Title	Lack of Evidence Suggests Caution in Using Nitrous Oxide Conscious Sedation in the Pregnant Dental Patient
Clinical Question	In a healthy patient during a normal pregnancy, is it safe to use nitrous oxide conscious sedation?
Clinical Bottom Line	The use of nitrous oxide in a pregnant patient is controversial. Suresh deemed limited nitrous oxide use safe for the pregnant patient after the first trimester, but due to the lack of human studies, nitrous oxide use should be used only when necessary and if postponing the procedure till after the pregnancy is not possible.
Best Evidence
PubMed ID Author / Year Patient Group Study type (level of evidence) 15184848 Suresh/2004 Narrative Review Key results In animal studies, nitrous oxide has been shown to inhibit methionine synthetase activity, but it is not known to have any affect in humans. Therefore, if nitrous oxide is required for an emergency dental procedure, it is best to wait till the patient is in the second or third trimester and should be administered with at least 50% oxygen for no longer than 30 minutes. Chronic exposure to nitrous oxide even at low levels has been shown to lead to spontaneous abortions. None UTHSCSA/2011 UTHSCSA Dental School policy Key results The UTHSCSA Dental School Nitrous Oxide Policy states that no pregnant patients, in any stage of the pregnancy, will be administered nitrous oxide for any dental procedure at the Dental School.
Evidence Search	Search "Pregnancy Complications" [Mesh] Search "DentalCare"
Comments on The Evidence	Suresh’s article gives a lot of great information but narrative reviews of animal experiments comprise low evidence. I do think that Suresh’s recommendations should be taken into consideration. Because the synthetase activity has not been shown to affect humans, there may be special situations where nitrous oxide can be used safely in a pregnant patient.
Applicability	My two references are contradictory, and currently there are not enough human studies to support the use of nitrous oxide conscious sedation in a pregnant patient. UTHSCSA dental school policy will remain unchanged until further research is presented to fully confirm nitrous oxide safety in the pregnant patient. Dentists not affiliated with UTHSCSA should use their best judgment when determining “necessary” emergency procedures and should always discuss the risks and lack of evidence with the pregnant patient before proceeding with nitrous oxide conscious sedation.
Specialty	(General Dentistry) (Oral Surgery) (Periodontics)
Keywords	Pregnancy complications, nitrous oxide, conscious sedation, adverse events
ID#	2063
Date of submission	06/02/2011
E-mail	lanenm@livemail.uthscsa.edu
Author	Nicole Lane
Co-author(s)
Co-author(s) e-mail
Faculty mentor	David Cox, DDS & Barbara MacNeill, DMD
Faculty mentor e-mail	macneill@uthscsa.edu; CoxD@uthscsa.edu
Basic Science Rationale (Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?) None available
Comments and Evidence-Based Updates on the CAT (FOR PRACTICING DENTISTS', FACULTY, RESIDENTS and/or STUDENTS COMMENTS ON PUBLISHED CATs) by Caroline Brown & Jeremy Morgan (San Antonio, TX) on 12/01/2017 A PubMed search on the safety of using nitrous oxide conscious sedation in the pregnant dental patient was performed on 11/28/2017. The article discussed in this CAT proved to be the highest level of evidence on this subject, suggesting there is a lack of evidence on this matter, and therefore using nitrous oxide conscious sedation in the pregnant dental patient should be performed with caution. Although there is insufficient evidence to conclusively answer this clinical question, there have been multiple studies examining the effectiveness of nitrous oxide sedation for the management of labor pain. A systematic review published in 2014 (PMID: 24356165) affirms the effectiveness and safety of nitrous oxide sedation, while including the minor adverse effects that have been seen during these procedures. Although this article confirms there is current research in the subject matter of nitrous oxide sedation and pregnant women, further research is needed to examine the effects of nitrous oxide conscious sedation, specifically in women and on the development of the fetus during different trimesters of the pregnancy, and if using this form of sedation during dental procedures could potentially lead to complications.