Effect of increasing respiratory rate on airway resistance and reactance in COPD patients.

BACKGROUND AND OBJECTIVE: Airway resistance and reactance measured by forced oscillometry have been used to measure the severity of airway obstruction in chronic obstructive pulmonary disease (COPD) patients. The aims of this study were to assess the effects of tachypnoea on airway resistance and reactance and to correlate these with the severity of dyspnoea. We also evaluated the effects of short-acting ß2-agonist (SABA) on these measurements. METHODS: Airway resistance and reactance were measured with an impulse oscillation system (IOS) in 20 COPD and 10 control participants during resting respiration and metronome-paced breathing at 20, 30 and 40 tidal breaths/min. The same measurements were made for COPD patients after SABA inhalation. Dyspnoea was evaluated using the modified Medical Research Council (MRC) scale. RESULTS: In patients with COPD, higher respiratory rates increased expiratory and inspiratory resistance at 5 Hz (R5), the difference in respiratory resistance at 5 Hz and 20 Hz (R5-R20), resonant frequency and decreased expiratory reactance. The decreases in expiratory reactance from 20 to 40 tidal breaths/min were significantly correlated with MRC scores. SABA inhalation significantly reduced the effect of increased respiratory rate on the reactance measurements. CONCLUSIONS: Characteristic changes in IOS measurements, particularly expiratory reactance, induced by increased respiratory rates, were correlated with severity of dyspnoea in COPD patients during their daily lives. IOS and paced breathing may be useful for assessing breathlessness in COPD.

Pediatric pulmonology year in review 2023: Physiology.

Application of the principles of pulmonary physiology and lung development to the care and management of respiratory disease in children is a distinguishing feature of pediatric pulmonology. In 2023, this was evident in numerous publications in Pediatric Pulmonology and other journals. This review will highlight some of the papers in this area.

Pediatric pulmonology year in review 2021 and 2022: Physiology.

Pulmonary physiology is a core element of pediatric pulmonology care and research. This article reviews some of the notable publications in physiology that were published in Pediatric Pulmonology in 2021 and 2022.

Respiratory morbidities and lung function abnormalities in survivors of Bhopal Gas Disaster: A cross-sectional study.

BACKGROUND: Respiratory morbidities remained significant for the last four decades among the survivors of the Bhopal gas disaster. We hypothesized that lung function abnormalities, especially small airway dysfunctions, were responsible for the ongoing respiratory morbidities. METHODS: We conducted a cross-sectional study between 2018 and 2020 in the severely exposed cohort of the Bhopal gas disaster. A standardized questionnaire was used to record their respiratory symptoms. The forced oscillometry (FOT) and spirometry were utilized for assessing lung functions. Univariate and multivariate logistic regression analyses were used to examine the association. RESULTS: Of 916 enrolled individuals (men: 442, mean age: 55.2 ± 12.3 years), 558 participated in lung function assessments. Breathlessness was the most common complaint (71.7%), followed by cough (15.1%). The R5 > upper limit of normal (ULN), R5-19 > ULN, and X5 < lower limit of normal (LLN) were observed in 29.3%, 23.3%, and 21.2% participants, respectively. Normal, obstructive, and restrictive spirometry was observed in 46.2%, 26.1%, and 27.7%, participants, respectively. FOT parameters were abnormal in 25.3% individuals with normal spirometry. Individuals with obstructive spirometry had the highest risk of having abnormal FOT parameters (adjusted odds ratio [adj OR]:3.93, 95% confidence interval [CI]: 2.24-6.89). Breathlessness showed a significant association with abnormal R5 (adj OR: 1.81; 95% CI: 1.13-2.91) and obstructive spirometry (adj OR: 2.26; 95% CI: 1.29-3.95). CONCLUSIONS: Assessment of small airway functions along with spirometry are useful to identify complex lung function abnormalities in cases of toxic inhalation.

Within-session reproducibility of forced oscillometry.

BACKGROUND: The forced oscillation technique (FOT) provides detailed information about the mechanics of the respiratory system, while requiring minimal co-operation by the patient. FOT may be abnormal in subjects with normal spirometry and appears to be more closely related to airway symptoms. It is, therefore, attractive in epidemiological studies, where a large number of different examinations are made in each subjects in a short period of time. Current technical standards recommend the mean of three consecutive measurements to be used, but there is limited information regarding within-session variability of FOT measurements. OBJECTIVE: The purpose of this study was to examine the within-session variability in FOT measurements in a large, population-based sample. METHODS: We performed three consecutive FOT measurements in 700 subjects using the impulse oscillometry system. The first measurement was compared to the mean of three measurements for resistance at 5 and 20 Hz (R5 and R20, respectively), R5-R20, reactance at 5 Hz (X5) and resonant frequency (fres ). RESULTS: The differences between the first and the mean of three measurements (median, interquartile range) were minimal, for example 0.002, -0.008 to 0.014 kPa L-1  s for R5 and -0.001, -0.008 to 0.005 kPa L-1  s for X5. Findings were numerically similar for men and women as well as for subjects with and without airflow obstruction at spirometry. CONCLUSIONS: We conclude that, whereas in clinical situations, three FOT measurements are to be preferred, a single measurement may suffice in epidemiological studies.

Pediatric pulmonology year in review 2020: Physiology.

Pulmonary physiology is a core element of pediatric pulmonology care and research. This article reviews some of the notable publications in physiology that were published in Pediatric Pulmonology in 2020.

Altered lung function at mid-adulthood in mice following neonatal exposure to hyperoxia.

Infants born very preterm are usually exposed to high oxygen concentrations but this may impair lung function in survivors in later life. However, the precise changes involved are poorly understood. We determined how neonatal hyperoxia alters lung function at mid-adulthood in mice. Neonatal C57BL/6J mice inhaled 65% oxygen (HE group) from birth for 7 days. They then breathed room air until 11 months of age (P11mo); these mice experienced growth restriction. Controls breathed only room air. To exclude the effects of growth restriction, a group of dams was rotated between hyperoxia and normoxia during the exposure period (HE+DR group). Lung function was measured at P11mo. HE mice had increased inspiratory capacity, work of breathing and tissue damping. HE+DR mice had further increases in inspiratory capacity and work of breathing, and reduced FEV100/FVC. Total lung capacity was increased in HE+DR males. HE males had elevated responses to methacholine. Neonatal hyperoxia alters lung function at mid-adulthood, especially in males.