No abstract

We have evaluated the properties of capsaicin as a selective cough-inducing agent in healthy human subjects. Despite frequent coughing, the subjects could inhale repeated breaths of capsaicin aerosol during 60 s without difficulty. Cough started immediately on inhalation and was most intense during the first 30 s. Cough always disappeared promptly when the capsaicin inhalation was terminated. The cough response was well reproducible and concentration-dependent up to 10 microM; at higher concentrations there was a distinct plateau of the cough response. Specific airway conductance was not changed 3 min after 50 microM capsaicin. Capsaicin (> or = 10 microM) had a burning taste, but there were no visual signs of pharyngitis or laryngitis. Citric acid (nebulized solutions 0.125 to 32%) had a choking effect and could be administered only as single breaths. There was no correlation between the cough response to citric acid and to capsaicin. Inhaled lidocaine (20 and 80 mg from nebulized solutions) caused a dose-dependent inhibition of capsaicin-induced cough. Lidocaine suppressed citric acid-induced cough as effectively as capsaicin-induced cough. In conclusion, we have characterized capsaicin-induced cough and demonstrated that it can be a useful tool in the study of cough reactivity and for evaluation of antitussive agents in humans. Capsaicin may be complementary to citric acid and may offer experimental advantages over this traditional tussive stimulus.

Home mechanical ventilation (HMV) is increasingly used as a therapeutic option to patients with symptomatic chronic hypoventilation. There is, however, a paucity of solid data on factors that could affect prognosis in patients on home ventilation. In the present study, our aim was to study several factors in these patients with potential influence on survival. We examined 1526 adult patients from a nationwide HMV register to which data had been reported prospectively for 10 years. The patients constituted a broad diagnostic spectrum and the primary outcome in this study was death. We found by far the poorest survival rate in the ALS patients with only 5% alive after 5 years. Among the other patient groups the survival pattern was more uniform and the scoliosis, polio and Pickwick patients presented the best survival rate, after 5 years being around 75%. No factors were associated with a greater hazard for death in the ALS patients; in the non-ALS patients, however, negative predictors for survival were age, concomitant use of oxygen therapy, tracheostomy ventilation and start of ventilatory support in an acute clinical setting. Center size or county specific home ventilation treatment prevalence did not affect survival. In conclusion, in a large material of patients on HMV we found by far the poorest survival in the ALS patients. In the non-ALS patients a number of patient-related factors affected survival, while the size of the treating center or the regional treatment prevalence did not.

We examined local differences in prescription pattern of home mechanical ventilation (HMV) within the homogenous health care system in Sweden. We used 6 years prospective data from the national HMV Register covering the entire Swedish HMV patient population (more than 1000 patients). The treatment prevalence of HMV in Sweden, January 1, 1996 was 6.2/100,000 and January 1, 2002 10.5/100,000 with a steady increase each year in all counties. The differences between leading and non-leading counties showed a tendency to diminish due to an increasing prescription rate in the non-leading counties. During the 6 years, the proportion of Pickwickian patients increased significantly in the country as a whole, but remained considerably and significantly higher in the leading counties, in spite of similar and temporally stable prescription criteria. Even if the evident dissimilarities in treatment prevalence may be levelling out, it will most probably do so at a level as high as or higher than today's top level of more than 20/100,000 since we found that HMV therapy was well founded also in the counties with the highest prescription rates and that the prescription rate of the non-leading counties was approaching the level of the leading counties.

Measurements of health-related quality of life (HRQL) have not been reported in patients with chronic alveolar hypoventilation (CAH) before starting home mechanical ventilation. The purpose of this study was to investigate quality of life in a population of such patients.Forty-four consecutive patients with CAH due to previous polio, scoliosis, healed pulmonary tuberculosis or neuromuscular disease answered a battery of condition specific and generic (Sickness Impact Profile, Hospital Anxiety and Depression scale, Mood Adjective Check List) self-report questionnaires. Spirometry, arterial blood gases and overnight oxygen saturation were measured.Patients with untreated CAH had significantly impaired HRQL compared to historical data from a healthy reference population. Sleep-related problems were frequent. Age, underlying disease, and standard bicarbonate correlated significantly with HRQL measures, albeit with modest levels of explained variance (8-37%).Patients with chronic alveolar hypoventilation due to neuromuscular or restrictive chest wall disorders had severely impaired health-related quality of life. Age, the underlying disease and severity of hypoventilation are each related to the health-related quality of life decrements. Health-related quality of life measurements add important information to traditional clinical observations.