///2010 Abstract Details
2010 Abstract Details2019-08-03T15:49:10-06:00

Nitrous Oxide for Relief of Pain in Laboring Women: Study in Progress

Abstract Number: 102
Abstract Type: Original Research

Jessica D. Bauerle B.S.1 ; Andrea Fuller M.D.2; Joy Hawkins M.D.3; Matthew Fiegel M.D.4; Brenda Bucklin M.D.5


Nitrous oxide (N2O) has been used for over a century to help relieve labor pain in the parturient. Currently, however N2O is rarely used in the U.S. and is often unavailable during labor. This study is being conducted at an elevation of 5280 ft. above sea level in Denver, CO. Our aim is to measure the safety and efficacy of N2O in parturients at altitude, as well as overall patient satisfaction. We hypothesize that 1) N2O (50-70%) administered by nasal mask will provide analgesia for labor at altitude, 2) there will be no adverse effects on maternal or neonatal outcome, 3) maternal request for additional analgesia during the study period will be delayed or eliminated with N2O, 4) maternal satisfaction will be acceptable with N2O delivered by nasal mask, and 5) end-expired alveolar N2O concentrations will vary considerably from inspired N2O concentrations over the time of application.


Following IRB approval, healthy parturients with uncomplicated pregnancies at term are approached about interest in the study in the midwifery clinic at the University of CO Hospital. Patients are re-consented after admission to labor and delivery. At first request for analgesia, N2O is administered. Patients desiring another pain relief method must discontinue N2O administration. Duration of administration is up to 3 hours by nasal mask, with a nasal probe in place to measure end tidal gas content. Waste gases are scavenged through suction connected to the mask. Prior to and during administration, vital signs, VAS pain scale, and side effects are monitored every 10 minutes. Fetal heart rate tracings are continuously monitored. An anesthesia gas monitor is used to continuously analyze end-inspired and expired alveolar N2O and O2 concentrations as well as PETCO2 from the nasopharyngeal probe. Correlation of PETCO2 validates sampling methodology (1). Data are recorded using S5 Datacollect software.


Total enrollment is set at 20 patients. Six have participated thus far. N2O has been safe, with only minor side effects to mother, including dry mouth and dizziness that resolved following mask removal. No neonatal adverse effects have been observed. VAS measurements have not changed from baseline. Three patients requested an alternative means of pain relief other than the N2O. During post op visits 24h after delivery, patients have been generally satisfied and stated their intention to utilize N2O for subsequent deliveries.


Thus far, we have shown that N2O is a safe, non-invasive means of labor analgesia, with relatively few minor side effects for both mother and baby. It has also been shown to be efficacious, with high maternal satisfaction. Completion of the study will provide further evidence of the safety and efficacy parameters, as well as maternal satisfaction.

1. Pediatr Dent 2004; 26: 410-6

SOAP 2010