Mg Of Bupivacaine Research Articles

An assessment of the value of rectus sheath block for postlaparoscopic pain in gynecologic surgery

To compare the effect of the bilateral rectus sheath block (BRSB) by bupivacaine in decreasing postlaparoscopic pain with the intraperitoneal (IP) and intraincisional (II) use of this drug. Randomized, double-blind, clinical trial (Canadian Task Force Classification I). University teaching hospital. Ninety-one women with unexplained infertility. Patients were randomly allocated to one of three groups. In group I, BRSB was performed with 25 mg of bupivacaine. For groups II and III, IP and II instillation, respectively, of 25 mg of bupivacaine was performed. Postoperative pain was assessed by visual analog pain score (VAS) 1, 6, 10, and 24 hours postoperatively. The VAS was significantly lower in group I at 6 hours (p <.001) and 10 hours (p <.004) after laparoscopy. Bilateral rectus sheath block can effectively decrease postlaparoscopic pain at 6 and 10 hours after the operation when compared with IP and II use of bupivacaine.

A Prospective, Randomized, Double-Blind Comparison of Unilateral Spinal Anesthesia with Hyperbaric Bupivacaine, Ropivacaine, or Levobupivacaine for Inguinal Herniorrhaphy

In 60 patients undergoing inguinal hernia repair, we compared the clinical profile of unilateral spinal anesthesia produced with either 8 mg of hyperbaric bupivacaine 0.5% (n = 20), 8 mg of hyperbaric levobupivacaine 0.5% (n = 20), or 12 mg of hyperbaric ropivacaine 0.5% (n = 20). The study drug was injected slowly through a 25-gauge Whitacre directional needle and patients maintained the lateral decubitus position for 15 min. The onset time and intraoperative efficacy were similar in the three groups. The maximal level of sensory block on the operative and nonoperative sides was T6 (T12-5) and L3 (/[no sensory level detectable]-T4) with bupivacaine, T8 (T12-5) and L3 (/-T3) with levobupivacaine, T5 (T10-2) and T11 (/-T3) with ropivacaine (P = 0.11, P = 0.23, respectively). Complete regression of spinal anesthesia occurred after 166 +/- 42 min with ropivacaine, 210 +/- 63 min with levobupivacaine, and 190 +/- 51 min with bupivacaine (P = 0.03 and P = 0.04, respectively); however, no differences were observed in time for home discharge (329 +/- 89 min with bupivacaine, 261 +/- 112 min with levobupivacaine, and 332 +/- 57 min with ropivacaine [P = 0.28]). We conclude that 8 mg of levobupivacaine or 12 mg of ropivacaine are acceptable alternatives to 8 mg of bupivacaine when limiting spinal block at the operative side for inguinal hernia repair.

A Comparison of Duration of Analgesia of Intrathecal 2.5 mg of Bupivacaine, Ropivacaine, and Levobupivacaine in Combined Spinal Epidural Analgesia for Patients in Labor

A Comparison of Duration of Analgesia of Intrathecal 2.5 mg of Bupivacaine, Ropivacaine, and Levobupivacaine in Combined Spinal Epidural Analgesia for Patients in Labor

MULTIDISCIPLINARY PAIN ABSTRACTS: 4 . Anesthesia (4)

In this study the authors investigated the duration of labor analgesia produced by a small dose of spinal bupivacaine/fentanyl alone or in combination with a small dose of morphine. Sixty parturients were enrolled in this placebo‐controlled, double‐blinded, randomized trial. All women received a spinal injection of 12.5 μg of fentanyl with 2 mg of bupivacaine. The morphine group (MBF) also received 125 μg of morphine; the placebo group (BF) received saline. Pain scores were &lt;3 of 10 within 10 minutes of the injection. The median duration of analgesia was similar between groups (89 minutes versus 84 minutes), and only 20% of the MBF group experienced prolonged analgesia. During subsequent epidural analgesia, the MBF group had a significantly lesser rate of breakthrough pain (0.15 ± 0.14 episodes per hour versus 0.26 ± 0.18 episodes per hour). Also, during the first 24 hours postpartum, the MBF group required significantly fewer medications (3.3 ± 3.7 doses versus 4.7 ± 3.5 doses). Intrathecal injection of this small dose of bupivacaine/fentanyl produced a rapid onset of labor analgesia; the addition of a small dose of morphine did not significantly prolong analgesia, but it improved subsequent pain relief, as measured by the rate of breakthrough pain and postpartum medication requirements. This may provide a clinically useful means of improving intrapartum and postpartum pain relief. A small dose of intrathecal fentanyl 12.5 μg and bupivacaine 2 mg produces effective labor analgesia lasting for approximately 85 minutes. The addition of a small 125‐ μg dose of morphine improves pain control during subsequent epidural analgesia and reduces the requirements for postpartum pain medications.

Prolongation of epidural bupivacaine effects with hyaluronic acid in rabbits

To assess the prolongation of epidural bupivacaine by hyaluronic acid viscous formulations we designed a cross-over study in rabbits. Different doses of bupivacaine (3 or 6 mg) either as a solution (bupivacaine hydrochloride), or as viscous formulations with hyaluronic acid (bupivacaine base and bupivacaine hydrochloride) were administered in a rabbit model of epidural anesthesia. In the first part of the study, in vitro release characteristics were determined. Then pharmacodynamic effects and pharmacokinetic profiles of each bupivacaine formulation were studied. The rank order release rate of bupivacaine in vitro was always hydrochloride solution⪢viscous physical mixture of bupivacaine with hyaluronic acid>viscous ionic complex of bupivacaine base with hyaluronic acid. Onset time of epidural anesthesia was similar whatever the formulation of bupivacaine used. We did not find any blockade prolongation when 3 mg bupivacaine was administered, but significant blockade prolongations were observed with viscous formulations incorporating 6 mg bupivacaine. The observed reduction in the absorption rate of bupivacaine into the systemic circulation for both viscous hyaluronic formulations after 6 mg of bupivacaine may explain the prolongation of spinal effects. Drug release and duration of action were found to be viscosity controlled as linear relationships were found between pharmacodynamic effects and viscosity. Our results were in accordance with those reported with bupivacaine–cyclodextrin complex, another formulation with a molecular dispersion of the drug, resulting in a moderate prolongation of action.

A Comparison of Duration of Analgesia of Intrathecal 2.5 mg of Bupivacaine, Ropivacaine, and Levobupivacaine in Combined Spinal Epidural Analgesia for Patients in Labor

We assessed the duration of labor analgesia rendered by intrathecal (IT) local anesthetics as the sole drugs. In this randomized, controlled, and double-blinded study, labor analgesia was induced using combined spinal-epidural technique in 60 ASA physical status I nulliparous parturients with IT bupivacaine 2.5 mg (group B), ropivacaine 2.5 mg (group R), or levobupivacaine 2.5 mg (group L). Pain scores (0-100 visual analog scale) and blood pressure were recorded pre-block and for the first 30 min post-block. The degree of motor block and the highest sensory block were also monitored. The duration of analgesia (our primary outcome) was the longest in group B but was similar between groups R and L (mean +/- SE, 76.3 +/- 5.9 min versus 52.6 +/- 4.0 min and 51.5 +/- 3.4 min, respectively, P < 0.05). Group B had the most frequent incidence of lower limb motor block but there was no difference between groups R and L (5 of 20 parturients versus 2 of 20 and 0 of 20, respectively, P < 0.05). The profile of the other side effects was indistinguishable between the groups. With the current regimen, IT bupivacaine produced the longest duration of labor analgesia. Intrathecal 2.5 mg bupivacaine significantly prolongs the duration of analgesia in laboring patients compared with ropivacaine or levobupivacaine. This suggests that, at clinically relevant doses, bupivacaine may have greater potency.

Poster 179: Cauda Equina syndrome after spinal anesthesia with bupivacaine: a case report.

Setting: Tertiary care hospital. Patient: A 83-year-old man. Case Description: The patient was admitted for orchiectomy. He received spinal anesthesia with 15mg of bupivacaine at the L5-S1 level. Approximately 24 hours later he developed severe pain, weakness, and sensory deficits in his lower extremities. Lower-extremity arterial and venous studies were unremarkable. The patient was diagnosed with probable cauda equina syndrome secondary to bupivacaine neurotoxicity. Assessment/Results: The patient was treated with steroids with little improvement. Subsequently, he was admitted to inpatient rehabilitation. Exam revealed hypersensitivity in the lower extremities. He had 3/5 lower-extremity strength bilaterally and was nonambulatory. Sensory exam and range of motion were limited by severe hyperesthesia. A catheter was required for urinary retention. The patient was started on a fentanyl patch, gabapentin (Neurontin), and physical and occupational therapy. By discharge, his pain, strength, and function had improved. He was ambulating 100ft with a walker, transferring with stand by assist, and was continent of bowel and bladder. He did, however, have persistent mild lower-extremity weakness and sensory deficits. Discussion: Spinal anesthesia with local anesthetics has been associated with cauda equina syndrome. Increased risk occurs with continuous spinal anesthesia, high doses, and use of lidocaine. Patients with underlying neurologic conditions may also have a higher susceptibility. The risk of cauda equina injury after bupivacaine spinal anesthesia is 1 in 10,000. The mechanism of neurotoxicity is unknown. Treatment is supportive and narcotic analgesics are typically required to control pain. Conclusion: Cauda equina syndrome is a rare complication of spinal anesthesia. It can cause significant pain and impairment.

Combination Spinal Analgesic Chemotherapy: A Systematic Review

Combination Spinal Analgesic Chemotherapy: A Systematic Review

Combination spinal analgesic chemotherapy: a systematic review.

Combination spinal analgesic chemotherapy: a systematic review.

An Analysis of Excitatory Amino Acids, Nitric Oxide, and Prostaglandin E2 in the Cerebrospinal Fluid of Pregnant Women: The Effect on Labor Pain

It is still unclear which neurotransmitters are involved in labor pain. We measured the concentrations of excitatory amino acids, nitric oxide, and prostaglandin E2 in the cerebrospinal fluid (CSF) of pregnant women, particularly in those with labor pain. The patients included in the study consisted of women who underwent cesarean delivery either with labor pain (Labor Pain group, n = 40) or without labor pain (Nonlabor Pain group, n = 58). All patients received spinal anesthesia (intrathecal injection of 10-12 mg of bupivacaine) for the operation, and 2 mL of CSF was collected before bupivacaine injection. Concentrations of aspartate and glutamate (0.50 +/- 0.06 microM and 0.79 +/- 0.10 microM, respectively) were significantly larger in the Labor Pain group than in the Nonlabor Pain group (0.35 +/- 0.03 microM and 0.54 +/- 0.04 microM, P < 0.05). There were no significant differences in the concentrations of nitric oxide and prostaglandin E2 between the groups. A positive correlation was found between CSF concentrations of excitatory amino acids and labor pain. The excitatory amino acids, aspartate and glutamate, play a role in labor pain. N-methyl-D-aspartate receptor antagonists may be useful for labor pain and postlabor uterine contraction pain relief.

Long-Term Intrathecal Infusion of Drug Combinations for Chronic Back and Leg Pain

Continuous intrathecal infusion of analgesic drugs by implantable pumps is recognized as an established treatment option for patients with chronic pain resistant to oral or parenteral medication. Polyanalgesia, the simultaneous use of more than one intrathecal analgesic drug, is practiced relatively often, but there are only a few published clinical studies on intrathecal polyanalgesia for chronic nonmalignant pain. This pilot study represents a long-term evaluation of a treatment regimen consisting of intrathecal morphine admixed with bupivacaine, clonidine, or midazolam in patients with chronic nonmalignant back and leg pain due to degenerative lumbar spinal disease. Twenty-six adult patients have been treated by intrathecal programmable pump-controlled infusion of analgesic drugs and followed for up to 3.5 years (27 ± 11 months). Combination of morphine with a second drug was used in 10 cases, morphine with 2 additional drugs in 12 cases, and morphine with 3 additional drugs in 4 cases. Mean daily doses at 24 months after pump implantation were 6.2 ± 2.8 mg for morphine, 2.5 ± 1.5 mg for bupivacaine, 0.06 ± 0.03 mg for clonidine, and 0.8 ± 0.4 mg for midazolam. Nineteen patients reported excellent or good long-term treatment results, 6 patients had sufficient results, and only 1 patient complained of poor therapeutic efficacy. No long-term clinical side effects of intrathecal polyanalgesia were noted. Mean morphine dose had to be increased from 1.2 mg at baseline to 5.1 mg at 24 months due to tolerance development and disease progression. This experience suggests that intrathecal polyanalgesia employing morphine combined with additional nonopioid drugs can have a favorable analgesic efficacy in patients with complex chronic pain of spinal origin, and lacks major drug-related complications.

The pharmacokinetics and pharmacodynamics of bupivacaine-loaded microspheres on a brachial plexus block model in sheep.

We evaluated bupivacaine-loaded microspheres (B-Ms) using a brachial plexus block model in sheep. In the first step, pharmacokinetic characterization of 75 mg bupivacaine hydrochloride (B-HCl) (IV infusion and brachial plexus block) was performed (n = 12). In the second step, a brachial plexus block dose response study of B-HCl was performed with 37.5 mg, 75 mg, 150 mg, 300 mg, and 750 mg. As a comparison, evaluations were performed using a 750-mg bupivacaine base (B). In the third step, evaluations of brachial plexus block were performed with B-Ms (750 mg of B as B-Ms) using two formulations, 60/40 and 50/50 (w/w %); drug-free microspheres were also evaluated. Toxicity evaluations were also performed after IV administration of B-HCl (750 mg and 300 mg), B-Ms (750 mg), and drug-free microspheres (30 mL over 1 min). As the B-HCl dose increased, the time of onset of block decreased and the duration of complete motor blockade increased at the expense of an increase in bupivacaine plasma concentrations. The time of maximum concentration appeared to be independent of the B-HCl dose. In brachial plexus block, a 37.5-mg dose of B-HCl did not induce motor blockade whereas a dose of 750 mg of B-HCl was clinically toxic. In the case of IV administration, doses of 300 mg of B-HCl were as toxic as 750 mg of B-HCl. Compared with the 75 mg of B-HCl administration for brachial plexus block, administration of 750 mg of B as B-Ms increased the duration of complete motor blockade without significant difference in maximum concentration. No significant clinical difference between the two formulations of B-Ms was demonstrated. The IV administration of B-Ms was safe. We conclude that the controlled release of bupivacaine from microspheres prolonged the brachial plexus block without obvious toxicity. Administration of 750 mg of bupivacaine as loaded-microspheres resulted in prolongation of brachial plexus block in sheep. The peak plasma concentration was not significantly larger than that obtained with 75 mg of plain bupivacaine. The motor blockade was increased more than six times compared with 75 mg plain bupivacaine.

Combined spinal-epidural analgesia for labor

Combined spinal-epidural analgesia is a technique that provides rapid-onset, profound epidural analgesia for laboring parturients at almost any stage of labor. The most commonly used technique is a needle-through-needle technique in which the epidural space is identified with an epidural needle, and then a long spinal needle is inserted through the epidural needle and into the cerebrospinal fluid. Intrathecal fentanyl, 15 to 25 μg ± 1 to 2.5 mg of bupivacaine, or 2.5 to 5 μg of sufentanil ± 1 to 2.5 mg of bupivacaine are injected to produce analgesia. The epidural needle is removed and an epidural catheter inserted. Analgesia is maintained by low-dose, patient-controlled epidural analgesia; continuous infusion epidural analgesia; or intermittent top-ups. Pruritus is a very common side effect. Respiratory depression is rare but of great concern. Current literature favors low-dose epidural analgesia in labor as leading to the best patient and obstetric outcomes. Both low-dose conventional epidural analgesia and combined spinal-epidural analgesia produce similar outcomes. The main advantage of combined spinal-epidural analgesia is its predictable profound analgesia in parturients during late labor or when labor is progressing rapidly. Copyright © 2001 by W.B. Saunders Company

Intrathecal Anesthesia: Ropivacaine Versus Bupivacaine

We compared intrathecal ropivacaine to bupivacaine in patients scheduled for transurethral resection of bladder or prostate. Doses of ropivacaine and bupivacaine were chosen according to a 3:2 ratio found to be equipotent in orthopedic surgery. One hundred patients were randomly assigned to blindly receive either 10 mg of isobaric bupivacaine (0.2%, n = 50) or 15 mg of isobaric ropivacaine (0.3%, n = 50) over 30 s through a 27-gauge Quincke needle at the L2-3 level in the sitting position. Onset and offset times for sensory and motor blockades and mean arterial blood pressure were recorded. Pain at surgical site requiring supplemental analgesics was recorded. Cephalad spread of sensory blocks was higher with bupivacaine (median level, cold T(4) and pinprick T(7)) than with ropivacaine (cold T(6) and pinprick T(9)) (P<0.001). Eight patients in Group Ropivacaine received IV alfentanil (P<0.01). Onset time (mean +/- SD) to T(10) anesthesia and offset time at L2 were not different (bupivacaine = 13 +/-8 min, 127+/-41 min; ropivacaine = 11+/-7 min, 105+/-29 min). Complete motor blockade occurred in 43 patients with bupivacaine and in 41 patients with ropivacaine (not significant). Total duration of motor blockade was not different. No difference in hemodynamic effects was detected between groups. No patient reported back pain. We conclude that 15 mg of intrathecal ropivacaine provided similar motor and hemodynamic effects but less potent anesthesia than 10 mg of bupivacaine for endoscopic urological surgery.

Transcervical or intraperitoneal analgesia for laparoscopic tubal sterilization: a randomized controlled trial

Objective: To test the effectiveness of analgesia administered transcervically through a uterine manipulator compared with direct topical application to the fallopian tubes for relief of postoperative pain after interval laparoscopic tubal sterilization. Methods: Sixty-one women who had laparoscopic sterilization were enrolled in a randomized, double-masked clinical trial comparing analgesia with 75 mg of bupivacaine administered through a uterine manipulator with 75 mg of bupivacaine applied directly to the fallopian tubes through a secondary trocar. Results were evaluated using visual analog scale pain levels, time of administration of analgesics, total analgesics required, and recovery room times. We calculated that a sample size of 60 women would detect a 30% difference in pain levels with a power of 80% at a significance level of .05. Results: In the 59 women who completed the study, there were no differences in the two groups in pain levels, amounts of medications used, or times to administration of postoperative analgesia. Mean recovery room time was shorter in the group given analgesia transcervically, but that difference was not statistically significant. Conclusion: There were no significant differences in postoperative pain relief between transcervical administration and topical application of analgesia for laparoscopic tubal sterilization.

Low-dose intrathecal clonidine combined with sufentanil as analgesic drugs in abdominal gynecological surgery

Study Objectives: To determine whether a low dose of spinal clonidine either alone or combined with sufentanil would provide effective analgesia following abdominal surgery, as a supplement to bupivacaine spinal anesthesia. Design: Randomized double-blind study. Setting: Gynecological surgery, teaching hospital. Patients: 73 ASA physical status I and II patients undergoing gynecological abdominal surgery with spinal anesthesia. Interventions: Patients were randomly assigned to one of four groups and prospectively studied to examine anesthesia, analgesia, and adverse effects. The control group received saline as the test drug; the sufentanil group received 10 μ g of sufentanil; the clonidine group received 30 μ g of clonidine; and the sufentanil/clonidine group received 5 μ g of sufentanil plus 15 μ g of clonidine. All groups received intrathecal 15 mg of bupivacaine (3 mL) plus the intrathecal test drug (2 mL). The concept of visual analog scale (VAS) was introduced. All patients were premedicated with intravenous midazolam. Rescue analgesics were available. Measurements and Main Results: The groups were demographically the same. Sensory block to pinprick at 10 min was higher for clonidine and sufentanil/clonidine groups compared to the control group (p < 0.02). Anesthetic time (Bromage score 2) was also longer for clonidine and sufentanil/clonidine groups compared to the control and sufentanil groups (p < 0.05). Time to first rescue analgesics was shorter in the control group compared to the other groups (p < 0.02). The number of IM diclofenac dose injections in 24 hours was higher in the control group compared to all other groups (p < 0.05). The incidence of adverse effects and ephedrine consumption were similar among groups. Conclusions: Intrathecal 15- and 30-μ g clonidine doses expanded the anesthesia sensory block and duration of motor block, and provided analgesia.

Intrathecal Ropivacaine for Ambulatory Surgery: A Comparison Between Intrathecal Bupivacaine and Intrathecal Ropivacaine for Knee Arthroscopy

GAUTIER, PH. E.; DE KOCK, M.; VAN STEENBERGE, A.; POTH, N.; LAHAYE-GOFFART, B.; FANARD, L.; HODY, J. L. Author Information

Effect of Maternal Ambulation on Labour With Low-Dose Combined Spinal-Epidural Analgesia

Some believe that confining women to bed will prolong labor and make it more painful, but other studies have failed to show any effect of maternal ambulation. This trial examined the effects of walking on the duration of labor, amount of anesthesia used, mode of delivery, and the infant’s condition. The study enrolled 229 nulliparous women who requested regional analgesia in the form of a low-dose combined spinal-epidural block. The initial subarachnoid injection contained 25 μg of fentanyl and 2.5 mg of bupivacaine. When the spinal block began to wear off, 15 ml of 0.1 percent bupivacaine containing 2 μg fentanyl/ml was injected through the epidural catheter. Subsequent doses of 10 to 15 ml of the epidural mixture were given as needed. A group of 110 women were allowed to get out of bed, and the remaining 110 stayed in bed. All participants had a singleton pregnancy at 36 to 42 weeks’ gestation and a cephalic presentation. About one-third of the women had labor induced. Some of the control women left bed for short periods, and fewer than half of the ambulatory group spent 30 percent or more of their block time out of bed. In some cases, motor block was responsible, but the most common reason was fatigue. Whether women were assigned to the walking group made no difference in the duration of labor or analgesic requirements, and there was no difference in modes of delivery between the two groups. Very few neonates had low 5-minute Apgar scores, and infants in both groups had similar blood gas values. More than 90 percent of women in both groups were totally satisfied with their analgesia. Several women had generalized backache or tenderness at the injection site. Two parturients had to be catheterized because of urinary retention. No definite benefit of ambulation during labor emerged from this study, but there also were no apparent disadvantages. Mothers do welcome the freedom afforded by combined spinal-epidural analgesia. Conceivably, a study looking at the duration and timing of ambulation would demonstrate effects not noted in the present trial. Anaesthesia 1999;54:535–539

A dose–response study of epidural liposomal bupivacaine in rabbits

Liposomes are drug delivery systems used to prolong local effects of bupivacaine. We studied the relationships between motor and hemodynamic changes and epidural doses of plain bupivacaine (P) and liposomal bupivacaine (L) in rabbits equipped with chronical lumbar epidural and femoral arterial catheters. Liposomal (phosphatidylcholine–cholesterol) suspensions contained 20 mg ml −1 of lipid, and different doses of bupivacaine (Lipo 7.5=7.5-; Lipo 3.7=3.75-; Lipo 2.5=2.5-; Lipo 1.2=1.25-; and Lipo 0.7=0.65-mg of bupivacaine per ml). Forty rabbits were randomly assigned to five groups to receive epidural anesthesia (1 ml) as follows: Groups I to V received 0.65 to 7.5 mg of bupivacaine as P then as L. Release rate of bupivacaine from liposome was significantly slower using Lipo 3.7 than after Lipo 2.5 ( T d was 3.9 h and 1.7 h respectively). Increasing the doses of L and P resulted in faster onset time for complete motor blockade and in a prolonged duration of motor effects. Liposomal formulation appears to be a powerful delivery system to prolong the motor effects of bupivacaine since E 50 was lower and E max higher than after the use of plain solution ( E 50 4.49±1.81 mg and E max 152±40 min for P; and E 50 2.61±0.23 mg and E max 202±9 min for L). Hemodynamic changes were linearly related to doses of bupivacaine injected. The best bupivacaine-to-lipid ratio to prolong motor effects using our model was 3.75 mg and 20.0 mg respectively (Lipo 3.7).

The Epidural "Top-Up" in Combined Spinal-Epidural Anesthesia

The reinforcement of anesthesia by an epidural "top-up" in combined spinal-epidural anesthesia may be explained by a dual mechanism: a volume effect compressing the dural sac and a local anesthetic effect. The purpose of our study was to investigate the relative importance of each of these factors. Fifty patients scheduled for lower limb orthopedic surgery under combined spinal-epidural anesthesia were randomly allocated to one of five groups comprising 10 patients each. Using a needle-through-needle technique, all patients received a subarachnoid injection of 10 mg of plain bupivacaine and an epidural catheter. After the maximal level of sensory blockade as a result of the subarachnoid injection had been established, an epidural top-up was given according to the randomization code. Patients in Group 1 received 10 mL of bupivacaine 0.25%; patients in Group 2 received 10 mL of saline; patients in Group 3 received 5 mL of bupivacaine 0.5%; patients in Group 4 received 5 mL of saline; and patients in Group 5 received no epidural top-up. The maximal level of sensory blockade was then assessed for an additional 30 min. In Groups 1-4, the maximal level of sensory blockade increased significantly, whereas there was no significant increase in Group 5. There was no significant difference in the increase in the maximal level of sensory blockade among Groups 1-4. We conclude that, under the conditions of our study, there is no difference between 5 and 10 mL with regard to the volume effect of an epidural top-up in combined spinal-epidural anesthesia and that to produce an additional local anesthetic effect with bupivacaine, the dose must be larger than 25 mg. Implications: In combined spinal-epidural anesthesia, an epidural "top-up" may increase the maximal level of sensory blockade by means of a volume effect and a local anesthetic effect. In this study, volumes of 5 and 10 mL produced a similar increase, and 25 mg of bupivacaine was insufficient to produce an additional local anesthetic effect. (Anesth Analg 1999;88:810-4)