Pearls and pitfalls in the diagnosis of cough variant asthma.

Cough alone may sometimes be the sole presenting symptom of asthma. Patients experience cough without wheeze or shortness of breath and with normal baseline pulmonary function test results. These patients do, however, demonstrate bronchial hyperreactivity. They also respond to specific traditional asthma therapy. These patients are considered to have a specific asthma phenotype: cough variant asthma (CVA).In prospective studies of patients with chronic cough, an average of 25% have CVA. Patients have chronic cough, normal baseline pulmonary function tests, positive bronchial inhalation challenge results, and response to specific asthma therapy. What makes these patients cough is still unknown. The cough reflex is complex. The specific cause of cough in CVA may be similar to cough mechanisms seen in typical bronchial asthma.All therapies for typical bronchial asthma have been successful in controlling cough in patients with CVA. The overall prognosis of CVA is excellent, with most patients requiring chronic inhaled corticosteroid therapy.

The impact of different CPAP delivery approaches on nightly adherence and discontinuation rate in patients with obstructive sleep apnea.

STUDY OBJECTIVES: The impact of direct mail order sales of positive airway pressure (PAP) devices, accentuated by the coronavirus disease 2019 (COVID-19) pandemic, on PAP adherence in patients with obstructive sleep apnea remains unclear. In this study we compared the impact of different modes of continuous positive airway pressure delivery on adherence and daytime symptoms. We hypothesized that adherence would not be affected by remote PAP setup, aided by telehealth technology. METHODS: Three groups were studied: 1) standard group PAP setup (3-4 people); 2) direct home shipment of PAP, followed by telehealth interactions; 3) direct home shipment of PAP, during the COVID-19 pandemic where delivery choice was removed. Demographics, sleepiness, PAP data, and insurance information were also compared. RESULTS: A total of 666 patients were studied in 3 groups. 1) Standard group PAP setup had 225 patients and adherence with PAP (% of nights used more than 4 hours) was 65.3 ± 2.1%. 2) Direct home shipment of PAP group had 231 patients, and adherence was 54.2 ± 2.4%. 3) Direct mailed PAP units during the COVID-19 pandemic group had 210 patients, and adherence was 55.9 ± 2.5%. Adherence was lower in both groups receiving home shipments compared to those in groups in-center (analysis of variance, Tukey, P = .002). Discontinuation of PAP was less in the in-center group setup patients (χ2 = 10.938 P ≤ .001). CONCLUSIONS: Patients receiving direct home PAP shipments had lower adherence and were more likely to discontinue PAP compared to standard in-person setup. CITATION: Stanchina M, Lincoln J, Prenda S, et al. The impact of different CPAP delivery approaches on nightly adherence and discontinuation rate in patients with obstructive sleep apnea. J Clin Sleep Med. 2022;18(8):2023-2027.

Clinical Use of Loop Gain Measures to Determine Continuous Positive Airway Pressure Efficacy in Patients with Complex Sleep Apnea. A Pilot Study.

RATIONALE: Measures of unstable ventilatory control (loop gain) can be obtained directly from the periodic breathing duty ratio on polysomnography in patients with Cheyne-Stokes respiration/central sleep apnea and can predict the efficacy of continuous positive airway pressure (CPAP) therapy. OBJECTIVES: In this pilot study, we aimed to determine if this measure could also be applied to patients with complex sleep apnea (predominant obstructive sleep apnea, with worsening or emergent central apneas on CPAP). We hypothesized that loop gain was higher in patients whose central events persisted 1 month later despite CPAP treatment versus those whose events resolved over time. METHODS: We calculated the duty ratio of the periodic central apneas remaining on the CPAP titration (or second half of the split night) while patients were on optimal CPAP with the airway open (obstructive apnea index < 1/h). Loop gain was calculated by the formula: LG = 2π/[(2πDR - sin(2πDR)]. Patients were followed on CPAP for 1 month. Post-treatment apnea-hypopnea index and compliance data were recorded from smart cards. MEASUREMENTS AND MAIN RESULTS: Thirty-two patients with complex sleep apnea were identified, and 17 patients had full data sets. Eight patients continued to have a total of more than five events per hour (11.8 ± 0.5/h) (nonresponders). The remaining nine patients had an apnea-hypopnea index less than 5/h (2.2 ± 0.4/h) (responders). Loop gain was higher in the nonresponders versus responders (2.0 ± 0.1 vs. 1.7 ± 0.2, P = 0.026). Loop gain and the residual apnea-hypopnea index 1 month after CPAP were associated (r = 0.48, P = 0.02). CPAP compliance was similar between groups. CONCLUSIONS: In this pilot study, loop gain was higher for patients with complex sleep apnea in whom central apneas persisted after 1 month of CPAP therapy (nonresponders). Loop gain measurement may enable an a priori determination of those who need alternative modes of positive airway pressure.

Impact of CPAP use and age on mortality in patients with combined COPD and obstructive sleep apnea: the overlap syndrome.

BACKGROUND: The overlap syndrome, defined by concurrent existence of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA), is associated with poor outcomes. From a large outpatient cohort we aimed to define better the risk factors for increased mortality in the overlap syndrome and hypothesized that CPAP adherence would be associated with improved survival in patients with overlap syndrome. METHODS: A post hoc analysis from an outpatient database of 10,272 patients from 2007-2010, identified 3,396 patients which were classified in 6 groups; patients both alive or deceased, with the known diagnosis of COPD, OSA, and the overlap of COPD plus OSA. Information regarding their gender, age, pulmonary function, obstructive sleep apnea parameters, and CPAP compliance was collected. A multivariate Cox proportional hazards model was generated for the determinants of mortality. RESULTS: 1,112 COPD patients and 2,284 OSA patients were identified by diagnostic coding and then comprehensive chart review. Of these, 227 patients were identified with the overlap syndrome. From this group, 17 patients (7.4%) died. Multivariate analysis revealed hours of CPAP use and age as independent predictors of mortality (HR 0.71 and 1.14, p < 0.001, 0.002). Greater time on CPAP was associated with reduced mortality; although age did not correlate with CPAP use (p = 0.2), mean age of those with CPAP use < 2 hours per night was significantly higher than those using CPAP > 2 hours per night. CONCLUSIONS: From this observational cohort, mortality in the overlap syndrome is impacted by CPAP use. Age is also an independent factor which has a negative association with survival and CPAP usage.