Active glottal closure during anoxic gasping in lambs.
The present study was aimed at assessing laryngeal dynamics and their consequences during anoxic gasping in ketamine-sedated lambs. We first verified that the glottis was closed between gasps during anoxic gasping in seven chronically instrumented lambs, aged 11-15 days. Recording of glottal constrictor muscle electrical activity, subglottal pressure and lung volume, together with endoscopic observation, confirmed the presence of active glottal closure with maintenance of a high lung volume between gasps. Secondly, we tested whether maintenance of a high lung volume between gasps improved autoresuscitation efficiency. Six sedated lambs aged 8-11 days underwent two anoxic runs, including one with an open tracheostomy to prevent maintenance of a high lung volume. Access back to air was allowed for gasping. No significant difference was found in time to eupnea resumption, hemodynamic parameters or arterial blood gases. We conclude that a high lung volume is actively maintained by glottal closure between anoxic gasps in sedated lambs. Further studies are however needed to define the importance of laryngeal dynamics during gasping.
Thuot
F
F
Pulmonary Research Unit, Department of Surgery, ENT Division, Université de Sherbrooke, Québec, J1H 5N4, Sherbrooke, Canada.
Lemaire
D
D
Dorion
D
D
Létourneau
P
P
Praud
J P
JP
D000818:Animals; D000831:Animals, Newborn; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000502:physiology; D002245:Carbon Dioxide / Q000097:blood; D004569:Electroencephalography / Q000187:drug effects; D004576:Electromyography; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005931:Glottis / Q000473:pathology / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D000860:Hypoxia / Q000503:physiopathology*; D007649:Ketamine / Q000494:pharmacology; D007773:Lactates / Q000097:blood; D008168:Lung / Q000503:physiopathology; D008176:Lung Volume Measurements; D010100:Oxygen / Q000097:blood; D015656:Respiratory Mechanics / Q000502:physiology*; D012132:Respiratory Muscles / Q000503:physiopathology; D012756:Sheep
D018691:Excitatory Amino Acid Antagonists; D007773:Lactates; D002245:Carbon Dioxide; D007649:Ketamine; D010100:Oxygen