Why can't i have sedation for esophageal manometry?

Alter results : Any 'sedation' may influence the accuracy of the results...Manometry essentially measures a few items: pressure and proper direction of contractions in the body of the esophagus and pressure and appropriately timed relaxation of the sphincter of the esophagus.

Sedation: Usually that study is done without sedation, but some patients cannot tolerate it so light sedation can be used and still get good study results.