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.     

Comparison of oral transmucosal fentanyl citrate and an oral solution of meperidine, diazepam, and atropine for premedication in children

The safety and efficacy of premedication with oral transmucosal fentanyl citrate (OTFC) was compared with that of an orally administered solution of meperidine, diazepam, and atropine and no premedication in 59 children about to undergo elective operations. The patients were randomly assigned to receive no premedication (n = 19); 0.25 ml/kg of the oral solution (containing meperidine, 1.5 mg/kg, diazepam, 0.2 mg/kg, and atropine, 0.02 mg/kg, n = 20); or OTFC (15-20 micrograms/kg, n = 20). Children had activity (sedation) and anxiety scores, vital signs (including systolic and diastolic arterial blood pressures and heart and respiratory rates) and pulse oximetry determined oxygen saturation measured before and at 10-min intervals after premedication until they were taken to the operating room. Quality of induction and recovery was evaluated using scoring schedules; recovery times were measured and side effects noted. OTFC was readily accepted and provided significant reductions in preoperative activity (sedation) and anxiety starting after 30 min. After OTFC, sedation and anxiolysis were significantly greater than in children having no premedication but similar to children having the oral solution for premedication. Vital signs and oxygen saturations remained unchanged preoperatively in all groups. Induction and recovery evaluations and recovery times were similar in the three groups, although children having OTFC had the lowest requirements for narcotics in the recovery room. OTFC caused an 80% incidence of mild preoperative facial pruritus and a higher overall incidence of postoperative vomiting (37%) than premedication with the oral solution (5%) or no premedication (18%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Postoperative agitation in preschool children following emergence from sevoflurane or halothane anesthesia: A randomized study on the forestalling effect of midazolam premedication versus parental presence at induction of anesthesia

ObjectiveThe effect of midazolam premedication on forestalling postoperative agitation in children is not yet concluded. The purpose of this study was to compare the effects of midazolam premedication and parental presence during anesthetic induction on the incidence of postoperative agitation in pediatric patients.MethodsOne hundred sixty-seven children between 2 years and 7 years of age, undergoing anesthesia for outpatient surgery, were enrolled and randomly divided into four groups: sevoflurane anesthesia with parental presence without premedication, sevoflurane anesthesia with oral midazolam premedication, halothane anesthesia with parental presence without premeditation, and halothane anesthesia with oral midazolam premedication. The children randomized to the premedication groups took oral midazolam 0.5 mg/kg 20–30 minutes before anesthetic induction. For patients in the groups without premedication, one of the parents was present throughout the induction of anesthesia. One recovery room nurse blinded to the group assignment observed the patients and recorded the agitation scores all through their stay in the postanesthesia care unit.ResultsPostoperative agitation was significantly less in patients who received halothane anesthesia with oral midazolam premedication (p < 0.002).ConclusionBased on our data, the presence of a parent at induction of sevoflurance anesthesia was as effective as midazolam premedication in decreasing the incidence of postoperative agitation. Midazolam premedication, however, decreased postoperative agitation when halothane was used as the anesthetic agent.     

Rectal methohexital: concentration and length of the rectal catheters

In the study, the authors evaluated the concentration of rectal methohexital (1% vs 10%) and the length of the rectal catheter (3.8 vs 12.7 cm), on sleep-success rate, administration-sleep time, methohexital plasma concentrations, and recovery time in 85 healthy children scheduled for elective ophthalmic or ear, nose, or throat operations lasting approximately 1 h. At a dose of 25 mg/kg, the 1% solution of rectal methohexital was associated with a significant (P less than 0.05) higher sleep-success rate (95% vs 70%), shorter administration-sleep time (5.7 +/- 1.9 vs 7.0 +/- 2.0 min), higher methohexital plasma concentrations at 20 min (6.5 vs 4.7 ng/mL) and at 30 min (5.3 vs 3.7 ng/mL), and prolonged recovery time (53.2 +/- 31.1 vs 32.4 +/- 18.5 min). The length of the rectal catheters did not significantly affect sleep-success rate, administration-sleep time, methohexital plasma concentrations, or recovery time. The use of 25 mg/kg of 1% rectal methohexital solution to induce anesthesia in children is superior to the use of 25 mg/kg of 10% methohexital solution for induction of anesthesia in children, particularly in operations 1 h or longer in duration.     

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.     

Premedication with midazolam delays recovery after ambulatory sevoflurane anesthesia in children.

We studied the effect of oral premedication with midazolam on the recovery characteristics of sevoflurane anesthesia in small children. In a randomized, double-blinded study, 60 children (1-3 yr, ASA physical status I or II) undergoing ambulatory adenoidectomy received either midazolam 0.5 mg/kg (Group M) or placebo (Group P) PO approximately 30 min before the induction of anesthesia. All children received atropine 0.01 mg/kg IV and alfentanil 10 microg/kg IV before the induction of anesthesia with sevoflurane up to 8 vol% inspired concentration in N2O 67% in O2. Tracheal intubation was facilitated with mivacurium 0.2 mg/kg. Anesthesia was continued with sevoflurane adjusted to maintain hemodynamic stability. In the postanesthesia care unit, predetermined recovery end points (emergence, recovery, discharge) were recorded. A pain/ discomfort scale was used to determine the quality of recovery. A postoperative questionnaire was used to evaluate the well-being of the patient at home 24 h after surgery. Emergence (spontaneous eye opening), recovery (full points on the modified Aldrete scale), and discharge were achieved later in Group M than in Group P (15+/-6 vs. 11+/-3 min [P = 0.002], 25+/-17 vs. 16+/-6 min [P = 0.01], and 80+/-23 vs. 70+/-23 min [P = 0.03]). Side effects, postanesthetic excitement, and analgesic treatment did not differ significantly between groups. At home, more children in Group P (30%) experienced disturbed sleep during the night compared with those in Group M (4%) (P = 0.007). IMPLICATIONS: In this randomized, double-blinded, placebo-controlled study, premedication with midazolam 0.5 mg/kg PO delayed recovery in children 1-3 yr of age after brief (<30 min) sevoflurane anesthesia. Except for more peaceful sleep at home, premedication did not affect the quality of recovery.     

Cardiovascular effects of rectal methohexital in children.

STUDY OBJECTIVE: To define the cardiovascular effects of rectal methohexital in children with normal cardiac function. DESIGN: Cardiovascular evaluation of each patient was performed before and after medication. Each patient's predrug results were used as control measurements for comparison with measurements made after methohexital administration. SETTING: Inpatient operating room induction area in a privately endowed philanthropic children's hospital. PATIENTS: Forty-seven children age 35 +/- 22 months (mean +/- SD) scheduled for elective orthopedic or plastic surgery, free of cardiac or pulmonary disease, and receiving no medication with central nervous system activity. INTERVENTIONS: Control measurements of heart rate (HR), blood pressure (BP), and echocardiographic evaluations were obtained on the day before scheduled surgery. Repeat measurements were performed after the onset of methohexital-induced sleep. The time span of the measurements was designed to include the period of peak plasma methohexital concentration. In the preoperative holding area, 30 mg/kg of a 10% methohexital solution was administered rectally. If sleep did not occur in 15 minutes, an additional 15 mg/kg was given. MEASUREMENTS AND MAIN RESULTS: HR increased markedly after rectal methohexital [126 +/- 23 beats per minute (bpm) to 144 +/- 21 bpm, p less than 0.001], and stroke volume (SV) decreased (24 +/- 9 ml to 21 +/- 8 ml, p less than 0.01). There were no significant changes in BP or cardiac index. The shortening fraction and ejection fraction remained within the normal range for this age-group. CONCLUSIONS: Rectal methohexital induces sleep in healthy pediatric patients with minimal cardiovascular side effects. The primary effects are increased HR and decreased SV.     

Children's drawings as a measure of anxiety level: a clinical pilot study

BACKGROUND: No simple method exists to distinguish children in need for premedication. The present study was planned to detect preoperative anxiety levels of children by rating their drawings. METHODS: Sixty ASA I children aged 4-7 years undergoing adenoidectomy were divided into AGIT and CALM groups according to agitation level observed during venous cannulation. All children drew a picture at three different times: (i) just after arrival in the day-case unit, (ii) 10 min before operation and, (iii) prior to leaving for home. The children were also randomized to three premedication groups: group D, rectal diazepam 0.5 mg x kg(-1); group P, 0.9% NaCl 0.1 ml x kg(-1) rectally; group NT, no premedication. Five features (size of the drawing, form of the drawing line, colors used, mark of the pen and clarity of the picture) from the children's drawings were rated with a 3-point scale. The ratings of each feature were made to form a sum score of anxiety ranging from 0 to 10. In the analysis of variance for repeated measures both the premedication group and agitation score were taken into the model as factors. RESULTS: The anxiety score of the drawings of the agitated children (during venous cannulation) was significantly higher already after arrival in the hospital [AGIT 4.76 (95% CI: 3.56-5.96) Vs CALM 3.67 (95% CI: 2.97-4.37) P = 0.029], but there were no statistical differences between the different premedication groups. CONCLUSIONS: When routine sedative premedication is not used the drawings of the children might detect the children needing sedative premedication.     

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.     

Oral ketamine premedication can prevent emergence agitation in children after desflurane anaesthesia

BACKGROUND: The purpose of the present study was to determine whether oral ketamine premedication affected the incidence of emergence agitation in children. METHODS: Thirty minutes before induction of anaesthesia, 80 children who were undergoing adenotonsillectomy with or without bilateral myringotomy and insertion of tubes received either ketamine 6 mg.kg(-1) per oral in group K or sour cherry juice alone in group C. Anaesthesia was maintained with desflurane. Emergence and recovery times were recorded. Tramadol was used for postoperative analgesia. Fentanyl (1 microg.kg(-1)) was administered for the treatment of emergence agitation or severe pain that still continued after tramadol administration. Postoperative behaviour was evaluated using a 5-point agitation scale. RESULTS: The incidence of emergence agitation was 56% in group C, and 18% in group K (P = 0.001). There was no significant difference with respect to emergence times except from time to eye opening that was significantly longer in group K (P < 0.0001). CONCLUSION: Oral ketamine premedication reduced the incidence of postanaesthesia emergence agitation in children without delaying recovery.     

Midazolam premedication delays recovery from propofol-induced sevoflurane anesthesia in children 1–3 yr

PURPOSE: To study the effect of midazolam premedication on the recovery characteristics of sevoflurane anesthesia induced with propofol in pediatric outpatients. METHODS: Sixty children, one to three years, presenting for ambulatory adenoidectomy were randomly assigned , in a double-blind fashion, to receive either 0.5 mg x kg(-1) midazolam (Group M) or placebo (Group P) p.o. 30 min before anesthesia. Anesthesia was induced with 10 microg x kg(-1) atropine, 10 microg x kg(-1) alfentanil, and 3-4 mg x kg(-1) propofol i.v.. Tracheal intubation was facilitated with 0.2 mg x kg(-1) mivacurium. Anesthesia was maintained with nitrous oxide/oxygen (FiO2 0.3) and sevoflurane with controlled ventilation. Recovery characteristics were compared using the modified Aldrete scoring system, the Pain/Discomfort scale and measuring specific recovery end-points (emergence, full Aldrete score, discharge). A postoperative questionnaire was used to evaluate the children's well-being at home until 24 hr after discharge. RESULTS: Emergence from anesthesia (22 +/- 9 vs 16 +/- 6 min (mean +/- SD), P = 0.005) and achieving full Aldrete scores (30 +/- 11 vs 24 +/- 16 min, P = 0.006) were delayed in patients receiving midazolam. Children in the placebo group were given postoperative analgesia sooner than those in the midazolam group (18 +/- 11 vs 23 +/- 8 min, P = 0.009). More children premedicated with midazolam suffered from arousal distress (20% vs 3%, P = 0.04) and scored higher on the Pain/Discomfort scale (P = 0.004) at 20 min after arrival in the recovery room. Discharge was not affected by premedication and well-being at home was similar in the groups. CONCLUSIONS: Oral premedication with midazolam delays early recovery but not discharge after ambulatory sevoflurane anesthesia induced with propofol in children one to three years. Midazolam did not improve the quality of recovery.     

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.     

The comparative dose-response effects of melatonin and midazolam for premedication of adult patients: a double-blinded, placebo-controlled study

We designed this prospective, randomized, double-blinded, placebo-controlled study to compare the perioperative effects of different doses of melatonin and midazolam. Doses of 0.05, 0.1, or 0. 2 mg/kg sublingual midazolam or melatonin or placebo were given to 84 women, approximately 100 min before a standard anesthetic. Sedation, anxiety, and orientation were quantified before, 10, 30, 60, and 90 min after premedication, and 15, 30, 60, and 90 min after admission to the recovery room. Psychomotor performance of the patient was evaluated at these times also, by using the digit-symbol substitution test and Trieger dot test. Patients who received premedication with either midazolam or melatonin had a significant decrease in anxiety levels and increase in levels of sedation preoperatively compared with control subjects. Patients in the three midazolam groups experienced significant psychomotor impairment in the preoperative period compared with melatonin or placebo. After operation, patients who received 0.2 mg/kg midazolam premedication had increased levels of sedation at 90 min compared with 0.05 and 0. 1 mg/kg melatonin groups. In addition, patients in the three midazolam groups had impairment of performance on the digit-symbol substitution test at all times compared with the 0.05 mg/kg melatonin group. Premedication with 0.05 mg/kg melatonin was associated with preoperative anxiolysis and sedation without impairment of cognitive and psychomotor skills or affecting the quality of recovery. Implications: Premedication with 0.05 mg/kg melatonin was associated with preoperative anxiolysis and sedation without impairment of cognitive and psychomotor skills or affecting the quality of recovery.     

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)     

Patients' Expectations and Acceptance of the Effects of the Drugs Given Before Anaesthesia: Comparison of Light and Amnesic Premedication

Patients (130) scheduled for elective general surgery under balanced general anaesthesia were interviewed on the day before operation and asked whether they wanted a light premedication allowing them to remember all events before and after surgery or whether they wanted a potent premedication rendering them amnesic for the events before and after operation. Regardless of their preferences, the patients were given 1 mg/kgofpethidine; 12.5 to 50 mg of promethazine, plus 0.14 mg/kg oxycodone; or 0.05 mg/kg of lorazepam; and 0.01 mg/kg of atropine intramuscularly in random fashion as preanaesthetic medication before operation. On the first postoperative day, patients were questioned again about their opinions of the premedication. Most patients wanted light (53%) or moderate (22%) premedication, and only 5% wanted to receive amnesic premedication. Assessments of degree of fatigue and apprehension were similar after each premedication when assessed before operation. Sixty-seven and 60% of the patients receiving lorazepam did not remember insertion of the i.v. needle before induction of anaesthesia or the stay in the recovery room, respectively (P<0.01 vs. other groups), whereas most of the patients given pethidine or oxycodone recalled the events before and after operation. Almost all the patients who both expected and received a light (91% acceptance) or an amnesic (100% acceptance) premedication accepted it. However, only 58% of patients who expected to be given a light but received an amnesic premedication were satisfied with it, whereas 89% of patients who expected an amnesic but received a light premedication accepted it. It is concluded that patients' opinions on the potency and capacity of preanaesthetic medication to produce amnesic action should be taken into account in routine clinical work. Administration of a potent, amnesic premedication is indicated only if patients prefer it to light premedication.     

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)     

Ondansetron does not modify emergence agitation in children

In this prospective, placebo-controlled study, we evaluated the effect of prophylactic ondansetron therapy on emergence agitation of children who underwent minor surgery below the umbilicus. Seventy children aged one to six years and American Society of Anesthesiologists physical status I were studied. Children were premedicated with midazolam rectally and were randomly assigned to receive either ondansetron (Group O) or placebo (Group P) in combination with caudal anaesthesia. Children in Group O received intravenous ondansetron (0.1 mg/kg for children weighing < 40 kg, 4 mg for children weighing > 40 kg) and Group P (n = 35) received normal saline 2 ml following anaesthesia induction with sevoflurane. Airway management was provided with LMA-Proseal without muscle relaxation and anaesthesia maintenance was provided with a 60:40 N2O:O2 mixture and sevoflurane. Emergence agitation was evaluated with a ten point scale and pain level was assessed every 10 minutes for the first 30 minutes after admission to the recovery room. There were no significant differences between the placebo and ondansetron groups with respect to demographic, anaesthetic and surgical details. Incidences of emergence agitation in ondansetron and placebo groups were similar (32.4% and 30.3% at 10 minutes respectively). Mean modified Children's Hospital of Eastern Ontario pain scale scores and mean ten-point scale scores and emergence agitation incidences decreased similarly after 10 minutes in both groups. Ready time for discharge was similar between the groups. Agitated patients had significantly increased ready time for discharge compared to non-agitated patients (P = 0.001). Prophylactic intravenous ondansetron administration does not reduce emergence agitation comparing to placebo after sevoflurane anaesthesia.     

Effects of sevoflurane anaesthesia on recovery in children: a comparison with halothane

We prospectively studied one hundred ASA physical status I-II children, ages six months to six years, undergoing myringotomy surgery. Children were randomly assigned to one of four anaesthetic groups receiving either halothane or sevoflurane for anaesthesia and oral midazolam premedication or no premedication. We found that children anaesthetized with sevoflurane had significantly faster recovery times and discharge home times than those who received halothane. Patients given oral midazolam premedication had significantly longer recovery times, but no delay in discharge home compared with those not premedicated. However, children anaesthetized with sevoflurane and no premedication had an unacceptably high incidence (67%) of postoperative agitation. The use of oral midazolam preoperatively did decrease the amount of postoperative agitation seen with sevoflurane. We conclude that although sevoflurane does shorten recovery times, the degree of associated postoperative agitation makes it unacceptable as a sole anaesthetic for myringotomy surgery.     

EFFECTS OF THE RECTAL ADMINISTRATION OF DIAZEPAM: Diazepam Concentrations in Children Undergoing General Anaesthesia

Diazepam 1 mg/kg body weight was administered rectally to 14children (11–22.5 kg) before minor surgery under generalanaesthesia. Administration in solution (n = 7) resulted ina rapid increase in serum concentrations which were maintainedfor 8 h. Administration by suppository (n = 7) resulted in significantlylower serum concentrations at 10 and 20 min, but higher concentrationsat 2 h. At other intervals the concentrations did not differfrom those reached after administration of diazepam in rectalsolution. These results favour the use of a solution when rectaldiazepam is used for premedication in children.     

Methohexital plasma concentrations in children following rectal administration

Despite the increasing use of rectal methohexital as a premedicant-induction agent in pediatric anesthesia, there are no data to confirm the assumption that low plasma methohexital concentrations are the cause of inadequate sedation of children and that high concentrations are associated with the loss of consciousness. Plasma methohexital concentrations were determined in 20 ASA Class I children, ages 2-7 yr, after the rectal administration of methohexital (25 mg/kg). Seventeen of the 20 children in this study fell asleep after receiving the drug and achieved peak plasma concentrations greater than 2 micrograms/ml. The maximum plasma methohexital concentration in children that did not fall asleep was less than 2 micrograms/ml. The mean time to the onset of sleep after drug administration was 8.3 min (at which time the mean plasma concentration was 4.4 micrograms/ml). The mean peak plasma concentration and the mean time to peak plasma concentration were 4.7 micrograms/ml and 13.9 min, respectively. Loss of consciousness after rectal administration of methohexital correlates well with the plasma concentration of the drug.