILD compared to those with COPD. Despite their poor overall survival, worse than many cancers, only a minority were referred for palliative care input. Referrals to pulmonary rehabilitation were also suboptimal. This patient population had complex care needs requiring multidisciplinary management. Appropriate and early referrals to palliative care and improved care coordination for this complex group of patients are key areas for improvement in clinical practice.

Online Patient Information on Domiciliary Oxygen Therapy: An Evaluation of Quality, Suitability, Reliability, Readability and Content

BACKGROUND

Domiciliary oxygen therapy (DOT) is a complex intervention and has significant impact on patients' daily activities, quality of life, and mental wellbeing. Suitable education is pertinent in improving patients' understanding and usage of DOT, as those receiving appropriate education have a better knowledge of their prescription, clearer expectations, and improved adherence to DOT.

RESEARCH QUESTION

Do currently available online patient resources on DOT provide high-quality information for patients?

STUDY DESIGN AND METHODS

We evaluated the first 100 results of three major search engines [Google, Yahoo and Bing] using the terms, "home oxygen therapy" and "information or education". Website content was assessed based on Thoracic Society of Australia and New Zealand and British Thoracic Society domiciliary oxygen guidelines. Validated tools were used to evaluate resource quality [DISCERN instrument], suitability [Suitability Assessment of Materials (SAM)], reliability [Journal of the American Medical Association (JAMA) benchmarks and the Health on the Net (HON) code], and readability [Flesch Reading Ease and Flesch-Kincaid Grade Level].

RESULTS

Thirty-six websites met study inclusion criteria. Websites from foundation/advocacy organisations scored the highest in quality and suitability, with a median DISCERN total score of 48.0 (interquartile range: 43.5-60.0) or "fair" and a median SAM suitability score of 70% (53.0-71.0) or "superior". Industry/for-profit websites had the best content score of 7.8 (5.0-8.6). The HON accreditation seal was present on 14% of the websites and only five websites met the four JAMA benchmarks. The median readability scores exceeded the recommended reading grades of 6th to 8th level for consumer health-related educational resources.

INTERPRETATION

The overall quality, suitability, reliability, and content of online health resources for DOT are of a low-to-moderate standard, with the reading grade at an unsuitable level for the general population. Health professionals should be aware of the limitations of currently available online DOT patient resources.

In vitro evaluation of disposable transport ventilators with combination aerosol therapy

Background

The COVID-19 pandemic has highlighted the need for alternative short-term, reliable means to aid in the treatment of patients requiring ventilatory support. Concurrent aerosol drug delivery is often prescribed to such patients. As such, this study examines one such short-term option, the disposable gas-powered transport ventilator to effectively deliver aerosol therapy. Factors such as aerosol generator type, patient breathing pattern, humidification and nebuliser position within the respiratory circuit were also examined.

Methods

Aerosol drug delivery characterisation was undertaken using two different disposable transport ventilators (DTVs). Two different nebuliser types, a closed circuit vibrating mesh nebuliser (VMN) and an open circuit jet nebuliser (JN), at different locations in a respiratory circuit, proximal and distal to an endotracheal tube (ETT), with and without passive humidification, were evaluated in simulated adult and paediatric patients.

Results

Placement of a nebuliser proximal to the ETT (VMN: 25.19%–34.15% and JN: 3.14%–8.92%), and the addition of a heat and moisture exchange filter (VMN: 32.37%–40.43% and JN: 5.60%–9.91%) resulted in the largest potential lung dose in the adult patient model. Irrespective of nebuliser position and humidification in the respiratory circuit, use of the VMN resulted in the largest potential lung dose (%). A similar trend was recorded in the paediatric model data, where the largest potential lung dose was recorded with both nebuliser types placed proximal to the ETT (VMN: 8.12%–10.89% and JN: 2.15%–3.82%). However, the addition of a heat and moisture exchange filter had no statistically significant effect on the potential lung dose (%) a paediatric patient would receive (p>>0.05).

Conclusions

This study demonstrates that transport ventilators, such as DTVs, can be used concurrently with aerosol generators to effectively deliver aerosolised medication in both adult and paediatric patients.

Automated O2 titration improves exercise capacity in patients with hypercapnic chronic obstructive pulmonary disease: a randomised controlled cross-over trial

Automatically titrated O₂ flows (FreeO₂) was compared with constant O₂ flow on exercise capacity, O₂ saturation and risk of hyperoxia-related hypercapnia in patients with severe COPD with baseline hypercapnia and long-term oxygen therapy (LTOT). Twelve patients were enrolled in a randomised double-blind cross-over study to perform exercise with either FreeO₂ or constant flow. Endurance time (primary outcome) and SpO₂ were both significantly improved with FreeO₂compared with constant flow (p<0.04), although pCO₂ was similar in both conditions. Automated titration of O₂ significantly and clinically improved endurance walking time in patients with severe COPD receiving LTOT, without worsening of pCO₂ TRIAL REGISTRATION NUMBER: Results , NCT01575327.

Comorbidities, Complications and Non-Pharmacologic Treatment in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and fatal disease. The treatment is challenging and nowadays a comprehensive approach based not only in pharmacological strategies is necessary. Identification and control of comorbidities, non-pharmacological treatment, prevention and management of exacerbations as well as other areas of care (social, psychological) are fundamental for a holistic management of IPF. Gastroesophageal reflux, pulmonary hypertension, obstructive sleep apnea, combined with emphysema, lung cancer and cardiovascular involvement are the main comorbidities associated with IPF. Non-pharmacological treatment includes the use of oxygen in patients with rest or nocturnal hypoxemia and other support therapies such as non-invasive ventilation or even a high-flow nasal cannula to improve dyspnea. In some patients, lung transplant should be considered as this enhances survival. Pulmonary rehabilitation can add benefits in outcomes such control of dyspnea, exercise capacity distance and, overall, improve the quality of life; therefore it should be considered in patients with IPF. Also, multidisciplinary palliative care programs could help with symptom control and psychological support, with the aim of maintaining quality of life during the whole process of the disease. This review intends to provide clear information to help those involved in IPF follow up to improve patients’ daily care.

Evaluation by various methods of the physiological mechanism of a high-flow nasal cannula (HFNC) in healthy volunteers

INTRODUCTION

Several reports have described the usefulness of a high-flow nasal cannula (HFNC). However, the physiological mechanisms of this system are unclear. In the current study, various methods were used to investigate the physiological mechanisms of an HFNC in healthy volunteers.

METHODS

The physiological mechanisms of the constant-flow and constant-pressure models of HFNC were studied in 10 healthy volunteers by the oesophageal balloon method, the electrical impedance method and the forced oscillation technique (FOT).

RESULTS

The tidal volume (TV) increased markedly during HFNC (off, 30 L/min, 50 L/min: 685.6±236.5 mL, 929.8±434.7 mL, 968.8±451.1 mL). The end-inspiratory oesophageal pressure (EIOP) was not significantly different, but there was a tendency for it to decrease. HFNC 30 L/min and 50 L/min, the increment in TV and the difference in EIOP showed strong negative correlations (p=0.0025, 0.003). The end-expiratory oesophageal pressure (EEOP) increased. The respiratory system reactance at 5 Hz (X5) by FOT decreased significantly. There was a flow rate-dependent EEOP increase, and the positive end-expiratory pressure (PEEP) effect of HFNC was confirmed. There was a correlation between the difference in X5 and the difference in EEOP during HFNC 30 L/min and 50 L/min, with correlation coefficients of 0.534 and 0.404 (p=0.112, 0.281). The amount of change in EEOP and the fluctuation in X5 were positively correlated.

CONCLUSIONS

The PEEP effect of HFNC was confirmed by the electrical impedance method and FOT. The increment in TV and the difference in EIOP of HFNC showed strong negative correlations.

Bench Evaluation of Four Portable Oxygen Concentrators Under Different Conditions Representing Altitudes of 2438, 4200, and 8000 m

Bunel, Vincent, Amr Shoukri, Frederic Choin, Serge Roblin, Cindy Smith, Thomas Similowski, Capucine Morélot-Panzini, and Jésus Gonzalez. Bench evaluation of four portable oxygen concentrators under different conditions representing altitudes of 2438, 4200, and 8000 m. High Alt Med Biol. 17:370-374, 2016.-Air travel is responsible for a reduction of the partial pressure of oxygen (O₂) as a result of the decreased barometric pressure. This hypobaric hypoxia can be dangerous for passengers with respiratory diseases, requiring initiation or intensification of oxygen therapy during the flight. In-flight oxygen therapy can be provided by portable oxygen concentrators, which are less expensive and more practical than oxygen cylinders, but no study has evaluated their capacity to concentrate oxygen under simulated flight conditions. We tested four portable oxygen concentrators during a bench test study. The O₂ concentrations (FO₂) produced were measured under three different conditions: in room air at sea level, under hypoxia due to a reduction of the partial pressure of O₂ (normobaric hypoxia, which can be performed routinely), and under hypoxia due to a reduction of atmospheric pressure (hypobaric hypoxia, using a chamber manufactured by Airbus Defence and Space). The FO₂ obtained under conditions of hypobaric hypoxia (chamber) was lower than that measured in room air (0.92 [0.89-0.92] vs. 0.93 [0.92-0.94], p = 0.029), but only one portable oxygen concentrator was unable to maintain an FO₂ ≥ 0.90 (0.89 [0.89-0.89]). In contrast, under conditions of normobaric hypoxia (tent) simulating an altitude of 2438 m, none of the apparatuses tested was able to achieve an FO₂ greater than 0.76. (0.75 [0.75-0.76] vs. 0.93 [0.92-0.94], p = 0.029). Almost all portable oxygen concentrators were able to generate a sufficient quantity of O₂ at simulated altitudes of 2438 m and can therefore be used in the aircraft cabin. Unfortunately, verification of the reliability and efficacy of these devices in a patient would require a nonroutinely available technology, and no preflight test can currently be performed by using simple techniques such as hypobaric hypoxia.