Nitrous Oxide for Pain Management During In-office Transcervical Sterilization

Hysteroscopic permanent sterilization with Essure® is increasingly performed in the outpatient setting. No optimal outpatient analgesia regimen has been identified for the Essure® procedure. The investigators propose a study of inhaled nitrous oxide administered with oxygen, hereafter referred to as nitrous oxide (NO), as an intervention to lower pain experienced during the in-office procedure. The investigators hypothesize that, compared to standard oral medications, inhaled NO will decrease patient anxiety associated with the in-office procedure, as well as increase patient satisfaction and provider perceived ease of device insertion.

Women presenting to the clinic for family planning will receive our standard counseling on all forms of contraception, including short and long acting reversible contraception, and methods for permanent sterilization. Once the patient decides to have a sterilization procedure with the transcervical approach (Essure® procedure), she will undergo the standard pre-procedure evaluation, which includes a complete history, appropriate physical examination including pelvic examination, and urine pregnancy test.

Eligible women interested in sterilization will be advised of the study as an investigation evaluating nitrous oxide as an alternative to our current oral sedation pain management for in-office procedures. If they choose hysteroscopic sterilization, they will undergo informed consent for the Essure® procedure. Providers will assess patient eligibility criteria for possible enrollment into the study. If patients are eligible and choose to participate in the research study, consent for participation will be obtained. At this time patients will be randomized to treatment group based on a predetermined randomization scheme. For this research study comparing the use of NO versus oral pain medications, the NO group will receive two placebo pills and the standard group will receive one 5/325 mg oral tablet of Vicodin and one 1 mg oral tablet of lorazepam 30 minutes prior to the procedure. The standard care group will receive oxygen (instead of NO) during the procedure. All participants will receive 30 mg of intramuscular ketorolac 30 minutes prior to the procedure.

NO or oxygen will be administered via a scented nasal mask to blind patients to the intervention. NO can be titrated up to a concentration of 70% nitrous oxide and 30% oxygen based on desired analgesic effects per a predetermined sedation scale as part of the University of New Mexico Center for Reproductive Health (UNM CRH) nitrous administration protocol. All patients will be monitored with a pulse-oximeter. The patient will be fitted to their mask once the procedure is ready to begin. A single nurse will administer nitrous oxide and oxygen for all procedures. Every study patient will receive a minimum of 3 minutes of oxygen at the end of the procedure to minimize the side effects of NO. Additional oxygen will be administered as needed if a patient is experiencing residual effects of NO.

Prior to the procedure and study medications, patients will complete patient information and demographics questionnaire and will receive instruction on the 0-100mm visual analogue scale (VAS) and Spielberger State-Trait Anxiety Inventory (STAI). A baseline pain score will be recorded using the 0-100mm VAS with anchors 0 equals no pain and 100 equals worst pain imaginable, as well as baseline anxiety level using the STAI. At placement of the paracervical block and deployment of the second device coil, pain will be assessed again with the same 0-100mm VAS. At 3 to 5 minutes following completion of the procedure, maximal pain experienced during transcervical sterilization will be assessed by the patient. Prior to discharge from the clinic, the patient will rate her pain level using the same 0-100mm VAS, rate her level of anxiety with the procedure using the same STAI, and rate her overall satisfaction with the procedure measured using a 5-point Likert scale.