Neuraxial Anesthesia Flashcards
History of the spinal
___64 - Cerebral spinal fluid was first
identified by Cotugno
18__ - Corning was the first documented
individual to inject into the intraspinous space
18__ - Quincke used spinal needles to
relieve elevated ICP in patients with
tubercular meningitis
1764
1885
1891
Cervical and thoracic spinals are less popular because:
accidentally injecting into the spinal cord, a syrinx can form that will grow and grow until it leads to death
Entire gut arises embryologically from what dermatome and indicates the entire abdomen is anesthetized?
T10
Where do you block during labor? There are 2 stages and two dermatome ranges.
1st stage: T8-T10 for uterus contraction
2nd stage: T10-L1, L3 during delivery
What dermatome innervates kidneys and uterus?
T10
What dermatomes innervate the vaginal introitis?
S2-S3
What dermatome innervates the anus?
S4
Sensory pathways can ascend as much as two levels higher. In other words, Uterine pain can be felt as high as T8. True or false?
True
Things that you can alter in an epidural: (5)
location of needle–center of LA action
infusion rate
drug
concentration
other adjuncts
A L5/S1 epidural requires a rate of ____
cc/hr to achieve a T10 block
14+
A T10 epidural requires a rate of ___ cc/hr to
provide adequate labor analgesia
4
The rate of infusion is equal to the _____ of your anesthetic.
Rate = Distribution
Rate = Distribution
Rate = Distribution
What are the signs of systemic toxicity? (3)
ringing in ears
funny taste in the mouth
numbness around the mouth
What LA has a fast onset?
chloroprocaine
What LA has intermediate onset?
lidocaine
What LA has a slow onset?
bupivicaine (4-6 minutes)
Nerves affected in what order?
Sympathetics first
sensory
motor
What is a downside to using chloroprocaine? (2)
tachyphlaxis
interferes with opioid effectiveness
Not recommended for surgergy > 1 hour
Procaine onset?
Duration?
3 minutes
30-40 minutes
Lidocaine onset?
Duration?
Problems?
4-5 minutes
45-60 minutes
tachyphlaxis
The lower the pKA, how is the onset affected?
faster onset
_____ affects what you feel and wheter you retain motor function.
Concentration
Thus adjust concentration not rate when making adjustments!
How does epinepherine increase effectiveness of local? (2)
decreased uptake
increased duration
What are several adjucts to LA to lower concentration of anesthetic administered? (3)
epi
clonidine
opioid like Duramor, is a preservative-free one
How do we prepare for an epidural? (3)
get consent
give lots of fluids to prevent hypotension, prefer coload
get position
Goal of epidural for labor and delivery rate:
T8 - L3, min 14+ cc/hr
What approach do we prefer for elderly pts?
paramedian because of calcified supraspinous ligament
What position is better during an emergency?
lateral decubitus because pt can’t fall and fetus will not be distressed if pregnant patient
What position is technically more difficult?
lateral decubitus
Where do we want to place a spinal needle?
around L2
Preload is the act of administering a bolus
of ___-___ L immediately prior to placing a
neuraxial block.
Coload is the administration of ___-___ L fluid
as a block is in the process of setting up
1-2
Air vs. Normal Saline
Downside of ___ : it can track around nerve
roots and prevent exposure to local
anesthetics
air
What is the test dose of lidocaine and epinepherine?
45 mg at 1.5% lidocaine
and 15mcg of epi at 1/200,000
How much should we thread the catheter?
3-5 cm is ideal
What do you look for in the test dose to indicate that you are in the right epidural space?
tachycardia
HTN
perioral numbness
hearing changes
metallic taste
profound numbness
What are some troubleshooting issues? (4)
inadequate analgesia: no block, one-sided, patchy, or wears off too quickly
puritis
hypotension
too dense
What should you document when removing epidural catheter?
blue tip intact
What if you determine there is no block? What do you do?
start over
If patient complains that they are only feeling it on one side. What may have happened? (2) What do you do?
Catheter may be in too far, or pt was lying on the side for too long
Septated epidural space
Replace it
What may have occurred in a patchy block? What is it called?
a window
It can be caused by air around the nerve root.
It is also possible that a certain nerve may be repeatedly stimulated.
How do you treat a patchy block? (4)
volume bolus
withdraw the catheter 1-2 cm
lie the patient “window” side down
small bolus of higher concentration LA vs. opioid bolus
The patient appears to have a complete motor
block of the left leg but not the right. There is a
sensory block T10 bilaterally. The left side has no
sensory block above T10. Horner’s Syndrome has
appeared on the right.
Remove and start over
numb skull!
Give ventilatory support!
Block that “wears off”
What is the solution? (2)
- You forgot to start the infusion
- The infusion isn’t connected/set up properly
The patient’s block is actually working but
they aren’t as numb… which is appropriate
The patient is ready to push
The patient has developed a comorbidity
(chorio vs. uterine rupture vs. something else)
How do you treat hypotension?
Left or right uterine displacement
fluid bolus 500cc-1L
ephedrine 10 mg
phenylephederine is better! Less fetal acidosis
check for bradycardia/dysrhythmias
check for alternative causes: Mg, hemmorhage, vagal
Can a paraplegic deliver a baby vaginally?
yes!
If the patient is “too numb” or “can’t push”.
You are called because the patient can’t feel her legs and the OBs are concerned that she won’t be able to push.
DECREASE CONCENTRATION in the epidural
Inject 5-10 cc NS through catheter
The ___ receptor is THE cause of pruritis?
What is the treatment?
mu
mu antagonist!
