Unformatted text preview: Ultrasound Guided Ultrasound Guided Nerve Blocks:
Raymond Graber, MD
University Hospitals Case Medical Center
Case Western Reserve University School of Medicine Goals:
Goals: Discuss rationale for US guidance.
Learn proper techniques of US guidance.
Discuss interesting findings seen with US.
Discuss specific nerve blocks. Landmark Technique For
Landmark Technique For Nerve Blocks: Traditional nerve block techniques are based on the ability to palpate muscles, bones, and pulses. A normal consistent anatomic relationship between nerves and these other structures is assumed. Problems with Landmark Techniques:
Problems with Landmark Techniques:
Anatomic Variations There are normal variations in anatomy.
Some patients have landmarks that are difficult to palpate. History of US Guidance
History of US Guidance 1989: Ting et al used US to examine spread of local anesthetic after axillary blocks.
1994: Reed & Leighton used doppler to identify the axillary artery in an obese patient, and marked the skin prior to axillary block.
1994 (Kapral et al): supraclavicular blocks.
1998 ( Marhoffer): femoral blocks. Benefits of US Guidance
Benefits of US Guidance Ability to see nearby vascular structures
Ability to see nerves (sometimes!)
Ability to visualize the needle approaching the nerve.
Ability to see local anesthetic spread.
Possibility of reducing complications. Can do postop without nerve stim.
Less painful to use US instead of nerve stim when patient has a fracture.
Can perform rescue blocks without nerve stim. Spread of Local:
Spread of Local:
US guidance has demonstrated one possible cause of patchy blocks – incomplete surrounding of the nerve with local anesthetic. If after half the volume of local is injected, inadequate spread is seen, the needle can be repositioned. How Accurate is Nerve Stimulation?
How Accurate is Nerve Stimulation? We used to assume a linear relationship between the threshold stimulating current (the lowest current you can still achieve a twitch at) and the distance from the needle tip to the nerve.
Many authors recommend a current of 0.20.5 ma as a goal. Higher threshold currents would lead to more searching with the needle. Lower currents would mean increased risk of intraneural injection.
The 2 following studies called this dogma into question. In this study, interscalene blocks were done with paresthesia technique. Paresthesia is assumed to indicate contact with the nerve. When a paresthesia was obtained, the nerve stimulator was turned on.
Results: All patients had easily elicited paresthesias… Only 30% of patients exhibited any motor response to electrical stimulation up to 1.0 mA… Conclusion: Elicitation of paresthesia does not translate to an ability to elicit a motor response to a peripheral nerve stimulator in the majority of patients. In this study, needles were placed into pig nerves, then nerve stim turned on to see at what current motor response occurred. Thus, intraneural placement occurred despite presumed “safe” nerve stim currents in 66% of the nerves. Demonstration of Intraneural Demonstration of Intraneural Injection with US: Does US Improve Success Rate?
Does US Improve Success Rate?
RAPM MayJune 2008: US guidance improves success rate of interscalene brachial plexus blockade (99% vs 91%). (Kapral et al)
US guidance improves the success of sciatic nerve block at the popliteal fossa (89.2% vs 60.6%). (Perlas et al)
Both these studies allowed the US group to reposition to needle to ensure good spread of local anesthetic, whereas the nerve stim groups were singe injection. US Guided Nerve Blocks: US Guided Nerve Blocks: Equipment, Terminology & Technical Aspects
The equipment is evolving. High resolution imaging is now available in laptop size equipment. The better the resolution, the easier it is to image nerves. Some equipment examples follow, but more systems are coming on the market. Sonosite 180+
C11 Probe 11mm broadband curved array transducer.
Imaging modes: 2D, Mmode, color power Doppler, directional color power Doppler Physical characteristics: •
• Maximum Depth: 10 cm • • Frequency: broadband 74 MHz Maximum Field of View: 90º Our original device – images hard to interpret. Good for IJ placements. Sonosite C11
HFL38 Probe 38 mm broadband flat array transducer.
Imaging modes: 2D, Mmode, color power Doppler, directional color power Doppler Physical characteristics:
• Frequency: broadband 10
5MHz • Maximum Depth: 6 cm GE 12LRS
US Probe 42 x 7 mm broadband flat array transducer.
Imaging modes: 2D, Mmode, color Doppler, harmonic and compound imaging. Physical characteristics: •
• Maximum Depth: 68 cm • • Frequency: 513 MHz Maximum width of View: 39 mm. Most of the images in this talk are from this device. Equipment & Supplies
Equipment & Supplies Block kit.
Needles – block, skin wheal
Sterile sheath kit (contains gel, sleeve, rubber bands.)
US machine SAX Imaging
SAX Imaging Most commonly used. LAX Imaging
LAX Imaging Rarely used. SAX Out of Plane (OOP) Approach:
SAX Out of Plane (OOP) Approach: Needle is at best seen only in cross section. More commonly, tissue movement is seen as the needle approaches the target. SAX In Plane (IP) Approach SAX In Plane (IP) Approach With this approach, one can see the needle approach the target. However, be aware that it is easy to be a little oblique, and to not actually see the needle tip. Needle Type:
Needle Type: Typical 22 g insulated block needles can be used. Alternatively, 18 g Touhy needles sometimes are used, because are easier visualized, or for catheter placement. OOP approach: Needle diameter would not matter, since the needle is not visualized with this technique. IP approach: A larger diameter needle can be helpful, especially if the nerve is relatively deeper, and a longer needle is required. Technique (1)
Technique (1) IP approach: line up needle in middle of US plane. Penetrate skin and enter under probe. If needle not seen, move probe slightly and slowly to find needle. Technique (2) Move needle to desired location.
Inject 1 ml to verify needle location.
Reposition needle if needed. Technique (3)
Technique (3) Local Anesthetic Spread Examine spread of local. Reposition to next location if desired. With US guidance, is With US guidance, is nerve stimulation still required?
As you get better with US, you rely less and less on nerve stim.
However, may be advantageous to leave nerve stim on at low current for extra feedback on needle tip location. Femoral Nerve Block
Femoral Nerve Block Femoral Nerve Femoral Nerve Origin: The femoral nerve is the largest branch of the lumbar plexus, and is formed from L2,3,4. Femoral N. Anatomy
Femoral N. Anatomy Femoral N. Anatomy Key Points:
Femoral N. Anatomy Key Points: VAN – vein, artery, nerve (from medial to lateral).
Nerve lies on top of iliopsoas muscles.
Nerve to sartorius m. exits and lies superficial and medial to main body of femoral n. Fascia
Lata Note fascias lata and iliaca. Fascia iliaca lies between the artery and the nerve – thus they lie in different compartments. Femoral Nerve Cutaneous Distribution The femoral nerve supplies the anterior thigh and part of the medial thigh, then as the saphenous nerve supplies the medial aspect of the lower leg and ankle. Knee & Hip Bone Innervation
Knee & Hip Bone Innervation
Anterior Posterior Standard Femoral Standard Femoral Block Technique Palpate femoral artery at inguinal crease. Mark a spot 1 cm lateral to pulse.
Advance needle till quadriceps twitch obtained. Issues With Standard Technique:
Issues With Standard Technique:
Body Size Issues With Standard Technique:
Sartorious Twitch Injection should not be done when a sartorius twitch is present, because the nerve may have already exited the sheath.
Sartorius m. Issues With Standard Technique:
Injection Outside Sheath:
Injection Outside Sheath: Femoral N. Ultrasound Imaging (1):
Femoral N. Ultrasound Imaging (1):
Positioning: Patient flat, stomach retracted with wide tape if needed.
Stand on side of block, machine on opposite side.
Try to line up needle, transducer, and US monitor – makes it easier to image your needle. Femoral N. Ultrasound Imaging (2):
Femoral N. Ultrasound Imaging (2):
Holding the Probe: Notice the hand is holding the probe in a way that the side facing us is easily visualized – making it easier to get the needle lined up with the middle of the probe.
Notice that the hand is resting on the patient’s skin. This helps keep the probe from sliding around on the gel. SAX approach. Imaging:
Imaging: Start below crease.
Perpendicular to leg, not parallel to crease.
Look for femoral artery, white triangle.
No! Yes! The white triangle: The white triangle: anatomic correlations Example Images:
Example Images: Lateral Medial Lateral Medial Try to identify the fascial planes and the nerve. Lateral Medial Lateral Medial Lateral Medial Fine Tuning Imaging: Slight rotational and angle adjustments of probe, to get best cross section.
Move probe cephalad to find best compromise between femoral nerve image and depth. (As you move cephalad, the nerve becomes a more distinct bundle. However, it can be harder to image as it gets deeper.) Medial Lateral Medial Lateral Another example. Try to identify the fascial planes and the nerve. Medial Lateral Medial Lateral Medial Lateral Note second artery below femoral artery – the profunda femoris branch. At this location, femoral nerve is also branching out, and harder to image, so best to move more cephalad. The probe is being moved cephalad. Approaches: With Stimulation
Approaches: With Stimulation
IP OOP OOP IP Approaches: No Stimulation
Approaches: No Stimulation Here, an 18 g Touhy needle is being used – easier to see with US, and easier to feel the 2 pops through fascias lata and iliaca. OOP IP Don’t aim for nerve. Aim to pierce fascia iliaca lateral to nerve.
Feel fascial pop, then give 1 ml test dose to confirm location. OOP Geometry
OOP Geometry A good goal for the OOP approach would be that your needle tip approaches the nerve at the point that the ultrasound beam intersects with the nerve. That way, you will be sure to see your test injection. You can measure depth to nerve with US, then use that information as shown. Example of In Plane Approach:
Example of In Plane Approach: Example of Out of Plane Approach
Example of Out of Plane Approach Note that the needle isn’t seen here, but tissue movement shows general track of the needle. Injection:
Injection: More Injection:
More Injection: In Plane – Outside Sheath
In Plane – Outside Sheath An example of a test injection above the fascia iliaca, and probably also above the fascia lata. Out of Plane – Outside Sheath
Out of Plane – Outside Sheath An example of a test injection above the fascia iliaca. One more nice example: a 16 y/o female for an ACL repair. Post injection. Even though nerve is not completely surrounded with local, the block is still usually good. Scenario:
Total Knee Replacement Preop meds: celexecob, gabapentin
Femoral single shot block vs catheter
Pre or postop.
Local by surgeon (helps with sciatic mediated pain). Supraclavicular Supraclavicular and Interscalene Blocks Interscalene Anatomy
Interscalene Anatomy SCM Middle Scalene
Omohyoid Brachial Brachial Plexus Sheath A sheath surrounds the brachial plexus, from the transverse processes all the way down into the axilla. Relations
Relations Brachial plexus is contained within a fascial sheath.
Subclavian artery lies medial to plexus as they cross the 1st rib together.
Note location of phrenic nerve and vertebral artery. Note that either lung or rib may be visualized with US under the plexus. Typical Areas of Block
Typical Areas of Block Classic Interscalene Technique (1) Classic Interscalene Technique (1) The needle is placed in the groove perpendicular to all planes, with a slight caudal angulation.
The classic entry point is at the level of C6, identified by the level of the cricoid cartilage, or where the EJ crosses the SCM. Supraclavicular Block:
Standard Technique The goal of this technique is to inject the plexus near the 1st rib, where the roots have formed into trunks.
The classic technique involved walking across the 1st rib to find the plexus. This was associated with a 15% incidence of pneumothorax.
Many authors have reported variations in technique, to try to reduce the pneumothorax risk. Issues With Standard Techniques:
Issues With Standard Techniques: Body Size Issues With Standard Technique:
Phrenic Nerve Phrenic Nerve Stimulation: Phrenic Nerve Anterior Scalene If you get hiccuping, you are in front of the anterior scalene. Move your needle one groove further back. Issues With Standard Technique:
Posterior Muscle Contraction.
Posterior Muscle Contraction. Posterior muscle contraction are from nerve that have exited the sheath, and lie behind The middle scalene. Move your needle one groove forward. Issues With Standard Technique:
Phrenic Nerve Phrenic Nerve Dysfunction This occurs in 100% of successful interscalene blocks, because we have anesthetized the roots that form the phrenic nerve. It’s incidence is lower and variable in supraclavicular blocks – depends on volume of local used. Issues With Standard Technique:
Injection Injection Outside Sheath: It is possible to get a good twitch and be superficial to the sheath. Injection at this location May result in block of the superficial cervical plexus. Supraclavicular Ultrasound Supraclavicular Ultrasound Imaging:
Positioning: Place roll under operative shoulder to allow better access with needle. Keep needle, transducer and monitor lined up. Supraclavicular Imaging:
Supraclavicular Imaging: Start parallel and adjacent to clavicle.
May have to rotate probe slightly to get a good cross section. Lateral Medial Here is a nice example of the brachial plexus to the left of the subclavian artery. Lateral Medial Look for subclavian artery, with plexus sheath on lateral aspect.
Look for subclavian artery, with plexus sheath on lateral aspect. Lateral Medial Interscalene Imaging:
Interscalene Imaging: Scan up from supraclavicular position. Moving the probe cephalad. Posterior Anterior Look for brachial plexus bundle between scalene muscles. Look for brachial plexus bundle between scalene muscles. Posterior Anterior Supraclavicular Approach:
Supraclavicular Approach: Use inplane approach only – so position of needle relative to lung is always known. In Plane Lateral Medial Interscalene Approach:
Either in plane or out of plane approaches can be used. IP OOP Posterior Anterior Another example. Try to identify the anatomy. BP Ant Scalene Middle Scalene The brachial plexus is nicely delineated. Same patient – with inplane approach injection from the left side of the screen. The needle is not visualized, but local anesthetic can be seen entering the sheath. Local
anesthetic Same patient – needle now imaged. Local anesthetic can be seen pooling around the plexus. Scenario:
Shoulder Surgery Interscalene vs supraclavicular blocks
GA by LMA or ETT. Sensory Innervation for Sensory Innervation for Shoulder Surgery Brachial plexus skin innervation. Sensory Innervation for Sensory Innervation for Shoulder Surgery Cervical plexus skin innervation. Sensory Innervation for Sensory Innervation for Shoulder Surgery
T23 skin innervation.
Only occasionally required for shoulder surgery. Pros and Cons
Pros and Cons
IS: one injection gets full coverage, but with phrenic nerve dysfunction.
SC: doesn’t get skin, but can avoid or reduce phrenic nerve dysfunction. • In elderly patients, patients with COPD, or sleep apnea, I try to reduce the risk of phrenic nerve dysfunction by using supraclavicular approach.
• To anesthetize the skin, you can block the supraclavicular branches of the cervical plexus with a subcutaneous injection above the clavicle, starting at the needle entry site from the supraclavicular block. Axillary Block
Axillary Block Brachial Brachial Plexus Sheath A sheath surrounds the brachial plexus, from the transverse processes all the way down into the axilla. Axillary Block: Anatomy
Axillary Block: Anatomy The brachial plexus has branched into the terminal nerves as it enters the axilla.
The median, radial, and ulnar nerves surround the axillary artery, within the brachial plexus sheath.
The musculocutaneous nerve exits the sheath more proximally, and enters into the coraco
brachialis muscle. Axillary Block: CrossSectional Anatomy
Axillary Block: CrossSectional Anatomy Axillary Block: CrossSectional Anatomy
Axillary Block: CrossSectional Anatomy Where are the nerves actually located?
Where are the nerves actually located? Ulnar N. Distribution
Ulnar N. Distribution Median N. Distribution
Median N. Distribution Radial N. Distribution
Radial N. Distribution Nerves Are Mobile:
Nerves Are Mobile: With pressure on the probe, the Median n. here moved around
the axillary artery. Compression of the Axillary Vein: Identifying Individual Nerves:
Identifying Individual Nerves:
Nerves can frequently be identified by: Their location in relation to the axillary artery. Change in position as one scans distally. Movement of nerve with flexion/extension at wrist and elbow.
(See examples in the following slides) The Ulnar n. lies on the anteroinferior aspect of the axillary and brachial arteries. About halfway down the arm, it diverges away from the artery, and moves more posteriorly. Ulnar Nerve in the Axilla
Ulnar Nerve in the Axilla Demonstration of ulnar nerve movement with
wrist flexion and extension. The Medial n. lies on the anterosuperior aspect of the axillary and brachial arteries. About halfway down the arm, it crosses the artery, and winds up medial to the artery in the antecubital fossa. Median N in the Axilla:
Median N in the Axilla: Demonstration of median nerve movement with
elbow flexion and extension. Anatomy: Anatomy: Radial n. Lies posterior –
inferior to axillary artery.
Moves posterior and wraps around humerus with profunda brachii a. As you move down the arm, the radial nerve has moved backwards towards the humerus. Radial Nerve in Axilla
Radial Nerve in Axilla The radial nerve moves toward the humerus as one scans
distally. The profunda artery can sometimes be seen traveling
with it. Musculocutaneous N. Anatomy:
Musculocutaneous N. Anatomy: Proximal to the axilla, the musculocutaneous nerve leaves the plexus sheath and enters into the corocobrachialis m. Musculocutaneous N in Axilla
Musculocutaneous N in Axilla The musculocutaneous n moves away from artery as you
scan distally. Step By Step Guide: Imaging
Step By Step Guide: Imaging Get US image – usually a SAX view.
Adjust depth, focus and gain of image. Step By Step Guide:
Step By Step Guide:
Identify Structures Use probe movement (compression) and color doppler to identify artery and veins. Step By Step Guide:
Step By Step Guide: Plan Your Needle Trajectories Decide what your target area is, and how to get there without hitting veins, nerves and arteries.
I usually inject 3 locations – posterior to artery, anterior to artery, and musculocutaneous (if needed). A “peri
arterial technique”. N
N Radial N. Approach
Radial N. Approach Ulnar N. Approach
Ulnar N. Approach Local injection: Median N Local injection: Median N Musculocutaneous N. Approach
Musculocutaneous N. Approach The radial, median, and ulnar nerves are seen outlined with local. Popliteal Fossa Nerve Popliteal Fossa Nerve Blocks Sciatic Nerve Origin:
Sciatic Nerve Origin: The sciatic nerve is formed from the sacral plexus, and is formed from L4,5 and S1,2,3. The roots divide into anterior (tibial) and posterior (common peroneal) divisions. Sciatic Nerve Anatomy
Sciatic Nerve Anatomy The Sciatic nerve runs posteriorly down into the popliteal fossa.
Tibial & peroneal components run in common sheath, side by side, with medial/lateral relation.
At a point 710 cm above the posterior crease, the common peroneal and tibial nerves separate. Popliteal Fossa Anatomy
Popliteal Fossa Anatomy In the popliteal fossa, the nerves lies posterolateral to popliteal artery. Note the close association between the Common Peroneal n. and the Biceps m. tendon. These pictures demonstrate how there is variability in where the sciatic divides. Popliteal Fossa Anatomy
Popliteal Fossa Anatomy Sciatic N. Cutaneous Distribution Sciatic Bone Innervation
Sciatic Bone Innervation The media and lateral plantar nerves are branches of the tibial nerve. Posterior Approach:
Posterior Approach: Lateral Approach:
Lateral Approach: Issues With Standard Techniques
Issues With Standard Techniques Variability in division of Sciatic n.
Spread issues – local doesn’t spread to adequately contact each nerve. Popliteal Fossa Ultrasound Imaging:
Popliteal Fossa Ultrasound Imaging:
Positioning: Patient prone Stand on side of block, machine on opposite side. Imaging:
Imaging: Start at crease, parallel to crease. (Nerves are at shallowest depth at this location.)
Look for tibial n, centered between muscle bellies. Posterior
Lateral Medial Try to identify the Tibial n. Posterior
Lateral Medial Posterior
Lateral Medial Posterior
Lateral Medial Fine Tuning Imaging: Slight rotational and angle adjustments of probe, to get best cross section.
Move probe cephalad to find merger point of peroneal and tibial nerves. Lateral Medial Sliding the probe cephalad. Lateral Medial Lateral Medial Another example. Try to identify Tibial and Peroneal n. components. Lateral Medial Same pateint, slightly more cephalad. Try to identify the nerves. Sonosite 180+
Sonosite 180+ Just to show how technology has advanced, here’s an image with our old US system. Sciatic Nerve Tricks
Sciatic Nerve Tricks
Lateral Medial If the patient flexes and extends foot, the sciatic nerve can be seen rotating in the popliteal fossa. Posterior Approaches: IP OOP Lateral Medial Another example. Transducer is at the level of the popliteal crease. Try to identify the anatomy. Lateral Medial Tibial n. Popliteal a. The peroneal n. can’t be definitely appreciated in this image. Lateral Medial Peroneal n. Tibial n. The probe has now been moved cephalad, and the tibial and peroneal nerves can now be seen next to each other. Lateral Medial Same patient – with in plane approach injection from the left side of the screen. The needle is not visualized, but it had been placed adjacent to the tibial n. prior to injection. Local anesthetic can be seen surrounding the sciatic branches. Approximate
trajectory Peroneal n. Tibial n. This image was taken after 40 ml of local anesthetic was injected. Local is seen surrounding both branches of the Sciatic n. The nerve was pushed away from the needle tip by the local anesthetic injection. Lateral Approach:
Lateral Approach: It is possible to image from underneath, while doing a lateral approach. However, it can be harder to image the needle with this approach. A lateral approach injection. Local is seen surrounding the nerve. Scenario:
Ankle Fracture Popliteal fossa block
Saphenous n. block vs local by surgeon, if medial incision.
GA via LMA or spinal. Conclusions:
Conclusions: We discussed rationale for US guidance.
We discussed technical aspects of US guidance.
We discussed interesting findings seen with US.
Discussed use of US in femoral, IS, SC, axillary and popliteal blocks. Resources:
Resources: www.NYSORA.com St Lukes’s, NYC http://www.usra.ca Toronto http://www.neuraxiom.com/ Excellent! http://www.dhmc.org/.... Dartmouth http://www.usgraweb.hk/ Hong Kong
Some bonus images follow. Sartorius m. Saphenous v. Approx.
Location. Cross section of the sartorius m. at a level just above the patella. Can be used to do a transsartorius approach to the saphenous nerve. Common peroneal n. Dorsalis pedis a. Cross section of anterior surface of foot, level of malleoli. Post tibial a. Tibial n. Cross section of medial aspect of foot, above medial malleolus. ...
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- Fall '11
- Anatomy, Brachial plexus, femoral nerve