Propofol/remifentanil vs sevoflurane/remifentanil for long lasting surgical procedures: a randomised controlled trial

We compared the haemodynamics, emergence and recovery characteristics of total intravenous anaesthesia using propofol/remifentanil with sevoflurane/remifentanil anaesthesia, under bispectral index guidance, in 103 patients undergoing surgical procedures lasting > 3.5 h. Time to tracheal extubation was significantly shorter in the propofol group than in the sevoflurane group (mean (SD) 8.3 (3.5) min vs 10.8 (4.6) min, respectively; p = 0.0024), but further recovery was comparable in both groups. There were no significant differences in haemodynamic parameters, intensity of pain or postoperative nausea and vomiting. During and after anaesthesia of comparable depth for long lasting surgical procedures, both propofol/remifentanil and sevoflurane/remifentanil enable haemodynamic stability and fast emergence. The shorter time to extubation in the propofol group does not offer a relevant clinical advantage.     

Comparison of a new composite index based on midlatency auditory evoked potentials and electroencephalographic parameters with bispectral index (BIS) during moderate propofol sedation

BACKGROUND AND OBJECTIVE: Derived parameters of the electroencephalogram and auditory evoked potentials can be used to determine depth of anaesthesia and sedation. However, it is not known whether any parameter can identify the occurrence of awareness in individual patients. We have compared the performance of bispectral index and a new composite index derived from auditory evoked potentials and the electroencephalogram (AAI 1.61) in predicting consciousness, explicit and implicit memory during moderate sedation with propofol. METHODS: Twenty-one patients with spinal anaesthesia received intraoperatively propofol at the age-corrected C(50) for loss of consciousness and were presented test words via headphones. Bispectral index and AAI 1.61 (auditory evoked potentials, AEP-Monitor2) were recorded in parallel as well as the Observer's Assessment of Alertness/Sedation-score. Postoperatively, testing for explicit and implicit memory formation was performed. RESULTS: Bispectral index and AAI 1.61 correlated well with loss of consciousness defined by an Observer's Assessment of Alertness/Sedation-score of 2 (identical P(K) of 0.87), but did not allow a prediction of postoperative explicit or implicit recall. CONCLUSIONS: Both bispectral index and AAI may be indices of depth of sedation rather than indicators of memory formation, which persists during propofol sedation even after loss of consciousness.     

Effects of fentanyl on the incidence of emergence agitation in children receiving desflurane or sevoflurane anaesthesia

BACKGROUND AND OBJECTIVE: In children, emergence agitation frequently complicates sevoflurane and desflurane anaesthesia. The effect of intravenous fentanyl 2.5 microg kg(-1) was examined on the incidence of emergence agitation in children who received desflurane or sevoflurane after midazolam premedication and intravenous thiopental induction. METHODS: One hundred and twenty children (2-7 yr) undergoing adenoidectomy or tonsillectomy, or both, were studied. All children were premedicated orally with midazolam 0.5 mg kg(-1). After intravenous induction with thiopental and atracurium to facilitate endotracheal intubation, patients were randomly assigned to one of four groups: Patients in Groups 1 and 3 received physiological saline solution, whereas patients in Groups 2 and 4 received intravenous fentanyl 2.5 microg kg(-1) during induction. Anaesthesia was maintained with sevoflurane in Groups 1 and 2 and with desflurane in Groups 3 and 4. After discontinuation of the volatile anaesthetic, the times to tracheal extubation and response to verbal stimuli (emergence time), and emergence behaviours were recorded. RESULTS: The time to tracheal extubation was significantly shorter in Groups 3 (5.2+/-1.7 min) and (6.4+/-2.1 min) than in Groups 1 (8.1+/-2.1 min) (P = 0.0001 and 0.006, respectively) and 2 (8.8+/-1.9 min) (P = 0.0001). The emergence time was significantly shorter in Group 3 (10.0+/-3.9 min) than in Groups 1 (13.8+/-4.9 min) (P = 0.017) and 2 (14.9+/-4.1 min) (P = 0.003). The incidence rate of severe agitation was 13% in Groups 1 and 3, and 7 and 10% in Groups 2 and 4, respectively (P > 0.05). CONCLUSIONS: After midazolam premedication and intravenous induction of anaesthesia with thiopental administration of intravenous fentanyl 2.5 microg kg(-1) did not provide any clinically significant benefit on emer gence agitation in children who receive sevoflurane or desflurane anaesthesia.     

吸入麻醉下内隐记忆与脑电双频谱指数的关系

目的 研究相同ＭＡＣ水平的吸入麻醉药对内隐记忆的影响,分析内隐记忆消失的界值。方法 ５４例行择期腹部手术患者,随机分为异氟醚、七氟醚、地氟醚３组（每组１８例）,麻醉采用吸入麻醉复合硬膜外麻醉,每组又依吸入麻醉浓度不同分成３个亚组（每组６例）,吸入麻醉药呼末ＭＡＣ值分别为０．４、０．５、０．６,监测患者入室后、麻醉后、切皮后、术中的双频谱指数（ＢＩＳ）,９５％的谱边缘频率（ＳＥＦ）,调查患者术后８ｈ     

Inhalation anaesthesia is cost-effective for ambulatory surgery: a clinical comparison with propofol during elective knee arthroscopy

BACKGROUND AND OBJECTIVE: Cost consciousness has become increasingly important in anaesthesia as elsewhere in healthcare. Cost-minimization with uncompromised patient safety and quality requires systematic comparisons of alternative techniques. Inhalation anaesthesia with desflurane or sevoflurane is compared in this study with propofol delivered by the target controlled infusion technique. Directly measured drug consumption and costs and emergence times are compared. METHODS: Consumed anaesthetics were measured during elective arthroscopy of the knee, and costs were calculated for ASA I-II patients (n = 102) randomized to 3 groups: one group received anaesthesia using propofol administered by target controlled infusion, the others inhalation anaesthesia with either desflurane or sevoflurane in combination with nitrous oxide. A partial rebreathing system was used with a laryngeal mask airway. Vaporizers were weighed before and after each anaesthetic. RESULTS: Anaesthetic duration, postoperative pain and emesis as well as discharge time did not differ between groups. Inhaled anaesthetic techniques with desflurane or sevoflurane were associated with 2-3 min shorter emergence times (P < 0.001) and approximately 45% lower cost for consumed anaesthetics as compared with a propofol technique based on target controlled infusion. The inclusion of waste costs improved the cost reduction to 55%. CONCLUSIONS: For this patient group, use of inhalation anaesthesia reduced drug costs by half and shortened emergence times compared to target controlled infusion with propofol with equal perioperative patient conditions.     

Comparison of single-breath vital capacity rapid inhalation with sevoflurane 5% and propofol induction on QT interval and haemodynamics for laparoscopic surgery

BACKGROUND AND OBJECTIVE: To compare two techniques to achieve induction of anaesthesia for laparoscopic surgery. A single-breath vital capacity rapid inhalation induction with sevoflurane was compared to intravenous propofol. Their effects on haemodynamics and the QT interval of the electrocardiogram were assessed. METHODS: Forty-four ASA I-II patients scheduled to undergo elective laparoscopic gynaecological surgery were divided into two groups. In the sevoflurane group (Group S, n = 22), general anaesthesia was induced with a single-breath vital capacity rapid inhalation of sevoflurane 5% with nitrous oxide (N2O) 65% in O2 and then anaesthesia was maintained with sevoflurane 1-1.5% with N2O 65% in O2. In the propofol group (Group P, n = 22), general anaesthesia was induced with propofol 2 mg kg(-1) intravenously and maintained with propofol 6 mg kg(-1) h(-1). Systolic, diastolic and mean arterial pressures, heart rate and end-tidal CO2 values were recorded before anaesthesia (basic value), during the induction period (time X), at 10 min (time Y) and at 30 min (time Z) of CO2 insufflation in all patients. QT intervals were calculated using Bazett's equation. RESULTS: Systolic, diastolic and mean arterial pressure values during the induction period (time X) were lower than the basic value in both groups (P < 0.05). In Group S, QTc intervals were significantly longer during the induction period (time X) and at the tenth min of CO2 insufflation (time Y) than Group P (P < 0.05). Five patients at time X and two patients at time Y developed ventricular dysrhythmias, which improved spontaneously in Group S. In Group P, there was no significant difference in QTc intervals and only one patient developed a ventricular dysrhythmia at time Y. CONCLUSIONS: Single-breath vital capacity rapid inhalation induction technique with sevoflurane can cause prolongation of the QT interval and dysrhythmias, compared with induction and maintenance of anaesthesia with propofol in laparoscopic surgery.     

TIVA mit Propofol/Remifentanil oder balancierte Anästhesie mit Sevofluran/Fentanyl bei laparoskopischen Operationen

OBJECTIVE: This study was designed to investigate the differences between TIVA with propofol/remifentanil (P/R) and balanced anaesthesia with sevoflurane/fentanyl (S/F) in gynaecological laparoscopic surgery. Emphasis was put on haemodynamic reaction, recovery profile, postoperative side effects and patient satisfaction. METHODS: Sixty patients were randomly assigned to receive either total intravenous anaesthesia with propofol/remifentanil or anaesthesia with sevoflurane/fentanyl. After premedication (midazolam) and induction of anesthesia (propofol, atracurium) in both groups, either 1 microgram/kg fentanyl (S/F) or 1 microgram/kg remifentanil (P/R) was injected. Anaesthesia was maintained with 0.5 microgram/kg/min remifentanil (reduced to 50% after 5 min) and 0.06 microgram/kg/min propofol (P/R) or 1.7 vol % sevoflurane (S/F). Both groups were mechanically ventilated with 30% oxygen in air. The administration of sevoflurane and the infusion of the anaesthetics were adjusted to maintain a surgical depth of anaesthesia. For postoperative analgesia 1 g paracetamol was administered rectally prior to surgery. After recovery 20 mg/kg metamizol was given intravenously. At the end of surgery the anaesthetics were discontinued and haemodynamics, early emergence from anaesthesia, pain level, frequency of analgesic demand, incidence of PONV, shivering and patient satisfaction were assessed. Parameters were recorded for 24 h postoperatively. RESULTS: Recovery time after propofol-remifentanil anaesthesia was significantly shorter than after administration of sevoflurane and fentanyl (spontaneous ventilation 4.1 vs. 6.3 min, extubation 4.3 vs. 9.3 min, eye opening 4.4 vs 8.2 min, stating name 5.3 vs. 13.2 min, stating date of birth 5.4 vs. 13.3 min). There were no significant differences between the groups in shivering, pain score, analgesic demand and PONV. The S/F group responded to tracheal intubation with significantly higher blood pressure than the P/R group. During maintenance of anaesthesia heart rate in patients with S/F was significantly higher (P/R:HR max +16/-10; S/F:HR max +24/-0.). Measured on a scale (S/F 62%). CONCLUSION: Compared with patients given balanced anaesthesia with sevoflurane and fentanyl, TIVA with propofol and remifentanil proved to be particularly suited for gynaecological laparoscopic surgery. Its major advantages are haemodynamic stability, significantly shorter times of emergence, and the exceptional acceptance by the patients.     

Quality of recovery in children: sevoflurane versus propofol

BACKGROUND: Sevoflurane, with its low pungency and low blood and tissue solubility, is an attractive anaesthetic in paediatric outpatient surgery. Propofol-anaesthesia is recognised for its rapid and clear-headed emergence. This study was designed to compare emergence and recovery characteristics of sevoflurane and propofol anaesthesia for tonsillectomy in children. METHODS: Children aged 3-10 years, undergoing elective tonsillectomy, were randomly assigned to receive propofol (n=25, induction with 3 mg x kg(-1), maintenance with 100-250 microg x kg(-1) min(-1)) or sevoflurane anaesthesia (n=25, induction 7 vol.%, maintenance 2-3 vol.%). Tracheal intubation was performed with alfentanil 20 microg x kg(-1) and atracurium 0.5 mg x kg(-1). Ventilation was controlled to maintain normocapnia and all patients received N2O/O2 (60:40 vol.%) for induction and maintenance of anaesthesia. At the end of surgery infiltration of the operative sites with bupivacaine 2 mg x kg(-1) was provided for postoperative analgesia. Emergence, recovery, discharge times, and incidence of side effects were compared between the two groups. RESULTS: Time to extubation (14 vs 15 min), time to response to simple verbal command (21 vs 21 min) and time to discharge from the recovery room (45 vs 50 min) were similar in the sevoflurane and propofol groups, respectively. There was a significantly greater incidence of postoperative agitation in the sevoflurane group (46%) compared with the propofol group (9%) (P=0.008). This did not, however, delay discharge from the recovery room. The incidence of nausea and vomiting was not significantly different (8% vs 0%; P=0.49). CONCLUSION: In children, recovery from anaesthesia with sevoflurane results in a higher incidence of agitation compared with propofol.     

七氟醚与异氟醚苏醒期熵指数和听觉诱发电位指数的相关性

目的观察七氟醚和异氟醚苏醒期熵指数(RE和SE)与听觉诱发电位指数(AAI)的变化和相关性。方法择期行腹腔镜下胆囊或子宫附件切除术患者30例,随机均分为七氟醚组(S组)和异氟醚组(I组),分别持续吸入2%～3%七氟醚和异氟醚维持麻醉。吸入麻醉药停止后,20min内每隔1分钟记录RE、SE与AAI,并分析其相关性。结果苏醒期RE、SE与AAI均呈逐渐上升趋势,Ⅰ组相关系数分别为0.89和0.91(P<0.05);S组相关系数分别为0.93和0.91(P<0.05)。结论熵指数和AAI均能反映七氟醚和异氟醚苏醒期麻醉深度的变化,两者相关性良好。     

Ondansetron does not modify emergence agitation in children

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

Post-induction alfentanil reduces sevoflurane-associated emergence agitation in children undergoing an adenotonsillectomy

Background: Emergence agitation is a common problem in paediatric anaesthesia, especially after volatile induction and maintenance anaesthesia (VIMA) with sevoflurane. The purpose of this study was to investigate the effect of alfentanil to prevent emergence agitation without delayed recovery after VIMA with sevoflurane in children undergoing an adenotonsillectomy.
Methods: One hundred and five children, aged 3–10 years, were randomly allocated to receive normal saline (control group), alfentanil 10 μg/kg (A10) or 20 μg/kg (A20) 1 min after loss of the eyelash reflex. Anaesthesia was induced and maintained with sevoflurane. Time to tracheal extubation, recovery time, Paediatric Anaesthesia Emergence Delirium (PAED) scale and emergence behaviour were assessed.
Results: The incidence of severe agitation was significantly lower in the A10 and A20 groups compared with those in the control group (11/32 and 12/34 vs. 24/34, respectively) ( P =0.007, 0.006, respectively). PAED scales were significantly different between the three groups ( P =0.008), and lower in the A10 and A20 groups than that in the control group ( P =0.044, 0.013, respectively). However, the incidence of severe agitation and PAED scale was not different between the A10 and the A20 groups. Time to tracheal extubation and recovery time were similar in all three groups.
Conclusion: The administration of alfentanil 10 μg/kg after induction of anaesthesia for children undergoing an adenotonsillectomy under VIMA reduced the incidence of emergence agitation without delaying the recovery time or causing significant hypotension.     

Prophylactic use of midazolam or propofol at the end of surgery may reduce the incidence of emergence agitation after sevoflurane anaesthesia

Sevoflurane is associated with a high incidence of emergence agitation in children. Midazolam and propofol have been examined with the aim of reducing emergence agitation after sevoflurane anaesthesia. However the effect of both drugs on emergence agitation is still controversial. Therefore we designed this study to measure the effect of midazolam or propofol at the end of surgery on emergence agitation during the recovery period. One hundred and one children, aged one to 13 years, undergoing strabismus surgery were enrolled in this randomised double-blind study. Anaesthesia was induced and maintained with sevoflurane in N2O/O2. Children were randomly assigned to receive midazolam 0.05 mg/kg (group M, n = 35), propofol 1 mg/kg (group P, n = 31) or saline (group S, n = 35). A four-point scale was used to evaluate recovery characteristics upon awakening and during the first hour after emergence from anaesthesia. The incidence of emergence agitation in group M was 42.9% (15/35), in group P 48.4% (15/31) and in group S 74.3% (26/35). The incidence of emergence agitation in groups M and P was significantly less than in group S. The emergence time was prolonged for patients in groups M and P compared to group S. There was no significant difference in the incidence of emergence agitation or in emergence times between the groups P and M. We conclude that propofol or midazolam administration before the end of surgery may be effective in reducing the incidence of emergence agitation in children undergoing strabismus surgery under sevoflurane anaesthesia.     

不同剂量右美托咪啶对腹腔镜卵巢囊肿剥除术患者七氟醚用量的影响

目的 评价不同剂量右美托咪啶对腹腔镜卵巢囊肿剥除术患者七氟醚用量的影响.方法 择期全麻下行腹腔镜卵巢囊肿剥除术患者80例,ASA分级Ⅰ或Ⅱ级,年龄25～50岁,体重指数18～ 25 kg/m2,采用随机数字表法,将患者随机分为4组(n=20):对照组(C组)于切皮前10 min静脉输注生理盐水20 ml;低、中和高剂量右美托咪啶组(DL组、DM组和DH组)于切皮前10 min分别静脉输注右美托咪啶0.3、0.6、0.9 μg/kg,输注时间10 min.吸入七氟醚维持麻醉,术中维持Narcotrend值40～50.于给予右美托咪啶前即刻(T1)、切皮(T2)、气腹即刻(T3)、气腹后10 min(T4)和术毕(T5)时测定呼气末七氟醚浓度(ETsev),记录单位时间七氟醚用量、苏醒时间和拔除气管导管时间,拔除气管导管后10 min观察躁动发生情况,于入室静卧10 min(T0)、T3～5时采集外周静脉血样,用快速血糖分析仪测定血糖,用放射免疫法测定血清皮质醇浓度.结果 C组、DL组、DM组和DH组单位时间七氟醚用量、T2～5时ETsev、T3～5时血糖和皮质醇浓度依次降低(P＜0.05);与C组比较,DL组、DM组和DH组拔除气管导管时间、苏醒时间缩短,躁动发生率降低(P＜0.05).结论 右美托咪啶可呈剂量依赖性地减少腹腔镜卵巢囊肿剥除术患者七氟醚用量.     

Acupuncture facilitates neuromuscular and oculomotor responses to skin incision with no influence on auditory evoked potentials under sevoflurane anaesthesia

BACKGROUND: More sevoflurane was recently found to be required to prevent movement in response to surgical incision in anaesthetized patients subjected to electro-acupuncture (EA) than to sham procedures. The present study was designed to compare differences in movement, dilatation of the pupils, divergence of the eye axes and activity of auditory evoked potentials (AEPs) between patients given and those not given EA under standardized sevoflurane anaesthesia. METHODS: Neuromuscular, oculomotor and AEP responses to skin incision were assessed with and without a bilateral 2-Hz burst EA in patients under steady-state anaesthesia maintained with 1.8% of sevoflurane. Forty-five healthy patients, scheduled for laparoscopic sterilization, were randomized for EA (n = 22) or sham (n = 23) procedures between induction of anaesthesia and start of surgery. Middle latency AEP activity was recorded and interpreted by the A-line ARX (autoregression with exogenous input) index (AAI). RESULTS: More acupuncture than sham patients were found to respond to skin incision with movement of the neck or limbs (77% vs. 43%; P = 0.021), dilatation of the pupils (77% vs. 39%; P = 0.001) and divergence of the eye axes (72% vs. 39%; P = 0.023), whereas there was no difference in AAI response. CONCLUSION: Electro-acupuncture facilitates physiological responses to nociceptive stimulation under sevoflurane anaesthesia. Differences in neuromuscular and oculomotor responses between acupuncture and sham patients under general anaesthesia are probably not associated with interaction between EA and the depth of anaesthesia, as AEP activity was similar in the two groups.     

Memory priming during light anaesthesia with desflurane and remifentanil anaesthesia

Background: Previous studies of memory priming during anaesthesia with EEGmonitoring have observed implicit memory effects for words presentedduring light and deep anaesthesia with and without surgicalstimulation. We hypothesized that memory priming occurs undereach of five different combinations of anaesthesia and surgery,and no significant differences occur in memory priming amongthe five conditions or between the two test points such as,12 vs 24 h after surgery. Methods: Forty gynaecological patients (aged between 28 and 66 yr, median44.5 yr) were included in the study. They received propofoland remifentanil induction followed by desflurane and remifentanilanaesthesia in conjunction with neuromuscular blocking agents.Each patient was exposed to 60 of 120 nouns in a double-blindrandomized design. These 60 nouns were divided into 5 groupsof 12 words, presented under one of the five different conditions,namely, intubation, skin incision, deep anaesthesia and moderateanaesthesia (both during surgery), and light anaesthesia duringthe emergence phase. The depth of anaesthesia was measured usingthe EEG monitor, Narcotrend^TM. Results: No explicit memories were observed in a free recall or in ayes–no recognition test. A word-stem completion test revealeda significant implicit priming only for light anaesthesia (P< 0.01). No significant differences were detected among thefive conditions. An overall implicit memory effect occurredfor the second test point (P < 0.05). Conclusions: Our hypotheses could not be verified. Implicit memory primingoccurred only under light anaesthesia, when the patients weremost probably conscious. Priming effects may be enhanced afternight's sleep.     

Dexmedetomidine decreases emergence agitation in pediatric patients after sevoflurane anesthesia without surgery

BACKGROUND: The purpose of the present study was to determine whether prophylactic use of 1 microg x kg(-1) dexmedetomidine affected the incidence of emergence agitation (EA) after sevoflurane based anesthesia without surgery in children. METHODS: In a double-blinded trial, 42 children (ASA I-II,18 months to 10 years) undergoing magnetic resonance imaging (MRI) examination were randomly assigned to receive dexmedetomidine 1 microg x kg(-1) iv or placebo after induction of anesthesia. Heart rate (HR), mean arterial pressure (MAP), hemoglobin oxygen saturation (SpO2) were monitored. Anesthesia was induced in all patients, irrespective of group, with 8% sevoflurane in 50-50% O2/N2O and maintained with 1.5% sevoflurane in 50/50% O2/N2O. Agitation parameters were assessed with a 5-point scale and measured every 5 min. Delirium was defined as agitation score of > or =4 for > or =5 min. Anesthesia and procedure times and per- and postoperative side effects were recorded. RESULTS: The HR, MAP, and SpO2, spontaneous arm or leg motion times and purposeful movement times showed no significant differences between the two groups. The time of removing the LMA, and the time of eye opening with verbal stimuli was shorter in group P than the group D (P = 0.007 and P = 0.01). The time of discharge to recovery room and the time of discharge from hospital were similar in the two groups. The mean agitation scores in the dexmedetomidine group were significantly lower than the placebo group except at 30 min (P < 0.0001, P = 0.001, P = 0.002, P = 0.013 and P = 0.001). The incidence of emergence agitation was 47.6% in group P, and 4.8% in group D (P = 0.002). CONCLUSION: We concluded that a 1 microg x kg(-1) dose of i.v. dexmedetomidine reduces EA after sevoflurane anesthesia in children undergoing MRI.     

Relationship between awareness and middle latency auditory evoked responses during surgical anaesthesia

Background. Some studies support the view that meaningful auditoryinput can be processed by the brain during apparent surgicalanaesthesia. Consequently, patients may be able to remembersome information implicitly after anaesthesia as well througha ‘dream-like process’ (subconscious awareness).The aim of this study was to investigate the presence of subconsciousawareness during anaesthesia and to examine its relationshipto the mid-latency auditory evoked responses (MLAERs). Methods. We studied 40 patients, ASA I–II, undergoinglaparoscopic cholecystectomy. General anaesthesia was inducedwith thiopental 5 mg kg^–1, fentanyl 3 µg kg^–1,and vecuronium 0.08 mg kg^–1. For the maintenance of anaesthesia,patients were randomly assigned to one of four anaesthetic regimengroups: sevoflurane+air in oxygen 40%; sevoflurane+nitrous oxide60%; isoflurane+air in oxygen 40%; and isoflurane+nitrous oxide60%. MLAERs were recorded before anaesthesia, at 1 MAC of inhaledanaesthetic and then 30 min after awakening. An audiotape withone of four stories was played immediately after intraoperativeMLAER recording. Explicit and implicit memory was assessed 24h after awakening. Results. None of the patients had explicit recall. One of thepatients from the isoflurane–air group showed implicitmemory of listening to the audiotape. A dream-like process,in which they remembered implicitly the story played duringanaesthesia, occurred in one of the patients from the sevoflurane–nitrousoxide group. In the patients with subconscious awareness, MLAERswere similar to that of the awake state with a Pa latency increaseof less than 8.87. When there was a marked increase in Pa latencyduring anaesthesia, no subconscious awareness was observed.No statistically significant differences were found betweenPa latency before and after anaesthesia. Conclusions. MLAERs may help to predict subconscious cerebralprocessing of auditory inputs during anaesthesia. Br J Anaesth 2003; 90: 630–5     

Rocuronium duration of action under sevoflurane, desflurane or propofol anaesthesia

BACKGROUND AND OBJECTIVE: We conducted a prospective randomized study to evaluate whether the duration of action of a single bolus dose of rocuronium is influenced by maintenance of anaesthesia with sevoflurane, desflurane or propofol infusion. METHODS: Fifty-seven ASA I-II patients undergoing elective abdominal surgery were enrolled in this study. Anaesthesia was induced with thiopental 3-5 mg kg(-1) or propofol 2.5 mg kg(-1) and fentanyl 5 microg kg(-1) and tracheal intubation was facilitated with rocuronium 0.9 mg kg(-1). Thereafter patients were randomly allocated to three different groups to receive sevoflurane, desflurane or propofol for maintenance of anaesthesia. Recovery of neuromuscular function was monitored by single twitch stimulation of the ulnar nerve and by recording the adductor pollicis response using accelerometry. Intergroup recovery times to 5% of control value of single twitch were analysed using analysis of variance with Bonferroni correction. RESULTS: The mean (95% confidence interval) recovery time to 5% of control value of single twitch during desflurane anaesthesia was 90.18 (86.11-94.25) min. Significantly shorter recovery times were observed during sevoflurane or propofol anaesthesia, 58.86 (54.73-62.99) min and 51.11 (45.47-56.74) min, respectively (P < 0.001). There were also significant differences in the recovery time between groups receiving desflurane vs. sevoflurane (P < 0.001) and desflurane vs. propofol (P < 0.001). CONCLUSIONS: Desflurane anaesthesia significantly prolongs the duration of action of rocuronium at 0.9 mg kg(-1) single bolus dose, compared to sevoflurane or propofol anaesthesia maintenance regimens.     

Rapid inhalation induction in children: 8% sevoflurane compared with 5% halothane

Sevoflurane has a lower blood-gas solubility and a less pungent odour than halothane; this may allow more rapid induction of anaesthesia. In a randomized, blinded study, we compared the induction characteristics of maximum initial inspired concentration of 8% sevoflurane and 5% halothane using conventional vaporizers in children aged 3 months to 3 years. There was no statistically significant difference in induction times between the two groups: mean times to loss of consciousness were 1 min 12 s (SD 18 s, range 40 s-1 min 44 s) for sevoflurane and 1 min 16 s (SD 17 s, range 50 s-1 min 52 s) for halothane, although these times were shorter than in previous studies using a gradual increase in vapour concentration. A small number of complications were noted in both groups, although none interfered with induction of anaesthesia. Struggling scores were lower in the sevoflurane group than in the halothane group (chi-square for trends = 6.34, P < 0.02). A significant number (11 of 15) of parents of children in the sevoflurane group who had previous experience of halothane induction preferred sevoflurane (chi-square for trends = 4.03, P < 0.05). We conclude that with this technique, induction was rapid with both sevoflurane and halothane. Our assessment of patient struggling and parents' perceptions suggests that induction with sevoflurane was more pleasant than with halothane.      

Sevoflurane versus propofol for induction and maintenance of anaesthesia with the laryngeal mask airway in children

We compared patient outcomes for propofol vs sevoflurane with the laryngeal mask airway (LMA) using either spontaneous breathing (SB) or pressure controlled ventilation (PCV). One hundred and twenty children undergoing minor surgery below the umbilicus were randomly assigned to receive either (1) propofol 3 mg.kg-1 followed by a maintenance infusion of 5 mg.kg-1.h-1, or (2) induction with sevoflurane 7% followed by maintenance with 1.7%. Following LMA insertion, patients were given atracurium and underwent PCV if surgery was expected to last > or = 30 min. The following assessments were made: time to LMA insertion/removal, airway problems, cardiorespiratory effects and recovery characteristics. The first time insertion success rates were similar, but insertion time was shorter with sevoflurane (115 +/- 67 s vs 252 +/- 107 s, P < 0.0001). One patient coughed during placement, but there were no other problems during any phase of anaesthesia in any group. Heart rate was higher in the sevoflurane group following insertion, during maintenance and emergence (all P < 0.03). There were no differences in blood pressure and oxygen saturation among groups PECO2 in the SB group was unaffected by the agent used. Emergence was more rapid (232 +/- 104 s vs 348 +/- 127 s, P < 0.0001) and postoperative agitation more common (15% vs 0%, P = 0.02) with sevoflurane. There were no differences in the Aldrete scores among groups. Patient outcome was similar for the SB and PCV groups. We concluded that the techniques described here using propofol and sevoflurane are equally suitable for induction and maintenance of anaesthesia with the LMA in children undergoing minor surgery below the umbilicus. Emergence is more rapid, but postoperative agitation more common with sevoflurane.