title: Effect of viral upper respiratory tract infection on the urge-to-cough sensation.
abstract: BACKGROUND
  Recently, interest has emerged in the sensation of irritation that precedes the motor act of coughing; this phenomenon has been termed the urge-to-cough (UTC). Although one previous study has demonstrated a transient enhancement of cough reflex sensitivity during acute upper respiratory tract infection (URI), the effect of URI on UTC has not previously been investigated.
  
  
  METHODS
  Employing standard cough challenge methodology, we measured cough reflex sensitivity in 24 otherwise healthy adult nonsmokers during URI and again after recovery (4-8 weeks later) by determining C(2) and C(5), the concentrations of capsaicin inducing 2 or more and 5 or more coughs, respectively. In addition, we determined the capsaicin concentration at which the UTC sensation first occurred, without an associated motor cough, and termed it C(u). Furthermore, we determined the difference between concentrations of capsaicin inducing the first motor event of cough (C(1)) and C(u), and have termed it C(Δ).
  
  
  RESULTS
  During URI, cough reflex sensitivity as measured by C(1) (p = 0.033) and C(5) (p = 0.001), as well as the urge-to-cough threshold, C(u) (p = 0.046), were significantly enhanced compared to the post-recovery state. The degree of change in cough reflex sensitivity (C(5)) was significantly greater than that of the urge-to-cough threshold, C(u) (p = 0.044).
  
  
  CONCLUSIONS
  Our results demonstrate that the UTC sensation is transiently enhanced during URI. We also confirm the results of the lone previous study that demonstrated transient enhancement of cough reflex sensitivity during URI. The UTC threshold may represent an additional relevant end point to measure in future studies evaluating potential antitussive agents.
authors.affiliation: Albert Einstein College of Medicine, Montefiore Medical Center, 1825 Eastchester Road, Bronx, NY, USA. pdicpinigaitis@pol.net
authors.forename: Peter V
authors.initials: PV
authors.lastname: Dicpinigaitis
authors.forename: Rajani
authors.initials: R
authors.lastname: Bhat
authors.forename: William A
authors.initials: WA
authors.lastname: Rhoton
authors.forename: Amit S
authors.initials: AS
authors.lastname: Tibb
authors.forename: Abdissa
authors.initials: A
authors.lastname: Negassa
mesh_terms: D000328:Adult; D000996:Antitussive Agents / Q000627:therapeutic use; D002211:Capsaicin; D003139:Common Cold / Q000188:drug therapy / Q000503:physiopathology*; D003371:Cough / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D012018:Reflex / Q000187:drug effects; D012677:Sensation / Q000187:drug effects; D018689:Sensory System Agents
chemical_list: D000996:Antitussive Agents; D018689:Sensory System Agents; D002211:Capsaicin