Long-term oxygen therapy in COPD patients: population-based cohort study on mortality

[Take-home messages from the 2nd COPD 2023 Biennial of the French Society of Respiratory Diseases. Placing the patient at the center of the care pathway]

INTRODUCTION

The second COPD Biennial organized by the COPD working group of the French Society of Respiratory Diseases took place in Paris (Cochin) on 13th December 2023.

STATE OF THE ART

Major trends in 2023 were discussed; they encompassed concepts, definitions, biologics, care pathways, pulmonary rehabilitation and complex situations entailed by respiratory infections, cardiovascular comorbidities and pulmonary hypertension, and modalities of oxygen therapy and ventilation.

PERSPECTIVES

The different talks underlined major changes in COPD including the concepts of pre-COPD, etiotypes, health trajectories and new definitions of exacerbation. Recent results in biologics for COPD open the door to new pharmacological options. Assessment of current care pathways in France highlighted some causes for concern. For example, pulmonary rehabilitation is a key but insufficiently practiced element. Respiratory infections require careful assessment and treatments. Diagnosis and treatment of cardiovascular comorbidities and pulmonary hypertension are of paramount importance. As of late, oxygen therapy and ventilation modalities have evolved, and are beginning to afford more personalized options.

CONCLUSIONS

As regards COPD, a personalized approach is crucial, placing the patient at the center of the care pathway and facilitating coordination between healthcare providers.

Nanocurcumin supplementation improves pulmonary function in severe COPD patients: A randomized, double blind, and placebo-controlled clinical trial

Considering the anti-inflammatory properties of curcumin, the present study was designed to investigate the effect of nano-curcumin on respiratory indices and interleukin-6 (IL-6) levels in severe chronic obstructive pulmonary disease (COPD) patients as a common pulmonary disease causing restricted airflow and breathing problems. In the current double-blind placebo-controlled randomized clinical trial study, 60 patients with stages 3 and 4 COPD were randomly assigned into 80 mg nano-curcumin (n = 30) and placebo groups (n = 30) for 3 months. The effect of nano-curcumin on pulmonary function was evaluated by the first second of forced expiration (FEV1) to the full, forced vital capacity (FVC) ratio. IL-6 serum level, blood pressure, and anthropometric indices were also measured. Nano-curcumin supplementation led to a significant decrease in IL-6 level (p < 0.001) and an increase in FEV1 (p < 0.001), FVC (p = 0.003), and FEV1/FVC (p < 0.001) compared to placebo at the endpoint. Nano-curcumin had a significantly increasing effect on weight and body mass index compared to the placebo group (PANCOVA adjusted for baseline values  = 0.042). There was a meaningful improvement in systolic blood pressure in the nano-curcumin group compared to the placebo group (PANCOVA adjusted for baseline values  = 0.026). There was no significant difference between the two groups in terms of waist circumference, waist-to-hip ratio, and diastolic blood pressure (PANCOVA adjusted for baseline values >0.05). Nano-curcumin supplement seems to have favorable effects on inflammation status and respiratory indices of patients with severe COPD.

Association Between Rome Classification Among Hospitalized Patients With COPD Exacerbations and Short-Term and Intermediate-Term Outcomes

BACKGROUND

Recently, the Rome proposal updated the definition of exacerbation of COPD (ECOPD). However, such severity grade has not yet demonstrated intermediate-term clinical relevance.

RESEARCH QUESTION

What is the association between the Rome severity classification and short-term and intermediate-term clinical outcomes?

STUDY DESIGN AND METHODS

We retrospectively grouped hospitalized patients with ECOPD according to the Rome severity classification (ie, mild, moderate, severe). Baseline, clinical, microbiologic, gas analysis, and laboratory variables were collected. In addition, data about the length of hospital stay and mortality (in-hospital and a follow-up time line from 6 months until 3 years) were assessed.

RESULTS

Of the 347 hospitalized patients, 39% were categorized as mild, 31% were categorized as moderate, and 30% were categorized as severe. Overall, patients with severe ECOPD had an extended length of hospital stay. Although in-hospital mortality was similar among groups, patients with severe ECOPD presented a worse prognosis in all follow-up time points. The Kaplan-Meier curves show the role of the severe classification in the cumulative survival at 1 and 3 years (Gehan-Breslow-Wilcoxon test, P = .032 and P = .004, respectively). The multivariable Cox regression analysis showed a higher risk of death at 1 year when patients presented a severe (hazard ratio, 1.99; 95% CI, 1.49-2.65) or moderate grade (hazard ratio, 1.47; 95% CI, 1.10-1.97) compared with a mild grade. Older patients (aged ≥ 80 years), patients requiring long-term oxygen therapy, or patients reporting previous ECOPD episodes had a higher mortality risk. A BMI between 25 and 29 kg/m2 was associated with a lower risk.

INTERPRETATION

The Rome classification makes it possible to discriminate patients with a worse prognosis (severe or moderate) until a 3-year follow-up.

Acceptance and adherence to non-invasive positive pressure ventilation in people with chronic obstructive pulmonary disease: a grounded theory study

Introduction

Non-Invasive Positive Pressure Ventilation (NPPV) is an established treatment for people with Chronic Obstructive Pulmonary Disease (COPD), but it is often improperly used or rejected. The patterns of acceptance and adherence to NPPV, conceiving constraints, and strengths related to its adaptation have not been explored from a qualitative perspective yet.

Objectives

This study aims to qualitatively explore patterns of adaptation to NPPV in people affected by COPD and to identify the core characteristics and the specific adaptive challenges during the adaptation process.

Methods

Forty-two people with moderate or severe COPD were recruited and 336 unstructured interviews were conducted. A Constructivist Grounded Theory was used to gather and analyze data: the transcriptions were mutually gathered in open, selective, and theoretical phases, with open, selective, and theoretical coding, respectively.

Results

The analysis resulted in a non-linear and dynamic process, characterized by three phases: deciding, trying NPPV, and using NPPV. The patterns revealed that positive and negative NPPV experiences, together with beliefs, emotions, stressful mental states, and behaviors result in different acceptance and adherence rates.

Discussions

These findings may be helpful to implement new care strategies to promote acceptance and adherence to NPPV.

Performance of Different Low-Flow Oxygen Delivery Systems

BACKGROUND

The delivery of a high and consistent [Formula: see text] is imperative to treat acute hypoxemia. The objective of this study was to analyze the effective inspired oxygen concentration delivered by different low-flow oxygen therapy systems challenged with different oxygen flows and respiratory patterns in an experimental lung model.

METHODS

An adult lung model ventilated in volume control mode simulated different respiratory patterns to obtain mean inspiratory flow of 22.5, 30.0, 37.5, or 45.0 L/min. The oxygen concentration sampled inside the lung model by nasal cannula, simple face mask, non-rebreather mask, and double-trunk mask above nasal cannula tested at oxygen flows of 10, 12.5, and 15 L/min was quantified. The 3 masks were sealed tight onto the model's airway opening. They were also tested with standardized leaks to determine their clinical performance.

RESULTS

All oxygen delivery systems delivered higher oxygen concentration with increasing oxygen flows, regardless of the respiratory pattern. Within each device, the increase in inspiratory flow decreased oxygen concentration when using nasal cannula (P = .03), the simple face mask (P = .03), but not the non-rebreather mask (P = .051) nor the double-trunk mask (P = .13). In sealed condition, the double-trunk mask outperformed the non-rebreather mask and simple face mask (P < .001); mean oxygen concentration was 84.2%, 68.5%, and 60.8%, respectively. Leaks amplified oxygen concentration differences between the double-trunk mask and the other masks as the oxygen delivery decreased by 4.6% with simple face mask (95% CI 3.1-6.1%, P < .001), 7.8% with non-rebreather mask (95% CI 6.3-9.3%, P < .001), and 2.5% with double-trunk mask (95% CI 1-4%, P = .002). With leaks, the oxygen concentration provided by the simple face mask and the non-rebreather mask was similar (P = .15).

CONCLUSIONS

Lung oxygen concentration values delivered by the double-trunk mask were higher than those obtained with other oxygen delivery systems, especially when leaks were present.

Association between long-term oxygen therapy provided outside the guidelines and mortality in patients with COPD

INTRODUCTION

Hypoxaemia is a frequent complication of chronic obstructive pulmonary disease (COPD). To prevent its consequences, supplemental oxygen therapy is recommended by international respiratory societies. However, despite clear recommendations, some patients receive long-term oxygen therapy (LTOT), while they do not meet prescription criteria. While evidence suggests that acute oxygen supply at high oxygenation targets increases COPD mortality, its chronic effects on COPD mortality remain unclear. Thus, the study will aim to evaluate through a systematic review and individual patient data meta-analysis (IPD-MA), the association of LTOT prescription outside the guidelines on survival over time in COPD.

METHODS

Systematic review and IPD-MA will be conducted according to Preferred Reporting Items for a Systematic Review and Meta-Analyses IPD guidelines. Electronic databases (PubMed, Web of Science, EMBASE, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, OpenGrey and BioRxiv/MedRxix) will be scanned to identify relevant studies (cohort of stable COPD with arterial oxygen tension data available, with indication of LTOT filled out at the moment of the study and with a survival follow-up). The anticipated search dates are January-February 2022. The main outcome will be the association between LTOT and time to all-cause mortality according to hypoxaemia severity, after controlling for potential covariates and all available clinical characteristics. Quantitative data at the level of the individual patient will be used in a one-step approach to develop and validate a prognostic model with a Cox regression analysis. The one-step IPD-MA will be conducted to study the association and the moderators of association between supplemental oxygen therapy and mortality. Multilevel survival analyses using Cox-mixed effects models will be performed.

ETHICS AND DISSEMINATION

As a protocol for a systematic review, a formal ethics committee review is not required. Only studies with institutional approval from an ethics committee and anonymised IPD will be included. Results will be disseminated through peer-reviewed publications and presentations in conferences.

PROSPERO REGISTRATION NUMBER

CRD42020209823.

Impact of Oxygen Concentration Delivered via Nasal Cannula on Different Lung Conditions: A Bench Study

BACKGROUND

Measuring the fraction of inspired oxygen (FiO2) is challenging in spontaneously breathing patients with impaired respiratory mechanics during low-flow nasal cannula. Our study investigates the FiO2 with varied tidal volume (VT) and respiratory rate (RR) among different lung mechanics and provides equations to estimate the FiO2.

METHODS

Two training and test lungs were used in this study, and the three lung mechanics (normal (R5/C60), restrictive (R20/C80), obstructive (R5/C40)) were designed. Spontaneous breathing with VT (300, 500, and 700 mL) and RR (10, 20, and 30 breaths/min) was simulated. The flow rate of the nasal cannula was set to 1, 3, and 5 L per minute (LPM), and the FiO2 was measured at the carina.

RESULTS

The lowest and highest FiO2 were evident during high (700 mL) and low VT (300 mL), respectively, among normal, restrictive, and obstructive lung models. As RR increases, this decreases the FiO2. However, we found that VT and oxygen flow rate are the principal factors influencing measured FiO2 by multiple linear regression analysis.

CONCLUSIONS

Our data suggest that the actual FiO2 is never as high in spontaneously breathing patients as that estimated. VT and oxygen flow rate had a substantial impact on the FiO2.

Life Expectancy and Rate of Decline After Lung Volume Reduction Surgery

Lung volume reduction surgery (LVRS) patient selection guidelines are based on the National Emphysema Treatment Trial. Because of increased mortality and poor improvement in functional outcomes, patients with non-upper lobe emphysema and low baseline exercise capacity are determined as poor candidates for LVRS. In well-selected patients with heterogeneous emphysema, LVRS has a durable long-term outcome at up to 5-years of follow-up. Five-year survival rates in patients range between 63% and 78%. LVRS seems a durable alternative for end-stage heterogeneous emphysema in patients not eligible for lung transplantation. Future studies will help identify eligible patients with homogeneous emphysema for LVRS.

Factors Associated with Treatment Failure in Patients with Acute Exacerbation of COPD Admitted to the Emergency Department Observation Unit

Objective

We aimed to identify factors associated with treatment failure in patients with acute exacerbation of COPD (AECOPD) admitted to the emergency department observation unit (EDOU).

Methods

A retrospective cohort study was conducted between January 1, 2013, and October 31, 2019. The electronic medical records were reviewed of patients with AECOPD admitted to the EDOU. The patients were divided into treatment failure and treatment success groups. Treatment failure was defined as prolonged stay at the EDOU (>48 h) or COPD-related ED revisit (within 72 h) or readmission within 1 month. The two groups were compared and analyzed using univariable and multivariable analyses by logistic regression.

Results

Of the 220 patients enrolled, 82 (37.3%) developed treatment failure. Factors associated with treatment failure included arrhythmias (odds ratio [OR] 3.8, 95% confidence interval [CI] 1.04–13.9), diabetic mellitus (OR 2.32, 95% CI 1.09–4.95), long-term oxygen therapy (OR 2.89, 95% CI 1.08–7.72), short-acting beta-agonist use (OR 6.06, 95% CI 1.98–18.62), pneumonia findings on chest X-ray (OR 3.24, 95% CI 1.06–9.95), and ED length of stay less than 4 h (OR 2, 95% CI 1.08–3.73).

Conclusion

Arrhythmias, diabetic mellitus, long-term oxygen therapy, short-acting beta-agonist use, pneumonia findings on chest X-ray, and ED length of stay <4 h were the significant factors associated with treatment failure of AECOPD to which physicians at the ED should pay special attention before the admission of patients to the EDOU.

Thorpe tube and oxygen flow restrictor: what's flow accuracy?

Oxygen gas flowmeters (OGF) are used to regulate the oxygen flow in acute and chronic care. In hospitals, Thorpe tubes (TT) are the classical systems most used for delivering oxygen. In recent years, the oxygen flow restrictor (OFR) has appeared. These devices use a series of calibrated openings in a disk that can be adjusted to deliver different flow rates. These devices have a reputation for delivering more accurate oxygen flow rates compared to classical OGFs. However, to our knowledge, few study has examined this supposition. This study aimed to compare and evaluate the accuracy and precision of the ready-to-use TTs and OFRs. OGFs were selected from hospitals in Belgium and France. Before performing the flow measurements, the inlet pressure was checked. The accuracy of the OGF was analyzed with a calibrated thermal mass flowmeter (RED Y COMPACT™ GCM-0 to 20 L/min-VÖGTLIN Instruments). Different flows (2, 4, 6, 9 or 12 L/min) were evaluated. Linear regression analysis, bias (with confidence interval) and lower and upper limit of the agreement were calculated for TTs and OFRs. All measurements are expressed in absolute values. Four-hundred-seventy-six TTs and 96 OFRs were analyzed. The intra-class correlation coefficient calculated for the calibrated thermal mass flowmeter was > 0.99 and reflected the excellent reliability of our measurements. For TTs, the bias value was - 0.24 L/min (± 0.88), and the limits of agreement were - 1.97 to 1.48 L/min. For OFRs, the bias value was - 0.30 L/min (± 0.54), and the limits of agreement were - 1.36 to 0.77 L/min. As the flow increased, the accuracy of all analyzed OGFs decreased. With the increasing flow, some data fell outside the limits of agreement, and the trend increased with the elevated oxygen flow. TTs were less accurate compared to OFRs due to the increased flow variability. However, for TTs and OFRs, as the required flow is elevated, the dispersion of values increases on both sides of the actual flow.