title: Perioperative topical nitrate and sphincter function in patients undergoing transanal stapled anastomosis: a randomized, placebo-controlled, double-blinded trial.
abstract: OBJECTIVE
  The use of transanal stapling devices may impair continence because of digital dilatation and/or instrumentation. This study assessed the effect of pharmacological dilatation of the sphincter prior to stapler insertion.
  
  
  METHODS
  A randomized, placebo-controlled, double-blinded study of 60 patients undergoing transanal stapled anastomosis was undertaken. Consenting patients were randomly assigned to receive a single intraoperative dose of topical 0.2 percent nitroglycerin (glyceryl trinitrate) ointment or nitroglycerin-free placebo. All patients were assessed preoperatively and postoperatively by clinical methods (Wexner incontinence scores and examination), anorectal manometry by a station pull-through technique, and endoanal ultrasonography.
  
  
  RESULTS
  Intraoperative mean (+/-SEM) resting pressures (mmHg) were significantly reduced by nitroglycerin compared with prenitroglycerin levels (9.9 +/- 0.9 vs. 50.5 +/- 2.7; P = 0.002) or controls (56.0 +/- 3.2; P = 0.001). Twenty-one of the 28 controls (75 percent) but only 4 of the 32 patients in the nitroglycerin group (12.5 percent) required digital dilatation to insert the stapling instrument ( P = 0.003). Squeeze pressures were unaltered by the intervention but mean resting pressures were higher in the nitroglycerin group postoperatively (52.9 +/- 3.2 - 31.6 +/- 1.3 = 21.3 mmHg; 95 percent confidence interval, 14-27). Incontinence scores were lower in the nitroglycerin group at the 3-month (1.1 +/- 0.2 vs. 4.6 +/- 0.3; P = 0.003) and 12-month (0.9 +/- 0.1 vs. 4.4 +/- 0.3; P = 0.002) clinic visits.
  
  
  CONCLUSIONS
  Preoperative nitroglycerin dilatation protects sphincter function in patients undergoing transanal stapled anastomoses.
authors.affiliation: Academic Department of Surgery, National University of Ireland, Cork University Hospital, Wilton, Ireland. winterd@indigo.ie
authors.forename: D C
authors.initials: DC
authors.lastname: Winter
authors.forename: A
authors.initials: A
authors.lastname: Murphy
authors.forename: M R
authors.initials: MR
authors.lastname: Kell
authors.forename: C J
authors.initials: CJ
authors.lastname: Shields
authors.forename: H P
authors.initials: HP
authors.lastname: Redmond
authors.forename: W O
authors.initials: WO
authors.lastname: Kirwan
mesh_terms: D000287:Administration, Topical; D000368:Aged; D001003:Anal Canal / Q000187:drug effects / Q000503:physiopathology* / Q000601:surgery*; D000714:Anastomosis, Surgical; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008365:Manometry; D008875:Middle Aged; D005996:Nitroglycerin / Q000008:administration & dosage*; D009824:Ointments; D017792:Surgical Stapling; D014665:Vasodilator Agents / Q000008:administration & dosage*
chemical_list: D009824:Ointments; D014665:Vasodilator Agents; D005996:Nitroglycerin