Elisabeth Van Gessel

Clonidine Combined with a Long Acting Local Anesthetic Does Not Prolong Postoperative Analgesia after Brachial Plexus Block but Does Induce Hemodynamic Changes

Clonidine in brachial plexus block prolongs analgesia of local anesthetics of short and intermediate duration. We performed a prospective randomized double-blinded study to determine the efficacy and adverse effects of clonidine mixed with a long-acting local anesthetic on postoperative analgesia. Sixty adult patients underwent elective rotator cuff repair using interscalene brachial plexus block combined with general anesthesia and were randomly divided into one of the following three groups. Placebo (n = 20): interscalene block with 40 mL of 0.5% bupivacaine with epinephrine (1/200000) and 1 mL of 0.9% saline, completed by 1 mL of 0.9% saline IM in the controlateral shoulder; Control (n = 20): interscalene block with 40 mL of 0.5% bupivacaine with epinephrine and 1 mL of 0.9% saline, completed by 150 &mgr;g (=1 mL) of clonidine IM; Clonidine (n = 20): interscalene block with 40 mL of 0.5% bupivacaine with epinephrine and 150 &mgr;g (=1 mL) of clonidine, completed by 1 mL of 0.9% saline IM. During anesthesia hemodynamic variables and fractional expired isoflurane concentration (FeISO) were recorded. The following postoperative variables were assessed: duration of interscalene block, quality of pain relief on a visual analog scale, side effects, and consumption of morphine with a patient-controlled analgesia device over 48 h. Patient characteristics were comparable. During anesthesia mean arterial pressure, heart rate, and FeISO were significantly decreased in Clonidine and Control groups compared with Placebo group. Duration of analgesia, defined as the time elapsed from interscalene injection to the first morphine request, was 983 ± 489 min in the Placebo, 909 ± 160 min in the Control, and 829 ± 159 min in the Clonidine groups. Pain scores and consumption of morphine at 24 h and 48 h showed no differences among the three groups. We conclude that adding 150 &mgr;g of clonidine in interscalene block does not prolong analgesia induced by 40 mL of bupivacaine 0.5% with epinephrine, but decreases mean arterial blood pressure and heart rate. IMPLICATIONS Clonidine in brachial plexus block does not improve postoperative analgesia when mixed with a long-lasting anesthetic. Nevertheless, with or without clonidine, bupivacaine in interscalene block provides a long-lasting analgesia of approximately 15 h.

Continuous Spinal Anesthesia: Where Do Spinal Catheters Go?

The purpose of this study was to investigate the incidence of technical problems encountered when performing continuous spinal anesthesia and the influence of catheter tip position on block height following injection of a hypobaric spinal anesthetic. Twenty-nine elderly patients undergoing hip surgery were studied. Lumbar puncture was performed with an 18-gauge Tuohy needle at the L3-4 (or L2-3) interspace. Threading was defined as easy if a 20-gauge catheter was inserted on the first try, 3-4 cm cephalad. Threading was considered difficult if cephalad insertion of the catheter was impossible on the first try; the Tuohy needle was then rotated with its bevel facing caudally, the catheter inserted for 1-2 mm, and the needle turned back cephalad together with the catheter partially threaded, for further cephalad insertion up to 4 cm. All patients received 7.5 mg of hypobaric bupivacaine or tetracaine in the lateral decubitus position and sensory levels were determined by pinprick. After surgery all catheters were injected with radiographic dye and examined by radiograph for verification of position. The determination of the level of lumbar puncture was falsely judged in 59% of cases, the puncture being performed 1 or 2 spaces higher than assumed. Although threading difficulties were encountered in 4/28 cases, there was a 100% success rate in catheter insertion. One catheter displacement into the epidural space was noted. Twenty of twenty-eight catheters took a cephalad direction, 6 remained coiled in a horizontal position, and 2 took a caudal direction.(ABSTRACT TRUNCATED AT 250 WORDS)

Postoperative analgesia with “3-in-1” femoral nerve block after prosthetic hip surgery

PurposeTo evaluate the efficacy of a single shot “3-in-1” femoral nerve block for prosthetic hip surgery in association with general anaesthesia on post-operative analgesia.MethodsForty patients, ASA 1 to 3, received sham block or “3-in-1” femoral nerve block, following Winnie’s landmarks with a nerve stimulator, and 40 ml bupivacaine 0.5% with epinephrine were injected after induction of anaesthesia. Vecuronium, 0.1 mg· kg−1, was added after performing the block and anaesthesia was maintained with isoflurane, oxygen 40% and nitrous oxide 60%. Fentanyl, 1.5 μg· kg−1, was administered before incision to all patients. Heart rate, blood pressure, fentanyl requirements and FETiso were measured throughout surgery. During the post-operative period, 75 mg diclofenacim and/or 0.1 mg· kg−1 morphine sc were administered when pain score was > 3/10 and repeated when necessary. Pain scores at first analgesic intervention, at 24 hr and 48 hr as well as diclofenac and morphine requirements after surgery were recorded.ResultsThere was no difference in anaesthetic requirements during surgery. The time from performance of sham or “3-in-1” femoral nerve block to the first analgesic intervention (261 ± 49 min versus 492 ± 40 min,P < 0.05) and time from extubation to the first analgesic intervention (61 ± 44 minvs 298 ± 39 min,P < 0.05) were prolonged in the study group. However, pain scores and the analgesic requirements in the postoperative periods (24 and 48 hr) were similar.ConclusionThere is a short-term benefit during the first few postoperative hours in using a single shot “3-in-1” femoral nerve block to complement general anaesthesia for elective hip surgery.RésuméObjectifÉvaluer l’efficacité du bloc fémoral «3-dans-1 » en une injection pour la chirurgie prosthétique de la hanche associé à une anesthésie générale pour procurer l’analgésie postopératoire.MéthodesQuarante patients, ASA 1 à 3, ont reçu un bloc factice ou un bloc fémoral «3-dans-1 » avec repérage des points de Winnie par stimulateur nerveux et réalisé avec de la bupivacaïne 0,5% adrénalinée 40 ml injectée après l’induction de l’anesthésie. Du vécuronium, 0,1 mg· kg−1, était ajouté après la réalisation du bloc et d’une anesthésie maintenue à l’isoflurane, oxygène 40% et protoxyde d’azote 60%. On administrait 1,5 μg·kg−1 de fentanyl à tous les patients avant l’incision. La fréquence cardiaque, la pression artérielle, les besoins en fentanyl et la PETiso étaient mesurés pendant la chirurgie. À la période postopératoire, les patients recevaient 75 mg de diclofénacim et/ou 0,1 mg· kg−1 de morphine sc lorsque le score dépassait 3 sur l’échelle de 10, au besoin. On enregistrait les scores de douleurs au moment de la première administration d’analgésique, à 24 h et 48 h de même que les doses de diclofénac et de morphine après la chirurgie.RésultatsLes besoins d’anesthésie étaient les mêmes pendant la chirurgie. L’intervalle entre le bloc factice ou le bloc «3-dans-1 » et la première administration d’analgésique (261 ± 49 min vs 492 ± 40 min, P < 0,05) et l’intervalle entre l’extubation et la première administration analgésique (61 ±44 minvs 298 ± 39 min, P < 0,05) se prolongeaient dans le groupe d’étude. Cependant, les scores de douleur et les besoins analgésiques de la période postopératoire (à 24 et 48 h) étaient semblables.ConclusionLe bloc fémoral en une injection «3-dans-1» administré comme complément à l’anesthésie générale procure un avantage à court terme au cours des premières heures qui suivent une intervention chirurgicale non urgente de la hanche.

Anesthetic assessment in an outpatient consultation clinic reduces preoperative anxiety

Purpose: Preoperative anxiety in relation to anesthesia remains for many patients a major subject of concern. The aim of the present study was to compare the level of preoperative anxiety in patients assessed in an outpatient consultation clinic with the anxiety level of those having been assessed by the anesthesiologist after entering the hospital.Method: We studied two groups of 20 patients who underwent elective transurethral prostate or bladder resection: group A having the anesthetic assessment between one-two weeks before hospitalisation, group B having this assessment the evening before surgery, after entering the hospital. Two different methods to assess anxiety were used: the Multiple-Affect-Adjective-Check-List (MAACL) and the visual analogue scale of anxiety (VAS).Results: Both anxiety provided scores, assessed by two different methods, were lower in group A, than in group B (P<0.01).Conclusion: The results of this study confirm that an anesthetic assessment in an outpatient consultation clinic reduces preoperative anxiety, when compared with an assessment on the evening before surgery.RésuméObjectif: L’anxiété préopératoire reste aujourd’hui encore un phénomène mal résolu pour le patient. Le but de la présente étude est de comparer l’impact de deux types de visites préanesthésiques sur l’anxiété préopératoire: l’une, dans une clinique de consultation externe, l’autre, le jour avant l’opération alors que le patient est hospitalisé.Méthode: Deux groupes de 20 patients, dont l’intervention chirurgicale urologique endoscopique avait été planifiée, ont été étudiés. Dans le groupe A, l’évaluation anesthésique a été réalisée une à deux semaines avant l’opération dans une clinique de consultation externe; dans le groupe B, il s’agissait de la visite préanesthésique la veille de l’opération et le patient était déjà hospitalisé. Nous avons utilisé 2 méthodes pour mesurer l’anxiété: un test verbal d’anxiété, selon Zuckermann, et une échelle visuelle analogique.Résultats: Les patients du groupe A ont présenté un score d’anxiété préopératoire significativement plus bas (P<0,01) que ceux du groupe B, et cela selon les 2 méthodes de mesures de l’anxiété utilisées dans notre étude.Conclusion: Les résultats de cette étude confirment qu’une consultation anesthésique externe réalisée une à deux semaines avant l’opération réduit significativement l’anxiété préopératoire du patient, comparée à une visite préanesthésique la veille de l’opération.

Comparison of hypobaric, hyperbaric, and isobaric solutions of bupivacaine during continuous spinal anesthesia

This study was designed to compare the anesthetic properties of hypobaric bupivacaine with those of isobaric and hyperbaric solutions when administered in the supine position in an elderly population undergoing hip surgery using continuous spinal anesthesia. Plain bupivacaine (0.5%) was mixed with equal volumes of 10% dextrose (hyperbaric), 0.9% NaCl (isobaric), or distilled water (hypobaric) to obtain 0.25% solutions. In a double-blind fashion, all patients received 3 mL (7.5 mg) of their particular solution injected through the spinal catheter in the horizontal supine position. The sensory level obtained in the hyperbaric group (median, T4; range, T3-L3) was significantly higher than in both the isobaric (median, Til; range, T6-L1) and hypobaric (median, LI; range, T4-L3) groups. A motor blockade of grade 2 or 3 was obtained in 14 of 15 and 12 of 15 patients in, respectively, the hyperbaric and isobaric groups, but only in 8 of 15 patients in the hypobaric group.After the initial injection of 3 mL (7.5 mg), a sensory level of T10 and a motor blockade of grade 2 or 3 was obtained in 14 of 15, 5 of 15, and 3 of 15 patients in the hyperbaric, isobaric, and hypobaric groups, respectively. All remaining patients received 1 or 2 additional milliliters (2.5–5 mg) and achieved these required anesthetic conditions, except for one patient in the hyperbaric group and eight patients in the hypobaric group in whom anesthesia was achieved with hyperbaric tetracaine. The decrease in mean arterial pressure was significantly more severe in the hyperbaric (30%) than in either the isobaric (18%) or hypobaric (14%) groups. The authors conclude that isobaric bupivacaine used during continuous spinal anesthesia in the supine horizontal position produces a suitable and more “controllable” anesthesia for surgical treatment of fractured hips in geriatric patients. Under similar conditions, hyperbaric bupivacaine produces major hemodynamic consequences with high cephalad spread and hypobaric bupivacaine has too high an incidence of failure.

Epinephrine Does Not Prolong the Analgesia of 20 ml Ropivacaine 0.5% or 0.2% in a Femoral Three-in-one Block

We tested the effect of epinephrine added to 20 mL ropivacaine 0.5% and 0.2% on postoperative analgesia via a femoral catheter after total knee replacement. Forty-one patients undergoing total knee replacement under combined peripheral block/general anesthesia were randomly allocated to two groups. After insertion of a femoral catheter, 21 patients in the Ropivacaine-Epinephrine (ROPI-EPI) group received 20 mL ropivacaine 0.5% plus epinephrine 1:200,000, whereas 20 patients in the Ropivacaine group (ROPI) received 20 mL plain ropivacaine 0.5%. Thereafter, a sciatic block with 30 mL bupivacaine 0.5% plus epinephrine 1:200,000 was performed in all patients, followed by general anesthesia. After surgery, patient-controlled analgesia (PCA) with ropivacaine 0.2% plus epinephrine 1:200,000 for Group ROPI-EPI and plain ropivacaine 0.2% for Group ROPI was available via the femoral catheter (200 mL ropivacaine 0.2% ± epinephrine, bolus 20 mL, lockout 120 min). The patients were instructed to use PCA when the knee pain score was >3 cm. The interval between the initial ropivacaine injection and the first PCA injection determined the duration of 20 mL ropivacaine 0.5% ± epinephrine, whereas the interval between the first and second PCA injection determined the duration of 20 mL ropivacaine 0.2% ± epinephrine. The average duration of ropivacaine 0.5% was 657 ± 345 min for the ROPI-EPI group and 718 ± 423 min for the ROPI group (NS), whereas for ropivacaine 0.2%, the average duration was 409 ± 245 min for the ROPI-EPI group and 419 ± 339 min for the ROPI group (not significant). We conclude that epinephrine does not influence the duration of analgesia of the ropivacaine concentrations investigated.

Cerebrospinal Fluid Density Influences Extent of Plain Bupivacaine Spinal Anesthesia

Background The attempts to explain the unpredictability of extent of spinal block provided by plain local anesthetic solutions have resulted in many clinical reports; however, causes of this uncertainty are as yet unknown. Recently, normal values of the human cerebrospinal fluid densities have been studied showing important interindividual variations, especially between females and males. The current study was designed to evaluate as primary endpoint the influence of cerebrospinal fluid density values on the extent of spinal block with plain bupivacaine. The ancillary endpoints were search of factors explaining the interindividual differences in cerebrospinal fluid density values reported and determination of the relation between upper extent and regression of spinal anesthesia. Methods Sixty-four consecutive patients undergoing peripheral orthopedic surgery with spinal block were enrolled. Spinal anesthesia was performed in the lateral decubitus position with the operated side upward. Two milliliters of cerebrospinal fluid was sampled before injection of 3 ml plain bupivacaine 0.5%. The patient was immediately turned supine and remained in the horizontal position until the end of the study. Maximal sensory block level and time to sensory regression to L4 were determined for each patient enrolled. Cerebrospinal fluid and bupivacaine densities as well as cerebrospinal proteins, glucose, sodium, and chloride concentrations were measured. Results A highly significant correlation between cerebrospinal fluid density and maximal sensory block level was found (P = 0.0004). However, this correlation was poorly predictive (R2 = 0.37). Cerebrospinal fluid density, proteins, and glucose concentrations were significantly higher in men than in women: 1.000567 ± 0.000091 versus 1.000501 ± 0.000109 g/ml (P = 0.014), 0.46 ± 0.18 versus 0.32 ± 0.13 g/l (P = 0.001), and 3.27 ± 0.7 versus 2.93 ± 0.5 mm (P = 0.023), respectively. A highly significant (P = 0.0004) and predictive (R2 = 0.73) inverse correlation was found between maximal upper sensory extent and sensory regression to L4. Conclusion These findings indicate an influence of cerebrospinal fluid density on subarachnoid distribution of 3 ml plain bupivacaine 0.5% and show that with higher cerebrospinal fluid densities, a higher spinal block level can be expected.

Flumazenil antagonizes the central effects of zolpidem, an imidazopyridine hypnotic

Zolpidem is a new imidazopyridine‐hypnotic that selectively binds to the central ω1‐receptor subtype. A double‐blind, randomized, three‐way, crossover placebo‐controlled study was carried out in nine healthy male volunteers to assess the possible antagonism of central nervous system–depressant effects of Zolpidem by flumazenil. Subjects received Zolpidem (0.21 mg/kg) or placebo, intravenously, followed 17 minutes later by flumazenil (0.04 mg/kg) or placebo. Vigilance and performance were assessed by a trained anesthetist with use of ciliary reflex, response to a verbal instruction, subjective sedation, a tracking task, and a free recall task. Zolpidem produced a clinically relevant hypnotic effect in five subjects and significantly impaired performance in all nine subjects up to 90 minutes after dosing. Flumazenil rapidly antagonized clinical sedation in the five subjects who were asleep and significantly reversed the performance decrement within 3 minutes, without any escape phenomenon. Flumazenil did not change Zolpidem plasma concentrations, confirming the pharmacodynamic nature of the interaction. Flumazenil may thus be a safe and effective antidote in patients with Zolpidem overdosage.

Effect on postoperative analgesia of small-dose lysine acetylsalicylate added to prilocaine during intravenous regional anesthesia

Nonsteroidal antiinflammatory drugs act largely peripherally by blocking the local synthesis of prostaglandins.The aim of this study was to evaluate whether the addition of a small dose of lysine acetylsalicylate (LA) to the prilocaine used for intravenous regional anesthesia (IVRA) would improve the quality of postoperative analgesia. Sixty patients undergoing lower extremity IVRA for foot or ankle surgery were randomly assigned to three double-blind groups: LA-IVRA where 90 mg of LA was mixed with prilocaine 0.5% for IVRA and 1 mL of 0.9% NaCl administered intravenously (IV) through the forearm catheter after tourniquet inflation; LA-IV where 1 mL of 0.9% NaCl was mixed with prilocaine and 90 mg of LA administered IV; and placebo where 1 mL of 0.9% NaCl was administered both with prilocaine for the IVRA and IV. Duration of analgesia (time elapsed between tourniquet release and first injection of morphine, expressed as mean +/- SD) was significantly longer (P < 0.05) in LA-IVRA (387 +/- 216 min) when compared with LA-IV (175 +/- 264 min) and placebo (126 +/- 201 min). Analgesic requirements remained significantly lower in LA-IVRA when compared with placebo only during the first six postoperative hours, LA-IV being in an intermediate position. Pain scores were significantly lower in LA-IVRA during the first postoperative hour when compared with LA-IV and during the first 3 postoperative hours when compared with placebo. We conclude that 90 mg of LA (corresponding to 50 mg of acetylsalicylic acid) added to prilocaine 0.5% during IVRA improves the quality of postoperative analgesia in the early postoperative period. (Anesth Analg 1997;84:1081-5)

The effects of solution concentration and epinephrine on lateral distribution of hyperbaric tetracaine spinal anesthesia

In a search of a differential spinal block between dependent and nondependent sides, we investigated whether the use of a larger concentration of hyperbaric tetracaine (T) and/or the omission of epinephrine (E) would provide differential spread in patients left for 15 min in the lateral decubitus position.Spinal anesthesia was performed in the lateral decubitus position with the operated side dependent in 60 patients scheduled for lower limb surgery. All patients remained lateral for 15 min after spinal injection before being turned supine. They received 12 mg of T in 10% dextrose and E 0.2 mg was added when predicted duration of surgery was more than 90 min. The concentration of T to be used for each patient was randomized. This resulted in four groups of 15 patients: T 0.5% + E (control group), T 1% + E, T 0.5%, and T 1%. A unilateral anesthesia was defined as the presence of an adequate sensory (L-1 or higher) and/or motor (3 degrees) blockade on the dependent side and the absence of one or both modalities on the nondependent side, or as a duration of sensory (regression to L-2) and motor (1 degrees of recovery) blockade 20% longer on the dependent compared to the nondependent side. None of the 60 patients showed unilateral sensory block. A comparable number of patients in all groups showed unilateral motor block: four in T 0.5% + E, two in T 1% + E, four in T 0.5%, and five in T 1%. Likewise, a comparable number of patients in all groups showed a prolonged duration of sensory and motor block, respectively: six and eight in T 0.5% + E, six and nine in T 1% + E, six and eight in T 0.5%, and seven and seven in T 1%. In conclusion, although a preferential distribution of hyperbaric T toward the dependent side in patients of all four groups was noticed, the use of a larger concentration of T, omission of E, or combination of these two factors did not provide a more marked differential spread when compared to the standard solution of T 0.5% + E. (Anesth Analg 1996;83:755-9)