In This Issue
Nitrous Oxide in Labor: No Laughing Matter in Oregon
by Kara Johnson, DNP, RNC-OB, CNS
Use of inhaled nitrous oxide in labor for analgesia is common practice in several countries, but in the past few years has gained more attention in the United States. Several hospitals in Oregon have successfully implemented or are in the process of offering nitrous oxide for labor analgesia.
Nitrous oxide (aka N2O) is a gas that with inhalation provides analgesia and can also act as an anxiolytic. Most of us are familiar with its use for dental procedures and refer to it as “laughing gas.” Typically, dental procedure concentrations are about 70% nitrous oxide mixed with 30% oxygen. For laboring patients, the nitrous oxide is a lower, fixed concentration of 50% mixed with 50% oxygen. The lower concentration is associated with fewer side effects and prevents maternal desaturation (Stewart & Collins, 2012). Nitrous oxide enters and is eliminated from the body through the lungs. This allows less than 1% to be metabolized and greater than 99% eliminated through exhalation (Rooks, 2011). Patients control the dosing through self-administration only and dosing is determined by how they inhale and how long they use it.
In addition to providing analgesia, an advantage of nitrous oxide is it can be initiated or discontinued rapidly with quick clearance. The quick clearance allows a patient to change to another pain management option, such as an epidural, without delay. In fact, one study found that the epidural rate and cesarean rate did not change after implementing nitrous oxide for labor analgesia (Bobb, Farber, McGovern, & Camann, 2016). It can be used with other non-pharmacological pain management measures such as hydrotherapy. Nitrous oxide for labor analgesia can be administered in patients when epidural pain management is not an option such as hematologic disorders, spinal problems, localized infection at the injection site, or allergies to local anesthetics (Stewart & Collins, 2012). It also has been shown not to affect uterine contractions, labor progress, or the release of endogenous oxytocin (Rooks, 2011). Studies have demonstrated no effect on Apgar scores or neonatal behavior scores and another study on Chinese women demonstrated no differences in the incidence of meconium-stained fluid or cord blood gas results (Rooks, 2011).
Potential Side Effects and Contraindications
The most common side effects of nitrous oxide are nausea and vomiting. Some patients experience such severe nausea and vomiting that they choose to discontinue use. An increase in inner ear pressure can result if there is an obstruction or compromise in the Eustachian tube (Rooks, 2011). Nitrous oxide can cause drowsiness or lightheadedness so patients must be observed and/or assisted ambulating. Some contraindications include inability to self-administer holding mask, drug or alcohol impairment, impaired consciousness, recent history of trauma, pneumothorax, increased intracranial pressure or surgery, bowel obstruction, middle ear surgery, emphysema, pulmonary hypertension, and others (Stewart & Collins, 2012). Vitamin B-12 deficiency is considered a relative contraindication (Stewart & Collins, 2012).
Future of Nitrous Oxide Use in Labor
More research is needed on nitrous oxide use in labor. With several of the Oregon labor and delivery units implementing, or moving toward implementing, nitrous oxide administration during labor, there will be many research opportunities.
Oregon AWHONN has the pleasure of welcoming Michelle Collins, PhD, CNM, FACNM, Professor and Director of the Nurse Midwifery Program at Vanderbilt University, School of Nursing to the Oregon AWHONN conference September 25th-27th. Register today to hear more on nitrous oxide use in labor from a clinical expert in the area! §
Bobb, L.E., Farber, M.K., McGovern, C., & Camann, W. (2016). Does nitrous oxide labor analgesia influence the pattern of neuraxial analgesia usage? An impact study at an academic medical center. Journal of Clinical Anesthesia, 35, 54-57. doi: 10.1016/j.jclinane.2016.07.019
Rooks, J.P. (2011). Safety and risks of nitrous oxide labor analgesia: A review. Journal of Midwifery and Women’s Health, 56(6), 557-565. doi: 10.1111/j.1542-2011.2011.00122.x
Stewart, L.S. & Collins, M. (2012). Nitrous oxide as labor analgesia: Clinical implications for nurses. Nursing for Women’s Health, 16(5), 398-409. doi: 10.1111/j.1751-486X.2012.01763.x
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High Risk Obstetrics: Current Trends, Treatments and Issues Seminar
by PESI Healthcare
Sep 23, 2016
2016 Oregon AWHONN Fall Conference
by Oregon AWHONN
Sep 25 - 27, 2016
Introduction to Perinatal and Newborn Nursing, Part 2
Oct 3 - 5, 2016
Maternal & Newborn Review
by Professional Education Center and Oregon AWHONN
Oct 5 - 7, 2016