Nitrous oxide for pain management during in-office hysteroscopic sterilization: a randomized controlled trial.
OBJECTIVE
To evaluate whether inhaled nitrous oxide with oxygen (N2O/O2) is associated with less pain compared to oral sedation for pain management during in-office hysteroscopic sterilization.


METHODS
This double blinded randomized controlled trial enrolled women undergoing in-office hysteroscopic sterilization. All participants received pre-procedure intramuscular ketorolac and a standardized paracervical block. The intervention group also received N2O/O2via a nasal mask titrated to a maximum 70%:30% mixture by a nurse during the procedure and placebo pills pre-procedure and the active control group received inhaled O2during the procedure and 5/325 mg hydrocodone/acetaminophen and 1 mg lorazepam pre-procedure. The primary outcome was maximum procedure pain on a 100 mm Visual Analog Scale (VAS with anchors at 0=no pain and 100=worst imaginable pain) assessed 3-5 min post procedure. Thirty women per treatment arm were required to detect a clinically significant pain difference of 20 mm.


RESULTS
Seventy-two women, 36 per study arm, were randomized. Mean age of participants was 34.1±5.7 years and mean BMI was 30.1±6.6kg/m2. Mean maximum procedure pain scores were 22.8±27.6 mm and 54.5±32.7 mm for intervention and control groups, respectively (p<.001). Most study participants (97%) stated N2O/O2should be offered for gynecologic office procedures and 86% would pay for it if not a covered benefit.


CONCLUSIONS
N2O/O2decreased pain with in-office hysteroscopic sterilization compared to oral sedation and is an effective pain management option for this procedure.


CONCLUSIONS
Given its safety and favorable side effect profile, N2O/O2can be used for pain management for in-office hysteroscopic sterilization and adds a safe, easily administered option to currently available strategies.
University of New Mexico, Department of Obstetrics and Gynecology, 1 University of New Mexico, MSC10 5580, Albuquerque, NM 87131, USA. Electronic address: schneidsem@gmail.com.
Emily N
EN
Schneider
University of New Mexico, Department of Obstetrics and Gynecology, 1 University of New Mexico, MSC10 5580, Albuquerque, NM 87131, USA. Electronic address: reriley@salud.unm.edu.
Regan
R
Riley
University of New Mexico, Department of Obstetrics and Gynecology, 1 University of New Mexico, MSC10 5580, Albuquerque, NM 87131, USA. Electronic address: eespey@salud.unm.edu.
Eve
E
Espey
University of New Mexico, Department of Pediatrics, 1 University of New Mexico, MSC 10 5590, Albuquerque, NM, USA. Electronic address: SMishra@salud.unm.edu.
Shiraz I
SI
Mishra
University of New Mexico, Department of Obstetrics and Gynecology, 1 University of New Mexico, MSC10 5580, Albuquerque, NM 87131, USA. Electronic address: rhsingh@salud.unm.edu.
Rameet H
RH
Singh
D000328:Adult; D018685:Anesthetics, Inhalation / Q000627:therapeutic use*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D015907:Hysteroscopy; D009516:New Mexico; D009609:Nitrous Oxide / Q000627:therapeutic use*; D010044:Outpatient Clinics, Hospital; D059408:Pain Management / Q000379:methods; D010147:Pain Measurement; D011247:Pregnancy; D013245:Sterilization, Reproductive
D018685:Anesthetics, Inhalation; D009609:Nitrous Oxide
Hysteroscopic sterilization; Nitrous oxide; Pain; Sedation