Intravenous Magnesium Sulfate Administration Reduces Propofol Infusion Requirements during Maintenance of Propofol-N2O Anesthesia: Part I: Comparing Propofol Requirements According to Hemodynamic Responses: Part II: Comparing Bispectral Index in Control and Magnesium Groups

Background: The authors investigated whether an intravenous administration of magnesium sulfate reduces propofol infusion requirements during maintenance of propofol-N2O anesthesia.

Methods: Part I study: 54 patients undergoing total abdominal hysterectomy were randomly divided into two groups (n = 27 per group). The patients in the control group received 0.9% sodium chloride solution, whereas the patients in the magnesium group received magnesium (50 mg/kg as a bolus, then 8 mg [middle dot] kg-1 [middle dot] h-1). To maintain mean arterial blood pressure (MAP) and heart rate (HR) at baseline value, the propofol infusion rate was changed when the MAP or the HR changed. The amount of propofol infused excluding the bolus dosage was divided by patient's body weight and total infusion time. Part II study: Another 20 patients were randomly divided into two groups (n = 10 per group). When the MAP and HR had been maintained at baseline value and the propofol infusion rate had been maintained at 80 [mu]g [middle dot] kg-1 [middle dot] min-1 (magnesium group) and 160 [mu]g [middle dot] kg-1 [middle dot] min-1 (control group), bispectral index (BIS) values were measured.

Results: Part I: The mean propofol infusion rate in the magnesium group (81.81 +/- 13.09 [mu]g [middle dot] kg-1 [middle dot] min-1) was significantly less than in the control group (167.57 +/- 47.27). Part II: BIS values in the control group (40.70 +/- 3.89) were significantly less than those in the magnesium group (57.80 +/- 7.32).     

Ephedrine, dopamine, or doubtamine to treat hypotension with propofol during epidural anesthesia

PURPOSE: To compare the efficacy of ephedrine, dopamine and dobutamine for circulatory support during thoracic epidural anesthesia after anesthetic induction with propofol. METHODS: Forty patients undergoing lobectomy or mastectomy were divided into four groups of 10: a control group received no vasopressor; an ephedrine group received 5 mg ephedrine when the mean arterial pressure (MAP), measured every 2.5 min, decreased by 10% from baseline; dopamine and dobutamine groups received 5 microg x kg(-1) x min(-1) dopamine or 3 microg x kg(-1) x min(-1) dobutamine from five minutes after epidural injection of local anesthetic to the end of tracheal intubation. Anesthesia was induced with 2 mg x kg(-1) propofol. The MAP and heart rate (HR) were measured at baseline, 20 min after epidural injection, three minutes after propofol, and one minute after tracheal intubation. RESULTS: In the control group, MAP and HR decreased from 86+/-9 mmHg, 74+/-8 bpm to 62+/-9 mm Hg; P<0.0001, 60+/-8 bpm; P = 0.0003 after propofol. After tracheal intubation, MAP was restored to (81+/-13 mmHg, 70+/-13 bpm). In the ephedrine, dopamine, and dobutamine groups, MAP and HR remained unchanged during epidural anesthesia and propofol induction. However, after tracheal intubation, MAP and HR increased in the ephedrine (104+/-11 mm Hg; P = 0.004, 87+/-11 bpm; P<0.0001) and dobutamine (117+/-13 mm Hg; P = 0.0005, 100+/-11 bpm; P<0.0001) groups, but not in the dopamine group compared with baseline. CONCLUSION: Dopamine is preferable to ephedrine and dobutamine in providing hemodynamic stability during propofol induction and tracheal intubation following epidural anesthesia.     

Cardiac anesthesia induction by low target plasma concentration setting of propofol using target-controlled infusion

BACKGROUND: Propofol-anesthesia administerd using target-controlled infusion (TCI) has been proposed for cardiac surgery. But, moderate target concentration of propofol during induction using TCI has not been studied in detail. METHODS: Thirty patients scheduled for cardiac surgery under cardiopulmonary bypass (CPB) and TCI propofol anesthesia were randomly divided into two groups to receive a computer-controlled infusion of propofol with target concentrations of 1.5 or 2.0 micro/g x ml(-1) [1.5 microg x ml(-1) group (n=15) and 2.0 microg x ml(-1) group (n=15)]. Mean arterial pressure (MAP), heart rate (HR) and bispectral index scale (BIS) values were recorded at 5 time points during induction of anesthesia. RESULTS: MAP was significantly lower in 2.0 microg x ml(-1) group compared with 1.5 microg x ml(-1) group. In both groups, a rise of BIS value did not occur during tracheal intubation. CONCLUSIONS: We have demonstrated that propofol TCI at a target concentration of 1.5 microg x ml(-1) is effective for hemodynamic stability during induction of anesthesia in patients for cardiac surgery under CPB.     

Total intravenous anesthesia with remifentanil, propofol and cisatracurium in end-stage renal failure

PURPOSE: To compare recovery parameters of total intravenous anesthesia (TIVA) with remifentanil and propofol, hemodynamic responses to perioperative events, and pharmacodynamic parameters of cisatracurium in 22 end-stage renal failure and 22 normal renal function patients. METHODS: Anesthesia was induced with 2-3 mg x kg(-1) propofol and 1 microg x kg(-1) remifentanil and maintained with 75 microg x kg(-1) x min(-1) propofol and propofol initial infusion of 0.2 microg x kg(-1) x min(-1) propofol. Arterial pressure and heart rate were maintained by remifentanil infusion rate adjustments. The first twitch (T1) was maintained at 25% by an infusion of cisatracurium. RESULTS: There was no difference in the time to maintenance of adequate respiration, date of birth recollection, first analgesic administration, between the renal failure (4.8+/-2.5, 7.8+/-3.2, 12.3+/-5.3 min respectively) and the control group (5.2+/-2.8, 8.1+/-3.1, 12.7+/-5.5 min): nor were there any differences in the time to 25% T1 recovery, T1 recovery from 25% to 75%, or cisatracurium infusion rate between the renal failure group (32.1 +/-10.8 min, 18.2+/-5.5 min, 0.89+/-0.29 microg x kg(-1) min(-1) respectively) and the control group (35.9 (7.9 min, 18.4+/-3.8 min, 0.95+/-0.22 microg x kg(-1) x min(-1)). CONCLUSION: End-stage renal failure does not prolong recovery from TIVA with remifentanil and propofol, or the recovery from cisatracurium neuromuscular block.     

Effects of propofol and remifentanil on phrenic nerve activity and nociceptive cardiovascular responses in rabbits.

BACKGROUND: The effects of propofol, remifentanil, and their combination on phrenic nerve activity (PNA), resting heart rate (HR), mean arterial pressure (MAP), and nociceptive cardiovascular responses were studied in rabbits. METHODS: Basal anesthesia and constant blood gas tensions were maintained with alpha-chloralose and mechanical ventilation. PNA, HR, MAP, and maximum changes in HR and MAP (deltaHR, deltaMAP) evoked by electrical nerve stimulation of tibial nerves were recorded. The comparative effects were observed for propofol at infusion rates from 0.05 to 3.2 mg x kg(-1) x min(-1) (group I) and remifentanil from 0.0125 to 12.8 microg x kg(-1) x min(-1) alone (group II), and during constant infusions of propofol at rates of 0.1 and 0.8 mg x kg(-1) x min(-1) (groups III and IV, respectively). Finally, the effect of remifentanil on propofol blood levels was observed (group V). RESULTS: The infusion rates for 50% depression (ED50) of PNA, deltaHR, and deltaMAP were 0.41, 1.32, and 1.58 mg x kg-(1) x min(-1) for propofol, and 0.115, 0.125, and 1.090 microg x kg(-1) x min(-1) for remifentanil, respectively. The ratios for the ED50 values of deltaHR and deltaMAP to PNA were 3.2 and 3.9 for propofol, and 1.1 and 9.5 for remifentanil, respectively. Analysis of the expected and observed responses and isobologrms showed that although their combined effects on PNA, resting HR, and MAP, and deltaMAP were synergistic for deltaHR, they were merely additive. Remifentanil had no effect on propofol blood levels. CONCLUSION: PNA was abolished by propofol and remifentanil, alone and in combination, before significant depression of nociceptive pressor responses occurred. Their combined effects on PNA, HR, MAP, and deltaMAP are greater than additive, ie., synergistic. Unlike propofol, remifentanil obtunded pressor responses more than the resting circulation.     

The effect of remifentanil on cerebral blood flow velocity in children anesthetized with propofol

BACKGROUND: Cerebrovascular stability and rapid anesthetic emergence are desirable features of a neuroanesthetic regimen. In this randomized crossover study the effect of a low-dose remifentanil infusion on cerebral blood flow velocity (CBFV) in children anesthetized with propofol was evaluated. METHODS: Twenty healthy children aged 1-6 years undergoing urological surgery were enrolled. Following face mask induction with sevoflurane, anesthesia was maintained with a standardized propofol infusion. Rocuronium was used to facilitate tracheal intubation and normothermia, and normocapnia were maintained. All children received a caudal epidural block, and a transcranial Doppler probe was placed to measure middle cerebral artery blood flow velocity (Vmca). Each patient received a remifentanil regimen of 0.5 microg x kg(-1) followed by 0.2 microg x kg(-1) x min(-1) in a predetermined order of remifentanil + propofol or propofol alone. Vmca, mean arterial pressure (MAP) and heart rate (HR) were recorded simultaneously at equilibrium with and without remifentanil. RESULTS: The combination of remifentanil and propofol caused an 8.1% decrease in MAP (P = 0.0005) and an 11.8% decrease in HR (P < 0.0001) compared with propofol alone. Vmca was not different between the two groups (P = 0.4041). CONCLUSION: The addition of remifentanil to propofol anesthesia in children causes a reduction in MAP and HR without affecting CBFV. This may imply that cerebral blood pressure autoregulation is preserved in children under propofol and remifentanil anesthesia.     

Effects of low dose ketamine before induction on propofol anesthesia for pediatric magnetic resonance imaging

BACKGROUND: We aimed to investigate effects of low dose ketamine before induction on propofol anesthesia for children undergoing magnetic resonance imaging (MRI). METHODS: Forty-three children aged 9 days to 7 years, undergoing elective MRI were randomly assigned to receive intravenously either a 2.5 mg x kg(-1) bolus of propofol followed by an infusion of 100 microg x g(-1) x min(-1) or a 1.5 mg x kg(-1) bolus of propofol immediately after a 0.5 mg x kg(-1) bolus of ketamine followed by an infusion of 75 microg x kg(-1) x min(-1). If a child moved during the imaging sequence, a 0.5-1 mg x kg(-1) bolus of propofol was given. Systolic and diastolic blood pressures, heart rate, peripheral oxygen saturation and respiratory rates were monitored. Apnea, the requirement for airway opening maneuvers, secretions, nausea, vomiting and movement during the imaging sequence were noted. Recovery times were also recorded. RESULTS: Systolic blood pressure and heart rate decreased significantly in the propofol group, while blood pressure did not change and heart rate decreased less in the propofol-ketamine group. Apnea associated with desaturation was observed in three patients of the propofol group. The two groups were similar with respect to requirements for airway opening maneuvers, secretions, nausea-vomiting, movement during the imaging sequence and recovery time. CONCLUSIONS: Intravenous administration of low dose ketamine before induction and maintenance with propofol preserves hemodynamic stability without changing the duration and the quality of recovery compared with propofol alone.     

Influence of bispectral index monitoring on fentanyl requirements during total intravenous anesthesia for major gynecological surgery]

OBJECTIVE: To determine the influence that bispectral index (BIS) monitoring of hypnosis might have on need for analgesia during surgery under total intravenous anesthesia provided by bolus administration of fentanyl. PATIENTS AND METHOD: Prospective, randomized and partially double-blind study of 40 patients undergoing major gynecological surgery under total intravenous anesthesia with propofol and fentanyl. In the BIS group (n = 20) propofol administration was adjusted to maintain BIS between 40 and 60. In the control group (n = 20) standard doses were given: 10 mg/kg-1/h-1 after anesthetic induction and for 5 minutes, 8 mg/kg-1/h-1 over the next 5 minutes and 6 mg/kg-1/h-1 throughout the rest of the operation. All patients received intravenous bolus administration of 150 or 75 microg of fentanyl to maintain analgesia whenever systolic blood pressure and heart rate increased 20% over baseline. We compared propofol and fentanyl requirements, intraoperative changes in BIS, and awakening from anesthesia. RESULTS: Patient and surgical characteristics were similar in both groups. BIS monitoring allowed propofol administration to be decreased a mean 24% during maintenance of anesthesia, and this in turn was associated with a significant increase in mean dose of fentanyl (415 microg versus 253 microg in the BIS and control groups, respectively; p = 0.01). Mean values of BIS were higher in the BIS group (46.4 versus 42.2; p = 0.04) and patients in the BIS group awoke sooner (in 7.7 min versus 11.1 min; p = 0.01) and tended to report less pain upon arrival at the postanesthetic recovery room, although the difference was not statistically significant. CONCLUSIONS: BIS monitoring of depth of hypnosis can influence requirements for fentanyl during total intravenous anesthesia by bolus dosing for maintenance of analgesia. This is probably due to changes in the administration of propofol made possible by BIS monitoring.     

Bispectral index monitoring is useful to reduce total amount of propofol and to obtain immediate recovery after propofol anesthesia

Bispectral index (BIS) is a processed EEG parameter for assessment of hypnotic effects of anesthetics. We studied whether BIS monitoring can improve recovery from propofol anesthesia and decrease the total amount of propofol needed. Forty-six patients without hypertension and obesity were studied. In the BIS group (n = 20), propofol infusion rate was adjusted to achieve a target BIS value between 40-60, increasing to 65 during the final 10 min of the surgical procedure. In the control group (n = 19), propofol infusion rate was adjusted based only on standard clinical signs. Compared with the control group, patients in the BIS group required lower propofol infusion rates(4.3 +/- 1.1 vs 4.9 +/- 0.8 mg.kg-1.h-1; P < 0.05), and the total amount of propofol decreased significantly (709 +/- 210 vs 914 +/- 326 mg; P < 0.05). BIS monitoring led to immediate recovery after propofol anesthesia. There were no significant differences in the incidence of intraoperative responses between the two groups. BIS monitoring decreased the total amount of propofol and led to immediate recovery after propofol anesthesia. These findings indicate that the use of BIS monitoring may be useful in controlling the infusion rate of propofol during surgery.     

Remifentanil administration during monitored anesthesia care: are intermittent boluses an effective alternative to a continuous infusion?

This randomized, double-blind study was designed to evaluate the analgesic effectiveness and respiratory stability of remifentanil when administered as intermittent bolus injections, a variable-rate infusion, or a combination of a constant basal infusion supplemented with intermittent boluses during monitored anesthesia care (MAC). Forty-five patients undergoing extracorporeal shock wave lithotripsy (ESWL) procedures were randomly assigned to one of the three modes of remifentanil administration. All patients received midazolam 2 mg i.v., followed by a propofol infusion at 50 microg x kg(-1) x min(-1). Two minutes before administering a series of test shock waves: Group I received a remifentanil infusion of 0.1 microg x kg(-1) x min(-1), and a saline bolus (5 mL); Group II received a saline infusion and a remifentanil bolus (25 microg in 5 mL); and Group III received a remifentanil infusion of 0.05 microg x kg(-1) x min(-1), and a remifentanil bolus (12.5 microg in 5 mL). The average pain intensity was scored on an 11-point scale, with 0 = no pain to 10 = severe pain. During the ESWL procedure, pain was treated by increasing the study drug infusion rate by 25%-50% and administering 5-mL bolus injections of the study medication in Groups I (saline) and II (remifentanil 25 microg). In Group III, intermittent 5-mL boluses (remifentanil 12.5 microg) were administered as needed. Patients in Groups II and III reported lower pain scores in response to the test shocks. Significantly more remifentanil was administered in Group I (379 +/- 207 microg) than in Group II (201 +/- 136 microg). However, more interventions were required for the treatment of intraoperative pain in the intermittent bolus group (Group II). When remifentanil is administered as the analgesic component of a MAC technique, these data support the use of intermittent bolus doses (12.5-25 microg) alone or in combination with a basal infusion (0.05 microg x kg(-1) x min(-1)) as alternatives to a variable-rate continuous infusion. IMPLICATIONS: In this study, three different modes of remifentanil administration were used during monitored anesthesia care for extracorporeal shock wave lithotripsy procedures. These results suggest that using intermittent bolus injections of remifentanil (25 microg) or a continuous infusion (0.05 microg x kg(-1) x min(-1)) supplemented with intermittent bolus (12.5 microg) injections may be more effective than a variable-rate infusion of remifentanil during propofol sedation.     

Desflurane reduces the effective therapeutic infusion rate (ETI) of cisatracurium more than isoflurane, sevoflurane, or propofol

PURPOSE: The present study investigated the interaction between the cumulative dose requirements of cisatracurium and anesthesia with isoflurane, sevoflurane, desflurane or propofol using closed-loop feedback control. METHODS: Fifty-six patients (18-85 yr, vitrectomies of more than one hour) were studied. In the volatile anesthetics groups, anesthesia was maintained by 1.3 MAC of isoflurane, sevoflurane or desflurane; in the propofol group, anesthesia was maintained by a continuous infusion of 6-8 mg.kg(-1).hr(-1) propofol. After bolus application of 0.1 mg.kg(-1) cisatracurium, a T1%-level of 10% of control level (train-of-four stimulation every 20 sec) was maintained using closed-loop feedback controlled infusion of cisatracurium. The effective therapeutic infusion rate (ETI) was estimated from the asymptotic steady-state infusion rate Iss. The Iss was derived from fitting an asymptotic line to the measured cumulative dose requirement curve. The ETI of the different groups was compared using Kruskal-Wallis- test, followed by rank sum test, corrected for the number of comparisons, P <0.05 was regarded as showing significant difference. RESULTS: ETI in the isoflurane group was 35.6 +/- 8.6 microg.m(-2).min(-1), in the sevoflurane group 36.4+/- 11.9 microg m(-2).min(-1), in the desflurane group 23.8 +/- 6.3 microg.m(-2).min(-1). The ETI of the volatile anesthetic groups were all significantly lower than the ETI in the propofol group at 61.7 +/- 25.3 microg.m(-2).min(-1) (P <0.002). The ETI in the desflurane group was significantly lower than in all other groups (P <0.02). CONCLUSION: In comparison to propofol, isoflurane, sevoflurane and desflurane reduce the cumulative dose requirements of cisatracurium to maintain a 90% neuromuscular blockade by 42%, 41% and 60%, respectively.     

Propofol-nitrous oxide anesthesia enhances the heart rate response to intravenous isoproterenol infusion

Heart rate (HR) response to IV atropine is attenuated during propofol-nitrous oxide (N(2)O) anesthesia. We studied the effects of propofol-N(2)O anesthesia on isoproterenol-induced HR changes. The control group (n = 15) received no propofol and no N(2)O. Patients in the propofol-N(2)O group (n = 21) received IV propofol 2.5 mg/kg over 1 min followed by a continuous infusion of propofol 10 mg x kg(-1) x h(-1). After tracheal intubation, anesthesia was maintained with propofol 5 mg. kg(-1) x h(-1) and 67% N(2)O in oxygen. All patients in both groups received IV isoproterenol at incremental infusion rates (2.5, 5, 7.5, 10, 12.5, 15, and 17.5 ng x kg(-1) x min(-1) for 2 min at each dose) until HR increased more than 20 bpm from baseline values. At the end of each infusion period, hemodynamic data were collected. The HR response to isoproterenol 7.5 ng. kg(-1) x min(-1) was increased more in the propofol group than in the control group (20 +/- 5 versus 14 +/- 4 bpm; P < 0.05). During the isoproterenol infusion at 10 ng. kg(-1) x min(-1), HR increased by more than 20 bpm in all patients in the propofol group but in only 31% of patients in the control group (P < 0.0001). These results suggest that continuous isoproterenol infusion might be useful when a large dose of atropine is ineffective in restoring normal HR during propofol-N(2)O anesthesia. IMPLICATIONS: We demonstrated that the heart rate response to IV isoproterenol infusion is enhanced during propofol-nitrous oxide anesthesia. This suggests that continuous isoproterenol infusion may be useful when a large dose of atropine is ineffective for restoration of normal heart rate in patients receiving propofol-nitrous oxide anesthesia.     

Midazolam premedication reduces propofol requirements for sedation during regional anesthesia

PURPOSE: Propofol is often used for sedation during spinal anesthesia. We investigated the effects of midazolam premedication on the propofol requirements and incidence of complications during sedation. METHODS: In a prospective randomized, controlled, and single-blinded study, 50 patients undergoing elective gynecological surgery were randomly divided into control and midazolam groups. Patients in the midazolam group received 2 mg midazolam im 30 min before arrival at the operation room. After spinal anesthesia was instituted with intrathecal injection of hyperbaric tetracaine, we provided sedation using continuous infusion of propofol. The level of sedation was controlled at a level between "eyes closed but rousable to command" and "eyes closed but rousable to mild physical stimulation" by adjusting the infusion rate. During sedation, the propofol requirements and complications were recorded and patients were asked, two hours after the end of operation, whether they remembered intraoperative events. RESULTS: In the midazolam group, the loading dose, steady state infusion rate, and overall infusion rate of propofol were 0.74 mg x kg(-1), 2.86 mg x kg(-1) x hr(-1), and 3.32 mg x kg(-1) x hr(-1), respectively, which were about 17% lower than those in the control group (P<0.05). Moreover, midazolam premedication reduced the incidence of intraoperative memory (P < 0.05), but had no effects on other complications. CONCLUSION: Midazolam premedication reduced propofol requirements and the incidence of intraoperative memory during sedation. These effects on sedation using propofol during spinal anesthesia are considered beneficial for patients.     

颈内动脉输注异丙酚对胶质瘤切除术患者的脑保护作用

目的 探讨颈内动脉输注异丙酚对胶质瘤切除术患者的脑保护作用.方法 择期胶质瘤切除术患者40例和立体定向胶质瘤活检术患者20例,年龄40～64岁,体重48～73 kg.采用随机数字表法,将拟行胶质瘤切除术患者随机分为2组(n=20):颈内动脉给药组(IA组)和静脉给药组(Ⅳ组).拟行立体定向胶质瘤活检术患者为对照组(C组),采用2%利多卡因15～20 ml术野局部浸润麻醉.IA组和Ⅳ组采用异丙酚-瑞芬太尼-罗库溴铵行麻醉诱导.IA组麻醉诱导后行颈内动脉穿刺置管,颈内动脉靶控输注异丙酚.两组术中调整异丙酚和瑞芬太尼靶浓度,维持BIS值40～60.间断静脉注射罗库溴铵.术中取胶质瘤组织标本,采用免疫组化法测定胶质瘤组织水通道蛋白1(AQP1)和AQP4表达.于麻醉诱导前(T1)、切皮时(T2)、术毕时(T3)、拔除气管导管时(T4)记录MAP和HR;记录手术时间、麻醉用药情况.结果 与T1时比较,Ⅳ组T2,3时MAP和HR降低(P＜0.05),IA组各时点MAP和HR比较差异无统计学意义(P＞0.05).与IA组比较,Ⅳ组MAP和HR降低(P＜0.05).与C组比较,IA组和Ⅳ组AQP1和AQP4表达下调(P＜0.05).与Ⅳ组比较,IA组异丙酚用量减少(P＜0.05),AQP1和AQP4表达、瑞芬太尼和罗库溴铵用量、手术时间比较差异无统计学意义(P＞0.05).结论 与静脉输注异丙酚相比,颈内动脉途径给药不仅可减少胶质瘤切除术患者异丙酚的用量,而且对其脑保护作用没有影响.

Abstract：

Objective To investigate the cerebral protective effect of intracarotid infusion of propofol in patients undergoing resection of cerebral gliomas. Methods Sixty ASA Ⅰ- Ⅲ patients with cerebral glioma aged 40-64 yr weighing 48-73 kg were enrolled in this study. Forty patients undergoing resection of glioma under general anesthesia were randomly divided into 2 groups ( n = 20 each): intracarotid propofol group (group IA ) and intravenous propofol group (group Ⅳ). Twenty patients undergoing biopsy of glioma under local infiltration anesthesia with 2% lidocaine 15-20 md served as control group (group C). In IA and Ⅳ groups anesthesia was induced with TCI of propofol and remifentanil. Tracheal intubation was facilitated with rocuronium 0.6 mg/kg. The patients were mechanically ventilated. PErCO2 was maintained at 35-45 mm Hg. Anesthesia was maintained with TCI of propofol and remifentanil and intermittent iv boluses of rocuronium. In group IA internal carotid artery was cannulated after induction of anesthesia and propofol was administered by TCI via carotid artery while remifentanil was administered by TCI via peripheral vein. BIS was maintained at 40-60 during operation. ECG, MAP, HR, SpO2, PETCO2 and BIS were continuously monitored. MAP and HR were recorded before induction of anesthesia (T1) ,during skin incision (T2 ), at the end of operation (T3), during extubation ( T4 ). The glioma specimens were obtained for microscopic examination and determination of aquaporin 1 and aquaporin 4 ( AQP1, AQP4) expression by immunohistochemistry. Results MAP and HR were significantly decreased at T2 and T3 as compared with the baseline at T1 in group Ⅳ ( P ＜ 0.05), while there was no significant change in MAP and HR after induction of anesthesia in group IA ( P ＞ 0.05). The expression of AQP1 and AQP4 was down-regulated in IA and Ⅳ groups compared with group C (P ＜0.05). The propofol consumption during anesthesia was significantly less in group IA than in group Ⅳ (P ＜0.05). There was no significant diffe-rence in AQP1 and AQP4 expression, the amount of remifentanil and recuronium consumed and duration of operation betweenIA and Ⅳ groups ( P ＞ 0.05). Concltsion Intracarotid propofol can decrease the amount of propofol needed for maintenance of anesthesia as compared with intravenous administration and attenuate brain edema,indicating cerebral protective effect.     

Sevoflurane and isoflurane, but not propofol, decrease mivacurium requirements over time

PURPOSE: Volatile anesthetic agents potentiate neuromuscular blockade, but the magnitude of potentiation appears to be time dependent. The time course of this interaction was studied by measuring mivacurium infusion rates during sevoflurane, isoflurane and propofol anesthesia. METHODS: After informed consent, anesthesia was induced in 48 ASA physical status I-II adults with propofol, fentanyl and mivacurium 0.25 mg.kg(-1) and maintained with N(2)O (60%) and one of the three agents chosen at random: sevoflurane 1.9%; isoflurane 1.2%; or propofol 100-150 microgram.kg(-1).min(-1). Train-of-four stimulation was applied every 15 sec to the ulnar nerve. Neuromuscular blockade was monitored with accelerometry. At 5% recovery of the first twitch (T1), a mivacurium infusion was started and adjusted every five minutes to maintain 90-95% T1 depression. RESULTS: The time to 5% T1 recovery after the initial dose was similar in all groups (13-15 min). Fifteen minutes after the start of the infusion mivacurium requirements were greater (P < 0.05) in the propofol group (7.5 +/- 1.7 microgram.kg(-1).min(-1); mean +/- SD) than in either isoflurane (4.7 +/- 1.6 microgram.kg(-1).min(-1)) or sevoflurane (4.5 +/- 1.5 microgram.kg(-1).min(-1)) group. Then, the rate remained stable for propofol (6.2 +/- 1.4 microgram.kg(-1).min(-1) after 90 min of infusion) while it decreased with isoflurane to 2.9 +/- 1.6 microgram.kg(-1).min(-1) at 90 min (P < 0.05 vs propofol) and to 1.4 +/- 1.0 microgram.kg(-1).min(-1) in the sevoflurane group (P < 0.05 vs propofol and isoflurane). CONCLUSION: Sevoflurane and isoflurane do not prolong the effect of a bolus dose of mivacurium, but potentiation increases with time from 30-105 min of exposure. This interaction is greater with sevoflurane than isoflurane.     

Arterial baroreflex attenuation during and after continuous propofol infusion

The reduction of arterial blood pressure produced by propofol may be, in part, attributable to impaired baroreflex integrity. The purpose of this study was to investigate arterial baroreflex sensitivity during and after continuous propofol infusion. In urethane anaesthetized rabbits, left renal sympathetic nerves were exposed and placed on a bipolar silver electrode to record renal sympathetic nerve activity (RSNA). Mean arterial pressure (MAP) via a femoral artery and heart rate (HR) by electrocardiogram were continuously recorded. The rabbits were divided into two groups of eight each: Group 1, propofol 5 mg.kg-1 bolus followed by infusion 0.5 mg.kg-1 x min-1; Group 2, propofol 2 mg.kg-1 bolus followed by 0.2 mg.kg-1 x min-1. Phenylephrine pressor and sodium nitroprusside (SNP) depressor tests were carried out before propofol was started (control), at 15 and 30 min during 30 min infusion, and at 15, 30 and 60 min after its discontinuation. The change of RSNA was plotted with respect to every 5 mmHg increment and decrement of MAP to construct sympathetic baroreflex sigmoid curves, and to evaluate baroreflex sensitivity. The baroreflex sensitivity was also evaluated by calculating the ratio of maximum increase of RSNA or HR to SNP-induced maximum decrease of MAP (delta RSNA/delta MAP, delta HR/delta MAP). Despite the same decreases or increases in MAP, RSNA was attenuated after 15 and 30 min of propofol infusion in both groups compared with control (P < 0.05). Decreased delta RSNA/delta MAP gradually returned to the control level 60 min after discontinuation of propofol in Group 1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of sevoflurane and propofol on neuromuscular blocking action of Org 9426 (rocuronium bromide) infused continuously in Japanese patients

BACKGROUND: The purpose of this study was to investigate the interaction of anesthetic agents with Org 9426 (rocuronium bromide) infused continuously. The effect of intubation dose of Org 9426 on its infusion rate was also investigated. METHODS: Total of 38 Japanese patients were randomly allocated either to receive intubation dose of 0.6 or 0.9 mg x kg(-1) of Org 9426. These patient groups were anesthetized with either sevoflurane or propofol. Infusion of Org 9426 was started with the initial infusion rate of 7 microg x kg(-1) x min(-1) when T1 reappeared after the intubation dose. The infusion rate was adjusted to keep the height of T1 between 3-10% of the control value. RESULTS: The rates of infusion 90 min after the start of infusion were 3.4, 7.5, 3.9 and 7.7 microg x kg(-1) x min(-1) for the 0.6 mg x kg(-1)-sevoflurane, 0.6 mg x kg(-1) propofol, 0.9 mg x kg(-1)-sevoflurane and 0.9 mg x kg(-1) propofol groups, respectively. Sevoflurane significantly reduced the infusion rate with both intubation doses. The mean infusion rates of 0.9 mg x kg(-1) groups were slower than those of 0.6 mg x kg(-1) groups up to 60 min after the start of infusion. Mean clearance of Org 9426 during infusion was not different between sevoflurane and propofol anesthesia. CONCLUSIONS: Patients receiving sevoflurane anesthesia required a markedly lower Org9426 infusion rate compared with patients receiving propofol anesthesia.     

Dose requirements of pentazocine during abdominal surgery in total intravenous anesthesia using propofol

BACKGROUND: To determine the dose requirements of pentazocine when administered as a single bolus dose in total intravenous anesthesia with propofol for abdominal surgery. METHODS : One hundred and fifty-six patients scheduled for abdominal surgery were analyzed retrospectively. Patients were classified into three groups according to duration of the operation ; under 120 min (Group 1, n=87) ; 120-240 min (Group 2, n=56) ; over 240 min (Group 3, n=13). Anesthesia was induced with propofol using target controlled infusion method, and was maintained with propofol infusion, pentazocine as a single dose before incision, and intermittent administration of vecuronium with 40% oxygen in air. RESULTS: Dosage of pentazocine was significantly increased according to length of the operation. The maintenance doses of propofol were not different among the three groups. Awakening time in about 80% of patients in each group was within 15 minutes. There are no severe complications. CONCLUSIONS : Total intravenous anesthesia with propofol and pentazocine is useful to stabilize hemodynamics and to achieve rapid recovery. For the operation within 120 min, 0.7 mg x kg(-1) of pentazocine is necessary whereas 0.8 mg x kg(-1) of pentazocine is needed in the operation of 120-240 min.     

Response of human growth hormone to anesthesia induction with propofol

Although there are distinct differences in both pharmacokinetics and chemical structure, propofol has sedative effects similar to those of benzodiazepines. Both diazepam and thiopental, commonly used agents for inducing anaesthesia, show some typical neuroendocrine effects such as liberation of human growth hormone (hGH) in addition to their well-known influences on the cardiovascular system. It was our aim to examine the endocrine response of hGH after induction of anaesthesia with propofol and to compare any possible effects with those of diazepam and thiopental. The study was performed on 30 non-premedicated patients, who underwent plastic-surgery (mean age: x = 35 +/- 8.3 years, mean body weight: x = 68.9 +/- 23.2 kg). No signs of endocrine disturbances were found in the patients prior to the study. Patients were divided in a random fashion into 3 groups of 10 persons each: In group 1 propofol was given in a bolus injection (2 mg/kg) and then by infusion for a period of 10 min (0.2 mg/kg/min). In group 2 diazepam (0.3 mg/kg) and in group 3 thiopental (5 mg/kg) were administered as a bolus to induce anesthesia. All patients were intubated immediately after induction of anesthesia and then relaxed using vecuronium (1 mg/kg). Ventilation was performed mechanically during the entire operative period (N2O/O2 - FiO2:0.33, tidal volume 10 ml/kg, respiratory rate: 14/min). To maintain anesthesia halothane (0.5-1.0 vol.-%) and meperidine (0.75 mg/kg) were added 15 min after induction.(ABSTRACT TRUNCATED AT 250 WORDS)     

Spectral entropy and bispectral index as measures of the electroencephalographic effects of propofol

Recently, Datex-Ohmeda introduced the Entropy Moduletrade mark for measuring depth of anesthesia. Based on the Shannon entropy of the electroencephalogram, state entropy (SE) and response entropy (RE) are computed. We investigated the dose-response relationship of SE and RE during propofol anesthesia in comparison with the Bispectral Indextrade mark (BIS). Twenty patients were studied without surgical stimulus. Anesthesia was induced by a constant propofol infusion of 2000 mg/h (451 +/- 77 microg x min(-1) x kg(-1)) via a large forearm vein. Propofol was infused until substantial burst suppression occurred (more than 50%) or mean arterial blood pressure decreased to <60 mm Hg. Hereafter, infusions were stopped until recovery of BIS values up to 60 was reached. Subsequently, the constant propofol infusion of 2000 mg/h was restarted to increase depth of anesthesia and again decreased (infusion was stopped) within the BIS value range of 40-60. The coefficient of determination (R2) and the prediction probability (P(K)) were calculated to evaluate the performance of SE, RE, and BIS to predict changing propofol effect-site concentrations. R2 values for SE, RE, and BIS of 0.88 +/- 0.08, 0.89 +/- 0.07, and 0.92 +/- 0.06, respectively, were similar. The calculated P(K) values, however, revealed a significant difference between SE and RE compared with BIS, with P(K) = 0.77 +/- 0.09, 0.76 +/- 0.10, and 0.84 +/- 0.06, respectively. BIS seems to show slight advantages in predicting propofol effect-site concentrations compared with SE and RE, as measured by P(K) but not as measured by R2.