Nitrous Oxide for Pain Management During In-Office Gynecology Procedures (NO2)

Many hysteroscopic procedures require only minimal sedation in order to accomplish adequate pain control and sufficient anesthesia for completion of the procedure. In order to avoid the higher costs and time associated with hospital-based procedures, there is a growing trend to complete these procedures in an office-based setting with IV sedation. With IV sedation, the patients are required to have a ride to and from the appointment, maintain an NPO status for at least 8 hours prior to the appointment, receive proper IV placement prior to the procedure, and remain in the recovery area until anesthesia has worn off, which can take 30 minutes to 1 hour. Several studies in the family planning literature have shown promising results using nitrous oxide for anesthesia during simple in-office procedures such as ****. One pilot study from Madrid demonstrated superior pain control with nitrous oxide when compared to ****.

We believe that nitrous oxide can be a safe, effective, and favorable method for anesthesia for quick and simple office-based gynecologic procedures. Not only will nitrous oxide provide an equal level of pain control, but it also provides several benefits to the patient and the physician. Using nitrous oxide will not require the patient to withstand an uncomfortable IV placement, to maintain NPO status prior to the procedure, or to coordinate a ride before and after the procedure. For the physician, using nitrous oxide for procedures will provide quicker recovery times, allowing physicians to potentially provide services to more patients within a single clinic day.

Nitrous oxide (N2O) was first isolated in 1772 by the English chemist Joseph Priestly and was later discovered to have analgesic properties by Humphry Davy almost twenty years later (Boyle, Goerig, Huang, Priestly). Its role as an analgesic did not take hold until 1863 when Gardner Quincy Colton established the use of nitrous oxide for dental procedures. After its introduction to dentistry, N2O soon became a popular form of pain management in both obstetrics and surgery (Goerig, Huang, Smith).

Nitrous oxide, when inhaled, has both analgesic and anesthetic properties. The exact anesthetic mechanism of action is not completely understood but is thought to be due to non-competitive inhibition of the excitatory NMDA subtype glutamate receptors (Jevtovic). Nitrous oxide provides analgesia by stimulating opioid receptors in the periaqueductal gray matter and noradrenergic receptors in the brainstem, causing a release of endogenous opioids. This release of endogenous opioids dis-inhibits noradrenergic neurons in the brainstem by inhibiting the inhibiting GABA receptors. Consequently, norepinephrine is released into the spinal cord, thereby inhibiting pain signaling (Fujinaga, Sanders).

Although nitrous oxide has been documented as a safe and effective method for pain relief in many areas of medicine, specifically obstetrics, little research exists about its use for pain management for in-office gynecologic procedures. One study by Singh et al evaluated the role of Nitrous Oxide vs no intervention for IUD insertion in nulliparous women and found that nitrous oxide did not reduce pain (Singh). A pilot study by Rubido et al examined nitrous oxide versus no intervention versus paracervical block in women undergoing hysteroscopic polypectomy and found that nitrous oxide outperformed both the control group and paracervical group (Rubido). A third randomized controlled trial studied the superiority of nitrous oxide versus oral analgesia and discovered that nitrous oxide significantly reduced pain scores compared to the control group (Schneider). The purpose of this study is to examine the non-inferiority of nitrous oxide to intravenous sedation for pain management during in-office gynecologic procedures.