Perivascular Technique Research Articles

A prospective randomized comparison between perivascular and perineural ultrasound guided axillary brachial plexus block for upper limb surgeries

Introduction and Aims: ultrasound had revolutionized the nerve block by, increasing the reliability with less complications. This study evaluates the block characteristics and efficacy between perivascular and perineural ultrasound guided axillary brachial plexus block for upper limb surgeries. Materials and Methods: 100 patients in the age group of 18-60 years belonging to ASA I,II physical status undergoing axillary block in upper limb surgeries were randomly allocated into Group PN- perineural (n=50) and Group PV- perivascular (n=50). In both the groups Musculocutaneous nerve block done with 6ml of local anaesthetic mixture. In perineural group, radial nerve, median nerve and the ulnar nerve were anaesthetized separately with 8ml of local anaesthetic mixture respectively. In perivascular group, the needle tip was then advanced dorsal to the artery, corresponding to 6’o clock position. 24ml of local anaesthetic mixture was incremently injected. The primary objective was to assess the success rate of blockade for surgery. The secondary objectives were to assess the onset and duration of sensory and motor block and to study the incidence of adverse effects. Results: There was no statistical significance in the success rate of blockade between the techniques (PN-98% and PV 96% with P value is 0.362).The sensory and motor onset time in PN group(6.98 min,10.22 min) is faster than PV group(10.96 min,13.50) with P value was Conclusion: we conclude that the USG guided perineural technique as more reliable than the USG guided perivascular technique of axillary block. Keywords: Perivascular, Perineural, Ultrasound guided, Axillary brachial plexus block.

A study to compare the effects of supraclavicular perivascular technique and infraclavicular brachial plexus blockade for below elbow surgeries

A study to compare the effects of supraclavicular perivascular technique and infraclavicular brachial plexus blockade for below elbow surgeries

Inter Scalene Block: Revisiting old technique.

Background and Aims:The technique of percutaneous brachial plexus block has persisted in many variations since first such block given by Hirsheli in 1911.[1] Both supraclavicular and infraclavicular approaches have been described. Consequent to perivascular technique (Winnie and Collins 1964), Winnie described interscalene block (ISB) in 1970.[23] Winnie's was a single deposit block which relied upon volume for its success. It is nearly 50 years that ISB has stood the test of time and has evolved from single to multiple deposits Block. In mid-90s, ultrasound guidance was first explored by anesthetists for regional anesthesia in University of Vienna.[3] As ultrasound guidance is becoming popular and is increasingly available to budding anesthetist, popularity of old technique has started waning. In this study, old technique of ISB was revisited with a view to assess its success rate with established drugs and examine if in light of ultrasound guidance, this technique has become irrelevant for anesthetist today.Methods:A retrospective study, a survey with high response rate, was done on success rate of three variations of old technique of ISB in 100 patients. In variation-1, thirty patients received two deposits of local anesthetic in interscalene groove. In variation-2, thirty patients received four deposits of local anesthetic in interscalene groove. In variation-3, forty patients received six deposits of local anesthetic in interscalene groove along with infiltration of both scalene muscles. In none of the variations, paraesthesia was sought or peripheral nerve stimulator (PNS) or imaging gadget was used. Demographic data in three variations were compared statistically using Chi-square and one-way ANOVA test. Success rate among variations was analyzed by Fisher's exact test.Results:In variation-1, 17 out of 30, in variation-2, 23 out of 30, and in variation-3, 37 out of 40 blocks were successful.Conclusion:Success of ISB given without PNS or ultrasound guidance is directly proportional to the number of deposits of local anesthetic made in interscalene groove.

Randomized prospective study of three different techniques for ultrasound-guided axillary brachial plexus block

IntroductionRandomized prospective study comparing two perivascular techniques with the perineural technique for ultrasound-guided axillary brachial plexus block (US-ABPB). The primary objective was to verify if these perivascular techniques are noninferior to the perineural technique. Method240 patients were randomized to receive the techniques: below the artery (BA), around the artery (AA) or perineural (PN). The anesthetic volume used was 40mL of 0.375% bupivacaine. All patients received a musculocutaneous nerve blockade with 10mL. In BA technique, 30mL were injected below the axillary artery. In AA technique, 7.5mL were injected at 4 points around the artery. In PN technique, the median, ulnar, and radial nerves were anesthetized with 10mL per nerve. ResultsConfidence interval analysis showed that the perivascular techniques studied were not inferior to the perineural technique. The time to perform the blockade was shorter for the BA technique (300.4±78.4s, 396.5±117.1s, 487.6±172.6s, respectively). The PN technique showed a lower latency time (PN – 655.3±348.9s; BA – 1044±389.5s; AA – 932.9±314.5s), and less total time for the procedure (PN – 1132±395.8s; BA – 1346.2±413.4s; AA – 1329.5±344.4s). BA technique had a higher incidence of vascular puncture (BA – 22.5%; AA – 16.3%; PN – 5%). ConclusionThe perivascular techniques are viable alternatives to perineural technique for US-ABPB. There is a higher incidence of vascular puncture associated with the BA technique.

English

INTRODUCTION: Regional anesthesia as the name implies is the blocking of peripheral nerve conduction in a reversible manner by using local anesthetic agents, thereby one region of the body is made insensitive to pain and is devoid of reflex response to surgical stimuli. The central nervous system is spared, so the patient is conscious during the surgical procedure. Regional anesthesia offers many advantages over general anesthesia for surgery on upper extremities, particularly in emergency operations. AIM OF THE STUDY: The aim of the present study is to evaluate the effect of addition of 50μg/kg of preservative free Midazolam to 0.5% Bupivacaine solution in supraclavicular brachial plexus block on the • Onset of blockade, • Duration of blockade, • Intensity of blockade, • Sedation, • Complications if any & • Quality of analgesia. MATERIALS AND METHODOLOGY: Forty adult patients of both sexes in the age group of 20 – 60 years belonging to ASA I / II category and their weight ranging between 50 – 70 kgs, posted for various types of upper limb surgeries at the Department of Plastic Surgery, Institute of Research and Rehabilitation of Hand, Government Stanley Hospital, formed the study group. This study was designed as a prospective, randomized comparative study. After receiving the institutional ethical committee approval and informed consent, the patients were randomly allocated into two groups. Supraclavicular brachial plexus was performed via subclavian perivascular technique. Groups: 1. BM - 20 patients received 30 ml of 0.5% Bupivacaine with preservative free Midazolam 50 μg/kg. 2. B - 20 patients received 30 ml of 0.5% Bupivacaine alone. Inclusion Criteria. 1. ASA I & II. 2. Age group 20 – 60 years. 3. Weight 50 – 70 kilograms. 4. Surgeries of forearm and hand. Exclusion Criteria: 1. Patient refusal. 2. Coagulopathy. 3. Infection at injection site. 4. Pneumothorax or previous pneumonectomy on the opposite side. Patients were all preoperatively evaluated, clinically examined and investigations done prior to assessment. Procedures were explained in detail and written consent obtained. The procedure was carried out in the preparation room or in the theatre were facilities for resuscitation were available. SUMMARY: 1. Onset time for both motor and sensory block was quicker in the Bupivacaine with midazolam group. 2. There was no significant difference between the groups in the time taken for completion of both motor and sensory blockade. 3. There was no difference between the groups in the intensity of blockade. 4. There was no difference between the groups in the mean duration of motor blockade. 5. The mean duration of sensory blockade was significantly prolonged in the Bupivacaine midazolam group. 6. Sedation was statistically significant with Bupivacaine midazolam group in the intraoperative period. 7. There was no complication due to the addition of 50μg/kg Midazolam to Bupivacaine. CONCLUSION: In conclusion, midazolam 50μg/kg when used as an additive to 0.5% Bupivacaine solution for supraclavicular brachial plexus block, quickens the onset of sensory and motor blockade, prolongs the duration of sensory blockade and improves the quality of post operative analgesia with mild intraoperative sedation. Hence, midazolam can be considered as a safe additive to local anaestetic solution for brachial plexus block.

Brachial Plexus Anaesthesia: A Comparative Study on Supraclavicular Subclavian Perivascular Technique with the Axillary Transarterial Technique with A Tourniquet

Objectives : To make a comparative evaluation of efficacy of brachial plexus blockade between supraclavicular subclavian perivascular technique and axillary transarterial technique with a tourniquet and also to compare the latency & potency of the block, to ascertain the risks of complications between the techniques and to compare the haemodynamic stability of the patient.Methods : For this purpose a total of 100 undergoing surgery for distal to the midarm. They were randomly selected by odd and even numbering method. These patients were divided into two groups (Group A: subclavian perivascular supraclavicular technique bearing all the odds numbers and Group B: transarterial axillary technique with a tourniquet bearing all the even numbers; fifty patients in each group.Results : The only exception is the mean on set time of sensory block was 11.0±2.6 minutes and 14.3±2.1 minutes in Group A and Group B respectively. The mean on set time of motor block were 18.3±3.9 minutes in Group A and 21.4±3.2 minutes in Group B. So the mean on set time of sensory block and motor block were statistically significant (p<0.05). Most of the patients found complete sensory block and complete motor block between two groups and no significant (p>0.05) difference was found in the present study. Adequate efficacy of block were predominate in both groups and no significant (p>0.05) difference was found. The level of satisfaction of surgeon and it was found that 92.0% in Group A and 94.0% in Group B were satisfied. Patient’s co-operation was found 92.0% and 94.0% in Group A and Group B respectively. No significant (p>0.05) difference were found in terms of surgeon satisfaction and patients cooperation between two groups.Conclusion : It can be concluded that the supraclavicular subclavian perivascular technique and axillary transarterial technique with a tourniquet both are equally effective and safe method for providing brachial plexus block distal to midarm (Lower half of the arm, elbow, forearm and hand).Chatt Maa Shi Hosp Med Coll J; Vol.14 (2); Jul 2015; Page 21-26

Subclavian Perivascular Technique of Brachial Plexus Anaesthesia

Various approaches to brachial plexus block have been described. Among the supraclavicular approaches even the procedure itself varies. With earlier techniques the exact site for insertion of needle was determined using visual topographic landmarks (1cm above the midpoint of clavicle) 1 whereas with more recent technique, palpable landmarks( the scalene muscle and the interscalene groove) have been utilised 2 . In our study the subclavian perivascular technique of brachial plexus block was conducted in a tertiary level hospital. It was prospective non randomized open level study from 2011 to 2013 which includes 66 patients of both sexes between the age group of 20 to 50 years (ASA grading 1 and 2 patients) undergoing elective upper limb surgeries. The onset and duration of sensory and motor block, need for supplement anaesthesia were observed. Success and complication rate were calculated in percentage. Average onset and duration of sensory and motor block was calculated as mean ±SD and percentage out of 66 patients, 60 patients ( 90.90%) have got successful block with no significant complications

A Prospective, Randomized Comparison Between Double-, Triple-, and Quadruple-Injection Ultrasound-Guided Axillary Brachial Plexus Block

This prospective, randomized, observer-blinded study compared double-, triple-, and quadruple-injection ultrasound (US)-guided axillary brachial plexus block (AXB) for upper-extremity surgery. One hundred twenty patients were randomly allocated to receive a double- (n = 40), triple- (n = 40), or quadruple-injection (n = 40) US-guided AXB. The local anesthetic agent (lidocaine 1.5% with epinephrine 5 μg/mL) and total volume (35 mL) were identical in all subjects. For all 3 groups, the musculocutaneous nerve was identified and anesthetized first. Subsequently, a perivascular technique was performed. Lidocaine was deposited at the 6-o'clock position of the axillary artery for the 2-injection group. For the 3- and 4-injection groups, injections were carried out at the 12-/6-o'clock and 2-/10-/6-o'clock positions, respectively. During the performance of the block, the performance time, number of needle passes, and complications (vascular puncture, paresthesia) were recorded. Subsequently, a blinded observer assessed the onset time, block-related pain scores, and success rate (surgical anesthesia). The main outcome variable was the total anesthesia-related time (sum of performance and onset times). No differences were observed among the 3 groups in terms of total anesthesia-related time (29.2-31.4 mins), success rate (90.0%-97.5%), block-related pain scores, vascular puncture, and paresthesia. Compared with its 3- and 4-injection counterparts, the double-injection technique required fewer needle passes (4.0 ± 1.6 vs 5.2-6.0 ± 1.7-2.8; both P ≤ 0.001). Double-, triple-, and quadruple-injection US-guided perivascular AXB result in comparable success rates and total anesthesia-related times. Because it requires fewer needle passes, the double-injection technique provides a simple alternative for US-guided AXB.

Perineural Infusion of Local Anesthetics

Perineural Infusion of Local Anesthetics

Comparison of continuous 3-in-1 and fascia Iliaca compartment blocks for postoperative analgesia: feasibility, catheter migration, distribution of sensory block, and analgesic efficacy

Background and Objectives: Efficacy and technical aspects of continuous 3-in-1 and fascia iliaca compartment blocks were compared. Methods: Forty-four patients scheduled for cruciate ligament repair or femur surgery were randomly divided into 2 groups. After surgery with the patient anesthetized, catheters were placed for continuous 3-in-1 blocks by means of a nerve stimulator (group 1). In group 2, the catheter was inserted for continuous fascia iliaca compartment block without the use of a nerve stimulator. In both groups, a 5-mg/kg bolus of 0.5% ropivacaine was administered followed by continuous infusion of 0.1 mL/kg/h of 0.2% ropivacaine for 48 hours. In the postoperative period, all the patients received parenteral propacetamol (6 g daily) and ketoprofen (200 mg daily) and 0.1 mg/kg of subcutaneous morphine as rescue analgesia if the visual analog scale (VAS) pain values were greater than 30 mm. We evaluated the technical difficulties relative to catheter placement, the location of the catheter, the analgesic efficacy, and the distribution of the sensory block at 1 hour, 24 hours, and 48 hours. Results: Catheter placement was faster in group 2, and the absence of nerve stimulation decreased material costs ( P < .05). No significant difference was observed between groups concerning location of the catheter tip under the fascia iliaca. In both groups, the distribution of the sensory block and its course were similar except for those of the obturator nerve (more sensory blocks in group 1, P < .05). No significant difference was noted between the groups regarding median VAS pain values and consumption of morphine during the 48-hour period. No major side effect was observed. Conclusions: The authors conclude that a catheter for continuous lumbar plexus block can be placed more quickly and at lesser cost using the fascia iliaca technique than the perivascular technique with equivalent postoperative analgesic efficacy.

Fentanyl improves analgesia but prolongs the onset of axillary brachial plexus block by peripheral mechanism. (Sapporo Medical University, School of Medicine, Sapporo, Japan) Anesth Analg 2000;91:384–387.

This double‐blinded study evaluated the effects of fentanyl added to lidocaine for axillary brachial plexus block in 66 adult patients scheduled for elective hand and forearm surgery. All patients received 40 mL of 1.5% lidocaine with 1:200,000 epinephrine, injected into the brachial plexus sheath using the axillary perivascular technique, and they were randomized into 3 groups. Group 1 was given lidocaine containing 2 mL of normal saline plus 2 mL of normal saline IV. Patients in Group 2 received lidocaine containing 100 μg fentanyl plus 2 mL of normal saline IV. Group 3 patients received lidocaine containing 2 mL of normal saline plus 100 μg fentanyl IV. Sensory and motor blockade were evaluated by using a pinprick technique and by measuring the gripping force, respectively. The success rate of sensory blockade for radial and musculocutaneous nerves and the duration of the sensory blockade significantly increased in Group 2 (323 ± 96 min) as compared with Group 1 (250 ± 79 min). However, the onset time of analgesia was prolonged in every nerve distribution by adding fentanyl to the brachial plexus block. IV fentanyl had no effect on the success rate, onset, or duration of the blockade. Conclude that the addition of fentanyl to lidocaine causes an improved success rate of the sensory blockade, but a delayed onset of analgesia, although this may be accounted for by the decreased pH caused by the fentanyl.Comment by Alan Kaye, M.D. The addition of opioids to regional blocks is controversial. This is due in part to the potential uptake and distribution centrally of the opioid agent. In 66 patients undergoing axillary block, all had 40 mL of 1.5% lidocaine with epinephrine. One group had normal saline, another group has fentanyl plus saline, and a third had just fentanyl. The authors found that the addition of fentanyl caused an improved success rate with regard to sensory blockade. However, onset of the blockade was delayed with fentanyl and this was theorized by a decreased pH caused by the fentanyl. More studies are needed to better elucidate mechanistic effects of opioids and other agents in enhancing or modulating local anesthetics in regional blockade.

Fentanyl Improves Analgesia but Prolongs the Onset of Axillary Brachial Plexus Block by Peripheral Mechanism

We evaluated the effects of fentanyl added to lidocaine for axillary brachial plexus block in 66 adult patients scheduled for elective hand and forearm surgery. In this double-blinded study, all patients received 40 mL of 1.5% lidocaine with 1:200,000 epinephrine, injected into the brachial plexus sheath using the axillary perivascular technique, and they were randomized into three groups. Group 1 was given lidocaine containing 2 mL of normal saline plus 2 mL of normal saline IV. Patients in Group 2 received lidocaine containing 100 μg fentanyl plus 2 mL of normal saline IV. Group 3 patients received lidocaine containing 2 mL of normal saline plus 100 μg fentanyl IV. Sensory and motor blockade were evaluated by using a pinprick technique and by measuring the gripping force, respectively. The success rate of sensory blockade for radial and musculocutaneous nerves and the duration of the sensory blockade significantly increased in Group 2 (323 ± 96 min) as compared with Group 1 (250 ± 79 min). However, onset time of analgesia was prolonged in every nerve distribution by adding fentanyl to brachial plexus block. IV fentanyl had no effect on the success rate, onset, or duration of blockade. We conclude that the addition of fentanyl to lidocaine causes an improved success rate of sensory blockade but a delayed onset of analgesia, although this may be accounted for by the decreased pH caused by the fentanyl. Implications It is still unclear whether the addition of a peripheral opioid is useful for nerve blockade in humans. Peripheral application of fentanyl to lidocaine for axillary brachial plexus blockade in this study provided an improved success rate of sensory blockade and prolonged duration.

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.

Atlas of Regional Anesthesia, Second Edition.

Associate Professor of AnesthesiologyWake Forest University School of MedicineMedical Center BoulevardWinston-Salem, North Carolina 27157–1009Atlas of Regional Anesthesia, Second Edition. By David L. Brown, M.D. Philadelphia, WB Saunders Company, 1999. Pages: 376. Price:$125.00.The second edition of this comprehensive regional anesthesia atlas has been updated and expanded. Dr. Brown has achieved his goal of using clear, simple images to describe the three-dimensional anatomy and approach needed to successfully perform a variety of nerve blocks. The use of color, magnetic resonance imaging, and cross-sectional anatomy with trademark “pane-of-glass” views make the art work very effective, and the shading and clarity of many of the diagrams have been enhanced in this edition. The atlas is organized first by regional anatomy, and then each block is described by perspective (indications, patient selection, drug choice), placement (anatomy, position, problems), and pearls (tips from the author's experience.) As in the first edition, one often has to flip pages to find figures referenced in the text, but this is a result of the number of large figures relative to text.The chapters on brachial plexus block are thorough and well-illustrated, and this is clearly (and not surprisingly) today's best reference for infraclavicular and “plumb-bob” supraclavicular approaches. A bit more detail regarding needle angle to skin and recommended volumes of local anesthetic would be helpful.Lower extremity peripheral blockade is gaining popularity, and the chapters regarding femoral, lateral femoral cutaneous, obturator, and sciatic block are beautifully illustrated and detailed. The sections about lumbar plexus and popliteal block need expansion, however. Injection of air before psoas block is outdated, and the fascia iliaca block goes unmentioned. The lateral approach to popliteal block and sciatic block at the level of the ischial tuberosity would be useful additions.The chapters regarding head and neck, airway, and somatic and sympathetic blocks of the trunk are excellent and essentially unchanged in this edition. Although concern for local anesthetic toxicity is mentioned frequently, recommended maximum dosages for various blocks are not.New chapters in the second edition include infraclavicular, facet, sacroiliac, and superior hypogastric block, with the last three added for particular benefit to clinicians in pain management. The epidural section is substantially expanded, with superb detail of thoracic and cervical approaches.There is further updating with the mention of continuous peripheral blockade (brachial plexus and femoral) and the question of subarachnoid lidocaine “neurotoxicity.” The author's bias against single-shot perivascular techniques is apparent, and some would take umbrage (again) at the statement that those who recommend the use of nerve stimulators do more to impede than to advance regional anesthesia. Those criticisms aside, I recommend this atlas to residents and experienced clinicians who consider regional anesthesia to be a significant part of their practice. The price is average at $125, and the improvements make this edition even more valuable than the first to help make regional anesthesia “work.”

The subclavian perivascular block

The subclavian perivascular technique, introduced by Winnie and Collins in 1964, is one of the most popular supraclavicular approaches to the brachial plexus. It is based on an anatomical concept, the existence of a fibrous tissue sheath surrounding the neurovascular bundle. This sheath acts as a barrier, limiting the diffusion of the local anesthetic away from the nerves. Thus, a single injection of an adequate volume of local anesthetic within this space is able to reach the components of the plexus, consistently producing good results. Different methods are employed to identify the presence of the needle inside the sheath. A fascial “click”, used by some, is a subjective sensation felt by the operator when the needle pierces the fascia. More popular is the technique of eliciting paresthesias. It requires physical contact between needle and nerve, as well as the patient's cooperation to qualify and locate the response. The possibility of increased risk of nerve damage has been raised with this technique. Lately, nerve stimulators have enjoyed increased popularity. They have the theoretical advantage of helping to bring the needle close enough to the nerve to ensure intrafascial injection, without the need for physical contact. The subclavian perivascular block, performed with a nerve stimulator, makes an already good technique even better.

Transarterial axillary brachial plexus block (four-in-one upper extremity block)

A transarterial, perivascular technique for producing axillary brachial plexus block is described. Mepivacaine 1.5%, 50 mL is used. Critical elements for high degree of success (99%) are discussed. Complications are rarely observed.

Supraclavicular approaches to brachial plexus anesthesia

The concept of a continuous perineural and perivascular space surrounding the brachial plexus from roots to terminal nerves simplifies conduction anesthesia of the upper extremity. As with peridural techniques, the space may be entered at any level, and following the injection of a local anesthetic, the extent of anesthesia will depend on the volume of anesthetic and the level at which it is injected. The single injection techniques based on this concept have resulted in both an increased incidence of success and a decreased incidence of serious complications as compared to the multiple injection techniques used previously. The space above the clavicle, the interscalene space, is potentially just such a space; and it is only after the injection of a local anesthetic that it expands to become a true, fluid-filled compartment. Furthermore, this space is quite extensive in its vertical and horizontal axes but very narrow in its anteroposterior axis. It was for this reason that the original subclavian perivascular and interscalene techniques both called for the needle to be introduced in one of the long axes of the space, whereas the more recently introduced parascalene techniques all call for the needle to be inserted in the very narrow anteroposterior axis. As a result, the chance of the needle leaving the space during the performance of the block is minimized with the subclavian perivascular and interscalene techniques, whereas with the parascalene techniques the slightest movement of even the properly placed needle may cause it to leave the space, resulting in the injection of local anesthetic outside of the fascial compartment. In short, the subclavian perivascular and interscalene techniques of brachial plexus block can provide simple, safe, and effective anesthesia for all types of surgery on the upper extremity and shoulder.

Infraclavicular approaches to brachial plexus anesthesia

The infraclavicular approach to the brachial plexus was reintroduced in 1973. The technique described differed from previous infraclavicular techniques in that the needle was introduced more medially from the place of entry and was directed laterally. The author reasons that needle penetration to any depth would be safe and always outside of the thoracic cavity if directed in that fashion. Thus, with this technique, there is practically no danger of pneumothorax, an obvious advantage over supraclavicular and previously described infraclavicular techniques. Furthermore, with this technique the local anesthetic solution is deposited inside the brachial plexus sheath above the level of the formation of the musculocutaneous and axillary nerves, an apparent advantage over the axillary perivascular techniques. The author also points out two additional advantages of his technique: (1) the ulnar segment of the medial cord is readily blocked, which is an advantage over the interscalene technique; and (2) the intercostobrachial nerve is also blocked consistently. The infraclavicular approach also provides larger skin surface area to introduce the needle from and place the catheter, for prolonged analgesia, than other approaches to brachial plexus. Hence, the infraclavicular technique has some appealing theoretical advantages.

Cold Saline Is More Effective Than Room Temperature Saline in Inducing Paresthesia During Axillary Block

Confirmation of the perivascular position of the needle by the injection of cold saline may be helpful to the perivascular technique, since the elicitation of a paresthesia indicates the correct positioning of the needle.In this prospective, randomized study of 48 patients, we found a 100% incidence of successful block with saline at 8-11 degrees C compared to 75% in a control group with saline at room temperature. The paresthesia induced by cold saline appears to be due to thermic stimulation and not to mechanical nerve compression by the saline entering the axillary space. A more frequent rate of correct positioning of the needle was found in the group with cold saline. (Anesth Analg 1995;81:329-31)

CLINICAL AND RADIOLOGICAL COMPARISON OF PERIVASCULAR AND TRANSARTERIAL TECHNIQUES OF AXILLARY BRACHIAL PLEXUS BLOCK

The perivascular technique of axillary brachial plexus block results in incomplete block of radial and musculocutaneous nerves in 10-20% of patients. With the transarterial technique and a large dose of mepivacaine, success rates of 99% have been reported. We have compared the clinical efficacy of these techniques in 50 patients using 1% mepivacaine 45 ml with adrenaline. If required, the block was supplemented with additional blocks of single nerves or i.v. alfentanil. Additionally, eight patients in each group were studied with computed tomography after contrast medium was added to 0.5% bupivacaine 40 ml. There were no statistically significant differences in sensory or motor block between the groups at 20 min or in the plasma concentrations of mepivacaine measured 0-45 min after injection. In the CT scans, both proximal and distal spread of the contrast medium were more common after perivascular than after transarterial block. The distribution of the contrast medium was not related to the efficacy of the block.