PHYSIOLOGICAL PERSPECTIVES OF THERAPY IN BRONCHIAL HYPERREACTIVITY

Purpose: This paper reviews the literature on the aetiology and therap y of bronchial hyperreactivity: to describe the underlying pathophysio logy, identify patients at risk and update knowledge on nari and exist ing therapies. Source: Information was obtained from monograms on New Drugs for Asthma, Respiratory Medicine: recent advances, Agents and Ac tions Supplements, Pulmonary Pharmacology, Anesth Analg, the European Journal Of Respiration and a Medline literature search. Principal find ings: Reduced airway calibre, increased bronchial contractility altere d permeability of the bronchial mucosa, humoral and cellular mediators , and dysfunctional neural regulation are critical factors for bronchi al hyperreactivity, a characteristic feature of hyperreactive airways which results in bronchoconstriction after exposure to varied stimuli. Preoperative anaesthetic considerations in these patients include FEV (1) and PEFR testing to assess the severity and for optimal control of the condition. Bronchospasm causing hypoxaemia is the major intraoper ative problem anticipated in these patients. Current therapeutic manag ement of bronchoconstriction focusses on the beta(2) agonists, theophy lline and steroids. Besides relaxing the airway smooth muscle these ag ents are all capable of altering bronchial inflammatory responses. Fut ure developments of therapy are directed towards the inflammatory comp onents of the disease. Conclusion: This review has presented backgroun d information on physiological mechanisms of smooth muscle contractili ty, pathophysiological alterations of bronchial contractility and the pharmacological basis of therapy in bronchoconstrictive disease. Infor mation is presented to enable the prompt arrest and reversal of airway constriction, and to maintain prophylactic treatment during the perio perative period Intraoperative bronchospasm is managed by adequate oxy genation and reversal of bronchoconstriction.