Small Airways Dysfunction and Bronchial Hyper-Responsiveness in Cough Variant Asthma.

BACKGROUND: Cough variant asthma (CVA) is one kind of atypical asthma. The study was to compare spirometric parameters of small airways and the degree of bronchial hyper-responsiveness (BHR) between CVA and classic asthma (CA), and examine the relationship between BHR and small airways to determine the accuracy of these markers as indicators of CVA. METHODS: A total of 825 asthmatic patients were screened for the study, and 614 were included. All patients performed spirometry and underwent a bronchial challenge with methacholine. RESULTS: The number of small airways dysfunctions in the CVA group was less than those of the CA group with MMEF% predicted (70% vs 80.91%, P=0.002) and FEF50% predicted (62.71% vs 73.5%, P=0.004). The degree of small airways dysfunction was less in the CVA group compared with the CA group (P<0.001). Significant positive correlations were observed between the FEV1 level below 20% of the baseline value (PD20) and MMEF% predicted (r=0.282, P<0.001), FEF50% predicted (r=0.2522, P<0.001), and FEF75% predicted (r=0.2504, P<0.001) in patients with CVA. The area under curve (AUC) of MMEF, FEF50, and FEF75 (% predicted) was 0.615, 0.621, and 0.606, respectively. In addition, 0.17 mcg of PD20 was the best diagnostic value for CVA, with an AUC of 0.582 (P=0.001). CONCLUSION: Small airway dysfunction is milder in CVA. The value of BHR combined with small airways in CVA prediction, which was significant, but not enough to be clinically useful.

[Comparison of manual versus automatic titration in pressure determination for long-term therapy of continuous positive airway pressure in patients with obstructive sleep apnea hypopnea syndrome].

OBJECTIVE: To compare the continuous positive airway pressure (CPAP) of automatic titration with that of manual titration. METHODS: A total of 58 patients with obstructive sleep apnea and hypopnea syndrome (OSAHS) diagnosed by overnight polysomnography at sleep center of First Affiliated Hospital, Guangzhou Medical University were studied between December 2010 and December 2012. Manual titration was performed under full polysmnography and auto-titration at home for 3-7 nights. RESULTS: There were 52 males and 6 females with an age range of (48 ± 11) years. CPAP pressure titrated by automatic device (10.0 ± 2.2) cm H2O (1 cm H2O = 0.098 kPa) was significantly higher than that titrated manually (7.5 ± 1.5) cm H2O (P = 0.000). Apnea-hyponea index decreased significantly from (54.0 ± 21.0) events/h pre-treatment to (3.8 ± 2.5) events/h post-treatment under manual titration (P < 0.01). CONCLUSIONS: CPAP pressure titrated by automatic device is usually higher than that titrated manually. Manual titration should be performed if a patient can not tolerate the CPAP pressure titrated by an automatic device.