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.

Anesthetic management of toxic epidermal necrolysis: report of three adult cases.

Toxic epidermal necrolysis is a rare but acute life-threatening syndrome in which the epidermis blisters and peels in large sheets. In general, patients with this syndrome are managed as severe second-degree burn patients, but special consideration should be given to mucous membrane involvement that reduces fluid intake and worsens the fluid deficit, systemic involvement that makes these patients hemodynamically unstable, and progression of cutaneous lesions that enhances the risk of infection and sepsis.

Canister tip orientation and residual volume have significant impact on the dose of benzocaine delivered by Hurricaine spray.

Delivered quantities of 20% benzocaine spray (Hurricaine; Beutlich L.P. Pharmaceuticals, Waukegan, IL) are estimated by counting the number of sprays or the spraying time. Because Hurricaine spray supplies a continuous (albeit nonmetered) stream of benzocaine, neither method addresses delivered dose. We hypothesized that dose per time is a function of canister content and orientation. Thirty full canisters of Hurricaine were placed into three equal orientations (upright, inverted, or horizontal). Extrapolating from a full canister, four different estimates of benzocaine residual volume were determined before spraying out the contents (80%, 60%, 40%, and 20% full). Each canister was then sprayed for 10-s intervals, and the quantity delivered was calculated and compared statistically. Upright canisters 100% full emitted more benzocaine than canisters with residual volume 20% full (190 +/- 10 vs 172 +/- 10 mg/s). Inverted canisters emitted significantly less benzocaine from 100% full to residual volume 20% full (188 +/- 14 vs 70 +/- 10 mg/s). Oriented horizontally, two full canisters emitted <76 mg/s benzocaine, contrasted with the remaining eight in that group (186 +/- 20 mg/s). We conclude that the benzocaine (Hurricaine) sprayed in milligrams per second depends on canister content and orientation. When residual volumes diminish, there is a reduction in spraying volume per time. This diminution occurs progressively from larger to smaller residual volumes with canisters oriented horizontally, inverted, or upright. Arbitrary documentation of spraying time bears no relationship to dose delivered. Perhaps affixing an atomization device to a graduated syringe filled with benzocaine will help increase accuracy and precision in dosing.

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.

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.

A complete regional anesthesia technique for cardiac pacemaker insertion.

Sixteen consecutive adult patients scheduled for permanent transvenous cardiac pacemaker insertion received as their total anesthetic the combination of a cervical plexus block and blocks of the second, third, and fourth intercostal nerves using a combination of 1% mepivacaine and 0.2% tetracaine with epinephrine, 1:200,000. This technique consistently provided complete surgical anesthesia of the third cervical (C3) through the fourth thoracic (T4) dermatomes, without anesthesia of the brachial plexus. Anesthesia was adequate for the surgical procedure without the need for supplemental analgesia or anesthesia in all cases. Because fluoroscopy was used routinely for the surgical procedure, it was possible to document that there were no instances of diaphragmatic paralysis or pneumothorax. In contrast to other reports, this technique provides surgical anesthesia that is adequate for all of the approaches used for transvenous pacemaker implantation, except for placement of a battery in an abdominal pouch. There were no serious complications and/or side effects in any of the patients studied.

Brachial plexus block with a new local anaesthetic: 0.5 per cent ropivacaine.

A new local anaesthetic, ropivacaine hydrochloride, was used in a concentration of 0.5 per cent in 32 patients receiving a subclavian perivascular block for upper extremity surgery. One group (n = 15) received 0.5 per cent ropivacaine without epinephrine and a second group (n = 17) received 0.5 per cent ropivacaine with epinephrine in a concentration of 1:200,000. Anaesthesia was achieved in 87 per cent of the patients in both groups in all of the C5 through T1 brachial plexus dermatomes. Motor block was profound with 100 per cent of patients in both groups developing paresis at both the shoulder and hand and 100 per cent developing paralysis at the shoulder. There was a rapid initial onset of sensory block (a mean of less than four minutes for analgesia) with a prolonged duration (a mean of greater than 13 hr of analgesia). The addition of epinephrine did not significantly affect the quality or onset of sensory or motor block. The duration of sensory block was reduced by epinephrine at T1 for analgesia and at C7, C8, and T1 for anaesthesia. The duration of sensory block in the remaining brachial plexus dermatomes as well as the duration of motor block was not effected by epinephrine. There was no evidence of cardiovascular or central nervous system toxicity in either group with a mean dose of 2.5-2.6 mg.kg-1 ropivacaine.