title: Effect of chronic and acute cigarette smoking on the pharyngo-upper oesophageal sphincter contractile reflex and reflexive pharyngeal swallow.
abstract: BACKGROUND
  Cigarette smoking is known to affect adversely the defence mechanisms against gastro-oesophageal reflux. The effect of smoking on the supraoesophageal reflexes that prevent aspiration of gastric contents has not been previously studied.
  
  
  OBJECTIVE
  To elucidate the effect of cigarette smoking on two of the supraoesophageal reflexes: the pharyngo-upper oesophageal sphincter (UOS) contractile reflex; and the reflexive pharyngeal swallow.
  
  
  METHODS
  Ten chronic smokers and 10 non-smokers were studied, before and 10 minutes after real or simulated smoking, respectively. UOS pressure and threshold volume for the reflexes were determined using a UOS sleeve assembly. Two modes of fluid delivery into the pharynx were tested: rapid injection and slow injection.
  
  
  RESULTS
  For both rapid and slow injections, the threshold volume for triggering the pharyngo-UOS contractile reflex was significantly higher in smokers than in non-smokers (rapid: smokers 0.42 (SE 0.07) ml, non-smokers 0.16 (0. 04) ml; slow: smokers 0.86 (0.06) ml, non-smokers 0.38 (0.1) ml; p<0. 05). During rapid injection, the threshold volume for reflexive pharyngeal swallow was higher in smokers (smokers 0.94 (0.09) ml, non-smokers 0.46 (0.05) ml; p<0.05). Acute smoking further increased the threshold volume for the pharyngo-UOS contractile reflex and reflexive pharyngeal swallow during rapid injection.
  
  
  CONCLUSIONS
  Smoking adversely affects stimulation of the pharyngo-UOS contractile reflex and pharyngeal reflexive swallow. These findings may have implications in the development of reflux related respiratory complications among smokers.
authors.affiliation: MCW Dysphagia Institute, Department of Medicine, Medical College of Wisconsin and Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA.
authors.forename: K
authors.initials: K
authors.lastname: Dua
authors.forename: E
authors.initials: E
authors.lastname: Bardan
authors.forename: J
authors.initials: J
authors.lastname: Ren
authors.forename: Z
authors.initials: Z
authors.lastname: Sui
authors.forename: R
authors.initials: R
authors.lastname: Shaker
mesh_terms: D000328:Adult; D003679:Deglutition / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010614:Pharynx / Q000502:physiology*; D011312:Pressure; D011930:Reaction Time; D012018:Reflex / Q000502:physiology*; D012907:Smoking / Q000503:physiopathology*