Depends on what system you are using. Start with 100% O2 for a few minutes slowly titrate N2O until pt achieves the sedative effects of tingling fingers…etc… Use the lowest amount that works for the patient. Some systems need to be calibrated with the manufacture over the years. Also, if it takes over 55-65% N2O then check the masks. The masks do age and need to be replaced over years of use. Also run a test monthly or every other month while treating a pt to make sure only the pt is getting the nitrous and not the whole office.
The more you use nitrous on patients the more comfortable you’ll become. A few tips are start the O2 before you place the nose piece on the pt. Also after they breathe in O2 for 5 mins at the end of the appt, leave the O2 going as you take the nose piece off. This makes it more comfortable for the pt. Be sure to take BP before and after the appt and chart your findings. Remind the pt to breathe through their nose during the appt and limit the amount of talking to reduce nitrous from escaping into the room.
Write yourself a “cheat sheet” so when you do administer you can quickly reference. I did this until I was comfortable. When I first started sometimes I would go months between administration and this really helped me. Ask other hygienists or the Dr. in your office for any tips on your specific unit to add to your cheat sheet.