Supplemental oxygen improves exercise capacity in IPF patients with exertional desaturation

Enhancing exercise tolerance in interstitial lung disease with high-flow nasal cannula oxygen therapy: A randomized crossover trial

BACKGROUND AND OBJECTIVE

Interstitial lung disease (ILD) is characterized by dyspnoea on exertion and exercise-induced hypoxaemia. High-flow nasal cannula (HFNC) therapy reduces the respiratory workload through higher gas flow and oxygen supplementation, which may affect exercise tolerance. This study aimed to examine the effects of oxygen and gas flow rates through HFNC therapy on exercise tolerance in ILD patients.

METHODS

We conducted three-treatment crossover study. All ILD patients performed the exercises on room air (ROOM AIR setting: flow, 0 L/min; fraction of inspired oxygen [FiO2], 0.21), HFNC (FLOW setting: flow 40 L/min, FiO2 0.21), and HFNC with oxygen supplementation (FLOW + OXYGEN setting: flow 40 L/min, FiO2 0.6). The primary endpoint was the endurance time, measured using constant-load cycle ergometry exercise testing at a peak work rate of 80%.

RESULTS

Twenty-five participants (10 men, 71.2 ± 6.7 years) were enrolled. The increase in exercise duration between the ROOM AIR and FLOW was 46.3 s (95% CI, -6.1 to 98.7; p = 0.083), and the FLOW and FLOW + OXYGEN was 91.5 s (39.1-143.9; p < 0.001). The percutaneous oxygen saturation (SpO2) at rest was significantly higher with the FLOW + OXYGEN setting than with the ROOM AIR and FLOW settings, and the difference persisted during exercise. At equivalent time points during exercise, the SpO2 with the FLOW setting was significantly higher than that with the ROOM AIR setting.

CONCLUSION

Oxygen supplementation in HFNC therapy improved exercise tolerance and SpO2. We found that gas flow alone did not improve exercise tolerance, but improved SpO2 during exercise.

Oxygen therapy for exercise capacity in fibrotic interstitial lung disease: A systematic review and meta-analysis of randomised controlled trials

BACKGROUND

Fibrotic interstitial lung disease (fILD) is characterised primarily by impaired lung function and quality of life. The present study investigated whether oxygen therapy could improve exercise capacity among patients with fILD.

METHODS

Previously published randomised controlled trials (RCTs) were surveyed. A systematic review and meta-analysis was conducted to evaluate the effectiveness of oxygen therapy in improving the exertional capacity of patients with fILD. The primary outcome was peripheral oxygen saturation (SpO2) during exercise. The effects of oxygen therapy on fatigue, dyspnoea, heart rate, and exercise duration or distance were also analysed.

RESULTS

Fourteen RCTs involving 370 patients were included. Oxygen therapy improved SpO2 during exercise (mean difference, MD = 6.26 %), exercise duration (MD = 122.15 s), fatigue (standard mean difference, SMD = -0.30), and dyspnoea (MD = -0.75 Borg score units). High-flow oxygen systems tended to be more effective than low-flow systems in improving exercising SpO2, duration, fatigue, dyspnoea, and heart rate. High-flow nasal cannulas (HFNCs) yielded better outcomes regarding SpO2 and fatigue than did high-flow Venturi masks (MD = 1.60 % and MD = -1.19 Borg score units, respectively). No major adverse events were reported.

CONCLUSION

The evidence from RCTs supports the short-term use of oxygen supplementation to improve SpO2, exercise capacity, fatigue, and dyspnoea among patients with fILD. Further analyses demonstrates that HFNCs yield more favourable outcomes, yet not reaching statistical significance except for improving SpO2 and fatigue. However, the long-term effects of oxygen therapy on quality of life and mortality remain unclear.

Predicting New-onset Exertional and Resting Hypoxemia in Fibrotic Interstitial Lung Disease

Rationale: Hypoxemia in fibrotic interstitial lung disease (ILD) indicates disease progression and is of prognostic significance. The onset of hypoxemia signifies disease progression and predicts mortality in fibrotic ILD. Accurately predicting new-onset exertional and resting hypoxemia prompts appropriate patient discussion and timely consideration of home oxygen. Objectives: We derived and externally validated a risk prediction tool for both new-onset exertional and new-onset resting hypoxemia. Methods: This study used ILD registries from Canada for the derivation cohort and from Australia and the United States for the validation cohort. New-onset exertional and resting hypoxemia were defined as nadir oxyhemoglobin saturation < 88% during 6-minute-walk tests, resting oxyhemoglobin saturation < 88%, or the initiation of ambulatory or continuous oxygen. Candidate predictors included patient demographics, ILD subtypes, and pulmonary function. Time-varying Cox regression was used to identify the top-performing prediction model according to Akaike information criterion and clinical usability. Model performance was assessed using Harrell's C-index and goodness-of-fit (GoF) likelihood ratio test. A categorized risk prediction tool was developed. Results: The best-performing prediction model for both new-onset exertional and new-onset resting hypoxemia included age, body mass index, a diagnosis of idiopathic pulmonary fibrosis, and percent predicted forced vital capacity and diffusing capacity of carbon monoxide. The risk prediction tool exhibited good performance for exertional hypoxemia (C-index, 0.70; GoF, P = 0.85) and resting hypoxemia (C-index, 0.77; GoF, P = 0.27) in the derivation cohort, with similar performance in the validation cohort except calibration for resting hypoxemia (GoF, P = 0.001). Conclusions: This clinically applicable risk prediction tool predicted new-onset exertional and resting hypoxemia at 6 months in the derivation cohort and a diverse validation cohort. Suboptimal GoF in the validation cohort likely reflected overestimation of hypoxemia risk and indicated that the model is not flawed because of underestimation of hypoxemia.

Supplemental Oxygen Therapy in Interstitial Lung Disease: A Narrative Review

Patients with interstitial lung diseases (ILD) often have hypoxemia at rest and/or with exertion, for which supplemental oxygen is commonly prescribed. The number of patients with ILD who require supplemental oxygen is unknown, although estimates suggest it could be as much as 40%; many of these patients may require high-flow support (>4 L/min). Despite its frequent use, there is limited evidence for the impact of supplemental oxygen on clinical outcomes in ILD, with recommendations for its use primarily based on older studies in patients with chronic obstructive pulmonary disease. Oxygen use in ILD is rarely included as an outcome in clinical trials. Available evidence suggests that supplemental oxygen in ILD may improve quality of life and some exercise parameters in patients whose hypoxemia is a limiting factor; however, oxygen therapy also places new burdens and barriers on some patients that may counter its beneficial effects. The cost of supplemental oxygen in ILD is also unknown but likely represents a significant portion of overall healthcare costs in these patients. Current Centers for Medicare and Medicaid reimbursement policies provide only a modest increase in payment for high oxygen flows, which may negatively impact access to oxygen services and equipment for some patients with ILD. Future studies should examine clinical and quality-of-life outcomes for oxygen use in ILD. In the meantime, given the current limited evidence for supplemental oxygen and considering cost factors and other barriers, providers should take a patient-focused approach when considering supplemental oxygen prescriptions in patients with ILD.

A retrospective study of crossover ambulatory oxygen walk testing in patients with fibrotic lung disease

BACKGROUND

Fibrotic interstitial lung disease (ILD) comprises a group of lung conditions that are often progressive, debilitating, and life-shortening. Ambulatory oxygen therapy (AOT) is regularly prescribed to manage symptoms in patients with fibrotic ILD. In our institution, the decision to prescribe portable oxygen is made on the basis of oxygen improving exercise capacity, measured with the single-blinded, crossover ambulatory oxygen walk test (AOWT). This study aimed to investigate the characteristics and survival rates of patients with fibrotic ILD who have either positive or negative results on the AOWT.

METHODS

This retrospective cohort study compared the data from 99 patients with fibrotic ILD who underwent the AOWT. These patients were classified into two groups based on whether they showed improvement in the AOWT with supplemental oxygen (positive group) or no improvement (negative group). Patient demographics for both groups were compared to determine any significant differences. A multivariate Cox proportional hazards model was used to analyze the survival rates of the two groups.

RESULTS

Out of the 99 patients, 71 were in the positive group. We compared the measured characteristics between the positive and negative groups and found no significant difference, wherein the adjusted hazard ratio was 1.33 (95% confidence interval 0.69-2.60, P = 0.40).

CONCLUSIONS

The AOWT can be used to rationalize AOT, but there was no significant difference in baseline characteristics or survival rates between patients whose performance was improved or not in the AOWT.

Oxygen in interstitial lung diseases

Domiciliary oxygen is essential in the care of hypoxaemic interstitial lung disease (ILD) patients. Guidelines concur in advising prescription of long-term oxygen therapy (LTOT) for ILD patients with severe hypoxaemia at rest, in view of its beneficial impact on breathlessness/disability and extrapolating potential survival benefits seen in COPD patients. A less severe hypoxaemia threshold for initiation of LTOT is recommended for patients with pulmonary hypertension (PH)/right heart failure, requiring careful evaluation in all ILD patients. In light of evidence suggesting a link between nocturnal hypoxaemia, development of PH and poor survival, studies assessing the impact of nocturnal oxygen are urgently needed. Severe exertional hypoxaemia is frequent in ILD patients, with impact on exercise tolerance, quality of life and mortality. Ambulatory oxygen therapy (AOT) has been associated with improvement in breathlessness and quality of life in ILD patients with exertional hypoxaemia. However, given the paucity of evidence, not all current AOT guidelines are in agreement. Ongoing clinical trials will provide further useful data. Despite its beneficial effects, supplemental oxygen imposes burdens and challenges to patients. A key unmet area of need is the development of less cumbersome and more efficient oxygen delivery systems to reduce the negative impact of AOT on patients' lives.

2022 Brazilian Thoracic Association recommendations for long-term home oxygen therapy

Some chronic respiratory diseases can cause hypoxemia and, in such cases, long-term home oxygen therapy (LTOT) is indicated as a treatment option primarily to improve patient quality of life and life expectancy. Home oxygen has been used for more than 70 years, and support for LTOT is based on two studies from the 1980s that demonstrated that oxygen use improves survival in patients with COPD. There is evidence that LTOT has other beneficial effects such as improved cognitive function, improved exercise capacity, and reduced hospitalizations. LTOT is indicated in other respiratory diseases that cause hypoxemia, on the basis of the same criteria as those used for COPD. There has been an increase in the use of LTOT, probably because of increased life expectancy and a higher prevalence of chronic respiratory diseases, as well as greater availability of LTOT in the health care system. The first Brazilian Thoracic Association consensus statement on LTOT was published in 2000. Twenty-two years la-ter, we present this updated version. This document is a nonsystematic review of the literature, conducted by pulmonologists who evaluated scientific evidence and international guidelines on LTOT in the various diseases that cause hypoxemia and in specific situations (i.e., exercise, sleep, and air travel). These recommendations, produced with a view to clinical practice, contain several charts with information on indications for LTOT, oxygen sources, accessories, strategies for improved efficiency and effectiveness, and recommendations for the safe use of LTOT, as well as a LTOT prescribing model.

[French practical guidelines for the diagnosis and management of IPF - 2021 update, full version]

BACKGROUND

Since the previous French guidelines were published in 2017, substantial additional knowledge about idiopathic pulmonary fibrosis has accumulated.

METHODS

Under the auspices of the French-speaking Learned Society of Pulmonology and at the initiative of the coordinating reference center, practical guidelines for treatment of rare pulmonary diseases have been established. They were elaborated by groups of writers, reviewers and coordinators with the help of the OrphaLung network, as well as pulmonologists with varying practice modalities, radiologists, pathologists, a general practitioner, a head nurse, and a patients' association. The method was developed according to rules entitled "Good clinical practice" in the overall framework of the "Guidelines for clinical practice" of the official French health authority (HAS), taking into account the results of an online vote using a Likert scale.

RESULTS

After analysis of the literature, 54 recommendations were formulated, improved, and validated by the working groups. The recommendations covered a wide-ranging aspects of the disease and its treatment: epidemiology, diagnostic modalities, quality criteria and interpretation of chest CT, indication and modalities of lung biopsy, etiologic workup, approach to familial disease entailing indications and modalities of genetic testing, evaluation of possible functional impairments and prognosis, indications for and use of antifibrotic therapy, lung transplantation, symptom management, comorbidities and complications, treatment of chronic respiratory failure, diagnosis and management of acute exacerbations of fibrosis.

CONCLUSION

These evidence-based guidelines are aimed at guiding the diagnosis and the management in clinical practice of idiopathic pulmonary fibrosis.

The Association between Idiopathic Pulmonary Fibrosis and Obstructive Sleep Apnea: A Systematic Review and Meta-Analysis

The prevalence of obstructive sleep apnea (OSA) has greatly increased in recent years. Recent data suggest that severe and moderate forms of OSA affect between 6 and 17% of adults in the general population. Many papers are reporting the significantly increased prevalence of OSA in patients suffering from fibrotic diseases, including idiopathic pulmonary fibrosis (IPF). Therefore, we performed a systematic review and meta-analysis regarding the dependency between IPF and OSA. Due to the lack of papers focusing on IPF among OSA patients, we focused on the prevalence of OSA among IPF patients. In the search strategy, a total of 684 abstracts were identified, 496 after the removal of duplicates. After the screening of titles and abstracts, 31 studies were qualified for further full-text analysis for eligibility criteria. The final analysis was performed on 614 IPF patients from 18 studies, which met inclusion criteria. There were 469 (76.38%) IPF patients with OSA and 145 (23.62%) without. The mean age varied from 60.9 ± 8.1 up to 70.3 ± 7.9. The obtained prevalence was 76.4 (95% CI: 72.9–79.7) and 75.7 (95% CI: 70.1–80.9) for fixed and random effects, respectively. The median prevalence of OSA among non-IPF patients for all the ethnics groups included in this study was 16,4% (IQR: 3.4%–26.8%). The study provides strong evidence for the increased prevalence of OSA in IPF patients when comparing with the general OSA prevalence.

French practical guidelines for the diagnosis and management of idiopathic pulmonary fibrosis - 2021 update. Full-length version

BACKGROUND

Since the latest 2017 French guidelines, knowledge about idiopathic pulmonary fibrosis has evolved considerably.

METHODS

Practical guidelines were drafted on the initiative of the Coordinating Reference Center for Rare Pulmonary Diseases, led by the French Language Pulmonology Society (SPLF), by a coordinating group, a writing group, and a review group, with the involvement of the entire OrphaLung network, pulmonologists practicing in various settings, radiologists, pathologists, a general practitioner, a health manager, and a patient association. The method followed the "Clinical Practice Guidelines" process of the French National Authority for Health (HAS), including an online vote using a Likert scale.

RESULTS

After a literature review, 54 guidelines were formulated, improved, and then validated by the working groups. These guidelines addressed multiple aspects of the disease: epidemiology, diagnostic procedures, quality criteria and interpretation of chest CT scans, lung biopsy indication and procedures, etiological workup, methods and indications for family screening and genetic testing, assessment of the functional impairment and prognosis, indication and use of antifibrotic agents, lung transplantation, management of symptoms, comorbidities and complications, treatment of chronic respiratory failure, diagnosis and management of acute exacerbations of fibrosis.

CONCLUSION

These evidence-based guidelines are intended to guide the diagnosis and practical management of idiopathic pulmonary fibrosis.

Exercise Tolerance in Patients With Idiopathic Pulmonary Fibrosis, Effect of Supplemental Oxygen

Exercise tolerance in patients with idiopathic pulmonary fibrosis IPF is mainly limited by mechanical constrain of ventilation and high physiologic dead space. Oxygen enriched gas inhalation seems to increase ventilatory efficiency by reduction of dead space to tidal volume ratio (VD/VT) which probably mirrors improved pulmonary capillary flow and leads to longer physical tolerance at lower level of minute ventilation. The effect is noticeable at FIO2 that can be delivered in rehabilitation purposes or daily living activities.

[French practical guidelines for the diagnosis and management of IPF - 2021 update, short version]

BACKGROUND

Since the previous French guidelines were published in 2017, substantial additional knowledge about idiopathic pulmonary fibrosis has accumulated.

METHODS

Under the auspices of the French-speaking Learned Society of Pulmonology and at the initiative of the coordinating reference center, practical guidelines for treatment of rare pulmonary diseases have been established. They were elaborated by groups of writers, reviewers and coordinators with the help of the OrphaLung network, as well as pulmonologists with varying practice modalities, radiologists, pathologists, a general practitioner, a head nurse, and a patients' association. The method was developed according to rules entitled "Good clinical practice" in the overall framework of the "Guidelines for clinical practice" of the official French health authority (HAS), taking into account the results of an online vote using a Likert scale.

RESULTS

After analysis of the literature, 54 recommendations were formulated, improved, and validated by the working groups. The recommendations covered a wide-ranging aspects of the disease and its treatment: epidemiology, diagnostic modalities, quality criteria and interpretation of chest CT, indication and modalities of lung biopsy, etiologic workup, approach to familial disease entailing indications and modalities of genetic testing, evaluation of possible functional impairments and prognosis, indications for and use of antifibrotic therapy, lung transplantation, symptom management, comorbidities and complications, treatment of chronic respiratory failure, diagnosis and management of acute exacerbations of fibrosis.

CONCLUSION

These evidence-based guidelines are aimed at guiding the diagnosis and the management in clinical practice of idiopathic pulmonary fibrosis.

Impact of high-flow oxygen therapy during exercise in idiopathic pulmonary fibrosis: a pilot crossover clinical trial

BACKGROUND

Supplemental oxygen delivered with standard oxygen therapy (SOT) improves exercise capacity in patients with idiopathic pulmonary fibrosis (IPF). Although high-flow nasal cannula oxygen therapy (HFNC) improves oxygenation in other respiratory diseases, its impact on exercise performance has never been evaluated in IPF patients. We hypothesized that HFNC may improve exercise capacity in IPF subjects compared to SOT.

METHODS

This was a prospective, crossover, pilot randomized trial that compared both oxygenation methods during a constant submaximal cardiopulmonary exercise test (CPET) in IPF patients with exertional oxygen saturation (SpO₂) ≤ 85% in the 6-min walking test. The primary outcome was endurance time (Tlim). Secondary outcomes were muscle oxygen saturation (StO₂) and respiratory and leg symptoms.

RESULTS

Ten IPF patients [71.7 (6) years old, 90% males] were included. FVC and DL_CO were 58 ± 11% and 31 ± 13% pred. respectively. Tlim during CPET was significantly greater using HFNC compared to SOT [494 ± 173 vs. 381 ± 137 s, p = 0.01]. HFNC also associated with a higher increase in inspiratory capacity (IC) [19.4 ± 14.2 vs. 7.1 ± 8.9%, respectively; p = 0.04], and a similar trend was observed in StO₂ during exercise. No differences were found in respiratory or leg symptoms between the two oxygen devices.

CONCLUSIONS

This is the first study demonstrating that HFNC oxygen therapy improves exercise tolerance better than SOT in IPF patients with exertional desaturation. This might be explained by changes in ventilatory mechanics and muscle oxygenation. Further and larger studies are needed to confirm the benefits of HFNC in IPF patients and its potential usefulness in rehabilitation programs.

Telemonitoring of daily activities compared to the six-minute walk test further completes the puzzle of oximetry-guided interventions

Pulmonary rehabilitation is based on a thorough patient assessment, including peripheral oxygen saturation (SpO₂) and heart rate (HR) at rest and on exertion. To understand whether exercise-field tests identify patients who desaturate (SpO₂ < 90%) during physical activities, this study compared the six-minute walk test (6MWT) and daily-life telemonitoring. Cross-sectional study including 100 patients referred for pulmonary rehabilitation. The 6MWT was performed in hospital with continuous assessment of SpO₂, HR, walked distance and calculated metabolic equivalent of tasks (METs). Patients were also evaluated in real-life by SMARTREAB telemonitoring, a combined oximetry-accelerometery with remote continuous assessment of SpO₂, HR and METs. SMARTREAB telemonitoring identified 24% more desaturators compared with the 6MWT. Moreover, there were significant mean differences between 6MWT and SMARTREAB in lowest SpO₂ of 7.2 ± 8.4% (P < 0.0005), in peak HR of - 9.3 ± 15.5% (P < 0.0005) and also in activity intensity of - 0.3 ± 0.8 METs (P < 0.0005). The 6MWT underestimates the proportion of patients with exercise-induced oxygen desaturation compared to real-life telemonitoring. These results help defining oximetry-guided interventions, such as telemedicine algorithms, oxygen therapy titration and regular physical activity assessment in pulmonary rehabilitation.

Management of Idiopathic Pulmonary Fibrosis

Progress in the past 2 decades has led to widespread use of 2 medications to slow loss of lung function in patients with pulmonary fibrosis. Treatment of individual patients with currently available pharmacotherapies can be limited by side effects, and neither drug has a consistent effect on patient symptoms or function. Several promising new pharmacotherapies are under development. Comprehensive management of pulmonary fibrosis hinges on shared decision making. Patient and caregiver education, and early identification and management of symptoms and comorbidities, can help improve quality of life.

Effects of oxygen supplementation in autonomic nervous system function during exercise in patients with idiopathic pulmonary fibrosis and exertional desaturation

INTRODUCTION

Patients with idiopathic pulmonary fibrosis (IPF) have reduced exercise capacity and often present exertional dyspnea and desaturation. The role of autonomic nervous system (ANS) as a pathogenetic contributor to this dysfunction has not been evaluated.

OBJECTIVE

To evaluate whether improvement of arterial oxygen saturation (SpO₂ ) via oxygen supplementation results to ANS function improvement, during steady state submaximal exercise.

METHODS

This is a secondary analysis of a single-blind, randomized, placebo-controlled, cross-over trial, including 12 IPF patients, with isolated exertional desaturation. Following a maximal cardiopulmonary test, participants underwent two submaximal steady state tests during which they received either supplementary oxygen or medical air. Continuous beat-to-beat blood pressure measurements were recorded (Finapres Medical Systems, Amsterdam, The Netherlands). Autonomic function was assessed non-invasively by heart rate variability (HRV); root mean square of successive differences (RMSSD) and standard-deviation-Poincare-plot (SD1) were used as indices of parasympathetic output. Entropy and detrended fluctuation analysis (DFA) were also used.

RESULTS

During rest, oxygen supplementation did not significantly alter RMSSD and SD1. During exercise, subjects presented no significant alterations compared with baseline, in most HRV indices examined. There was no improvement of this behavior with O₂ -supplementation. Approximate-entropy increased during exercise, with no differences between protocols.

CONCLUSIONS

IPF patients presented an inadequate adaptive response of their ANS to exercise and recovery. Although oxygen supplementation significantly prolonged exercise duration and prevented the substantial exertional desaturation, the blunted vagal response to steady-state exercise in these patients was not improved, suggesting that acute oxygen supplementation does not sufficiently improve ANS dysfunction in these patients.

Contemporary Concise Review 2020: Interstitial lung disease

The year 2020 was one like no other, as we witnessed the far-reaching impact of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) global pandemic. Yet despite an unprecedented and challenging year, global research in interstitial lung disease (ILD) continued to break new grounds. Research progress has led to an improved understanding in new diagnostic tools and potential biomarkers for ILD. Studies on the role of antifibrotic therapies, newer therapeutic agents, supportive care strategies and the impact of coronavirus disease 2019 (COVID-19) continue to reshape the management landscape of ILD. In this concise review, we aim to summarize the key studies published in 2020, highlighting their impact on the various aspects of ILD.

Pulmonary fibrosis secondary to COVID-19: a narrative review

Introduction: Coronavirus disease 2019 (COVID-19) is still increasing worldwide, and as a result, the number of patients with pulmonary fibrosis secondary to COVID-19 will expand over time. Risk factors, histopathological characterization, pathophysiology, prevalence, and management of post-COVID-19 pulmonary fibrosis are poorly understood, and few studies have addressed these issues.Areas covered:This article reviews the current evidence regarding post-COVID-19 pulmonary fibrosis, with an emphasis on the potential risk factors, histopathology, pathophysiology, functional and tomographic features, and potential therapeutic modalities. A search on the issue was performed in the MEDLINE, Embase, and SciELO databases and the Cochrane library between 1 December 2019, and 25 January 2021. Studies were reviewed and relevant topics were incorporated into this narrative review. Expert opinion: Pulmonary sequelae may occur secondary to COVID-19, which needs to be included as a potential etiology in the current differential diagnosis of pulmonary fibrosis. Therefore, serial clinical, tomographic, and functional screening for pulmonary fibrosis is recommended after COVID-19, mainly in patients with pulmonary involvement in the acute phase of the disease. Further studies are necessary to determine the risk factors, markers, pathophysiology, and appropriate management of post-COVID-19 pulmonary fibrosis.

Exertional Desaturation in Idiopathic Pulmonary Fibrosis: The Role of Oxygen Supplementation in Modifying Cerebral-Skeletal Muscle Oxygenation and Systemic Hemodynamics

BACKGROUND

In patients with idiopathic pulmonary fibrosis (IPF) with isolated exertional desaturation, there are limited data regarding the effectiveness of oxygen supplementation during exercise training; the underlying mechanisms that contribute to these responses are unknown.

OBJECTIVES

To examine in these IPF patients the effects of oxygen supplementation during submaximal exercise (vs. medical air) on cerebral/skeletal muscle oxygenation and systemic hemodynamics.

METHODS

In this randomized, cross-over, placebo-controlled trial, IPF patients (n = 13; 63.4 ± 9.6 years) without resting hypoxemia but a significant desaturation during maximal cardiopulmonary exercise testing underwent 2 steady-state exercise trials (65% peak-work-load), breathing either oxygen-enriched or medical air. Cerebral/skeletal muscle oxygenation (near-infrared spectroscopy) and beat-by-beat hemodynamics (photoplethysmography) were monitored.

RESULTS

In the air protocol, from the initial minutes of submaximal exercise, patients exhibited a marked decline in cerebral oxygenated hemoglobin (O2Hb) and an abrupt rise in deoxygenated hemoglobin (HHb). Oxygen supplementation alleviated desaturation, lessened dyspnea, and prolonged exercise duration (p < 0.01). Oxygen supplementation during exercise (i) attenuated cerebral deoxygenation (cerebral-HHb: 0.7 ± 1.9 vs. 2.5 ± 1.5 μmol/L, O2 and air protocol; p = 0.009) and prevented cerebral-Hbdifference decline (2.1 ± 2.7 vs. -1.7 ± 2.0 μmol/L; p = 0.001), (ii) lessened the decline in muscle O2-saturation index, and (iii) at isotime exercise, it resulted in lower muscle-HHb (p = 0.05) and less leg fatigue (p < 0.05). No differences between protocols were observed in exercise cardiac output and vascular resistance.

CONCLUSIONS

IPF patients with isolated exertional hypoxemia exhibit an inability to increase/maintain cerebral oxygenation during submaximal exercise. Correcting desaturation with O2 supplementation prevented the decline in brain oxygenation, improved muscle oxygenation, and lessened dyspnea, suggesting an efficacy of acute oxygen supplementation during exercise training in protecting brain hypoxia in these IPF patients.