Exercise-induced Desaturation Research Articles

The 1-min sit-to-stand test as a screening tool to assess exercise-induced oxygen desaturation in normoxemic people with interstitial lung disease

BackgroundIn patients with interstitial lung disease (ILD), exercise-induced desaturation during the 6-min walk test (6MWT), specifically nadir oxygen saturation (nSpO2) of ≤88 % is a negative prognostic marker. As the 6MWT is often impractical for ILD patients, the aim of this study is to compare the 1-min sit-to-stand test (1minSTS) with the 6MWT to detect exercise-induced desaturation. MethodsParticipants were recruited from a tertiary referral clinic with both tests performed on the same day. Utilising Bland-Altman analysis, the relationship between nSpO2 on 1minSTS and 6MWT was determined. An area under the receiver operating characteristic curve (AUC) determined the ability of nSpO2 on 1minSTS test to predict SpO2 ≤88 % on 6MWT. ResultsFifty participants completed the study (idiopathic pulmonary fibrosis n = 24, 48 %; connective tissue disease associated ILD n = 20, 40 %; other ILD n = 6, 12 %). Mean (SD) FVC%pred was 73 ± 16 %, mean DLCO%pred 57 ± 16 % and resting SpO2 99 ± 1 %. The 1minSTS resulted in less exercise-induced oxygen desaturation, with a median IQR nSpO2 of 95 % (89–98) and 93 % (85–96) respectively (p < 0.001). Moderate agreement was determined between the nSpO2 on both tests, with a mean difference of 3.2 % [-14 to +3.0 %]. The 1minSTS test accurately identified participants with nSpO2 ≤88 % on 6MWT (AUC 0.96). Oxygen desaturation ≤94 % during the 1minSTS test provided 100 % sensitivity and 87 % specificity for oxygen desaturation ≤88 % at 6MWT. ConclusionThis study demonstrates that exercise-induced oxygen desaturation during the 1minSTS test correlates with oxygen desaturation on 6MWT. The 1minSTS may be a practical screening tool for ILD patients who would benefit from further exercise testing.

Pulmonary rehabilitation in idiopathic pulmonary fibrosis.

This review synthesizes the expanding evidence for pulmonary rehabilitation that has led to its recommended inclusion in the holistic care of people with idiopathic pulmonary fibrosis (IPF), as well as discussing strategies that may maximize and sustain benefits. Pulmonary rehabilitation is an effective intervention leading to significant improvements in exercise tolerance, symptoms, and quality of life for people with IPF. Improvements in symptoms and quality of life can persist longer term, whereas functional capacity does not; therefore, strategies to preserve functional capacity are an important area of research. Referral early in the disease course is encouraged to promote longer lasting effects. Evidence that high-intensity interval training may optimize benefits of exercise training is emerging. Supplemental oxygen is frequently used to manage exercise-induced desaturation, although its use as an adjunct therapy requires more evidence. Current evidence strongly supports the inclusion of pulmonary rehabilitation in the standard holistic care of IPF, with early participation encouraged. Further research is needed to establish the optimal exercise strategies, modalities and adjunct therapies that enhance outcomes of pulmonary rehabilitation and promote longer lasting effects.

Symposium review: high altitude travel with pulmonary vascular disease.

Pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension are the main precapillary forms of pulmonary hypertension (PH) summarized as pulmonary vascular diseases (PVD). PVDs are characterized by exertional dyspnoea and oxygen desaturation, and reduced quality of life and survival. Medical therapies improve life expectancy and physical performance of PVD patients, of whom many wish to participate in professional work and recreational activities including traveling to high altitude. The exposure to the hypobaric hypoxic environment of mountain regions incurs the risk of high altitude adverse events (AEHA) due to severe hypoxaemia exacerbating symptoms and further increase in pulmonary artery pressure, which may lead to right heart decompensation. Recent prospective and randomized trials show that altitude-induced hypoxaemia, pulmonary haemodynamic changes and impairment of exercise performance in PVD patients are in the range found in healthy people. The vast majority of optimally treated stable PVD patients who do not require long-term oxygen therapy at low altitude can tolerate short-term exposure to moderate altitudes up to 2500m. PVD patients that reveal persistent severe resting hypoxaemia ( <80% for >30min) at 2500m respond well to supplemental oxygen therapy. Although there are no accurate predictors for AEHA, PVD patients with unfavourable risk profiles at low altitude, such as higher WHO functional class, lower exercise capacity with more pronounced exercise-induced desaturation and more severely impaired haemodynamics, are at increased risk of AEHA. Therefore, doctors with experience in PVD and high-altitude medicine should counsel PVD patients before any high-altitude sojourn. This review aims to summarize recent literature and clinical recommendations about PVD patients travelling to high altitude.

Evaluation of novel indices of walking performance taking oxygen desaturation into account during six-minute walk test in cardiovascular disease patients.

In pulmonary disease patients since oxygen desaturation during 6-min walk test (6MWT) affects walk distance (6MWD), some novel indices such as desaturation/distance ratio [DDR, oxygen desaturation area (DAO2)/6MWD] and distance-saturation product [DSP, 6MWD × minimum peripheral oxygen saturation (SpO2)] are evaluated. However, there has been no study examining these indices that consider exercise-induced desaturation (EID) in patients with cardiovascular disease. In 94 cardiovascular disease patients without pulmonary complications, 6MWT and echocardiography were performed at the entry of cardiac rehabilitation. SpO2 was measured during 6MWT using a continuously monitorable pulse oximeter, and DSP and DDR were calculated using minimum SpO2 and DAO2 [sum of (100-SpO2) per second during 6MWT], respectively. EID was defined as SpO2 decrease of ≥ 4% or minimum SpO2 of < 90% during 6MWT. DSP was slightly lower and DDR was markedly higher in patients with EID than in those without. When examining correlations of DSP and DDR with their components, DSP was correlated with 6MWD much closely than minimum SpO2, while DDR was correlated as closely with DAO2 as 6MWD. Furthermore, DAO2, but not minimum SpO2, had a direct correlation with 6MWD. As for associations with cardiac function, DSP was correlated with several cardiac parameters, but DDR was not correlated with any of these parameters. Our findings suggest that oxygen desaturation during 6MWT affects walking distance in cardiovascular disease patients even without pulmonary complications and that DDR is more appropriate than DSP as an index of walking performance that takes EID into consideration, independently of cardiac function.

Genotypic Variations in Exercise-Induced Hemoglobin Oxygen Desaturation in Sickle Cell Disease: The Role of Hemoglobin Levels

Background: Sickle cell disease (SCD) presents abnormal hemoglobin S (HbS) and frequent vaso-occlusive crises. Previous studies reveal exercise intolerance in SCD patients. However, the role of exercise-induced hemoglobin oxygen desaturation (EIHOD) and its predictors remains unclear. This study investigates EIHOD in adult SCD patients, focusing on potential predictors, aligning with the hypothesis that EIHOD is prevalent and varies across genotypes, with hemoglobin as a predictor. Methods: A cross-sectional study was conducted on adult patients with HbSS and HbSC genotypes in a steady state at the Korle-Bu Teaching Hospital, Ghana. Clinical, hematological, and haemolytic markers were assessed. Lung function was evaluated through spirometry, and a six-minute walk test (6MWT) was performed to assess EIHOD. Logistic regression was used to identify predictors of EIHOD. We hypothesis that, EIHOD is common in SCD, varying across genotypes, with hemoglobin predicting its occurrence. Results: The prevalence of EIHOD was 41% in HbSS patients and 36.1% in HbSC patients. No significant differences were observed in age, white blood cell count, platelet count, hemolytic markers, hemoglobin levels, or lung function parameters between SCD patients with and without EIHOD. In the logistic regression model, none of the variables predicted EIHOD in HbSS patients. In HbSC patients, reduced hemoglobin was the only predictor of EIHOD (OR=0.551; 95% CI=0.315-0.964; p-value= 0.037). Discussion: The study highlights a high prevalence of EIHOD within the HbSS genotype, emphasizing the importance of hemoglobin levels as a predictor of EIHOD in SCD. Contrarily, hemolytic markers and lung function were not predictors of EIHOD across either genotype. These results suggest the potentially heightened significance of EIHOD-related complications in patients with the HbSS genotype. Conclusion: EIHOD is common in SCD, more so in HbSS. Reduced hemoglobin predicts EIHOD in HbSC. Lung function and hemolytic markers don't. Understanding the impact of EIHOD in SCD may guide interventions to improve exercise tolerance and reduce complications in this population. No Funding. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

HLA-G 14-bp variant is associated with exercise-induced oxygen desaturation in the post-COVID-19 condition.

The HLA-G 14-bp indel (rs371194629) variant is associated with IMV requirement in COVID-19 and with exercise-induced desaturation in the post-COVID-19 condition https://bit.ly/3THdx1D.

Prevalence of Exercise-induced Desaturation in Survivors of Severe COVID-19 Pneumonia and the Predictive Value of Lung Ultrasound: A Cross-sectional Study

Introduction: Survivors of severe Coronavirus Disease2019 (COVID-19) pneumonia may experience ExerciseInduced Desaturation (EID), which can remain undiagnosed at discharge, as most exhibit normal resting Arterial Blood Gases (ABGs). This undiagnosed condition may lead to unexpected hospital readmissions, causing additional burden to the health system. However, the prevalence of EID among this population, especially in developing countries, is not well documented. Aim: To estimate the prevalence of EID among survivors of severe COVID-19 pneumonia and to explore the predictive role of Lung Ultrasound Scan (LUS) in detecting EID. Materials and Methods: This hospital-based, observational, cross-sectional study was conducted at the Institute of Chest Diseases in Kozhikode, Kerala, India from October 2021 to September 2022. It involved 153 COVID-19 patients aged 18 years and above who had recovered from severe pneumonia, were otherwise fit for hospital discharge, and had normal resting ABGs. The study examined the prevalence of EID using the 6-Minute Walk Test (6MWT). Additionally, it investigated the predictive ability of a LUS for EID. A LUS was performed on all patients and scoring was conducted according to the established protocol. Results: The mean age of the study subjects was 53.50±14.13 years, with 119 (77.8%) being male. During the 6MWT, 96 patients (62.7%) showed significant desaturation. A total of 83 (95.4%) subjects in the desaturated group required Non-Invasive Ventilation (NIV) compared to 4 (4.6%) in the non-desaturated group (p&lt;0.001). All 24 (100%) subjects in the desaturated group required Invasive Mechanical Ventilation (IMV), while none in the non-desaturated group did. The mean Length Of Stay (LOS) in the hospital was 35.50±13.35 days for the desaturated group, compared to 23.32±16.25 days for the non-desaturated group (p&lt;0.001). The LUS score was significantly higher in the desaturated group (16.61±5.92) than in the non-desaturated group (5.54±4.62). The Receiver Operating Characteristic (ROC) curve for the LUS score indicated a cut-off value of 8.5 for identifying significant EID. Conclusion: Survivors of COVID-19 who recovered from Acute Respiratory Failure (ARF) and have normal resting ABGs may still have significant EID. A protocol-based LUS score can potentially identify individuals at risk for EID.

Exercise-induced desaturation during a six-minute walk test is associated with poor clinical outcomes in patients with pulmonary arterial hypertension

BackgroundThe six-minute walk test (6MWT) is an established exercise test for patients with pulmonary arterial hypertension (PAH), affording insight into both exercise intolerance and overall prognosis. Despite the widespread application of the 6MWT, the prognostic implications of exercise-induced desaturation (EID) during this test has been inadequately studied in PAH patients. Thus, we evaluated the occurrence of EID and its prognostic significance in PAH patients.MethodsWe analyzed PAH patients in a single-center cohort from April 2016 to March 2021. EID was defined as a reduction in oxygen saturation exceeding 4% from the baseline or to below 90% at any point during the test.ResultsWe analyzed 20 PAH patients in this cohort, primarily consisting of 16 females with an average age of 48.4 ± 13.3 years. Among them, ten exhibited EID. Baseline characteristics, echocardiographic data and right heart catheterization data were similar between the two groups. However, total distance (354.3 ± 124.4 m vs. 485.4 ± 41.4 m, P = 0.019) and peak oxygen uptake (12.9 ± 3.2 mL/kg⋅min vs. 16.4 ± 3.6 mL/kg⋅min, P = 0.019) were significantly lower in the EID group. During the total follow-up duration of 51.9 ± 25.7 months, 17 patients had at least one adverse clinical event (2 deaths, 1 lung transplantation, and 13 hospital admissions). The presence of EID was associated with poor clinical outcome (hazard ratio = 6.099, 95% confidence interval = 1.783–20.869, P = 0.004).ConclusionsDuring the 6MWT, EID was observed in a half of PAH patients and emerged as a significant prognostic marker for adverse clinical events.Graphical

Study of exercise-induced desaturation in chronic obstructive pulmonary disease patients visiting tertiary care center in Bangalore

Background: Chronic obstructive pulmonary disease (COPD) patients often have a lower ability to exercise and muscle weakness, both decreasing their quality of life. The 6 min walk test (6MWT) offers insightful data on the functional capacity of respiratory variables on exercise performance. A significant reduction in oxygen saturation (SpO2) throughout the test signifies a lower tolerance for exercise or additional oxygen requirement. Aims and Objectives: This study focuses to investigate desaturation in COPD patients with normal resting oxygen levels (normoxemic) employing the 6MWT. The objective of the study defines to analyze different clinical parameters such as smoking behavior, 6MWT, and clinical parameters of COPD patients to diagnose respiratory performance. Materials and Methods: Between June 2019 and May 2020 study was conducted on patients presenting to our OPD, who were above 40 years and diagnosed with COPD, with baseline SpO2 ≥90%. 6MWT was performed on them as per American Thoracic Society guidelines. Noting their distance covered and desaturation if present. Results: The study group included 60 patients; the group was divided into 35 desaturators (DS) and 25 Non-DS (NDS) based on fall in SpO2 during 6MWT, all current smokers were in the DS group and had low body mass index values, DS group covered less distance when compared to NDS, DS had low mean forced vital capacity and forced expiratory volume 1 second values. Conclusion: This study established the relationship between COPD risk variables and 6MWT. The 6MWT was identified as a useful method to examine respiratory performance by noting exercise-induced desaturation and in turn the respiratory capacity among COPD patients.

The six-minute walk test - a reliable test for detection of exercise-related desaturation in patients with chronic obstructive pulmonary disease.

Exercise-induced desaturation is common in patients with moderate to severe chronic obstructive pulmonary disease (COPD). It provides additional information about physical capacity and disease evolution, and it is an important predictor of mortality.

A remote monitoring-enabled home exercise prescription for patients with interstitial lung disease at risk for exercise-induced desaturation

RationaleAlternatives to center-based pulmonary rehabilitation are needed to improve patient access to this important therapy. A critical challenge to overcome is how to maximize safety of unsupervised exercise for at-risk patients. We investigated if a novel remote monitoring-enabled mobile health (mHealth) program is safe, feasible, and effective for patients who experience exercise-induced hemoglobin desaturation. MethodsAn interstitial lung disease (ILD) commonly associated with pronounced exercise desaturation was investigated - the rare, female-predominant ILD lymphangioleiomyomatosis (LAM). Over a 12-week program, hemoglobin saturation (SpO2) was continuously recorded during all home exercise sessions. Intervention effects were assessed with 6-min walk test (6MWT), maximal cardiopulmonary exercise test (CPET), lower extremity computerized dynamometry, pulmonary function tests, and health-related quality of life (QoL) surveys. Safety was assessed by blood biomarkers of systemic inflammation and cardiac wall stress, and incidence of adverse events. ResultsFifteen LAM patients enrolled and 14 completed the intervention, with high adherence to aerobic (87 ± 15%) and strength (87 ± 12%) training components. An innovative characterization of exercise training SpO2 revealed that while mild-to-moderate desaturation was common during home workouts, participants were able to self-adjust exercise intensity and supplemental oxygen levels to maintain recommended exercise parameters. Significant improvements included 6MWT distance (+36 ± 34 m, p = 0.003), CPET time (p = 0.04), muscular endurance (p = 0.008), QoL (p = 0.009 to 0.03), and fatigue (p = 0.001 to 0.03). Patient acceptability and satisfaction indicators were high, blood biomarkers remained stable (p > 0.05), and no study-related adverse events occurred. ConclusionA remote monitoring-enabled home exercise program is a safe, feasible, and effective approach even for patients who experience exercise desaturation.

Automated O2 Titration Alone or With High-Flow Nasal Cannula During Walking Exercise in Chronic Lung Diseases.

Exercise-induced O2 desaturation contributes to dyspnea and exercise intolerance in various respiratory diseases. This study assessed whether automated O2 titration was superior to fixed-flow O2 to improve exertional dyspnea and walking exercise endurance. We also aimed at evaluating possible additive effects of high-flow nasal cannula coupled with automated O2 titration on these outcomes. Subjects with chronic respiratory diseases and exercise-induced desaturation performed a 3-min constant-speed shuttle test (CSST) and an endurance shuttle walking test (ESWT) with either (1) fixed-flow O2, (2) automated O2 titration targeting an SpO2 of 94% (± 2%), and (3) automated O2 titration + high-flow nasal cannula according to a randomized sequence. The main outcome was Borg dyspnea score at the end of the 3-min CSST. Secondary outcomes included endurance time and dyspnea during ESWT and oxygenation status during exercise. Ten subjects with COPD, 10 with interstitial lung disease, 5 with pulmonary hypertension, and 3 with cystic fibrosis completed the study. Compared to fixed-flow O2, automated O2 titration did not reduce dyspnea at the end of the 3-min CSST. Endurance time during the ESWT was prolonged with automated O2 titration (mean difference 298 [95% CI 205-391] s, P < .001), and dyspnea at isotime was reduced. No further improvement was noted when high-flow nasal cannula was added to automated O2 titration. Compared to fixed-flow O2, O2 flows were higher with automated O2 titration, resulting in better oxygenation. Automated O2 titration was superior to fixed-flow O2 to alleviate dyspnea and improve exercise endurance during the ESWT in subjects with a variety of chronic respiratory diseases. Adding high-flow nasal cannula to automated O2 titration provided no further benefits.

Survey of exercise testing and training in cystic fibrosis clinics in the UK: a decade of progress

ObjectivesRegular exercise testing is recommended for people with cystic fibrosis (pwCF), as is the provision and regular review of exercise training programmes. A previous survey on exercise testing and training...

Prediction of exercise-induced desaturation in COPD patients without resting hypoxemia: a retrospective study

BackgroundThere is no universally accepted criterion for assessing exercise-induced desaturation (EID). The purpose of this study is to compare the two methods regularly used for determining EID in COPD patients, as well as to explore the risk factors and predictors related to EID.MethodsThe 6MWT was performed with continuous SpO2 monitoring on patients with stable COPD. Using two methods (method A: “SpO2rest–SpO2min ≥ 4% and/or SpO2min < 90%”, method B: “SpO2rest–SpO2end ≥ 4% and/or SpO2end < 90%”) as EID determination criteria to assess the incidence of EID. The differences and consistency of the two methods are compared. Moreover, we collected data through the pulmonary function test, mMRC dyspnea score, COPD assessment test, BODE index and CT-defined emphysema. Univariate and multivariate logistic regression analyses were used to identify factors affecting the EID. For the parameters that predict EID in 6MWT, a receiver operating characteristic (ROC) curve analysis was employed.ResultsThe analysis included 124 patients. The overall incidence of EID was 62.1% by using method A as the criterion and 51.6% by method B. All of the EID patients found by method B were included in the EID patients identified by method A, as well as 13 new-EID patients. The difference in diagnostic outcomes between the two approaches was not statistically significant (P > 0.05), but they were in excellent agreement (Kappa = 0.807, P = 0.001). Logistic regression analyses found that DLCO SB% pred, DLCO/VA% pred, CAT score, mean density, PD15, emphysema volume and %LAA were significant determinants of the EID. For predicting EID, the ROC analysis produced AUC and cutoffs of 0.689 and 50.45% (DLCO SB% pred), 0.707 and 75.0% (DLCO/VA% pred), 0.727 and 15 points (CAT score), 0.691 and − 955.00HU (PD15), 0.671 and − 856.46HU (mean density), 0.668 and 338.14 ml (emphysema volume) and 0.656 and 7.63% (%LAA), respectively.ConclusionsTwo methods evaluating EID in this research are in a good agreement, method A can find more EID patients by focusing on SpO2min. When conditions are constrained, it is also sufficient to assess EID in COPD patients by method B. In terms of the predictors of EID, DLCO SB% pred, DLCO/VA% pred, CAT score and CT-defined emphysema are all statistically significant test variables to determine EID.

Voice Alterations, Dysarthria, and Respiratory Derangements in Patients With Parkinson's Disease.

Almost 90% of people with Parkinson's disease (PD) develop voice and speech disorders during the course of the disease. Ventilatory dysfunction is one of the main causes. We aimed to evaluate relationships between respiratory impairments and speech/voice changes in PD. At Day 15 from admission, in consecutive clinically stable PD patients in a neurorehabilitation unit, we collected clinical data as follows: comorbidities, PD severity, motor function and balance, respiratory function at rest (including muscle strength and cough ability), during exercise-induced desaturation and at night, voice function (Voice Handicap Index [VHI] and acoustic analysis [Praat]), speech disorders (Robertson Dysarthria Profile [RDP]), and postural abnormalities. Based on an arbitrary RDP cutoff, two groups with different dysarthria degree were identified-moderate-severe versus no-mild dysarthria-and compared. Of 55 patients analyzed (median value Unified Parkinson's Disease Rating Scale Part II 9 and Part III 17), we found significant impairments in inspiratory and expiratory muscle pressure (&gt; 90%, both), exercise tolerance at 6-min walking distance (96%), nocturnal (12.7%) and exercise-induced (21.8%) desaturation, VHI (34%), and Praat Shimmer% (89%). Patients with moderate-severe dysarthria (16% of total sample) had more comorbidities/disabilities and worse respiratory pattern and postural abnormalities (camptocormia) than those with no-mild dysarthria. Moreover, the risk of presenting nocturnal desaturation, reduced peak expiratory flow, and cough ability was about 11, 13, and 8 times higher in the moderate-severe group. Dysarthria and respiratory dysfunction are closely associated in PD patients, particularly nocturnal desaturation and reduced cough ability. In addition, postural condition could be at the base of both respiratory and voice impairments. https://doi.org/10.23641/asha.21210944.

Feasibility of the A-STEP for the assessment of exercise capacity in people with cystic fibrosis.

To evaluate feasibility of the Alfred Step Test Exercise Protocol (A-STEP) for the assessment of exercise capacity in adults and children with cystic fibrosis (CF); in adults to test whether demographics and/or lung function correlated with exercise capacity. Adults and children with stable CF from two centres completed the A-STEP (a recently developed incremental maximal-effort step test). Feasibility was evaluated by: usefulness for exercise capacity assessment (measures of exercise capacity were: level reached, exercise-induced desaturation, and achievement of at least one maximal effort criteria); safety; operational factors; time to complete; floor and/or ceiling effects. We used multiple linear regression to test whether demographics and/or lung function correlated with exercise capacity. A total of 49 participants: 38 adults (18 male), percent predicted (pp) forced expiration in one second (FEV1 ) 29-109, aged 22-48 years and 11 children (6 male), ppFEV1 68-107, aged 10-15 years were included. Levels reached (mean (SD) [range]) were 10.2 (2.4) [6-15] (adults), 10.1 (2.5) [7-14] (children); desaturation (change between baseline and peak-exercise SpO2 ): was 8.4 (3.8 [0-15]% (adults), 2.0 (2.0) [0-7]% (children). A total of 8 (21%) adults and no children desaturated <90% SpO2 . At least one criterion for maximal effort was reached by 33 (84%) adults and 10 (91%) children. There were no adverse events. The A-STEP was straightforward to use and carried out by one operator. A total of 26 (68.4%) adults and 7 (63.6%) children completed the test within the recommended 8-12 min. All participants completed a minimum of 6 levels, and completed the test before the final 16th level. In adults, ppFEV1 and ppFVC correlated with the level reached (r = 0.55; p = <0.001 and r = 0.66, p = <0.0001) and desaturation (r = 0.55, p = <0.001 and r = 0.45, p = <0.005). In adults and children with stable CF, the A-STEP was feasible, safe, and operationally easy to use for the assessment of exercise capacity, without floor or ceiling effects. In adults, lung function correlated with exercise capacity.

In-Patient Trajectories and Effects of Training in Survivors of COVID-19-Associated Acute Respiratory Failure.

Pulmonary rehabilitation (PR) is useful in survivors of COVID-19-associated acute respiratory failure (ARF). The aim of this retrospective study on in-patient PR was to report rehabilitative trajectories and effects of cycle training. According to the Short Physical Performance Battery (SPPB) score at admission (T0), participants were allocated to stage 1 (SPPB < 6), stage 2 (SPPB ≥ 6 and < 10), or stage 3 (SPPB ≥ 10) and performed increasing level of activities from passive exercises to free walking, balance exercises, strength exercises, and tailored cycle-ergometer endurance training. The primary outcome was SPPB. 6-min walk distance (6MWD), Medical Research Council score, Barthel dyspnea index, and rate of subjects able to cycling were also assessed. Data of 123 participants were analyzed. At T0, 44 (35.8%), 50 (40.6%), and 29 (23.6%) participants were allocated to stages 1-3, respectively. At discharge, participants showed significant improvements in SPPB, independent of the initial stage, 81 (65.8%) improving more than its minimal clinically important difference. At T1, the proportion of participants in stages 1 and 2 decreased, whereas significantly increased in stage 3 (P = .003), (being 9.8%, 33.3%, and 56.9% for stages 1-3, respectively; P <.001). Sixty-nine of 123 participants (56.1%) underwent cycle exercise training. In participants able to perform it, 6MWD improved by 115 (65-240) m and 60 (40-118) m in participants with and without exercise-induced desaturation, respectively, with significant difference between groups (P = .044). In-patient PR could be tailored and progressively increased to survivors of COVID-19-associated ARF; cycle training was feasible in half of the participants. Benefits were independent of initial stage of physical performance and allowed participants to move from lower to higher levels of activities.

Association of air pollution exposure with exercise-induced oxygen desaturation in COPD

BackgroundThere is a link between exposure to air pollution and the increased prevalence of chronic obstructive pulmonary disease (COPD) and declining pulmonary function, but the association with O2 desaturation during exercise in COPD patients with emphysema is unclear. Our aims were to estimate the prevalence of O2 desaturation during exercise in patients with COPD, and determine the association of exposure to air pollution with exercise-induced desaturation (EID), the degree of emphysema, and dynamic hyperinflation (DH).MethodsWe assessed the effects of 10-year prior to the HRCT assessment and 7 days prior to the six-minute walking test exposure to particulate matter with an aerodynamic diameter of < 10 µm (PM10) or of < 2.5 µM (PM2.5), nitrogen dioxide (NO2), and ozone (O3) in patients with emphysema in this retrospective cohort study. EID was defined as a nadir standard pulse oximetry (SpO2) level of < 90% or a delta (△)SpO2 level of ≥ 4%. Ambient air pollutant (PM2.5, PM10, O3, and NO2) data were obtained from Taiwan Environmental Protection Administration (EPA) air-monitoring stations, usually within 10 km to each participant’s home address.ResultsWe recruited 141 subjects with emphysema. 41.1% of patients with emphysema exhibited EID, and patients with EID had more dyspnea, worse lung function, more severe emphysema, more frequent acute exacerbations, managed a shorter walking distance, had DH, and greater long-term exposure to air pollution than those without EID. We observed that levels of 10-year concentrations of PM10, PM2.5, and NO2 were significantly associated with EID, PM10 and PM2.5 were associated with the severity of emphysema, and associated with DH in patients with emphysema. In contrast, short-term exposure did not have any effect on patients.ConclusionLong-term exposure to ambient PM10, PM2.5 and NO2, but not O3, was associated with EID.

Characteristics of COVID-19 Pneumonia Survivors With Resting Normoxemia and Exercise-Induced Desaturation.

Survivors of coronavirus disease 2019 (COVID-19) associated pneumonia may show exercise-induced desaturation. We wondered whether these individuals show physiologic and symptom characteristics similar to individuals with chronic respiratory diseases with exercise-induced desaturation, namely COPD or interstitial lung diseases (ILD). We evaluated lung function, exercise capacity, and symptoms in these individuals compared with individuals with COPD or ILD and exercise-induced desaturation. Survivors of COVID-19 associated pneumonia (study individuals), normoxemic at rest with exercise-induced desaturation, underwent assessment of dyspnea, dynamic lung volumes, carbon monoxide diffusion capacity, and the 6-min walk test. Data of individuals with COPD or with ILD and exercise-induced desaturation were also retrospectively analyzed. FVC was lower in individuals with COVID-19 or ILD than in those with COPD. Individuals who had COVID-19 walked < 70% of predicted and, as a whole, had a 6-min walk test performance similar to individuals with ILD but walked significantly less, showed more severe leg fatigue and dyspnea during exercise, and more exercise-induced desaturation than individuals with COPD. Survivors of COVID-19 associated pneumonia, who were normoxemic at rest with exercise-induced desaturation, had alterations in lung function, exercise capacity, and symptoms similar to individuals with ILD but more severe than individuals with COPD and exercise-induced desaturation.

CT-defined emphysema in COPD patients and risk for change in desaturation status in 6-min walk test

BackgroundEmphysema and exercise induced desaturation (EID) are both related to poorer COPD prognosis. More knowledge of associations between emphysema and desaturation is needed for more efficient disease management. Research questionIs emphysema a risk factor for both new and repeated desaturation, and is emphysema of more or less importance than other known risk factors? Methods283 COPD patients completed a 6-min walk test (6MWT) at baseline and one year later in the Bergen COPD cohort study 2006–2011. Degree of emphysema was assessed as percent of low attenuation areas (%LAA) under −950 Hounsfield units using high-resolution computed tomography at baseline.We performed multinomial logistic regression analysis, receiver operating curves (ROC) and area under the curve (AUC) estimations. Dominance analysis was used to rank emphysema and risk factors in terms of importance. ResultsA one percent increase in %LAA increases the relative risk (RR) of new desaturation by 10 % (RR 1.1 (95%CI 1.1, 1.2)) and for repeated desaturation by 20 % (RR 1.2 (95%CI 1.1, 1.3)). Compared with other important desaturation risk factors, %LAA ranked as number one in the dominance analysis, accounting for 50 % and 37 % of the predicted variance for new and repeated desaturators, respectively. FEV1% predicted accounted for 9 % and 24 %, and resting SpO2 accounted for 22 % and 21 % for new and repeated desaturation. ConclusionEmphysema increases the risk of developing and repeatedly experiencing EID. Emphysema seems to be a more important risk factor for desaturation than FEV1% predicted and resting saturation.