Intraoperative awareness during propofol anesthesia with epidural anesthesia

This report describes a case of awareness and recall during propofol anesthesia combined with epidural anesthesia in a 32-year-old woman scheduled for a resection of left ovarian tumor. After induction, anesthesia was maintained with propofol and epidural anesthesia. About one hour into maintenance, the patient was moving with haemodynamic signs suggesting inadequate analgesia. Immediately after extubation, the patient could recall the abdomen being touched during laparotomy. This case indicates that even if appropriate dose of propofol is administrated, intraoperative awareness may occur especially with inadequate analgesia.     

A dopamine infusion decreases propofol concentration during epidural blockade under general anesthesia

PURPOSE: It is common clinical practice to use dopamine to manage the reduction in blood pressure accompanying epidural blockade. As propofol is a high-clearance drug, propofol concentrations can be influenced by cardiac output (CO). The purpose of the present study was to investigate the effects of dopamine infusions on propofol concentrations administered by a target-controlled infusion system during epidural block under general anesthesia. METHODS: 12 patients undergoing abdominal surgery were enrolled in this study. Anesthesia was induced with propofol and vecuronium 0.1 mg.kg(-1), and maintained using 67% nitrous oxide, sevoflurane in oxygen and constant infusion of propofol. Propofol was administered to all subjects via target-controlled infusion to achieve a propofol concentration at 6.0 microg.mL(-1) at intubation and 2.0 microg.mL(-1) after intubation. Before and after the administration of 10 mL of 1.5% mepivacaine from the epidural catheter and dopamine infusion at 5 microg.kg(-1).min(-1), CO and effective liver blood flow (LBF) were measured using indocyanine green. Blood propofol concentration was also determined using high-performance liquid chromatography. RESULTS: At one hour after epidural block and dopamine infusion, CO was significantly increased from 4.30 +/- 1.07 L.min(-1) to 5.82 +/- 0.98 L.min(-1) (P < 0.0001), and effective LBF was increased 0.75 +/- 0.17 L.min(-1) to 0.96 +/- 0.18 L.min(-1) (P < 0.0001). Propofol concentration was significantly decreased from 2.13 +/- 0.24 microg.mL(-1) to 1.59 +/- 0.29 microg.mL(-1) (P < 0.0001). CONCLUSIONS: Propofol concentrations decrease with an increase in CO, suggesting the possibility of inadequate anesthetic depth following catecholamine infusion during propofol anesthesia.     

Which vasopressor should be used to treat hypotension during magnesium sulfate infusion and epidural anesthesia?

Ephedrine restores and/or protects uterine blood flow and fetal well-being in laboratory animals. In contrast, alpha 1-adrenergic agonists worsen uterine blood flow and fetal condition. We previously demonstrated that magnesium sulfate (MgSO4) attenuates the detrimental effects of phenylephrine on uterine vascular resistance in gravid ewes. Therefore, we performed this study to determine whether ephedrine or phenylephrine better restores and protects uterine blood flow and fetal oxygenation during epidural anesthesia-induced hypotension in hypermagnesemic gravid ewes. Twelve chronically instrumented gravid ewes were each used for three experiments: 1) ephedrine, 2) phenylephrine, and 3) normal saline (NS)-control. For each experiment the protocol was as follows: 1) at time zero, intravenous infusion of MgSO4 was begun; 2) at 150 min a thoracic level of epidural anesthesia was achieved with 2% lidocaine; and 3) at 165 min, an intravenous infusion of ephedrine, phenylephrine, or NS was begun and continued through 195 min. Epidural anesthesia uniformly decreased maternal mean arterial blood pressure (MAP), heart rate, cardiac output, uterine blood flow, and fetal PO2 in each of the three groups. Both ephedrine and phenylephrine restored maternal MAP to baseline, as expected from the experimental design. Ephedrine significantly increased cardiac output and uterine blood flow when compared with NS-control, but phenylephrine did not. Phenylephrine significantly increased uterine vascular resistance when compared with NS-control, but ephedrine did not. As a result, fetal pH and PO2 were significantly greater during ephedrine infusion than during infusion of NS-control. Fetal pH was stable during ephedrine infusion, but it continued to decrease during phenylephrine infusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Frequency of hypotension and bradycardia during general anesthesia, epidural anesthesia, or integrated epidural-general anesthesia for total hip replacement

STUDY OBJECTIVE: To evaluate the frequency of hypotension and bradycardia during integrated epidural-general anesthesia as compared with general anesthesia or epidural anesthesia alone. DESIGN: Prospective, randomized, open, multicenter study. SETTING: Inpatient anesthesia at 7 University or Hospital Departments of anesthesia. PATIENTS: 210 ASA physical status I, II, and III patients undergoing elective total hip replacement. INTERVENTIONS: Using a balanced randomization method, each hospital enrolled 30 consecutive patients who received integrated epidural-general anesthesia, epidural anesthesia, or general anesthesia. MEASUREMENTS AND MAIN RESULTS: Occurrence of clinically relevant hypotension (systolic arterial blood pressure (BP) decrease >30% from baseline), or bradycardia (heart rate (HR) <45 bpm) requiring pharmacologic treatment were recorded, as well as routine cardiovascular parameters. Clinically relevant hypotension during induction of nerve block was reported in 13 patients receiving epidural block (18%) and 16 patients receiving epidural-general anesthesia (22%) (p = 0.67). Subsequently, 22 of the remaining 54 patients in the epidural-general anesthesia group (41%) developed hypotension after the induction of general anesthesia, as compared with 16 patients of the general anesthesia group (23%) (p = 0.049). No differences in HR or in frequency of bradycardia were observed in the three groups. CONCLUSIONS: The induction of general anesthesia in patients with an epidural block up to T10 increased the odds of developing clinically relevant hypotension as compared with those patients who received no epidural block, and was associated with a twofold increase of the odds of hypotension as compared with the use of epidural anesthesia alone.     

Ephedrine,but not phenylephrine,increases bispectral index values during combined general and epidural anesthesia

Ephedrine and phenylephrine are used to treat hypotension during combined general and epidural anesthesia, and they may change anesthetic depth. In the current study, we evaluated the effects of ephedrine versus phenylephrine on bispectral index (BIS) during combined general and epidural anesthesia. After injection of ropivacaine through the epidural catheter, general anesthesia was induced with propofol and vecuronium, and was maintained with 0.75% sevoflurane. Approximately 10 min after the intubation, BIS was recorded as a baseline value. Patients with decreases in arterial blood pressure <30% of the preanesthetic values were defined as control group (n = 9). Patients who had to be treated for larger decreases in arterial blood pressure were randomly assigned to receive ephedrine 0.1 mg/kg (n = 17) or phenylephrine 2 micro g/kg (n = 17). BIS values were recorded at 1-min intervals for 10 min. BIS in the ephedrine group was significantly larger from 7 to 10 min than that in the control and phenylephrine groups (P < 0.05). Seven patients in the ephedrine group had BIS >60, whereas no patient in the control and phenylephrine groups had BIS >60 (P < 0.005). Ephedrine, but not phenylephrine, increased BIS during general anesthesia combined with epidural anesthesia.     

Transient maternal hypotension following epidural anesthesia

Transient maternal hypotension following regional anesthesia can lead to significantly lower umbilical cord pH values. Although this acidosis has not been found to be clinically significant, acidosis may increase the placental transfer of local anesthetic agents as a result of "ion trapping." The purpose of this study was to examine the pharmacologic and clinical consequences of transient maternal hypotension following epidural anesthesia with 0.5% bupivacaine before cesarean section. Patients were divided into two groups based on the development of maternal hypotension, defined as a systolic blood pressure less than 100 torr or a decrease of 30% or more from the preanesthetic level. Thirteen patients (33%) developed hypotension that was corrected within 2.1 +/- 1.8 min. The pH of umbilical cord venous and arterial blood and the concentration of bupivacaine were significantly lower (P less than 0.05) in neonates of mothers in the hypotensive group than in neonates of mothers that did not develop hypotension. The results show, however, that transient maternal hypotension following epidural anesthesia does not lead to a greater placental transfer of bupivacaine due to "ion trapping" even though neonatal cord blood pH decreases.     

硬膜外麻醉下靶控输注丙泊酚镇静对血液动力学的影响

目的 观察靶控输注（TCI）丙泊酚镇静对硬膜外麻醉患者血液动力学的影响,并确定血压降低50％的靶控浓度。方法 28例择期行硬膜外麻醉手术的患者,ASA Ⅰ～Ⅱ级,年龄17～67岁,术中采用丙泊酚TCI镇静,靶控浓度从0．4μg／ml开始,以0．4μg／ml梯度逐渐上升,直至患者入睡并维持该浓度直至手术结束。麻醉中观察并记录SBP、DBP、MAP、HR和SpO2的变化。结果 MAP和HR随靶控浓度的升高而降低,降低的平均幅度分别为23％和11％。MAP降低50％的靶控浓度为6．31μg／ml。结论 硬膜外麻醉下丙泊酚TCI镇静时,达意识消失状态时的靶控浓度远低于EC50,镇静深度易于调控,血液动力学较稳定。     

Comparison of renal function under deliberate hypotension during epidural plus light-enflurane anesthesia and during enflurane anesthesia

We compared the effects of deliberate hypotension induced with trimethaphan on renal function and renal tubular damage under combined epidural and light-enflurane anesthesia (epidural group) and enflurane anesthesia alone (enflurane group). The mean arterial blood pressure was maintained at 50–55 mm Hg for 2.5 h in both groups using continuous infusion of trimethaphan. The urine volume and free water clearance were significantly greater in the epidural group than in the enflurane group [1.8±1.8 (SD)vs 0.4±0.3 ml·kg⁻¹·h⁻¹ and 0.81±1.30vs −0.15±0.22 ml·min⁻¹, respectively] (P<0.05). The creatinine clearance and fractional sodium excretion rate did not differ significantly between the two groups. Urinary excretion of norepinephrine was significantly less in the epidural group than in the enflurane group (P<0.05); however, epinephrine excretion did not differ. Urinary excretion ofN-acetyl-β-d-glucosaminidase was significantly less in the epidural group than in the enflurane, group (4.2±2.5vs 12.2±4.6 U·g⁻¹ CR) (P<0.01). The plasma antidiuretic hormone concentration was significantly lower in the epidural group compared to the enflurene group (13±23vs 57±42 pg·ml⁻¹) (P<0.05). No significant difference in plasma atrial natriuretic peptide concentration was found between the groups. We conclude that renal function during trimethaphan-induced hypotension is better maintained under epidural plus light-enflurane anesthesia than under enflurane anesthesia alone.     

Neostigmine antagonism of rocuronium block during anesthesia with sevoflurance, isoflurane or propofol

PURPOSE: To examine the influence of continuing administration of sevoflurane or isoflurane during reversal of rocuronium induced neuromuscular block with neostigmine. METHODS: One hundred and twenty patients, divided into three equal groups, were randomly allocated to maintenance of anesthesia with sevoflurane, isoflurane or propofol. Neuromuscular block was induced with rocuronium and monitored using train-of-four (TOF) stimulation of the ulnar nerve and recording the force of contraction of the adductor pollicis muscle. Neostigmine was administered when the first response in TOF had recovered to 25%. At this time the volatile agent administration was stopped or propofol dosage reduced in half the patients in each group (n = 20 in each group). The times to attain TOF ratio of 0.8, and the number of patients attaining this end point within 15 min were recorded. RESULTS: The times (mean +/- SD) to recovery of the TOF ratio to 0.8 were 12.0 +/- 5.5 and 6.8 +/- 2.3 min in the sevoflurane continued and sevoflurane stopped groups, 9.0 +/- 8.3 and 5.5 +/- 3.0 min in the isoflurane continued and isoflurane stopped groups, and 5.2 +/- 2.8 and 4.7 +/- 1.5 min in the propofol continued and propofol stopped groups (P < 0.5-01). Only 9 and 15 patients in the sevoflurane and isoflurane continued groups respectively had attained a TOF ratio of 0.8 within 15 min (P < 0.001 for sevoflurane). CONCLUSIONS: The continued administration of sevoflurane, and to a smaller extent isoflurane, results in delay in attaining adequate antagonism of rocuronium induced neuromuscular block.     

异丙酚病人自控镇静与靶控镇静的对比研究

目的 比较异丙酚病人自控镇静术（PCS）与靶控镇静术（TCI）在硬膜外麻醉中的应用价值。方法 32例行下肢或下腹部手术的成年患者,硬膜外麻醉满意后,随机分成两组,PCS组行病人自控镇静,单次剂量0.3mg/kg,锁定时间2min;TCI组行靶控输注,术中维持镇静深度于OAA/S镇静评分3分。监测不同时点的镇静评分、双频谱指数（BIS）、边缘频率（95％SEF）、异丙酚靶浓度（CP）及血药浓度（Cm）、术中遗忘及镇静满意程度,并比较BIS、95％SEF及Cm与镇静评分的相关性。结果 所有患者均对镇静效果满意,PCS组镇静深度较浅,异丙酚用药量较TCI组少（分别为 2.5mg·kg-1·h-1与 3.8mg·kg-1·h-1,P<0.01）,且个体差异明显。TCI组血药浓度平稳,并与靶浓度基本相符,术中及术后遗忘率较自控镇静组高（分别为31％与69％,P<0.01）。BIS与镇静评分的相关性（γ=0.73）较95％SEF及Cm高。结论 两种方法镇静效果均满意,但又各具特点。自控镇静体现了个体化给药原则,用药量较少,其合理的设置至关重要。靶控镇静的深度平稳且易于调控,遗忘良好,但由于其治疗窗较窄,需要有良好的监测。BIS是监测硬膜外麻醉中镇静深度的较敏感指标。     

脑状态指数在七氟醚或丙泊酚诱导时的变化

目的 观察七氟醚或丙泊酚麻醉时脑状态指数(CSI)的变化.方法 30例腹腔镜手术患者随机均分成七氟醚组(S组)和丙泊酚组(P组).麻醉诱导:S组吸入2%的七氟醚,每隔1分钟增加1%;P组每隔1分钟重复给予15 mg丙泊酚,直至患者意识消失.记录患者诱导期的CSI数值,并对患者的镇静程度采用警觉/镇静评分(OAA/S)标准评分.结果 S组与P组术前CSI基础值差异无统计学意义,随着麻醉的加深,两组的CSI数值均明显下降(P<0.01),至OAA/S 1分时S组与P组的CSI数值较OAA/S 5分时明显下降(P<0.05或P<0.01),S组与P组的CSI与OAA/S的相关系数r分别为0.843和0.812.结论 CSI监测可反映七氟醚或丙泊酚麻醉时的麻醉深度.     

A case of coronary artery spasm during epidural anesthesia with continuous infusion of propofol

A 50-year-old male patient was scheduled for left partial pulmonary resection and biopsy. The patient had neither complication nor history of ischemic heart disease. After arriving in the operation room, an epidural catheter was inserted into the epidural space at the T 4-5 intervertebral space. Anesthesia was induced with intravenous propofol 100 mg, fentanyl 100 microgram and vecuronium 6 mg and then a double lumen endotracheal tube was inserted. Anesthesia was maintained with O2 and air (FIO2 0.3-1.0), continuous infusion of propofol, intermittent intravenous administration of fentanyl and epidural injection of 1% lidocaine. Forty-five minutes after the start of operation, ECG showed an elevation of ST segment and soon it passed into ventricular tachycardia and ventricular fibrillation. The patient was treated with cardiopulmonary resuscitation. Fifteen minutes later, ECG returned to sinus rhythm but the elevation of ST segment remained. We considered that these cardiac events were due to coronary spasm, and started continuous infusion of nitroglycerin and nicorandil. One hour later, ST segment returned to normal. The possible inducing factors in this case were altered balance between sympathetic and parasympathetic nervous activity caused by infusion of propofol and epidural block, and alpha-stimulation caused by ephedrine.     

异丙酚和异氟醚麻醉对硝普钠控制性降压的影响

目的评价异丙酚麻醉对硝普钠控制性降压的影响.方法16例显微神经外科手术患者随机分成两组,待硬脑膜打开后,Ⅰ组(n=8)以100μg@kg-1@min-1异丙酚静滴维持麻醉;Ⅱ组(n=8)以吸入1.3MAC异氟醚维持麻醉.以0.01%硝普钠溶液使MAP降低40%.结果Ⅰ组血压易于下降和维持,停止降压后Ⅰ组MAP显著低于Ⅱ组(P＜0.05);Ⅰ组硝普钠平均剂量显著低于Ⅱ组(P＜0.001),硝普钠总量较Ⅱ组减少53%;两组各时点HR,血浆去甲肾上腺素浓度及尿量无显著性差异;维持降压期间Ⅰ组血浆肾上腺素浓度(PE)显著低于Ⅱ组(P＜0.05).结论异丙酚维持麻醉可增强硝普钠控制性降压效果,减少并发症发生.其机制可能与异丙酚的直接扩血管和交感抑制作用有关.