Principles Final - upper blocks Flashcards
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
What does regional anesthesia reduce?
Morbidity
Mortality
Need for reoperation
Is the success and safety of regional anesthesia highly dependent on the accurate delivery of the correct dose of local anesthetic?
YES
What are some risks of regional anesthesia?
Systemic toxicity
Infection
Bleeding
Permanent nerve injury
What are some risks of regional anesthesia?
Systemic toxicity
Infection
Bleeding
Permanent nerve injury
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
Do you monitor the patient at all times while doing regional anesthesia?
YES
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
What are the two common techniques for the block performance stage?
Nerve Stimulation
Ultrasound Imaging
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
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
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
What should nerve stimulation be set to?
1 to 2 mA
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)
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
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
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
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)
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)
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
More on bier block (IV regional)
Technique:
IV Catheter is inserted on the dorsum of the surgical hand
A double pneumatic tourniquet is placed on the arm
The extremity is elevated and exsanguinated by tightly wrapping an Esmarch elastic bandage from distal to proximal direction
The distal tourniquet is inflated, then the proximal tourniquet is inflated.
Esmarch bandage removed, and 50 mL 0.5% preservative free lidocaine is injected over 2-3 minutes through the IV catheter which is subsequently removed
Anesthesia is usually established after 5-10 minutes
Tourniquet pain usually develops in 20-30 minutes at which time the distal tourniquet can be deflated
Once the distal tourniquet is re-inflated, the proximal tourniquet can be deflated to allow for drift of the LA under the tourniquet thereby reducing tourniquet pain
The tourniquet must remain inflated for at least 20 minutes to prevent LA toxicity
Slow “cycling” tourniquet deflation can reduce the risk of LA toxicity
Ask the patient if they are experiencing a metallic taste in their mouth or ringing in their ears. If they are, keep O2 and monitors on the patient and continue to monitor until it subsides.
Which block is NOT appropriate for surgery at or distal to the elbow?
interscalene block
Which block fell out of favor due to paresthesias but has been utilized more since ultrasound?
supraclavicular
