title: Protective role of aerodigestive reflexes against aspiration: study on subjects with impaired and preserved reflexes.
abstract: OBJECTIVE
  Direct evidence to support the airway protective function of aerodigestive reflexes triggered by pharyngeal stimulation was previously demonstrated by abolishing these reflexes by topical pharyngeal anesthesia in normal subjects. Studies have also shown that these reflexes deteriorate in cigarette smokers. Aim of this study was to determine the influence of defective pharyngeal aerodigestive reflexes on airway protection in cigarette smokers.
  
  
  METHODS
  Pharyngoglottal Closure reflex; PGCR, Pharyngo-UES Contractile reflex; PUCR, and Reflexive Pharyngeal Swallow; RPS were studied in 15 healthy non-smokers (24.2±3.3 SD y, 7 males) and 15 healthy chronic smokers (27.3±8.1, 7 males). To elicit these reflexes and to evaluate aspiration, colored water was perfused into the hypopharynx at the rate of 1 mL/min. Maximum volume of water that can safely dwell in the hypopharynx before spilling into the larynx (Hypopharyngeal Safe Volume; HPSV) and the threshold volume to elicit PGCR, PUCR, and RPS were determined in smokers and results compared with non-smokers.
  
  
  RESULTS
  At baseline, RPS was elicited in all non-smokers (100%) and in only 3 of 15 smokers (20%; P<.001). None of the non-smokers showed evidence of laryngeal spillage of water, whereas 12 of 15 smokers with absent RPS had laryngeal spillage. Pharyngeal anesthesia abolished RPS reflex in all non-smokers resulting in laryngeal spillage. The HPSV was 0.61±0.06 mL and 0.76±0.06 mL in non-smokers and smokers respectively (P=.1).
  
  
  CONCLUSIONS
  Deteriorated reflexive pharyngeal swallow in chronic cigarette smokers predispose them to risks of aspiration and similarly, abolishing this reflex in non-smokers also results in laryngeal spillage. These observations directly demonstrate the airway protective function of RPS.
authors.affiliation: Division of Gastroenterology and Hepatology, Medical College of Wisconsin, VA Medical Center, Milwaukee, Wisconsin, USA.
authors.forename: Kulwinder
authors.initials: K
authors.lastname: Dua
authors.forename: Sri Naveen
authors.initials: SN
authors.lastname: Surapaneni
authors.forename: Shiko
authors.initials: S
authors.lastname: Kuribayashi
authors.forename: Mohammed
authors.initials: M
authors.lastname: Hafeezullah
authors.forename: Reza
authors.initials: R
authors.lastname: Shaker
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003679:Deglutition; D004576:Electromyography; D005260:Female; D005683:Gagging; D005931:Glottis / Q000294:innervation*; D006801:Humans; D057045:Laryngopharyngeal Reflux / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D007828:Laryngoscopy; D008297:Male; D008365:Manometry; D010614:Pharynx / Q000294:innervation*; D011312:Pressure; D012021:Reflex, Abnormal; D012684:Sensory Thresholds; D012907:Smoking / Q000009:adverse effects*; D014741:Video Recording; D014922:Wisconsin; D055815:Young Adult