Practice Guidelines

Practice Guidelines for the Prevention, Detection, and Management of Respiratory Depression Associated with Neuraxial Opioid Administration

 Summary of Recommendations

I. Identification of Patients at Increased Risk of Respiratory Depression

* The anesthesiologist should conduct a focused history and physical examination before administering neuraxial opioids.

○ Particular attention should be directed toward signs, symptoms, or a history of sleep apnea, coexisting diseases or conditions (e.g., diabetes, obesity), current medications (including preoperative opioids), and adverse effects after opioid administration.

○ A physical examination should include, but is not limited to, baseline vital signs, airway, heart, lung, and cognitive function.

II. Prevention of Respiratory Depression after Neuraxial Opioid Administration

* Noninvasive positive-pressure ventilation

○ Patients with a history of sleep apnea treated with noninvasive positive airway pressure should be encouraged to bring their own equipment to the hospital.

* Drug selection

○ Single-injection neuraxial opioids may be safely used in place of parenteral opioids without altering the risk of respiratory depression or hypoxemia.

○ Single-injection neuraxial fentanyl or sufentanil may be safe alternatives to single-injection neuraxial morphine.

○ When clinically suitable, extended-release epidural morphine may be used in place of intravenous or conventional (i.e., immediate-release) epidural morphine, although extended monitoring may be required.

○ Continuous epidural opioids are preferred to parenteral opioids for anesthesia and analgesia for reducing the risk of respiratory depression.

○ When clinically suitable, appropriate doses of continuous epidural infusion of fentanyl or sufentanil may be used in place of continuous infusion of morphine or hydromorphone without increasing the risk of respiratory depression.

○ Given the unique pharmacokinetic effect of the various neuraxially administered opioids, appropriate duration of monitoring should be matched with the drug.

○ Neuraxial morphine or hydromorphone should not be given to outpatient surgical patients.

* Dose selection

○ The lowest efficacious dose of neuraxial opioids should be administered to minimize the risk of respiratory depression.

○ Parenteral opioids or hypnotics should be cautiously administered in the presence of neuraxial opioids.

○ The concomitant administration of neuraxial opioids and parenteral opioids, sedatives, hypnotics, or magnesium requires increased monitoring (e.g., intensity, duration, or additional methods of monitoring).

III. Detection of Respiratory Depression

* All patients receiving neuraxial opioids should be monitored for adequacy of ventilation (e.g., respiratory rate, depth of respiration [assessed without disturbing a sleeping patient]), oxygenation (e.g., pulse oximetry when appropriate), and level of consciousness.##

* Single-injection neuraxial lipophilic opioids (e.g., fentanyl)

○ Monitoring should be performed for a minimum of 2 h after administration.

○ Continual (i.e., repeated regularly and frequently in steady rapid succession***) monitoring should be performed for the first 20 min after administration, followed by monitoring at least once per hour until 2 h has passed.

○ After 2 h, frequency of monitoring should be dictated by the patient’s overall clinical condition and concurrent medications.

* Continuous infusion or patient-controlled epidural analgesia (PCEA) with neuraxial lipophilic opioids

○ Monitoring should be performed during the entire time the infusion is in use.

○ Monitoring should be continual for the first 20 min after initiation, followed by monitoring at least once per hour until 12 h has passed.

○ From 12 to 24 h, monitoring should be performed at least once every 2 h.

○ After 24 h, monitoring should be performed at least once every 4 h.

○ After discontinuation of continuous infusion or PCEA with neuraxial lipophilic opioids, frequency of monitoring should be dictated by the patient’s overall clinical condition and concurrent medications.

* Single-injection neuraxial hydrophilic opioids (e.g., morphine, not including sustained- or extended-release epidural morphine)

○ Monitoring should be performed for a minimum of 24 h after administration.

○ Monitoring should be performed at least once per hour for the first 12 h after administration, followed by monitoring at least once every 2 h for the next 12 h (i.e., from 12 to 24 h).

○ After 24 h, frequency of monitoring should be dictated by the patient’s overall clinical condition and concurrent medications.

* Continuous infusion or PCEA with neuraxial hydrophilic opioids

○ Monitoring should be performed during the entire time the infusion is in use.

○ Monitoring at least once every hour should be performed for the first 12 h after initiation, followed by monitoring at least once every 2 h for the next 12 h.

○ After 24 h, monitoring should be performed at least once every 4 h.

○ After discontinuation of continuous infusion or PCEA, frequency of monitoring should be dictated by the patient’s overall clinical condition and concurrent medications.

* Sustained- or extended-release epidural morphine

○ Monitoring at least once every hour should be performed during the first 12 h after administration, and at least once every 2 h for the next 12 h (i.e., from 12 to 24 h).

○ After 24 h, monitoring should be performed at least once every 4 h for a minimum of 48 h.

* Increased monitoring (e.g., intensity, duration, or additional methods of monitoring) may be warranted in patients at increased risk of respiratory depression (e.g., unstable medical condition, obesity, obstructive sleep apnea,††† concomitant administration of opioid analgesics or hypnotics by other routes, extremes of age).

IV. Management and Treatment

* Supplemental oxygen

○ For patients receiving neuraxial opioids, supplemental oxygen should be available.

○ Supplemental oxygen should be administered to patients with altered level of consciousness, respiratory depression, or hypoxemia and continued until the patient is alert and no respiratory depression or hypoxemia is present.

○ Routine use of supplemental oxygen may increase the duration of apneic episodes and may hinder detection of atelectasis, transient apnea, and hypoventilation.

* Reversal agents

○ Intravenous access should be maintained if recurring respiratory depression occurs.

○ Reversal agents should be available for administration to all patients experiencing significant respiratory depression after neuraxial opioid administration.

○ In the presence of severe respiratory depression, appropriate resuscitation should be initiated.

* Noninvasive positive-pressure ventilation

○ Noninvasive positive-pressure ventilation may be considered for improving ventilatory status.

○ If frequent or severe airway obstruction or hypoxemia occurs during postoperative monitoring, noninvasive positive-pressure ventilation should be initiated.

source: Anesthesiology:February 2009 - Volume 110 - Issue 2 - pp 218-230

February 2009 - Volume 110 - Issue 2 - pp 218-230

Continuous Thoracic Paravertebral Block

paravertebral block

Thoracic Paravertebral Block
Joe Loader, Pete Ford*

The thoracic paravertebral
block was first described
in the treatment of chronic
pain. More recently, the
technique has also been
used to provide surgical
analgesia for a variety of
applications, including
thoracic, breast, and general
surgery. It is possible to
provide analgesia lasting into
the postoperative period,
and certain procedures may
be performed without the
need for general anaesthesia.
spinal column. The space is defined medially
by the vertebral body and the intervertebral disc and
foramina, antero-laterally by the pleura and posteriorly
by the superior costotransverse ligament, running
between adjacent transverse processes. Above and below,
the space communicates freely with adjacent levels. The
paravertebral space is also in communication with the
vertebral foramina. The ventral and dorsal primary rami
traverse the space, carrying sensory afferents and form
the spinal nerves. In addition, the space contains the
sympathetic trunk which communicates with the spinal
nerves via the gray and white rami communicantes.
Thus local anaesthetics introduced into this space may
produce sensory, motor and sympathetic blockade over
several dermatomes.

TECHNIQUE FOR PVB
Obtain consent before starting. It is essential to ensure that full
resuscitation facilities are available and that monitoring including
ECG, pulse oximetry and blood pressure measurement is in place.
Intravenous access should be secured.
Equipment
Skin preparation (e.g. chlorhexadine 2%), skin marker, Tuohy needle
(22G), extension tubing, 20ml Leur-lock syringe, 0.5% bupivacaine
PVB may be performed awake, in which case the sitting position may
be preferable, or with the patient anaesthetised in the lateral position.
The site of surgery determines the level of PVB as shown in Table 1.
Table 1. Dermatomal sites for different surgical procedures
Surgery Dermatomes Level of PVB
Thoracotomy T3 – T9 T3 – T9
Breast surgery T1 – T6 T1 – T5
Cholecystectomy T4 – L1 T6 – T12
Inguinal herniorrhaphy T10 – L2 T10 – L2
Use the scapula and the processus prominens as landmarks. The
processus prominens is the most prominent upper thoracic vertebral
prominence and is the spinous process of T1. The most inferior
palpable part of the scapula lies at the level of T7.
Locate the spinous processes corresponding to the required levels
of block and make a mark 2.5cm lateral to each of them (Figure 3).
Under aseptic conditions, a skin wheal of local anaesthetic is placed
at each mark. If sedation is used, then supplemental oxygen should
be administered.
A B

If bone is not contacted, the needle should be withdrawn and redirected
superiorly, and if still not successful, inferiorly.
When the needle contacts bone, the depth is noted, the
needle is then withdrawn and re-directed inferiorly to ‘walk-off’ 1cm
past the inferior edge of the transverse process. A ‘click’
can sometimes be felt as the needle passes through the superior
costotransverse ligament. It is imperative to locate the transverse
process before advancing the needle any further to prevent inadvertent
pleural puncture.
To increase the duration of the block it is possible to insert a catheter
and run a continuous infusion or administer intermittent boluses of
local anaesthetic.
ADVANTAGES OF PVB
• Simple and quick to learn
• Avoids the potential complications of a thoracic epidural
• Reduced postoperative pain
• Lower postoperative analgesic requirements
• Reduced postoperative nausea
• Reduced incidence of chronic pain after breast surgery.
CONTRAINDICATIONS
Absolute
• Cellulitis or cutaneous infection at site of needle puncture
• Empyema
• Tumour occupying the paravertebral space
• Allergy to local anaesthetic drugs.
Relative
• Coagulopathy
• Kyphoscoliosis - deformity may predispose to pleural puncture
• Previous thoracotomy - scarring may cause adhesions to the parietal
pleura and increase the risk of pneumothorax.
COMPLICATIONS
• Sympathetic blockade and hypotension
• Horner’s syndrome is frequent, short duration and of no lasting
consequence, but patients should be warned. Incidence is between
5 and 20%
• Vascular puncture
• Haematoma
• Pneumothorax. The incidence is between 0.01 to 0.5%. Risk of
bilateral pneumothorax should be considered if performing bilateral
blocks. If pleural puncture occurs, a chest radiograph should be
obtained to exclude pneumothorax A chest radiograph is not
routinely required otherwise.
• There is one single report of a haemothorax, using a loss of resistance
technique

Continuous Femoral Nerve Block

Single Injection Femoral Nerve Block

FEMORAL NERVE BLOCK

 
 FEMORAL NERVE BLOCK

Historically this block was also known as the “3-in-1

block,” suggesting that the femoral, lateral femoral

cutaneous, and obturator nerves could be blocked

from a single paravascular injection at the femoral

crease. Studies have since demonstrated that the

femoral and lateral femoral cutaneous nerves

can be reliably blocked by a single injection, but

the obturator nerve is often missed. Therefore, a

posterior lumbar plexus block should be used when

all three nerves need to be anesthetized (although

this point remains controversial). The femoral

nerve block is an ideal block for surgeries of the

hip, knee, or anterior thigh and is often combined

with a sciatic nerve block for near complete lower

analgesia. Complete analgesia of the leg

can be achieved without lumbar plexus block by

extremity

combining a femoral nerve block with parasacral

sciatic nerve block (which blocks the obturator

over 90% of the time), or by adding an individual

obturator nerve block to the femoral nerve block.

ANATOMY

The femoral nerve, formed by the dorsal

divisions of the anterior rami of L2–L4, is the largest

terminal branch of the lumbar plexus. It travels

through the psoas muscle, leaving the psoas at its

lateral border. The nerve then descends caudally

into the thigh via the groove formed by the psoas

and iliacus muscles, entering the thigh beneath the

inguinal ligament . After emerging

from the ligament, the femoral nerve divides into

an anterior and posterior branch. At this level it is

located lateral and posterior to the femoral artery

. The anterior branch provides motor

innervation to the sartorius and pectineus muscles

and sensory innervation to the skin of the anterior

and medial thigh. The posterior branch provides

motor innervation to the quadriceps muscle (rectus

femoris, vastus intermedius, vastus lateralis, and

vastus medialis) and sensory innervation to the

medial aspect of the lower leg via the saphenous

nerve.

The anatomic location of the femoral nerve makes

this block one of the easiest to master because the

landmarks are usually simply identified (except in

cases of morbid obesity), the patient remains supine,

and the depth of the nerve is relatively superficial.

PROCEDURE

Landmarks.

anterior superior iliac spine and the pubic symphy

and draw a line between these two landmarks.

This line represents the inguinal ligament. The

Place the patient supine, identify thesis,

femoral nerve passes through the center of the line,

which makes this landmark useful for positioning

the needle in the inguinal crease, particularly in an

obese patient. Then palpate the femoral pulse and

mark it at the inguinal crease. Studies have dem

that the most successful point of needle

onstrated

entry is directly lateral (1–1.5 cm) to the artery in the

inguinal crease. At this location the femoral nerve is

wide and superficial, and the needle does not pass

through significant muscle mass. Direct the needle

cephalad toward the center of the inguinal ligament

line.

Needles

• 22-gauge, 5-cm insulated needle.

• 18-gauge, 5-cm insulated Tuohy needle for

catheter placement. The catheter is inserted 3 to 5

cm for the femoral block.

Stimulation.

The nerve stimulator is initially set

at 1.0 to 1.2 mA. The needle is directed cephalad at

approximately a 30° to 45° angle. A brisk “patellar

snap” with the current at 0.5 mA or less is indica

of successful localization of the needle near

tive

the femoral nerve. The nerve is usually superficial,

rarely beyond 3 cm from the skin .

Local Anesthetic.

In most adults, 20 to 40 mL of

local anesthetic will produce a successful femoral

block.

Teaching Points.

Studies have demonstrated

that the anterior branch of the femoral nerve is

usually encountered with the first needle pass,

which results in stimulation of the sartorius

muscle, often seen as contraction of the lower

medial thigh. If this occurs, advance the needle

tip until either the sartorius twitch is extin

or a patellar snap is elicited before redi

the needle. If the sartorious twitch is ex

without the patellar snap, withdraw

guishedrectingtinguished

the needle toward the skin (without exiting

the skin), and redirect it slightly lateral and

slightly deeper than the original needle pass.

The posterior branch of the femoral nerve is

typically lateral and deep to the anterior branch.

The anesthetist should resist the urge to use

the patient’s thigh as a hand rest while directing

the needle. Stimulation of the femoral nerve can

result in brisk vastus muscle twitching that can

disrupt needle positioning.

The femoral nerve block provides analgesia to

the anterior thigh, including the flexor muscles

of the hip and extensor muscles of the knee.

cervical plexus block

INTRODUCTION

The cervical plexus block provides anesthesia

and analgesia to the head and neck region.

Depending on the type of surgery, the plexus can

be blocked either at a superficial or a deep level.

The superficial branches (Figure 6-1) of the plexus

innervate the skin and superficial structures of

(Figure 6-2) innervate the muscles of the deep

anterior neck and the diaphragm. The deep cervical

plexus block is used for deeper surgeries of the

neck, such as carotid artery or thyroid surgery, and

-

ANATOMY

The cervical plexus is formed from the anterior

rami of the C1 through C4 nerve roots; it lies

the sternocleidomastoid muscle. There are five main

components of the cervical plexus: (1) the cutaneous

branches, which supply the lesser occipital, greater

auricular, transverse cervical, and supraclavicular

nerves; (2) the ansa cervicalis, which innervates the

infrahyoid and geniohyoid muscles; (3) the phrenic

nerve, which is the only motor nerve to innervate

the diaphragm; (4) contributions to the accessory

nerve (CN XI), which innervates the sternocleidomastoid

and trapezius muscles; and (5) direct

muscular branches, which supply prevertebral

muscles of the neck.

would result in total diaphragmatic paresis, should

not be performed. Also, patients with chronic respiratory

conditions may not be suitable candidates for

an ipsilateral deep cervical plexus block. Caution

must be taken when placing a deep cervical plexus

block because of the close proximity of the vertebral

close to the vertebral artery may result in an intravascular

injection; placing it too close to the dural

sleeve may result in a subarachnoid injection.

perficial cutaneous surgeries of the head and neck.

This block is also useful as a supplement to other

24

6

PROCEDURE

Landmarks

Superficial Cervical Plexus

 Identify and mark the posterior border of the sternocleidomastoid,

as well as the midpoint of the muscle.

Deep Cervical Plexus

Position the patient supine with the head turned toward the

nonoperative side. Palpate the transverse process

of C6 (Chassaignac’s tubercle) at the level of the

cricoid cartilage. Palpate the mastoid process

behind the ear. Draw a line between the mastoid

process and Chassaignac’s tubercle. The transverse

processes of the other cervical vertebrae

will lie on or near this line. The first palpable

transverse process below the mastoid process is

C2. Palpate and mark the transverse processes of

C2 to C4 (the C4 transverse process lies approximately

at the level of the mandible). Insert the needle medially and caudally so that the needle tip is resting on the transverse process.

• 22-gauge, 5-cm, short bevel needle.

Injection

Superficial Cervical Plexus

Insert the needle at the midpoint of the posterior border of the sternocleidomastoid muscle to approximately half the depth of the muscle, and inject 3 to 4 mL of local anesthetic.

Also perform a subcutaneous injection of additional

local anesthetic cephalad and caudad along the

length of the sternocleidomastoid muscle posterior

border.

Deep Cervical Plexus

. Attach a 10-mL control syringe to the needle. Once the transverse process is contacted, withdraw the needle 1

to 2 mm. Inject the local anesthetic slowly with frequent aspirations.

After completing the injection, remove the needle

and repeat the block at the next level. (Many institutions

perform only a superficial cervical plexus block, and the

surgeon infiltrates deeper structures as required.)

Local Anesthetic

Superficial Cervical Plexus

 5–10 mL.

Deep Cervical Plexus

 3–5 mL at  each level or 15 mL at C3 only.

Needles

regional techniques of the upper torso.

artery and the dural sleeve. Placing the block too

Bilateral deep cervical plexus blocks, which

anterior to the cervical vertebrae and posterior to

the superficial cervical plexus block is used for su

the head, neck, and shoulder. The deep branches