I believe it would foul your test results. We are told to obtain blood and urine for tox screen. The sedative you give may be the one that may have been used, thus cancelling out a consent issue. The SAE is trained to establish rapport with the patient, move at a pace that the patient is comfortable with, explain the exam procedure, also giving the patient the power to stop at any time and provide the patient with an advocate to be present during the exam.
The SAE also needs to document the demeanor of the patient before, during and after the exam which includes any statements the person may say so sedation would sort of diminish the outcome in my opinion. I guess you could suggest a little something afterword provided it is ordered by a Physician, however should be done seperately so as not to be a part of the exam record.