Bispectral index monitoring does not improve early recovery of geriatric outpatients undergoing brief surgical procedures

PURPOSE: To assess if titration of sevoflurane using the bispectral index (BIS) monitor improves the early and intermediate recovery in geriatric outpatients undergoing brief urologic procedures under general anesthesia without muscle relaxants. METHODS: After a standardized induction with propofol and fentanyl, a laryngeal mask airway was inserted and sevoflurane was administered in combination with 60% nitrous oxide in oxygen for maintenance of anesthesia in spontaneously breathing outpatients. In the Control group (n = 25), sevoflurane and fentanyl were titrated according to standard clinical practice. In the BIS-directed group (n = 25), sevoflurane was titrated to maintain a BIS value between 50 and 60, and supplemental fentanyl, 25 mug iv boluses were administered to treat tachypnea. The intraoperative anesthetic and analgesic requirements, as well as the times to eye opening, removal of the laryngeal mask airway device, response to simple commands, orientation to person and place, and postanesthesia care unit discharge eligibility (fast-track score of 14) were assessed at specific time intervals. RESULTS: The minimum alveolar concentration-hour of sevoflurane (0.25 +/- 0.15 and 0.31 +/- 0.2) and end-tidal concentrations of sevoflurane at the end of surgery (0.3 +/- 0.3 and 0.4 +/- 0.20%) did not differ significantly between the Control and BIS-directed groups, respectively. Although the percentage of patients requiring supplemental boluses of fentanyl was reduced in the BIS-directed group (16 vs 48%, P <0.05), the intraoperative BIS values and recovery times were similar in the two groups. CONCLUSION: In this non-paralyzed elderly outpatient surgery population, the use of BIS monitoring for titrating the maintenance anesthetic (sevoflurane) failed to improve the early recovery process.     

Dexmedetomidine vs midazolam for premedication of pediatric patients undergoing anesthesia

Background: Dexmedetomidine, an α₂‐receptor agonist, provides sedation, analgesia, and anxiolytic effects, and these properties make it a potentially useful anesthetic premedication. In this study, we compared the effects of intranasal dexmedetomidine and midazolam on mask induction and preoperative sedation in pediatric patients. Methods: Ninety children classified as ASA physical status I, aged between 2 and 9, who were scheduled to undergo an elective adenotonsillectomy, were enrolled for a prospective, randomized, and double‐blind controlled trial. All of the children received intranasal medication approximately 45–60 min before the induction of anesthesia. Group M (n = 45) received 0.2 mg·kg^?1 of intranasal midazolam, and Group D (n = 45) received 1 μg·kg^?1 of intranasal dexmedetomidine. All of the patients were anesthetized with nitrous oxide, oxygen, and sevoflurane, administered via a face mask. The primary end point was satisfactory mask induction, and the secondary end points included satisfactory sedation upon separation from parents, hemodynamic change, postoperative analgesia, and agitation score at emergence. Results: Satisfactory mask induction was achieved by 82.2% of Group M and 60% of Group D (P = 0.01). There was no evidence of a difference between the groups in either sedation score (P = 0.36) or anxiety score (P = 0.56) upon separation from parents. The number of patients who required postoperative analgesia was higher in the midazolam group (P = 0.045). Conclusion: Intranasal dexmedetomidine and midazolam are equally effective in decreasing anxiety upon separation from parents; however, midazolam is superior in providing satisfactory conditions during mask induction.     

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).     

Effects of midazolam and diazepam as premedication on heart rate variability in surgical patients

We have examined the effects of midazolam 0.06 mg kg^–1i.m. and diazepam 0.2 mg kg^–1 orally as premedicationon the spectral components of heart rate (HR) variability in24 elderly patients aged 65–87 yr and 24 young patientsaged 18–35 yr undergoing elective surgery. The low-frequency/high-frequency(LF/HF) ratio of HR variability increased after arrival in theoperating room in elderly patients who received no premedication,but not in young patients. In elderly patients who receivedmidazolam or diazepam, the LF/HF ratio did not increase. However,diazepam increased the low-frequency component and the totalpower of HR variability in both young and elderly patients.We conclude that cardiac sympathetic nerve activity increasedafter arrival in the operating room in the elderly, that midazolamor diazepam reduced this increase and that diazepam caused anincrease in the total power of HR variability that has not beenobserved for other agents.     

麻醉前肌注咪唑安定对颈丛神经阻滞时应激反应的影响

目的研究颈丛神经阻滞前肌注咪唑安定对应激反应的影响。方法 60例颈丛神经阻滞女性患者均分为两组:A组于入室后肌注咪唑安定0.08mg/kg,B组不用任何药物。两组于入室后20min均行一针法双侧颈浅丛和单侧颈深丛神经阻滞,局麻药用1%利多卡因加0.25%罗哌卡因混合液20ml。观察两组入室前(T0)、颈丛神经阻滞前(T1)、颈丛神经阻滞后5min(T2)、15min(T3)、25min(T4)SBP、DBP、HR、SBP与HR的乘积(RPP),并检测血糖(Glu)、皮质醇(Cor)及血管紧张素Ⅱ(AT-Ⅱ)。结果 B组T1～T4时各项检测指标均明显高于T0时(P0.05),A组T1～T4时各项检测指标均明显低于B组(P0.05)。结论颈丛神经阻滞前肌注咪唑安定有利于抑制颈丛神经阻滞麻醉后的应激反应。     

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.     

The use of midazolam in premedication

Socio-psychological factors, such as increased anxiety in developed societies and cultures, and separation anxiety, particularly in children, justify the use of premedicants. In addition, the link between a central nervous "anxiety centre" and biochemical stress responses is blocked by an efficient anxiolytic. The elimination half-life of midazolam is longer in the elderly than in the young and in the obese than in the thin, which demands longer intervals between repeated doses in old and fat patients. The hypoxic ventilatory response is depressed in most patients and the ventilatory CO₂ response in patients with chronic pulmonary disorders, which justifies increased monitoring of O₂ saturations. It is important for the choice of dose and for estimating the duration of recovery time to know that midazolam is at least four times as potent as diazepam.     

Fast-track eligibility of geriatric patients undergoing short urologic surgery procedures

Our primary objective was to assess the feasibility of geriatric patients (>65 yr) bypassing the postanesthesia care unit (PACU) after ambulatory surgery. A secondary objective was to compare recovery profiles when using three different maintenance anesthetics. Ninety ASA physical status I--III consenting outpatients (>65 yr) undergoing short urologic procedures were randomly assigned to one of three anesthetic treatment groups. After a standardized induction with fentanyl and propofol, anesthesia was maintained with propofol (75-150 microg center dot kg(-1) center dot min(-1) IV), isoflurane (0.7%-1.2% end tidal), or desflurane (3%-6% end tidal), in combination with nitrous oxide 70% in oxygen. In all three groups, the primary anesthetic was titrated to maintain an electroencephalographic-bispectral index value of 60-65. Recovery times, postanesthesia recovery scores, and therapeutic interventions in the PACU were recorded. Although emergence times were similar in the three groups, the time to achieve a fast-track discharge score of 14 was significantly shorter in patients receiving desflurane compared with propofol and isoflurane (22 +/- 23 vs 33 +/- 25 and 44 +/- 36 min, respectively). On arrival in the PACU, a significantly larger percentage of patients receiving desflurane were judged to be fast-track eligible compared with those receiving either isoflurane and propofol (73% vs 43% and 44%, respectively). The number of therapeutic interventions in the PACU was also significantly larger in the Isoflurane group when compared with the Propofol and Desflurane groups (21 vs 11 and 7, respectively). In conclusion, use of desflurane for maintenance of anesthesia should facilitate PACU bypass ("fast-tracking") of geriatric patients undergoing short urologic procedures. IMPLICATIONS: Geriatric outpatients undergoing brief urologic procedures more rapidly achieve fast-tracking discharge criteria after desflurane (versus isoflurane and propofol) anesthesia. Use of isoflurane was also associated with an increased need for nursing interventions in the early recovery period compared with desflurane and propofol.     

The premedication of cardiac surgical patients

One of four groups of patients was not premedicated; the others received diazepam 10 mg by mouth, diazepam 20 mg by mouth or a combination of pentobarbitone orally and morphine and hyoscine intramuscularly. The cardiovascular and respiratory parameters were studied before and after the premedication and any changes in sedation, apprehension and reaction to pain were noted. The ease of induction of anaesthesia in the four groups was compared. Most of the patients who received the pentobarbitone, morphine and hyoscine combination came to theatre calm, sedated and often asleep. They showed no significant cardiovascular or respiratory depression and the induction of anaesthesia was more satisfactory than in the other groups. Two of the patients who were not premedicated became very agitated in the ward and the remainder of the patients in this group were apprehensive in the anaesthetic room and during induction. The effects of diazepam in the two doses studied were intermediate between those who received the pentobarbitone, morphine and hyoscine and those who were not premedicated.     

Perioperative effects of melatonin and midazolam premedication on sedation, orientation, anxiety scores and psychomotor performance

BACKGROUND AND OBJECTIVE: To compare the perioperative effects of melatonin and midazolam given in premedication, on sedation, orientation, anxiety scores and psychomotor performance. METHODS: Exogenous administration of melatonin not only facilitates the onset of sleep but also improves its quality. A prospective, randomized, double-blind, placebo-controlled study was performed in 66 patients undergoing laparoscopic cholecystectomy. Patients were given melatonin 5 mg, midazolam 15 mg or placebo, 90 min before anaesthesia, sublingually. Sedation, orientation and anxiety were quantified before; 10, 30, 60 and 90 min after premedication; and 15, 30, 60 and 90 min after admission to the recovery room. Neurocognitive performance was evaluated at these times, using the Trail Making A and B and Word Fluency tests. The differences between the groups were analysed by ANOVA. Two-way comparisons were performed by Scheffé analysis. Sedation and amnesia were analysed by the chi2 test. RESULTS: Patients who received premedication with either melatonin or midazolam had a significant increase in sedation and decrease in anxiety before operation compared with controls. After operation, there was no difference in sedation scores of all groups. Whereas, 30, 60 and 90 min after premedication the melatonin and midazolam groups exhibited a significantly poorer performance in Trail Making A and B tests compared with placebo, there were no significant differences among the groups in terms of neuropsychological performance after the operation. Amnesia was notable only in the midazolam group for one preoperative event. CONCLUSION: Melatonin premedication was associated with preoperative anxiolysis and sedation without postoperative impairment of psychomotor performance.     

Oral midazolam premedication in preadolescents and adolescents.

We sought to determine the influence of preoperative oral midazolam on 1) sedation score, 2) measures of anesthetic emergence, 3) recovery times, and 4) bispectral index (BIS) measurements during sevoflurane/N(2)O anesthesia in adolescent patients. Fifty ASA I and II patients 10-18 yr of age were enrolled in a prospective double-blinded study. Patients were randomized to receive either 20 mg of midazolam (M group) or midazolam vehicle (P group) as premedication. Before the induction, sedation scores and BIS values were determined in all patients. After inhaled induction and intubation, expired sevoflurane was stabilized at 3% in 60% N(2)O and the corresponding BIS (BIS I) recorded. Upon completion of surgery, sevoflurane was stabilized at 0.5% and the BIS (BIS E) again recorded. Plasma midazolam levels were measured at the time of BIS I and BIS E. There were no significant differences between groups in awakening time, sevoflurane/N(2)O awakening concentrations, time to postanesthesia care unit discharge, or BIS I and BIS E measurements. Sedation scores and preinduction BIS values were significantly lower in Group M than in Group P, although only 40% of midazolam-treated patients exhibited detectable sedation, with marked interindividual variability in achieved plasma midazolam levels. Detectable preoperative sedation was predictive of delayed emergence. IMPLICATIONS: We demonstrated a measurable sedative effect of oral midazolam in adolescents which correlated with simultaneous bispectral index (BIS) measurement. Considering the overall group, midazolam premedication did not affect intraoperative BIS, emergence times, or recovery times compared with placebo controls. Detectable preoperative sedation, and not merely midazolam administration, was predictive of prolonged emergence.     

The use of midazolam and flumazenil in diagnostic and short surgical procedures

Benzodiazepines, used correctly, provide a relatively safe means of providing sedation in a variety of clinical situations and midazolam, which is shorter acting than other benzodiazepines (BZ), is the drug of choice in ambulatory patients. Flumazenil is a highly effective specific competitive BZ antagonist which provides a safe means of rapidly attenuating or terminating BZ sedation. Its mean half-life is 54 min, and in this contact the optimal dosage is 0.2 to 0.5 mg. Although it reverses sedation and amnesia, there is still a question about whether its efficacy in reversing the respiratory depressant effects of benzodiazepines is adequate. This remains an area of critical debate, as does resedation and also its administration to chronic benzodiazepine users. The use of flumazenil to reverse midazolam-induced sedation introduces, for the first time, the possibility of terminating sedation at a predetermined time. Were it to be adopted routinely, it has major implications for the improvement of patient management affecting all aspects of post-operative care.     

The use of midazolam in diagnostic and short surgical procedures in children

A new technique of sedation for children is described, in which midazolam (0.2 mg.kg^-1) was administered topically by the nasal route, followed by ketamine (9.0 mg.kg^-1) administered rectally in 32 patients breathing air spontaneously. Sedation was good in 23, seven required further ketamine (1.0 mg.kg^-1 i.v.), and in two, halothane was introduced. There was no evidence of severe respiratory depression except during oesophagoscopy. Cardiovascular stability was excellent. Of 21 patients over 5 years old, 19 developed complete and two partial anterograde amnesia for the administration of ketamine and surgery. The major complications were nausea and vomiting (live patients) and salivation (eight patients). The mean recovery time was 40 min (s.d. 33 min). It provided a relatively safe, adaptable, non-invasive method of inducing sedation in children.     

Amnesic effect of oral midazolam as premedication in children]

We evaluated the sedative and amnesic effects of oral midazolam as premedication in children. Sixteen children, aged 4-12 yr, undergoing elective minor surgery were divided into 2 groups. One group received midazolam 0.5 mg.kg-1 with atropine 0.03 mg.kg-1 orally. The other control group received only atropine 0.03 mg.kg-1. There was no significant difference in the sedative scale at induction between the 2 groups. Doll-recall was used to assess the amnesic effects. In the midazolam group, 75% of the children forgot dolls they had seen on entering the operating room. Midazolam produced significant anterograde amnesia but no retrograde amnesia. This result suggests that children who received midazolam as premedication forget unpleasant memories at induction and their postoperative emotional responses are least influenced by their memories. We conclude that oral midazolam 0.5 mg.kg-1 is an effective preanesthetic medication in children.     

Clinical recovery and psychomotor function after brief anesthesia with propofol or thiopental.

Propofol, the new intravenous anesthetic agent, is generally used in outpatient anesthesia with expectations of fast recovery. We assessed recovery from anesthesia in a double-blind, crossover, controlled manner in 12 healthy volunteers using clinical tests during the first hour and several psychomotor tests 0.5, 1, 3, 5, and 7 h after brief anesthesia with propofol (2.5 mg/kg and 1.0 mg/kg 3 min later) or thiopental (5.0 mg/kg and 2.0 mg/kg 3 min later). Subjects were able to respond to command, sit, and stand steadily significantly faster (P less than 0.05) after propofol (time until standing steadily 33 +/- 7 min; mean +/- SD) when compared to thiopental anesthesia (time until standing steadily 62 +/- 29 min; mean +/- SD). Psychomotor performance remained significantly worse (P less than 0.05 to P less than 0.001) compared to control for 1 h after propofol and for 5 h after thiopental anesthesia. We conclude that the rapid and complete recovery makes propofol a suitable anesthetic for patients undergoing brief ambulatory surgery.     

术前口服咪唑安定的遗忘作用与内隐记忆的关系

目的 观察咪唑安定的遗忘作用与内隐记忆的关系,同时调查术前口服咪唑安定有无逆行性遗忘作用,对短期记忆的影响及顺行性遗忘的起效时间和效果。方法 60例择期下腹部及下肢手术病人分为三组,每组20例：A组口服咪唑安定7．5mg;B组口服咪唑安定15mg;C组为对照组。入室后服药,然后行硬膜外腰麻联合麻醉。观察脑电、95％谱边界频率（SEF）和双频谱指数（BIS）;根据国际标准化进行镇静分级与评分;采用图片识记和术后测试模糊辨听率的方法进行记忆与遗忘的调查及内隐记忆调查。结果 （1）A、B两组病人从服药后20分钟开始镇静评分较服药前明显降低并与C组比较差异有显著意义。但A、B两组之间在镇静觉醒评分和镇静开始时间差异无显著意义。（2）术后6小时遗忘率调查,A组服药后30分钟,B组服药后20分钟遗忘率较服药前显著升高,并保持在70％－80％的高水平,两组间差异无显著意义。而C组遗忘率 始终为0。（3）三组间模糊辨听率差异无显著意义。（4）服药期间短期记忆10分钟遗忘率三组均为0。（5）服药后30分钟A、B两组的BIS与SEF均较服药前明显降低,但仍维持在80Hz,两组间差异也无显著意义。结论 术前口服咪唑安定7．5mg,30分钟后即可产生良好的顺行性遗忘作用,增大剂量并未明显提高其疗效。咪唑安定不产生逆行性遗忘作用。药物作用期间即刻记忆完整而长期记忆受损,对记忆的影响仅限于外显记忆而不包括内隐记忆。因此这种遗忘作用尚不能完全达到防止麻醉中知晓的目的。