N2O/O2 versus O2 use during Conscious Sedation

Resident: Swan

Article Title: The Physiological effects of supplemental oxygen versus nitrous oxide/oxygen during conscious sedation of pediatric dental patients

Author: Leelataweewud, et al

Journal: Pediatric Dentistry, Volume (Number): 22:2, 2000
Major Topic: Conscious sedation using an oral narcotic regimen with adjunctive oxygen or nitrous oxide/oxygen

Type of Article: Scientific article

Main Purpose: compare the effects of N20/O2 versus O2 as adjuncts to an oral narcotic regimen during pediatric conscious sedation

Background: The use of N20/O2 as an adjunct during CS is a widely practiced and well-researched technique, although some studies do indicate that N20 use can compromise the airway of a sedated child. Supplemental O2 administration during CS has also been the subject of previous research—the thinking behind it is that supplemental O2 elevates arterial oxygen tension to much higher levels than normal and also increases residual functional capacity, providing an O2 reserve in the case where a child’s breathing slows or stops during sedation. (preventing desaturation, or a drop in SpO2 of 5% from baseline in an immobile, quiet patient.) Studies have supported this use of supplemental O2. Other studies comparing the two techniques have shown no difference in physiologic parameters (PR, SpO2, RR), with better sedation using nitrous.

Overview of method of research: 19 children were included in this randomized double-blind crossover stud. Each child served as their own control by either receiving O2 or N2O/O2 supplementation during two operative visits. The investigators were blinded as to this initial assignment. Baseline vitals were taken for each patient, and all patients were given an oral regimen of 50 mg/kg chloral hydrate, 25 mg hydroxyzine, and 1.5 mg/kg meperidine. 45 minutes after administration, the kids were transferred to the operatory, papoosed, and attached to monitors. Treatment was planned so that each of the two visits would have comparable difficulty and length, but if patients were well-sedated and cooperative, the operator did as much work as possible. PR, RR, SpO2, and end-tidal CO2 were measured every 5 minutes. The PI recorded levels of sedation during the appointments using an AAPD approved subjective scale. The overall sedation outcome was assessed at the end using another subjective scale. Data were statistically analyzed.

Findings: The differences in PR and SpO2 between different visits were not statistically significant, while effect on RR was marginally significant (N2O actually increased RR in this study). There were more desaturation events using N2O/O2, but the difference was not significant (mean of 5.9 events for N2O appts, 3.6 in the O2 group). Level of sedation was higher with the N2O group, and this finding was statistically significant. The final evaluations of the sedations were as follows: with O2 use, 42% excellent, 37 % unsatisfactory, and 21% unsatisfactory. With N2O use, 69%, 26%, and 5% respectively.

Key Points/Summary:
1. No difference in physiologic parameters was noted during treatment.
2. N2O did not increase risk of desaturation but did increase frequency of desaturation events and airway repositioning after desaturation episodes.
3. N2O deepened sedation levels with this narcotic regimen
4. N2O improved sedation outcomes
5. When N2O is used, children should be monitored very closely

Assessment of Article:I had not heard of O2 supplementation during CS, but it appears N2O provides much better sedation as one may assume. The subjectivity of the assessment scales used is a potential limitation, but is the most feasible method of evaluation. I thought it was a good study overall.