title: Effects of an opioid on respiratory movements and expiratory activity in humans during isoflurane anaesthesia.
abstract: Opioids increase abdominal muscle activity during anaesthesia. We proposed that opioid activity during anaesthesia would change chest wall size and movement, and contribute to ventilation. Using an optical system to measure chest wall volume, we studied 10 patients during isoflurane anaesthesia, first under the influence of an opioid and then after reversal with naloxone. Measurements were made during quiet breathing and with carbon dioxide stimulation. Airway occlusion pressure was measured to assess inspiratory and expiratory muscle activity. Chest wall volume decreased with the onset of spontaneous breathing, and decreased further when breathing was stimulated by carbon dioxide. Reversal of opioid activity increased chest wall volume. Breathing movements were predominantly abdominal. Opioid action affected the timing and amplitude of breathing but the pattern of abdominal movement was not affected. Since opioids augment abdominal muscle action during expiration, the unchanged pattern of movement can be attributed to both diaphragm and abdominal activity displacing the abdominal wall reciprocally, in the inspiratory and expiratory phases of the respiratory cycle, respectively.
authors.affiliation: Département d'Anésthesie et Réanimation, Hopital Henri Mondor, 51 Avenue du Marechal de Lattre de Tassigny, 94010 Creteil, France. g.b.drummond@ed.ac.uk
authors.forename: Gordon B
authors.initials: GB
authors.lastname: Drummond
authors.forename: Gilles
authors.initials: G
authors.lastname: Dhonneur
authors.forename: Krassen
authors.initials: K
authors.lastname: Kirov
authors.forename: Philippe
authors.initials: P
authors.lastname: Duvaldestin
mesh_terms: D000009:Abdominal Muscles / Q000187:drug effects*; D000328:Adult; D000402:Airway Obstruction / Q000503:physiopathology; D000403:Airway Resistance / Q000187:drug effects; D000701:Analgesics, Opioid / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D004347:Drug Interactions; D045853:Exhalation / Q000187:drug effects*; D005260:Female; D006801:Humans; D007530:Isoflurane / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial; D015656:Respiratory Mechanics / Q000187:drug effects*; D012132:Respiratory Muscles / Q000187:drug effects*; D035441:Thoracic Wall / Q000187:drug effects*; D013990:Tidal Volume / Q000187:drug effects
chemical_list: D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D009292:Narcotic Antagonists; D009270:Naloxone; D007530:Isoflurane