Reevaluation of rectal ketamine premedication in children: comparison with rectal midazolam

BACKGROUND: Results of previous studies of rectal ketamine as a pediatric premedication are clouded because of lack of dose-response relation, inappropriate time of assessing sedative effects, and previous administration or coadministration of benzodiazepines. Therefore, the authors reevaluated the efficacy of rectally administered ketamine in comparison with 1 mg/kg rectal midazolam. METHODS: Sixty-six infants and children (age, 7-61 months) who were American Society of Anesthesiologists physical status I and who were undergoing minor surgeries as in-patients were randomized to receive 5 mg/kg ketamine (n = 16), 7 mg/kg ketamine (n = 16), 10 mg/kg ketamine (n = 17), or 1 mg/kg midazolam (n = 17) via rectum. A blinded observer scored sedation 45 min and 15 min after administration of ketamine and midazolam, respectively, when children were separated from parent(s) for inhalational induction. All children underwent standardized general anesthesia with sevoflurane, nitrous oxide, and oxygen with endotracheal intubation. Blood pressure, heart rate, and oxyhemoglobin saturation were determined before, during, and after anesthesia. Postoperative recovery characteristics and incidence of adverse reactions were also assessed. RESULTS: Most children (88%) who received rectally 10 mg/kg ketamine or 1 mg/kg midazolam separated easily from their parents compared with those (31%) who received 7 or 5 mg/kg rectal ketamine (P < 0.05). Similarly, more children who received 10 mg/kg ketamine or 1 mg/kg midazolam underwent mask induction without struggling or crying compared with those who received 7 or 5 mg/kg ketamine (P < 0.05). There were no clinically significant changes in blood pressure, heart rate, and oxyhemoglobin saturation after administration of either drug. Immediately after surgery, more children receiving midazolam or 5 mg/kg ketamine were agitated compared with 7 or 10 mg/kg ketamine. Ketamine, 7 and 10 mg/kg, provided postoperative analgesia, but the largest dose of ketamine was associated with delayed emergence from general anesthesia. CONCLUSIONS: The results indicate that rectally administered ketamine alone produces dose-dependent sedative effects in children, when evaluated at its predicted peak plasma concentration. Ketamine, 10 mg/kg, has a delayed onset but is as effective as 1 mg/kg midazolam for sedating healthy children before general anesthesia. However, 10 mg/kg rectal ketamine is not recommended for brief surgeries because of prolonged postoperative sedation.     

Midazolam and ketamine for rectal premedication and induction of anesthesia in children

Fifteen healthy children 2-10 years old and scheduled for elective surgery, received midazolam 0.35 mg/kg body weight and atropine 0.025 mg/kg as rectal premedication about 35 min before the induction of anesthesia. The induction itself was carried out in a separate and quiet room next to the operating theatre by rectal administration of ketamine 10 mg/kg and midazolam 0.2 mg/kg. With the children breathing spontaneously, anesthesia was maintained by repetitive i.v. bolus injections of ketamine. The sedative and anticholinergic effects of the premedication were satisfactory. Induction of anesthesia was smooth. Consciousness was lost after 9-15 (mean 13) min. No significant adverse effects on hemodynamics or respiration were noted. Recovery from anesthesia was uneventful. No cases of rectal irritation or unpleasant dreams were reported. Post-operative analgesia was good. In conclusion, rectal administration of midazolam and atropine for premedication, followed by ketamine and midazolam for the induction of anesthesia, proved to be a pleasant, safe, and reliable method in pediatric anesthesia.     

Rectal administration of midazolam versus diazepam for preanesthetic sedation in children

Sixty children were included in the trial. Each subject received midazolam 0.4 mg/kg body weight of diazepam 0.75 mg/kg body weight rectally in a double-blind randomized order. The degree of sedation of the children was assessed on arrival in the operating unit and during the induction of anesthesia. Adequate sedation on arrival in the operating unit and during induction of anesthesia was obtained in 84% and 67%, respectively, following administration of midazolam compared with 80% and 70% in the diazepam group. No side effects were noted. It is concluded that rectally administered midazolam 0.4 mg/kg is comparable to diazepam 0.75 mg/kg with respect to preanesthetic sedation in children.     

S(+)-ketamine for rectal premedication in children

Our purpose for this prospective, randomized, and double-blinded study was to evaluate the anesthetic efficacy of S(+)-ketamine, an enantiomer of racemic ketamine, compared with a combination of S(+)-ketamine and midazolam, and plain midazolam for rectal premedication in pediatric anesthesia. Sixty-two children, ASA physical status I and II, scheduled for minor surgery, were randomly assigned to be given rectally one of the following: 1.5 mg/kg preservative-free S(+)-ketamine, a combination of 0.75 mg/kg preservative-free S(+)-ketamine and 0.75 mg/kg midazolam, or 0.75 mg/kg midazolam. Preoperative anesthetic efficacy was graded during a period of 20 min by using a five-point scale from 1 = awake to 5 = asleep. Tolerance during anesthesia induction via face mask was graded by using a four-point scale from 1 = very good to 4 = bad. A sufficient anesthetic level (> or = 3) after rectal premedication was reached in 86% in midazolam/S(+)-ketamine premedicated children, in 75% in midazolam premedicated children, but only in 30% in S(+)-ketamine premedicated children (P < 0.05 S(+)-ketamine versus midazolam/S(+)-ketamine and midazolam groups). The incidence of side effects after rectal premedication was rare. Whereas the mask acceptance score was comparable in the three study groups, a 25% rate of complications during anesthesia induction via face was observed in the S(+)-ketamine study group (P < 0.05 versus other study groups). Our conclusions are that S(+)-ketamine for rectal premedication in the dose we chose shows a poor anesthetic effect and a frequent incidence of side effects during induction of anesthesia via face mask compared with the combination of midazolam/S(+)-ketamine and plain midazolam. Dose-response studies of S(+)-ketamine for rectal premedication in pediatric anesthesia may be warranted.     

Preinduction of anesthesia in children with rectally administered midazolam

The authors evaluated the efficacy of rectally administered midazolam for preinduction (i.e., premedication/induction) of anesthesia in 67 pediatric patients, ASA physical status 1 or 2, undergoing a variety of elective surgical procedures. In phase 1, 41 children weighing 12 +/- 3 kg (range 7-20 kg) and 31 +/- 16 months (range 8-67 months) of age (mean +/- SD) received midazolam, 0.4-5.0 mg.kg-1, in an attempt to produce unconsciousness. Only one child lost consciousness (4.5 mg.kg-1). However, at all doses, inhalational induction of anesthesia was facilitated because children were tranquil and calmly separated from their parent(s). There were no clinically significant changes in arterial blood pressure, heart rate, oxyhemoglobin saturation, and end-tidal carbon dioxide concentration, 10 min after drug administration. In phase 2, 26 children weighing 17 +/- 4 kg (range 10-26 kg) and 44 +/- 19 months (range 17-84 months) months of age undergoing tonsil and/or adenoid surgery were studied to determine the optimal sedative dose of rectally administered midazolam. Patients received 0.3, 1.0, 2.0, or 3.0 mg.kg-1 of midazolam in a randomized, double-blind fashion. One third (3 of 9) of patients receiving 0.3 mg.kg-1 struggled during mask induction. All patients receiving greater than or equal to 1.0 mg.kg-1 were adequately sedated (P less than 0.008). Discharge from the postanesthesia care unit (PACU), however, was delayed (greater than 60 min) in children receiving greater than or equal to 2.0 mg.kg-1 (P less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)     

Intranasal sufentanil/midazolam versus ketamine/midazolam for analgesia/sedation in the pediatric population prior to undergoing multiple dental extractions under general anesthesia: a prospective, double-blind, randomized comparison

This article details a double-blind, randomized study evaluating the efficacy and safety of intranasal sufentanil and intranasal midazolam (S/M) when compared with intranasal ketamine and intranasal midazolam (K/M) for sedation and analgesia in pediatric patients undergoing dental surgery. Fifty healthy ASA status 1 children aged 5-7 years, weighing 15-20 kg, and having 6 or more teeth extracted, were randomly allocated to 2 groups of 25 patients each (n = 50). In the S/M group, 25 children received intranasal sufentanil 20 microg, and intranasal midazolam 0.3 mg/kg 20 minutes before the induction of anesthesia. In the K/M group, 25 children received intranasal ketamine 5 mg/kg and intranasal midazolam 0.3 mg/kg 20 minutes before the induction of anesthesia. Sevoflurane in nitrous oxide and oxygen was used for induction and maintenance of anesthesia. This study demonstrated the safety and efficacy of both methods with ease of administration, combined with a rapid onset of action. Both groups were equally sedated. A smooth mask induction of anesthesia was experienced in the majority of children. Effective postoperative analgesia for multiple dental extractions was provided. The intranasal administration of drugs for sedation and analgesia has some promising features in preschool children undergoing multiple dental extractions.     

Serum potassium after enflurane-succinylcholine induction of anesthesia in children receiving rectal midazolam as premedication.

The administration of succinylcholine causes an increase in serum potassium (K+) concentrations in healthy patients. The purpose of this study was to investigate serum K+ changes following intravenous succinylcholine in children and to evaluate the effect of rectal midazolam pretreatment on these changes. Forty healthy children between the ages of 2 and 7 yr, and who were to undergo oral surgical procedures under general anesthesia were randomly assigned to receive either placebo (saline) or 0.25, 0.35, or 0.45 mg/kg midazolam administered rectally as premedication 30 min before induction of inhalational anesthesia. Blood was drawn after induction with enflurane and at 1, 2, 3, 4, and 5 min after administration of 1 mg/kg succinylcholine to determine changes in serum K+. Although the results indicate a significant increase in serum K+ after succinylcholine in all groups, midazolam pretreatment failed to cause any observable attenuation in the hyperkalemic response.     

Pharmacokinetic studies following intravenous and rectal administration of midazolam in children

In children, rectal midazolam is being used increasingly for premedication, as this substance is reported to have a short half-life and rapid action. Above all it is the only known diazepam derivative with a good correlation of plasma concentration and clinical action despite its receptor binding capacity. As pharmacokinetic data in children are lacking and different dose regimens for rectal premedication exist, we studied plasma concentrations in 3 groups of children. METHODS. After obtaining informed parental consent we studied children aged 3-7 years (15-30 kg body weight) ASA I status scheduled for minor elective surgery. Group 1 (n = 6) received 0.1 mg/kg midazolam i.v. for induction of anesthesia. Group 2 (n = 10) was premedicated with 0.35 mg/kg midazolam, instilled just behind the anal sphincter; group 3 (n = 5) received 0.5 mg/kg midazolam rectally. Blood samples were drawn up to 120 min after application. The anesthesia technique consisted of N2O/O2, enflurane, intubation and the use of muscle relaxants, if necessary. Midazolam plasma levels were measured by HPLC. RESULTS. There were no differences with respect to age or body weight. Group 1: half-life in children was shorter than in adults, Vdss was smaller and clearance identical. Group 2: Rectal midazolam 0.35 mg/kg has a remarkably short onset of action with peak plasma concentrations (71 ng/ml) in the range of sedative levels in adults occurring in 7.5 min. After 2 h they reached levels of 30 ng/ml. Group 3 patients had peak levels of midazolam of 246 ng/ml after 12.5 min, falling to an average concentration of 120 ng/ml after 2 h. The bioavailability of rectal midazolam, comparing the area under the median curves, is 4.7% in group 2 and 16.1% in group 3. CONCLUSIONS: The pharmacokinetics of midazolam in our patients showed a shorter half-life, probably due to the higher hepatic clearance based on the high CI in children, as midazolam is known to have a first-pass effect of 30-70%. The increased metabolic transformation and the smaller amount of fatty tissue accounts for the smaller Vdss in children compared to adults. Rectal midazolam has a remarkably short onset and especially in a dose of 0.5 mg/kg prolonged action due to ongoing resorption from the rectum as demonstrated by the clinically relevant plasma concentrations. This fact must be taken into consideration in the overall anesthesia management.(ABSTRACT TRUNCATED AT 400 WORDS)     

Rectal premedication in children

Two hundred and eight healthy children who were to undergo minor elective surgery during halothane, nitrous oxide, oxygen anaesthesia were studied in a double blind investigation to evaluate the sedative and anticholinergic effects of two rectal premedications. Group I received diazepam 0.75 mg/kg rectally; Group II received a mixture of diazepam 0.5 mg/kg, morphine 0.15 mg/kg and hyoscine 0.01 mg/kg rectally. No significant difference was found between the two groups in sedative or anticholinergic effects during induction of anaesthesia or in the postoperative period. No adverse effects were seen.     

Rectal administration of midazolam as an adjuvant in the premedication of infants

In a randomized, double-blind study of premedication in 69 infants aged between 13 and 48 months the effects of 0.82 mg/kg midazolam or diazepam rectally plus 2.0 mg/kg ketamine i.m., or the administration of 2.4 mg/kg ketamine i.m. alone was studied. A satisfying result of 94.1% following the premedication with midazolam/ketamine, of 82.9% with diazepam/ketamine and of 81.3% with ketamine alone was observed. Premedication with midazolam/ketamine was the best one in the review of vigilance, agitation, and behaviour of defence against the mask at the beginning of anaesthesia. The amnestic action of midazolam extinguished the infants' memory of the i.m.-injection. The dose of midazolam/ketamine is suitable as an effective and positive method for premedication of infants within 20 min.     

Lytic cocktail in children Rectal versus intramuscular administration

The efficacy of the lytic cocktail (1 ml contains pethidine 28 mg, promethazine 7 mg, chlorpromazine 7 mg) administered intramuscularly or rectally as premedication was studied in 51 children aged 1-12 years who had minor elective otological surgery. One group received 0.05 ml/kg intramuscularly (maximum dose 2.0 ml) and the other 0.07 ml/kg per rectum (maximum dose 2.8 ml). Most were satisfactorily sedated before operation, but after operation the rectally premedicated children were less sedated, which was in agreement with lower plasma pethidine concentrations in this group. The rectal dose should be increased if prolonged postoperative sedation is desireable.     

Effectiveness of preoperative sedation with rectal midazolam, ketamine, or their combination in young children.

To determine which of three types of rectal sedation was most effective preoperatively in facilitating parental separation and intravenous cannulation in young children, 100 children 3.0 +/- 1.7 (mean +/- SD) yr of age were randomly assigned to four equal groups. One group (M-K-A) received rectal midazolam (0.5 mg/kg), ketamine (3 mg/kg), and atropine (0.02 mg/kg). The other sedation groups received the same doses of midazolam and atropine (M-A) or ketamine and atropine (K-A) alone, and the control group (A) received only rectal atropine. Most children in either the M-K-A (100%) or M-A (92%) groups separated easily from their parents without struggling or crying, significantly more than in the K-A (60%) or A (64%) groups. However, more children in the M-K-A group (44%) were asleep during separation than in the M-A group (8%; P < 0.05). Only 20% of the children in the M-A or M-K-A groups cried during intravenous catheter placement, significantly less than in the K-A (56%) or A (92%) groups. Intravenous catheter placement was also successful significantly more often in the M-A (80%) and M-K-A (84%) groups than in the K-A (48%) or A (40%) groups. Complications were similar among the groups, but there was evidence that midazolam prolonged recovery time in some patients. Rectal midazolam with or without ketamine is a useful technique when intravenous catheter placement before induction of anesthesia is desired.     

Ketamine and midazolam is an inappropriate preinduction combination in uncooperative children undergoing brief ambulatory procedures

BACKGROUND: We prospectively studied the effects of intramuscular (i.m.) ketamine alone, or combined with midazolam, on mask acceptance and recovery in young children who were uncooperative during induction of anaesthesia. METHODS: The Institutional Review Board (IRB) approval was obtained to study 80 children, 1-3 years, scheduled for bilateral myringotomies and tube insertion (BMT). Mask induction was attempted in all the children. Those who were uncooperative were randomly assigned to one of the four preinduction treatment groups: group I, ketamine 2 mg.kg(-1); group II, ketamine 2 mg.kg(-1) combined with midazolam 0.1 mg.kg(-1); group III, ketamine 2 mg.kg(-1) with midazolam 0.2 mg.kg(-1); or group IV, ketamine 1 mg.kg(-1) with midazolam 0.2 mg.kg(-1). Anaesthesia was continued with nitrous oxide and halothane by facemask. RESULTS: Children in all treatment groups achieved satisfactory sedation in less than 3 min following the administration of the preinduction drug(s). Compared with patients who received halothane induction (comparison group), the use of ketamine alone did not significantly (P > 0.0167, a Bonferroni corrected significance level) delay recovery and discharge times (18.8 +/- 2.5 and 82.5 +/- 30.7 min vs 12.6 +/- 4.6 and 81.0 +/- 33.8 min, P = 0.030 and P = 0.941, respectively). Patients who received ketamine/midazolam combinations, however, had significantly longer recovery and discharge times vs halothane (32.3 +/- 14.0 and 128.0 +/- 36.6 min, P = 0.001, P = 0.007, respectively). These times were so clinically unacceptable, that the study had to be terminated with only 17 patients receiving study drugs. CONCLUSIONS: It is concluded that ketamine/midazolam combination is not appropriate for preinduction of anaesthesia in paediatric ambulatory patients because of unacceptably prolonged recovery and delayed discharge times.     

Rectal administration of morphine in children

Background : There is limited knowledge about the pharmacokinetics of morphine and its metabolites after rectal administration in children. In this study the pharmacokinetics of two different rectal formulations of morphine were examined and compared with intravenous morphine.
Methods : Children undergoing elective surgery received rectal morphine 0.2 mg/kg before start of surgery. Ten children (mean age 14 months) received morphine rectally in a hydro-gel formulation and another 10 children (mean age 16 months) received morphine rectally in a parenteral formulation. For comparison, 6 children (mean age 21 months) were given the same dose intravenously. The plasma concentrations of morphine, morphine-3-glucuronide (M3G) and mor-phine-6-glucuronide (M6G) were measured by HPLC over 6 h after drug administration.
Results : The mean rectal bioavailability of morphine was 35% (range 18–59) after hydrogel administration and 27% (range 6–93) after the solution. Mean values of Cmax were 76 nmol/1 (25–129) and 56 nmol/1 (15–140), respectively. The results showed that morphine gel had a significantly higher bioavailability (P<0.02) than the solution. The ratios of plasma (M3G + M6G) to morphine were higher after rectal administration (mean 7.5–8.7) than after i.v. injection (mean 5.3), indicating the presence of first-pass metabolism using the rectal route.
Conclusions : The rectal morphine hydrogel has pharmacokinetic properties which makes it a useful formulation for premedication and pain alleviation in paediatric patients.     

Pre-hospital use of ketamine in paediatric trauma

Objectives: To describe the use of ketamine in children by a pre-hospital physician-based service.
Methods: A five and a half year retrospective database review of all patients aged <16 years who were attended by London's Helicopter Emergency Medical Service and given ketamine.
Results: One hundred and sixty-four children met the inclusion criteria. The median age was 10 years (range 0–15 years). One hundred and four (63%) had a Glasgow Coma Scale (GCS) of 15 and 153 (93%) had a GCS>8 before administration of ketamine. Patients received from 2 to 150 mg ketamine IV (mean=1.0 mg/kg) and 112 (68%) received concomitant midazolam (0.5–18 mg, mean=0.1 mg/kg). One hundred and forty-one (86%) received ketamine intravenously and 23 (14%) intramuscularly. Only 12 patients (7%) were trapped. The most common mechanisms of injury in those who received ketamine were road traffic collisions, burns and falls.
Conclusion: The safe delivery of adequate analgesia and appropriate sedation is a priority in paediatric pre-hospital care. Ketamine was predominantly used in awake non-trapped patients with blunt trauma for procedural sedation and analgesia. Detailed database searches did not demonstrate loss of airway, oxygen desaturation or clinically significant emergence reactions after ketamine administration. This study failed to demonstrate any major side effects of the drug and reassured us that the safety profile of the drug in this environment is likely to be satisfactory. The use of ketamine in trapped children was rare.     

Nalbuphine and piritramid in the postoperative phase in young children. 1. General condition

The influence of piritramide and nalbuphine versus placebo on the postoperative comfort of 54 children of ASA-group I and II in the age between 1 and 4 years was tested in a randomized double blind trial using the comfort/discomfort scale according to Büttner et al. METHODS. Operations, premedication and anesthesia were standardized. The patients were premedicated with midazolam 0.5 mg/kg rectally and a subsequent i.m. injection of ketamine 2.0 mg/kg with atropine 0.01 mg/kg. Anesthesia was induced and maintained by inhalation of oxygen/nitrous oxide and halothane (FiO2 = 0.3). All children were intubated and ventilation was controlled during the operation. After the operation, while in steady-state anesthesia with 0.5 vol% halothane and during spontaneous respiration the children received either piritramide (n = 17) or nalbuphine (n = 20) at a dose of 0.1 mg/kg, or placebo (n = 17) i.v. Respiratory and circulatory parameters were recorded for 15 min before the end of anesthesia. At 5 min after halothane had been discontinued the first measurement of the children's behavior was started, with 4 subsequent measurements at fixed time intervals of 15 min. The measuring system included the following 6 scaled items: wake-up reaction, methodical defense against stimuli, crying, facial expression, posture of the torso, posture of the legs. In addition, the waking state was scored at the same time intervals as awake, arousable, or not arousable. During the 1-h observation period all children who seemed to feel uncomfortable received midazolam i.v. at a maximal dose of 2 mg. Up to 24 h the required supplemental analgesics were noted, as were episodes of psychomotor agitation and vomiting. Written consent was obtained from the ethical committee and the children's parents. The results were tested in a 2-factorial analysis of variance (treatment factor: drugs; within-subject factor; repeated measurements). RESULTS. The 3 groups were considered to be comparable in terms of age, body weight, kind and duration of operation and circulatory values. The use of supplementary analgesics showed a significant effect in the treatment factor and in the within-subject factor: during the 1-h observation period the placebo group received midazolam significantly more often (64.7%) than the piritramide group (5.9%) or the nalbuphine group (35%). During the following 7 h 29.4% of the children of the placebo group required supplementary analgesics (piritramide: 23.5%; nalbuphine: 20%). Subsequently up to the 24th postoperative hour there was no need for any analgesic in the placebo group, whereas 11.8% of the piritramide group and 15% of the nalbuphine group required analgesics.(ABSTRACT TRUNCATED AT 400 WORDS)     

Dexmedetomidine Premedication Attenuates Ketamine-induced Cardiostimulatory Effects and Postanesthetic Delirium

Background: Dexmedetomidine is a new potent and highly selective alpha2 -adrenoceptor agonist with sedative-hypnotic and anesthetic sparing properties. Because of its sympathoinhibitory activity, it may prove useful in balancing the cardiostimulalory effects and attenuating the adverse central nervous system effects of ketamine.

Methods: A double-blind, randomized and comparative parallel-group study design was employed in 40 volunteers with ASA physical status 1 who were scheduled for elective superficial surgery under ketamine anesthesia. Dexmedetomidine (2.5 micro gram/kg, n = 20) or midazolam (0.07 mg/kg, n = 20) was administered intramuscularly 45 min before induction of anesthesia. Anesthesia was induced with 2 mg/kg ketamine intravenously, and muscle relaxation was achieved with vecuronium. After tracheal intubation, anesthesia was maintained with nitrous oxide/oxygen (2:1) and additional 1 mg/kg intravenous ketamine boluses according t clinical and cardiovascular criteria. Hypotension and bradycardia were treated by increasing the intravenous infusion rate of crystalloids and intravenous atropine, respectively. Sedative and anxiolytic properties, intra- and postoperative drug requirements, psychomotor and cognitive impairments, and cardiovascular effects were compared between the two groups.

Results: Dexmedetomidine and midazolam proved to have equal sedative and anxiolytic effects after intramuscular administration, but dexmedetomidine induced significantly less preoperative psychomotor impairment and less anterograde amnesia than did midazolam. Compared to midazolam, dexmedetomidine decreased the need for intraoperative ketamine and was more effective in reducing ketamine-induced adverse central nervous system effects. Dexmedetomidine also was superior to midazolam in attenuating the hemodynamic responses to intubation and the cardiostimulatory effects of ketamine in general, but it increased the incidence of intra and postoperative bradycardia.     

Oral midazolam in children: effect of time and adjunctive therapy.

The purpose of this study was to determine the influence of timing and concomitant administration of atropine and/or meperidine on the perioperative effects of oral midazolam in children. In 154 healthy children, 1-8 yr old, we studied six oral preanesthetic medication regimens according to a randomized, double-blind protocol. Group A (placebo) received 5 mL of apple juice. The other five groups received medication with apple juice to a total volume of 5 mL, 20-60 min before induction of anesthesia. Group B received atropine (0.02 mg/kg); group C received midazolam (0.5 mg/kg); group D received midazolam (0.5 mg/kg) and atropine (0.02 mg/kg); group E received meperidine (1.5 mg/kg) and atropine (0.02 mg/kg); and group F received meperidine (1.5 mg/kg), atropine (0.02 mg/kg), and midazolam (0.5 mg/kg). The sedative effect of midazolam was maximal 30 min after oral administration. Ninety-five percent of the children who were separated from their parents within 45 min after oral midazolam administration (with or without atropine) had satisfactory separation scores (vs 66% of those separated after 45 min; P less than 0.02). Midazolam-treated patients were more cooperative with a mask induction of anesthesia compared with non-midazolam-treated children (83% vs 56%). Neither atropine nor meperidine appeared to significantly improve the effectiveness of oral midazolam. No preoperative changes in heart rate, respiratory rate, or hemoglobin oxygen saturation were noted in any of the treatment groups. Finally, oral midazolam did not prolong recovery even after outpatient procedures lasting less than 30 min. In conclusion, midazolam (0.5 mg/kg) given orally 30-45 min before induction of anesthesia is safe and effective without delaying recovery after ambulatory surgery.     

Rectal premedication with midazolam in children. A comparative clinical study

Anesthetic premedication by injection is usually poorly accepted by children, especially those under 10 years of age. Less disturbing for the child is oral premedication, but this increases the risk of aspiration and must be administered 1.5-2 h before anesthetic induction. This double-blind study was performed in children to investigate the efficacy, acceptance, and general safety of midazolam given rectally. METHOD. Rectal premedication was administered to a total of 80 healthy children between 2 and 10 years of age undergoing elective operations. The children were divided randomly into two groups: group I received 0.4 mg/kg and group II 0.5 mg/kg midazolam with the addition of 0.015-0.02 mg/kg atropine. Premedication was carried out on the pediatric ward. The calculated dose was drawn from the ampule and diluted to 8-10 ml with distilled water. This dose was instilled immediately behind the anal sphincter using a suitable plastic applicator (Stanylan). The following parameters were recorded: immediate reaction to the rectal medication, sedative-hypnotic signs, and acceptance of the anesthetic mask. Heart rate and blood pressure were measured before premedication and before the induction of anesthesia. Observations were made for 5 h post-operatively. Any unusual side effects of the treatment were also noted. The existence of any anterograde amnesia was investigated in 20 children (10 in each group) between 6 and 10 years of age. RESULTS. There was no significant difference between the children allocated to the two groups with regard to age, body weight, sex, type of operation, and duration of anesthesia (Table 2). Of the total of 80 children, 66 (82.5%) accepted the rectal instillation well, 12 (15%) moderately well, and 2 (2.5%) poorly. Signs of respiratory depression or allergic reaction to midazolam were not observed in any case. The observations made before induction of anesthesia are presented in Table 3. The children in group II exhibited significantly greater (P less than 0.05) slurred speech than those in group I. A low incidence of hiccup was seen in both groups. Most of the children (27 in group I, 67.5%; 37 in group II, 92.5%: P less than 0.05) were delivered to the operating room lying down, whereas the others were sitting up in bed but showed no desire to get up. Between 10 and 55 min after the premedication, a total of 5 children (12.5%) in group I and 2 (5%) in group II were restless or crying on arrival in the induction room. Most, however, were quiet to tired/drowsy. The optimal sedative-hypnotic action was observed after 20-30 min (Fig. 1). At this time 21.7% of the children in group I were tired/drowsy, whereas 50% in group II were tired/drowsy and 9.1% were asleep but easy to arouse. This effect was significantly greater in group II (P less than 0.01). Acceptance of the mask was comparable in both groups (Table 4) and was tolerated well to very well by 92-97% of the children. (ABSTRACT TRUNCATED AT 400 WORDS)     

A comparison of two different doses of ketamine with midazolam and midazolam alone as oral preanaesthetic medication on recovery after sevoflurane anaesthesia in children

BACKGROUND: This investigation prospectively evaluated the effect of oral premedication of two different doses of ketamine with midazolam and midazolam alone on the recovery of children after sevoflurane anaesthesia. METHODS: In a randomized, double-blind study, 79 children (aged 1-8 years, ASA physical status I or II) were assigned to receive one of three premedications in a volume of 0.5 ml x kg(-1): group 1 received midazolam 0.5 mg x kg(-1) (MD); group 2 received midazolam 0.5 mg x kg(-1) with ketamine 1.8 mg x kg(-1) (MK-1); and group 3 received midazolam 0.5 mg x kg(-1) with ketamine 3 mg x kg(-1) (MK-2). The reactions of the children during administration were noted. Anaesthesia was induced by facemask with incremental sevoflurane administration. All children received alfentanil (15 micro g x kg(-1)). Tracheal intubation was facilitated by mivacurium (0.2 mg x kg(-1)). Anaesthesia was maintained with sevoflurane and an additional dose of alfentanil, if necessary. During recovery, the time interval between discontinuation of anaesthesia and arousal (spontaneous ventilation, extubation) were recorded. RESULTS: Emergence (spontaneous ventilation, extubation) and recovery times (discharge, Aldrete score=9) did not differ significantly between groups (P=0.24, P=0.59 and P=0.145, respectively). CONCLUSIONS: The combination of midazolam and ketamine as oral preanaesthetic medication did not significantly affect the recovery time of children after sevoflurane anaesthesia.