Chapter 33 Continuous Peripheral Nerve Blocks

Question 1

continuous peripheral nerve block (CPNB)— also called “perineural local anesthetic infusion”

Answer 1

involves the percutaneous insertion of a catheter directly adjacent to the peripheral nerve(s) supplying the surgical site

Question 2

Patients who should receive CPNB

Answer 2

CPNB is usually provided to patients expected to have at
least moderate postoperative pain of a duration greater
than 24 hr that is not easily managed with oral opioids.

Question 3

In general, axillary, cervical
paravertebral (CPVB), infraclavicular, or supraclavicular
infusions are used for surgical procedures involving

Answer 3

the hand, wrist, forearm, and elbow; interscalene, CPVB

Question 4

intersternocleidomastoid catheters are used for surgical

procedures involving

Answer 4

the shoulder or proximal humerus;

Question 5

thoracic paravertebral catheters are used for breast or
thorax procedures; psoas compartment catheters are used
for

Answer 5

hip surgery

Question 6

fascia iliaca, femoral, and psoas compartment catheters are used for

Answer 6

knee or thigh procedures;

and popliteal

Question 7

subgluteal catheters are used for surgical procedures of the

Answer 7

leg, ankle, and foot

Question 8

an interscalene catheter for

Answer 8

shoulder or proximal

humerus procedures;

Question 9

infraclavicular catheter for more

distal procedures of the

Answer 9

upper extremity;

Question 10

a transabdominal
plane catheter for inguinal or lower abdominal procedures;
a femoral catheter for

Answer 10

knee surgery

Question 11

a popliteal-sciatic catheter for

Answer 11

foot/leg procedures.

Question 12

For ultrasound-guided procedures, the term “long axis

Answer 12

used when the length of a nerve is within the ultrasound

beam

Question 13

For ultrasound-guided procedures “short axis”

Answer 13

when viewed in cross section.

Question 14

in plane,”

Answer 14

A needle inserted with its length within a two dimensional

ultrasound beam

Question 15

out of plane

Answer 15

a needle inserted across a two-dimensional ultrasound

beam

Question 16

multiple benefits of the needle in-plane, nerve

in short-axis approach

Answer 16

practitioners may learn
only one technique because it may be used for both single injection and catheter insertion procedures. it may be used for nearly all anatomic catheter locations, even for deeper target nerves.
If a 17- or 18-gauge needle
is used, the needle tip may be more-easily identified and
remains within the ultrasound plane due to its rigidity
compared with smaller gauge needles.

Question 17

The potential benefits of

using a larger needle gauge

Answer 17

(fewer needle passes given the
relative ease of keeping a rigid, larger-gauge needle in plane; less risk of undesired tissue contact due to misinterpretation of the needle shaft for the needle tip) must be
weighed against the potential risks (increased patient
discomfort; increased tissue trauma; increased injury if a
vessel is punctured)

Question 18

disadvantages of the needle in-plane, nerve in short-axis approach

Answer 18

new needle entry sites relative to the nerve compared
with more traditional nerve stimulation modalities
that typically use a parallel needle-to-nerve insertion; challenges keeping the needle shaft in-plane; difficult needle tip visualization for relatively deep nerves; and, as noted above, the catheter tip may bypass the target nerve given the perpendicular orientation of the needle and nerve.

Question 19

Needle Out-of-Plane, Nerve in Short-Axis Approach: potential benefits

Answer 19

generally familiar parallel needle-to-nerve trajectory used
with traditional nerve stimulation techniques (and also vascular access); and because the needle is parallel to the target nerve, the catheter theoretically may remain in closer proximity to the nerve, even when threaded more than a centimeter past the needle tip

Question 20

Needle Out-of-Plane, Nerve in Short-Axis Approach: disadvantage

Answer 20

the relative inability to
visualize the advancing needle tip, which some speculate increases the likelihood of unwanted contact with nerves, vessels, peritoneum, pleura, or even meninges

Question 21

The majority of perineural infusion publications have involved

Answer 21

bupivacaine (0.1–0.25%) or ropivacaine (0.1–0.4%)

Question 22

The main determinant of CPNB effects

Answer 22

local anesthetic concentration and volume or simply total drug dose. although there is evidence that for continuous posterior lumbar plexus blocks, local anesthetic concentration and volume do not influence nerve block characteristics, suggesting that local anesthetic dose (mass) is the primary determinant of perineural infusion effects.

Question 23

For procedures resulting in at least moderate postoperative

pain,

Answer 23

a basal infusion optimizes benefits such as analgesia

and sleep quality.

Question 24

Providing patients with the ability to self-administer local anesthetic doses increases perioperative benefits such as

Answer 24

improving analgesia, minimizing supplemental opioids, and allowing a decreased basal infusion
rate which minimizes the risk of limb weakness and
maximizes the infusion duration for ambulatory patients with a finite local anesthetic infusion pump reservoir volume.

Question 25

successful analgesia with CPNB using the following with

Answer 25

long-acting local
anesthetics: basal rate of 4 to 8 ml/hr, bolus volume of 2 to
5 ml, and lockout duration of 20 to 60 min

Question 26

CPNB-related complications

Answer 26

Nerve injury is a recognized complication following
placement of both single-injection and CPNB, presumably related to needle trauma and/or subsequent local
anesthetic/adjuvant neurotoxicity

Question 27

use of ultrasound decrease CPNB-related complications

Answer 27

the use of ultrasound will improve catheter insertion success rates Ultrasound also decreases other risks as well, such as vascular puncture (reported between 0% and 11% with nerve stimulation), perineuraxis catheter placement, as well as intravascular and intraneural
catheter insertion. Prolonged Horner’s syndrome due to neck hematoma is a rare complication

Question 28

The most common complication during perineural infusion

Answer 28

simply inadvertent catheter dislodgement

0–30%

Question 29

Effort to optimally secure the catheter

Answer 29

Measures have included the use of sterile liquid adhesive
(e.g., benzoin), sterile tape (e.g., Steri-Strips), securing
of the catheter–hub connection with either tape or specifically designed devices (e.g., Statlock), subcutaneous
tunneling of the catheter and the use of 2-octyl
cyanoacrylate glue

Question 30

complications

occurring during infusion

Answer 30

phrenic nerve
block and ipsilateral diaphragm dysfunction during interscalene
CPNB, local anesthetic toxicity (incredibly rare),
and infection.

Question 31

potential CPNB complications,

Answer 31

catheter knotting
(do not pass the catheter >5 cm past the needle tip), retention (with the Arrow Stimucath), and shearing (do not withdraw the catheter back into the needle unless the design
is approved for this maneuver).