Background: It has been proposed that the pH of airway lining fluid may regulate the fractional exhaled concentration of nitric oxide (FE NO ) in respiratory disease. Methods: FE NO , exhaled breath condensate (EBC) pH, and EBC concentrations of nitrite plus nitrate (NO 2 / NO 3 ) were compared in 12 subjects with stable asthma, 18 with stable cystic fibrosis (CF), and 15 healthy control subjects. Eight of the CF patients were studied on a separate occasion at the start of a pulmonary exacerbation. Results: FE NO was significantly greater in asthmatic subjects than in control subjects (mean 35 v 9 ppb, p,0.001). EBC pH, however, was similar in the asthmatic and control groups (median 5.82 v 6.08, p = 0.23). Levels of NO 2 /NO 3 were on average higher in EBC samples from asthmatic subjects, but the difference was not significant. In patients with stable CF both the FE NO (mean 4 ppb, p,0.001) and EBC pH (median 5.77, p = 0.003) were lower than in the control group. Levels of EBC NO 2 /NO 3 (median 29.9 mM; p = 0.002) in patients with stable CF, in contrast, were significantly higher than in control subjects. During CF exacerbations, EBC pH was further reduced (median 5.30, p = 0.017) but FE NO and NO 2 /NO 3 were unchanged.Conclusions: These findings demonstrate a dissociation between EBC pH and FE NO in inflammatory airways disease.

Background: A study was undertaken to investigate quality of life in asthma, defined by differing criteria, to see which may be most appropriate in epidemiological studies. Methods: The 426 adults were participants in the follow up phase of the European Community Respiratory Health Survey (ECRHS) in Melbourne. As part of the laboratory visit, participants completed the SF-36 quality of life questionnaire, a detailed respiratory questionnaire, and underwent lung function testing. Results: Both the physical component summary and the mental component summary scores were significantly worse in those with wheeze in the previous 12 months than in those without wheeze. Only the mental component summary score was significantly worse in those with current asthma than in those without. In contrast, in those with current asthma or bronchial hyperreactivity only, neither of the summary scales was significantly different between cases and controls. Conclusions: Quality of life is severely impaired in individuals with wheeze in the previous 12 months while individuals with current asthma or bronchial hyperreactivity alone did not appear to have significantly reduced quality of life. B ronchial hyperreactivity (BHR) to histamine or methacholine has been used as an objective physiological marker of asthma and, in combination with wheeze in the previous 12 months, has been used to define "current asthma" in epidemiological studies. It has been claimed that this definition discriminates a group with more severe asthma than subjective definitions based on self-reported asthma symptoms alone.1 2 However, subjective measures of asthma severity have been found to correlate much better with measures of quality of life (QoL) than objective physiological measures such as BHR and forced expiratory volume in 1 second (FEV 1 ).3 The purpose of this study was to examine the relationship between QoL and symptom based and physiological definitions of asthma in a community setting to determine which definition might be most appropriate. METHODSThe subjects were participants in the follow up phase of the ECRHS conducted in Melbourne in 1998/9. Full details of the original sampling protocol have been described elsewhere. 4 Participants completed the detailed ECRHS questionnaire, spirometric tests, and a methacholine challenge. QoL was evaluated by the short form (SF-36) health survey which was completed by participants upon arrival at the laboratory. All questionnaires were checked for missing data by one of the trained interviewers after completion. Only the physical component summary (PCS) score and the mental component summary (MCS) score are reported in this analysis which were calculated using the three step procedure recommended by the developer. 5 A total of 426 participants completed the methacholine challenge and were included in this analysis.Wheeze only was defined as a positive response to the question: "Have you had wheezing or whistling in your chest at any time in the last 12 months?".1 The ECRHS defined asthma as a positive r...

Among patients attending specialist cough clinics there is an excess of females, but the reason for this sex difference is unknown. We tested the hypothesis that the sensitivity of the cough reflex is greater in female compared with male patients with chronic cough. Inhalation cough challenges with capsaicin and citric acid were performed in a large group of patients with chronic cough. The concentrations of tussive agent causing two (C2) and five (C5) coughs were calculated. Measurements of capsaicin cough reflex sensitivity (median [interquartile range]) were significantly lower for female patients compared with male patients (C2: 1.9 [0.5 to 5.5] versus 5.3 [2.2 to 11.5] micro M, p = 0.0026; C5: 8.6 [2.2 to 34.0] versus 51.2 [7.2 to > 100] micro M, p = 0.0007). Similarly for citric acid challenge, values were significantly lower for female compared with male patients (C2: 53.5 [17.3 to 145.4] versus 118.1 [41.4 to 381.7] mM, p = 0.0064; C5: 300.0 [97.1 to > 1,000] versus 830.4 [300.0 to > 1,000] mM, p = 0.032). There were significant correlations between capsaicin and citric acid C2 values (r(s) = 0.54, p < 0.0001) and C5 values (r(s) = 0.57, p < 0.0001). These findings indicate a sex difference in cough sensitivity in patients with chronic cough, as previously reported in healthy volunteers. This may explain the female preponderance in cough clinics.