Arterial oxygen saturation in children receiving rectal midazolam as premedication for oral surgical procedures

Eighty healthy children, between the ages of 2 and 7 years, undergoing dental procedures were monitored with a pulse oximeter for changes in arterial oxygen saturation. The children were randomly allocated into 4 groups in this double-blind study. Three groups received rectal midazolam, and the other group a placebo (saline) as premedication 30 min prior to induction of anesthesia. Group A children received midazolam 0.25 mg/kg, Group B 0.35 mg/kg and Group C 0.45 mg/kg. The results from this trial show no statistical significant difference between the treatment groups as to the effect on either systolic or diastolic blood pressure, respiration, or pulse rates at either pre- or post-sedation levels. However, the oxygen saturation levels for groups B and C differed significantly from those of the placebo groups 30 minutes after premedication (P = 0.0259).     

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.     

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.     

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)     

The pharmacokinetics of midazolam following intramuscular administration

There have been conflicting reports on the pharmacokinetics of midazolam, administered i.m. The aims of this study were to determine the pharmacokinetic data of midazolam following different doses and to test whether a correlation exists between its plasma level and sedative effect. METHODS. Fifteen patients between the ages of 18 and 50 were divided into three groups for i.m. administration of midazolam 0.05 mg/kg (group 1), 0.1 mg/kg (group 2), or 0.15 mg/kg (group 3) i.m. Venous blood was drawn 6, 12, 18, 24, 30, 36, 42, 48, 54, 60 min, and 2, 3, 4, 6, 8 h after the injection. After the same times the sedative effect was estimated by the anesthetist (awake, sleeping but easy to wake, sleeping and difficult to wake, unconscious). The plasma midazolam levels were determined by gas chromatography. The following pharmacokinetic parameters were ascertained: Cmax (peak concentration), tmax (time to attain peak concentration), clearance, elimination half-life. RESULTS. The peak concentration is directly proportional to the dosage of midazolam and the relation between the two is linear. The median Cmax values were 35.3 ng/ml (group 1), 103 ng/ml (group 2) and 123.5 ng/ml (group 3). The duration of tmax was between 12 and 36 min (means = 27 min). There was no significant difference between the groups in clearance, tmax, or elimination half-life. A significant correlation was found between the plasma midazolam levels and the degree of sedation. However, we observed a considerable variability in the effect. CONCLUSION. A 95% confidence interval for the prediction of the peak concentration of midazolam after i.m. injection is stated. Midazolam should be administered at a dose of 0.05 mg/kg at the most, if unconsciousness after premedication is to be avoided.     

Significant CO2 retention in children after premedication with Dormicum and Thalamonal

Whereas in adults the use of Innovar for premedication has been abolished, the combination of midazolam and Innovar is still recommended for the premedication of children. This combination may lead to an additional depressive effect on respiration. A prospective, randomized study was performed to evaluate the risk of ventilatory depression. In 36 infants capillary blood gas values were measured pre- and postmedication with either rectal midazolam (0.4 mg/kg) and i.m. Innovar (0.04 ml/kg) or after oral chlorprothixene (2.0 mg/kg). After chlorprothixen the blood gas values did not change, whereas after the combination of midazolam and Innovar pCO2 rose significantly from 35.5 to 43.0 mmHg. In 7 of 22 cases pCO2 reached values above 45 mmHg. This difference compared to the chlorprothixene group was significant (p less than 0.05). The pH fell significantly from 7.42 to 7.36 in the combination group. Clinical signs of respiratory depression could not be observed in this group. The combination of midazolam with Innovar is therefore not useful for premedication in infants and young children.     

枸橼酸钠对先天性心脏病患儿咪达唑仑口服术前用药效果的影响

目的 探讨枸橼酸钠对先天性心脏病患儿咪达唑仑口服术前用药效果的影响.方法 选择拟行房缺修补术、室缺修补术或动脉导管结扎术的患儿40例,年龄2～6岁,体重12～20 kg,ASA分级Ⅱ或Ⅲ级,随机分为2组(n=20):对照组(C组)和枸橼酸钠组(S组).口服术前用药:S组为咪达唑仑0.12 ml/kg、氯胺酮0.12 ml/kg、葡萄糖0.12 ml/kg和枸橼酸钠0.12 ml/kg,等容积混合;C组为咪达唑仑0.12 ml/kg、氯胺酮0.12 ml/kg和葡萄糖0.24 ml/kg,等容积混合.用pH值1.75的盐酸模拟胃液,与两组配置好的药液在体外混合,分别测定两组混合药液的pH值.记录术前焦虑评分,口服术前药(0.48 ml/kg)后,记录咪达唑仑起效时间、镇静评分和与父母分离评分.入室后记录HR、MAP和SpO2,记录患儿对静脉穿刺反应评分和服药后的不良反应发生情况.结果 与盐酸混合后C组药物pH值为1.97,S组为4.52.两组患儿均成功口服术前药物.与C组比较,S组与父母分离评分、镇静评分和静脉穿刺反应评分降低,咪达唑仑起效时间缩短(P＜0.05),术前焦虑评分差异无统计学意义(P＞0.05);两组患儿入室时HR、MAP和SpO2均在正常范围.两组患儿在服药后均未出现恶心呕吐、呼吸抑制等不良反应.结论 作为先天性心脏病患儿口服术前用药时,枸橼酸钠可提高药液的pH值,缩短咪达唑仑起效时间,加强镇静效果.     

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.     

Midazolam premedication in children: a comparison of two oral dosage formulations on sedation score and plasma midazolam levels

We compared two available oral formulations of midazolam with respect to sedation score and plasma midazolam levels in pediatric surgical patients 2-10 yr old. The commercially available oral syrup was compared with a mixture of the IV midazolam preparation in Syrpalta syrup at an equivalent concentration of 2 mg/mL. ASA status I-II patients were randomly assigned to receive 0.5 mg/kg of either the commercial syrup (Group 1) or the prepared mixture (Group 2) as anesthetic premedication. Observer's Assessment of Alertness/Sedation scores were obtained by a blinded observer at 15 and 30 min after drug administration. Plasma midazolam levels were acquired exactly 45, 60, and 90 min after administration. Group 2 patients had a significantly lower median Observer's Assessment of Alertness/Sedation score (Group 1, 17; Group 2, 15) at 30 min (P < 0.03) and significantly higher mean plasma midazolam levels at all three acquisition times (mean +/- SD) (45 min: 63.1 +/- 23.9 ng/mL, Group 2; 43.4 +/- 19.6 ng/mL, Group 1; 60 min: 45.8 +/- 18.2 ng/mL, Group 2; 30.8 +/- 17.9 ng/mL, Group 1; 90 min: 28.9 +/- 12.6 ng/mL, Group 2; 21.0 +/- 8.9 ng/mL, Group 1) (P < 0.02). We conclude that IV midazolam mixed in Syrpalta syrup yields more reliable sedation and correspondingly higher plasma levels than an equivalent dose of the commercially formulated and marketed preparation.     

Premedication with nasal s-ketamine and midazolam provides good conditions for induction of anesthesia in preschool children

PURPOSE: To evaluate the efficacy and safety of intranasally administered s-ketamine and midazolam for premedication in pediatric patients. METHODS: Ninety children were randomly allocated to receive intranasally administered s-ketamine 1 mg.kg(-1) and midazolam 0.2 mg.kg(-1) (Group K1, n = 30), s-ketamine 2 mg.kg(-1) and midazolam 0.2 mg.kg(-1) (Group K2, n = 30), or midazolam 0.2 mg.kg(-1) (Group M, n = 30) as premedicants, using a double-blind study design. Sedation and anxiolysis were evaluated using a sedation and cooperation scale and recorded at several time points. RESULTS: Acceptable conditions (K1: 23; K2: 26, M: 19) for parental separation were not different between groups. Induction conditions were acceptable in 26 patients in K2 (P < 0.05 vs M) (K1: 23; M: 19). Compared to baseline values individual conditions significantly improved in groups K1 and K2 from 2.5 min after premedication until induction of anesthesia (P < 0.003), in group M conditions improved only five minutes after premedication (P < 0.05). Adverse effects observed in this series were within an acceptable range and similar for the three groups. CONCLUSION: Intranasal administration of s-ketamine and midazolam is an appropriate premedication in preschool children.     

Behavioural changes in children following minor surgery--is premedication beneficial?

One hundred and twenty-three male children, aged one to ten years, were studied to determine the influence of premedication on changes in patterns of behaviour following hospitalization for repair of inguinal hernias. Four comparable groups were selected for premedication regimen: (1) A control group without premedication; (2) oral trimeprazine tartrate 2 mg/kg, methadone 0.1 mg/kg and droperidol 0.15 mg/kg; (3) oral midazolam 0.45 mg/kg; (4) intramuscular midazolam 0.15 mg/kg. Standard inhalational anesthesia was used and caudal blocks employed for analgesia. The parents returned a questionnaire at two weeks. Changes in behaviour were reported in 78% of the children and overall, premedication showed little benefit. However, midazolam premedication was associated with a significantly lower incidence of night-time crying and awakening, compared with no premedication. Only for night-time crying and day-time toilet training did age below five years prove to be a significant contributing factor.     

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.     

PLASMA CONCENTRATIONS OF MIDAZOLAM AFTER I.V., NASAL OR RECTAL ADMINISTRATION IN CHILDREN

Midazolam is used frequently for premedication in children,preferably by non-parenteral administration. We have comparedplasma concentrations of midazolam after nasal, rectal and i.v.administration in 45 children (aged 2–9 yr; weight 10–30kg) undergoing minor urological surgery. General anaesthesiaconsisted of spontaneous respiration of halothane and nitrousoxide in oxygen via a face mask. After administration of atropineand fentanyl i.v., children were allocated randomly to receivemidazolam 0.2 mg kg^-1 by the nasal, rectal or i.v. route. Inthe nasal group, children received 50% of the dose of midazolamin each nostril. In the rectal group, midazolam was given rectallyvia a cannula. Venous blood samples were obtained before andup to 360 min after administration of the drug. Plasma concentrationsof midazolam were measured by gas chromatography and electroncapture detection. After nasal and rectal administration, midazolamCmax was 182 (SD 57) ng ml–1 within 12.6 (5.9) min, and48 (16) ng ml^-1 within 12.1 (6.4) min, respectively. Rectaladministration resulted in smaller plasma concentrations. Inthe nasal group, a plasma concentration of midazolam 100 ngml^-1 occurred at about 6 min. After 45 min, the concentrationcurves after i. v. and nasal midazolam were similar. (Br. J.Anaesth. 1993; 70:617–620)     

S-ketamine and s-norketamine plasma concentrations after nasal and i.v. administration in anesthetized children

BACKGROUND: It has been suggested that nasal administration of s-ketamine may be used to improve sedation or premedication in combination with nasal midazolam in pediatric patients. In this study we measured and compared plasma concentrations of s-ketamine and its main metabolite s-norketamine after nasal and i.v. administration in preschool children. METHODS: During sevoflurane anaesthesia, 20 children, aged 1-7 years, weight 11-25 kg, received s-ketamine 2 mg x kg(-1) either intranasally (Group IN, n = 10), or i.v. (Group IV, n = 10). Six venous blood samples were obtained up to 60 min after drug administration for measurement of s-ketamine and s-norketamine plasma concentrations. RESULTS: Plasma concentrations [mean +/- sd] of s-ketamine in group IN peaked at 355 +/- 172 ng x ml(-1) within 18 +/- 13 min vs. 1860 +/- 883 ng x ml(-1) within 3 +/- 1 min in group IV (P < 0.01). Plasma concentrations of s-norketamine in group IN peaked at 90 +/- 128 ng x ml(-1) within 50 +/- 11 min vs. 429 +/- 277 ng x ml(-1) within 40 +/- 16 min in group IV (P < 0.01). One child in group IN experienced rapid and high level s-ketamine absorption with a peak plasma concentration of 732 ng x ml(-1) after 2 min, which decreased to 274 ng x ml(-1) after 60 min. Systolic blood pressure and heart rate remained unaltered in both study groups after s-ketamine administration. CONCLUSIONS: Nasal administration of s-ketamine 2 mg x kg(-1) results in a wide spread of plasma concentrations and absorption times. Rapid and high level drug absorption after nasal drug administration is possible. The use of a pulse oximeter and continuous observation after nasal administration of s-ketamine for pediatric premedication is recommended.     

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.     

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.     

The Influence of Body Weight on Plasma Concentration of Atropine after Rectal Administration in Children

To avoid an unpleasant injection, the rectal administration of drugs to children is often to be preferred. Very little has been published on plasma concentrations of atropine given rectally. To determine whether body weight has any influence on the plasma concentrations of atropine, 18 children weighing 7.5-55.0 kg were given 0.02 mg atropine sulphate per kg rectally, and the plasma levels of atropine were determined. The mean peak plasma concentration of atropine was 1.17 ng/ml and it was reached after 33 min. In the group of smaller children (b.w. less than 15 kg) the peak plasma concentration was (0.83 ng/ml) lower than that observed in older children (1.26-1.36 ng/ml), but this difference was not statistically significant. Plasma concentrations in the group of smaller children declined significantly faster than in the other weight groups.     

Prolonged elimination of midazolam after i. m. administration

The elimination pharmacokinetics of midazolam after i.m. administration was compared with combined i.m. and i.v. administration in a randomized study of 55 gynaecological patients in outpatient general anaesthesia. Group 1 (n = 40) received midazolam 0.1 mg/kg i.m. as premedication 45 min before induction of general anaesthesia with midazolam 0.3 mg/kg i.v. Group 2 (n = 15) received midazolam 0.1 mg/kg i.m. as premedication 45 min before induction of general anaesthesia with thiopentone 4 mg/kg. Serum midazolam concentration measurements were performed regularly post-induction for 7 h in each patient. The elimination half-life of midazolam after i.m. administration (Group 2) was 6.6 +/- 1.2 h (mean +/- s.e. mean), which was significantly longer (P less than 0.05) than the 3.9 +/- 0.3 h observed after the combined i.m. and i.v. administration of midazolam (Group 1), and significantly longer than 2.9 h obtained from a calculated i.v. administration curve. We postulate a slow i.m. depot release of midazolam, representing the rate-limiting step in the elimination of midazolam after i.m. administration.     

Midazolam and amnesia in pediatric premedication

One hundred and twenty-eight children aged three to ten years, were studied to determine the effect of premedication on amnesia for the preanesthetic period. Four comparable groups were used: A control group, no premedication; oral trimeprazine tartrate 2 mg/kg, methadone 0.1 mg/kg plus droperidol 0.15 mg/kg (T.M.D.); oral midazolam 0.45 mg/kg; intramuscular midazolam 0.15 mg/kg. Amnesia was tested for four pictorial facts, and for induction of anesthesia. For pictorial facts, both routes of midazolam administration gave a sixty percent incidence of amnesia compared with sixteen percent in the control group (p less than 0.001). The T.M.D. premedication provided a forty-three percent incidence, also better than the control group (p less than 0.05). Induction was remembered by fifty percent of the midazolam children compared with sixty-six percent of the T.M.D. group (p greater than 0.05) and eight-one percent of the control group (p less than 0.05). The potential advantages of amnesia in pediatric premedication are discussed.