Blocks of the proximal arm and thorax.

The procedures and techniques we will discuss this week have a lot more risk than other blocks. Keep this in mind when you are choosing a technique and consenting your patient.

Drug	Class	Onset	Duration of Action*	Conc/Dose per 10 ml	Max Dose WITHOUT Epi
Procaine	Ester	5 min	15-90 min	2% - 200 mg/10ml	8 mg/kg
Tetracaine	Ester	7 min	120-240 min	0.5% - 50 mg/10ml	1.5 mg/kg
Bupivacaine	Amide	2-10 min	120-240 min	0.5% - 50 mg/10ml	1.5mg/kg
Lidocaine	Amide	<1 min	30-120 min	1% - 100 mg/10 ml 2% - 200 mg/10 ml	4.5 mg/kg
Mepivacaine	Amide	3-20 min	30-120 min	1.5% - 150 mg/10 ml	5 mg/kg
Ropivacaine	Amide	15 min	120-360 min	0.5% - 50 mg/10ml	3 mg/kg

Considerations with nerve blocks:

Drug choice – allergies, duration of action, use of epinephrine, dose/toxicity
Location – nerves and blood vessels like to run together – ALWAYS aspirate prior to injecting
Exam – for patients where a subspecialist will need an accurate exam (ortho, neurosurgery/neuro), you may need to coordinate timing of a block to avoid confounding important exam findings. Let your nurses/consultants know what you did so they do not activate a stroke alert.
Always document how much local anesthetic was given and of what concentration

General Consent

BLOCK SPECIFIC RISKS ARE DETAILED BELOW

Risks: bleeding, infection, swelling of injection site, nerve injury, pain, failure of block to work, damage to surrounding structures, systemic toxicity, arrhythmias, unexpected spread of medication. Because the brachial plexus are larger nerves, these carry a higher risk of direct trauma to the nerve from the needle, nerve sheath trauma, direct/permanent neurotoxicity from the anesthetic on the nerve. Most of the more proximal brachial plexus nerve blocks carry risk of phrenic nerve palsy, which can decrease respiratory function by 30% and may not be tolerated by patient with decreased resp function at baseline.
- Local anesthetic toxicity can occur with injection into the vasculature – symptoms include confusion, headache, dizziness, tremors, hemodynamic instability, arrythmias including VT/VF, EKG may show prolonged PR and/or QRS
  - Treat with intralipid 20% solution – 1.5 ml/kg IV given over a minute, can be repeated x 2 if needed, may need to start a drip if persistent signs of toxicity
- Alternatives: systemic analgesics, general anesthesia, topical agents like LET/EMLA
- Contraindications: coagulopathy, overlying cellulitis, unable to safely access nerve due to anatomic considerations, uncooperative patient.

Supplies:

Chlorhexidine/alcohol/povidone to clean skin
Syringe (usually 3, 5, or 10 ml)
18 ga blunt tip syringe to draw up
27 or 30 ga needle for injecting
- Spinal needles can work well for deeper injections
Your local anesthetic of choice +/- sodium bicarbonate
Ultrasound

Blocks in the thorax can be broken down into a few different groups. The first is brachial plexus blocks – these are useful for pain relief in the shoulder, upper chest, and larger areas in the arm. Paravertebral and intercostal blocks can be used for localized chest wall pain. Plane blocks may be helpful for pain relief of larger areas of the chest wall, but the use is controversial in the anesthesia literature and the pain relief is highly variable. Ultrasound should be used for ALL thoracic blocks given the high risk and important nearby structures. Do not inject if you feel high pressure/resistance to avoid intrafascicular injections and permanent nerve damage. Most of these blocks are in highly vascular areas – keep this in mind when advancing your needle and injecting.

Block	Area anesthetized	Landmarks/US Probe Positioning	Positioning	Location Specific Risks	Pictures
Interscalene	Shoulder, upper arm, lateral clavicle	Scan laterally on the anterior neck between the level of the cricoid cartilage to the supraclavicular fossa. Nerve roots for C5-6 will appear as hypoechoic round structures between the anterior and middle scalene.	Supine with face turned towards contralateral shoulder	Diaphragmatic paralysis – up to 45% of patients, pneumothorax, recurrent laryngeal nerve blockade (hoarseness, laryngeal hyperemia), Horner’s syndrome, epidural or spinal spread resulting in spinal/epidural anesthesia, inadvertent vertebral artery injection, direct/needle related damage to the cervical spinal cord
Supraclavicular	Mid-humerus to the fingertips	Start with the US probe just caudad to the mid-clavicle – use color doppler due to multiple arteries passing through brachial plexus at this level Needle should not be inserted more than 1 cm in depth to avoid puncturing important structures Inject small volumes of anesthetic	Supine with face turned towards contralateral shoulder	Significant risk of phrenic nerve palsy – in ½ to 2/3 of patient will experience. Intravascular injection, pneumothorax, recurrent laryngeal nerve blockade (hoarseness, laryngeal hyperemia), Horner’s syndrome, epidural or spinal spread resulting in spinal/epidural anesthesia
Infraclavicular	Arm, forearm, hand	Place linear probe in the para sagittal plane at the lateral clavicle. Needle insertion site is 2 cm medial and 2 cm inferior to the coracoid process. Identify the axillary artery – the brachial plexus cords will be hyperechoic structures near the artery. The cords can be difficult to ID, but the block can be done without clear cords. Inject into the area around the axillary artery – the plexus cords are inferior to the artery. Aspirate every 5 ml to ensure needle has not moved into the artery. Usual needle depth to reach target is 4-5 cm.	Supine with face turned towards contralateral shoulder, arm abducted to 90 degrees and elbow flexed to help raise the clavicle	Pneumothorax, intraarterial injection, damage to axillary artery, hematoma. Lower risk of recurrent laryngeal nerve blockade, Horner syndrome, and phrenic nerve block.
Axillary	Forearm, hand	Palpate the axilla to find the point where the pectoralis inserts on the humerus. Place US probe at this spot. Scan slightly proximally to identify the axillary artery. The median, ulnar, and radial nerves are located around the axillary artery and should be readily identified. Direct needle inferior and posterior – deposit anesthetic posterior to the artery first. Will likely require pulling needle back and redirecting to inject at multiple sites to anesthetize all the nerves.	Supine with arm abducted to 90 degrees. Do not over abduct – this can put tension on the brachial plexus	High risk for inadvertent intrafascicular injection or damage to the nerve by the needle tip. Very low risk for phrenic nerve involvement or pneumothorax.

Non-Brachial Plexus Blocks

A few comments about the next two blocks. Both may be useful for pain control with rib fractures or other chest wall trauma. The area where the local anesthetic is injected tends to be highly vascular, so the anesthetic will be washed out of the tissue quickly. Short acting anesthetics will be less useful here. Both will result in blockade along a dermatomal distribution, so you will likely need to anesthetize at multiple levels above and below the dermatome(s) of concern to achieve adequate pain control. Paravertebral blocks have the added issue of potential spread proximally into the CNS.

Pneumothorax is a potential complication, but in general these patients can be placed on oxygen and observed unless unstable. Do not do bilateral blocks for this reason – those patients would likely benefit from an epidural or spinal anesthesia rather than a local block.

Block

Area anesthetized

Landmarks/US Probe Positioning

Positioning

Location Specific Risks

Pictures

Paravertebral block

Dermatomal distribution, blockade of somatic and sympathetic nerve. Area anesthetized depends on how many levels are injected.

Target is a wedge-shaped space on either side of the vertebral column bounded by the vertebral body, the transverse process, and the parietal pleura/endothoracic fascia. Area communicates upward and anteriorly into other nerve spaces and into the retroperitoneal space.

Mark the spinous processes on the back. The target area is 2.5 cm lateral to the spinous process. When inserting needle, the goal is to hit the transverse process and then walk the needle off the superior aspect of the TP (usually at 3-4 cm in depth). Do not insert more than 4 cm – consider using a needle with depth markings to prevent going too deep.

US can be used to identify the pleural lining to avoid going too deep

Patient should be seated to allow palpation of relevant anatomy over the spine.

Significant risk for pneumothorax and pleural puncture, vessel puncture with damage/hematoma formation

Can cause epidural/spinal anesthesia or get into the subdural and intrathecal spaces.

Hypotension can be caused by sympathetic blockade and/or epidural anesthesia

Intercostal block

Dermatomal

Landmarks are along the inferior aspect of the rib, in line with the tip of the scapula.

Nerve is located inferior to the rib. Vein is most superior structure, artery lies underneath, and nerve is the most inferior (VAN). Nerve is not enveloped so tends to be easily anesthetized. If using landmarks – insert needle at 20% from perpendicular to rib space. Us guidance can decrease risk of pleural injury/pneumothorax

Sitting up, slightly leaning/flexed forward

Pneumothorax, inadvertent pleural damage, injury to neurovascular bundle.

Area is highly vascular, and local anesthetic is readily taken up by intercostal vasculature (regardless of whether epi is used) – higher risk for local anesthetic toxicity

Thoracic fascial plane blocks

Plane blocks are a relatively new technique developed in the last decade or so. They work by basically hydrodissecting between the fascial plane layers with enough anesthetic to block any nerves that sit within that fascial layer. Unfortunately, the relief is highly variable and requires deposition of large volumes of anesthetic. Anesthesia literature on the blocks is somewhat mixed but they have become more widely used recently with more emphasis on opiate sparing pain control. There are multiple thoracic plane blocks:

Because these are still being debated within the world of anesthesia, we will not discuss them in depth here. If you are interested, these articles have more information and techniques:

https://associationofanaesthetists-publications.onlinelibrary.wiley.com/doi/10.1111/anae.15276

https://www.eajm.org/Content/files/sayilar/224/15.pdf

https://www.youtube.com/watch?v=ccQ7st_fFQ8 – this is a little bit longer video about the mechanisms of fascial plane blocks

https://www.youtube.com/watch?v=fDSuwyQULlA – discussion of several thoracic/abd plane block techniques

https://www.youtube.com/watch?v=62WxSa3kJ0c – US guided thoracic plane blocks (in the context of cardiac surgery)

Reference:

https://www.nysora.com/pain-management/ultrasound-guided-upper-extremity-blocks/

Videos:

https://www.youtube.com/watch?v=5_EKD83UvNY – interscalene block

https://www.youtube.com/watch?v=m3GU11ZRzGc – supraclavicular block

https://www.youtube.com/watch?v=YOOoNT27Irg – supraclavicular block

https://www.youtube.com/watch?v=ui3Nip9fif8 – superior trunk block – more distal block that decreases risk of phrenic nerve involvement

https://www.youtube.com/watch?v=Uk-2pdFQ75A – infraclavicular block

https://www.youtube.com/watch?v=_WqJpAIcCgs – infraclavicular block

https://www.youtube.com/watch?v=3MBmUFMoH7w – US guided axillary block (NOT axillary nerve)

https://www.youtube.com/watch?v=rG7PXuXrqbU – axillary block

https://www.youtube.com/watch?v=D92ZbS8fMY0 – paravertebral block

https://www.youtube.com/watch?v=WMuwfOqSRro – US guided paravertebral block

https://www.youtube.com/watch?v=m--qyUUzH5U – intercostal block