title: Vagal response varies with Valsalva maneuver technique: a repeated-measures clinical trial in healthy subjects.
abstract: OBJECTIVE
  Variable success rates of the Valsalva maneuver in treatment of paroxysmal supraventricular tachycardia may be due to variations in performance technique. This study aimed to compare the magnitude of the vagal reflexes initiated by 5 variations of the Valsalva maneuver technique (supine, supine with epigastric pressure, supine with leg raise, semirecumbent position, and sitting position).
  
  
  METHODS
  This was a single-blinded, repeated-measures, clinical trial of 65 subjects in sinus rhythm. Subjects performed each Valsalva maneuver technique 5 times in random order. The means of the longest ECG R-R intervals during the relaxation phase (postmaneuver R-R interval) and the postmaneuver pulse rates for each technique were compared. The mean differences between the pre- and postmaneuver R-R intervals for each technique were also compared.
  
  
  RESULTS
  The supine with epigastric pressure and supine techniques resulted in longer mean postmaneuver R-R intervals (1.082 seconds [95% confidence interval (CI) 1.045 to 1.119 seconds] and 1.075 seconds [95% CI 1.035 to 1.114 seconds], respectively) than the leg raise, semirecumbent, and sitting position techniques (1.053 seconds [95% CI 1.019 to 1.086 seconds], 1.044 seconds [95% CI 1.006 to 1.081 seconds], and 1.024 seconds [95% CI 0.990 to 1.059 seconds], respectively), which equates to slower mean postmaneuver pulse rates for the supine with epigastric pressure and supine techniques (55.5 and 55.8 beats/min, respectively) than the leg raise, semirecumbent, and sitting position techniques (57.0, 57.5, and 58.6 beats/min, respectively). The supine with epigastric pressure and supine techniques also resulted in the largest premaneuver versus postmaneuver differences.
  
  
  CONCLUSIONS
  For healthy subjects in sinus rhythm, the supine with epigastric pressure and supine techniques generated stronger vagal responses, as measured by R-R intervals and pulse rates, than the other techniques examined. However, the vagal responses of these 2 techniques were similar, and the addition of epigastric pressure may confer little advantage.
authors.affiliation: Emergency Department, Royal Melbourne Hospital, Parkville, Australia.
authors.forename: Lu Fee
authors.initials: LF
authors.lastname: Wong
authors.forename: David M
authors.initials: DM
authors.lastname: Taylor
authors.forename: Michael
authors.initials: M
authors.lastname: Bailey
mesh_terms: D000328:Adult; D017704:Baroreflex / Q000502:physiology; D004562:Electrocardiography; D004825:Epiglottis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology; D016037:Single-Blind Method; D016683:Supine Position / Q000502:physiology*; D013614:Tachycardia, Paroxysmal / Q000628:therapy; D013617:Tachycardia, Supraventricular / Q000628:therapy; D014630:Vagus Nerve / Q000502:physiology*; D014636:Valsalva Maneuver / Q000502:physiology