329

Australian Dental Journal, October,1979 Volume 24, No. 5

Sedation for dental treatment of infants. II. CIinical procedure Robin Woods

ABSTRACT-The details of a clinical technique for sedation and treatment of young children, using a narcotic premedication, and a nitrous oxide-oxygen technique with local anaesthesia is described.

Introduction The use of either a dependable form of sedation or general anaesthesia is necessary to enable dental treatment for some children with the least stress possible for the patient. The technique is one of clinical sedation augmented by premedication and local anaesthesia. Children needing sedation for dental treatment are usually less than three years of age, and some older children whose anxiety may preclude them from receiving dental treatment without sedation. The physiological basis of sedation and an outline of the relevant neurophysiology and pharmacology have been presented.' Langa has described2 the second plane of analgesia in which the patient remains conscious, responds to verbal requests but is relaxed and accepts treatment without undue stress. The technique to be described achieves this state by the correct use of long-established drugs administered in several stages. The limitations of these drugs are well known and employing them in stages offers several opportunities to suspend the procedure if an adverse, exaggerated, or unpredicted response occurs.

' Woods,

R.-Sedation for dental treatment of infants: 1. Physiology and pharmacology. Austral. D. J . , 24: 4, 213-

The technique relies on premedication consisting of an intramuscular injection of papaveretum and hyoscine* followed some 45 to 60 minutes by administration of nitrous oxide and oxygen, and a local anaesthetic. This report is based on experience using this technique for 85 young children. Their ages ranged from 19 months to eight years and ten months, the average age was five years and seven months. Their weight ranged from 11 to 26 kg, the average being 18.5 kg. Parents often seek treatment for their children following the discovery of a small carious lesion whilst cleaning their children's teeth. The dental treatment included restoration of carious fissures and proximal lesions and extraction of deciduous teeth; some first permanent molars were restored. Patient assessment In every case prior to treatment the child was examined and assessed at a separate appointment. The child's medical history was obtained from the parent. Four of the 85 children had a history of penicillin allergy; five had a history of chronic respiratory disease including bronchitis and asthma. The high prevalence of penicillin allergy in this group of young patients is similar to that

218 (Aug.) 1979.

Langa. H.-Relative analgesia in dental practice. Philadelphia, W. B. Saunders Company, 1958 (p. 42). G

* Omnopon-Scopolamine. Roche

Products Pty Ltd

330 reported elsewhere for patients of all ages3. This group of children may have received penicillin more frequently than other children of similar age. The child’s weight is recorded for calculation of drug dosages. The amount of treatment that can be rendered at a single appointment is limited by the maximum amount of local anaesthetic which can safely be used. When treatment is needed in three or four quadrants, several appointments are necessary for children who weigh less than 25 kg. Contraindications to treatment A history of allergy or hypersensitivity to any of the drugs to be used is an absolute contraindication. Allergies to local anaesthetics are rare but have been reported, allergies or hypersensitivities to narcotics occur in about 0.4per cent of the population. In the presence of any acute respiratory disorder, colds, influenza, or other respiratory tract infections, treatment should be postponed until the patient has recovered. A history of asthma is not itself a contraindication to treatment, although asthmatic patients may be taking medication including antihistamines which could potentiate the sedative used and also interact adversely with catecholamine vasoconstrictors. Preparation of child and parent

The parent and the child should as far as possible understand the nature of the proposed procedure; they can be prepared for the visit with a careful description, and can be told that although local anaesthetics will be injected they will not be felt and may not even be remembered. On arrival at the surgery a small injection will be given in the back of the leg. Early morning appointments are preferable, and the child should fast from the previous night. Loose, warm clothing should be worn. The parent will need assistance in driving the child home after treatment; to drive an automobile and to care for a sedated child seems a hazardous division of responsibility. The parent should also arrange for a light lunch; junket or custard is well tolerated after treatment. Clinical procedure Premedication On arrival the patient’s weight is checked and the child is made comfortable. Children can be easily occupied with jigsaw puzzles and colouring books, these activities can be observed from time to time, pre- and post-operatively, as a measure of psychomotor ability and recovery. Eggleston, D. J.-The value of a simple medical questionnaire in dentistry. Austral. D. J., 22: 3, 160-164 (June) 1977. Woods, R.-Pyogenic dental infections: A ten year review. Austral. D. J., 23: 1, 107-111 (Feb.) 1978.

Australian Dental Journal, October, 1979 Premedication with papaveretum and hyoscine has been found most reliable and effective; it causes less emesis and nausea than pethidine. It is the safest and most reliable narcotic available for children and its action is more predictable than either pethidine or pentazocine. TABLEI Papaveretum doses for premediration by body weight ( 0 . 3 mglkg) Dose

Body weight

(kg) 10 12 14 16 18 20 22 24 26 28 30

.. .. _. _. _. .. ..

.. .. ..

..

..

..

_.

..

..

..

_.

, _

.. ..

.. ..

..

..

..

.. ..

,.

..

..

..

._

3.6 4.2 4.8 5.4 6.0 6.6 7.2 7.8 8.4 9.0

Equivalent vol. of s o h ’

(ml) 0.15 0.18 0.20 0.25 0.27 0.30 0.33 0.35 0.40 0.43 0.45

* Papaveretum 20 mg/ml.

The dose used is papaveretum 0 . 3 mg per kg body weight, or calculated from the weight of papaveretum, and is half that recommended by the manufacturers. Papaveretum doses are set out in Table 1. It has been found that this injection can be given quickly and easily, using a short disposable 26 gauge hypodermic needle and syringe, in the back of the upper part of the leg in the long head of the biceps femoris muscle. This site is suggested as it cannot be seen by the child. The most serious adverse reaction likely is respiratory depression which could occur when the child is sitting quietly on the mother’s lap. The emergency treatment for that event is outlined later. Clinical sedation From 45 to 60 minutes after the premedication injection the child should be calm but awake, entering the first of Langa’s planes of analgesia. The child is usually carried to the surgery and placed in a semi-supine position, never horizontal. A rug is used to keep the child warm and to minimize oxygen use associated with heat loss. At this stage the pulse is usually in the range 90 to 110, blood pressure, systolic 90 to 110 and diastolic 50 to 60 mm mercury. The hyoscine given with the premedication tends to raise systolic blood pressure and pulse rate slightly. A parent is encouraged to remain in the surgery with the child to hold his hand which reassures the child and allows the parent to see exactly what is done.

331

Australian Dental Journal, October, 1979 TABLE 2 Moxtmum doses of local anaesthetics for infants by body weight

Prilocaine four per cent Plain

Body Weight

Dose

12 I4 16

.. ._ ..

18

..

20 22 24 26 28 30

.. .. .. .. .. ..

.. .. ..

70

..

104 1 I6

..

128 140 151 I62 174

.. .. ..

.. ..

81

93

Lignocaine two per cent with vasoconstrictor

Prilocaine three per cent with vasoconstrictor

Vol. of soh.

Dose

(ml) I .5 I .8 2.0 2.3 2.6 2.9 3.2 3.5 3.8 4. I 4.4

(mg) 86 103 120 137. I54 171 189 206 223 240 257

Using either a nasal mask, or for some young children a mask covering nose and mouth, a mixture of nitrous oxide and oxygen is administered. Initially the nitrous oxide concentration is relatively high ; approximately 60 per cent. The time from the beginning of administration of nitrous oxide should be measured, a stop watch is convenient. When a nasal mask is used the air valve is closed and the re-breathing or exhalation valve is adjusted to the position of least tension. Respiration needs constant monitoring either by chest movement, the breathing bag, or by a stethoscope placed just above the sternum. The rate should be approximately 15 to 25 per minute and should not be allowed to fall below 12 per minute. The pulse should be taken periodically since the rate usually falls slightly after the commencement of the nitrous oxide but generally not below 85 per minute. The carotid pulse is a convenient point to monitor. The high concentration of nitrous oxide is administered for five to seven minutes and the patient’s responses, especially to verbal directions, should be carefully observed. Even in these circumstances children hypersensitive to nitrous oxide may slip into a deeper state of sedation than desired, or even enter Guedel’s second stage of anaesthesia characterized, by restlessness, muscle spasm, and delirium. In such instances the child should be given pure oxygen until Guedel’s first stage is regained when nitrous oxide can be reintroduced, if necessary, but at much lower concentrations.

Local anaesthesia When the child is relaxed and established in the second of Langa’s planes of analgesia, able to respond to directions and maintain the mouth open, the local anaesthetic should be given. Local anaesthetic solutions with catecholamines are best avoided as catecholamines may stimulate the cerebral cortex causing irritation, anxiety, or restlessness,

Vol. of s o h .

Dose (mg) 12

3.4 4.0 4.6 5.I 5.7 6.3 6.9 7.4 8.0 8.6

86

101 I15 I30 144 158

173 I87 202 216

Vol. of s o h.

(ml)

3.6 4.3 5.I 5.8 6.5 7.2 7.9 8.7 9.4 10. I 10.8

antagonizing the effects of sedation. Prilocaine, four per cent? with no vasoconstrictor, or prilocaine three per cent with felypressinl are both effective and appropriate local anaesthetics. Using a topical anaesthetic and injecting the local anaesthetic slowly and with care, the injection often is not noticed. Aspiration should always be performed even at infiltration sites because of the increased risk of intravascular injection following use of nitrous oxide. The total amount of local anaesthetic used is critical especially for smaller children and is the factor which limits the amount of treatment which can be undertaken at one appointment. The maximum safe dose of local anaesthetic should be calculated from the child’s weight. Maximum doses by body weight of prilocaine and lignocaine are set out in Table 2. Where both prilocaine and lignocaine are used for the same patient the effect is cumulative and the maximum dose of each drug must be reduced proportionally. The maximum dose of local anaesthetic agents have been calculated on the following basis: prilocaine four per cent, 5.8 mg/kg body weight, prilocaine three per cent with a vasoconstrictor 8 . 6 mg/kg, and lignocaine two per cent with a vasoconstrictor 7 . 2 mg/kg. The vasoconstrictor present, by limiting the diffusion rate of the local anaesthetic, reduces its toxicity. If the solution is accidentally deposited intravenously its toxicity is doubled. For infiltration, 1 ml of anaesthetic solution is adequate for each deciduous tooth to be restored; for mandibular block injections 1 ‘ 5 to 2 . 0 ml of prilocaine four per cent is sufficient. Although prilocaine plain or with felypressin is the anaesthetic of choice where deciduous extractions are

t Citanest IS. Astra Pharmaceuticals.

1 Citanest Octaprmin.

Astra Pharmaceuticals

332 needed, in addition a small amount of local anaesthetic with a catecholamin4 is useful to help control bleeding. Neither lingual nor palatal injections are necessary. Any dose of local anaesthetic used for children is comparatively large in relation to body weight. After the local anaesthetic is given there is often a transient lowering of blood pressure and an apparent deepening of the level of sedation. The reason for this phenomenon is not understood; it may be the effect of the local anaesthetic itself or be due to a significant area of analgesia and subsequent diminished stimulation of the cerebral cortex. When the local anaesthetic has been administered, the level of nitrous oxide can be reduced to less than 20 per cent and often, after a few minutes, suspended completely leaving the child receiving only pure oxygen.

Operative procedure Local anaesthesia takes about four minutes to become established. At this time the child is able to keep its mouth open and operative procedures can be performed gently and without any urgency. Where water cooling is used, the airway should be protected as much as possible from the water aerosol. Water should never be allowed to accumulate in the child’s mouth, it creates distress by threatening the child’s airway, and is a considerable danger. For the very young child cavity preparations often can be made without water cooling. After operative treatment is finished, the child remains in the surgery and is given pure oxygen for five to ten minutes by which time he is fully awake although some signs of the premedication may remain. During this period the child is often given z prophylaxis and topical fluoride application. Recovery The child is carried to the waiting room for recovery where he is nursed by the parent and kept warm. Sometimes the child sleeps lightly in this position free of the stress of clinical procedures. After approximately 20 minutes the child usually resumes its puzzles or colouring, observation of which can be used to assess recovery and the return of psychomotor ability. Where a child is given insufficient time to exhale nitrous oxide by reducing the post operative period with pure oxygen, or if prevented from having a short sleep post-operatively, a period of cerebral irritation may occur. This is characterized by irritability and can be avoided with adequate post-operative oxygen and a short post-operative sleep.

Australian Dental Journal, October, 1979

Complications The art is to avoid emergencies rather than to treat them. A medical history should always be taken and assessed with respect to the proposed procedures. Potent drugs should always be administered slowly and carefully, and reactions, especially respiration, should be constantly monitored. Hypersensitivity reactions lead to exaggerated and sometimes dangerously increased responses. Narcotic hypersensitivity could lead to respiratory depression, a serious potential hazard. Because the recommended dose of papaveretum is small a complication from this source is unlikely. Emergency equipment Efficient and reliable suction is essential where this technique is practised. Aspiration equipment conforming to the appropriate standards7 and a means of determining arterial blood pressure should always be available. A proper child cuff for a sphygmomanometer is essential. The stethoscope needed for determining blood pressure can also be used to listen to respiration and heart beat. Oxygen under pressure is available from the nitrous oxide-oxygen machine, proper valves and masks to enable its use for ventilation must be available. A list ofdrugs and apparatus which should be available where sedation is performed is included in a report currently being circulated for discussion.

Respiratory depression Even using the low dose of papaveretum recommended respiratory depression is a possibility. It could occur as a result of airway blockage if a patient is accidentally allowed to enter the third of Guedel’s stages of anaesthesia. Initially respiratory depression is manifested by slow or shallow, sometimes audible respiration, and cyanosis, even mild, is a late sign. If respiratory depression is detected immediately ventilate the patient with pure oxygen. In the early stages this may be sufficient, however, if respiratory depression persists and a narcotic has been used, a narcotic antagonist should be injected and ventilation with oxygen continued until the antagonist becomes effective. Nalorphine hydrobromide,I I administered intramuscularly in a dose based on the child’s weight, followed, if there is no response in 10 to 15 minutes, by a second dose, should be used. Table 3 sets out doses at 0.15 mg/kg body weight for nalorphine hydrobromide.

7 British Standard BS4199, an Australian standard is being prepared. In addition attachments for pharyngeal suction should be available. I1 LaMdmne. Burroughs Wellmme.

5 cTt.aat 30. Astra Pharmaceuticals. Narocabe with Aircl.lhe. Glover. NeProair witL SylytLL. Glover. X y l o a k with Adredhe. Astra Pharmaceuticals XyMox Eplaepbriae. Dental Distributors.

Report of a committee investigating the use of intravenous sedation, relative analgesia and general anaesthesia in dental practice. Sydney, Health Commission of New South Wales, November 17, 1977.

333

Australian Dental Journal, October, 1979 Artificial ventilation with pure oxygen should continue until spontaneous breathing is established. Respiratory depression, undetected and untreated, will lead to grave complications; myocardial hypoxia and cardiac arrest are likely. TABLE3 Doses of nalorphine hydrobromide by body weight ( 0 . 1 5 mglkgl Body weight (kg) 10

12 14 16 18

20 22 24 26 28 30

. . . . . . . . . . . . . . ..

. . . . .

.

Dose

Vol. of soh' (mi)

. . . . .

. . . . .

. . . . .

. . . . , _ ,.

. . . . . . . . . . . . . . . . . .

0.15

I .8 2. I 2.4 2.7 3.0 3.3 3.6 3.9 4.2 4.5

0.18 0.21 0.24 0.27 0.30 0.33 0.36 0.39 0.42 0.45

* Nalorphine hydrobromide 10 mg/ml. Methaemoglobinaemia Methaemoglobinaemia may arise from an excessive dose of prilocaine. The condition limits the ability of the haemoglobin to convey oxygen and could be a serious complication where children have anaemia. In these circumstances hypoxia may occur leading to other complications. Immediate treatment is by administration of pure oxygen. The condition does not readily resolve. Medical assistance should be sought and the patient should be admitted to hospital for observation until the symptoms disappear. Orthodox treatment is with methylene blue given by mouth; the dose for a 20 kg child is 75 mg daily, in divided doses. Ascorbic acid6 has been suggested, used either with, or as an alternative to, methylene blue; a child dose of 200 mg every six hours by mouth or 50 mg every six hours by intramuscular injection is recommended. Medication may be commenced on admission Martindale.-The extra pharmacopoeia. Edit. Blacow, N. W., London. The Pharmaceutical Press, 26th edn, 1972 (p. 405).

to hospital although oxygen therapy and observation may be all that is needed. Evaluation The assessment of this type of treatment by other than subjective observation of effectiveness and safety is not possible. It was possible to treat all patients, whatever age, using the technique described. No patient resisted treatment, all were co-operative; neither the patients nor the parents accompanying them showed any signs of distress while treatment was taking place. Only one child resisted a prophylaxis and topical fluoride treatment at a subsequent visit. By thesecriteria, especially having regard for the ages of the children, the technique is considered successful. Summary An advanced procedure for safe and effective clinical sedation of infants and young children has been described. It employs a combination of well-known drugs whose limitations and effects have been long established. Because the drugs are given in stages procedures can be terminated should adverse reactions occur without committing the patient to the full regimen. This is an excellent means of introducing young patients and their parents to a regular preventive dentistry programme which should be part of a comprehensive treatment plan. The presence of a parent helps establish an understanding between dentist, child, and parent. No attempt has been made to describe the details of nitrous oxide and oxygen sedation (relative analgesia) there is ample information elsewhere.2 The procedure described is an advanced technique and should not be attempted until a practitioner is expert in the clinical aspects of sedation and the relevent physiology and pharmacology. It is hoped that the understanding and careful use of the technique described will assist young patients to obtain the dental treatment they need free from fear and that this will help them achieve a good start to good dental health. P.O.Box 22, Yass, N.S.W., 2582.

Sedation for dental treatment of infants. II. Clinical procedure.

329 Australian Dental Journal, October,1979 Volume 24, No. 5 Sedation for dental treatment of infants. II. CIinical procedure Robin Woods ABSTRACT-...
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