Each year, Childbirth Today Blog brings a series called “The Evidence
Says”. This series covers major topics
discussed in maternity care. The 2014
Series begins with the topic: Nitrous Oxide.
Nitrous Oxide, or N2O, has been a common pain
reliever for labor and childbirth in Europe, Canada and Australia for several centuries. First produced by an English chemist in 1772,
it was the first anesthetic to be commonly used but was replaced by either and
chloroform due to the potency. Nitrous
oxide depresses normal brain function, although exactly how has not been
discovered. It is thought to increase
the release of endorphin, dopamine and other natural pain relievers in the
brain. Nitrous also has an anti-anxiety
effect, which may help women with tocophobia.
When nitrous oxide is inhaled, it quickly mixes with the air
in the lungs. It then passes into the
bloodstream and into general circulation.
The gas then changes to a solution and reaches the brain in
approximately 20 seconds. The amount of
gas that reaches the brain depends on the concentration inhaled and how long it
is inhaled. Like other substances,
nitrous oxide crosses the
placental barrier and enters the baby’s blood
stream. However, unlike other
medications, nitrous oxide does not have to be broken down by the liver and is
thus metabolized and excreted rapidly.
Because of this rapid metabolization, the medication does not become
concentrated in either the maternal or fetal body. Nitrous oxide is considered
safe for mothers, baby’s and care providers when the nitrous is delivered as a
50% blend with oxygen.
The odorless nitrous oxide is delivered via a machine (with
mask) that mixes the gas with oxygen in certain percentages. The gas is only delivered when the machine detects
that someone is inhaling into the mask.
The mask reduces wastage and tries to prevent others in the room from
experiencing the effects of the gas.
There are various types of machines on the market, however availability
is limited in the U.S. The University
of California San Francisco birth center has had their own machines for years,
even after some the nitrous oxide machine manufacturers in the U.S. ceased
production of the machines, after the surge in popularity of the epidural and
other medications used for labor/birth.
It is reported that other U.S. facilities use nitrous oxide including
University of Washington Hospital in Seattle, St. Joseph Regional Medical
Center in Idaho, Okanogan Douglas Hospital in Washington, and Vanderbilt in
Tennessee. This patient information page
appears on the Dartmouth-Hitchcock Children’s Hospital at Dartmouth in New
Hampshire – Click Here. The American
College of Nurse-Midwives have a detailed position paper on the use of nitrous
oxide.
The advantages of self-administering nitrous oxide include
increase perception of control, can be used anytime during labor, does not
appear to have adverse effects on the baby’s condition at the moment of birth,
can be quickly administered and the effects are nearly immediate, effects
reverse when inhalation stops, does not require the presence of an
anesthesiologist. While there are few
reported complications using nitrous oxide as an anesthetic during labor and
birth, nitrous does appear to have more side effects such as nausea, vomiting,
dizziness and drowsiness. Nitrous oxide
administration does limit position changes and movement due to the mask being
connected to the administration machine and may cause additional complications
if used in conjunction with other pain relievers.
More research about the use of Nitrous Oxide for use during
labor and birth. However, at first
glance, it does appear to be preferable to narcotics and epidural anesthesia.
References and
Resources:
American College of Nurse-Midwives (2011) Position Statement: Nitrous Oxide for
Labor Analgesia. Last access 1/21/14.
Agency for Healthcare Research and Quality. (2012).
Executive Summary: Nitrous Oxide for Management of Labor Pain. Last access 1/21/14.
http://www.effectivehealthcare.ahrq.gov/ehc/products/260/1230/CER67_NitrousOxide_ExecutiveSummary_20120817.pdf
http://www.effectivehealthcare.ahrq.gov/ehc/products/260/1230/CER67_NitrousOxide_ExecutiveSummary_20120817.pdf
Baysinger, C. and the
American Society of Anesthesiologists Research Statement (no date)
http://www.asahq.org/For-Members/Clinical-Information/Nitrous-Oxide.aspx#adverse
http://www.asahq.org/For-Members/Clinical-Information/Nitrous-Oxide.aspx#adverse
College of Midwives of Ontario (2012) Position Statement:
The Use of Nitrous Oxide at Home Births.
Last access 1/21/14.
http://www.cmo.on.ca/documents/GCMO_C020812_TheUseofNitrousOxideatHomeBirths_Council_FEB82012.pdf
http://www.cmo.on.ca/documents/GCMO_C020812_TheUseofNitrousOxideatHomeBirths_Council_FEB82012.pdf
Jones, L. et al. (2012) Pain management for women in labor:
an overview of systematic reviews.
Cochrane Database of Systematic Reviews. Mar 14;3.
Klomp, T. et al. (2012) Inhaled analgesia for pain
management in labor. Cochrane Database
Systematic Review, September 12;9.
Rooks, J.P. (2011) Safety and risks of nitrous oxide labor
analgesia: a review. Journal of Midwifery and Womens Health. Nov/Dec. 56(6):557-65.
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