Principles Final - upper blocks Flashcards by Frank E

What is the purpose of regional anesthesia?

Provides site-specific, long-lasting, and effective anesthesia and analgesia

Suitable for many surgical procedures

Improves analgesia

Can have a major impact on patient satisfaction
Optimal pain relief

Less side effects (i.e., PONV)

Early mobilization

Lower costs

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What does regional anesthesia reduce?

Morbidity
Mortality
Need for reoperation

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Is the success and safety of regional anesthesia highly dependent on the accurate delivery of the correct dose of local anesthetic?

YES

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What are some risks of regional anesthesia?

Systemic toxicity
Infection
Bleeding
Permanent nerve injury

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What are some risks of regional anesthesia?

Systemic toxicity
Infection
Bleeding
Permanent nerve injury

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Where does the pre-block stage usually occur?

Blocks can be performed in the OR , but preferable to administer block in a separate room or area due to “soak time”

Time it takes local anesthetics to cross the cell membrane, block action potentials, and produce either analgesia or surgical anesthesia

All supplies should be assembled and readily available prior to beginning the block

Oxygen, monitoring equipment, emergency airway equipment, resuscitative equipment

Emergency medications
Epinephrine, Atropine, Phenylephrine, Propofol, Succinylcholine, Midazolam, Intralipid

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Do you monitor the patient at all times while doing regional anesthesia?

YES

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What are some tips about the premedication and sedation stage?

Titrated to effect for individual patient and block performed

Patient should be conscious enough to report nerve contact

Common to use a combination of several of the following drugs:
Midazolam
Fentanyl
Alfentanil
Ketamine
Propofol

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What are the two common techniques for the block performance stage?

Nerve Stimulation

Ultrasound Imaging

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Basics of Technique and Equipment of Nerve Stimulation (NS) Technique

Low-current electrical impulse is applied to a peripheral nerve

Produces stimulation of motor fibers, indicating proximity to the nerve

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What are the limitations of the nerve stimulation technique?

Inconsistent results

Variations in electrical properties of different nerve stimulators

Other variables that effect the ability to stimulate nerves:

Conducting area of the electrode (stimulating needle vs. stimulating catheter tip)

Electrical impedance of the tissues

Electrode-to-nerve distance

Current flow

Pulse duration

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Practical guidelines for nerve stimulation

NS should be set to deliver a current of 1 to 2 mA

Once the needle is inserted into the skin, the assistant should maintain constant aspiration of the syringe plunger observing for blood return in the needle tubing

The needle is in the proximity of the nerve when a motor response is seen between 0.3 to 0.5 mA

***Placing the needle where a motor response only requires 0.1 to 0.2 mA increases the risk of intraneural injection and should be avoided

Once the nerve is located, inject 2-3 cc of local anesthetic (LA) and observe for loss of motor twitch

Inject remaining medication in 5cc increments, aspirating the plunger q 5cc

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What should nerve stimulation be set to?

1 to 2 mA

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What increases the risk of intraneural injection?

Placing the needle where a motor response only requires 0.1 to 0.2 mA (The needle is in the proximity of the nerve when a motor response is seen between 0.3 to 0.5 mA)

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What are the benefits of ultrasound technique vs. nerve stimulation?

Anesthetist can adjust needle and catheter placement under direct visualization

Fewer needle attempts

Increased block success

Improved sensory and motor blocks

Reduced onset times

Prolonged block duration

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Practical guidelines for ultrasound technique

Sterile preparation of the skin and US probe

Use adequate US gel to improve structure visualization

Best to identify reliable anatomic landmarks (bone or vessel) with a known relation to the target nerve
“Trace” or follow the nerve to the optimal block location

In-plane approach to needle insertion allows for better visualization

When close to the nerve a 1-2mL test dose of D5W can be injected to visualize the spread

D5W will appear as a hypoechoic expansion and illuminate the surrounding area, improving visibility of the nerves and block needle

Steep learning curve with US technique

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When do you use a test dose of 1-2 cc’s of D5W?

For ultrasound technique. When close to the nerve a 1-2mL test dose of D5W can be injected to visualize the spread

D5W will appear as a hypoechoic expansion and illuminate the surrounding area, improving visibility of the nerves and block needle

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The in-plane technique

The needle is aligned in the plane of thin ultrasound beam allowing the visualization of the entire shaft and the tip. (YOU SEE THE WHOLE NEEDLE)

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Out of plane technique

the ultrasound beam transects the needle, and the needle tip or the shaft is observed as a bright spot in the image. (YOU JUST SEE A BRIGHT SPOT)

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Anatomic landmark for interscalene block

subclavian artery and scalene muscles

Anatomic landmark for supraclavicular block

subclavian artery

infraclavicular

subclavian/axillary artery and vein

Axillary

axillary artery

Needles Single-shot nerve block

22- to 24-gauge insulated needles with short bevels

Needles for Continuous nerve block

18- to 20-gauge needles when using a catheter-through-needle technique

Catheters

Catheter is similar to an epidural catheter 18-gauge insulated Tuohy needle with NS capability used for insertion

Discharge criteria after a block

Stable vital signs in the PACU Pain well-controlled upon discharge Advise patient of risks associated with an anesthetized limb Potential for pressure neuropathies Risk of burns when cooking

What is an absolute contraindication for any block?

PATIENT REFUSAL Absolute contraindications include patient's refusal, local infection, active bleeding in an anticoagulated patient, and proven allergy to local anesthetic. Other contraindications: Local infection Systemic anticoagulation Schizophrenic patients should receive PNB accompanied by general anesthesia Existing neurologic deficits (*potential contraindication) Clear and thorough documentation of current neurologic deficits prior to block performance

Is local anesthetic concentration dependent?

Yes

How does nerve damage occur with blocks?

May result from intraneural injection

What are the types of upper extremity blocks?

Brachial Plexus Blocks: Interscalene Supraclavicular Infraclavicular Axillary Radial Nerve Blocks Ulnar Nerve Block Median Nerve Block

Where does the brachial plexus arise from?

The anterior primary rami of C5-C8 and T1 spinal nerves. Plexus consists of 5 roots, 3 trunks, 6 divisions (2 per trunk), 3 cords, and 5 major terminal nerves

Axillary nerve

Originates C5-C6 Posterior cords

Radial nerve

C5-C8 and T1 roots Upper and middle trunks Posterior divisions Posterior cords

Median nerve

C5-C8, T1 All trunks Lateral and medial cords

Musculocutaneous nerve

C5-C7 roots Upper and middle trunks Anterior divisions Lateral cord

Ulnar nerve

C7-C8, T1 Lower trunk Anterior division Medial cord

What is the indication for axillary block?

Surgery distal to the elbow

What are the contraindications to axillary block/

Local infection Neuropathy Bleeding risk

Indication for interscalene block?

Indicated for surgical procedures involving the shoulder and the upper arm Roots C5-C7 are most densely blocked with this approach The ulnar nerve originating from C8-T1 may be spared *NOT appropriate for surgery at or distal to the elbow

Contraindications to interscalene block

Local infection Severe coagulopathy Local anesthetic allergy Patient refusal

Indication for Supraclavicular Block

Dense anesthesia of the brachial plexus for surgical procedures at or distal to the elbow

Issues with supraclavicular block

Historically, the block fell out of favor due to the high incidence of complications that occurred with paresthesia and nerve stimulator techniques. Ultrasound guidance has improved its safety and increased its current use.

Indication for intraclavicular block

Brachial plexus block at level of cords For surgical procedures at or distal to the elbow The intercostobrachial nerve is spared (T2 dermatome)

Most common sites for terminal nerve blocks

elbow and the wrist are the most common sites

Intravenous Regional Anesthesia (Bier Block)

Indications: Surgical procedures of short duration (45-60 minutes) Trigger finger release Carpal tunnel release