Factors Influencing Intrapulmonary Airway Calibre During Anaesthesia

Perioperative management of the asthmatic patient

“…32"33 Mechanisms to account for this include inhibition of vagal pathways, direct relaxation of airway smooth muscle and increases in endogenous catecholamines which relax the airway via 132-adrenoceptors on airway smooth muscle. 34 Studies showing direct relaxing effects of ketamine on smooth muscle used concentrations of ketamine greater than we usually use clinically. 35'36 Administration of the drug by aerosol could allow enough ketamine to reach the airway smooth muscle and at the same time decrease undesirable side-effects.…”

“…34 The action of anaesthetics on airway reflexes has been studied for decades and the ability of halothane, 39"4~ cyclopropane, 39 and ether 42 to block a wide variety of airway reflexes has been well established. More recently, Vetterman et al 42 showed that isoflurane and enflurane were as effective as halothane at equivalent MAC multiples in dogs at antagonizing vagally mediated bronchoconstriction.…”

“…32,33 Les m6canismes qui les expliquent comprennent I'inhibition des fibres du vague, un effet direct de relaxation sur les muscles lisses des voies a6riennes et I'augmentation de cath6colamines endog6nes, qui elles-m~mes rel:~chent les voies a6riennes via les IB2-r6cepteurs des muscles lisses de l'arbre bronchique. 34 Dans les 6tudes qui montraient les effets directs de la k6tamine sur le muscle lisse, les concentrations de k6tamine utilis6e 6taient plus importantes que celles employees en clinique. 35"36 L'administration de la k6ta-mine en a6rosol permettait h suffisamment de k6tamine de se rendre aux muscles lisses bronchiques et en m~me temps amenait une diminution des effets secondaires.…”

Cellular mechanisms of airway smooth muscle relaxant effects of anesthetic agents

“…It is important for anesthesiologists to know how anesthetic agents that are used clinically can affect airway smooth muscle tone, since anesthesia is often performed on patients with airway hyperreactivity, such as patients with asthma or emphysema. Hirshman and Bergman [2] first reviewed the factors influencing intrapulmonary airway caliber during anesthesia. Many studies have since been carried out on direct and indirect effects of anesthetic agents on airway smooth muscle tone using appropriate and sophisticated techniques (Fig.…”

Role of Endogenous Histamine in Altered Lung Mechanics in Rabbits

“…The resulting hypoxia can be observed during the induction and maintenance of anesthesia and also during recovery. 1,2 Various mechanisms are responsible for these adverse effects on the lung mechanics, such as the stimulation of irritant receptors by tracheal intubation 2 or histamine liberation induced by the administration of anesthetic agents. [3][4][5][6][7][8] Among the anesthetic agents, the myorelaxants are the most potent histamine-releasing drugs, 4 -8 and mivacurium has been demonstrated to elevate the plasma histamine level significantly (more than threefold).…”