Upper Ext Blocks Flashcards
Advantages of peripheral nerve block
Potent analgesia
Reduction in stress response
Reduction in systemic analgesia requirement
Reduction in opioid-related side effects
Reduction in general anesthesia requirement
Decrease the incidence/occurrence of chronic pain
Regional anesthesia is often favored in pts with
multiple comorbidities for whom a general anesthetic carries a greater risk.
T/F - Periph nerve blocks last longer than spinals
True
Pt. cooperation and participation are key to the success and safety of every regional anesthetic/procedure. What pt populations would be at increased risk for complications?
Pts. who are unable to remain still may be exposed to increased risk - younger pts., developmentally delayed individuals, dementia, movement disorders.
No regional block if platelets < _____ and pt/aptt >_____
100,000
2X normal
Never inject through infected tissue, what will happen to your block of you do?
you can tract infection
there will be more unionized medication and it won’t work as well
Pts with pre-existing nerve injuries may pose a risk or contraindication - what should you do before you place a block?
Make sure you document prior existing nerve injury BEFORE you place block incase you cause damage or so the patient cant say caused it
T:F - Peripheral neuropathy or previous nerve injury may have a higher incidence of complications
True, could have prolonged sensory block
What should you do if you get LAST
Call for help - code blue
CPR
Lipid emulsion administration to sequester the LA - intralipid 20% 1.5ml/kg/min bolus, max 8ml/kg
Preparation for cardiopulmonary bypass
What happens when you mix epi with LA?
prolongs duration
How long can bupivocaine and ropivicaine have effects for?
up to 12-18 hrs
Lidocaine
2% = ___ mg/ml
0.5% = ____ mg/ml
0.25% = ____mg/ml
2% = 20mg/ml
- 5% = 5mg/ ml
- 25% = 2.5mg/ml
How do you determine the concentration of epi if you are given:
EPI 1:200,000
divide 1 million by second number
1,000,000/200,000 = 5mcg/ml
If I have 3cc Lido 1.5 % with 1:200,000 Epi, what are my concentrations?
Lido
1.5% = 15mg/ml X 3cc = 45 mg
Epi
1 mil/200,000 = 5 X3 cc = 15 mcg
What standard hemodynamic monitors should be on for a block?
BP and pulse Ox
have O2 nearby
Placing blocks is a ____ _____ technique
strick sterile
What is a field block technique
A local anesthetic injection that targets terminal cutaneous nerves
Commonly used by surgeons to minimize incisional pain
Dentist
Why can a field block be undesirable?
Undesirable when block may obscure the operative anatomy or where local tissue acidosis (ie. Infection) prevents effective local anesthetic function
What is the paresthesia technique?
Practitioner uses known anatomic relationships and surface landmarks as a guide
Block needle is inserted in proximity of the target nerve or nerve plexus
When needle makes direct contact with a sensory nerve, a paresthesia is elicited and the LA is injected
What is the nerve stimulation technique?
When the insulated needle is placed in proximity to a motor nerve, muscle contractions are induced.
For nerve stimulation technique, It is common to redirect the block needle until muscle contractions occur at a current less than
0.5 mA
For nerve stimulation technique, what does 0.5mA mean?
Lets me know I am close to the nerve
Usually start around 2
If I lose signal, going away from nerve
Some thought that a muscle contraction elicited at less than 0.2 mA implies
intraneural needle placement
What is the ultrasound technique?
Ultrasound for peripheral nerve location and subsequent block
high-frequency sound waves emitted from piezoelectric crystals that travel at different rates through tissues of different densities, returning a signal to the transducer.
1-20 MHz
What is Echogenicity
the degree of efficiency with which sound passes through a substance
Hypoechoic
Hyperechoic
Anechoic
What is Hypoechoic
structures and substances through which sound easily passes. Appear DARK or BLACK on the ultrasound screen.
solid organs, deep structures
What is Hyperechoic
structures reflecting more sound waves appear BRIGHTER, “WHITE” on the ultrasound screen.
diaphragm, gallstones, bone, pericardium
What is Anechoic
no reflection
fluid and blood filled structures
What does muscle look like on an ultrasound?
striations
T/F: nerve bundles can bee hyper or hypoechoic?
TRUE
Linear probe - a high frequency transducer that offers a high resolution picture with
less tissue penetration.
What is a linear probe good for?
Good for superficial nerves
Provide undistorted image
First choice among practitioners
Curvilinear probe - a low frequency transducer that offers better tissue penetration with
lower resolution, or poorer image quality.
What is a curvilinear probe good for?
Good for deeper structures
The optimal transducer varies depending on the ____ of the target nerve and ___ _____ of the needle relative to the transducer.
depth
approach angle
Nerves are best imaged in
cross section (short axis)
What is the characteristic appearance of nerves?
honeycomb
bundle of grapes
In-plane needle alignment (longitudinal, long-axis): In-plane needle alignment refers to aligning the needle with the long-axis of the transducer (along the ultrasound beam) so that the ______________________. One of the disadvantages of the in-plane needle view is that, it is easy to lose the image with a slight movement of the transducer as the ultrasound beam is thin. This technique requires excellent hand-eye coordination.
entire shaft and tip of the needle are visible