Dynamics of MLAEP changes in midazolam-induced sedation

This study aimed at assessing the effects of midazolam (MDZ) sedation on auditory brainstem (BAEP) and middle latency (MLAEP) evoked potentials in intensive care conditions. Ten ventilated comatose patients were receiving an intravenous MDZ bolus dose (0.2 mg/kg) followed by a 2 h continuous infusion (0.1 mg/kg/h). MLAEPs and BAEPs elicited by clicks (90 dB HL+masking) were simultaneously and continuously monitored during the first 6 h and for 30 min the next morning. We found no effect of MDZ sedation on BAEPs. Only MLAEP components were modified. However, none of the patients presented any total abolition of the MLAEPs. Bolus injection led to very early alteration of cortical responses, beginning after 5 min and lasting almost 1 h (maximum Pa latency increase, 3.1 ms; maximum Pa-Nb amplitude decrease, 46%). During continuous infusion, MLAEPs remained slightly, although significantly, altered (Pa latency, +1.3 ms; Pa-Nb amplitude, 27%). The Nb wave seemed to be modified earlier and to return to normality later than the Pa wave. These findings incite a careful interpretation of MLAEP tracings acquired during the first hour following MDZ bolus injection. If possible, MDZ should be administered as continuous infusion for reliable interpretation of evoked potential changes in intensive care unit, or during surgery.     

EFFECTIVE, FIELD-BASED INHALATION ANESTHESIA FOR ICE SEALS

Thirty five adult crabeater seals ( Lobodon carcinophaga ) were anesthetized with combinations of the sedative midazolam and the gaseous anesthetic isoflurane during three research cruises to the Antarctic Peninsula (∼67°S, 67°W) in the austral winters of 2001 and 2002. Modifications were required to gas anesthetic equipment to achieve field portability and sufficient heating to allow operations in temperatures as low as -20°C. Seals were sedated with an average intramuscular dose of midazolam of 0.55 ± 0.14 mg/kg delivered via a pole syringe ( n = 32). One seal was not given midazolam and two seals were injected intravenously. Premedication with midazolam provided moderate sedation, making capture and masking practical and safe. Mean induction time with isoflurane was 8 ± 4.8 min. Mean maintenance concentration over the anesthetic period were 2.3%± 0.9% of isoflurane. Average recovery time was 18.2 ± 8.8 min. No substantial difficulties were experienced and anesthetics were easily managed. This drug combination and the use of modified, heated equipment provide an effective anesthetic procedure for crabeater seals.     

Conscious Sedation Procedures Using Intravenous Midazolam for Dental Care in Patients with Different Cognitive Profiles: A Prospective Study of Effectiveness and Safety

The use of midazolam for dental care in patients with intellectual disability is poorly documented. This study aimed to evaluate the effectiveness and safety of conscious sedation procedures using intravenous midazolam in adults and children with intellectual disability (ID) compared to dentally anxious patients (DA). Ninety-eight patients with ID and 44 patients with DA programmed for intravenous midazolam participated in the study over 187 and 133 sessions, respectively. Evaluation criteria were success of dental treatment, cooperation level (modified Venham scale), and occurrence of adverse effects. The mean intravenous dose administered was 8.8±4.9 mg and 9.8±4.1 mg in ID and DA sessions respectively (t-test, NS). 50% N₂O/O₂ was administered during cannulation in 51% of ID sessions and 61% of DA sessions (NS, Fisher exact test). Oral or rectal midazolam premedication was administered for cannulation in 31% of ID sessions and 3% of DA sessions (p<0,001, Fisher exact test). Dental treatment was successful in 9 out of 10 sessions for both groups. Minor adverse effects occurred in 16.6% and 6.8% of ID and DA sessions respectively (p = 0.01, Fisher exact test). Patients with ID were more often very disturbed during cannulation (25.4% ID vs. 3.9% DA sessions) and were less often relaxed after induction (58.9% ID vs. 90.3% DA) and during dental treatment (39.5% ID vs. 59.7% DA) (p<0.001, Fisher exact test) than patients with DA. When midazolam sedation was repeated, cooperation improved for both groups. Conscious sedation procedures using intravenous midazolam, with or without premedication and/or inhalation sedation (50% N₂O/O₂), were shown to be safe and effective in patients with intellectual disability when administered by dentists.     

Propofol infusion for sedation in the intensive care unit: preliminary report.

Propofol (2,6,di-isopropylphenol) was given by continuous intravenous infusion to provide sedation after cardiac surgery in 30 patients and its effects compared with those of midazolam given to a further 30 patients. Propofol infusion allowed rapid and accurate control of the level of sedation, which was satisfactory for longer than with midazolam. Patients given propofol recovered significantly more rapidly from their sedation once they had fulfilled the criteria for weaning from artificial ventilation and as a result spent a significantly shorter time attached to a ventilator. There were no serious complications in either group. Both medical and nursing staff considered the propofol infusion to be superior to midazolam in these patients. These findings suggest that propofol is a suitable replacement for etomidate and alphaxalone-alphadolone for sedating patients receiving intensive care.     

Efficiency and safety of inhalative sedation with sevoflurane in comparison to an intravenous sedation concept with propofol in intensive care patients: study protocol for a randomized controlled trial

ABSTRACT: BACKGROUND: State of the art sedation concepts on intensive care units (ICU) favor propofol for a time period of up to 72 h and midazolam for long-term sedation. However, intravenous sedation is associated with complications such as development of tolerance, insufficient sedation quality, gastrointestinal paralysis, and withdrawal symptoms including cognitive deficits. Therefore, we aimed to investigate whether sevoflurane as a volatile anesthetic technically implemented by the anesthetic-conserving device (ACD) may provide advantages regarding 'weaning time', efficiency, and patient's safety when compared to standard intravenous sedation employing propofol. Method/Design This currently ongoing trial is designed as a two-armed, monocentric, randomized prospective phase II studies including intubated intensive care patients with an expected necessity for sedation exceeding 48 h. Patients are randomly assigned to either receive intravenous sedation with propofol or sevoflurane employing the ACD. Primary endpoint is the comparison of the 'weaning time' defined as the time required from discontinuation of the sedating agent until sufficient spontaneous breathing occurs. Moreover, sedation depth evaluated by Richmond Agitation Sedation Scale and parameters of patient's safety (that is, vital signs, laboratory monitoring of organ function) as well as the duration of mechanical ventilation and overall stay on the ICU are analyzed and compared. An intention-to-treat analysis will be carried out with all patients for whom it will be possible to define a wake-up time. In addition, a per-protocol analysis is envisaged. Completion of patient recruitment is expected by the end of 2012. DISCUSSION: This clinical study is designed to evaluate the impact of sevoflurane during long-term sedation of critically ill patients on 'weaning time', efficiency, and patient's safety compared to the standard intravenous sedation concept employing propofol. Trial registration EudraCT2007-006087-30; ISCRTN90609144.     

丙泊酚与咪达唑仑用于全麻后苏醒室躁动疗效的比较

目的:比较丙泊酚及咪达唑仑用于全麻后苏醒室(post-anesthesia care unit,PACU)躁动的疗效。方法:本研究选取2016年11月至2020年4月全麻术后转入PACU后发生中、重度躁动的患者194例,分为丙泊酚组(P组,n=98)、咪达唑仑组(M组,n=96)。P组静脉注射丙泊酚0.5 mg/kg~1 mg/kg,M组静脉注射咪达唑仑0.03 mg/kg。必要时重复给药,直至患者Riker镇静和躁动评分在4分及以下。记录两组患者给药次数、药物起效时间、给药前后Riker评分、PACU停留时间、给药前、末次给药后生命体征及处理方法。结果:首次给药后,两组患者躁动均可得到缓解,Riker评分差异无统计学意义(P>0.05)。P组48例患者缓解后躁动再次加重,重复给药后38例可渐缓解,另10例仍需制动。M组12例患者躁动缓解后再次加重,重复给药后均可渐缓解。两组患者首次给药后躁动缓解后再次加重的症状差异具有统计学意义(P<0.05),PACU停留时间差异无统计学意义(P>0.05)。其中P组7例患者重复给药后呼吸抑制予托下颌面罩供氧后可快速缓解,M组重复给药后3例患者呼吸抑制需放置口咽通气道。结论:咪达唑仑用于PACU躁动较丙泊酚不易反复发作,但重复给药后引起的呼吸抑制需被重视。     

Low-dose propofol infusion for sedation during local anesthesia

The safety and efficacy of lose-dose propofol for sedation were investigated on 90 consenting patients who had undergone surgical procedures with local anesthesia. After being premedicated with intravenous midazolam 0.05 mg.kg(-1), all patients were randomly divided into two groups and received intravenously either a loading dose of propofol 0.8 mg.kg(-1) followed by a continuous infusion of propofol 30 microg.kg(-1)min(-1) (propofol group) or an equivalent volume of saline (placebo group) during operation. Study groups were compared with respect to the level of sedation, hemodynamic variables, oxygen saturation, and the incidence of intraoperative side effects. In addition, the discharge time and the satisfaction of both patients and surgeons with this sedative technique were assessed. Propofol reduced patients' discomfort and lowered their arterial pressure and heart rate during the infiltration of local anesthetics. It also promoted an adequate level of sedation without clinically significant oxygen desaturation in the intraoperative period. Surgeons and patients in the propofol group showed a higher level of satisfaction than those in the placebo group. There was no significant difference between the two groups with regard to the incidence of adverse effects and the discharge time. In conclusion, it was found that the use of low-dose propofol infusion was a safe and effective sedative technique for local anesthesia.     

Nociceptive Transmission to Rat Primary Somatosensory Cortex – Comparison of Sedative and Analgesic Effects

CO₂-laser C-fibre evoked cortical potentials (LCEPs) is a potentially useful animal model for studies of pain mechanisms. A potential confounding factor when assessing analgesic effects of systemically administered drugs using LCEP is sedation. This study aims to clarify: 1) the relation between level of anaesthesia and magnitude of LCEP, 2) the effects of a sedative and an analgesic on LCEP and dominant EEG frequency 3) the effects of a sedative and analgesic on LCEP when dominant EEG frequency is kept stable. LCEP and EEG were recorded in isoflurane/nitrous-oxide anaesthetized rats. Increasing isoflurane level gradually reduced LCEPs and lowered dominant EEG frequencies. Systemic midazolam (10 μmol/kg) profoundly reduced LCEP (19% of control) and lowered dominant EEG frequency. Similarly, morphine 1 and 3 mg/kg reduced LCEP (39%, 12% of control, respectively) and decreased EEG frequency. When keeping the dominant EEG frequency stable, midazolam caused no significant change of LCEP. Under these premises, morphine at 3 mg/kg, but not 1 mg/kg, caused a significant LCEP reduction (26% of control). In conclusion, the present data indicate that the sedative effects should be accounted for when assessing the analgesic effects of drug. Furthermore, it is suggested that LCEP, given that changes in EEG induced by sedation are compensated for, can provide information about the analgesic properties of systemically administrated drugs.     

Sedative and cardiovascular effects of midazolam in swine.

The ability to reliably produce sedation in swine is hampered by the paucity of agents available. This project examined the use of a new water soluble benzodiazepine, midazolam, as a sedative in swine. Echocardiographic studies were performed on thirty 23 to 30 kg Yorkshire swine before and 20 minutes after each animal received a single intramuscular dose of 100 micrograms/kg midazolam. Heart rate and respiratory rate decreased significantly compared to nonsedated values (93 +/- 7 versus 117 +/- 2 bpm and 10 +/- 1 versus 20 +/- 1 breaths/min, respectively [p less than 0.05]). However, there was no effect on left ventricular fractional shortening (29.9 greater than 0.05 versus 29.5 +/- 0.05% [p greater than 0.05]). An additional five pigs were instrumented for a dose response study in order to collect hemodynamic data and blood gas values at baseline, and 15 min after the intravenous administration of incremental doses of midazolam (100 to 1,000 micrograms/kg). Despite a significant decrease in heart rate and respiratory rate, cardiac output, blood gases, and pH remained within normal ranges at all dosage levels. Both routes of administration produced sedation for 20 min in all animals. Midazolam is an effective swine sedative that is associated with stable cardiac function.     

The clinical outcome of abdominoplasty performed under conscious sedation: increased use of fentanyl correlated with longer stay in outpatient unit

The objective of this study was to present data supporting the effectiveness of performing mini and full abdominoplasties under conscious sedation with local anesthesia. The authors performed 20 such operations between 1994 and 1996, using a combination of midazolam (Versed) and fentanyl instead of general anesthesia (without an anesthesiologist or nurse anesthetist present). At 5- to 10-minute intervals, the surgeon would order the injection of 1 cc (1 mg/ml) of midazolam and 1 cc (50 microg/ml) of fentanyl. The amount and the interval varied based on the patient's level of sedation. Blood pressure, oxygen saturation, and the patient's response to verbal and physical stimuli were used to assess the sedation level. Average operating time was 147.5 minutes, and mean length of stay in the outpatient recovery room was 235.5 minutes. The average amounts of midazolam and fentanyl used were 9.4 mg (6 to 12.5 mg) and 532 microg (300 to 800 microg), respectively. The average age of patients in this group was 41.7 years (28 to 63 years). Nineteen patients were discharged the same day. There were no surgical complications and no complication related to the sedation (such as respiratory or cardiac compromise). The average follow-up of these patients was 1.2 years (range, 3 to 21 months). Correlation coefficient rates and regression rates were calculated. The longer the procedure, the more midazolam was used intraoperatively (r = 0.5, p = 0.03). However, there was no correlation between the length of the procedure and the amount of fentanyl used. Rather, there was a positive correlation demonstrating that patients who received more fentanyl stayed longer in the outpatient recovery area after surgery (r = 0.6, p < 0.01). The age of the patients and the amount of midazolam did not correlate with how fast they went home from the outpatient area. In conclusion, full and mini abdominoplasties can be performed safely using conscious sedation without compromising patient care or surgical outcome. Second, the survey revealed that patient satisfaction with these procedures performed under conscious sedation was very high. Third, the increased use of fentanyl, not midazolam, resulted in a longer stay in the outpatient unit after surgery. Nausea is a known side effect of narcotic analgesics, and it correlated with a higher dose of fentanyl administration in the patients. The authors are now routinely administering a dose of either droperidol or odansetron (Zofran) preoperatively (both are antiemetics). Previously, the ratio of midazolam and fentanyl injection was 1:1 every 5 to 10 minutes, but now it is 2: 1 to 4: 1 every 5 to 10 minutes (a smaller dose of fentanyl is administered). The conscious sedation technique should be an option for patients and plastic surgeons in academic and community hospital settings if they desire.     

Intranasal midazolam in piglets: pharmacodynamics (0.2 vs 0.4 mg/kg) and pharmacokinetics (0.4 mg/kg) with bioavailability determination

Intranasal midazolam was studied in two series of piglets: series 1, n = 20 (18 +/- 3 kg), a randomized double blind pharmacodynamic study to compare doses of 0.2 mg/kg and 0.4 mg/kg; series 2, n = 9 (42 +/- 8 kg), a pharmacokinetic study with a 0.4 mg/kg dose administered either intravenously (i.v.) or intranasally (i.n.) in a cross-over protocol with a one-week wash-out period between each. In series 1, midazolam caused significant anxiolysis and sedation within 3 to 4 min, without a significant difference between 0.2 and 0.4 mg/kg doses for any of the studied parameters. In series 2, after intranasal midazolam administration of 0.4 mg/kg, plasma concentrations attained a maximum (Cmax) of 0.13 +/- 0.04 mg/l at 5 min (median Tmax) and remained higher than 0.04 mg/l until 60 min. The bioavailability factor (F) in this study was F = 0.64 +/- 0.17 by the intranasal route. The terminal half-life (T1/2 lambda z) = 145 +/- 138 min was comparable with the i.v. administration half-life (158 +/- 127 min). In conclusion, optimal intranasal midazolam dose in piglets was 0.2 mg/kg, which procures rapid and reliable sedation, adapted to laboratory piglets.     

Comparison of midazolam and diazepam for sedation during plastic surgery

A randomized double-blind study was designed to compare midazolam, a rapid-acting water-soluble benzodiazepine, with diazepam for sedation when administered as an adjuvant to ketamine during local anesthesia. In the preliminary dose-ranging study, midazolam (0.05 to 0.15 mg/kg IV) was found to produce a spectrum of central nervous system activity (e.g., sedation, amnesia) that was similar to diazepam (0.1 to 0.3 mg/kg IV). However, the slope of midazolam's dose-response curve for sedation appeared to be steeper (i.e., a narrower therapeutic dosage range). In a comparative evaluation of their relative sedative-amnestic properties and recovery characteristics, the median effective doses of the two benzodiazepines were compared. Midazolam (0.1 mg/kg IV) was found to produce more profound sedation and amnesia than diazepam (0.2 mg/kg IV). Midazolam was associated with significantly less pain on injection and a lower incidence of postoperative venoirritation. Overall patient acceptance was higher with midazolam compared to diazepam. Finally, recovery characteristics were similar for the two benzodiazepines in our outpatient setting.     

Effect of midazolam and butorphanol premedication on inhalant isoflurane anesthesia in mice

Isoflurane is a representative inhalant anesthesia used in laboratory animals. However, isoflurane mediates respiratory depression and adverse clinical reactions during induction. In the present study, we established a novel balanced anesthesia method in mice that combined isoflurane anesthesia with midazolam and butorphanol (MB). Thirty-four male C57BL/6J mice received either isoflurane alone or isoflurane with an intra-peritoneal MB premedication (3 mg/kg midazolam and 4 mg/kg butorphanol). The minimum alveolar concentration (MAC) in each group was evaluated. Induction time and adverse clinical reactions were recorded in each group. Core body temperature, heart rate, respiratory rate, and oxygen saturation (SPO₂) were assessed before and for 1 h after induction. Premedication with MB achieved a significant reduction in MAC compared with isoflurane monoanesthesia (isoflurane, 1.38 ± 0.15%; isoflurane with MB, 0.78 ± 0.10%; P<0.05). Induction time was significantly shortened with MB premedication, and adverse reactions such as excitement or incontinence were observed less frequently. Furthermore, isoflurane anesthesia with MB premedication caused increase of respiratory rates compared to isoflurane monoanesthesia. No significant decrease of SPO₂ was observed in MBI anesthesia, while a decrease in SPO₂ was apparent with isoflurane monoanesthesia (baseline, 98.3% ± 1.1; 10 min after induction, 91.8 ± 6.4%; P<0.05). In conclusion, premedication with MB was effective for the mitigation of respiratory depression induced by isoflurane in mice, with rapid induction and fewer adverse clinical reactions.     

Changes in minimal alveolar concentration of isoflurane following treatment with medetomidine and tiletamine/zolazepam, epidural morphine or systemic buprenorphine in pigs

The aim of this study was to determine the changes in minimal alveolar concentration (MAC) of isoflurane after treatment with medetomidine and tiletamine/zolazepam (MTZ), epidural morphine or systemic buprenorphine in 11 healthy crossbred pigs. The first part of this study was to measure the baseline values in pigs induced with isoflurane (5%) by face mask and maintained with isoflurane in air and oxygen for 2 h (ISO). Baseline isoflurane MAC was determined using mechanical stimulation. Thereafter, each pig was randomly chosen for a crossover test in which the same animal received three different treatments with at least one week in between treatments. The three treatments were as follows: induction of anaesthesia with medetomidine (0.05 mg kg(-1)) and tiletamine/zolazepam (2.5 mg kg(-1) each) given intramuscularly (MTZ); MTZ followed by epidural morphine (0.1 mg kg(-1); MTZ/M); and MTZ followed by intramuscular buprenorphine (0.1 mg kg(-1); MTZ/B). All pigs were maintained with isoflurane in oxygen and air for 2 h and their lungs were mechanically ventilated. The end-tidal isoflurane concentration, respiratory rate, inspiratory and expiratory O2 and CO2 concentrations, heart rate (HR) and arterial blood pressure were recorded every 10 min. Arterial blood gases were analysed every 20 min. Among the treatment groups, differences in isoflurane MAC were tested using GLM and Tukey's method for further comparison; P < 0.05 was adopted as significant. Isoflurane MAC was 1.9 +/- 0.3%. MTZ reduced isoflurane MAC to 0.6 +/- 0.1%. Additional morphine or buprenorphine reduced the MTZ isoflurane MAC further to 0.4 +/- 0.2 and 0.3 +/- 0.1%, respectively. During MTZ, MTZ/M and MTZ/B mean arterial blood pressure was higher and the alveolar-arterial oxygen tension difference was lower compared with ISO. In conclusion, induction of anaesthesia with MTZ reduced the isoflurane MAC in pigs by 68%. Additional epidural morphine or systemic buprenorphine decreased MTZ isoflurane MAC by 33 and 50%, respectively.     

An outcome study comparing intravenous sedation with midazolam/fentanyl (conscious sedation) versus propofol infusion (deep sedation) for aesthetic surgery

The purpose of this study was to determine the differences in measurable outcomes following aesthetic procedures performed under intravenous sedation with incremental doses of midazolam and fentanyl and those performed under propofol infusion. The authors' hypothesis was that the differences in these outcome parameters are not significant between these intravenous sedation protocols. All intraoperative and perioperative records of 84 consecutive patients having aesthetic surgery under a conscious sedation protocol using incremental doses of intravenous midazolam and fentanyl were retrospectively reviewed and compared with the records of a second group of 85 patients having aesthetic surgery under a deep sedation regimen based primarily on propofol infusion. All procedures were hospital based and performed by two surgeons. Twenty-eight different parameters were examined by chart review. In addition, a patient questionnaire was used to assess patient satisfaction and patient recall of operative and perioperative pain, anxiety, nausea, and vomiting. Multivariate statistical analysis was conducted. The two sedation groups were similar with regard to aesthetic procedures performed and patient demographics. The mean duration of operative time was statistically equivalent (152 minutes and 153 minutes). In both groups, there were minor adverse intraoperative events reported but no significant complications. Transient hypotension was more common in the propofol infusion group (12.9 percent versus 2.4 percent, p = 0.018), but no patient required intervention beyond reducing the sedative agent or increasing intravenous fluids. The amount of supplemental fentanyl given intraoperatively was significantly higher in the group whose primary agent for sedation was propofol infusion than the group who received midazolam/fentanyl (209 mug and 143 mug, respectively). The overall questionnaire response rate was 80 percent for both groups. The midazolam/fentanyl sedation group had more recall of "unpleasant intraoperative events" (17 percent versus 3 percent, p = 0.007). However, both groups had low recall of intraoperative pain, anxiety, and nausea. The propofol infusion group experienced significantly more nausea in the recovery room (p = 0.002), nausea at the time of discharge (p = 0.009), and nausea the evening after the operation (p = 0.013). Greater than 90 percent of the patients in both groups would have the same anesthetic in the future rather than undergo general anesthesia. Patient safety, outcomes, and satisfaction are similar in plastic surgery procedures performed under sedation protocols using either incremental doses of midazolam and fentanyl or propofol infusion. All operative and postoperative outcomes for pain, anxiety, and vomiting were similar in the two groups except for immediate postoperative nausea, which was higher in the propofol infusion group. The overall satisfaction of patients undergoing plastic surgery procedures under these intravenous sedation protocols appears very high.     

小剂量右美托咪定用于局麻下玻璃体切割术的镇静效果观察

目的：探讨右美托咪定用于局麻下玻璃体切割术的镇静效果。方法：选择拟在局麻监测下行玻璃体切割术患者50 例为研究对象,年龄20-72岁,ASA 分级Ⅱ级~Ⅲ级,随机分为右美托咪定组（D组）和咪达唑仑组（M 组）,每组25 例。D组患者于术前10min 静脉泵注右美托咪定0.5 滋g/kg,后以0.2-0.4 μg/kg.h 的速度持续输注,M组术前10 min 缓慢静脉注射咪达唑仑0.02 mg/kg,术中按需静注0.5 mg/ 次。维持VAS 评分≤ 4 分,Ramsay评分2-4 分。记录和比较两组患者术中血压、心率、呼吸的变化、辅助用药及患者对镇静效果的满意度。结果：给药后,M组T5时点MAP较T0显著下降（P〈0.05）,D组T10及以后各时点MAP 较T0显著下降（P〈0.05）;D 组T5及以后各时点BP 较T0显著下降（P〈0.05）,但组间及M 组组内BP 比较差异无统计学意义（P〉0.05）;M 组T30时点HR 较T0 显著下降（P〈0.01）,而在T5时,组间比较差异有统计学意义（P〈0.01）,即D 组下降更为显著。给药后各时点,D 组VAS 评分均显著低于M组（P〈0.05）,30 min 时达最低。两组Ramsay镇静评分给药后5 min 均达2 级以上,与给药前比较均显著升高（P〈0.05）,D组给药后30 min 及以后各时点Ramsay镇静评分均显著高于M组（P〈0.01）。给药后各时点,两组组内和组间SPO2和RR 比较均无统计学差异（P〉0.05）。D 组患者满意度较M组更高（P〈0.05）。结论：小剂量右美托咪定用于玻璃体切割术可使患者血流动力学平稳,镇静效果良好,疼痛感觉减轻,舒适度提高。     

Critical closing pressure during midazolam-induced sleep

The critical closing pressure (Pcrit) is the airway pressure at which the airway collapses and reflects the anatomical contribution to the genesis of obstructive sleep apnea. Pcrit is usually determined during non-rapid eye movement sleep at night, but has been determined under midazolam sedation during the day in the absence of sleep stage monitoring. Indeed, little is known about the effects of midazolam on sleep architecture. Moreover, deeper sedation with midazolam can decrease upper airway muscle activity and increase collapsibility compared with natural sleep. Pcrit under sedation has not been systematically compared with the usual method performed during natural sleep. Therefore, this study aimed to test the hypothesis that Pcrit following low doses of midazolam during the day would be comparable to Pcrit measured during natural sleep in the same patient. Fifteen men (age 54 ± 10 yr, body mass index 30 ± 4 kg/m(2)) with obstructive sleep apnea underwent a baseline standard overnight polysomnogram (apnea-hypopnea index 38 ± 22 events/h, range: 8-66 events/h), and Pcrit was determined during natural sleep and following midazolam. Sleep induction was obtained with low doses of midazolam (2.4 mg, range 2.0-4.4 mg), and sleep architecture was comparable to natural sleep. Natural sleep and induced sleep Pcrit were similar (-0.82 ± -3.44 and -0.97 ± 3.21 cmH(2)O, P = 0.663) and closely associated (intraclass correlation coefficient = 0.92; 95% confidence interval, 0.78-0.97, P < 0.001). Natural and midazolam-induced Pcrit correlated with obstructive sleep apnea severity, indicating that both Pcrit measures provided meaningful physiological information. Pcrit determined during the day with sleep induction is similar to natural overnight sleep and is a valid alternative approach in which to determine Pcrit.     

USE OF A PETHIDINE AND MIDAZOLAM COMBINATION FOR THE REVERSIBLE SEDATION OF CRABEATER SEALS (LOBODON CARCINOPHAGUS)

Between October and December of 1996–1999, off eastern Antarctica (60°-150°E), we darted 31 crabeater seals with midazolam and pethidine at estimated dose rates of 0.15–0.4 mg/kg and 1–3 mg/kg, respectively. Maximum sedation was reached at 23 ± 9 min (n = 18) and first signs of recovery were noted at 54 ± 24 min (n = 4). Seals greater than 250 kg body-mass were sedated by administration of approximately 90–100 mg midazolam and 600 mg pethidine, but the degree of sedation was unpredictable and did not permit invasive procedures in some cases. Behavior of the seal and adjacent conspecifics affected the success of procedures and our ability to monitor vital signs. Naloxone and flumazenil reversed sedation, making this combination attractive for use in animals adjacent to water. Additional ketamine was administered to two seals, resulting in improved restraint.     

Isoflurane with morphine is a suitable anaesthetic regimen for embryo transfer in the production of transgenic rats

During our initial attempts to produce transgenic rats, we found that an anaesthetic combination typically used for embryo transfer (intramuscular injection of ketamine [90 mg/kg] with xylazine [10 mg/kg]) yielded extensive variation in both the depth and length of anaesthesia. In the present prospective study, we compared the reproductive outcomes afforded by using either isoflurane (5% for induction, 2% for maintenance, carried in 2 l/min of oxygen) with morphine (5 mg/kg s.c., given immediately after isoflurane induction) or ketamine/xylazine in adult (250-300 g), pseudopregnant Sprague-Dawley rats. Each animal was anaesthetized with either isoflurane/morphine or ketamine/xylazine, after which 30 microinjected eggs were transferred into the left uterine horn. The mean pregnancy rate for isoflurane/morphine (15%) was 50% greater than that achieved with ketamine/xylazine (10%). The mean number of live pups (just over five per litter) was comparable for both regimens. All rats given isoflurane/morphine quickly achieved a surgical depth of anaesthesia and experienced a rapid postoperative recovery (3-5 min). In contrast, 25% of rats injected with ketamine/xylazine did not reach a depth of anaesthesia within 10 min that was sufficient for laparotomy, and all that were anaesthetized successfully required an extended postoperative recovery period (60-90 min). These data show that isoflurane/morphine is well tolerated by microinjected embryos and suggest that its use during embryo transfer may provide a means for both reducing the number of pseudopregnant females used and increasing the speed with which rat transgenic projects are completed.     

Immobilisation of free-living Weddell seals Leptonychotes weddellii using midazolam and isoflurane

Eleven lactating female Weddell seals were immobilised using inhaled isoflurane and oxygen, having initially been sedated using an intramuscular injection of midazolam. The seals were selected from colonies in Long Fjord, East Antarctica. Isoflurane was delivered using a precision, out-of-circle vaporiser in a portable, heated, semi-closed circle system anaesthetic machine. Induction time (time from injection of midazolam to detected maximal effect of midazolam) ranged from 12 min to 29 min. The maximal effect of midazolam was assessed as being either moderate sedation (n=9) or heavy sedation (n=2), and the maximal effect of inhaled isoflurane and oxygen was assessed as being light anaesthesia (n=11). The level of chemical restraint achieved using this combination allowed attachment of heart rate monitoring units and collection of biological samples. Recovery time ranged from 1 min to 11 min. The anaesthetic regime proved a practical, safe and reliable method for the immobilisation of lactating Weddell seals under conditions of low environmental temperature.