Effects of Nitrous Oxide on Chloralhydrate Sedation of Young

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 treatment 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 compared 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. Subjects receiving nitrous and disoriented and in 33% of the time, subjects were oxide cried less during the first part of the appoint- fully awake. Most of the time that subjects were ment when the mouth prop was inserted and the awake occurred at the beginning of the procedure injections were performed (P < .05, T = 42.5 for 17 within the first 15 minutes of being in the operatory differences). During the second half of the appoint- when the mouth prop was placed, the injection was ments, there was little benefit of the nitrous oxide in administered and the rubber dam was applied. regard to crying. Evaluation of Movement Overall Evaluations The means of ratings of movement for all subjects Overall evaluations were made of the periods be- at the various times of evaluation are illustrated in fore and after change of the gas from 100% oxygen to Figure 2. For subjects receiving nitrous oxide, the nitrous oxide or the reverse. A separate rating scale mean ratings at the five periods of observation were 3.55, 3.30, 3.25, 3.55, and 3.75, and the range of ratings at all periods was 1 to 4. For subjects receiving only oxygen the mean ratings were 3.05, 2.25, No Crying 4 3.20, 3.60 and 3.65, and the range similarly was 1 to 4. In most instances, subjects exhibited no move- Intermittent 3 ment or minimum controllable movement that did not Gas interfere with the procedure. Subjects receiving ni- Continuous 2 - Change trous oxide moved slightly less when the mouth prop was inserted and the injection was performed com- Hysteriew 1 ..... With Nitrous Oxide pared with those same procedures without nitrous - Withou Ntous Oxide oxide (P <.05, T = 39.5 for 1 7 differences); however, I I there were few differences when treatment was per- Mouh Injetion 60 Min 75 Min. 90 Min. formed. Nitrous oxide demonstrated greater benefit Prop during the early as compared with the latter part of the Fig. 3 - Evaluation of crying. Ratings are parallel to ratings in appointment. Figure 2.

300 ANESTHESIA PROGRESS for overall behavior (Table 4) which combined the For example, the pulse spiked from 100 to 180 on scales for crying and movement was used and the occasion when the mouth prop was inserted, when results of the evaluation are illustrated in Figure 4. local anesthesia was given, or when the rubber dam Most subjects demonstrated good, very good or ex- was being applied. The increase in pulse rate was cellent effects of the sedation; however, 16% of the transitory and quickly returned to normal when the time the overall evaluation was less than good and stimulus ended. In regard to respiratory rate, treatment had to be interrupted. Using the overall changes (for example, from 25 to 40) occurred simi- evaluations, the effect of the nitrous oxide was com- larly at a time of particular stimulus. Constriction of pared with the effect of 100% oxygen. Overall, the the pupils was found to be related to the patient's nitrous oxide augmented the sedation in 23 of 40 degree of sleep in that when the patient was asleep treatment sessions, however, it had little or no effect the pupils were constricted with little reaction to light. in the remaining 17 sessions. Of the 23 sessions in When the patient was awake, the pupils were normal which the nitrous oxide increased the effect of the and reacted to light; however, whenever a patient chloral hydrate, 8 occurred during first appointments became excited, the pupils were dilated and reactive with the remainder during the second appointments. to light. Although the nitrous oxide was beneficial for some Following depression of the mandible in order to patients, it was not uniformly beneficial for all pa- test depth of sedation, the patient responded within 5 tients. seconds in 70% of the tests with nitrous oxide and 73% of the tests without nitrous oxide. In the remain- Vital Signs der of the tests, the patients did not respond when the There were few changes in the vital signs through- mandible was depressed for 15 seconds. out the procedures. Blood pressure remained essentially unchanged and pulse rate exhibited transitory, Adverse Effects although dramatic, increases which were linked to Two subjects coughed up small amounts of fluid specific occurrences when the child was stimulated. when their throats were suctioned and one spit up slightly at the end of treatment; otherwise vomiting or respiratory depression was not evident during this TABLE 4 Rating Scale for Overall Behavior study. Score Discussion Aborted - no treatment rendered 1 Poor - treatment interrupted, only The results of this study indicate that in regard to partial treatment completed 2 the control of behavior, the use of nitrous oxide improved the sedative effects of chloral hydrate in Fair - treatment interrupted, but slightly more than half of the administrations, eventually all completed 3 whereas in the remainder of the administrations be- Good - difficult, but all havior was not improved. Since it was expected to treatment performed - 4 find that the chloral hydrate sedation would be aug- Very good - some limited crying mented by the nitrous oxide, it was surprising to find or movement; e.g. during that this was not uniformly the case with all patients. anesthesia or mouth prop insertion However, the combination of nitrous oxide with 5 chloral hydrate is not used to produce general anes- Excellent - no crying or movement - 6 thesia and it is quite possible that the behavior of some children was sufficiently poor so as not to be managed by conscious sedation. 1InQ ICA - 1nliw-Oiw U...,#- When the nitrous oxide augmented the sedation, 1 the effect was greatest during the first part of the treatment session when stimuli were greater; e.g., C2 during mouth prop insertion, local anesthesia and 0I rubber dam placement. The lack of a greater difference in sedation with and without nitrous oxide during the second part of the session might have been due E lo the lack of strong stimuli. It might also have been z caused by exhaustion of the child following crying during the first part of the appointment, yielding increased sedative effect without the benefit of the 1 2 3 4 5 6 nitrous oxide. Aborted Poor Fair Good Very Excellent During this study, the Papoose Board with auxiliary Good head restraint was used, and this device tremen- Fig. 4 - Overall evaluation of sedation. dously restricted movement. Insofar as one of the

NOVEMBER/DECEMBER 1986 301 measures of success of sedation was movement, the success be carefully defined when researchers com- use of this device could explain the relatively good pare the results of clinical studies and when clinicians results of the sedation. These results were somewhat compare the effects of different drug regimens. better than those obtained by Houpt, et al.5 in a study In a search for measures of depth of sedation, of chloral hydrate. In that study, however, the head Moore, et al.7 suggested that bending the neck so restraint connected to the Papoose Board was not that the chin touched the chest causing airway used and this might have accounted for the lack of obstruction might be a satisfactory index whereby a effectiveness of the sedation due to the movement of lack of response might be an indication of excessive the child. It appears that there is a distinct advantage depth of sedation. In this study when the mandible to using the special supplemental head holder at- was depressed to obstruct the airway, lack of re- tached to the Papoose Board in that not only does the sponse occurred in about one quarterof the time both head restraint prevent some undesirable movement, with and without nitrous oxide and it did not seem to but it also facilitates the delivery of nitrous oxide by be related to the depth of sedation. During this study, keeping the nasal hood directly over the nose. respiration was monitored at two sources-by re- Success of sedation was defined as lack of crying cording movement of the chest and by recording air or movement which interrupted treatment and this exchange through the nasal inhaler (Figure 5). The occurred in 84% of administrations. These included air exchange measure demonstrated that when the sedation with an overall rating of good (difficult, but all mandible was depressed, there were occasions treatment performed). If this group of sedations was when the airway was not completely obstructed and, considered as unsuccessful (that is, although treat- consequently, it is possible that there was not suffi- ment was not interrupted, there was too much crying cient obstruction to disturb those individuals who did or movement to be considered successful sedation), not respond with the mandibular depression test. then only 53% of administrations would be success- Furthermore, it is also possible that 15 seconds is too ful. If practitioners would expect that chloral hydrate short a time to properly test the depth of sedation, in supplemented with nitrous oxide produced a child that the airway is not sufficiently compromised to with little or no crying, they would be disappointed to elicit a response in that period of time. find that in almost half the time that criterion was not From the results of this study, it may be concluded achieved. It is particularly important that criteria for that nitrous oxide augments the effect of chloral hydrate sedation of young children; however, it does not do so uniformly for all children receiving sedation. References 1. Duncan WK, Ashrafi MH, Pruhs RJ, Post AC: Chloral hydrate and other drugs used in sedating young children: a survey of American Academy of Pedodontic Diplomates. Ped Dent 5:252-256, 1983. 2. Barr ES, Wynn RL, Spedding RH: Oral premedication for the problem child: placebo and chloral hydrate. J Pedo 1:272-280, 1977. 3. Smith RC: Chloral hydrate sedation for handicapped children: a double blind study. Anesth Prog 24:159-168, 1979. 4. Robbins MB: Chloral hydrate and promethazine as premedi- cants for the apprehensive child. J Dent Child 34:327-331, 1967. 5. Houpt Ml, Koenigsberg SR, Weiss NJ, Desjardins PJ: Com- parison of chloral hydrate with and without promethazine in the sedation of young children. Ped Dent 7:41-46, March 1985. 6. Sim JM: Chloral hydrate in Behavior Management in Dentistry for Children, Wright, GZ, ed. Philadelphia; W.B. Saunders Company, 1975, pp. 165-69. Fig. 5 -Respiration monitored by gas exchange through the nose 7. Houpt Ml: Report of Project USAP-The use of sedative agents (top channel) and by movements of the chest (lower by pediatric dentists. Ped Dent 8:175, June 1986. channel). Note that when the mandible was depressed 8. Moore PA, Mickey EA, Hargreaves JA, Needleman HL: Seda- gas exchange was partially but not completely tion in pediatric dentistry: a practical assessment procedure. obstructed, and chest movements were unchanged. JADA 109:564-569, October 1984.

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