Study of methacholine positivity in patients with chronic cough at Masih Daneshvari hospital, Tehran, 2007-08

While airways reactivity is among the characteristics of asthma, is not considered a sufficient condition diagnostically and the methacholine challenge is a non-specific diagnostic aid in cases of chronic cough and reactive airways disease. The aim of this cross-sectional study was to determine the metacholine response positivity and diagnosis of asthma in patients with chronic cough presenting to a hospital in Tehran during 2007 and 2008. Of 101 patients with chronic cough [with no history of sinusitis, recent pulmonary infection, bronchitis, gasteroesophageal reflux or underlying pulmonary conditions], 51.5% showed reactive airways disease to the methacholine test, 40.6% were unreactive and 7.9% were indeterminate. A positive methacholine challenge test was positively correlated with new wheezing. Although the methacholine challenge test is not a primary test for evaluating chronic cough, if no other reason for chronic cough is found, it may be a guiding test for asthma

Effect of salbutamol on pulmonary responsiveness in chronic pulmonary allergic inflammation in guinea pigs

Beta-2-agonists have been widely used by asthmatic subjects to relieve their obstructive symptoms. However, there are reports that continuous use could lead to loss of bronchial protection and exacerbation of asthma symptoms. We evaluated the effect of two regimens of salbutamol administration (twice and five times a week) in a model of chronic airway inflammation in male Hartley guinea pigs (protocol starting weight: 286 ± 30 g) induced by repeated exposures to aerosols of ovalbumin (OVA). After sensitization, guinea pigs were exposed to aerosols of 0.1 mg/ml salbutamol solution twice a week (OVA + S2x, N = 7) or five times a week (OVA + S5x, N = 8). We studied allergen-specific (OVA inhalation time) and -nonspecific (response to methacholine) respiratory system responsiveness. Seventy-two hours after the last OVA challenge, guinea pigs were anesthetized and tracheostomized, respiratory system resistance and elastance were measured and a dose-response curve to inhaled methacholine chloride was obtained. Specific IgG1 was also quantified by the passive cutaneous anaphylactic technique. OVA-sensitized guinea pigs (N = 8) showed reduction of the time of OVA exposure before the onset of respiratory distress, at the 5th, 6th and 7th exposures (P < 0.001). The OVA + S2x group (but not the OVA + S5x group) showed a significant increase in OVA inhalation time. There were no significant differences in pulmonary responsiveness to methacholine among the experimental groups. OVA + S2x (but not OVA + S5x) animals showed a decrease in the levels of IgG1-specific anaphylactic antibodies compared to the OVA group (P < 0.05). Our results suggest that, in this experimental model, frequent administration of ß2-agonists results in a loss of some of their protective effects against the allergen.

Respuesta bronquial a metacolina en trabajadores expuestos crónicamente a anhídrido sulfuroso / Bronchial response to methacoline in workers chronically exposed to sulfur dioxide

Con el propósito de evaluar el efecto de la inhalación crónica de concentraciones altas de SO2 sobre la frecuencia de síntomas respiratorios, la función pulmonar y la reactividad bronquial, se estudió a 23 trabajadores de una fundición de cobre expuestos a SO2. Como grupo control se estudió 14 funcionarios administrativos de la misma fundición, no expuestos a SO2 y 10 trabajadores del hospital de LLay-LLay localidad cercana a la fundición sin SO2 en el ambiente. En todos los sujetos se evaluó la presencia de síntomas respiratorios mediante una encuesta, se determinó la capacidad vital y el VEF1 y se realizó una curva dosis-respuesta a metacolina en la que se midió la respuesta máxima (M), la dosis que produce el 50 por ciento de la respuesta máxima (ED50) y la concentración que produce la caida del 20 porciento del VEF1 (PC20). No se encontró diferencias en la frecuencia de síntomas respiratorios entre los 3 grupos estudiados. Los valores espirométricos fueron normales y no se encontró diferencias significativas entre los grupos. La M fue de 13.9ñ7.9 porciento en los trabajadores expuestos, 11.9ñ8.7 porciento en los administrativos y 14ñ11.6 por ciento en los trabajadores de LLay -LLay. La ED50 fue del 0.29ñ0.5 mM; 0.28ñ0.27 mM y 0.15ñ0.16 mM respectivamente. No se encontró relación entre la magnitud y los índices funcionales medidos. Los resultados sugieren que la exposición crónica a SO2 en el ambiente laboral no produce alteraciones en la reactividad bronquial ni aumenta los síntomas respiratorios