title: Mechanisms of airway protection after pharyngeal fluid infusion in healthy sleeping piglets.
abstract: The airway protective mechanisms evoked after infusion of fluids into the pharynx were examined in the intact and healthy newborn piglet during sleep. Thirteen healthy normothermic piglets (3-6 days of age) were examined on 4 consecutive days during sleep. The fluids infused (0.05-1.5 ml) were 0.9% saline, distilled water, and HCl (pH 3 and pH 2). Respiratory rate, heart rate, oxygen saturation (SaO2), swallowing, and arousal were compared pre- and postinfusion during active (AS) and quiet sleep (QS) for each test fluid. The most common response in AS and QS was swallowing (90%) and then arousal (24%); however, no apnea occurred, and respiratory rate and SaO2 were always maintained. A significant difference occurred between HCl infusions of pH 2 and pH 3; at pH 2, the frequency of swallows and latency to the first swallow were reduced (P < 0.05) and the frequency of arousal was reduced in AS compared with that in QS (P < 0.01). Airway protection after pharyngeal fluid stimulation is achieved primarily by swallowing and arousal, without any effect on respiratory rate and SaO2. Attenuation of protective mechanisms occurred, however, when the infusate was at pH 2.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Sydney, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Page
authors.forename: H E
authors.initials: HE
authors.lastname: Jeffery
authors.forename: V
authors.initials: V
authors.lastname: Marks
authors.forename: E J
authors.initials: EJ
authors.lastname: Post
authors.forename: A K
authors.initials: AK
authors.lastname: Wood
mesh_terms: D000818:Animals; D001143:Arousal / Q000502:physiology; D001522:Behavior, Animal / Q000502:physiology; D001826:Body Fluids / Q000502:physiology*; D003371:Cough / Q000139:chemically induced / Q000503:physiopathology; D003679:Deglutition / Q000502:physiology; D004569:Electroencephalography / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006851:Hydrochloric Acid / Q000008:administration & dosage / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008297:Male; D010614:Pharynx / Q000502:physiology*; D012018:Reflex / Q000502:physiology; D015656:Respiratory Mechanics / Q000502:physiology; D012143:Respiratory Physiological Phenomena; D012890:Sleep / Q000502:physiology*; D012912:Sneezing / Q000502:physiology; D012965:Sodium Chloride / Q000008:administration & dosage / Q000494:pharmacology; D013552:Swine; D014867:Water / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D014867:Water; D012965:Sodium Chloride; D006851:Hydrochloric Acid