mL Of Local Anesthetic Solution Research Articles

A reliable septum exists between the lateral cord and medial and posterior cords in the costoclavicular region: Clinical and microanatomical considerations in brachial plexus anesthetic blockade.

The ultrasound-guided proximal infraclavicular costoclavicular block (PICB) appears popular but its results are inconsistent. We sought an accurate demonstration of septae formed between the brachial plexus cords. We performed in-plane, lateral-to-medial PICBs on 120 patients and recorded images. Once the most superficial lateral cord component was entered, a 0.4-0.6 mA current was applied to confirm needle placement; 5 ml of local anesthetic (LA) solution was then injected and its spread was observed and recorded. As the needle was advanced, the presence or absence of a hyperechoic linear structure was noted before the deeper compartment was reached, specifically looking for the possible displacement of such a septum. Upon initial scanning, a septum was observed in 67 of the 120 patients (46.2%). However, there was clear displacement of a linear septum between the lateral cord compartment and the medial and posterior cord compartments that prevented spread between the compartments in 94.16% of patients. Piercing the septum evoked motor responses from the medial or posterior cord. The same anatomical regions were studied microanatomically by analyzing cross-sections obtained with the same approach angle as the ultrasound probe. Intraplexus fascial septae that bundled the medial and posterior cords into one compartment and separated them from the lateral cord were demonstrated and confirmed microanatomically. This suggests the need for two separate injections (or two separate catheter placements for continuous peripheral nerve blockade) into the superficial and deep compartments to ensure LA spread around all three cords of the brachial plexus at this level.

Evaluation of two different dosages of local anesthetic solution used for ultrasound-guided femoral nerve block for pain relief and positioning for central neuraxial block in patients of fracture neck of the femur

Introduction: Surgical management of the fracture femur is preferred so as to prevent complications associated with prolonged immobilization. Central neuraxial blockade (CNB) is an attractive option for these patients, and an optimal positioning of the patient is a definite requirement. Owing to the pain associated with movement of the fractured limb, it becomes difficult for the patients to give suitable positioning. Femoral nerve block (FNB) features as a rescue analgesia so as to provide adequate analgesia for facilitation of satisfactory positioning. Aim: This study aims to compare analgesic effect of two different dosages of local anesthetic (LA) solution administered for ultrasonography (USG)-guided FNB given to facilitate optimal positioning for conduct of CNB. Materials and Methods: After taking permission from the institutional review board, eighty patients were enrolled in the study to find out the efficacy of dosage of LA solution for FNB in providing pain relief caused by movement of fractured limb during conduct of regional anesthesia. Informed consent was taken. All patients were given USG-guided FNB. Patients were randomized using a computer-generated random number table, into two groups of forty patients each. Group A patients received USG-guided 12 ml of LA solution containing 10 ml lignocaine solution without preservative (2%) plus 2 ml normal saline (NS), while Group B patients received USG-guided 15 ml of LA solution containing 13 ml lignocaine solution without preservative (2%) plus 2 ml NS for positioning before combined spinal epidural. Results: A total of eighty patients, divided randomly into two groups, were enrolled in the study. Demographics (age, sex, weight, and American Society of Anesthesiologists grades) were similar in both groups. No statistical significance was found in the numeric rating scale scores at baseline, zero minutes, 5, and 15 min in both the groups. Conclusion: USG-guided FNB with 12 ml of LA solution was as effective as 15 ml of LA solution for achieving adequate pain relief so as to give optimal positioning for CNB in patients of fracture neck of femur.

Evaluation of clonidine as an adjuvant to brachial plexus block and its comparison with tramadol.

Background and Aims:It has been reported that clonidine when used as an additive in a dose of 90 μg in adults increases the duration of peripheral nerve blocks. Hence, this study was conducted to evaluate the effect of clonidine in brachial plexus blocks and to compare it with tramadol.Material and Methods:Ninety patients posted for upper limb orthopedic surgery were divided randomly into three groups. 40 mL of local anesthetic solution was prepared using 15 mL of 2% lignocaine-adrenaline-sodium bicarbonate solution, 15 mL of 0.5% bupivacaine, and 10 mL distilled water. Patients received a supraclavicular brachial plexus block with 0.7 mL/kg of this solution to which either 1 mg/kg tramadol, 1 μg/kg clonidine, or 1.5 μg/kg clonidine was added. The onset and duration of sensory and motor block and the duration of postoperative analgesia were recorded. Pulse rate, blood pressure, respiratory rate, saturation, sedation, and any side effect were monitored. Results were statistically analyzed using analysis of variance F-test and unpaired t-test.Results:There was a statistically significant difference in the onset of both the sensory and motor components of the block with the fastest onset seen when clonidine was used in a dose of 1.5 μg/kg. The block also lasted statistically significantly longer with clonidine as compared with tramadol although there was no statistically significant increase in the duration of the block when a higher dose of clonidine was used. The time for rescue analgesia was the longest in patients who received 1.5 μg/kg of clonidine (491.8 ± 33.9 min). This duration was also statistically significant. Patients who received tramadol reported a statistically significant higher incidence of nausea.Conclusion:Clonidine in a dose of 1.5 μg/kg body weight provided the fastest onset of sensory as well as motor block and the longest duration of postoperative analgesia and thus is a good additive to local anesthetic solutions for brachial plexus blocks.

The Importance of the Trigeminal Cardiac Reflex in Rhinoplasty Surgery

Trigeminocardiac reflex (TCR) consists of bradycardia or asystole along with hypotension and apnea coinciding with stimulation of the trigeminal nerve. During rhinoplasty procedures, we noticed that local anesthetic solution (LAS) application to the columellar area results in bradycardia. We planned to conduct a randomized prospective study on 47 patients undergoing rhinoplasty to demonstrate the characteristics of TCR arising from the columella. Local anesthetic solution containing 2% prilocaine with 1:80,000 adrenaline was applied under standard general anesthesia protocol. In group 1 (study group, n = 24), 2 mL of LAS was applied to the columella. In group 2 (control group, n = 23), 2 mL of LAS was applied to the nasal dorsum. In group 3 (control group, n = 20), after LAS was applied to nasal dorsum in group 2, we waited for 10 minutes. Then, 2 mL of LAS was applied to the columella. Here, recordings were taken for the columella.Heart rate (HR) and blood pressure (BP) were recorded just before needle insertion (baseline level), at the time of needle insertion (NIT) to the columella or dorsum, and after the 1st, 5th, 10th, 30th, and 60th seconds. Transient bradycardia (≥20% drop in HR) was observed in 33% of the patients in group 1.Decrease in HR compared to the baseline level in group 1 was significantly greater than that of groups 2 and 3 at all times (P ≤ 0.05).Systolic BP in NIT and in 60th second in group 1, only in NIT in group 2 was significantly lower than that of baseline levels (P ≤ 0.05). We concluded that stimulation of a sensory branch of the trigeminal nerve in the columellar area leads to TCR under general anesthesia by eliciting clinical hypotension with a drop in systolic BP and in HR of more than 20% compared to the baseline level.Knowing the existence of a certain TCR area will be helpful to the surgeon and anesthesiologist to exercise extra vigilance and to make continuous and meticulous monitoring of the electrocardiogram, HR, and BP during which the TCR may be precipitated such as local anesthetic infiltration to the columellar area in rhinoseptoplasty operations.

Omoigui Diffusion Technique of Intercostal Nerve Block

This paper describes the relevant anatomy and rationale behind our Diffusion Technique for intercostal nerve block. Using the Diffusion Technique developed by Omoigui, the left middle and index fingers are placed to stabilize the superior and inferior borders of the rib, at a site proximal to the area of pain. A 3 cm, 25 gauge, short-beveled needle is inserted directly onto the midpoint of the rib and 1-3 ml of local anesthetic solution is injected over the rib. There is no attempt to walk off the lower border of the rib and there is no advancement of the needle into the subcostal groove. There is minimal to no risk of any accidental pleural puncture as compared with the Bonica technique. The Omoigui diffusion technique utilizes the spread and diffusion characteristics of the injected local anesthetic to produce blockade of the cutaneous branches and intercostal nerves. This diffusion technique has showed similar therapeutic results as the standard approach. We include a series of cases that responded successfully to this simple diffusion technique for intercostal nerve block.

Avoiding Subarachnoid or Intravascular Injection of Local Anesthetics

Avoiding Subarachnoid or Intravascular Injection of Local Anesthetics

Effect of pressure-reducing devices on the quality of anterior orbit anesthesia

Needle length is an important consideration in the safe conduct of ophthalmic blocks. A shorter needle could be used to insert the local anesthetic before the globe equator in the anterior orbit and to direct the injectable posteriorly using Honan's balloon to produce the desired effect. However, the use of pressure-reducing devices is not advisable in procedures with impaired retinal blood flow. The aim of this work was to demonstrate the effect of ocular compression with a Honan's balloon on the quality of peribulbar anesthesia when a short needle was used. The blockades were performed in 120 patients using a 27 G, half-inch-long needle. The needle was inserted into the inferotemporal quadrant adherent to the inferior orbital notch. The 7 to 10 ml of local anesthetic solution, consisting of bupivacaine 0.5%, lidocaine 2% in a ratio of 3:2 with hyaluronidase 5 U/ml, was injected followed by application of Honan's balloon or no compression. Ocular akinesia was assessed 10 min later; if inadequate, supplementary anesthesia was provided. No difference was detected in terms of volume injected, supplementation, and akinesia score. Under the conditions of this study, Honan's balloon did not contribute to the quality of the anterior orbit anesthesia, and the technique can be successfully used when ocular compression is contraindicated.

The effect on outcome of peribulbar anaesthesia in conjunction with general anesthesia for vitreoretinal surgery

The purpose of this study was to evaluate peri-operative outcome after vitreoretinal surgery when peribulbar anaesthesia is combined with general anaesthesia. Sixty adult patients undergoing elective primary retinal detachment surgery with scleral buckling or an encircling procedure received either peribulbar anaesthesia in conjunction with general anaesthesia or general anaesthesia alone. For peribulbar anaesthesia a single percutaneous injection of 5-7 ml of local anaesthetic solution (0.75% ropivacaine with hyaluronidase 15 iu.ml(-1)) was used. The incidence of intra-operative oculocardiac reflex and surgical bleeding interfering with the surgical field, postoperative pain and analgesia requirements, and postoperative nausea and vomiting were recorded. In the block group there was a lower incidence of oculocardiac reflex and surgical bleeding intra-operatively. Patients in the block group also had better postoperative analgesia and a lower incidence of postoperative nausea and vomiting compared with the group without a block. The use of peribulbar anaesthesia in conjunction with general anesthesia was superior to general anaesthesia alone for vitreoretinal surgery with scleral buckling.

A Contraindication to Using Local Anesthetic Solution for Expanding the Epidural Space

In Response: We thank Mahajan et al. (1) for their interest in our study (2). Epidural anesthesia after dural puncture does raise concern about the possibility of profound levels of spinal anesthesia from leakage of the epidurally administered local anesthetic through the dural hole into the subarachnoid space. There are anecdotal case reports and some studies supporting this concern (3). Bernards et al (4) demonstrated that influx is directly proportional to the size of the dural puncture and inversely proportional to the distance of the dural puncture from the site of epidural drug administration. This concern is particularly relevant for the combined spinal-epidural technique (CSE), because this technique includes an intentional dural puncture and a bolus epidural injection. Indeed, some authors thought that the dural hole created during the CSE technique, without subarachnoid drug administration, might increase subarachnoid transfer of epidurally administered drugs, thus improving the epidural analgesia. However, the clinical significance of these proposed effects during CSE labor analgesia has not been demonstrated (5–7). As for the authors’ case, there are some confusing factors: Their test dose (3 mL of 0.25% [i.e., 7.5 mg] plain lidocaine) was low. According to Moore and Batra (8), the test dose should be at least 45 mg. The rapid onset suggests direct subarachnoid injection. The lack of freely flowing cerebrospinal fluid from the epidural needle does not exclude direct subarachnoid injection. The authors mention injection of 13 mL of local anesthetic solution. In our view, the total dose should be injected in divided doses and slowly. We did not know whether apnea, unconsciousness, and dilated pupils were seen as a result of the action of local anesthetic on the brainstem and how long those symptoms lasted in that case because general anesthesia was administered. We consider the case described by Dr. Mahajan et al. a cautionary note, and not a contraindication. Leakage of epidural local anesthetic through a dural rent must be kept in mind, and perhaps it would be prudent in such a setting to decrease the dose (e.g., by approximately 25%) and be careful to give the dose incrementally, avoiding any injection pressure. Mehmet Cesur Haci A. Alici Ali F. Erdem Fikret Silbir Mustafa S. Yüksek Department of Anesthesiology and Reanimation Medical Faculty Atatürk University Erzurum, Turkey [email protected]

In Defense of the Peripheral Nerve Stimulation Technique

To the Editor: Voelckel et al. (1) recently demonstrated an increased risk of nerve damage when nerve stimulators elicit a motor block at current intensities below 0.2 mA. The minimal current to produce an effective block is unknown. It can be defined as the value below which an appropriate motor response is no longer obtained after a search within the three axes of space (2). A systematic search for the minimum current may reduce the risk of neural injury (3). Jochum et al. (4) showed a correlation between the minimal stimulating current and success rate, but never recommended eliciting a motor response with stimulating current intensities as low as 0.1–0.2 mA. Using a nerve stimulator requires precision and knowledge of its performance characteristics, particularly in the low-current range. The authors chose a relatively long impulse duration of 0.3 ms. Pither et al. (5) pointed out that impulses of short duration provide better discrimination between observed responses. In our view, optimal needle localization should be based on a combination of criteria (4) rather than relying on minimum current intensity alone. These criteria include the minimal current intensity of a defined duration delivered via an unrestrained and immobile needle, the sensation of penetrating the relevant fascia, a clear motor end point, the disappearance of a muscular contraction following the injection of 1 mL of local anesthetic solution, the ease of reproducing this contraction by increasing once more the current intensity, and painless injection without resistance. It is hard to know whether these were taken into account in this experimental study design. It is under these conditions that it will be possible on one hand to further improve the risk–benefit ratio of nerve stimulation, and on the other hand to establish predictors of success that will enhance our practice. Denis Jochum Department of Anesthesiology Private Hospital Group of Center Alsace Colmar, France Gabriella Iohom Department of Anesthesiology Cork University Hospital Cork, Ireland Louis-Jean Dupré Department of Anesthesiology Clinique Cléret Chambéry, France Hervé Bouaziz Department of Anesthesiology University Hospitals Nancy, France [email protected]

A paravenous approach for the saphenous nerve block

Background and Objectives: This study assesses a paravenous approach for saphenous nerve block at approximately the level of the tibial tuberosity, and compares it with the conventional technique of blind subcutaneous infiltration between the tibial tuberosity and the gastrocnemius muscle. Methods: In dissections of 5 cadavers, the saphenous nerve was found very close to the saphenous vein bilaterally. Subsequently, in 20 volunteers, a bilateral saphenous nerve block was performed with 5 mL mepivacaine on each side. Randomly assigned, the block was performed by blind subcutaneous injection using a 23-gauge needle of 2.5 cm on one side and by a paravenous subcutaneous approach on the other. Results: The paravenous approach produced a saphenous nerve block in all 20 volunteers whereas the blind subcutaneous approach was successful in only 6 (33%) (P [lt ] .05). Seven volunteers had a painless minor hematoma at the paravenous site and 2 had a hematoma at the classical site. Conclusion: The saphenous nerve can be blocked effectively by a paravenous approach using only 5 mL of local anesthetic solution. This approach is advantageous because of its easily identifiable landmark. Reg Anesth Pain Med 2001;26:504-506.

A reply

We are grateful to Drs Troy and Kinirons for their interest in our case report and for their comments. The choice of approach to the brachial plexus in a patient who needs elbow surgery, but who has minimal ventilatory reserve, is a difficult one. The incidence of phrenic nerve paralysis approaches 100% with techniques aimed at the upper reaches of the brachial plexus [1], decreasing progressively with techniques that aim at lower portions of the plexus. Anaesthetic efficacy for elbow surgery also varies with different approaches to the brachial plexus, being relatively low with single-injection techniques in the distal axilla, increasing as one approaches a target area between the coracoid process and the first rib, and then decreasing again above this level, as the lower roots and trunks of the plexus are often missed by blocks such as the interscalene or subclavian perivascular. Variations in technique that may encourage local anaesthetic spread to this ‘coraco-costal’ area (the part of the plexus that can provide anaesthesia of the entire upper limb) have been described: distal pressure and high volume with an axillary approach [2, 3], proximal pressure and high volume with an interscalene approach [4]. As an increased volume of injectate will most likely result in an increase in both proximal and distal spread (even with digital pressure [5]), and if it is accepted that the mechanism of phrenic block is the proximal passage of local anaesthetic within the plexus sheath to the cervical roots, logical choices for anaesthesia in the described circumstances include a distal plexus block with a high volume or an accurately placed ‘coraco-costal’ block with a lower volume. The solutions suggested by your correspondents (multiple injection technique at the axilla or a coracoid-level block) are also wholly acceptable. However, the technique used in a particular situation depends not only on the anatomy, the techniques and the patient, it also depends upon the skills and experience of the operator. We were not experienced in coracoid-level blocks and had had unsuccessful experiences of single-shot axillary blocks for elbow surgery in the awake patient. We therefore chose a technique with which we were becoming increasingly familiar and which targeted the appropriate area of the brachial plexus: the vertical infraclavicular block. We chose a volume of 20 ml of local anaesthetic solution for two reasons: firstly, in order to minimise the proximal spread of local anaesthetic, and thus, we hoped, to reduce the chances of phrenic nerve paralysis; second, it is our contention that 20 ml of local anaesthetic is all that is needed to produce arm, as opposed to arm and shoulder, anaesthesia at a plexus level behind or close to the clavicle. This view is supported by Winnie's demonstrations of the relationship between injection volume and extent of anaesthesia in upper limb blocks [6].

Multiple-Injection Axillary Brachial Plexus Block: A Comparison of Two Methods of Nerve Localization–Nerve Stimulation Versus Paresthesia

We conducted this prospective study to compare the onset time and the success rate of a multiple-injection axillary brachial plexus block performed by using two methods of nerve localization: paresthesia elicitation or nerve stimulation. Each of the major nerves of the plexus was located by elicitation of a paresthesia (Group PAR;n = 50) or by nerve stimulation (Group PNS;n = 50) and injected with 10 mL of local anesthetic solution. Time to perform the block, onset time of the primary block, time to achieve readiness for surgery, and total anesthetic time were significantly shorter in Group PNS than in Group PAR. The incidence of complete block was larger in Group PNS than in Group PAR (91% vs 76%;P < 0.05), and this was related to a larger success rate for anesthetizing the radial and the musculocutaneous nerves (P < 0.05). The frequency of venous puncture was larger in Group PAR (P < 0.05). For multiple-injection axillary brachial plexus block, we conclude that nerve stimulation resulted in a greater success rate and a faster onset than paresthesia elicitation, and it should be considered when the radial and musculocutaneous nerve distributions are involved in the surgical area. Implications Two methods of nerve localization were compared when performing an axillary brachial plexus block by the multiple-injection technique. Nerve stimulation provided a faster onset and a greater incidence of complete block, related to a better success rate for anesthetizing the radial and the musculocutaneous nerves, than paresthesia elicitation.

1,001 subclavian perivascular brachial plexus blocks: Success with a nerve stimulator

Among the supraclavicular approaches to the brachial plexus, the subclavian perivascular technique is a well-established method of anesthesia of the upper extremity. Ever since Kulenkampf described his technique, eliciting a paresthesia has been almost mandatory ("no paresthesia, no anesthesia"). Lately, nerve stimulators have become more popular. However, up to the present time, clinical studies involving the nerve stimulator have failed to show success rates comparable to paresthesia techniques. Data from 1,001 consecutive, subclavian perivascular blocks were prospectively gathered over 2.5 years. All blocks were performed according to Winnie's technique, but using a nerve stimulator instead of a paresthesia. When an adequate response was obtained, 35 to 40 mL of local anesthetic solution was injected. Nine hundred seventy-three blocks (97.2%) were completely successful; 16 blocks (1.6%) were incomplete and needed supplementation; and 12 blocks (1.2%) failed and required general anesthesia, giving a success rate for regional anesthesia of 98.8%. The subclavian perivascular block consistently provides an effective block for surgery on the upper extremity. At the site of injection with this technique, the plexus is reduced to its smallest components and the sheath is reduced to its smallest volume, which explains in great part the success obtained with this block. We believe that we have demonstrated a nerve stimulator technique that is both highly successful and safe; no clinical pneumothorax was found nor did any other major complications develop.

Nerve Stimulator and Multiple Injection Technique for Upper and Lower Limb Blockade

To evaluate the failure rate, patient acceptance, effective volumes of local anesthetic solution, and incidence of neurologic complications after peripheral nerve block performed using the multiple injection technique with a nerve stimulator, we prospectively studied 3996 patients undergoing combined sciatic-femoral nerve block (n = 2175), axillary blocks (n = 1650), and interscalene blocks (n = 171). The success rate and mean injected volumes of local anesthetic were: 93% with 22.6 +/- 4.5 mL in the axillary, 94% with 24.5 +/- 5.4 mL in the interscalene, and 93% with 28.1 +/- 4.4 mL in the sciatic-femoral nerve blocks. Patients receiving combined sciatic-femoral nerve block showed more discomfort during block placement and worse acceptance of the anesthetic procedure than patients receiving brachial plexus anesthesia. During the first month after surgery, 69 patients (1.7%) developed neurologic dysfunction on the operated limb. Complete recovery required 4-12 wk in all patients but one, who required 25 wk. The only variable showing significant association with the development of postoperative neurologic dysfunction was the tourniquet inflation pressure (<400 mm Hg compared with >400 mm Hg, odds ratio 2.9, 95% confidence intervals 1.6-5.4; P < 0.001). We conclude that using the multiple injections technique with a nerve stimulator results in a success rate of >90% with a volume of <30 mL of local anesthetic solution and an incidence of transient neurologic complication of <2%. Implications: Based on a prospective evaluation of 3996 consecutive peripheral nerve blocks, the multiple injection technique with nerve stimulator allows for up to 94% successful nerve block with <30 mL of local anesthetic solution. Although the data collection regarding neurologic dysfunction was limited, the withdrawal and redirection of the stimulating needle was not associated with an increased incidence of neurologic complications. Sedation/analgesia should be advocated during block placement to improve patient acceptance. (Anesth Analg 1999;88:847-52)

Relative potencies of bupivacaine and ropivacaine for analgesia in labour

We have used the technique of randomized, double-blind sequential allocation to compare the minimum local analgesic concentrations (MLAC) of epidural bupivacaine and ropivacaine for women in the first stage of labour. The test bolus was 20 ml of local anaesthetic solution. The concentration was determined by the response of the previous woman to a higher or lower concentration of local anaesthetic, according to up-down sequential allocation. Efficacy was assessed using a 100-mm visual analogue pain score (VAPS). The test solution had to achieve a VAPS of 10 mm or less to be judged effective. For bupivacaine, MLAC was 0.093 (95% CI 0.076-0.110)% w/v, and for ropivacaine, 0.156 (95% CI 0.136-0.176)%w/v (P < 0.0001, 95% CI difference 0.036-0.090). The analgesic potency of ropivacaine was 0.60 (0.47-0.75) relative to bupivacaine. Claims for reduced toxicity and motor block must be considered with differences in analgesic potency in mind.

A complication of peribulbar block in a patient with exophthalmos

A patient with marked exophthalmos secondary to thyroid eye disease presented for tarsorrhaphy and removal of orbital fat. A single superolateral peribulbar injection was performed. After injection of 3.5 ml of local anaesthetic solution, the globe suddenly dislocated anteriorly. This complication has not been described previously. In patients with exophthalmos, general anaesthesia should be considered as the method of choice for ophthalmic procedures.

Transarterial brachial plexus anesthesia for hand surgery: A retrospective analysis of 346 cases

Study Objectives: To study the safety and efficacy of the transarterial approach to brachial plexus block with 60 to 70 ml of local anesthetic solution, and to compare the success and complication rates of this block performed by experienced or inexperienced anesthesiologists. Design: Retrospective analysis of 346 records of ASA physical status I–IV patients who underwent elective unilateral orthopedic upper limb surgery with transarterial plexus anesthesia. Setting: University teaching hospital. Measurements and Main Results: Blood pressure (BP) and heart rate were measured at 5-minute intervals. Analgesia was registered as successful, incomplete, or failed. Any patient complaints or adverse reactions were recorded. The first 60 ml of local anesthetic provided surgical analgesia to 64 % of patients. With a supplemental 10 ml of anesthetic, the overall success rate was 94 %, with only 19 of 346 patients requiringgeneral anesthesia. Experience in performing the block increased the success rate from 90% to 98% ( p ⪡ 0.001). Six patients experienced either nausea or a transient BP decrease that did not require medication. There was no record of toxic or other serious adverse reaction. Conclusions: Transarterial brachial plexus block administered with a 60 to 70 ml dose of local anesthetic provides surgical analgesia for hand surgery with an excellent success rate and without serious adverse effects.

Effets in vitro de l'alcalinisation de la bupivacaïne 0,25 % et de la lidocaïne 2 %

Recent clinical studies have suggested that alkalinization of local anaesthetic agents may shorten the onset time and lengthen their duration of action. In clinical practice, sodium bicarbonate 1.4 and 4.2 % are often added to local anaesthetic agents to obtain these effects. We evaluated pH changes of 4 local anaesthetic solutions commonly used for obstetrical epidural anaesthesia, in order to develop titration curves with sodium bicarbonate 1.4 and 4.2 %. Local anaesthetic agents tested included lidocaine 2 % and bupivacaine 0.25 % with and without epinephrine. Each one was divided in 10 mL aliquots, and supplemented with 25 μg of sufentanil (1 mL). The pH measurement were made with a pH-meter P 500 with a combined electrode (TBC 12/HS) in the standard solution and after incremental addition of 0.5 mL of 1.4 or 4.2 % sodium bicarbonate. The percentage of the free form of local anaesthetic was calculated for each step, using the Henderson-Hasselbalch equation. Results showed that alkalinization is not beneficial with epinephrine free solutions. Increasing volumes of sodium bicarbonate, buffered the acidic effect of sodium bisulfite present in solutions containing epinephrine, and increased the percentage of the free form of local anaesthetic to the level of epinephrine free solutions. From this pH point upwards, the gain is poor and precipitates are generated. This study suggests that 1 mL of 4.2 % sodium bicarbonate for 10 mL of local anaesthetic solution is the best theorical choice for alkalinization of a local anaesthetic associated with epinephrine.

A Parascalene Technique of Brachial Plexus Anesthesia

A technique for brachial plexus anesthesia is described consisting of the injection of 20 ml of local anesthetic solution into the lower part of the posterior triangle of the neck at a point 1.5 to 2 cm above the clavicle at the lateral border of the anterior scalene muscle. The technique is simple, safe, and produced satisfactory anesthesia of the entire extremity in 97 of the first 100 cases in which it was used. Side effects and complications were minor and transient.