Chapter 5 - Reional Analgesia Techniques Flashcards
Continuous infusions of AMIDES should be reduced by ____ % in infants < 6 months.
30%
- The hepatic pathways for conjugation of the amide locals are immature.
- Neonate has less capacity to metabolize Bupivicaine
- Clearance at 1 month of age is only 1/3 of adult rates
- By 9 months, clearance reaches adult rates
T/F
The greater the volume of distribution of a local anesthetic also prolongs the elimination 1/2 life.
T
- Plasma levels of Bupivicaine after administration of a 2.5 mg/kg dose in the epidural space in infants are significantly LESS than in younger children
What sites on albumin does bilirubin bind to?
Acidic sites on albumin protein
What sites on albumin does Bupivicain bind to?
Basic sites on albumin protein
By how many months of age has the clearance of bupivicaine (Amide) reached adult rates?
9 months of age
- The hepatic pathways for conjugation of the amide locals are immature.
- Neonate has less capacity to metabolize Bupivicaine
- Clearance at 1 month of age is only 1/3 of adult rates
- By 9 months, clearancereaches adult rates
Bupivicaine infusion should be limited to how long and what rate?
Limited to 48 hrs
&
0.2 mg/kg/hr
T/F
Levobupivicaine is less cardiotoxic than bupivicaine and 20% less potent
F
- 20% MORE potent
- Suitable for prolonged infusion
What agent has gained popularity as an agent for caudal analgesia?
Ropivicaine
When compared to Bupivicaine:
- Same sensory block and duration
- More rapid onset
- Less cardiotoxic
- Less motor block
T/F
Ropivicaine should not be used for penile or digit nerve blocks.
Why or Why not?
T
Vasoconstriction and ischemia have been reported
What is the treatment plan for seizures due to local toxicity?
- 100% O2
- Intubate
- Benzodiazepine (Midazolam [Versed] 0.05 - 0.2 mg/kg)
** or**
Thiopental 2 - 3 mg/kg
** or**
Propofoal 1 -2 mg/kg
Acute intravascular (IV or IO) injection of Bupivicaine may cause V-tach and difficulty restoring NSR which can result in low CO. What therapy can be implemented to elude the local anesthetic from the myocardium?
IV Intralipid 20% at 1ml/kg loading dose
followed by
1 ml/kg Q 3 to 5 min.
or
infusion of 0.25 to 0.5 ml/kg/min
A maximum total dose of 8 - 12 mL/kg is recommended
T/F
Propofol can also be used to substitute for Intralipid 20% therapy after local toxcity with acute mycardial dysfunction, but at lower doses (0.5 to 0.75 mg/kg)
F
Propofol should NEVER be substituted for Intralipid
Why may lidocaine in normal doses in children with right-to-left cardiac shunting cause toxic effects?
The normal first-pass absorption within the pulmonary circulation is bypassed
- Dose should be reduced by AT LEAST 50%
What are more reliable signs of intravascular injection of a local anesthetic with epinephrine than tachycardia?
Peaked T waves
and
ST elevation
- May be more difficult to assess and therefore is a less sensitive warning sign in children
- Epinephrine may interact with halothane and precipitate arrhythmias
- Doses of epinephrine up to 10 mcg/kg by infiltration are considered safe in children
Clonidine, at what dose, can be added to local anesthetics for use in the caudal/epidural space?
Clonidine 1 - 2 mcg/ml
- This will prolong effect for ~3 hrs
- However, has INCONSISTENT effects on the rate of elimination of the local from epidural space
- In preterm infants, apnea reported after epidural administration
- Also may contribute to postop sedation (doses >2 mcg/kg) so, undesirable in outpatients
Spinal cord may extend to as low as what level in the infant?
L3
- compared to L1 - 2 in the older child or adult
- Perform lumbar puncture at L4 - 5
The dural space extends to what level in the neonate?
S3 - 4
T/F
The volume of CSF in infants is relatively smaller than in adults
F
- Infants = 4 ml/kg
- Adults = 2 ml/kg
What are the contraindications for spinal or epidural?
- Sepsis
- Infected lumbar puncture site
- Coagulopathy
- No consent
When performing a spinal, what is the size & how do you prepare a neonatal spinal needle and syringe?
22 g or 25 g
1 in.
Measure dead space with tb syringe
- Prepare a syringe containing 0.4 to 1.0 mg/kg of 1% tetracaine mixed with equal volume of 10% dextrose
PLUS
- a volume of this mixture equal to the dead space of the needle (aprox 0.2 ml)
For thoracc/abdominal surgery in preterm infants (
1 mg/kg
1 % Tetracaine
or
0.5% or 0.75% Bupivicaine
When inserting the needle for a spinal, how should the needle face and at level should you be?
L4 -5
and
bevel facing laterally
- Inject slowly to prevent a high or total spinal
After a spinal has been provided for the infant and returned to supine position, where should the BP cuff nd pulse ox be placed?
On the lower extremity
After a spinal is provided, how long is the duration of anesthesia?
1.5 hours
What block has also been used as an alternative to spinal analgesia for lower abdominal surgery in infants?
Caudal block
Continuous caudal catheters have been used intraop for more prolonged surgery, and they may safely be threaded to….?
T6
- Infection has not been a problem when catheters have been left insitu for 3 days
Caudal morphine provides analgesia for thoracic and abdominal procedures and reduces the need for systemic analgesic drugs, however, caudal opiods are associated with what side effects?
- N/V
- RARE respiratory depression
_**Unsuitalble for outpatients and for infants_
How should the child be positioned and what are the landmarks for a caudal block?
- Placed in lateral position with upper knee and hip well flexed
- Landmarks are:
- Tip of coccyx to fix the midline and the sacral cornua bounding the sacral hiatus (Apex of triangle)
- Posterior superior iliac spines Draw a line between them - (Base of triangle)
Besides the addition of clonidine to bupivicaine to extend the duration of action for caudal anesthesia, what other 2 meds have been reported to extend the duration of action?
Preservative free Midazolam
and
Preservative free Ketamine
For caudal administration, what is the volumes to be injected via this route for Perineal surgery? What about lower abdominal surgery?
Perineal surgery = 0.5 ml/kg
Lower abdominal surgery = 1 ml/kg
Caudal morphine in a dose of _____mcg/kg, diluted in preservative free saline to a volume of 0.5 ml/kg and administered as a single shot preoperatively, provides analgesia for up to _____hours.
caudal Morphine at dose of 30 mcg/kg = Analgesia for 12 hours
- Maximun analgesia and duration is achieved with this dose
- Greater doses increase compplication rate
For continuous caudal analgesia in neonates, infants, and children up to 5 years of age, what size epidural catheter may be threaded through an 18g IV cannula and advanced to desired level?
20g epidural catheter through 18 g IV cannula
During continuous caudal analgesia, a continuous infusion of bupivicaine may be given at ____ ml/kg/hr in a concentration that is calculated to deliver a safe dose.
0.3 ml/kg/hr
T/F
When performing a lumbar epidural block, the loss of resistance method with air or saline can be used
F
- Air should NOT be used to test for LOR because an intravascular injection may occur
What is the aproximate distance from skin to lumbar epidural space in mm for a 17 kg child?
17 mm
- A child weighing >10 kg, distance from skin to lumbar is aproximately numerically similar to the child’s weight in kg
- 11 kg = ~ 11mm
- 12 kg = ~ 12 mm
- 13 kg = ~ 13 mm
- …..and so forth
What size touhy needle and epidural cath usually used for children ?
What about >5 years of age?
>5 years of age = 18g (5 cm) touhy & 20g catheter
T/F
For continuous infusion of epidural analgesia, the maximum rate of bupivicaine administration should not exceed 0.4 mg/kg/hr in children and 0.2 mg/kg/hr on neonates.
T
T/F
Urinary retention, pruritus, and vomiting may be more common after epidural opioids in adults than in children
F
More common in children than in adults
Intercostal nerve block at what level may be performed to relieve pain after umbilical hernia repair?
Bilateral at T10
The intercostal space is very vascular and absorption can be extremely rapid. For this reason, take care not to exceed a ttal dose of ___ mg/kg of bupivicaine?
How can you limit the absorption?
Do not exceed a total dose of 2mg/kg bupivicaine
To limit absorption, epi MUST be added to bupivicaine when applied for intercostal blocks
The order of local anesthetic absorption with different blocks is easily remembered by which acronym?
“ICE Blocks”
Speed of absorption: Intercostal, Caudal, Epidural Blocks
Performance of an intercostal block, comes with a high risk of _______, especially in small children where the distance from nerve to pleura is very small?
Pneumothorax
The intercostal nerves are sheathed in a dural layer posteriorly; injection near their origin can result in…?
a total spinal block
In performing a intercostal block in infants and small children, the nerve in the intercostal space can be more precisely approached by angling the needle __________?
Angle needle posteromedially
so that it lies almost parallel to the rib rather than at right angles
- Palpate the lower margin of the rib
- Pull skin upward and advance until contacting the rib
- The skin is released and the needle “walked” off the rib margin
- The chosen volume is injected with only a 1 to 3 mm advancement and frequent aspiration for blood
Which block is useful for providing postop analgesia after herniotomy?
Ilioinguinal and iliohypogastric nerve block
- A fan shaped infiltration of the abdominal wall in this region blocks these nerves
What is the location of the ilioinguinal and iliohypogastric nerve?
Beneath the internal oblique muscle
and
Medial to the anterior superior iliac spine
T/F
The ilioinguinal and iliohypogastric nerve block is adequate for herniotomy and orchidopexy
F
This block is INADEQUATE for orchidopexy; a caudal block is preferred
T/F
The penile block provides good pain relief after a circumcision as well as a hypospadius repair since it blocks the paired dorsal nerves that supply the dorsal aspect of the penis and foreskin
F
The penile block is INADEQUATE after hypospadius repair
The dose of 0.2 mg/kg of 0.5% bupivicaine without epi is injected,to a volume of ___ml for a small infant?
What amount for larger child in ml?
Small infant = 1 ml
Larger child = 6 ml
What is the preferred techinique for a penile block?
Bilateral injections made beneath the pubis at the base of the penis at the 11 o’clock and 1 o’clock positions
- Needle felt through Buck’s fascia
- Possible in in infants to anesthetize both nerves with one midline injection
- Alternatively, a ring block at the base of the penis may be performed
What block provides good analgesia for infants and children after cleft lips repairs or undergoing endoscopic sinus procedures?
Infraorbital Nerve block
In older children, the site of the infraorbital foramen can be palpated where?
1 to 1.5 cm below the infraorbital rim in line with the supraorbital notch and the pupil
- A needle can be inserted at this point
- 1 to 1.5 ml of local injected
In infants the foramen cannot be palpated and the infraorbital nerve position must be estimated by using what landmarks?
The infraorbital nerve lies aprox under the midpoint of a line drawn between:
the middle of the palpebral fissure
and
the angle of the mouth
Which block provides analgesia for a posterior venticular peritoneal shunt?
Greater Occipital nerve block
The preferred technique for an infraorbital nerve block is to estimate the position of the infraorbital foramen and pass a needle vertically through skin until bony resistance is felt. then withdraw needle and aspirate. Injection of ___ ml of 0.25% bupivicaine with epi or 0.2% ropivicaine.
1 ml
Infraorbital nerve block can also be done by avoiding a skin puncture. How?
- Lift the upper lip
- Pass a 27g needle via buccal sulcus
- Palpate the infraorbital foramen (to avoid entering the orbit)
Where is the greater occipital nerve located?
The greater occipital nerve exits the skull next to the medial accipital artery at the level of the superior nuchal line
How many ml of local is administered for the greater occipital nerve block?
1 to 3 ml of 0.25% bupivicaine with epi or 0.2% ropivicaine
T/F
The greater occipital nerve block is usedful in the child who has an incision behnd the ear for mastoid surgery or tympanoplasty
F
The superficial cervical plexus block
The nerves of the superficial cervical plexus may be readily blocked at what location?
What are the two nerves blocked?
Location: The posterior aspect of the sternocleidomastoid muscle
Nerves: Greater auricular nerve and Posterior occipital nerve
What are the three most common approaches to the brachial plexus block?
Axillary
Supraclavicular
Infraclavicular
Out of the three most common approaches to the bracial plexus block, which one lacks the risk of pneumothorax?
Axillary approach
Out of the three most common approaches to the brachial plexus block, which one provides more reliable analgesia in the musculocutaneous nerve distribution?
Lateral infraclavicular approach
T/F
When performing an axillary appraoch to the brachial plexus block, the needle is advanced cephelad at a 45 degree angle to the skin alongside and perpendicular to the axillary artery.
Parallel to the axillary artery
When using a nerve stimulator for the axillary approach brachial plexus block, a motor respons should be detected in which nerves with0.2 mA stimulation?
Ulnar
Radial
Median
When injecting the local in an axillary approach to the brachial plexus, pressure should be placed distally over the axillary artery in order to encourage what?
Proximal spread of the local and a more complete block
For the older child receiving an axillary approach to a brachial plexus block, a maximum volume of ___ml is usually satisfactory.
20 ml of any local
T/F
The infraclacicular approach to the brachial plexus block has a higher risk of pneumothorax than the axillary approach
T
T/F
When using a nerve stimulator for the infraclavicular approach to brachial plexus block, wrist or forearm extensor movements when stimulated with 0.5 mA are predictive of success
T
Axillary approach to brachial block does not include the area of the upper arm. so, which appraoch can be performed for surgery of the upper arm?
Supraclavicular approach
- Risk of pneumothorax
- Risk of vertebral artery injection
- With nerve stimulator, any movement of upper arm is accepted (1 mA)
- Volumes are 0.15 to 0.2 ml/kg
Which block is useful for fractures of the shaft of the femur and muscle biopsy in patients with suspected myopathies?
Femoral nerve block
Combined with a lateral femoral cutaneous nerve block
For a continuous femoral nerve block, intermittent top-up doses of bupivicaine 0.25% (0.4 ml/kg) may be given every __ to ___ hours as required
or
a continuous infusion may be used at what rate?
top-up doses every 8 to 12 hours
or
continuous infusion of 0.1 ml/kg/hr
Where is the needle inserted for a lateral femoral nerve block?
Inserted medial and inferior to the anterior superior iliac spine
Superior to the inguinal ligament
Advanced superiorly and laterally until it impinges on the iliac bone
Volume of local to be injected for a lateral femoral cutaneous nerve block?
2 to 5 ml
of
1% lidocaine with epi
or
0.5% bupivicaine
injected in a fan like manner
What three approaches are there to provide a sciatic nerve block?
Which approach is considered the easiest?
Anterior
Lateral
Posterior (easiest)
What is the preferred position of the patient receiving a sciatic nerve block?
semiprone position
with side of nerve to be blocked elevated
In a sciatic nerve block, the needle should be inserted at right angles to the skin where?
At the midpoint of a line between:
the sacralcoccygeal membrane
and
the greater trochanter of the femur
- Confirm by US or by electrical stimulation (0.5 mA)
- A sheathed insulated needle should be used
Volume to be injected for sciatic nerve block for a single dose?
For continuous infusion?
Single dose: 0.2 to 0.3 ml/kg
Continuous infusion: 0.1 ml/kg/hr
Which block is useful to provide analgesia for foot surgery?
Popliteal fossa block
of the sciatic nerve
The sciatic nerve, just proximal to the popliteal fossa, the nerve spilts into what nerves?
Tibial nerve
and
Peroneal nerve
The tibial nerve innervates…?
Posterior calf and plantar area
The peroneal nerve innervates…?
Supplies sensation to anterior leg
In order for the popliteal fossa block to be successful, the block MUST be performed where?
Above the division site
- 3 to 7 cm above the popliteal crease in children under 8 years
- Slightly higher in older children
- Approximate site to make injection is 1 cm proximal to the popliteal crease for each 10 kg
A single dose of how many mL is reccomended for a popliteal fossa block?
cWhat aboout the dose for a continuous infusion?
Single dose: 5 to 10 mL
Continuous infusion: 0.1 ml/kg/hr
Which block may provide good analgesia for club foot surgery?
Ankle block
What are the nerves blocked with an ankle block and their locations?
- Deep peroneal
- Alongside anterior tibial artery
- Superficial peroneal nerve
- Aspect of anterior tibia
- Saphenous nerve
- Alongside saphenous vein
- Posterior tibial nerve
- Alongside posterior tibial artery
- Sural nerve
- Lateral to Achilles tendon
When performing a bier block, do not exceed what dose of 0.25% lidocaine?
Do not exceed what dose of prilocaine?
What about dose for bupivicaine?
With Bier block, do not exceed:
5 mg/kg 1% lidocaine
3 mg/kg prilocaine
Bupivicaine should never be used for IV block!
After the bier block has established (5 min), inflate the distal cuff and then deflate the proximal cuff. Do not release the remining cuff until at least how many minutes have elapsed?
Wait 30 minutes
Even if the surgery is complete!
What is the maximum dose of Bupivicaine Plain or with epi?
Bupivicaine 2.5 mg/kg
What is the maximum dose of Ropivicaine?
3.0 mg/kg
What is the maximum dose of lidocaine without epi?
4.5 mg/kg
What is the maximum dose of Lidocaine with epinephrine?
7 mg/kg
