Ultrasound imaging techniques for regional blocks in intensivecare patients

Albrecht Wiebalck, MD, PhD; Thomas Grau, MD, PhD

U ltrasound imaging tech-niques are used in anesthesiafor diagnostic procedures, forperipheral blocks, and for

neuroaxial anesthesia. Over the years,there have been several attempts to re-duce failure in regional anesthesia proce-dures by varying the needle trajectoryand evaluating the stimulation tech-niques to optimize the puncture proce-dure.

More recently, several groups have de-veloped techniques and methods for anultrasound-guided demonstration of neu-ral structures to enable ultrasound-guided puncture procedures in regionalanesthesia. Techniques were developed todetect nerve roots and better define thesurrounding tissue (1–3). The on-line ap-plication of catheters and needles for safeplacement of blocks was also demon-strated (4–6). Today, many of these tech-niques are established; needle and cathe-ter manipulations and the placement ofmedication can now be controlled effec-tively (7–11).

New methods involving imaging tech-niques in the puncture procedures usedfor regional anesthesia are closely relatedto the modern possibilities for regionalanesthesia. The high-frequency linearprobes and depiction processing of thenewer generations of ultrasound ma-chines allow detailed definition of ana-tomic structures, especially using the“small-parts” ultrasound technique;these new techniques also allow examina-tion of the nerve roots before performingpuncturing procedures. Success rates ofnearly 100%, with reduced processingtime and delay until complete analgesia,have been demonstrated (12, 13). Thus,ultrasound-guided techniques have re-duced misplacement and failure in clini-cal practice.

The safer and more effective place-ment of the medication allows for reduc-tion of the amount of administered drugsolution, which might be of importancein the critically ill, in children, and inpatients who need more than one block(i.e., nervi femoralis and ischiadicusblock) (14, 15).

Indications of RegionalAnesthesia in Critically IllPatients

Regional anesthesia is indicated formany critically ill patients and a valuableoption for several reasons. The first indi-cation is pain therapy. It is helpful espe-

cially for those who are traumatized orwho have undergone surgery. Regionalanalgesia provides the most effective paintreatment: pain can be avoided with min-imal doses of medication. Hence, side ef-fects of pain therapy are minimized.

Systemic analgesia, in contrast, is ofminor quality because pain reduction isless effective and side effects, like seda-tion, ventilatory depression, or reductionof bowel activity, may slow down the pro-cess of recuperation. Furthermore, re-gional analgesia allows for a better out-come of joint functionality because earlytraining without pain results in bettermobility, shorter hospital stay, and lowercosts (16).

The second indication for regional an-esthesia techniques is sympathicolysis.Many studies show that stress is reduced,especially with neuroaxial techniques.They lower the rate of heart infarctions,shorten postoperative and posttraumaticileus, and together with other means, im-prove the outcome and shorten thelength of intensive care unit stay (17).

The third indication for regional anes-thesia is the prevention of chronic pain.Patients with amputations, thoracoto-mies, and other painful operations or se-vere trauma develop chronic pain in up to70% of cases (18). They represent about15–25% of all chronic pain patients,causing costs of 40 billion euros per yearin Germany. Regional analgesia is the

From the Department of Anesthesiology, IntensiveCare, Palliative, and Pain Medicine, University ClinicsBergmannsheil, Bochum, Germany.

For information regarding this article, E-mail:Albrecht.Wiebalck@ruhr-uni-bochum.de.

Copyright © 2007 by the Society of Critical CareMedicine and Lippincott Williams & Wilkins

DOI: 10.1097/01.CCM.0000260676.90475.00

Ultrasound imaging techniques have gained great popularity inanesthesia during the last decade. They have been shown to allowbetter quality of regional blocks, improving the outcome of pa-tients and reducing the costs at the same time, for two majorreasons. First, ultrasound imaging provides information of theindividual anatomic structure and abnormalities before puncture.Second, the ultrasound-guided puncture is displayed in real time,and this enables the physician to correct the direction of theneedle, both to improve the spread of local anesthetics and toavoid tissue damage. Ultrasound imaging allows control, even in

difficult cases and in situations with variations of normal anatomy.Even positioning dependent variations of nerve roots can be man-aged most effectively. In addition, the time can be reduced consid-erably to perform regional blocks; the onset time is shorter, and thequality of blocks is better. So, ultrasound imaging techniques areroutinely applied in the University Clinics Bergmannsheil, Bochum,Germany. (Crit Care Med 2007; 35[Suppl.]:S268–S274)

KEY WORDS: ultrasound imaging; quality of regional anesthesia;regional block; time savings; cost savings; doughnut sign; fasci-cles; short onset time

S268 Crit Care Med 2007 Vol. 35, No. 5 (Suppl.)

most effective method to reduce the sub-sequent development of chronic pain.

However, contraindications and diffi-culties in placing a regional analgesiacatheter must not be overseen. Infec-tions, bleedings, especially in the epiduralspace, and positioning of the patient dur-ing placement of the catheter require anindividual decision for each patient.Schulz-Stubner et al. provide a goodoverview on these problems (19).

Technique of Ultrasound-GuidedRegional Anesthesia

The mainstay of a successful ultra-sound-guided regional block is the visi-bility and recognition of both the neuraltissue and the needle. On one hand, thephysician has to discern different types oftissues such as connective tissue, ten-dons, and nerves to know where to aim.On the other hand, the physician shouldbe able to follow the tip of the needle. Thefollowing sections describe importantfactors for ultrasound imaging of nervesand needles.

Nerve Imaging with Ultrasound. Nerveimaging with ultrasound is a special sub-ject. Nerve roots are usually composed ofconnective tissue and nerve fibers. The con-nective tissue consists of highly com-pressed collagen fibers with hyperechoicmaterial and is usually connected with ves-sels for nutritional purposes. The nerve fi-bers are highly insolated by Schwann cells.They are densely packed, and together, theyform the nerve.

The neural tissue is, on one hand,highly lipophil and, on the other, hypo-echoic when using ultrasound for imag-ing. Dependent on several factors, thequality of the discrimination between thehypoechoic nerve roots and the hypere-choic fibers is extremely variable. Themost important factors are the angle be-tween the needle and beam, nature ofthe surrounding tissue, distance betweenthe nerve and probe, and frequency of thetransducer.

Principally, nerves can be demon-strated in the short-axis view (transversecross-sectional plane)—they present as around, oval, or triangular shape—or inthe long axis as longitudinal structures.It has not been completely understoodwhy cross-sectional pictures of fascicles(interscalene block) represent hypo-echoic and more peripherally locatednerves impress more by a anisotropichoneycomb structure. Please compareFigures 1–7.

Tendons might resemble peripheralnerves because they have an anisotropicstructure, too. The easiest way to differ-entiate between nerves and tendons is tofollow the questionable structure alongits course. Tendons change their cross-section and end in muscle and bone tis-sue, whereas nerves do not.

Needle Imaging with Ultrasound. Nee-dle selection and guidance have great in-fluence on the performance of a block.Larger-bored needles (e.g., 18 gauge) aremore readily visualized and easier to di-

rect under ultrasound control. They arepreferred for deep blocks (e.g., an infra-clavicular block).

Smaller-bored needles (e.g., 22 or 24gauge) are harder to see but adequatelyvisualized during more superficial blocks(e.g., the axillary block). The authors pre-fer small needles, in the conviction thatthey cause less tissue damage.

Visibility depends on more factors, in-cluding frequency of transducer, distancebetween needle and probe, angle betweenneedle and beam, and nature of sur-

Figure 1. Adult patient, interscalene area. Description of the sonoanatomy with the musculi scalenusanterior and medius and the nerve roots C5–C8. M, musculus; ant, anterior.

Figure 2. Adult patient, interscalene region after administration of local anesthetic solution. Descrip-tion of sonoanatomy. The picture shows an increased size and echogenicity of the nerve roots and ahomogeneous distribution of the hypoechoic local anesthetic solution. M, musculus; ant, anterior.

Figure 3. Adult patient, infraclavicular area. Description of the sonoanatomy with vena (V) subclavia,arteria (A) subclavia, and the infraclavicular plexus. M, musculus.

S269Crit Care Med 2007 Vol. 35, No. 5 (Suppl.)

rounding tissue. Note that the needle isbetter seen when the bevel faces theprobe. Avoid air bubbles in syringes tomaintain optimal visibility. Principally,needles can be demonstrated in theshort-axis view (transverse cross-sec-tional plane), in which they present asround or oval shapes, or in the long axis,in which they present as straight lines.

General Remarks on Ultrasound-Guided Needle Advancements. Choose anoptimal point of insertion. It should allowfor reaching all necessary points by oneinjection (try for axillary block as well),without several perforations of the skin,and is best with only one perforation. Donot perforate superficial vessels, and donot insert the needle in lines or wrinkles

to avoid the higher degree of moisture,which favors infections of the insertionpoint around catheters. This is crucial inintensive care patients.

Needle control is extremely important.There should be no advancement of theneedle without identification and local-ization of the tip. Possible means are di-rect visualization, shadow of the needle,movements, tissue displacement, and lastbut not least, injection of a small volume.The authors use much smaller volumesthan recommended by Gray (20) (i.e.,0.1–0.5 mL of solution). More solution isnot necessary to identify the position ofthe needle tip if it is close to or in theplane of ultrasound. Recognize vitalstructures (e.g., vessels and pleura) adja-cent to the target nerves and avoid unin-tentional puncture.

Theoretically, the nerve and needlemay be visualized in four different posi-tions (20). Both structures are seen in theshort-axis and the long-axis view, respec-tively, or both structures are seen in dif-ferent axis views: the nerve in the long-axis and the needle in the short-axis viewor vice versa.

The authors prefer the short-axis viewfor both the nerve and the needle becausethe identification of nerves is easy due tothe patchy pattern, nerve images are sta-ble during probe manipulations, circum-ferential spread of local anesthetics ismore easily assessed, and the needle tra-jectory is shorter.

This proceeding offers the greatestsafety and ease of performance. In criticalmoments, small manipulations with theprobe allow for combining the short-axisview with oblique planes, resulting in amore three-dimensional imaging of thesurrounding structures.

When all of these points are taken intoaccount, the advancement of the needleto the nerves is less limited in compari-son with the traditional landmark tech-niques. Physicians may deviate from thelandmark rules to optimize the trajectoryin accordance to the individual conditionsof the present patient. They may choosewhere to insert the needle into the skin, inwhich direction to forward the needle, andhow much local anesthetic solution is re-quired until the neural structure is com-pletely surrounded by the injected fluid.

Furthermore, needle control by ultra-sound imaging techniques allows a moreeffective needle approach to the nerves,the so-called V technique. The V de-scribes the movements of the needle: theadvancement of the needle to one side of

Figure 4. Adult patient, infraclavicular region after administration of anesthetic solution. Descriptionof sonoanatomy and of the distribution of the medication and demonstration of the three majorfascicles. M, musculus; V, vena; A, arteria.

Figure 5. Adult patient, axillary region before administration of anesthetic solution. Description ofsonoanatomy and of the localization of the peripheral nerves. M, musculus; N, nervus; A, arteria; Ncutaneus antebrach med, nervus cutaneus antebrachii medialis.

Figure 6. Adult patient, axillary region after administration of local anesthetic solution. Description ofsonoanatomy and of the localization of the peripheral nerves. Note the increased diameters of thenerves in comparison with Figure 5. N cutaneus antebrach med, nervus cutaneus antebrachiimedialis; M, musculus; A, arteria.

S270 Crit Care Med 2007 Vol. 35, No. 5 (Suppl.)

the nerve and injection of local anestheticsolution until that side of the nerveshows a sufficient fluid layer. Then, theneedle is partially pulled back and redi-rected to the other side of the nerve.Again, the required amount of fluid isadministered until sufficient fluid sur-rounds the total circumference of thenerve. By this technique, the doughnutsign is achieved more effectively, withless local anesthetic solution than with asingle deposit.

Ultrasound-Guided Blocks ofUpper Limb

Interscalene Block. This block is usu-ally performed with an axial/transversalscan at the level of the cricoid. The mostimportant structures can be identified eas-ily: the carotid artery, the jugular vein, thelateral end of the musculus sternocleido-mastoideus, and the musculi scalenus an-terior and scalenus medius (Fig. 1).

With short-axis scanning and understerile conditions, the nerves can be iden-tified in most patients as the roots ofC5–C8, with C5 located closer to the sur-face and the other in a row, closer to thevertebral column.

First, a small needle (24 gauge) is usedfor the initial injection. Local anestheticsolution, 1 mL, is administered for skininfiltration, 9 mL for direct blocking ofthe nerve roots C5–C8. Slow advance ofthe needle with contemporary injectionof small amounts of local anesthetic so-lution allows for a painless proceedingand a good localization of the needle tipat the same time. When the needle tip isclose to the nerve roots, the remaininglocal anesthetic solution is injected.

Usually, homogeneous distribution oflocal anesthesia medication can be de-tected as a hypoechoic halo around thenerve roots. Within a short time, there is

an enhancement effect due to the in-creased volume of the nerve roots C5–C8(Fig. 2). Second, the 18-gauge Contiplexneedle (B. Braun, Bethlehem, PA) is in-serted into the anesthetized skin and ad-vanced to the nerve roots. Depending onthe innervation of the surgical field, theneedle is directed more deeply to the seg-ments C7/C8 or more to the upper seg-ments C4/C5. Then, again 10 mL of localanesthetic solution is administered, themandarin is removed and the catheterpassed through the mandarin-free Conti-plex needle. For the ease and speed of thewhole procedure, the catheter should beadvanced �10 cm. After removal of theintroducer, the catheter should be pulledback into the optimal position. The opti-mal length of the insertion of the cathe-ter is calculated as the depth of needleinsertion plus 3–5 cm, usually 6–8 cm.Then, the catheter is fixed to the skin bya suture. For better fixation, a small pieceof tape is wrapped around the catheterclose to the skin, preventing the threadfrom gliding along the catheter.

Finally, the correct position of thecatheter is verified. The last 20 mL oflocal anesthetic solution for a sufficientblock is given through the catheter. Ul-trasound imaging must reveal an in-crease of the hypoechoic halo around thenerve routes. Otherwise, the tip of thecatheter might be outside the effectivearea, requiring a new catheter placement.

Infraclavicular Block. For blockingthe plexus brachialis in the infraclavic-ular region, a linear scanning plane ischosen directly below the clavicle. Thecharacterizing structures—axillary ar-tery, subclavian vein, and musculuspectoralis—are easily identified. Atdepth, usually the first rib, the pleuraand the surface of the lung can be rec-ognized. Lateral to the artery, the

plexus can be seen as a crescent ortriangular shape (Fig. 3).

The point of needle insertion— de-fined by optimal visualization of the es-sential structures—is different from thatof the traditional vertical infraclavicularpuncture technique. It is located 1–3 cmmore lateral.

The puncture is performed under ster-ile conditions. First, with a small needle(24 gauge), 10 mL of anesthetic solutionis used: 1 mL for skin anesthesia and 9mL in the area around the triangularshape. The enhancement effect is easilyvisible within 30 secs (Fig. 4). Then, thethicker 18-gauge Contiplex needle is usedto administer another 10 mL of medica-tion for easier insertion of the catheter incase a continuous block is needed. Thetechnique of inserting the catheter, de-termining the optimal length, fixation,and evaluation of the function are de-scribed in detail in the previous section.

Axillary Block. Use an axial scan tovisualize the humerus, the axillary artery,the nerve roots surrounding the artery,and the musculus coracobrachialis,which is located lateral to the artery (Fig.5). Veins in the axillary region are easilycompressed by a light pressure whenguiding the probe in the axilla.

The nervus musculocutaneus can eas-ily be identified within the musculus cor-acobrachialis. The nerve emerges the lat-eral fascicle close to the median nerve.Usually, it is nicely visible more anteriorand a little lateral of the artery. It ishelpful to know that the nervus muscu-locutaneus moves away from the arterythe more distal the probe is held and viceversa; the nerve is located closer to theartery the more cranial the probe is glid-ing, almost like a silverfish swimmingback and forth to the artery when theprobe is gliding up and down the axilla.

The other three nerves are locatedclose around the artery, with the nervusradialis being the deepest behind the ar-tery, the nervus medianus more anteriorand lateral, and the nervus ulnaris moreanterior and medial of the artery.

After identification, each nerve can beblocked with 5–10 mL of local anestheticsolution. Start the axillary block with thenervus musculocutaneus. With a shortneedle, the injection point is about 1–2cm anterolateral to the injection point forthe other three nerves.

Then, advance the needle to the radialnerve first because depositing the localanesthetic solution behind the artery willpush it to the surface and, starting with

Figure 7. Adult patient, distal sciatic region after administration of anesthetic solution. Axial scan.Description of the doughnut phenomenon: the nerves are completely surrounded by fluid. N, nervus.

S271Crit Care Med 2007 Vol. 35, No. 5 (Suppl.)

the other two nerves, would extend thetrajectory to the radial nerve. Further-more, placement of the catheter behindthe artery is more successful than place-ment elsewhere.

The enhancement effect can be dem-onstrated with a more hyperechoic signaland a 2- to 3-fold increase in the volumeof the nerves (Fig. 6). The technique ofinserting the catheter, determining theoptimal length, fixation, and evaluationof the function are described in detail inthe discussion of the interscalenus block.

Ultrasound-Guided Blocks ofLower Limb

Block of Distal Nervus Ischiadicus.The best posture of the patient is supine,with the leg slightly elevated (i.e., sup-ported by a pillow or a box), providingfree access for the probe from below.Demonstrate the artery, the peroneus,and the tibial nerve. Advance the probein a more proximal direction whereboth nerves emerge the sciatic nerve.Apply a needle (18-gauge Contiplex) inline. Apply medication around thenerve. Hypoechoic signal and even hy-perechoic depiction can be seen. Often,the doughnut sign can be demon-

strated. For this block, it is essential tohave the doughnut sign around thewhole nerve (Figs. 7 and 8). The tech-nique of inserting the catheter, deter-mining the optimal length, fixation,and evaluation of the function are de-scribed in detail in the discussion of theinterscalenus block.

Block of Nervus Femoralis. The bestposture of the patient is supine. Demon-strate the femoral nerve, artery, and veinin the groin, slightly below the ligamen-tum inguinale. The femoral nerve pre-sents often as triangular, most often lat-eral to the artery. Sometimes, it isdifficult to identify it before injection oflocal anesthetic solution. After injection,it appears brighter and is more easilyseen (Fig. 8).

Choose a 24-gauge needle, infiltrate theskin and the underlying tissue with 1–2mL, advance the needle tip to the spacebetween the femoral artery and nerve, andinject the remaining volume of local anes-thetic solution. Take an 18-gauge Contiplexor an appropriate needle and inject another10 mL in the space between the artery andnerve before insertion of the catheter. Forfurther details, see the discussion of theinterscalenus block.

Ultrasound and EpiduralAnesthesia

The loss-of-resistance technique is thestandard approach to identify the epi-dural space. Although this technique hasbeen used for a long time, only about60% of punctures are successful at firstattempt (21). Apart from the degree ofpersonal experience, this high failure ratehas been attributed to the quality of an-atomic landmarks and of patient posi-tioning. It may therefore be easier toidentify the epidural space by ultrasonog-raphy whenever difficulties arise in con-nection with these variables.

Ultrasound imaging techniques allowthe demonstration of the lumbar epiduralspace. This might be of greater impor-tance in special groups of patients like:

Children, because the distance betweenskin and epidural space is unknown andmuch shorter (14, 22).

Parturients, because puncture is compli-cated in this group by weight gain, edema,and less elastic collagen fibers (21).

Patients with anatomic abnormalities (3).

Patients with limited optimization ofpositioning, like those in the intensivecare unit.

Best used are a 5-MHz curved-array ora 7.5-MHz linear probe and a combina-tion of transverse and longitudinal scans(Figs. 9 and 10). It is possible to identifyall relevant landmarks in the thoracic epi-dural space by ultrasound. However, thepotential of ultrasound-guided epiduralpuncture might seem somewhat limited bythe interfering bone structure and the rel-atively deep position of the epidural space,which detracts from the quality of the im-ages obtained. Despite the limited quality ofthe images, the results of these preliminarystudies are encouraging (23–25).

Off-line Technique. With the off-linetechnique, an ultrasound scan is per-formed in the transversal and the longi-tudinal planes. The examination is per-formed directly before the puncture.With these scans, the physician is pro-vided with information about the config-uration of the spine, such as kyphosis,lordosis, or scoliosis. Usually, lateral de-viations of the processus spinosus and theprocessus articulares in relation to thecorpus vertebrae can be seen very effec-tively (Fig. 10).

Figure 8. Adult patient, distal sciatic region after administration of local anesthetic solution. Longi-tudinal scan. N, nervus.

Figure 9. Adult patient, transversal scan in the lumbar area. Demonstration of the processus spinosi,processus (Proc) articulares, and processus tranversi and depiction of the corpus vertebrae.

S272 Crit Care Med 2007 Vol. 35, No. 5 (Suppl.)

In the longitudinal median scan, thereis also a chance to measure the needletrajectory. The effective needle trajectoryis defined by the cranial and caudal bor-ders of the processus spinosus. The bestpoint for needle insertion is where allstructures can be identified: the skin, theintervertebral ligaments, the muscles,the ligamentum flavum, and the moredeeply located dura mater.

The distance between skin and epi-dural space can be measured for differentapproaches with the distance-measure-ment software of the ultrasound system.The ideal starting point of the punctureand the ideal puncture angle can be mea-sured. With this concept and with theadditional information of the measureddepth of the epidural space, the off-linepuncture with the loss-of-resistance tech-nique is safe, effective, and easy.

On-line Technique. With this tech-nique, usually a paramedian ultrasoundscan is used to visualize intraspinal struc-tures. The puncture itself is performed inthe median plane, and the monitoring ofthe needle processing is performed via theparamedian scan. Nearly all procedures ofpuncture processing can be performed un-der direct control. This concept eases theapplication of epidural and intraspinal pro-cedures. A problem might be that a thirdhand is necessary for holding the probe andproducing effective pictures while usingboth hands for needle guidance or catheterplacement. In addition, all on-line applica-tions have to be performed with sterilesleeves on the ultrasound probe to avoidany contamination.

Usually, these proceedings are ade-quate for epidural punctures in childrenwhen neuroaxial blocks must be per-formed under general anesthesia. Thisconcept can also be used for anesthetizedpatients in the intensive care unit. With

the knowledge of the needle trajectoryand the application of the puncture nee-dles under epidural anesthesia, the punc-ture process is safe and perfect for uncon-scious patients.

Conclusion

Direct ultrasonographic visualizationsignificantly improves the outcome of mosttechniques in peripheral regional anesthe-sia. With the help of high-resolution ultra-sonography, the physician can directly vi-sualize relevant nerve structures for upperand lower limb nerve blocks at all levels.Such direct visualization improves thequality of nerve blocks and avoids compli-cations.

The use of ultrasound seems to en-hance not only the traditional brachialand lumbosacral plexus blocks, but alsoneuraxial techniques. Promising resultshave been obtained in different groups ofpatients: intensive care patients, parturi-ents, and children, in whom most types ofblocks are performed under sedation orgeneral anesthesia.

The benefits of directly visualizing tar-geted nerve structures and monitoringthe distribution of local anesthetic aresignificant. In addition, ultrasound mon-itoring allows the physician to correct theneedle position in the event of maldistri-bution. It is therefore justified to expectphysicians to acquire the skills to useultrasound guidance in clinical practice.The technique can be established in acost-efficient way, as portable ultrasoundsystems with high-frequency probes arenow available. It is hoped that these sys-tems will promote the routine use of ul-trasound guidance in regional anesthesiaand in other fields.

REFERENCES

1. Chan VW, Nova H, Abbas S, et al: Ultrasoundexamination and localization of the sciaticnerve: A volunteer study. Anesthesiology2006; 104:309–314

2. Perlas A, Chan VW, Simons M: Brachialplexus examination and localization usingultrasound and electrical stimulation. Anes-thesiology 2003; 99:429–435

3. Retzl G, Kapral S, Greher M, et al: Ultrasono-graphic findings of the axillary part of the bra-chial plexus. Anesth Analg 2001; 92:1271–1275

4. Chan VW, Perlas A, Rawson RN, et al: Ultra-sound-guided supraclavicular brachial plexusblock. Anesth Analg 2003; 97:1514–1517

5. Sinha A, Chan VW: Ultrasound imaging forpopliteal sciatic nerve block. Reg AnesthPain Med 2004; 29:130–134

6. Sandhu NS, Capan LM: Ultrasound-guidedinfraclavicular brachial plexus block. Br JAnaesth 2002; 89:254–259

7. Grossi P, Allegri M: Continuous peripheralnerve blocks: State of the art. Curr OpinAnaesthesiol 2005; 18:522–526

8. Marhofer P, Greher M, Kapral S: Ultrasoundguidance in regional anaesthesia. Br J An-aesth 2005; 94:7–17

9. Grau T: Ultrasonography in the current prac-tice of regional anaesthesia. Best Pract ResClin Anaesthesiol 2005; 19:175–200

10. Greher M, Retzl G, Niel P, et al: Ultrasono-graphic assessment of topographic anatomyin volunteers suggests a modification of theinfraclavicular vertical plexus. Br J Anaesth2002; 88:632–636

11. Spence BC, Sites BD, Beach ML: Ultrasound-guided musculocutaneous nerve block: A de-scription of a novel technique. Reg AnesthPain Med 2005; 30:198–201

12. Gray AT, Schafhalter-Zoppoth I: Ultrasoundguidance for ulnar nerve block in the fore-arm. Reg Anesth Pain Med 2003; 28:335–339

13. Williams SR, Chouinard P, Arcand G, et al:Ultrasound guidance speeds execution andimproves the quality of supraclavicularblock. Anesth Analg 2003; 97:1518–1523

14. Rapp HJ, Grau T: Ultrasound imaging in pe-diatric regional anesthesia. Can J Anaesth2004; 51:277–278

15. Marhofer P, Schrogendorfer K, Wallner T, etal: Ultrasonographic guidance reduces theamount of local anesthetic for 3-in-1 block.Reg Anesth Pain Med 1998; 23:584–588

16. Capdevila X, Barthelet Y, Biboulet P, et al:Effects of perioperative analgesic techniqueon the surgical outcome and duration of re-habilitation after major knee surgery. Anes-thesiology 1999; 91:8–15

17. Rodgers A, Walker N, Schug S, et al: Reduc-tion of postoperative mortality and morbiditywith epidural or spinal anaesthesia: Resultsfrom overview of randomised trials. BMJ2000; 321:1493

18. Dajczman E, Gordon A, Kreisman H, et al:Long-term postthoracotomy pain. Chest1991; 99:270–274

19. Schulz-Stubner S, Boezaart A, Hata JS: Re-

Figure 10. Adult patient, longitudinal median scan in the lumbar area. Demonstration of the processusspinosus, ligamentum flavum, dura mater, and intrathecal space. Shortest possible (large dotted line)and expected needle trajectory (dashed line) to the epidural space are indicated.

S273Crit Care Med 2007 Vol. 35, No. 5 (Suppl.)

gional analgesia in the critically ill. Crit CareMed 2005; 33:1400–1407

20. Gray AT: Ultrasound-guided regional anes-thesia: Current state of the art. Anesthesiol-ogy 2006; 104:368–373

21. Grau T, Leipold RW, Horter J, et al: The lumbarepidural space in pregnancy: Visualization by ul-trasonography. Br J Anaesth 2001; 86:798–804

22. Kirchmair L, Enna B, Mitterschiffthaler G, etal: Lumbar plexus in children: A sonographicstudy and its relevance to pediatric regionalanesthesia. Anesthesiology 2004; 101:445–450

23. Watson MJ, Evans S, Thorp JM: Could ultra-sonography be used by an anaesthetist to iden-tify a specified lumbar interface before spinalanaesthesia? Br J Anaesth 2001; 90:509–511

24. Grau T, Motsch J, Conradi R, et al: Ultras-chall und Regionalanaesthesie: III. Ultras-chall und neuroaxiale Regionalanaesthesie.Anaesthesist 2003; 52:68–73

25. De Filho GR, Gomes HP, da Fonseca MH, etal: Predictors of successful neuraxial block: Aprospective study. Eur J Anaesthesiol 2002;19:447–451

S274 Crit Care Med 2007 Vol. 35, No. 5 (Suppl.)