Buprenorphine added to the local anesthetic for brachial plexus block to provide postoperative analgesia in outpatients.

BACKGROUND AND OBJECTIVES: Over the past 10 years, several studies have suggested that the addition of certain opiates to the local anesthetic used for brachial block may provide effective, long-lasting postoperative analgesia. One of these studies indicated that the agonist-antagonist, buprenorphine, added to bupivacaine provided a longer period of postoperative analgesia than the traditional opiates, but in this study, it is impossible to determine the relative contributions of the local anesthetic and the opiate to the postoperative analgesia because of the extremely long duration of the anesthesia provided by the local anesthetic, bupivacaine. By repeating the study using a local anesthetic of a shorter duration, the present study delineates more clearly the contribution of the buprenorphine to postoperative analgesia when added to a shorter-acting local anesthetic. METHODS: Forty, healthy, consenting adult patients scheduled for upper extremity surgery were enrolled in the study. Premedication was provided by intravenous midazolam 2 mg/70 kg and anesthesia by a subclavian perivascular brachial plexus block. The patients were assigned randomly to 1 of 2 equal groups based on the agents used for the blocks. The patients in group I received 40 mL of a local anesthetic alone, while those in group II received the same local anesthetic plus buprenorphine 0.3 mg. The study was kept double-blind by having 1 anesthesiologist prepare the solutions, a second anesthesiologist perform the blocks, and a third anesthesiologist monitor the anesthesia and analgesia thereafter, up to and including the time of the first request for an analgesic medication. The data were reported as means (+/- SEM), and differences between groups were determined using repeated measures of analysis of variance (ANOVA) and chi(2), followed by the Fisher exact test for post hoc comparison. A P value of less than.05 was considered to be statistically significant. RESULTS: The mean duration of postoperative pain relief following the injection of the local anesthetic alone was 5.3 (+/- 0.15) hours as compared with 17.4 (+/- 1.26) hours when buprenorphine was added, a difference that was statistically (and clinically) significant (P <.0001). CONCLUSIONS: The addition of buprenorphine to the local anesthetic used for brachial plexus block in the present study provided a 3-fold increase in the duration of postoperative analgesia, with complete analgesia persisting 30 hours beyond the duration provided by the local anesthetic alone in 75% of the patients. This practice can be of particular benefit to patients undergoing ambulatory upper extremity surgery by providing prolonged analgesia after discharge from the hospital.

Simultaneous determination of mepivacaine, tetracaine, and p-butylaminobenzoic acid by high-performance liquid chromatography.

INTRODUCTION: The purpose of the present study was to develop a simple method for the simultaneous determination of mepivacaine, tetracaine, and p-butylaminobenzoic acid (BABA) in human plasma using high-performance liquid chromatography (HPLC) with a multiwavelength detector. METHODS: Human blood samples containing heparin, as an anticoagulant, and physostigmine (100 microg/ml), as an anticholinesterase, or human plasma containing physostigmine were spiked with various concentrations of mepivacaine, tetracaine and, in some cases, BABA. Blood samples were centrifuged and plasma was deproteinized with trifluoroacetic acid (TFA; 7%). After centrifugation, the pH was adjusted to 4.5 and an aliquot of 20, 50 or 100 microl was injected into the HPLC apparatus. The detection was done simultaneously at wavelengths of 214 and 300 nm. Analytical chromatography was done on a Waters microBondapak C(18) reverse-phase column (3.9 x 300 mm; particle size 10 microm) with a 30-min increasing linear gradient of 20-40% acetonitrile+0.05% TFA in H(2)O+0.05% TFA at a flow rate of 1 ml/min. The Waters HPLC system included two pumps, an automatic injector, a column oven, and a M490 multiwavelength detector. Quantification was done using integration of peak areas with peaks of authentic mepivacaine, tetracaine, and BABA standards. RESULTS: Calibration curves for standards of mepivacaine, tetracaine, and BABA were linear in the concentration ranges from 0.1 to 100 microg/ml, and the correlation coefficients exceeded.99 for all compounds. The lower limits of detection were 100 ng/ml for mepivacaine and 50 ng/ml for tetracaine and BABA. The yields for mepivacaine, tetracaine, and BABA were 91+/-2.1%, 82+/-3.3%, and 88+/-2.0% (mean+/-S.E.M., n=6), respectively. Degradation of tetracaine by human plasma at 37 degrees C was inhibited by physostigmine. DISCUSSION: The method is sensitive enough to allow blood concentration determinations of mepivacaine and tetracaine or its metabolite, BABA, following local anesthesia induced by these two drugs, especially when their toxic effect may be present. This method also may be useful in forensic medicine for determination of the cause of death after local anesthesia with mepivacaine and/or tetracaine.

A comparative efficacy study of hyperbaric 5% lidocaine and 1.5% lidocaine for spinal anesthesia.

UNLABELLED: We compared the clinical efficacy of 1.5% lidocaine in dextrose 7.5% in water, which is currently available as a commercial preparation but approved for use only in obstetrical patients, with the traditional 5% lidocaine in dextrose 7.5% in water for spinal anesthesia in patients undergoing lower abdominal procedures. Fifty-one male patients scheduled to undergo inguinal herniorrhaphy were randomly divided into two groups based on the spinal anesthetic received: Group I received 1.5% lidocaine in dextrose 7.5% in water, and Group II received 5% lidocaine in dextrose 7.5% in water. After intrathecal injection of the anesthetic, each patient was evaluated for the speed of onset, the time to recovery, and the quality of the surgical anesthesia and motor block that ensued by an anesthesiologist blinded to the technique. With the exception of the patients in Group I, who achieved a higher dermatome level of sensory analgesia, we were unable to demonstrate any significant clinical differences between the two lidocaine solutions. Our results indicate that lidocaine 1.5% in dextrose 7.5% in water is clinically indistinguishable from the 5% solution as a spinal anesthetic for lower abdominal surgery. IMPLICATIONS: In this study, two concentrations of lidocaine are compared as spinal anesthetics in 51 male patients undergoing inguinal hernia repair. Patients were assessed for the onset, quality, and duration of the spinal block. The study results indicate that 1.5% lidocaine is as effective as the 5% solution as a spinal anesthetic for patients undergoing inguinal hernia repair.

Relief of intractable cancer pain by human chromaffin cell transplants: experience at two medical centers.

In addition to its possible role as a replacement source in CNS degenerative diseases, neural transplantation may be used to augment the normal production of neuroactive substances. Our laboratory at the University of Illinois at Chicago has shown, in both acute and chronic pain models, that transplantation of adrenal medullary tissue or isolated chromaffin cells into CNS pain modulatory regions can reduce pain sensitivity in rodents. Chromaffin cells were chosen as the donor source since they produce high levels of both opioid peptides and catecholamines, substances which reduce pain sensitivity when injected locally into the spinal subarachnoid space. The analgesia produced by these transplants probably results from the release of both opioid peptides and catecholamines since it can be blocked or attenuated by both opiate and adrenergic antagonists. Studies indicate that even over long periods there is no apparent development of tolerance. Promising results have been obtained in preliminary clinical studies using allografts of adrenal medulla to relieve cancer pain. This clinical review encompasses results at two Medical Centers-University of Illinois at Chicago and University Paul Sabatier, Toulouse, France-in assessing efficacy of subarachnoid adrenal medullary transplantation for alleviating cancer pain. Our clinical and autopsy data strongly support our previous laboratory studies, i.e., that chromaffin cell transplants into the subarachnoid space represent a promising new approach to the alleviation of chronic pain. It is suggested that further clinical studies are now warranted.

Addition of bicarbonate to plain bupivacaine does not significantly alter the onset or duration of plexus anesthesia.

BACKGROUND AND OBJECTIVES: In an effort to elucidate further the effect of alkalinization of bupivacaine on its anesthetic effect, a study was undertaken using alkalinized and non-alkalinized bupivacaine for lumbar plexus block and comparing the results with those obtained previously with brachial plexus block. METHODS: Thirty consenting adult patients about to undergo lower extremity surgery under regional anesthesia were selected for the study. All of the patients received an inguinal paravascular lumbar plexus block ("3-in-1 block"), along with a sciatic block to allow the anticipated surgery to be carried out. The patients were divided into two groups, one receiving plain "alkalinized" 0.5% bupivacaine; the other receiving plain "non-alkalinized" 0.5% bupivacaine. After each lumbar plexus block, the onset and duration of analgesia and anesthesia of the nerves derived from the lumbar plexus were determined by an independent investigator who was unaware of which solution had been administered. RESULTS: There was no statistically significant difference between the two groups with respect to the onset or duration of anesthesia and analgesia. CONCLUSIONS: The data obtained in the present study indicate that alkalinization of non-epinephrine-containing bupivacaine does not reduce the latency or increase the duration of analgesia or anesthesia after lumbar plexus block. Since most of the studies that do show such an effect of alkalinization were carried out using epinephrine-containing bupivacaine, it is postulated that in those studies alkalinization contributed to the decrease in latency and increase in duration, not so much by providing an increased amount of local anesthetic in the free base form, but by reactivating epinephrine's vasoconstrictor activity, which is inactivated by a low pH.

Subarachnoid adrenal medullary transplants for terminal cancer pain. A report of preliminary studies.

BACKGROUND: The prolonged use of opioids to treat intractable pain with currently available therapeutic modalities is often unsatisfactory, usually because of tolerance or complications. Extensive studies carried out in the authors' laboratories have indicated that the transplantation of adrenal medullary tissue into the spinal subarachnoid space can significantly reduce pain in animal pain models, most likely via release of opioid peptides and catecholamines. The current study was undertaken to assess the feasibility and efficacy of subarachnoid adrenal medullary transplantation in alleviating terminal cancer pain in humans. METHODS: Two milliliters of human adrenal medullary tissue were prepared in the laboratory and then transplanted via lumbar puncture into the subarachnoid space in five patients suffering from terminal cancer pain. Pain scores (VAS), functional activity, and opioid intake were assessed and recorded before and after the transplantation procedure. In addition, CSF samples were collected before and (when possible) at fixed intervals after transplantation for biochemical and cytologic analysis. RESULTS: Four of the five patients demonstrated progressive decreases in pain scores after the transplant procedure, with concomitant reductions in opioid intake. Three of these four patients remained pain free, two for over 10 months, while the other had a recurrence of her pain after surgery for spinal cord compression secondary to metastases 10 weeks after transplant. The fifth patient had no pain reduction by 1 month after the procedure, and refused further followup. After the transplants, spinal CSF samples revealed increased concentrations of met-enkephalin in three of the five patients, and increased concentrations of catecholamines in the four patients in whom they were determined. CONCLUSIONS: The results obtained in this study indicate that subarachnoid adrenal medullary transplantation may provide a unique and effective approach to the management of intractable chronic pain in humans.

Relationship between time of treatment of acute herpes zoster with sympathetic blockade and prevention of post-herpetic neuralgia: clinical support for a new theory of the mechanism by which sympathetic blockade provides therapeutic benefit.

BACKGROUND AND OBJECTIVES: Since Rosenak's original report more than 50 years ago as to the efficacy of sympathetic blocks in terminating acute herpes zoster, many investigators have reported that a more important benefit of this form of therapy is the prevention of post-herpetic neuralgia. However, most of these reports have indicated that sympathetic blocks are effective in preventing post-herpetic neuralgia only if applied soon after the onset of the acute phase of the disease; in fact, if applied too late, this form of therapy failed to prevent the development of post-herpetic neuralgia. The present study was carried out to determine more precisely the relationship between the time of treatment of acute herpes zoster and the prevention of post-herpetic neuralgia and to attempt to correlate this time with the authors' previously published theory on the mechanism by which sympathetic blocks provide the therapeutic benefit. METHODS: The present study was a retrospective review of 122 patients treated at variable intervals after the onset of acute herpes zoster. Data tabulated included the duration of symptoms at the time of treatment, the number of sympathetic blocks required to provide relief, and the efficacy of the sympathetic blockade in terminating the acute phase of herpes zoster and then preventing the development of post-herpetic neuralgia. RESULT: According to the data obtained in this retrospective study, sympathetic blocks terminated the pain of acute herpes zoster and prevented or relieved post-herpetic neuralgia in more than 80% of patients treated within 2 months of the onset of the acute phase of the disease, after which time the success rate decreased drastically. CONCLUSION: Sympathetic blockade applied within the first 2 months after the onset of acute herpes zoster terminated the acute phase of the disease, probably by restoring intraneural blood flow, thus preventing the death of the large fibers and avoiding the development of post-herpetic neuralgia. If sympathetic blocks were to be carried out after 2 months, the damage to the large fibers would be irreversible, and this therapeutic modality would not be able to prevent the development of post-herpetic neuralgia.

A comparative study of 0.25% ropivacaine and 0.25% bupivacaine for brachial plexus block.

The present study compares the effectiveness of 0.25% ropivacaine and 0.25% bupivacaine in 44 patients receiving a subclavian perivascular brachial plexus block for upper extremity surgery. The patients were assigned to two equal groups in this randomized, double-blind study; one group received ropivacaine 0.25% (112.5 mg) and the other, bupivacaine 0.25% (112.5 mg), both without epinephrine. Onset times for analgesia and anesthesia in each of the C-5 through T-1 brachial plexus dermatomes did not differ significantly between the two groups. The mean onset time for analgesia ranged from 11.2 to 20.2 min, and the mean onset time for anesthesia ranged from 23.3 to 48.2 min. The onset of motor block differed only with respect to paresis in the hand, with bupivacaine demonstrating a shorter onset time than ropivacaine. The duration of sensory and motor block also was not significantly different between the two groups. The mean duration of analgesia ranged from 9.2 to 13.0 h, and the mean duration of anesthesia ranged from 5.0 to 10.2 h. Both groups required supplementation with peripheral nerve blocks or general anesthesia in a large number of cases, with 9 of the 22 patients in the bupivacaine group and 8 of the 22 patients in the ropivacaine group requiring supplementation to allow surgery to begin. In view of the frequent need for supplementation noted with both 0.25% ropivacaine and 0.25% bupivacaine, we do not recommend using the 0.25% concentrations of these local anesthetics to provide brachial plexus block.

A dual-chambered syringe that allows identification of the epidural space using the loss of resistance technique with air and with saline.

BACKGROUND AND OBJECTIVES: Each of the two most widely used techniques for identification of the epidural space, the loss of resistance technique with air and the loss of resistance technique with liquid, has certain advantages and disadvantages. A new syringe is described that has two chambers, one to contain air and the other to contain liquid, to combine the advantages of air with the advantages of liquid, and to prevent the disadvantages of each. METHODS: Twenty consecutive adult patients scheduled to receive epidural injections for surgery, obstetrics, or pain control were selected for study. This was an open study, and the EpIdent syringe was used as the only means of identifying the epidural space in every case. RESULTS: The EpIdent syringe easily and effectively identified the epidural space in all of the patients, with no adverse or unpleasant side effects. Successful identification of the space was documented by the production of adequate anesthesia after the injection of an appropriate volume or local anesthetic. There were no complications. CONCLUSIONS: The successful use of the EpIdent syringe in this preliminary study of 20 patients indicates that it provides a simple, safe, and effective means of identifying the epidural space. It allows the use of a plastic syringe (instead of glass) and avoids the unpleasant or untoward effects associated with currently used loss of resistance techniques.