Chapter 45- Brachial Plexus Nerve Blocks Flashcards
What commonly given premedication has been shown to elevate the seizure threshold for local anesthestics?
Benzodiazapines
What nerves give rise to the brachial plexus?What
C5-T1- ventral primary divisions; possible contributions from C4 and T2
After the roots, the brachial plexus branches to form what?
Superior, Middle and Inferior trunks
In the brachial plexus, after the trunks, the branches divide and form what?
Anterior and posterior divisions
In the brachial plexus, after the division, the branches form what?
The three posterior divisions form the posterior cord; upper two anterior divisions form the lateral cord, and the lower anterior division forms the medial nerve
What major nerves come from the posterior cord?
radial and axillary nerves
What major nerves come from the lateral cord?
musculocutaneous nerve and part of the median nerve
What major nerves come from the medial cord?
ulnar nerve and part of the median nerve
What is the terminal sensory branch of the musculocutaneous nerve?
lateral antebrachial nerve
What are some pulmonary function changes that occur after interscalene plexus block?
FVC and FEV1 can be reduced by 25-30%, occur within 15 minutes of injection
After interscalene block patient complains of dyspnea. What can you do?
Usually patient will have adequate respiratory function. Place patient in upright position to optimize the diaphragmatic geometry and function and increase FRC. Can obtain CXR to rule out pneumothorax.
You are doing a shoulder surgery. What are advantages and disadvantages of sitting position?
++ Seated position optimizes chest wall mechanics- increases FRC
—hypotension and increased risk of Bezold- Jarisch reflex
What is the Bezold- Jarisch reflex and what can be done to diminish it?
Paradoxical cardiac inhibition and bradycardia in response to decreased venticular volume from venous pooling in siting position. Can use IV beta blockers to diminish this resopnse
After interscalene block patient returns 1 week later with numbness and tingling of the ulnar nerve. What do you tell the patient and how would you manage this?
Because interscalene blocks often cause ulnar sparing, even with ultrasound guidance and large volume local anesthesia, and needle does not contact the nerve roots, direct injury to the ulnar nerve is exceedingly rare. May be positioning during surgery, dislocation of humeral head during or tourniquet. I would consult a neurologist if this persisted past 1 week and explained that persistent neuropathy usually resolves within 6 months.
