SCIENTIFIC ARTICLES Effects Of Nitrous Oxide On Chloral Hydrate Sedation Of Young Children Milton 1. Houpt, D.D.S., Ph.D., R. Glenn Rosivack, D.D.S., Nathan Rozenfarb, Dr. Odont., Samuel R. Koenigsberg, D.M.D., M.S. Department of Pediatric Dentistry, University of Medicine & Dentistry of New Jersey, New Jersey Dental School Summary This study was performed to test the hypothesis that nitrous oxide augments the effects of chloral hydrate sedation of young children. Twenty children with a mean age of 32 months were sedated on two occasions with two different treatment regimens. All subjects received a standard dose of 50 mg/kg of chloral hydrate with or without nitrous oxide dunng each of two treatment visits. During one visit, the subjects received 50% nitrous oxide and 50% oxygen for a period of 20 minutes followed by 100% oxygen and, dunng the other visit, the reverse concentrations were used. All subjects were restrained in a Papoose Board* with an auxiliary head restraint. Successful sedation, as evident by lack of crying or movement which interrupted treatment, occurred in 84% of administrations. During the first twenty minutes, subjects receiving nitrous oxide moved and cried significantly less than when they were treated without nitrous oxide. During the remainder of the appointment, there was no difference in behavior between the two treatment regimens. Vital signs remained essentially unchanged throughout all treatment with the exception of transitory elevation of the pulse and respiratory rates, which usually occurred when the mouth prop was inserted and local anesthesia was administered. It is concluded that nitrous oxide augments the effect of chloral hydrate sedation of young children, but does not do so uniformly for all children receiving sedation. Sedation frequently is used when comprehensive the child be in good health, that two restorative den- treatment is performed for very young children. Orally tistry appointments were required, and that sedation administered chloral hydrate is used because of its was necessary in order to manage uncooperative wide margin of safety and relatively few adverse behavior as determined in a screening examination. effects."A However, there has been little research to substantiate the effect of nitrous oxide on chloral Medications hydrate sedation. All subjects received the manufacturer's recom- This study was conducted in order to test the mended standard dose of 50 mg/kg of chloral hydrate hypothesis that nitrous oxide would augment the ef- (Noctec®)** for both treatment visits. At the first ap- fects of chloral hydrate when used to sedate young pointment, the subjects were randomly assigned to children for dental treatment. receive either regimen A or B for the first appointment with the alternate regimen administered during the Method second appointment. Consequently, a crossover de- sign was used with each subject serving as its own Subjects control and the 20 subjects participated in 40 treat- Twenty children ranging in age from 23 to 46 ment sessions. Treatment regimen A consisted of months with a mean age of 31.8 months participated 50% nitrous oxide and 50% oxygen for the first 20 in the study. Requirements for participation were that minutes of treatment followed by 100% oxygen for the remainder of the appointment, which was usually 40-60 minutes. Treatment regimen B consisted of 1 00% oxygen forthe first 20 minutes followed by 50% Accepted for publication November 13, 1986. Address correspondence to Dr. Milton Houpt, Professor and Chairman, Department of Pediatric Dentistry, New Jersey Dental *Olympic Medical Group, Seattle, WA School, 100 Bergen Street, Newark, New Jersey 07103. **E.R. Squibb and Company, Princeton, N.J. 298 ANESTHESIA PROGRESS nitrous oxide and 50% oxygen. In addition, during the havioral rating was a summary of behavior exhibited treatment procedure, all children were restrained in a since the previous rating. Both the operator and the Papoose Board with auxiliary head restraint. Sub- independent observer were kept blind as to whether jects were without food or fluids for at least 8 hours. the patient received nitrous oxide or 100% oxygen, Following their arrival, the vital signs and behavior and a third individuat made all settings to the nitrous were evaluated. Chloral hydrate was then adminis- oxide machine, which was kept covered. A consen- tered and on 30 occasions the child was coaxed into sus rating was made by two investigators (M.H. and drinking the chloral hydrate solution. In the remaining S.K.) from videotapes of the procedures to verify the 10, the solution was administered orally with a reliability of the rating scales, which had been previ- syringe. The dosages of chloral hydrate ranged from ously established.5 565 mg to 955 mg with a mean of 867 mg. The child In the operatory, blood pressure, pulse and respi- then remained with the parent for 45 minutes during ration were recorded with the use of a Beckman which time the onset of sleep was checked every 5 R51 1-A polygraph unit. Pulse was measured from minutes. After 45 minutes the child was transferred to the subject's index finger, respiration was recorded the operatory for the start of treatment. from an abdominal pneumatic belt measuring movements of the diaphragm, and a transducer Evaluation mounted on the reservoir bag was used to monitor The degree of sleep, body movements, crying, exchange gases through the nose. A precordial blood pressure, pulse, respiration rate and pupil size stethescope was also used to monitor respiration. were evaluated before, during and after operative Figure 1 shows sample recordings of blood pressure, procedures. In the operatory, these variables were pulse, chest movements, and gas exchange through rated by an independent observer during mouth prop the nose. insertion, administration of local anesthesia, place- As a separate part of this study, there was an ment of rubber dam, and every 15 minutes thereafter attempt to corroborate the findings of Moore, et al.7 using separate rating scales (Tables 1-3). Each be- using airway obstruction to test the depth of sedation. The mandible was depressed for a maximum of 15 seconds to close the airway until the patient demon- TABLE 1 Rating Scale for Sleep strated some movement. This test was performed on two occasions during the first and second parts of Score treatment, except when the patient was obviously Fully awake, alert 1 awake. It was performed after the 60 minute be- Drowsy, disoriented 2 havioral ratings and before the gas change, and it Asleep 3 was performed after the 75 minute rating which was after the gas change. TABLE 2 Rating Scale for Movement Score ........ ., Violent movement that ...........,i .;, .; (,:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~... ... interrupts treatment 1 Continuous movement that makes treatment difficult 2 Controllable movement that does not interfere with treatment 3 No movement 4 TABLE 3 Rating Scale for Crying Score Hysterical crying that interrupts treatment 1 Continuous, persistent crying that makes treat- ment difficult 2 Fig. 1 - Sample recordings of vital signs. Top channel records blood pressure intermittently, and the next channel dis- Intermittent, mild crying plays pulse continuously. (Note that the pulse record that does not interfere disappears as the blood pressure cuff is inflated, reduc- with treatment 3 ing the blood flow through the finger monitor.) The next No crying 4 two channels indicate respiration as monitored by gas exchange through the nose and by chest movements. NOVEMBER/DECEMBER 1986 299 Data Analysis No This experiment was designed so that each sub- Movement 4 ject could serve as its own control with the same time ..*~~~~~.06 of day, the same operator and similar types of proce- SlIght 3 dures during both treatment sessions. The indepen- Gas dent variable was the use of nitrous oxide and the Contnuous 2 - Chang dependent variable was the effectiveness of chloral hydrate sedation as measured the of by degree cry- Vbbnt 1 I With Nitrous Oxide ing and movement which interfered with treatment. - Wihout Nitrous Oxide Since the rating scales used the ordinal scale of measurement with related samples, the nonparamet- Mth Injeion 60 Mi 75 Min. 90 Min. ric sign rank test was used to compare the groups for PMp statistically significant differences. Fig. 2 - Evaluation of movement. Mean ratings are shown for subjects receiving nitrous oxide compared with subjects not receiving nitrous oxide at each of five periods of Results observation. Note that subjects receiving regimen A are represented by the solid line before the gas change and Rater Reliability by the broken line after the gas change. When the ratings made in the operatory were com- pared with the ratings made from videotapes, 300 Evaluation of Crying ratings were identical, 83 differed by one scale point Figure 3 shows the means of ratings of crying for all and 11 differed by two scale points producing 76% subjects at the various times of evaluation. For sub- agreement between the sets of ratings. jects receiving nitrous oxide the mean ratings at the five periods of observation were 3.15, 3.05, 2.95, Evaluation of Sleep 3.50, and 3.75, and the range of ratings at all periods Of the 40 treatment sessions, on 16 occasions was 1 to 4. For subjects receiving only oxygen, the patients fell asleep in the waiting area after an aver- mean ratings were 2.90, 2.25, 2.95, 3.40 and 3.40, age of 20 minutes; in the remaining 24 treatment and the range similarly was 1 to 4. Most subjects sessions, patients were awake when brought into the exhibited either no crying or occasional mild intermit- operatory. In 43% of the occasions that sleep was tent crying that did not interfere with the procedures. evaluated during treatment, all subjects were alseep. However, in 30% of the time, continuous persistent However, in 24% of the time, subjects were drowsy crying was exhibited.