Methacholine-Induced Variations in Airway Volume and the Slope of the Alveolar Capnogram Are Distinctly Associated with Airflow Limitation and Airway Closure

Chronic obstructive pulmonary disease (COPD) is a respiratory illness characterized by airflow limitation and chronic respiratory symptoms with a global prevalence estimated to be more than 10% in 2010 and still on the rise. Furthermore, hypercapnic subject COPD leads to an increased risk of mortality, morbidity, and poor QoL (quality of life) than normocapnic subjects. Series of studies showed the usefulness of the forced oscillation technique (FOT) to measure small airway closure. Traditional findings suggested that hypercapnia may not be the main treating targets, but recent findings suggested that blood stream CO2 may lead to a worse outcome. This study aimed to seek the relationship between CO2 and small airway closure by using FOT. Subjects with COPD (n = 124; hypercapnia 22 and normocapnia 102) were analyzed for all pulmonary function values, FOT values, and arterial blood gas analysis. Student’s t-test, Spearman rank correlation, and multi linear regression analysis were used to analyze the data. COPD subjects with hypercapnia showed a significant increase in R5, R20, Fres, and ALX values, and a greater decrease in X5 value than normocapnic patients. Also, multiple linear regression analysis showed R5 was associated with hypercapnia. Hypercapnia may account for airway closure among subjects with COPD and this result suggests treating hypercapnia may lead to better outcomes for such a subject group.

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Faculty Opinions recommendation of Non-atopic males with adult onset asthma are at risk of persistent airflow limitation.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.714597881.790202801 ◽

2012 ◽

Author(s):

Harold Nelson

Keyword(s):

At Risk ◽

Airflow Limitation ◽

Adult Onset

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Faculty Opinions recommendation of Efficacy and safety of twice-daily glycopyrrolate in patients with stable, symptomatic COPD with moderate-to-severe airflow limitation: the GEM1 study.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.726610826.793532744 ◽

2017 ◽

Author(s):

Ravi Kalhan ◽

Sharon R Rosenberg

Keyword(s):

Airflow Limitation ◽

Efficacy And Safety

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Impact of artificial airway resistances on regional ventilation distribution during airway closure

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2020-3009 ◽

2020 ◽

Vol 6 (3) ◽

pp. 32-35

Author(s):

Melanie März ◽

Sarah Howe ◽

Bernhard Laufer ◽

Knut Moeller ◽

Sabine Krueger-Ziolek

Keyword(s):

Pulmonary Function ◽

Airway Resistance ◽

Airway Closure ◽

Ventilation Distribution ◽

Regional Ventilation ◽

Impedance Tomography ◽

Artificial Airway ◽

Normal Breathing ◽

Airway Obstructions ◽

Forced Breathing

AbstractElectrical impedance tomography (EIT), a noninvasive and radiation-free imaging technique can be used in pulmonary function monitoring for determining regional ventilation distribution within the lung. Gold standard in pulmonary function monitoring is spirometry/body plethysmography, a method using forced breathing maneuvers to obtain global lung function parameters. However, this method is heavily dependent on the cooperation of the patients. Within this observational study, a method under normal breathing was tested with 5 healthy volunteers, which provides regional information about ventilation distribution. The occlusion method Rocc, a method for determining airway resistance, was used to create a short-term airway closure. Regional ventilation during the airway closure was examined with EIT. Simultaneously four different artificial airway resistances were used to simulate airway obstructions. Results show that EIT in combination with the ROcc method is suitable for the detection of regional differences in ventilation during airway closure for all four artificial airway resistances. Although the sum of relative impedances at the end of the shutter maneuver are smaller (nearly -0.100 AU) for the airway resistances Ø 12.5 mm, Ø 10.5 mm and Ø 9.5 mm than for the smallest one with Ø 30.0 mm (~ -0.070 AU), the changes in impedance from the start to the end of the shutter maneuver differs only slightly between the four artificial airway resistances. All impedance changes are in the range of 0.100 to 0.130 AU. The combination of EIT and the ROcc method provides not only global parameters such as airway resistance under normal breathing conditions, but also results of regional ventilation, which could enable the identification of areas affected by airway obstructions. However, the obtained results indicate that EIT might be a useful tool in the diagnosis and follow-up of obstructive lung diseases.

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Altered K-complex morphology during sustained inspiratory airflow limitation is associated with next-day lapses in vigilance in obstructive sleep apnea

SLEEP ◽

10.1093/sleep/zsab010 ◽

2021 ◽

Author(s):

Ankit Parekh ◽

Korey Kam ◽

Anna E Mullins ◽

Bresne Castillo ◽

Asem Berkalieva ◽

...

Keyword(s):

Obstructive Sleep Apnea ◽

Sleep Apnea ◽

Spectral Characteristics ◽

Sleep Time ◽

Airflow Limitation ◽

Apnea Hypopnea Index ◽

Complex Morphology ◽

Obstructive Sleep ◽

Inspiratory Airflow Limitation ◽

Psychomotor Vigilance

Abstract Study Objectives Determine if changes in K-complexes associated with sustained inspiratory airflow limitation (SIFL) during N2 sleep are associated with next-day vigilance and objective sleepiness. Methods Data from thirty subjects with moderate-to-severe obstructive sleep apnea who completed three in-lab polysomnograms: diagnostic, on therapeutic continuous positive airway pressure (CPAP), and on suboptimal CPAP (4 cmH2O below optimal titrated CPAP level) were analyzed. Four 20-min psychomotor vigilance tests (PVT) were performed after each PSG, every 2 h. Changes in the proportion of spontaneous K-complexes and spectral characteristics surrounding K-complexes were evaluated for K-complexes associated with both delta (∆SWAK), alpha (∆αK) frequencies. Results Suboptimal CPAP induced SIFL (14.7 (20.9) vs 2.9 (9.2); %total sleep time, p < 0.001) with a small increase in apnea–hypopnea index (AHI3A: 6.5 (7.7) vs 1.9 (2.3); p < 0.01) versus optimal CPAP. K-complex density (num./min of stage N2) was higher on suboptimal CPAP (0.97 ± 0.7 vs 0.65±0.5, #/min, mean ± SD, p < 0.01) above and beyond the effect of age, sex, AHI3A, and duration of SIFL. A decrease in ∆SWAK with suboptimal CPAP was associated with increased PVT lapses and explained 17% of additional variance in PVT lapses. Within-night during suboptimal CPAP K-complexes appeared to alternate between promoting sleep and as arousal surrogates. Electroencephalographic changes were not associated with objective sleepiness. Conclusions Sustained inspiratory airflow limitation is associated with altered K-complex morphology including the increased occurrence of K-complexes with bursts of alpha as arousal surrogates. These findings suggest that sustained inspiratory flow limitation may be associated with nonvisible sleep fragmentation and contribute to increased lapses in vigilance.

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Brain-derived Neurotrophic Factor in Platelets and Airflow Limitation in Asthma

American Journal of Respiratory and Critical Care Medicine ◽

10.1164/rccm.200406-758oc ◽

2005 ◽

Vol 171 (2) ◽

pp. 115-120 ◽

Cited By ~ 75

Author(s):

Marek Lommatzsch ◽

Katharina Schloetcke ◽

Jens Klotz ◽

Katharina Schuhbaeck ◽

Doerte Zingler ◽

...

Keyword(s):

Neurotrophic Factor ◽

Brain Derived Neurotrophic Factor ◽

Airflow Limitation

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The effect of viscoelasticity in an airway closure model

Journal of Fluid Mechanics ◽

10.1017/jfm.2020.1162 ◽

2021 ◽

Vol 913 ◽

Author(s):

F. Romanò ◽

M. Muradoglu ◽

H. Fujioka ◽

J.B. Grotberg

Keyword(s):

Airway Closure ◽

Closure Model

Abstract

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COPD Guidelines in the Asia-Pacific Regions: Similarities and Differences

Diagnostics ◽

10.3390/diagnostics11071153 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1153

Author(s):

Shih-Lung Cheng ◽

Ching-Hsiung Lin

Keyword(s):

Chronic Obstructive Pulmonary Disease ◽

Pulmonary Disease ◽

Global Strategy ◽

Airflow Limitation ◽

Asia Pacific ◽

Pharmacologic Therapy ◽

Chronic Obstructive ◽

Obstructive Pulmonary Disease ◽

Country Level ◽

Similarities And Differences

Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease that is associated with significant morbidity and mortality, giving rise to an enormous social and economic burden. The Global Strategy for the Diagnosis, Management and Prevention of Chronic Obstructive Pulmonary Disease (GOLD) report is one of the most frequently used documents for managing COPD patients worldwide. A survey was conducted across country-level members of Asia-Pacific Society of Respiratory (APSR) for collecting an updated version of local COPD guidelines, which were implemented in each country. This is the first report to summarize the similarities and differences among the COPD guidelines across the Asia-Pacific region. The degree of airflow limitation, assessment of COPD severity, management, and pharmacologic therapy of stable COPD will be reviewed in this report.

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