The effects of nitrous oxide on behavior and physiological parameters during conscious sedation with a moderate dose of chloral hydrate and hydroxyzine

The purpose of this study was to determine differences in heart rate (HR), blood pressure (BP), peripheral gen saturation (p02), expired 2 (C02), an d behavior (using two scales) comparing nitrous oxide~oxygen (N20) with oxygen (02) alone in 20 children (mean age + 5.1 months) sedated with chloral hydrate (CH) and hydroxyzine in a double-blind crossover design. Administration of CH (40 mg/kg) and hydroxyzine (2 mg/kg) was constant for each patient visit; however, N20 (50%) was administered during one visit and 02 (100%) at the other in a randomly determined manner. Physiologic and behavioral parameters were collected during eight specific procedural events (e.g., administration of local anesthesia). Data were analyzed with a repeated-measures ANOVA, one-way ANOVA, t-test, Kruskal Wallis ANOVA, and descriptive statistics. There was no statistically sign~’cant difference in any physiologic or behavioral parameter as a function of inhalation agent. However, significant differences were found for certain physiological parameters (i.e., HR IF = 5.41, P < 0.0011, pO 2 [F = 6.04, P < 0.001], and CO 2 [F = 2.33, P < 0.027]) and all behavioral measures (% crying [F = 2.82, P < 0.008], % quiet [F = 5.38, P 0.001], % movement [F = 3.88, P < 0.001], and % struggle IF = 2.83, P < 0.007]) of one scale (Ohio State University Behavioral Rating Scale [OS UBRS]) as a function of procedural events. Although no statistically significant differences were attributable to inhalation agent, evidence suggests that N20 resulted in less crying and struggling and more quiet behaviors than 02. Significant correlations existed between sub-categories of the two behavioral rating scales, suggesting some association between the scales. One may conclude from the results of this study that moderate doses of CH and hydroxyzine in combination with nitrous oxide are not associated with any significant potentiation effects on physiologic parameters compared with the same oral agents with oxygen alone. Certain procedural events (e.g., administration of local anesthesia) do result in patient responses that affect specific behaviors and physiology. Although the effects of N20 may not be statistically significant, generally it produces an attenuation in physiological and behavioral responses as measured under the conditions of this study. (Pediatr Dent 18:35-41, 1996)