title: A new spirometric parameter in clinical pharmacology.
abstract: Several functional parameters can be used to define respiratory dysfunctions. Many of these variables provide specific information about particular physiopathologic phenomena, but they seldom provide a general overview of the ventilatory function. Nevertheless, both pharmacologic and epidemiologic research need functional parameters that precisely specify the respiratory defect. The new parameter we discuss takes into account the variations in volumes as related to flow variations: it is the product of two traditional spirometric parameters (FEV1 X MMEF). This value gives information on the patient's capacity to exhale air from the lungs for a fixed variation of intrathoracic pressure as well as data on the acceleration pattern of the expired volume in 1 s, hence the name, acceleration index (AI). AI was used to predict bronchodilation in two groups of patients with severe airway flow limitations. On the basis of our findings three conclusions can be drawn. This new spirometric parameter provides an inexpensive and rapid means of obtaining a highly sensitive definition of the patient's respiratory dysfunction which is useful in screening patients. Applied to patients with severe airways obstruction, AI can be used to immediately predict the reversibility of air flow limitation and then to define the limits of the activity of bronchodilators. Finally, a basal value of AI below 1.000 l/s-1 indicates the probable irreversibility of the airways obstruction, regardless of drug or route of administration. Such cases suggest a prevailing picture of emphysema rather than reversible bronchospasm.
mesh_terms: D001784:Blood Gas Analysis; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000503:physiopathology; D008297:Male; D008450:Maximal Midexpiratory Flow Rate; D008875:Middle Aged; D013147:Spirometry / Q000379:methods*; D013806:Theophylline / Q000627:therapeutic use; D014213:Tretoquinol / Q000627:therapeutic use
chemical_list: D013806:Theophylline; D014213:Tretoquinol