Ultrasound

Question 1

Field depth < 2.0 cm

Answer 1

Wrist, ankle block

Question 2

Field depth 2- 3 cm

Answer 2

Interscale ( LA anesthetic around the root or trunk of brachial plexus at the level of C6 in between the scalene muscle )
Axillary Brachial plexus block

Question 3

Field depth 3- 4 cm

Answer 3

Femoral
Supraclavicular
Tranversus abdominis plane block

Question 4

Field depth 4-7 cm

Answer 4

Infraclavicular ( cords and terminals )
Popliteal
Subgluteal sciatic nerve block

Question 5

Field depth 7.0 cm 10.0 cm

Answer 5

Pudendal block
Gluteal sciatic nerve ( subgluteal is 4-7cm )
Lumbar plexus block

Question 6

Field depth > 10.cm

Answer 6

Anterior approach to sciatic nerve

Question 7

Gain

Answer 7

Brightness

Question 8

Two function button of Gain

Answer 8

Gain and TGC ( Time-gain compensation )

Question 9

Excessive or Inadequate gain

Answer 9

The boundaries of the tissues get blurry

You lose information

Question 10

Optimal gain for peripheral nerve

Answer 10

The gain at which Best contrast that you get between the muscle and the adjacent connective tissue
You want a nice contrast between the muscle and the adjacent connective tissue !

Question 11

ASRA Recommendations

Answer 11

1- visualize : muscle, fascia , bones and blood vessels
2- ID the nerve or plexus on shot-Axis with depth set at 1 cm deep to target nerve
3- Confirm normal anatomy and recogonize variations ..we don’t all have the same body!!
4- Chose the safest most effective needle approach
5- Aseptic needle insertion technique
6- Follow the needle in real time live as you advance it toward the target
7- Secondary stimulation technique , ex: nerve stimulator
8- Needle tip in the correct position ? Inject Small volume of test solution
9- Adjust your needle as necessary for optimal perineural LA spread
10- Safety: Aspiration, monitoring , patient response, assessment, resistance to injection

Question 12

US machine set up on which side of patient

Answer 12

Opposite side

Question 13

Needle selection for Peripheral nerve block

Answer 13

Large bore 17G: easily visualized directed under US -deep blocks -i.e Infraclavicular when needle in steep (>45) angle .
Smaller bored 22 G: More diff to see , but still easily visualized in superficial blocks i.e. Axillary block when needle angle is shallow PLUS more comfortable for awake patient

Question 14

Insulated needle is what exactly ?

Answer 14

Electrical current is concentrated at the needle tip and a wire attached to the needle hub connects to a nerve stimulator .
Used for 1) accurately ID specific nerve = improve adequacy of block .

Question 15

What is Peripheral Nerve Stimulation via insulated needle ?

Answer 15

Method of using low intensity electric current ( 0-5mA current at a set 1-2 Hz interval) to elicit a response/muscle twitch .
When an insulated needle close to to a motor nerve = muscle contraction

Question 16

How is the circuit completed in Insulated needle PNS?

Answer 16

Ground electrode is attached to the patient to complete the circuit

Question 17

Needle technique for US . What is the position and what is visualized ?

Answer 17

Position -Inline and parallel to transducer

Both shaft and tip are seen

Question 18

Transducer prep

Answer 18

Sterile sheath
Gel inside sheath
Smooth sheath cover over transducer = no wrinkles that can impede full contact
Rubber band = transducer can’t move inside sheath
Lots of sterile gel to skin

Question 19

Peripheral nerve block technique

Answer 19

2 person: get an assistant !
Monitors : BP, EKG, Pulse ox
OXYGEN/SUCTION/EMERGENCY MEDS / CRASH CART/ INTRALIPID
Make sure your nerve stimulator and your connecting cables work before starting
Premedicate but DON’t OVERSEDATE = benzo/opioid for comfort but pt should always be able to respond to verbal cues
Proper patient position = favorable for clinician and comfy for patient

Question 20

Negative pole vs Positive Pole location

Answer 20

Negative pole connected to the needle N-N
Positive pole connected to the Pt Skin P- S
Negative - Needle
Positive - Skin

Question 21

You have started set for the block , start the procedure ..

Answer 21

1 Time -Out
2 Disinfect skin - sterile field
3 Connect the PNS needle to the nerve stimulator- only turn it on after in subQ tissue = before will cause pain then Deliver 2 mA!!
Apply gel to transducer
Position transducer on skin- always keep within sterile field
Introduce needle / start procedure !

Question 22

You introduced the PNS needle in SubQ now what ?

(Slide 23)

Answer 22

Once the muscle you are looking for is obtained reduce 1)current 2) intensity and 3)amplitude GRADUALLY and advance needle SLOWLY

Question 23

When is Optimal LA injection reached ?

Answer 23

When muscle contraction is maintained at a current between 0.2 - 0.5 mA
<0.2mA eliciting muscle contraction= increased risk of intraneural injection = neural damage!