Regional Anesthesia Syllabus V1.7

7/22/2019 Regional Anesthesia Syllabus V1.7

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Regional Anesthesia for Arm, Wrist and Hand Surgery

Learning Objectives:

1. Describe the indications and contraindications for the various approaches to the brachial plexus appropriate for arm, wrist and hand surgery

2. Describe the relevant anatomy of the brachial plexus3. Describe the techniques, local anesthetics and adjuvants used for performing a

block of the brachial plexus for arm, wrist and hand surgery


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inje te inside the bundle. The arm is abducted to 9O, as in theaxillary approach, excluding all the cases in which it is notpossible to do it. Finally, due to the needle being directedlaterally, the spread of the injected solution is directed laterally,If the tip of the needle is lateral to the coracoid process, themajority of the injected solution may therefore miss themusculocutaneous and axillary nerves and this technique maysimulate an axillary block that is performed higher in theaxillary perivascular compartment.

In I977 Sims suggested new landmarks in the effort toovercome some of the disadvantages of Rajs technique, makingthe infraclavicular BPB easier (also in obese patients) and usinga shorter needle. The landmarks are the inferior border of theclavicle and the coracoid process of the scapula. The indexfinger should be placed in the groove between these twostructures; advancing medially and inferiorly, it will fall into adepression within the superior portion of the major pectoralismuscle (inferiorly and medially), the coracoid process of thescapula (laterally), and the clavicle (superiorly). A 40-mmneedle is introduced at this point and advanced inferiorly,laterally, and posteriorly toward the apex of the axilla. Usually,the plexus is located 2 to 3 cm beneath the skin.

In 1981, Whiffler proposed the coracoid block in whichthe injection site is not far from that proposed by Sims, but thetechnique of injection is completely different. The patient liessupine with the head turned away from the arm to be blocked;the shoulder is depressed and the arm abducted to 45 from thechest wall. Once the coracoid process is identified, it is possibleto estimate the depth of the injection by palpating with theindex finger the axillary arterial pulse as high as possible in theaxilla, and placing the thumb of the same hand on the anterior surface of the chest wall over the site at which the index finger

palpates the artery This point usually lies in the deltopectoralgroove. The needle is inserted with a right angle to the skin, ona line marked between the point in which the subclavian artery

pulsation disappears under the clavicle and the projection onthe anterior surface of the chest wall of the axillary arterial

pulsation, just inferiorly and medially to the coracoid process,to the depth estimated as indicated above. After an initialinjection of I2 mL of local anesthetic, the needle is withdrawn1 cm and a second similar injection is made (in muscular individuals a third injection of 12 mL is required after withdrawing the needle 1 more centimeter). This techniquedoes not require the use of an ENS because the objective is notto make an injection inside the neurovascular sheath but to laydown a wall of anesthesia through which the plexus must pass.

Anatomy

The brachial plexus is formed by the union of the anterior primary divisions of 0 C6, C7, C8, and Tl spinal nerves withfrequent contribution of C4 and T2.12,13 It starts from thevertebral column, runs in the groove between the anterior andthe middle scalene muscles, passes between the clavicle andthe first rib where it is joined by the subclavian artery, Lvhichruns deep to the anterior scalene muscle, and proceeding-under the pectoralis minor muscle insertion on the coracoid

process enters the upper limb in the axilla. In its course fromthe intervertebral foramina to the arm the plexus is composedconsecutively of roots, trunks, divisions, cords, and terminalnerves, formed through a complex process of combining anddividing.

After leaving the intervertebral foramina, the roots of thefifth, sixth, seventh , and eighth cervical nerves pass behind thvertebral artery and travel laterally in the gutters formed by thesuperior surfaces of the anterior and posterior tubercles of thecorresponding cervical transverse processes. At the distal endof the transverse processes the roots descend in front of themiddle scalene muscle toward the first rib, above which theyfuse with the root of the first thoracic nerve, which passesupward and laterally in front of the neck of the first rib and

behind the pleura over the apex of the lung, to form the threetrunks of the plexus. In its passage from the cervical transverse

processes to the first rib, the plexus, first as roots and then astrunks, is sandwiched between the anterior and middle scalenemuscles and so invested by the fascia of those muscles thatlimit the interscalene space. It is really the fascia covering thescalene muscles, derived from the prevertebral fascia, whichconstitutes the sheath of the brachial plexus.

As the three trunks, named superior (formed by the union ofCS, C6 roots), middle (C7), and inferior (C8, Tl), crossfirst rib they are arranged one on top of the other vertically, asthe name implies, and are joined inside the sheath by thesubclavian artery to form the subclavian perivascular space.

Not infrequently, the inferior trunk of the brachial plexus getstrapped behind, and even under the artery, which could make a

barrier to the diffusion of local anesthetic solution injectedhigher in the interscalene space.

After the trunks have passed over the first rib and under theclavicle, at about the upper border of the clavicle, each trunk divides into an anterior and posterior division. As the plexusemerges from under the midpoint of the clavicle in theinfraclavicular region of the axilla, the fibers of the sixdivisions recombine to form the three cords of the plexus:medial, lateral, and posterior. They are surrounded by the fourwalls limiting the axilla: pectoralis major and minor muscles

form the anterior; the subscapularis, teres major, and lamus dorsi muscles complete the posterior wall; the medial wailis made by the first four ribs of the chest wall; and the lateralwall is formed by the medial side of humerus head and byglenoid process of the scapula. In passing under the clavicle,the subclavian artery becomes the axillary artery and liescentral to the three cords that are not really medial, lateral, and

posterior to the axillary artery until they pass behind the pectoralis minor muscle. Within this space the cords graduallyrotate around the artery until, in the second portion of theartery, their position become truly medial, lateral, and poste-rior to the artery. As it passes over the first rib and under theclavicle, the subclavian Irein, in becoming the axillary ve

joins the neurovascular bundle that takes name of axifascia, (extension of the prevertebral fascia). l4

It is approximately at the lateral edge of the pectoralis minor muscle that the cords divide into the major terminal nervesThe lateral and medial cords give off as their branches thalateral and medial heads of the median nerve and thenmedial cord continues as the ulnar nerve and the lateral cord a:the musculocutaneous nerve; the posterior cord gives offaxillary nerve as major branch and then continues as the radianerve. Only the median, radial, ulnar, and medial antebraccutaneous (a medial cord secondary branch) nerves with

brachial artery and vein lie within the axillary sheath atlevel at which the axillaq block is performed. It isimportant to emphasize that the musculocutaneous, thelary, and the medial brachial cutaneous nerves are not


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1 0 .

11.

the nerve fibers there will be an immediate loss of prcyiously observed muscle movements. If not, the needlemay have been pushed through the nerve and it should bewithdrawn slightly. If acute pain is elicited by the injec-tion, the needle could have been advanced inside the nerveand it should be withdrawn immediately.,4fter careful aspiration, the volume of local anestheticsolution is injected at that site. The needle may then be

removed from the patient.After the deposition of the anesthetic solution in theinfraclavicular region, anesthesia develops from the topdown in 10 to 30 minutes (onset time depending on theanesthetic solution). The extent of anesthesia is from thehand to the medium part of the humerus, including thesensitive area supplied by the musculocutaneaus nerve.There is not involvement of the phrenic nerve. As for theaxillary approach to the brachial plexus, the shoulder andthe clavicle are not involved in the block.

Drugs Volume and Dosage

The neurovascular bundle in the infraclavicular region is verycompliant, thus it is possible to inject a large volume of anesthetic solution: 30 to 40 (depending on the patient

body weight). A contrast medium injected inside the brachial plexus sheath in the infraclavicular region is observed sprcad-ing from the axilla to the inferior border of the clavicle (Fig 2).

The anesthetic solutions used are: mepivacaine 1.5S (30 to40 mL, max 600 mg). bupivacaine 0.25% to 0.5% (30 to 40 ml.,max 150 mg), or ropivacainc 0.5% lo 0.75% (30 to 40 mL, max225 mg).

Indications

The infraclavicular brachial plexus block is indicated for thesurgery of the hand, forearm, and elbow. This approach is alsovery effective for postoperative or emergency analgesia andideal for long-term catheter placement (Fig 3), more cffcctivethan the axillary approach in which the movement anddislocation of the catheter are easier and the infectious risk increased.

It is also indicated for all the conditions in which the axillary block is difficult to perform: shoulder ankylosis or stiffness,upper limb fractures, previous lymphadcnectomy of the axilla,and scars or local infection, because it is possible to perform itwith the arm adducted.

Fig 3. This approach is ideal for catheterization, especiallywhen a long period of analgesia is required, as for rehabilita-tion of posttraumatic ankylosis of the elbow in children.

Another important advantage of the infraclavicular approach is the large analgesia extent, comprehending also thearea supplied by the musculocutaneous and axillary nerves, sothe patient can better tolerate the placement of a tourniquet atthe proximal extremity of the arm. The performance of the

block is easy and safe because the r isk of pneumothorax is justtheoretical and it can not provoke paralysis of the phrenicnerve.*

Moreover, patient comfort is optimal, even in the case of humeral fracture and in young people. Psycl~ologically, patients tolerate this kind of approach better than the axillary or the intcrscalene. Furthermore the risk of infection is very lov

In obese patients, because of the difficulty to identify thelandmarks, localization of the correct site of injection may be

more difficult.

Complications and Limitations

Our modified technique appears safe and rarely complicated. Nevertheless, an anesthetist experienced in regional anesthesiatechnique is necessary If the site of puncture and the directionof the needle are correct the worst complication, pneumotho-rax, will be avoided. Moreover, there is no involvement of the

phrenic ncrvve, thus no danger of respiratory function impair-ment. Vascular puncture (Fig 4) and, eventually, hematom

Fig 4. Vascular puncture is a possible complication of theinfrarlauirlllar annrnnrh ri~w to the lame size o f v e s s e l s .


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R EGIONAL A NESTHESIA AND P AIN M EDICINES ECTION E DITOR

D ENISE J. W EDEL

A Magnetic Resonance Imaging Study of Modifications to the Infraclavicular Brachial Plexus Block ivind Klaastad, MD*, Finn G. Lilles, MD, Jan S. Rtnes, MD, PhD,Harald Breivik, MD, PhD, and Erik Fosse, MD, PhD*Department of Anesthesiology, The National Hospital Orthopedic Centre; and The Interventional Centre andDepartment of Anesthesiology, The National Hospital, Oslo, Norway

A previously described infraclavicular brachial plexus block may be modified by using a more lateral needleinsertionpoint,while thepatient abducts thearm 45or90. In performing the modified block on patients ab-

ducting 45, we often hadproblemsfinding thecords of the brachial plexus. Therefore, we designed an ana-tomic study to describe the ability of the recommendedneedle direction to consistently reach the cords. Addi-tionally, we assessed the risk of penetrating the pleura by the needle. Magnetic resonance images were ob-tained in 10 volunteers. From these images, a virtualreality model of each volunteer was created, allowingprecise positioning of a simulated needle according to

the modified block, without exposing the volunteers toactual needle placement. In both armpositions, the rec-ommended needle angle of 45 to the skin was too shal-low to reach a defined target on the cords. Comparing

the two arm positions, target precision and risk of con-tacting thepleura were more favorable with thegreaterarm abduction. We conclude that when the arm is ab-ducted to 90, a 65-needle angle to the skin appearsoptimal for contacting the cords, still with a minimalriskofpenetratingthepleura.However,thisneedstobeconfirmed by a clinical study.

(Anesth Analg 2000;91:92933)

Infraclavicular brachial plexus blocks aim at thecords of the brachial plexus and have been de-signed to obtain complete nerve block of the upper

extremity while minimizing the risk of pneumothorax(16). In a previous magnetic resonance (MR) study of the infraclavicular block described by Raj et al. (Rajs block) (1), we proposed a more lateral needle inser-tion point (7). This would bring the needle closer tothe cords and farther away from the pleura.

Our group had been introduced to such a modifi-cation of Rajs block during a workshop at a meetingin 1993. Regrettably, this method has not been pub-lished. We will refer to it as the lateral approach.According to our recollection, it was performed as

follows (Figs. 1, 2B, 3B): The supine patient abductsthe arm to 45. Two arterial points are palpated andmarked where the subclavian artery dips under thesuperior border of the clavicle (alternatively at the base of the interscalene cleft) and approximatelywhere the brachial artery crosses the lateral border of the pectoralis major. A line between these points is

drawn. The needle insertion point is on this line, at aradial distance of 2.5 cm from the lines intersection withthe inferior border of the clavicle. The needle is directedlaterally along the line while kept at an angle of 45 to theskin. A nerve stimulator aids in exact positioning of theneedle.

The lateral approach may also be performed withthe patient abducting the arm 90 (workshop 1996, SanDiego). This position brings the needle insertion pointmore cephalad and the needle course more lateralthan with lesser degrees of abduction. Theoretically,this should reduce the risk of pneumothorax. Thisvariant has not been published.

The lateral approach differs from Rajs block onlyregarding the point of needle insertion (Fig. 1). Byusing Rajs block, the patient abducts the arm, prefer-ably to 90. The needle insertion point is 2.5 cm belowthe inferior border of the clavicle, on a paramedianline through the point at which the subclavian arteryis palpated dipping under the clavicle, or on a para-median line through the midpoint of the clavicle.

During the first 28 months after the 1993 meeting,we have tried the lateral approach in 161 patients withthe arm abducted to 45. Frequently, we had to redi-rect the needle to find the nerves, and in 18 patients(11%), we finally discontinued the method. No pa-tients demonstrated clinical signs of pneumothorax.

Supported by the National Hospital Orthopedic Centre.Accepted for publication April 10, 2000.Address correspondence and reprint requests to Dr. . Klaastad,

The National Hospital Orthopedic Centre, Department of Anesthe-siology, Trondheimsveien 132, 0570 Oslo, Norway.

2000 by the International Anesthesia Research Society0003-2999/00 Anesth Analg 2000;91:92933 929


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Because of the difficulties with the technique, wequestioned if the recommended needle angle to the

skin guides the needle close enough to the cords andtherefore initiated the present study.The primary aim of this anatomical study was to

investigate the ability of the lateral approach to reachthe brachial plexus by using a variety of needle anglesto the skin. Additionally, we wanted to confirm theclinical impression of a decreased risk of pneumotho-rax. We were also interested in comparing the resultsof the method with the arm abducted 45 and 90. Forthe study, we used MR imaging because it easilydemonstrates the brachial plexus (5,79).

MethodsThe protocol, approved by the regional ethical commit-tee, was similar to our first study and used the same10 healthy volunteers (7). A needle was never inserted inthe volunteers. MR images were taken with arm abduc-tion at 45 and 90, and a virtual reality model of eachvolunteers infraclavicular region was created.

In the model, the needle insertion point was deter-mined after marking the position of two anteroposte-rior lines in the coronal (frontal) plane (Fig. 2B). Thefirst line abutted the superior border of the clavicleand went through the midaxis of the subclavian ar-

tery. The second line went through the junction of the

brachial artery (its midaxis) and the lateral edge of thepectoralis major muscle. The plane between these an-teroposterior lines was the first of two planes definingthe recommended needle direction (the needle trajec-tory). A third anteroposterior line was determined in

this plane, 2.5 cm from the inferior border of theclavicle. The point at which this line hit the chestsurface defined the needle insertion point.

The target was determined as in our first study:Through the point at which the perpendicular linefrom the most anterocaudad point of the coracoidprocess hit the first plane defining the needle trajec-tory, a sagittal (paramedian) plane was constructed.The middle point of all nerve structures around theartery in this plane defined the target.

The second plane, defining the needle trajectory, wasperpendicular to the axial (transverse) plane (Fig. 3B),went through the needle insertion point, and had a 45medial angle to the coronal plane. The final position of the needle point was defined as where the needle trajec-tory hit the sagittal plane through the target.

The needle trajectorys distance from the target wasmeasured in coronal and axial planes. From thesemeasurements, the true distance between the trajec-tory and the target was calculated and could be con-trolled by direct measurements in the sagittal planethrough the target. The needle angle to the skin con-tacting the target was measured in the axial plane.Needle depths to the target and the final position of the needle point were calculated after measurements

in axial and coronal planes. The trajectorys relation tothe pleura was analyzed in the axial plane through thesimulated needle insertion site, measuring the needleangle to touch the pleura.

The results are presented as mean sd or mean(range). Students paired t -test was used to assessdifferences of the lateral approach by 90 and 45 armabduction. Probability values 0.05 were consideredsignificant.

ResultsThe volunteers, five women and five men, were 309 (2451) yr old with a height of 175 11 (160193) cmand a weight of 68 16 (50102) kg.

The deviation of the simulated needle trajectoryfrom the target was great, approximately 2 cm, with both 45 and 90 abduction of the arm (Table 1). In both arm positions, the needle angle to the skin (in theaxial plane) necessary to contact the target was prac-tically identical (mean, 68 and 67) and considerablygreater than the 45-needle angle recommended. Theprecision was much better in the coronal than in theaxial plane, particularly with 90 abduction, having a

near 100% precision.

Figure 1. Front view of infraclavicular anatomy, right side, arm 90abducted (Volunteer 1). Merging segmented magnetic resonance

images with a correlated surface picture of the identical personcreated the picture. The hand-held white and black needles dem-onstrate point of needle insertion and needle direction by using thelateral approach for infraclavicular brachial plexus block and theinfraclavicular brachial plexus block described by Raj et al. (1),respectively. The subclavian/axillary artery (white) is not marked, but is located cephalad to the corresponding vein (V). The cords(gray), not marked, surround the artery longitudinally. Only partsof the pectoralis major muscle (pma, dark) and the pectoralis minormuscle (pmi, gray) are presented, caudad to the axillary vein. clclavicle, C1 first costa, C2 second costa, cp coracoid process,c.hu caput humeri.

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The needle depths were similar in both arm posi-tions, approximately 4 cm when the simulated needlecontacted the target.

The needle angle to the skin necessary to touch thepleura was great in both arm positions, never 80,and distinctly greater with 90 arm abduction thanwith 45 abduction. With 90 arm abduction, alsowhen applying the optimal needle angle to contact thetarget, the sector between the needle and the pleurawas considerable, 39 (2854).

DiscussionThe present noninvasive MR study of the lateral ap-proach for infraclavicular brachial plexus block dem-onstrates that the deviation of the recommended nee-dle direction from the target on the cords was greatwith both 45 and 90 arm abduction, mostly because

the needle angle to the skin was too shallow. This

probably explains the difficulties we had locating the brachial plexus in patients.

In both arm positions, the risk of contacting thepleura appeared minimal, confirming our clinical im-pression. An approximate doubling of the recom-mended 45 needle angle to the skin was required forthe simulated needle to touch the pleura.

We consider the lateral approach more favorablewith 90 arm abduction than 45 because the needletrajectory was more precise in reaching the cordsand had a larger gap to the pleura in the formerposition.

With 90 arm abduction, the precision can be en-hanced by increasing the needle angle to the skin from45 to 65. One might prefer starting with an angle of 40 and, when necessary, increasing it in steps of 10 toa maximum of 80. The risk of penetrating the pleura

would remain small within this angle range, provided

Figure 2. A, Coronal magnetic resonance image, right side, arm 90 abducted (Volunteer 1). B, Drawing based on the coronal image in A.Right infraclavicular region, arm 90 abducted (Volunteer 1). Illustrations of the lateral approach for infraclavicular brachial plexus block inthe coronal plane. Added to the figure are the complete projection of the clavicle (cl) and a large part of the lateral border of the pectoralismajor muscle (pma). In the lower half of the picture is part of the right lung (pu). The artery (A) is depicted in its complete length, whereasonly a shorter distal part of the corresponding vein (V) is seen, caudad to the artery. Part of the brachial plexus (pl) is marked black cephaladto the artery. The recommended needle direction (the needle trajectory) is defined by two planes, of which the first goes through A 1 and A 2 ,perpendicular on the coronal plane. In this volunteer, the needle trajectory did not deviate from the target in the coronal plane. Therefore,the final position of the needle point is identical to the position of the target, and the corrective angle to bring the needle point to the targetis zero, in the coronal plane. The target on the cords is defined periarterially in the sagittal plane (not marked) through the point at whichthe perpendicular line from the most anterocaudad point of the coracoid process hit the first plane defining the needle trajectory. Theposterior projection of the perpendicular line is indicated. cp coracoid process, ac acromion, c.hu caput humeri, I* the posteriorprojection of the needle insertion point, T* the anteroposterior projection of the target, A 1 an anteroposterior line through the point atwhich the subclavian artery would have been palpated at the superior edge of the clavicle, A 2 an anteroposterior line through the pointat which the brachial artery would have been palpated at the lateral border of the pectoralis major muscle.

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that the other details of the technique and the config-uration of the thoracic cage are recognized.

The selection of our target on the cords may be con-troversial. With a more proximal target on the cords, theneedle angle to the skin necessary to hit this target

would increase, increasing the risk of contacting the

pleura. A more distal target would reduce this angle, butcould end in an area more easily reached by an axillaryapproach (10). Taken together, we think that our chosentarget is appropriate.

In conclusion, our MR study demonstrates that the

45-needle angle to the skin recommended by the

Table 1. Proximity of the Needle Trajectory to the Target and to the Pleura

Target deviation (mm) Target angleNeedle depth

(mm) Pleura anglePleura-target

angle

Coronal a Axial b Sagittal Axial Before After Axial Axial

Mean 45 abduction 8 3 21 8 24 7 68 7 24 8 41 8 91 6 23 5Mean 90 abduction 3 3 18 6 19 6 67 10 25 8 38 5 106 5 39 7Range 45 abduction 313 1036 1338 5577 1342 3053 8198 1630Range 90 abduction 07 529 529 4177 1843 3351 95114 2854P 0.033* 0.239 0.042* 0.814 0.731 0.076 0.001* 0.001*

Target deviation the distance in mm between the needle trajectory and the target, as seen in three different planes; the true deviation/distance is found inthe sagittal plane through the target, Target angle the needle angle to the skin to touch the target (the optimal angle to the skin), in the axial plane throughthe point of needle insertion, Needle depth (mm)/Before and After the needle depth before and after redefining the optimal angle to the skin, Pleura anglethe needle angle to the skin to touch the pleura, in the axial plane through the point of needle insertion, Pleura-Target angle the angle difference between the

described pleura and target angles.a With 45 abduction of the arm, the simulated needle trajectory was caudad to the target in all volunteers. With 90 abduction, the trajectory was cephaladto or corresponding to the target in all volunteers except for Volunteer 3. He had a 1-mm caudad deviation of the simulated needle from the target.

b With 45 abduction of the arm, the needle trajectory was anterior to the target in all volunteers. With 90 abduction, the trajectory was anterior to the targetin all volunteers except for Volunteer 3. He had a 5-mm posterior deviation of the needle from the target.

* Significant difference between the results in the two arm positions by using Students paired t -test, when P 0.05.

Figure 3. A, Axial magnetic resonance image, right side, arm 90 abducted. Image through the point of needle insertion (Volunteer 1). B,Drawing based on the axial image in A, through the point of needle insertion (I). Right infraclavicular area, arm 90 abducted. Illustrationsof the lateral approach for infraclavicular brachial plexus block in the axial plane. Through I, four lines are drawn, marked by the numbers1, 2, 3, and 4. 1 the tangent to the skin, 2 the recommended 45 medial needle angle to the skin, 3 the needle angle to the skin necessaryto contact the target; in this volunteer 74 and 4 the needle angle to the skin necessary to touch the pleura, 102 in this volunteer. Therecommended needle direction (the needle trajectory) is defined by two planes, of which the second goes through Line 2, perpendicular tothe axial plane. The angle difference between Lines 3 and 2 represents the deviation of the needle trajectory from the target, 74 45 29in this volunteer. The angle between Lines 4 and 3 is the medial deviation of the simulated needle contacting the target necessary to touchthe pleura, in this volunteer 102 74 28. Ant anterior, Post posterior, T* cephalad projection of the study defined target at thelevel of the cords, I-T* is the projection of the recommended needle direction (the needle trajectory) to the axial plane through I, F* cephaladprojection of the final position of the needle point, pl cords of the brachial plexus, A and V cross sections of the artery and vein,respectively, pma the pectoralis major muscle, pmi the pectoralis minor muscle, pu the right lung, bro the right main bronchus,sc scapula, cl clavicle, C1 cross section of first costa, C2 cross section of second costa.

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lateral approach of the infraclavicular brachial plexus block is often too shallow to contact the cords of the brachial plexus, with both 45 and 90 arm abduction.By using 90 abduction, a 65-needle angle to the skinappears optimal, still with a minimal risk of penetrat-

ing the pleura. However, this needs to be confirmed by a clinical study.

For better understanding of the brachial plexus anatomy, parallel toour MRI studies, we performed human cadaver dissections on the brachial plexus. We thank Professor Per Brodal, at the Departmentof Anatomy, University for Oslo for encouraging discussions andcooperation by the dissections. We thank Terje Tillung (The Inter-ventional Center) for processing the images and Per yvind Hvid-sten (The Norwegian Defense Research Establishment) for develop-ing the three-dimensional visualization software.

References1. Raj PP, Montgomery SJ, Nettles D, Jenkins MT. Infraclavicular

brachial plexus block: a new approach. Anesth Analg 1973;52:897903.

2. Sims JK. A modification of landmarks for infraclavicular ap-proach to brachial plexus block. Anesth Analg 1977;56:5545.

3. Whiffler K. Coracoid block: a safe and easy technique. Br JAnaesth. 1981;53:8458.

4. Kilka HG, Geiger P, Mehrkens HH. Die vertikale infraklaviku-lare blockade des plexus brachialis. Anaesthesist 1995;44:33944.

5. Wilson JL, Brown DL, Wong GY, et al. Infraclavicular brachialplexus block: parasagittal anatomy important to the coracoidtechnique. Anesth Analg 1998;87:8703.

6. Salazar CH, Espinosa W. Infraclavicular brachial plexus block:variation in approach and results in 360 cases. Reg Anesth PainMed 1999;24:4116.

7. Klaastad , Lilles FG, Rtnes JS, et al. Magnetic resonanceimaging demonstrates lack of precision in needle placement bythe infraclavicular brachial plexus block described by Raj et al.[letter]. Anesth Analg 1999;88:5938.

8. Posniak HV, Olson MC, Dudiak CM, et al. MR imaging of the brachial plexus. AJR Am J Roentgenol 1993;161:3739.

9. Brown DL, Cahill DR, Bridenbaugh LD. Supraclavicular nerve block: anatomic analysis of a method to prevent pneumothorax.Anesth Analg 1993;76:530 4.

10. Winnie AP. Guest discussion. Anesth Analg 1973;52:9034.

ANESTH ANALG REGIONAL ANESTHESIA AND PAIN MEDICINE KLAASTAD ET AL. 9332000;91:92933 MRI AND INFRACLAVICULAR BRACHIAL PLEXUS BLOCKS


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1998 by International Anesthesia Research Society.

Volume 87(4) October 1998 pp 870-873

Infraclavicular Brachial Plexus Block: Parasagittal AnatomyImportant to the Coracoid Technique

[Regional Anesthesia And Pain Management]

Wilson, Jack L. MD; Brown, David L. MD; Wong, Gilbert Y. MD; Ehman, Richard L.MD; Cahill, Donald R. PhD

Departments of (Wilson, Brown, Wong) Anesthesiology, (Ehman) Radiology, and (Cahill) Anatomy, Mayo

Clinic, Rochester, Minnesota.Accepted for publication July 15, 1998.Address correspondence and reprint requests to J. L. Wilson, MD, Department of Anesthesiology, Mayo Clinic,200 First St. SW, Rochester, MN 55906.

Abstract

Infraclavicular brachial plexus block is a technique well suited to prolonged continuouscatheter use.We used a coracoid approach to this block to create an easily understoodtechnique. We reviewed the magnetic resonance images of the brachial plexus from 20male and 20 female patients. Using scout films, the parasagittal section 2 cm medial to

the coracoid process was identified. Along this oblique section, we located a pointapproximately 2 cm caudad to the coracoid process on the skin of the anterior chest wall.From this point, we determined simulated needle direction to contact the neurovascular

bundle and measured depth. At the skin entry site, the direct posterior insertion of aneedle will make contact with the cords of the brachial plexus where they surround thesecond part of the axillary artery in all images. The mean (range) distance (depth alongthe needle shaft) from the skin to the anterior wall of the axillary artery was 4.24 +/- 1.49cm (2.25-7.75 cm) in men and 4.01 +/- 1.29 cm (2.25-6.5 cm) in women. Hopefully, thisstudy will facilitate the use of this block. Implications: We sought a consistent, palpablelandmark for facilitation of the infraclavicular brachial plexus block. We used magneticresonance images of the brachial plexus to determine the depth and needle orientation

needed to contact the brachial plexus. Hopefully, this study will facilitate the use of this block.

(Anesth Analg 1998;87:870-3)


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Section Editor: Denise J. Wedel.

The infraclavicular approach to brachial plexus block is an underused but effectivetechnique. Anesthesiologists may opt for more familiar techniques of brachial plexusanesthesia, such as the axillary approach, given the common lack of experience with this

technique and significant variation in infraclavicular anatomy among patients. Nevertheless, advantages of the infraclavicular approach include the ability to performthe block with the patient's arm in any position, avoidance of the neurovascular structuresof the neck, minimization of the risk of pneumothorax, and ease of securing a continuous

brachial plexus catheter to the chest wall at this site [1-4] . Magnetic resonance imaging(MRI) has emerged as the preferred radiological modality for studying the brachial

plexus and the corresponding anatomy [5]. The purpose of this study was to use MRI andcadaver sections to define the anatomic measurements and variation relevant to theinfraclavicular block to establish the orientation and depth of simulated needle placementrequired to reach the brachial plexus by using an infraclavicular/coracoid approach.

MethodsAfter obtaining institutional review board approval, we reviewed the oblique parasagittalT1-weighted magnetic resonance images of the brachial plexus from patients undergoingimaging for other reasons. The oblique parasagittal view is used routinely in ourinstitution to obtain optimal intersection (90[degree sign]) with the brachial plexus.Patients with distorted brachial plexus anatomy from mass effect or postproceduralchanges were not included. Included in the review were 20 male and 20 female patientsimaged in the supine position with the arms adducted, simulating the usual position forinfraclavicular/coracoid block. The mean (range) age of the patients was 53.6 +/- 15.6 yr(26-82 yr). Using scout films, we identified the parasagittal section 2 cm medial to the tip

of the coracoid process. Along this oblique imaging section, we located a pointapproximately 2 cm caudad to the coracoid process on the skin of the anterior chest wall.From this point, we determined the simulated needle direction required to contact theanterior aspect of the axillary artery (neurovascular bundle) and measured the depth foreach subject ( Figure 1 ). A representative image used in the study with a corresponding linedrawing is depicted in Figure 2 . In addition to MRI studies, parasagittal cadaver sectionswere prepared to further identify the anatomy relevant to this infraclavicular/coracoid

block ( Figure 3 ).


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Figure 1. Magnetic resonance imaging measurements for localization of the brachial plexus on oblique parasagittalsections.

Figure 2. Representative magnetic resonance image used for study measurements.


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Figure 3. Sagittal cadaver section through the brachial plexus at the coracoid process level.

Results

At the point 2 cm medial and 2 cm caudad to the tip of the coracoid process, the direct

posterior placement of a needle would contact the cords of the brachial plexus where theysurround the second part of the axillary artery in all images ( Figure 4 ). The distance fromthe skin to the anterior wall of the axillary artery was 4.24 +/- 1.49 cm (2.25-7.75 cm) inmen and 4.01 +/- 1.29 cm (2.25-6.5 cm) in women. ( Table 1 )

Figure 4. Anatomic landmarks for the infraclavicular/coracoid block.


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Table 1. Demographic Data

Discussion

Our description of the coracoid approach to infraclavicular brachial plexus block may provide advantages over existing techniques. Raj et al. [4] described an approach toinfraclavicular block using lateral needle orientation to overcome the risk of

pneumothorax inherent with blocks performed under the clavicle with the needle directedmedially. Other techniques using lateral needle angulation or different landmarks forinfraclavicular blocks have been described. The technique described by Sims [3] has amore medial and cephalad needle entry site with a inferior and lateral needle angulation.Whiffler's technique [6] uses a needle entry site that is most often inferior and medial tothe coracoid process determined by palpation of vascular landmarks with the affected armabducted and the relevant shoulder depressed. The needle direction, such as that wedescribe, is directly posterior. The depth of needle insertion required to reach the brachial

plexus often requires the entire length of the needle (51 mm). The risk of penetrating the


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thoracic cavity, as noted in the preliminary cadaver study, was zero with this method.Kilka et al. [7] studied 175 patients undergoing surgery of the upper limb and anesthetizedthem using an infraclavicular approach based on previous anatomic studies. They dividedthe distance between the fossa jugularis and the ventral process of the acromion intoequal parts and inserted the needle under the clavicle at the midpoint. The needle was

passed directly posterior. A nerve stimulator was used to obtain muscle contractions inthe area to be operated on with a current


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REFERENCES

1. Wedel DJ. Peripheral nerve blocks. In: Wedel DJ, ed. Orthopedic anesthesia. New York, ChurchillLivingstone, 1993:256-71. [Context Link]

2. Brown DL. Brachial plexus anesthesia: an analysis of options. Yale J Biol Med 1993:66:415-31. [Medline Link] [Context Link]

3. Sims JK. A modification of landmarks for infraclavicular approach to brachial plexus block. Anesth Analg1977;56:554-5. [Context Link]

4. Raj PP, Montgomery SJ, Nettles D, Jenkins MT. Infraclavicular brachial plexus block: a new approach.Anesth Analg 1973;52:897-904. [Medline Link] [Context Link]

5. Blair DN, Rapoport S, Sostman HD, Blair OC. Normal brachial plexus: MR imaging. Radiology1987;165:763-7. [Medline Link] [Context Link]

6. Whiffler K. Coracoid block: a safe and easy technique. Br J Anaesth 1981;53:845-8. [Medline Link] [Context Link]

7. Kilka HG, Geiger P, Mehrkens HH. Infraclavicular vertical brachial plexus blockade: a new technique ofregional anaesthesia. Anaesthesist 1995;44:339-44. [Medline Link] [Context Link]

Accession Number: 00000539-199810000-00023

Copyright (c) 2000-2001 Ovid Technologies, Inc. Version: rel4.3.0, SourceID: 1.5031.1.149


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Fig 1. The posterior wall of the interscalene space is pro-vided by the middle scalene muscle.

7iichniquc

The patient is placed in the dorsal recumbent position with thehead turned somewhat to the opposite side. The rotationshould not be so great that it stretches the II~L~SC~CS of the neck

because this makes palpation difficult, The ipsilateral shoulder is lowered by asking the patient to reach for his knee. Thismaneuver, by lowering the clavicle, improves the access to the

Fig 3. The prevertebral fascia, as it extends laterally, splits toinvest the scalene muscles.

trunks. After the procedure has been explained to the patient,the lateral border of the clavicular (lateral) head of thesternocleiclomastoid muscle is located by asking the patient tolift his head slightly off the table. The index finger of the

palpating hand is placed behind this muscle at the level of C6(the level of the cricoid cartilage). When the patient replaces

Fig 2. The anterior wallis provided by the ante-rior scalene muscle.The rootsof the plexusleave the cervical trans:verse processes, de-scend within the interscalene space toward thefirst rib, above whichthey combine to formthe three trunks of theplexus.


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Fig 4. Thus,anterior sealrior fasciamuscle formthe plexus.

the posterior fa: ;cia of theene muscle and the anteof the middle scalenea fa scial sheatl n around

his head on the table, the muscle relaxes and the palpatingfinger moves medially behind it, and comes to lie on the bellyof the anterior scalene muscle. The palpating finger is nowrolled laterally across the belly of the anterior scalene muscleuntil it encounters the interscalene groove, the space betweenthe anterior and middle scalene muscles. Once the groove is

identified, the index finger is moved as far down toward theclavicle as possible. In some patients movement of Ihe palpat-ing finger inferiorly is obstructed by the omohyoid muscle thatcrosses the interscalene groove at this level; and if this is thecase, the groove can usually be picked up 1 cm inferiorly. If not,the block is carried out at this level. If the groove can befollowed all the way to the clavicle, the pulsation of the

subclavian artery can usually be felt where it emerges from between the scalenes, although palpation of the artery is notessential. At this point a 22 gauge 1 l/2 inch, short bevel,immobile needle* is inserted just superior to the palpatingfinger; and once it is through the skin, it is advanced directlycaudad deep to the finger. A paresthesia below the shoulder or

an appropriate twitch in response to a nerve stimulator confirms that the needle is properly placed within the subcla-vian perivascular space. As may be seen in Figure 6, the needleis inserted slightly closer to the middle scalene than to theanterior scalene muscle; and as it is advanced, because thethree trunks are stacked vertically one on top of the other, thereare three opportunities for a paresthesia: if the needle does not

Fig 5. Once formed, the three trunksof the plexus cross the first rib in thesubciavian perivascular space, a lat-eral extension of the interscalenespace. Note that the three trunks arestacked on top of one another at thislevel, and they lie closer to the middlethan to the anterior scalene muscle.


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was vertical, ie, perpendicular to the long axis of the body (andto the direction of needle insertion in the subclavian perivalar technique)

Fig 7. The lnterscalene Technique: the needle is inserted intothe interscalene space mostly mesiad, but slightly dorsal andslightly caudad, again, in one of the long axes of the space,and closer to the middle than to the anterior scalene muscle.

considered a complication, but rather an expected sequel of interscalene block.s Nonetheless, even though phrenic block isasymptomatic in healthy patients, all of the supraclavicular techniques should be considered to be contraindicated in

patients with compromised respiratory function, because acuterespiratory failure has been described secondary to diaphrag-matic paralysis in one such patient following an interscalene

block. Furthermore, bilateral interscalene block should bestaggered or avoided altogether, even in healthy patients.Horners syndrome is also very common after an interscalenc

block, but this is more of a side effect than a complication and

usually causes no adverse sequelat. There is one case report of severe bronchospasm, however, following an interscalene block in a severe asthmatic, presumably secondary to the sympa-thetic block. In addition, the interscalene technique carrieswith it the risk of an intravascular injection (into the vertebralartery or veins) as well as epidural and/or intrathecal injection,although all of these complications can be avoided or mini-mized by careful attention to proper needle direction.

These two supraclavicular techniques, the subclavian perivas-cular and interscalenc techniques, together with the axillary

perivascular technique, have allowed the present authors to provide safe and effective anesthesia for surgery anywhere onthe entire upper extremity and shoulder girdle with few, if any,

complications. Nonetheless, new techniques continue to bedescribed, all of which involve penetration of and injectioninto the interscalene space, but from a different direction.Interestingly, each of these techniques was designed to de-crease the incidence of pneutnothorax and not to increasethe incidence of SLICCCSS.

Parascalene Technique of Vongvisesand Panijayanond

In 1979 the first of scvcral parascaltne techniques \vasdescribed by Vongviscs and Panija~anond.12,13 Their injectionsite was almost identical to that used in the subclavian

pcrivascular technique,but

the direction of needle insertion

The patient lies in the dorsal recumbent position with a pillowunder his head and with the head turned to the side oppositethat to be blocked. The patient is asked to raise his head to

bring the stcrnoclcidomastoid muscle into prominence, th

lateral edge of that muscle is marked, and the patient is told torelax. The anesthesiologist now places his index finger immedi-ately lateral to the sternocleidomastoid muscle just above theclavicle. The finger is now on the belly of the anterior scalenemuscle and is rolled laterally into the interscalene groove. AnX is marked at a point immediately lateral to the edge of theanterior scalene muscle 1.5 to 2 cm above the clavicle (Fig 8).A 22 G, 4 cm needle attached to a filled syringe is now insertedvertically in an anteropostcrior direction (perpendicular to thetable) and is advanced until a paresthesia is elicited, at which

point the local anesthetic is injected after careful aspiration. If the plexus is missed by the advancing needle, the authors stathat the first rib will be contacted. If, after several attempts, no

paresthesias have been elicited, the authors simply inject theanesthetic solution along the lateral edge of the [anterior scalene] muscle a few millimeters above the first rib in a fanlmanner.] In their first 100 patients the authors reported an89% SL SS rate after the first injection, but they were able toincrease the success rate to 97% by a second, supplementalinjection. They reported no serious complications. The need tosupplement an incomplete block increases the possibility

producing nerve damage, however, if and when the explorinneedle encounters an unresponsive nerve.

Parascalene Approach of Dalens et alin Children

In 1987 the technique described by Vongvises and Panijayanond was modified for use in children by Dalens et al,15 w

______ ANTERIOR SCALENE M U S

____ ----- MIDDLE SCALENE MUSCLE

BRACHIAL PLEXUS

SUBCLAVlAN ARTERYI

Fig 8. The brachial plexus and scalene muscles and the poi(+) at which the needle is inserted for the parascaler technique of Vongvises. (Reprinted with permission.13


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Regional Anesthesia for Hip Surgery

Learning Objectives:

1. Describe the indications and contraindications for the various regionalanesthesia and analgesia techniques for surgery on the hip

2. Describe the relevant neuroanatomy of the lumbar plexus, lumbosacral plexusand innervation to the hip

3. Describe the techniques, local anesthetics and adjuvants used for performingregional anesthesia and analgesia for surgery on the hip

4. Compare and contrast the benefits of regional anesthesia and analgesia versusgeneral anesthesia for both the intra- and postoperative period.


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2000 American Society of Anesthesiologists, Inc.

Volume 93(1) July 2000 pp 115-121

Lumbar Plexus Block Reduces Pain and Blood Loss Associated with Total Hip Arthroplasty[Clinical Investigations]

Stevens, Robert D. M.D.*; Van Gessel, Elisabeth M.D.; Flory, Nicolas M.D.; Fournier, Roxane M.D.; Gamulin,Zdravko M.D.

*Research Fellow. Staff Anesthesiologist. Chief Resident.Received from the Department of Anesthesiology, Pharmacology and Surgical Intensive Care, Hpitaux Universitairesde Genve, Switzerland.Address reprint requests to Dr. Stevens: Department of Anesthesiology, Pharmacology and Surgical Intensive Care,Hpitaux Universitaires de Genve, 1211 Geneva 14, Switzerland. Address electronic mail to:[email protected]

Background: The usefulness of peripheral nerve blockade in the anesthetic management of hip surgery has not beenclearly established. Because sensory afferents from the hip include several branches of the lumbar plexus, the authorshypothesized that a lumbar plexus block could reduce pain from a major hip procedure.

Methods : In a double-blind prospective trial, 60 patients undergoing total hip arthroplasty were randomized to receivegeneral anesthesia with (plexus group, n = 30) or without (control group, n = 30) a posterior lumbar plexus block. The

block was performed after induction using a nerve stimulator, and 0.4 ml/kg bupivacaine, 0.5%, with epinephrine wasinjected. General anesthesia was standardized, and supplemental fentanyl was administered per hemodynamicguidelines. Postoperative pain and patient-controlled intravenous morphine use were serially assessed for 48 h.

Results : The proportion of patients receiving supplemental fentanyl intraoperatively was more than 3 times greater inthe control group (20 of 30 vs. 6 of 29, P = 0.001). In the postanesthesia care unit, a greater than fourfold reduction in

pain scores was observed in the plexus group (visual analogue scale [VAS] pain score at arrival 1.3 2 vs. 5.6 3, P 3) were administered 10 times less frequently (in 2 of 28vs. in 22 of 29 patients, P < 0.0001). Pain scores and morphine consumption remained significantly lower in the plexusgroup until 6 h after randomization (VAS at 6 h, 1.4 1.3 vs. 2.4 1.4, P = 0.007; cumulative morphine at 6 h, 5.6 4.7vs. 12.6 7.5 mg, P < 0.0001). Operative and postoperative (48 h) blood loss was modestly decreased in the treatedgroup. Epidural-like distribution of anesthesia occurred in 3 of 28 plexus group patients, but no other side-effects werenoted.

Conclusions: Posterior lumbar plexus block provides effective analgesia for total hip arthroplasty, reducing intra- and postoperative opioid requirements. Moreover, blood loss during and after the procedure is diminished. Epiduralanesthetic distribution should be anticipated in a minority of cases.

TOTAL hip arthroplasty, one of the most frequently performed surgical procedures, generates significant postoperative pain that may be treated using regional anesthesia. When compared with other regimens, regional anesthesia providessuperior pain relief and may favorably influence outcomes such as blood loss and thromboembolic events. 1 In the case


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of major knee surgery, recent evidence suggests that early rehabilitation may be improved by use of regional anesthetictechniques. 2,3 Peripheral nerve blocks of the lower extremities, which offer many of the advantages of other types ofregional anesthesia, are also reported to circumvent some of the drawbacks associated with these other types. 24 Regional blocks have thus gained acceptance for perioperative management of procedures on the knee and below, bothas a complement to general anesthesia and as an alternative to centroneuraxial analgesia. For surgery of the hip,however, the role of peripheral nerve blockade needs to be defined.

Sensory innervation of the hip involves branches of the lumbar plexus (LP) and the sacral plexus. 5,6 Local anestheticmay be directed to the LP by an anterior approach called paravascular, or 3-in-1 block, 7 or by a posterior approach, ofwhich several methods have been described. 810 The concept of the 3-in-1 technique as a plexus block is controversial

because it does not consistently produce anesthesia of the obturator or lateral femoral cutaneous nerves. 11,12 Moreover, in a recent study of total hip arthroplasty, the benefit of 3-in-1 block in terms of reduced pain scores or opioidrequirement was not clearly shown. 13

Studies show that posterior LP techniques are reliable in their ability to block major LP branches. 11,14 Based on theobservation that the LP innervates a significant portion of the hip region, we tested the hypothesis that an LP blockwould provide effective analgesia for total hip arthroplasty. Ancillary end points, such as blood loss, block side-effectsand complications, postoperative nausea and vomiting, and patient satisfaction, were also assessed.

Materials and Methods

After obtaining institutional review board approval and written informed patient consent, we conducted a randomized,controlled, double-blind trial of 60 consecutive patients undergoing elective total hip arthroplasty during generalanesthesia. Exclusion criteria were contraindications to regional anesthesia, use of opioids during the preoperative

period, and dementia preventing proper comprehension of the study.

Patients were randomly allocated to receive general anesthesia combined with an LP block (plexus group, n = 30) orgeneral anesthesia alone (control group, n = 30). All patients were scheduled for surgery at 8:00 am. After

premedication with 7.5 mg midazolam orally, general anesthesia was induced with 46 mg/kg sodium thiopental and 2g/kg fentanyl and maintained with 0.31% isoflurane and 6070% nitrous oxide. Tracheal intubation was facilitatedwith use of 0.2 mg/kg mivacurium and lungs were mechanically ventilated (end-tidal carbon dioxide, 3038 mmHg [4

to 5 kPa]). Patients were placed in the lateral decubitus position, operative extremity superior. After recovery from useof mivacurium (as assessed by train-of-four stimulation of the ulnar nerve or by the appearance of respiratory effortsinterfering with mechanical ventilation), patients assigned to the plexus group were administered a single-injection

posterior LP block using the approach described by Winnie et al. 8 The LP was localized by inducing contractions of thequadriceps femoris with use of a nerve stimulator (DualStim; Life-Tech, Houston, TX), delivering 0.20.5 mA impulsesof 50 s at 2 Hz linked to a 23-gauge, 100-mm sterile needle (Pole Needle; Top Corporation, Tokyo, Japan). Afteraspiration to ensure absence of blood or cerebrospinal fluid, 0.4-ml/kg bupivacaine, 0.5%, with epinephrine 1/200,000was injected. In the control group, lumbar skin was perforated with use of a needle, but no placebo was administered. Inconformity with the blinded study design, the anesthesiologist responsible for the patient was temporarily absent duringtreatment allocation, leaving the patient in the care of an attending anesthesiologist. The attending anesthesiologistadministered the block when assigned, then transferred the patient to the initial staff. The surgical procedure wasstandardized and was performed with patients positioned as previously mentioned.

Intraoperatively, increments of vecuronium (1 mg) or mivacurium (2 mg) were administered only if warranted tofacilitate the surgical procedure or mechanical ventilation. Hemodynamic goals were to maintain mean arterial pressure(MAP) and heart rate within 70130% of preinduction or baseline levels. MAP increases to more than 130% of baselinewere treated by raising end-tidal isoflurane to 1 vol% and administering boluses of fentanyl, 1 g/kg. A decrease inMAP to less than 70% of baseline was treated with ephedrine, 10 mg intravenously, followed by reduction of end-tidalisoflurane to 0.3%. In the postanesthesia care unit (PACU), a patient-controlled analgesia device was given to all

patients and set to deliver intravenous morphine in 1-mg boluses, with a lockout at 6 min and a 4-h maximum of 40 mg.Patients in the PACU reporting pain greater than 3 on the VAS (0 = no pain, 10 = most severe pain) despite patient-controlled analgesia were administered boluses of intravenous rescue morphine as needed. In addition, all patients


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received propacetamol, 2 g intravenously every 8 h administered shortly before the end of surgery and continued for 24h, and ibuprofen, 400 mg orally every 8 h started on the morning after surgery.

Before selection for the study, a majority of study participants had been enrolled in an autologous blood transfusion program (plexus group, 24 of 30 patients; control group, 19 of 30 patients, P = 0.25). Each patient predonated 2 to 3units of blood during the weeks preceding surgery. In accordance with common practice at the Hpitaux Universitairesde Genve, indications for perioperative autologous blood transfusions were not subject to specific guidelines.

Pain scores at rest and morphine consumption were assessed every 30 min in the PACU and then 6, 12, 24, and 48 hafter randomization by observers who were blind to treatment allocation. Other recorded variables includedintraoperative MAP, heart rate, and end-tidal isoflurane concentration; intraoperative opioid and muscle relaxant use;loss of blood, intraoperative (volume of blood measured in suction canisters and estimated from operative dressings [40ml blood/dressing]) and postoperative (volume of blood recovered in suction drains before removal at 48 h); bilateraldistribution of anesthesia, suggesting epidural spread (tested in the PACU with use of a cold stimulus applied to lowerthoracic and lumbar dermatomes contralateral to the operated hip); evidence for block-related neurologic damage at 48h; postoperative nausea or vomiting; and patient satisfaction with anesthetic and pain management (rated using VAS, 10= very satisfied, 0 = very unsatisfied). All observations were made by blinded assessors.

Statistical Analysis

Based on previous data, 13,15 it was computed that a sample of 30 patients/group would detect a difference betweengroups in mean morphine consumption of more than 20 mg and a difference in VAS pain scores of more than 1.7 cm,with a power of 90% and a two-tailed significance level of 5% ([beta] = 0.1, [alpha] = 0.05). In an analysis made afterobtaining results and using other data, 16 it was calculated that a sample of this size had 90% power to detect adifference of 130 ml in mean operative blood loss. Where relevant, data are presented as the mean SD. Comparisons

between groups of continuous variables (MAP, end-tidal isoflurane concentration, morphine use, pain scores,satisfaction scores, blood loss) were assessed using the unpaired Student t test, whereas comparisons of discontinuousdata (proportions of patients) were evaluated using the chi-square test. P < 0.05 was considered to be significant. Somedata were analyzed using StatMate and Prism software (GraphPad, San Diego, CA).

Results

Preoperative characteristics were similar in the two groups ( table 1 ). Two patients, one in each group, were excludedfrom analysis of postoperative data because of delirium, impeding accurate evaluation. One patient in the plexus groupreceived a dose of local anesthetic incompatible with the study requirement and was excluded from intra- and

postoperative analysis. Bilateral distribution of anesthesia, suggesting an epidural extension of local anesthetic, occurredin 3 of 28 (10.7%) patients undergoing the block.


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Table 1. Preoperative CharacteristicsValues are SD.ASA = American Society of Anesthesiologists physical status;VAS = visual analogue scale.

Data related to anesthetic and perioperative management are summarized in table 2 and figures 1 and 2 . The number of patients requiring supplemental fentanyl and the mean end-tidal isoflurane concentration were significantly increased inthe control group, whereas intraoperative MAP was lower in the plexus group during most of the procedure. Thesedifferences in MAP remained significant even when patients with epidural-type distribution were excluded fromanalysis ( P < 0.01 for the difference between groups in MAP from the twentieth to the sixtieth min of surgery, and P 160 mmHg, diastolic pressure >95 mmHg, or treatment with a medicationused explicitly to treat the patients blood pressure. 21

Diabetes Mellitus.


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Diabetes mellitus was marked by treatment with insulin or oral hypoglycemic agents or an elevated fasting glucose level onmore than one occasion (plasma >140 mg/dl; whole blood >120 mg/dl).

Exclusion Criteria.

Exclusion criteria consisted of the following.

Contraindications to Epidural Anesthesia.

Contraindications to epidural anesthesia were ankylosing spondylitis, bleeding diathesis, and use of systemic anticoagulants.

Contraindications to Hypotensive Anesthesia.

Hemodynamically significant aortic valve or mitral valve stenosis (documented by Doppler echocardiography or cardiaccatheterization) and severe carotid artery stenosis (>70% occlusion) were contraindications to hypotensive anesthesia.

Conditions Seriously Affecting Cognitive Testing Performance.

Deafness, blindness, severe hand deformity or dysfunction, psychosis, and nonfluency in English were conditions that wouldaffect cognitive testing performance and were therefore included as exclusion criteria.

Allocation of Interventions

A blocked randomization schedule was prepared before the start of the trial and was known only by the study statistician.Opaque allocation assignment envelopes were opened by the treating anesthesiologist in the operating room just beforesurgery.

Preoperative Evaluation

The preoperative evaluation performed 17 days before surgery assessed demographic status, including education andoccupational history; medical, psychiatric, and surgical history, including past perioperative complications; medication useand substance abuse; physical examination; and preoperative laboratory values. The Charlson comorbidity score, a weightedindex accounting for the number and seriousness of comorbid medical conditions, was computed for all patients. 22

Cognitive Assessment

The perioperative cognitive assessment protocol has been described in detail, including the definition of a minimallyimportant clinical difference in score for each test (appendix 1). The battery includes 10 tests: the Boston Naming,Controlled Word Association, Digit Symbol, Trail Making A and B, Digit Span, Benton Visual Retention, Benton VisualRecognition, MattisKovner Verbal Recall, and MattisKovner Verbal Recognition. Neuropsychologic testing was repeated1 week and 4 months after operation. The Ammons Quick Test 23 for verbal IQ was performed before operation.

Anesthesia Protocol

No premedication was given. All patients received oxygen supplementation via nasal cannula. Oxygen saturation wasmonitored using disposable fingertip sensor pulse oximeters. Cardiac rate, rhythm, and waveform were monitoredcontinuously using a displayed anterior chest lead. Continuous arterial systolic, diastolic, and MAPs were monitored viaradial arterial lines. All patients had central venous catheters placed, and central venous pressures were transduced anddisplayed. Patients with a history of congestive heart failure or severe renal insufficiency also had pulmonary artery cathetermonitoring.


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Bupivacaine (2025 ml), 0.75%, was administered viaepidural catheter using standardized techniques. 24,25 Adjunctivemedications for sedation included midazolam, fentanyl, and thiopental sodium. All patients received a low-dose intravenousepinephrine infusion at an infusion range of 15 g/min to maintain circulatory stability, as previously described. 16,17

Mean arterial blood pressure was maintained within the range of 4555 mmHg or 5570 mmHg during the operative procedure. These levels of hypotension resulted from the epidural anesthetic alone in all patients; no additional agents wereused to decrease blood pressure. The MAP was stabilized in the target range by adjusting the epinephrine infusion rate and

by intravenous infusion of Ringers lactate solution to replace lost blood and to maintain a stable central venous pressure,limited to a maximum of approximately 1.5 l crystalloid. If the MAP decreased to less than the target range despite amaximal infusion rate of 5 g/min epinephrine, an infusion of phenylephrine, boluses of intravenous ephedrine, or both wereused to increase the MAP.

At the end of the surgical procedure, the MAP was increased to 7075 mmHg in both groups using intravenous boluses ofephedrine. In the postanesthesia care unit, both groups had MAP maintained at more than 7075 mmHg with fluidreplacement and intravenous boluses of ephedrine.

Intraoperative Assessment and Data Collection

One of the investigators (J.H.) created a customized software data collection system to record and analyze intraoperative

surgical, anesthetic, and hemodynamic THR data for this study. A research assistant in the operating room entered events ona laptop computer using the program and pop-up menus. The events included incision, cementing, relocation, and so forth,and also all medications and fluids administered during the procedure. Simultaneously, the digital form of the physiologicdata collected and analyzed by the anesthesia monitor was downloaded every 20 s from the monitor to the study computervia an RS 232 connection to allow exact temporal correlation of events and hemodynamic parameters. Downloading ofintraoperative hemodynamic data was successful in 233 of 235 patients; in the other two cases, copies of operating roommonitor trends data yielded adequate intraoperative MAP data.

Intraoperative blood loss was measured using a standardized nursing protocol for THR. Blood loss was calculated as the sumof sponges weighed as they were passed off the surgical field plus the difference between irrigation and suction volumes.

Postoperative Surveillance

The standardized surveillance for cognitive and cardiovascular complications included at least once-daily examinations bystudy personnel from the postoperative anesthesia care unit through the seventh postoperative day or discharge. The

postoperative examination focused on cardiopulmonary and neurologic status. Electrocardiograms were performed within 6h after surgery (in the postanesthesia care unit) and on postoperative days 1, 2, and 3. 26 If significant electrocardiographicchanges (as described in Cardiovascular Outcomes) were observed, cardiac isoenzymes were measured.

Definition of OutcomesChange in Cognitive Function.

The primary outcome of change in cognitive function was within-subject change in score for each neuropsychologic test(score at 4 months after surgery minus the score before surgery). The mean within-subject change in the two blood pressuregroups was compared for each test. Change from baseline to 1 week after operation was also assessed to provide a basis forattributing changes observed at 4 months to the acute perioperative period.

Other Outcomes.

Cardiac complications included the perioperative occurrence of definite or probable myocardial infarction, pulmonaryedema, cardiopulmonary arrest, or death. Definite postoperative myocardial infarction required a CK-MB level of > 5% andone of the following significant electrocardiographic changes: (1) new Q waves lasting more than 0.03 s and more than 1mm in depth in more than two leads in the absence of a new conduction abnormality or a marked change in the QRS axis;and (2) T-wave and ST segment changes lasting more than 48 h in more than two leads (in the absence of new electrolyte


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abnormalities or the new use of digitalis): new inversions of previously upright T waves; new ST depression of more than 1mm; an additional 1 mm or more of ST depression if ST depression existed previously; previously depressed ST segmentsthat returned to normal; or unequivocal ST elevation of more than 2 mm (excluding J point elevation). Changes in T wavesfrom biphasic to inverted or vice versa were not counted as significant T-wave changes.

Probable myocardial infarction required a CK-MB level of >3% and one of the significant electrocardiographic changes.Pulmonary edema required a pulmonary capillary wedge pressure >25 cm water or rales heard over two thirds of the lungfields with a typical chest radiograph for pulmonary edema.

Renal dysfunction was defined as an increase in the serum creatinine of >20% that persisted for >48 h beginning in the first 3days after surgery. In a previous study, this change had a true-positive rate of 67% in identifying patients whose decrease in

postoperative creatinine clearance was >50%. 21

The outcome definition of postoperative delirium was based on an algorithm developed and used in two previous studies ofolder adults undergoing elective joint replacement. 18,27 The diagnosis required the presence of cognitive impairment ofacute onset and fluctuating course and evidence of a significantly impaired attention disorder, plus at least two of thefollowing signs: disorientation, disorganized thought, altered level of consciousness, hyperactive or hypoactive psychomotoractivity, perceptual disturbances, or memory impairment.

Blinding

The anesthesiologists, surgeons, and study personnel recording data in the operating room could not be blinded to the type of blood pressure management. Because the purpose of blinding is to prevent bias in the evaluation of outcomes, the physiciansassessing delirium and cardiac and renal outcomes were blinded to the intraoperative blood pressure range.

Statistical Analyses

Comparison between the two blood pressure groups of within-subject change in score on each of the 10 neuropsychologictests was performed using the Student t test for two samples, using PROC TTEST, which is available in the StatisticalAnalysis System (SAS Institute, Cary, NC). The customary alpha level of significance of 0.05 was adjusted for the 10different comparisons to P < 0.005 (using Bonferroni correction for multiple outcomes). All P values were two tailed. The

one-sample paired comparisons t test was used to test for a significant change from before surgery to 1 week and 4 monthsafter surgery. Examination of simultaneous effects of blood pressure level and other covariates thought to be of potentialsignificance was performed with a multiple linear regression model using PROC GLM in SAS. The dependent variable inthis model was the change from baseline to 4 months after operation on the 10 neuropsychologic tests. The Fisher exact testwas used to compare the incidence of cardiovascular and other categorical outcomes.

ResultsSummary of Patient Screening and Enrollment

During the enrollment period, from March 1993 to August 1995, 461 patients were eligible. The most common reasons forineligibility were nonparticipating surgeon, revision procedure, and not meeting entry criteria. In all, 235 patients agreed to

participate. With regard to the effects of the entry criteria (age > 70 yr or age 5069 yr plus hypertension, cardiac disease, ordiabetes), there was no difference between the younger and older groups in the prevalence of cardiac disease (30% and 27%,respectively) or diabetes (10% and 8%), although more of the younger patients were hypertensive (75% vs. 42%; P < 0.001)

Baseline Preoperative Characteristics and Comparability

One hundred seventeen patients were randomized to the 4555 MAP range and 118 patients to the 5570 MAP range. Therewere no statistically significant differences in baseline demographic and medical characteristics between the two groups(table 1 ). The age range of patients was 50 to 88 yr, with a mean of 72 yr; one half were women; one third of patients wereworking, either full or part time; and none of the patients resided in a long-term care institution. Table 2 shows the baseline


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test scores before surgery on the neuropsychology tests. There were no statistically significant differences between the

baseline scores of the two intervention groups on any of the 10 tests.

Table 1. Baseline Preoperative Demographic and Clinical CharacteristicsNo significant differences between groups.MAP =mean arterial pressure.


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Table 2. Neuropsychologic Test Results at Preoperative BaselineValues are given as mean score (SD). No significantdifferences between groups. A higher score signifies better performance on all tests except trail making A and B, in which alonger completion time signifies worse performance.MAP = mean arterial pressure.

Intraoperative Management

All patients received epidural anesthesia except two patients who had inadvertent injections of 0.75% bupivacaine into thesubarachnoid space resulting in a total spinal, which was diagnosed by shallow ventilation and a decrease in oxygensaturation to the low 90s. One patient had tracheal intubation and the other received assisted ventilation for 30 min. Neither

patient was eliminated from the study.

The overall mean intraoperative MAP in the lower MAP range group was 50 3.6 (SD) mmHg, compared with 65 4.8(SD) mmHg in the higher MAP group ( P < 0.0001). Variability around the mean MAP was minimal, with a mean standarddeviation around the mean MAP of 3.2 mmHg in the lower and 4.4 mmHg in the higher MAP group. In the 4555 MAPgroup, less than 14% of all MAP measurements exceeded the upper limit of 55 mmHg. In the 5570 MAP group, only 2.5%of all MAP measurements were less than the lower limit of 55 mmHg. The mean duration of surgery in both groups was 75min.


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As expected, the percentage of patients who receiv

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Regional Anesthesia Syllabus V1.7