Exercise response to oxygen supplementation is not associated with survival in hypoxemic patients with obstructive lung disease

The impact of body mass index on mortality in COPD: an updated dose-response meta-analysis

BACKGROUND AND OBJECTIVE

The obesity paradox is a well-established clinical conundrum in COPD patients. This study aimed to provide an updated analysis of the relationship between body mass index (BMI) and mortality in this population.

METHODS

A systematic search was conducted through Embase, PubMed, and Web of Science. International BMI cut-offs were employed to define underweight, overweight and obesity. The primary outcome was all-cause mortality, and the secondary outcome was respiratory and cardiovascular mortality.

RESULTS

120 studies encompassed a total of 1 053 272 patients. Underweight status was associated with an increased risk of mortality, while overweight and obesity were linked to a reduced risk of mortality. A nonlinear U-shaped relationship was observed between BMI and all-cause mortality, respiratory mortality and cardiovascular mortality. Notably, an inflection point was identified at BMI 28.75 kg·m-2 (relative risk 0.83, 95% CI 0.80-0.86), 30.25 kg·m-2 (relative risk 0.51, 95% CI 0.40-0.65) and 27.5 kg·m-2 (relative risk 0.76, 95% CI 0.64-0.91) for all-cause, respiratory and cardiovascular mortality, respectively, and beyond which the protective effect began to diminish.

CONCLUSION

This study augments the existing body of evidence by confirming a U-shaped relationship between BMI and mortality in COPD patients. It underscores the heightened influence of BMI on respiratory and cardiovascular mortality compared to all-cause mortality. The protective effect of BMI was lost when BMI values exceeded 35.25 kg·m-2, 35 kg·m-2 and 31 kg·m-2 for all-cause, respiratory and cardiovascular mortality, respectively.

Thoracic Society of Australia and New Zealand clinical practice guideline on adult home oxygen therapy

This Thoracic Society of Australia and New Zealand Guideline on the provision of home oxygen therapy in adults updates a previous Guideline from 2015. The Guideline is based upon a systematic review and meta-analysis of literature to September 2022 and the strength of recommendations is based on GRADE methodology. Long-term oxygen therapy (LTOT) is recommended for its mortality benefit for patients with COPD and other chronic respiratory diseases who have consistent evidence of significant hypoxaemia at rest (PaO2 ≤ 55 mm Hg or PaO2 ≤59 mm Hg in the presence of hypoxaemic sequalae) while in a stable state. Evidence does not support the use of LTOT for patients with COPD who have moderate hypoxaemia or isolated nocturnal hypoxaemia. In the absence of hypoxaemia, there is no evidence that oxygen provides greater palliation of breathlessness than air. Evidence does not support the use of supplemental oxygen therapy during pulmonary rehabilitation in those with COPD and exertional desaturation but normal resting arterial blood gases. Both positive and negative effects of LTOT have been described, including on quality of life. Education about how and when to use oxygen therapy in order to maximize its benefits, including the use of different delivery devices, expectations and limitations of therapy and information about hazards and risks associated with its use are key when embarking upon this treatment.

Patient Use Patterns of Portable Oxygen Concentrators

INTRODUCTION

Portable oxygen concentrators (POCs) are medical devices that provide supplemental oxygen to patients requiring long-term oxygen therapy. However, little information is available on day-to-day patterns of how or even whether patients actively switch between their POC mobility features and flow setting options.

METHODS

A retrospective analysis was conducted to assess POC usage among patients who used an Inogen One G5 POC in the USA. This study aimed (1) to describe the patterns of use of POCs, (2) to analyze their compatibility with the prescribed oxygen therapy settings, and (3) to demonstrate the contribution of POC usage to get a standardized long-term oxygen therapy (LTOT). Data were directly downloaded from the devices returned for service or at the end of the Medicare Durable Medical Equipment rental period and streamed via a mobile application from 2018 to 2022. Daily usage, disconnections from the device, use of prescribed pulse delivery settings, breaths per minute, power sources, and movement with the POC were assessed. Device alert histories were also examined.

RESULTS

Data revealed a mean daily usage of 4.29 ± 3.23 h/day, ranging from 0.35 to 15.52 h/day. The prescribed pulse delivery setting was used by 31.34% of patients for at least 80% of their POC use time. When the POC was on battery power, patients were moving/mobile 41.99 ± 33.33% of the time. On the basis of the device-generated alerts, some patients continued to use their POC very close to or even beyond the lifetime of the column/sieve bed. Alerts or alarms potentially requiring repair occurred at a rate of 1.63 events per 100 years of use, indicating that device reliability did not significantly influence the use patterns.

CONCLUSION

Patients used their POCs when mobile and at rest. A large proportion of patients adjust their POC settings during the day, which potentially indicates the need for the dynamic individualization of oxygen dose delivery to match activities of daily living or sleep. Patients require follow-up to ensure timely replacement of POC columns.

Cardiorespiratory coupling is associated with exercise capacity in athletes: A cross-sectional study

PURPOSE

To determine the association between exercise capacity based on peak oxygen uptake (VO2peak) and resting cardiorespiratory coupling (CRC) levels in athletes and non-athletes' subjects.

METHODS

A cross-sectional study was carried out in 42 apparently healthy male subjects, aged between 20 and 40 years old. The participants were allocated into athletes (n = 21) and non-athletes (n = 21) groups. Resting electrocardiogram and respiratory movement (RESP) were simultaneously acquired during 15 min in supine position and quiet breathing. The beat-to-beat heart period (HP) and RESP series were determined from the recorded signals. Traditional analysis of HP based on frequency domain indexes was performed considering the high-frequency (0.15 - 0.45 Hz) components. To compute the CRC, the linear association between HP and RESP series was determined via squared coherence function and directionality of interaction was investigated through the causal extension of this approach. The exercise capacity was assessed through incremental cardiopulmonary exercise testing in order to determine the VO2peak.

RESULTS

Traditional analysis of HP based on high-frequency index was not correlated with exercise capacity in the athletes (r = -0.1, p = 0.5) and non-athletes (r = -0.1, p = 0.3) cohorts. However, resting CRC values was associated with exercise capacity in athletes (r = 0.4, p = 0.03), but not in the non-athletes group (r = -0.2, p = 0.3).

CONCLUSION

These results suggest that improved resting values of CRC is associated with higher exercise capacity (VO2peak) in endurance athletes. Moreover, frequency domain of HP was not sensitive to identifying this relationship, probably because effects of training on parasympathetic modulation might be affected by respiratory dynamics, and this influence has a directionality (i.e., from RESP to HP).

Dietary nitrate supplementation to enhance exercise capacity in hypoxic COPD: EDEN-OX, a double-blind, placebo-controlled, randomised cross-over study

RATIONALE

Dietary nitrate supplementation improves skeletal muscle oxygen utilisation and vascular endothelial function. We hypothesised that these effects might be sufficient to improve exercise performance in patients with COPD and hypoxia severe enough to require supplemental oxygen.

METHODS

We conducted a single-centre, double-blind, placebo-controlled, cross-over study, enrolling adults with COPD who were established users of long-term oxygen therapy. Participants performed an endurance shuttle walk test, using their prescribed oxygen, 3 hours after consuming either 140 mL of nitrate-rich beetroot juice (BRJ) (12.9 mmol nitrate) or placebo (nitrate-depleted BRJ). Treatment order was allocated (1:1) by computer-generated block randomisation.

MEASUREMENTS

The primary outcome was endurance shuttle walk test time. The secondary outcomes included area under the curve to isotime for fingertip oxygen saturation and heart rate parameters during the test, blood pressure, and endothelial function assessed using flow-mediated dilatation. Plasma nitrate and nitrite levels as well as FE_NO were also measured.

MAIN RESULTS

20 participants were recruited and all completed the study. Nitrate-rich BRJ supplementation prolonged exercise endurance time in all participants as compared with placebo: median (IQR) 194.6 (147.5-411.7) s vs 159.1 (121.9-298.5) s, estimated treatment effect 62 (33-106) s (p<0.0001). Supplementation also improved endothelial function: NR-BRJ group +4.1% (-1.1% to 14.8%) vs placebo BRJ group -5.0% (-10.6% to -0.6%) (p=0.0003).

CONCLUSION

Acute dietary nitrate supplementation increases exercise endurance in patients with COPD who require supplemental oxygen.Trial registration number ISRCTN14888729.

Alpha1-antitrypsin Disease, Treatment and Role for Lung Volume Reduction Surgery

Chronic obstructive pulmonary usually is subcategorized into 2 groups: chronic bronchitis and emphysema. The main cause of chronic bronchitis and emphysema is smoking; however, alpha1-antitrypsin also has been seen to cause emphysema in patients who are deficient. As symptoms and lung function decline, treatment modalities, such as lung volume reduction surgery, have been used in individuals with chronic obstructive pulmonary disease and upper lobe predominant emphysema. This article analyzes multiple published series where lung volume reduction surgery has been used in individuals with alpha1-antitrypsin deficiency and their overall outcomes.

Cardiorespiratory coupling is associated with exercise capacity in patients with chronic obstructive pulmonary disease

Background

The interaction between the pulmonary function and cardiovascular mechanics is a crucial issue, particularly when treating patients with chronic obstructive pulmonary disease (COPD). Synchrogram index is a new parameter that can quantify this interaction and has the potential to apply in COPD patients. Our objective in this study was to characterize cardiorespiratory interactions in terms of cardiorespiratory coupling (CRC) using the synchrogram index of the heart rate and respiratory flow signals in patients with chronic obstructive pulmonary disease.

Methods

This is a cross-sectional and preliminary data from a prospective study, which examines 55 COPD patients. K-means clustering analysis was applied to cluster COPD patients based on the synchrogram index. Linear regression and multivariable regression analysis were used to determine the correlation between the synchrogram index and the exercise capacity assessed by a six-minute walking test (6MWT).

Results

The 55 COPD patients were separated into a synchronized group (median 0.89 (0.64–0.97), n = 43) and a desynchronized group (median 0.23 (0.02–0.51), n = 12) based on K-means clustering analysis. Synchrogram index was correlated significantly with six minutes walking distance (r = 0.42, p = 0.001) and distance saturation product (r = 0.41, p = 0.001) assessed by 6MWT, and still was an independent variable by multivariable regression analysis.

Conclusion

This is the first result studying the heart–lung interaction in terms of cardiorespiratory coupling in COPD patients by the synchrogram index, and COPD patients are clustered into synchronized and desynchronized groups. Cardiorespiratory coupling is associated with exercise capacity in patients with COPD.

Exercise and Chronic Obstructive Pulmonary Disease (COPD)

Systemic effects of COPD lead to cardiovascular co-morbidities, muscle wasting and osteoporosis that, in turn, lead to inactivity and physical deconditioning. This evolution has a direct influence on the health-related quality of life (HRQoL) of patients suffering from this respiratory disease. Pharmacological therapy leads to improvement in shortness of breath, but it has a limited effect on the physical deconditioning. Pulmonary rehabilitation relieves dyspnoea and fatigue, improves emotional function and enhances the sense of control that individuals have over their condition. These improvements are moderately substantial and clinically significant. Rehabilitation serves as an essential component of the management of COPD and is beneficial in improving health-related quality of life and exercise capacity.