Monitoring Adult Subglottic Stenosis With Spirometry and Dyspnea Index: A Novel Approach

Objective The aim was to examine the correlations among the anatomic Cotton-Myer classification, pulmonary function tests (PFTs), and patient-perceived dyspnea or dysphonia in patients with subglottic stenosis and identify measurements accurately reflecting treatment effects. Study Design Prospective cohort study. Setting Tertiary referral center. Method Fifty-two adults receiving endoscopic treatment for isolated subglottic stenosis were consecutively included. Correlations were calculated among the preoperative Cotton-Myer scale, PFTs, the Dyspnea Index (DI), and the Voice Handicap Index. Receiver operating characteristic curves were determined for PFT, DI, and Voice Handicap Index pre- and postoperative measurements. Results The Cotton-Myer classification correlated weakly with peak expiratory flow ( r = −0.35, P = .012), expiratory disproportion index ( r = 0.32, P = .022), peak inspiratory flow ( r = −0.32, P = .022), and total peak flow ( r = −0.36, P = .01). The DI showed an excellent area under the curve (0.99, P < .001), and among PFTs, the expiratory disproportion index demonstrated the best area under the curve (0.89, P < .001), followed by total peak flow (0.88, P < .001), peak expiratory flow (0.87, P < .001), and peak inspiratory flow (0.84, P < .001). Patients treated endoscopically with balloon dilatation showed a 53% decrease in expiratory disproportion index (95% CI, 41%-66%; P < .001) and a 37% improvement in peak expiratory flow (95% CI, 31%-43%; P < .001). Conclusion Expiratory disproportion index or peak expiratory flow combined with DI was a feasible measurement for the monitoring of adult subglottic stenosis. The percentage deterioration of peak expiratory flow and increase in expiratory disproportion index correlated significantly with a proportional percentage increase in DI.

Quantification of Airway Conductance from Non-invasive Ventilatory Drive in Patients with Sleep Apnea

Upper airway conductance, the ratio of inspiratory airflow to inspiratory effort, quantifies the degree of airway obstruction in hypopneas observed in sleep apnea. We evaluated the ratio of ventilation to non-invasive ventilatory drive as a surrogate of conductance. Further, we developed and tested a refinement of non-invasive drive to incorporate the interactions of inspiratory flow, pressure, and drive in order to better estimate conductance. Hypopneas were compiled from existing polysomnography studies with esophageal catheterization in 18 patients with known or suspected sleep apnea, totaling 1517 hypopneas during NREM sleep. For each hypopnea, reference-standard conductance was calculated as the ratio of peak inspiratory flow to esophageal pressure change during inspiration. Ventilatory drive was calculated using the algorithm developed by Terrill et al and then mathematically modified according to the presence or absence of flow limitation in order to non-invasively estimate esophageal pressure. The ratio of ventilation to ventilatory drive and the ratio of peak inspiratory flow to estimated esophageal pressure were each compared to the reference standard for all hypopneas and for median values from individual patients. Hypopnea ventilation:drive ratios were of limited correlation with the reference standard (R2 = 0.17, individual hypopneas; R2 = 0.03, median patient values). Modification of drive to estimated pressure yielded estimated conductance, which strongly correlated with reference standard conductance (R2 = 0.49, individual hypopneas; R2 = 0.77, median patient values­). We conclude that the severity of airway obstruction during hypopneas may be estimated from non-invasive drive by accounting for mechanical effects of flow on pressure.

The Relationship Between Peak Inspiratory Flow and Hand Grip Strength Measurement in Men with Mild Chronic Obstructive Pulmonary Disease

Backgrounds: Chronic obstructive pulmonary disease (COPD) decreases quality of life and muscular strength. Inspiratory flow is important for inhalants in the bronchi but is complicated to measure in routine practice. We hypothesized that hand grip strength (HGS) would correlate with inhalation rate in patients with mild COPD.Methods: The COPD patients were recruited at the St. Marianna University School of Medicine, Yokohama Seibu Hospital, from 2015 to 2018. We measured peak inspiratory flow (PIF) through an In-Check flow meter attached with Diskus [PIF(D)] and Turbuhaler [PIF(T)] inhalers. The 6-minute walking test (6MWT), and the fraction of exhaled nitric oxide (FENO), spirometry, HGS, or forced oscillation technique (FOT) parameters were measured.Results: Forty-four subjects were enrolled. All were men, with a mean age (± SD) of 77.8 ± 9.36 years. Thirty-nine patients had mild COPD. PIF(D) was 110 (80, 140) L/min (median, interquartile range), PIF(T) was 80 (70, 90) L/min, and HGS was 28.7 (13.8, 43.6) kgf. PIF(D) and PIF(T) were significantly correlated (r = 0.443, p = 0.003). PIF(D) was significantly correlated with age (r = − 0.327, p = 0.030) and HGS (r = 0.326, p = 0.031). PIF(T) was significantly correlated with age (r = − 0.328, p = 0.030), FVC (r = 0.351, p = 0.019), 6MWT distance (r = 0.392, p = 0.011), and HGS (r = 0.328, p = 0.030).Conclusion: HGS might be more useful for predicting PIF than other parameters. Also, elderly COPD patients need to be taught inhaled methods carefully.

Peak-Inspiratory-Flow-Rate Guided Inhalation Therapy Reduce Severe Exacerbation of COPD

Optimal peak inspiratory flow rate (PIFR) is crucial for inhalation therapy in patients with chronic obstructive pulmonary disease (COPD). However, little is known about the impact of PIFR-guided inhalation therapy on the clinical outcomes among patients with varying severities of COPD. A PIFR-guided inhalation therapy, including PIFR assessment and PIFR-guided inhaler education, was introduced in a pay-for-performance COPD management program in National Taiwan University Hospital. Among 383 COPD patients, there was significant reduction in incidence of severe acute exacerbation in the PIFR-guided inhalation therapy (PIFR group) than conventional inhaler education (control group) (11.9 vs. 21.1%, p = 0.019) during one-year follow-up. A multivariable Cox’s proportional-hazards analysis revealed that the PIFR-guided inhalation therapy was a significant, independent factor associated with the reduced risk of severe exacerbation (adjusted hazard ratio = 0.49, 95% confidence interval, 0.28–0.84, p = 0.011). Subgroup analysis found PIFR-guided inhalation therapy was more beneficial to patients with older age, short body stature, COPD stage 1&amp;2, group C&amp;D (frequent exacerbation phenotype), and using multiple inhalers. This study showed the PIFR-guided inhalation therapy significantly reduced the incidence of severe acute exacerbation than conventional inhaler education in patients with COPD. Careful PIFR-assessment and education would be crucial in the management of COPD.