Effect of oral midazolam premedication on the awakening concentration of sevoflurane, recovery times and bispectral index in children.

BACKGROUND: We sought to determine the influence of preoperative oral midazolam on: (i) measures of anaesthetic emergence; (ii) recovery times and (iii) intraoperative bispectral index (BIS) measurements during sevoflurane/N2O anaesthesia in paediatric patients. METHODS: Fifty-two patients, aged 1-10 years, ASA I-II, were enrolled in a prospective double-blinded study. Patients were randomized to receive either midazolam 0.5 mg.kg(-1) (M) or midazolam vehicle (P) as premedication. After inhalation induction and intubation, expired sevoflurane was stabilized at 3% in 60% N2O and the corresponding BIS (BIS I) recorded. At the completion of surgery, sevoflurane was stabilized at 0.5% and the BIS (BIS E) again recorded. Awakening time, expired sevoflurane/N2O awakening concentrations and recovery times were recorded. RESULTS: There were no significant differences between groups in awakening time, sevoflurane or N2O awakening concentrations, time to PACU discharge, time to hospital discharge or in BIS I and BIS E measurements.

The effect of bispectral index monitoring on anesthetic use and recovery in children anesthetized with sevoflurane in nitrous oxide.

UNLABELLED: The utility of bispectral index (BIS) monitoring to guide anesthetic administration has been demonstrated in adults. This prospective, randomized observer-blinded study was designed to evaluate the effect of BIS monitoring on anesthetic use and recovery characteristics in pediatric patients. After data collection in 38 historical controls, 202 patients age 0-18 yr were randomized into one of two groups: standard practice (SP) and BIS guided (BIS). Patients age 0-3 yr undergoing inguinal hernia repair (IH) and patients age 3-18 yr undergoing tonsillectomy and/or adenoidectomy (TA) were selected. All patients were anesthetized with sevoflurane in 60% N(2)O/O(2). Hernia patients also received a caudal epidural anesthetic before surgery. In the BIS group, anesthetic delivery was adjusted in an effort to achieve a target BIS of 45-60 during maintenance and 60-70 during the last 15 min of the procedure. BIS was recorded throughout surgery in all patients, but data were unavailable to the anesthesiologist in the SP group. In the TA patients, BIS monitoring was associated with a significant reduction in end-tidal sevoflurane concentration during maintenance (2.4 +/- 0.6%, SP and 1.8 +/- 0.4% BIS, mean +/- SD) and during the last 15 min of the procedure (2.1 +/- 0.7, SP and 1.6 +/- 0.6, BIS). There was a 25%-40% decrease in measured recovery times. In the patients 0-6 mo of age undergoing IH, sevoflurane concentrations during maintenance (2.0 +/- 0.4% SP, 0.9 +/- 0.8 BIS), during the last 15 min (1.6 +/- 0.4% SP, 0.6 +/- 0.6% BIS), and at the end of the procedure (1.1 +/- 0.6% SP, 0.3 +/- 0.3% BIS) were smaller in the BIS group. Emergence and recovery measures were unaffected by BIS titration. In the children 6 mo-3 yr of age, there were no significant differences between the SP and BIS groups in anesthetic use or recovery measures. IMPLICATIONS: Bispectral index monitoring in children results in less anesthetic use and faster recovery than standard practice.

Postnatal growth curve of the infant with extremely low birth weight who was fed enterally.

The primary objective of this study was the establishment of a postnatal growth curve for the very low-birth-weight infant. Only infants whose size was appropriate for gestational age and whose predominant form of nourishment was enteral were included in the study. Two growth curves were constructed: one for infants weighing less than 900 g (group A, birth weight 799 +/- 79 [SD] g, mean gestational age 26.5 weeks), and one for infants weighing 901 to 1,100 g (group B, birth weight 1,023 +/- 53 [SD] g, mean gestational age 28.5 weeks). Growth was followed over the first 50 postnatal days. Group A infants gained an average of 10.2 g/d overall during the first 50 postnatal days and group B infants gained an average of 17.1 g/d over the same period. Because the major objective of this study was construction of a growth curve for infants weighing less than 900 g, direct comparison is made with the Dancis grid (1948) as this is the only standard for this group. The growth rates of our infants were found to be more than twice that of the original prediction of Dancis.

9-nor-9beta-hydroxyhexahydrocannabinol, a cannabinoid with potent antinociceptive activity: comparisons with morphine.

The effects of (+/-)9-nor-9beta-hydroxyhexahydrocannabinol (beta-HHC) on tail-flick test activity and the accumulation of newly synthesized dopamine and norepinephrine were studied in the male albino mouse. The same parameters were also studied in naloxone-pretreated and morphine-tolerant mice. beta-HHC was about equipotent with morphine in the mouse tail-flick (ED50 = 7.12 mg/kg). The cannabinoid also produced dose-dependent increases in the accumulation of newly synthesized DA and NE. Pretreatment with 2 mg/kg of naloxone antagonized both the tail-flick activity and blocked the increases in catecholamine synthesis produced by beta-HHC. Cross-tolerance between beta-HHC and morphine did not exist in regard to either tail-flick activity or increased catecholamine synthesis. These studies suggest that beta-HHC may share some properties with the narcotic analgesics but that significant differences exist. Furthermore, these studies offer further evidence for the involvement of catecholamine containing neurons in the central mediation of the tail-flick response.

The correlation between antinociceptive activity of narcotics and their antagonists as measured in the mouse tail-flick test and increased synthesis of brain catecholamines.

The effects of several narcotics, narcotic antagonists-analgesics and narcotic antagonists on the synthesis of dopamine and norepinephrine in mouse brain were estimated and related to their activity in the tail-flick test. Catecholamine synthesis was estimated by measuring the accumulation of 3H-dopamine and 3H-norepinephrine formed from an injection of 3H-tyrosine. Morphine produced dose-related increases in both tail-flick activity and catecholamine synthesis. Each of the narcotic analgesics produced a significant increase in catecholamine synthesis 30 minutes after the subcutaneous injection of an antinociceptive dose (ED80). Under these same conditions, drugs which are inactive in the tail-flick test, such as pentazocine, produced a decrease in catecholamine synthesis and cyclazocine; naloxone and naltrexone were without significant effect. However, cyclazocine, which was inactive in the tail-flick test and did not alter catecholamine synthesis 30 minutes after administration, demonstrated tail-flick activity and produced increased catecholamine synthesis 2 minutes after its administration. Morphine was devoid of either activity 2 minutes after administration. Similarly, at 2 hours after the administration of a dose of morphine (10 mg/kg) that was active in the tail-flick test and increased catecholamine synthesis at 30 minutes, neither tail-flick activity nor increased catecholamine synthesis was observed. Naloxone blocked both the antinociceptive action and the increased catecholamine synthesis produced by both morphine and methadone. The results of these studies indicate that a correlation exists between tail-flick activity of narcotic-like drugs and their ability to increase catecholamine synthesis. These data support the hypothesis that brain catecholamines may be involved in the central mediation of the tail-flick response and other actions of the narcotic analgesics.