No abstract

Six patients with chronic cough, without history of dyspnea or wheezing, had normal base-line spirometry but hyper-reactive airways, as demonstrated with methacholine. Maintenance therapy with bronchodilators promptly eliminated the cough in all patients. Three to 12 months later therapy was discontinued for three days, cough returned, and detailed pulmonary-function studies were carried out. Again, base-line values were normal, but after methacholine one-second forced expiratory volume decreased an average of 40 per cent in the patients as compared to 30 per cent in normal controls (P less than 0.001). The point of identical flow was increased by methacholine to 43.5 per cent of vital capacity in the patients, as compared to 6 per cent in normal controls (P less than 0.001), and the alveolar plateau was 4.8 deltaN2 per liter, as compared to 1.4 in normal controls (P less than 0.01). Specific airway conductance was lowered in patients and controls, but the post-methacholine value was significantly lower in the patients. On the basis of their persistently hyper-reactive airways, inducible diffuse airway bronchoconstriction and excellent response to bronchodilator therapy, these patients appear to have a variant form of asthma in which the only presenting symptom is cough.

chronic cough are presented in algorithmic form (Fig 1-3). Guidelines with algorithms for evaluating chronic cough in pediatric patients < 15 years of age are presented in the section entitled "Guidelines for Evaluating Chronic Cough in Pediatrics" 2,4 [Fig 4, 5]. For a full discussion on how to use the algorithms, please refer to these sections. Summary and Recommendations Recommendations for each section of these guidelines are listed under their respective section titles. For an in-depth discussion or clarification of each recommendation, readers are encouraged to read the specific section in question in its entirety. Methodology and Grading of the Evidence for the Diagnosis and Management of Cough 5 • The recommendations were graded, by consensus by the panel, using the American College of Chest Physicians Health and Science Policy Grading System, which is based on the following two components: quality of evidence; and the net benefit of the diagnostic and therapeutic procedure. • The quality of evidence is rated according to the study design and strength of other methodologies used in the included studies.