A comparison of intra-articular magnesium and/or morphine with bupivacaine for postoperative analgesia after arthroscopic knee surgery

Purpose

Both magnesium and morphine provide enhanced patient analgesia after arthroscopic knee surgery when administered separately via the intra-articular route. Magnesium sulfate amplifies the analgesic effect of morphine. This study was designed to compare the analgesic effects of intra-articular magnesium and morphine, with bupivacaine, when used separately and in combination.

Methods

Eighty patients undergoing arthroscopic menisectomy were randomized blindly into four intra-articular groups: group B+Mor+Mg received 20 ml 0.25% bupivacaine, morphine 2 mg, and magnesium 150 mg; group B+Mor received 20 ml 0.25% bupivacaine and morphine 2 mg; group B+Mg received 20 ml 0.25% bupivacaine and magnesium 150 mg; and group B received 20 ml 0.25% bupivacaine. Pain scores at rest and during movement, analgesic duration, and total analgesic consumption were recorded.

Results

Group B+Mor and group B+Mg patients had equally effective postoperative analgesia. Group B+Mor+Mg patients had significantly reduced visual analogue scale (VAS) values both at rest and during movement and significantly increased time to first postoperative analgesic request, as well as significantly reduced total analgesic consumption, compared with the other groups.

Conclusion

Intra-articular administration of magnesium sulfate or morphine, with bupivacaine, had comparable analgesic effects in the doses used. Their combination provided more effective postoperative analgesia than either drug alone.     

Influence of bupivacaine as an adjuvant to epidural morphine for analgesia after cesarean section

The effect of the addition of bupivacaine to epidural morphine (EM) on postoperative analgesia was evaluated in 150 patients after cesarean section performed under epidural anesthesia with carbonated lidocaine. Fifty patients received 3 mg EM without bupivacaine, 50 received 3 mg EM with 0.125% bupivacaine, 25 received 5 mg EM without bupivacaine, and 25 patients received 5 mg EM with 0.125% bupivacaine. Patients were assessed for quality and duration of postoperative analgesia, as well as the incidence and severity of side effects. The addition of bupivacaine did not affect the quality or duration of analgesia afforded by EM and did not influence the incidence or severity of side effects. Furthermore, there was no statistically significant difference in the analgesia obtained by patients receiving 3- and 5-mg doses of EM with or without bupivacaine.     

Pre-emptive analgesia with epidural morphine or morphine and bupivacaine

Studies of preemptive analgesia in humans have shown conflicting results. The study design, patient population and the duration of assessment of postoperative pain are important in the evaluation of preemptive analgesia. We carried out a prospective, randomized, double-blind controlled study in 80 patients of physical status ASA 1-3 undergoing upper abdominal and thoracic surgery. Patients received two epidural injections, one 20 minutes before induction and the other at the end of surgery. Study solution was either morphine (50 micrograms/kg), with or without 0.1% bupivacaine in 10 ml of normal saline, or normal saline alone. The study groups (Pre M, Pre MB) were given either morphine or morphine-bupivacaine before induction and saline at the end of surgery. The control groups (Post M, Post MB) were given saline before induction and morphine or morphine-bupivacaine at the end of surgery. Postoperative pain was assessed with a Visual Analogue Scale (VAS) during coughing and deep breathing at six-hourly intervals for five days. Epidural morphine was given if the VAS exceeded 4. Pre MB compared to Post MB had a significantly increased interval between the analgesic top-ups (P < 0.01) and decreased total postoperative morphine requirements (P < 0.0001) and number of top-ups (P < 0.001). Pre M and Post M were comparable. Pre MB compared to Pre M had significantly decreased total postoperative morphine requirements (P < 0.0001) and number of top-ups (P < 0.0001). Epidural morphine plus bupivacaine is effective as a preemptive analgesic. Morphine plus bupivacaine has better efficacy than morphine given alone before the induction of anaesthesia.     

Continuous epidural infusion of bupivacaine and morphine for postoperative analgesia after hysterectomy

The analgesic efficacy and side-effects of combined epidural infusion of bupivacaine and morphine, in comparison with these drugs alone, for postoperative analgesia after hysterectomy (60 patients) were evaluated. Before general anaesthesia, all patients had an epidural catheter placed (Th11-12) and 20 ml of 0.5%, bupivacaine was injected. In random order, epidural infusion was continued for 24 h with either 0.25% bupivacaine 4 ml.h-1 (BUPI-group), a bolus of 2 mg of morphine followed by morphine 0.2 mg.h-1 (MO-group), or a combination of the two drugs (COMB-group). A urinary bladder catheter was kept for 24 h. Supplementary postoperative pain medications were i.m. morphine 0.1 mg.kg-1 or rectal indomethacin 50 mg, on request. Immediately after awakening from general anaesthesia and transfer to the recovery room, 18/20 of the BUPI-group patients, 17/20 of the MO-group patients and 19/20 of the COMB-group patients were pain-free. In the postoperative evening and the first postoperative morning, the corresponding figures were 7/20 and 10/20 in the BUPI-group, 15/20 and 15/20 in the MO-group, and 18/20 and 15/20 in the COMB-group (postop, evening; P less than 0.01 BUPI vs. others). The number of patients requiring supplementary analgesics (morphine and indomethacin during the first 24 h was greatest in the BUPI-group P less than 0.01). The number of patients who vomited during the 24-h period was 3 in the BUPI-group, 9 in the MO-group and 5 in the COMB-group.(ABSTRACT TRUNCATED AT 250 WORDS)     

A comparison of epidural tramadol and epidural morphine for postoperative analgesia

The present study compared epidural tramadol with epidural morphine for postoperative analgesia in 20 patients undergoing major abdominal surgery. Intraoperatively, the patients were anaesthetized by a balanced technique of general anaesthesia combined with lumbar epidural lidocaine. In ten of the patients 100 mg tramadol diluted in 10 ml normal saline was also injected epidurally, while 4 mg epidural morphine was used in the other ten patients. In all patients, the visual analogue pain score, PaO₂, PaCO₂ and respiratory rate were monitored every hour for the first 24 hr postoperatively. In both the tramadol and morphine groups, the mean hourly pain scores ranged from 0.2 ± 0.6 to 1.4 ± 2.5 throughout the period of observations. However, the mean PaO₂ was decreased postoperatively in the epidural morphine group, while no change was observed in the epidural tramadol group. The maximal decrease of PaO₂ in the epidural morphine group was observed at the tenth hour postoperatively, when it decreased to 72.8 ± 10.3 mm Hg. This was not associated with any increase in PaCO₂ or a decrease of respiratory rate, suggesting that hypoxaemia rather than hypercarbia or decreased respiratory rate may be an earlier indicator of respiratory depression in patients breathing room air without oxygen supplementation. The absence of clinically relevant respiratory depression following epidural tramadol compared with epidural morphine may be attributed to the different mechanisms of their analgesic action. The results suggest that epidural tramadol can be used to provide prolonged postoperative analgesia without serious side effects.     

剖宫产术后患者左旋布比卡因、罗哌卡因与布比卡因混合芬太尼硬膜外镇痛的效应

目的 比较左旋布比卡因、罗哌卡因和布比卡因复合芬太尼用于剖宫产术后硬膜外镇痛的效果和副作用。方法 采用随机双盲法,将51例择期行剖宫产术的足月、单胎孕妇分为三组:左旋布比卡因组(L组)、罗哌卡因组(R组)和布比卡因组(B组),每组17例。术后分别采用0.125％左旋布比卡因、0.2％罗哌卡因及0.125％布比卡因复合小剂量芬太尼(2μg·ml-1)行病人自控硬膜外镇痛(PCEA)。观察各组术后48 h内镇痛效果、运动阻滞程度变化以及恶心呕吐、尿潴留等副作用的发生率。结果 三组产妇术后视觉模拟评分、改良Bromage评分比较差异均无显著性(P>0.05)。三组产妇对PCEA的非常满意率差异无显著性(L组88.2％,R组76.5％,B组81.3％,P>0.05)。三组不良反应发生率及排气时间差异无显著性(P>0.05)。结论 0.125％左旋布比卡因混合芬太尼(2μg·ml-1)用于产科术后硬膜外镇痛可获得满意的镇痛效果且无明显毒副作用。     

A comparison between post-operative analgesia after intrathecal nalbuphine with bupivacaine and intrathecal fentanyl with bupivacaine after cesarean section

BackgroundAdding intrathecal opioids to intrathecal local anesthetics to decrease their doses and provide hemodynamic stability are major goals during spinal anesthesia in cesarean section. Different opioids were used to select the one with the longest duration of analgesia and the least side effects. In this study, intrathecal nalbuphine was compared with intrathecal fentanyl as an adjuvant to hyperbaric bupivacaine in cesarean section.Patients and methodsSixty female patients of ASA grades I and II presented for elective cesarean deliveries with spinal anesthesia were randomly allocated to 2 equal groups; Group F: 30 patients received intrathecal injection of 2 ml of 0.5% hyperbaric bupivacaine plus 0.5 ml fentanyl (25 μg); Group N: 30 patients received intrathecal injection of 2 ml of 0.5% hyperbaric bupivacaine plus 0.5 ml nalbuphine (0.8 mg). The onset of sensory and complete motor blockade, time of sensory blockade, duration of analgesia and motor blockade, fetal Apgar score, visual analog scale score, oxygen saturation, adverse effects and hemodynamic parameters were recorded intra-operatively and up to 4 h post-operatively. The effective analgesic time was recorded.ResultsThe onset of complete motor block was significantly more rapid in fentanyl group than in nalbuphine group. The duration of post-operative analgesia was more prolonged in nalbuphine group but the difference was insignificant. No significant difference was found between both groups as regards the duration of sensory block, motor block, duration of analgesia, fetal Apgar score, visual analog scale score, hemodynamic parameters and oxygen saturation. Adverse effects were less common in nalbuphine group but the difference was insignificant.ConclusionEither intrathecal nalbuphine 0.8 mg or intrathecal fentanyl 25 μg combined with 10 mg bupivacaine provides good intra-operative and early post-operative analgesia in cesarean section.     

Optimal dose of fentanyl for postoperative epidural analgesia after cesarean section

BACKGROUND: The aim of this study was to investigate which dose of fentanyl in ropivacaine for epidural anesthesia will provide effective analgesia with minimal side effects after cesarean section (CS). METHODS: Fifty eight patients scheduled for CS were randomly allocated to two groups according to fentanyl dose in epidural analgesia: group F1 (11 microg x hr(-1); n=30) or group F 2 (21 microg x hr(-1); n= 28). Ropivacaine 0.2% 100 ml with fentanyl 400 or 800 microg was administered into the epidural space in the groups F1 and F 2, respectively. Pain scores (visual analogue scale: VAS) with cough or movement, Bromage score, incidence of diclofenac or pentazocine administration, satisfaction score (VAS) and side effects (nausea, vomiting and pruritus) were recorded after CS. RESULTS: Pain scores with cough or movement were significantly lower in the group F 2 than the group F 1 at twelve and twenty-four hours after CS. Bromage score at twelve hours was lower in the group F 2 than the group F 1. The incidences of side effects were similar between the two groups. Satisfaction score was significantly higher in the group F 2 than the group F 1. CONCLUSIONS: We conclude that continuous epidural administration of fentanyl 21 microg x hr(-1) with ropivacaine provides the optimum balance between pain relief and side effects compared with fentanyl 11 microg x hr(-1) with ropivacaine after CS.     

硬膜外负荷量吗啡加芬太尼应用于剖宫产术后镇痛的观察

目的观察预充负荷量吗啡和芬太尼复合液对吗啡术后镇痛的影响。方法选择剖宫产手术80例,年龄23～34岁,ASAⅠ～Ⅱ级,无心、肺、肾及神经系统疾病,无长期服用镇痛药和镇静药病史,均采用硬腰联合麻醉,根据负荷量的不同随机分为吗啡组(M组)和吗啡+芬太尼组(F+M组),负荷量配方:M组吗啡2mg+昂丹司琼4mg稀释到5mL,F+M组吗啡1mg+芬太尼0.1mg+昂丹司琼4mg稀释到5mL。采用视觉模式评分法评估产妇镇痛效果,观察2组患者不良反应。结果 M组与F+M组VAS评分在1h和2h差异有统计学意义(P(0.01,P(0.05),4h、8h、12h2组患者VAS评分差异无统计学意义(P(0.05)。2组患者均无呼吸抑制,恶心、呕吐和瘙痒发生率差异均无统计学意义(P(0.05)。结论在负荷量中吗啡和芬太尼联合使用既能够明显增强术后早期镇痛作用,又不会明显增加稍后镇痛泵中吗啡持续应用所产生的不良反应,值得推广应用。     

单次剂量吗啡复合罗比卡因用于剖宫产术后PCEA的效果评价

目的 用单次剂量吗啡复合持续剂量不同浓度罗比卡因应用于剖宫产术后硬膜外自控镇痛（patient controlled epidural analgesia,PCEA)，与持续剂量吗啡和罗比卡因相比较，寻求一种减少吗啡用量，更适合下腹部手术的硬膜外自控镇痛方法。方法 80例ASAⅠ-Ⅱ级行子宫下段剖宫产的产妇，随机分为四组，单次剂量吗啡分三组；SMR0.1组，0.1%罗比卡因；SMR0.2组，0.2%罗比卡因，SMR0.05组，0.05%罗比卡因，三组均先单次静注吗啡1mg 氟哌利多持续硬膜外给药，观察产妇24小时内VAS，镇静评分，Prine Henry评分，改良Bromage分级的变化，PONV等不良反应的发生率，记录产妇24小时内用药量。结果 VAS评分；CM组，SMR0.2组大于SMR0.1组，SM0.05组和CM组。SMR0.1组，SMR0.05组尿潴留，排气时间延长发生率明显低于SMR0.2组，CM组，结论 1mg吗啡单次给药复合维持剂量0.1%罗比卡因用于剖宫产术后PCEA能够取得良好的镇痛效果。感觉-运动阻滞分离效果好，不良反应少。     

Focus on mobilisation after lower abdominal surgery. A double-blind randomised comparison of epidural bupivacaine with morphine vs. lidocaine with morphine for postoperative analgesia

BACKGROUND: Epidural infusion of morphine, usually with bupivacaine, for postoperative pain relief has proved to be safe and effective. Lidocaine with its short duration of action and low toxicity may be an alternative to bupivacaine. The clinical importance of the choice of local anaesthetic drug on mobilisation after lower abdominal surgery has not been studied previously. METHODS: A total of 52 patients was randomised to epidural infusion of morphine (1.6-4.4 micrograms.kg-1.h-1) with either lidocaine (0.44-0.98 mg.kg-1.h-1) or bupivacaine (0.10-0.28 mg.kg-1.h-1) in a double-blind fashion. The time to mobilisation, degree of pain relief, blood pressure, respiration and motor function were recorded at regular intervals postoperatively for 40 h. Serum concentrations of lidocaine, its main metabolite monoethylglycinexylidide (MEGX) and bupivacaine were measured at 3, 15 and 40 h. RESULTS: There were no significant differences in the clinical characteristics between the two patient groups. There were no significant differences in the time from the end of surgery to the time the patients were able to stand without support (bupivacaine: median 24 h (interquartile range (IQR): 22-31), lidocaine: median 28 h (IQR 23-40), P = 0.15) or were able to walk without support (bupivacaine: median 46 h (IQR 28-62), lidocaine: median 48 h (IQR 35-54), P = 0.78). No significant differences between the groups were recorded with respect to pain relief, blood pressure, respiration, sedation score and motor function. The plasma concentration of lidocaine and bupivacaine increased significantly during the treatment period (P < 0.01 for both drugs), but not the concentration of MEGX. The highest venous lidocaine concentration was 17.5 mumol/l and the highest bupivacaine concentration was 18.8 mumol/l. There was a significant correlation between the concentration of both lidocaine and bupivacaine and the concentration of alpha 1-acid glycoprotein (AAG) (lidocaine: r = 0.77, P < 0.001, bupivacaine: r = 0.60, P < 0.001), suggesting that the free fraction of the drugs did not increase. No patients showed serious signs of toxicity. The epidural infusion rates remained stable in both groups during the study period. CONCLUSION: There were no clinically or statistically significant differences in the postoperative course after lower abdominal surgery in patients who received an epidural infusion of morphine combined with bupivacaine as compared to patients who received morphine with lidocaine. Further clinical studies to establish the place of lidocaine in postoperative epidural analgesia should be performed.     

A comparison of postoperative analgesia following spinal or epidural anaesthesia for Caesarean section

Postoperative analgesia, using a patient-controlled analgesia system, was studied in 32 women after elective Caesarean section performed under either spinal or epidural anaesthesia. Patients who had spinal anaesthesia had significantly higher pain scores and morphine consumption during the first 4 h postoperatively than patients who had epidural anaesthesia. This situation was reversed between 4 to 8 h postoperatively with patients who had had epidurals having significantly higher pain scores despite higher morphine consumption. After 8 h there was little difference in pain scores or morphine use between the two groups. Total morphine consumption in the first 24 h postoperatively was not significantly different between the two groups.     

Adverse effects of epidural 0.03% bupivacaine during analgesia after cesarean section.

To develop a regimen that would provide good analgesia after cesarean section with minimal side effects in the setting of prolonged (> 24 h) epidural infusion, buprenorphine or fentanyl was combined with 0.03% bupivacaine in a double-blind study of 23 parturients. Patients were randomly assigned to two groups: group I (n = 12), patient-controlled analgesia by epidural infusion of buprenorphine (3 micrograms/mL) with 0.03% bupivacaine; group II (n = 11), patient-controlled analgesia by epidural infusion of fentanyl (2 micrograms/mL) with 0.03% bupivacaine. Plasma for determination of opioid concentrations was obtained at intermittent intervals. Pain relief was similar and satisfactory in both groups. The median overall satisfaction score was higher (10.0 vs 7.5; P < 0.03) for group II. Pruritus was mild in most patients. Nausea and vomiting, which were most disturbing to the patients, were seen only with buprenorphine. No patient had a respiratory rate of < 12 breaths/min. Mean plasma opioid concentrations did not exceed 1 ng/mL during the study. However, four patients (33%) in group I and six patients (55%) in group II experienced sensory loss in the lower extremities, which made ambulation difficult. One patient in each group developed extensive pressure blisters on both heels. These complications led us to terminate the study. We conclude that 0.03% bupivacaine used in combination with an opioid in prolonged epidural infusions produces a high incidence of sensory loss in the lower extremities and is unsuitable for situations in which early ambulation is desired.     

A comparison of 0.1% and 0.2% ropivacaine and bupivacaine combined with morphine for postoperative patient-controlled epidural analgesia after major abdominal surgery

Ropivacaine (ROPI), which is less toxic and produces less motor block than bupivacaine (BUPI), seems attractive for epidural analgesia. Few data are available concerning dose requirements of epidural ROPI when combined with morphine. In this study, we compared the dose requirements and side effects of ROPI and BUPI combined with small-dose morphine after major abdominal surgery. Postoperatively, 60 patients were randomly allocated (double-blinded manner) to four groups: patient-controlled epidural analgesia with the same settings using 0.1% or 0.2% solution of ROPI or BUPI combined with an epidural infusion of 0.1 mg/h of morphine. Pain scores, side effects, motor block, and local anesthetic consumption were measured for 60 h. Pain scores and the incidence of side effects did not differ among the groups. Consumption of ROPI and BUPI were similar in both 0.1% groups. Doubling the concentration significantly reduced the consumption (milliliters) of BUPI (P < 0.05) but not of ROPI. Consequently, using ROPI 0.2% significantly increased the dose administered as compared with ROPI 0.1% (ROPI 0.1% = 314 +/- 151 mg and ROPI 0.2% = 573 +/- 304 mg at Hour 48; P < 0.05). Patient-controlled epidural analgesia with the 0.1% or 0.2% solution of ROPI or BUPI combined with epidural morphine resulted in comparable analgesia. As compared with ROPI 0.1%, the use of ROPI 0.2% increased consumption of local anesthetic without improving analgesia. IMPLICATIONS: Small-dose (0.1%) ropivacaine and bupivacaine have similar potency and result in comparable analgesia and incidence of side effects.     

Intrathecal bupivacaine with morphine or neostigmine for postoperative analgesia after total knee replacement surgery

PURPOSE: To compare the postoperative analgesic efficacy and safety of intrathecal (IT) neostigmine and IT morphine in patients undergoing total knee replacement under spinal anesthesia. METHODS: Sixty patients scheduled for elective total knee replacement under spinal anesthesia were randomly divided into three equal groups which received IT 0.5% hyperbaric bupivacaine 15 mg with either normal saline 0.5 mL, neostigmine 50 microg, or morphine 300 microg. The maximal level of sensory block, duration of analgesia, time to use of rescue analgesics, the overall 24-hr and four-hour interval visual analogue scale (VAS) pain score, and the incidence of adverse effects were recorded for 24 hr after administration. RESULTS: There was no significant difference in maximal level of sensory block among the three groups. The morphine group had a later onset of postsurgical pain and longer time to first rescue analgesics than the neostigmine group (P <0.05). Overall 24-hr VAS pain scores were significantly higher in the saline group vs the morphine and neostigmine groups (P <0.05). Motor block lasted significantly longer in the neostigmine group than in the morphine and saline groups (P <0.05). The incidence of adverse effects was similar in the neostigmine and morphine groups except for pruritus (70%) occurring more frequently in the morphine group than in the neostigmine and saline groups (0%; P <0.05). Overall satisfaction rates were better in the neostigmine group than in the morphine and saline groups (P <0.05). CONCLUSIONS: IT neostigmine 50 microg produced postoperative analgesia lasting about seven hours with fewer side effects and better satisfaction ratings than IT morphine 300 microg.     

硬膜外腔注射氢吗啡酮在剖宫产术后镇痛的临床观察

目的 观察硬膜外腔注射不同剂量盐酸氢吗啡酮对剖宫产术后镇痛的效果和安全性.方法 选择单胎足月于硬膜外麻醉下行剖宫产手术的初产妇60例,按随机数字表法分为A组、B组、C组,每组20例.3组分别于术毕前10 min经硬膜外腔注射5 ml生理盐水稀释的盐酸氢吗啡酮0.1、0.2、0.3 mg.记录术后3、6、12、24 h的疼痛VAS评分,24 h镇痛药物追加的例数及术后副作用发生的情况.结果 术后6、12、24 h的VAS评分C组低于A、B两组,B组低于A组(P＜0.05);镇痛药追加例数C组(2例)少于A组(8例)(P＜0.05);副作用组间比较差异无统计学意义(P＞0.05).结论 硬膜外腔内注射不同剂量的盐酸氢吗啡酮用于剖宫产术后早期可获得良好的镇痛效果,0.3 mg的盐酸氢吗啡酮效果更佳.     

Epidural morphine with butorphanol for postoperative analgesia after cesarean delivery

Epidural morphine has been used more and more to provide long-lasting postoperative analgesia after cesarean delivery. However, the incidence of pruritus (20%-93%) and nausea (17%-60%) detract from the usefulness of epidural morphine. The purpose of this study was to evaluate, in 30 patients having epidural anesthesia for cesarean delivery, the analgesic efficacy and side effects when a combination of epidural morphine, a mu-receptor agonist, and butorphanol, a mu-receptor antagonist and kappa-receptor agonist, was administered. After clamping of the umbilical cord, patients received 4 mg epidural morphine with 3 mL of normal saline (group 1), 4 mg epidural morphine with 1 mg butorphanol and 2 mL of normal saline (group 2), or 4 mg epidural morphine with 3 mg butorphanol (group 3). Patients were monitored for 24 h after administration of the study medications. There were no significant differences between the groups in visual analogue pain scores, time to first analgesic request, respiratory rate, or Trieger dot test performance in the 24 h immediately after these epidural injections. There were three patients in group 1 and one patient in group 2 who experienced oxygen saturations less than 90%. (No patients in group 3 developed an oxygen saturation less than 92%.) The patients in group 3 did not require treatment for pruritus or nausea, a response significantly different (P less than 0.001 and P less than 0.05, respectively) from group 1 or group 2.(ABSTRACT TRUNCATED AT 250 WORDS)     

硬膜外芬太尼和静注吗啡用于子宫切除术后病人自控镇痛

目的 比较病人自控硬膜外芬太尼（PCEAF）和病人自控静注吗啡（PCIAM）在子宫切除术后的镇痛作用。方法 60例病人,进行随机、双盲研究。PCEAF组用芬太尼20μg,锁定时间10分钟;PCIAM组用吗啡1mg,锁定时间7分钟。结果 PCEAF组PCA应用少于PCIAM组（P＜0．01）。PCEAF病人疼痛最高分为20（10－33）,而PCIAM组为32（14－52）（P＜0．05）。PCEAF组在咳嗽时最高评分为31（21－44）,PCIAM组为56（30－70）（P＜0．01）。PCEAF组恶心和嗜睡较少,瘙痒并发症发生率无差异。结论 硬膜外PCA给予芬太尼是安全的,并减少恶心的发生。