Exam 1- Neuraxial Principles (6/5/23) Flashcards
What mechanism causes hypothermia/shivering?
The redistribution of blood flow and heat to the periphery due to vasodilation. usually with hyper/hypobaric solutions
What equipment should always be in the operating room (except for pediatric cases)?
Bair hugger
Will a Bair hugger work for neuraxial anesthesia?
Not really
What drug can prevent/treat neuraxial shivering?
Ondansetron (Zofran) 4-8 mg
Which 2 monitoring equipment do you absolutely need during neuraxial anesthesia administration?
BP cuff and pulse ox
If you gave a lot of versed in pre-op, what else might the patient need?
Oxygen
If you need to convert to general anesthesia, what materials do you need?
- Favorite blade
- ETT (2 sizes) with stylet and 10cc syringe attached
- Drugs (Fentanyl, Lidocaine, Propofol)
- Optional: tongue depressor, oral airway
What is a failed block?
For some reason, the anesthetic doesn’t set in or is not reaching the desired level of block. Will need to convert to General.
What are other reasons to convert to GA?
- High Spinal
- LAST
- Anaphylaxis
- Severe CV collapse
- Case exceeds duration of local anesthetic
What is the treatment for Local Anesthetic Systematic Toxicity?
Intralipids 20% 1.5 mL/kg Bolus followed by 0.25 mL/kg drip
While waiting for intralipids 20% to arrive from the pharmacy, what drug can you give instead that may buy you some time?
Propofol (1%)
Among anesthesia meds, what type of drug has common allergy-related issues?
Muscle relaxants (Rocuronium)
Allergy to LAs are rare, but if one does occur, the LA was probably an _____.
Ester
What is the ester derivative?
PABA (Para-Aminobenzoic Acid)
How can you tell if the LA is wearing off during the case?
The patient will say it hurts
A patient assessment for neuraxial anesthesia is the same as general, but what is especially important to ask about?
Anticoagulants and Antiplatelets
- What are they taking, when did they stop or are they still taking them, etc?
When obtaining informed consent, what are the risks of spinal anesthesia that the patient needs to be aware of?
- Hypotension
- Headache
- Hematoma
Dermatome level: C-section/upper abdominal surgeries
T4
Dermatome level: urologic/gynecologic/lower abdominal surgeries
T6
Dermatome level: Testicular procedures
T8
Dermatome level: Vaginal delivery/uterine/hip procedure/tourniquet/TURP
T10
Dermatome level: Thigh/lower leg/knee surgery
L1
Dermatome level: Foot/Ankle surgery
L2
Dermatome level: Penis
S2
Dermatome level: Scrotum
S3
Dermatome level: Peri-anal/anal surgery (“saddle block”)
S2-S5
Spinal Block Set-Up Tray
Which type of spinal needle increases the incidence of post-dural puncture headache?
Cutting
Which type of spinal needle will have a more noticeable “pop”?
Non-cutting/Pencil-point
Besides decreased incidence of PDPH and noticeable “pop”, what is another advantage of non-cutting/pencil-point needles?
They “drag” fewer contaminants into subnormal tissue.
What is the risk of PDPH using a non-cutting needle?
< 1%
Know the steps of a Spinal procedure.
When confirming placement during a spinal, how do you differentiate between CSF and the LA used to numb the insertion site?
CSF will be warm
What is one method to improve the flow of CSF after inserting the spinal needle?
Rotate the needle 360 degrees.
If the LA isn’t hyperbaric, how will you know you’re aspirating CSF without the “swirl”
The volume of the syringe will still increase.
When removing the spinal needle and introducer, what is done to prevent shearing?
Pull them out together.
What needs to be put on the patient after laying them down?
EKG leads
What are the two possible positions for spinal anesthesia?
- Sitting (most common)
- Lateral
What is the best type of case to practice spinals in the lateral position?
Hip surgery (the sitting position hurts these pts)
Describe the lateral position.
- Parallel to the edge of the bed
- Legs flexed to the abdomen
- Forehead flexed down toward knees
What are the two approaches to neuraxial anesthesia?
- Median (most common)
- Paramedian
What cases might require a paramedian approach?
- Spinal deformities (i.e. scoliosis, rods)
What layers are transversed during a median approach?
- Skin
- Subcutaneous fat
- Supraspinous ligament
- Interspinous ligament
- Ligamentum flavum
- Dura Mater
- Subdural space
- Arachnoid Mater
- Subarachnoid space
How much of a degree shift is a paramedian spinal block approach?
- 10 to 15 degrees
What layers are transversed during a paramedian approach?
- Skin
- Subcutaneous fat
- Ligamentum flavum
- Dura Mater
- Subdural space
- Arachnoid Mater
- Subarachnoid space
The spinal needle is already deeply inserted, and it feels as if it is in the right place, but there is no CSF. What would you do?
- Rotate the needle 90 degrees and wait for 10 to 15 seconds; repeat if necessary
- Insert the stylet and remove it.
- Try to aspirate at different rotating angles.
- If no CSF can be aspirated, you have directed the needle too laterally.
- Withdraw the needle, check the position of the patient, and try again
There is blood in the needle during a spinal block procedure. What would you do?
- There may be some blood from the epidural space; usually, it clears when a few drops of CSF are allowed to drip.
- However, if the blood continues to drip, the position of the needle must be changed
- Most probably, it is in an epidural vein.
What is the brand name of bupivacaine?
- Marcaine
What is the brand name of succinylcholine?
- Anectine
During a spinal block, the needle causes pain in the leg. What would you do?
- Do not inject anything
- Withdraw the needle and redirect it more medially
During a spinal block, the needle hits the bone all the time. What would you do?
- Reposition the patient
- Change the needle — the tip of the needle is damaged from contact with bone
- Try a different interspace or paramedian technique
- Remember that the risk of spinal hematoma is increased in patients with spinal stenosis
- Therefore, if you are not able to find the subarachnoid space, change the anesthesia method and do not stubbornly persist with further attempts at lumbar puncture
During a spinal block, the needle hits the bone early in the procedure. What would you do?
- The needle is contacting the spinous process
- Point the needle slightly caudally
During a spinal block, the needle hits the bone late in the procedure. What would you do?
- The needle is contacting the lamina
- Point the needle slightly cephalad
What is a “Total or High” Spinal?
- Unexpected spread of local anesthesia extending into high cervical and cranial nerves
What can a total or high spinal block lead to?
What would be an early symptom of this?
- Apnea
- Unconsciousness (Depressed RAS)
- Loss of motor function to upper extremities
- Severe hypotension or bradycardia
- Inability to PHONATE (Early Symptom)
What are the possible causes of Total or High Spinal Block?
- Excessive dosing of local anesthetics
- Failure to reduce doses in selected patients (elderly, obese, and very short)
- Rapid injection of LA in SAB (Barbotage)
- Improper positioning after placement of SAB
- Unrecognized intrathecal placement of epidural catheter
- Can occur in properly placed epidural
What are interventions for a total or high spinal block?
- If the patient can phonate, the block probably isn’t high enough to require intubation.
- Treatment is supportive
- Treat hypotension with vasopressors aggressively
- Airway, oxygen, CPAP, and intubation (general anesthesia) if necessary
- Canceling the case is indicated if unable to maintain normal resp and CV status
Prevention of “Total or High” Spinal
- Careful dosing of LA (Frequent dermatome assessment)
- Early recognition of inadvertent intrathecal catheter placement
- Adequate assessment of the epidural “test dose.”
- Slow, incremental dosing epidural
- Awareness of the patient’s position after SAB is placed (be vigilant)
Dyspnea is associated with high dermatome blocks. What patient positioning is indicated and may be helpful?
- Reverse Trendelenburg
What is a Postdural Punctured Headache (PPHD)?
- Failure of a dura puncture site to properly “seal over” once breached by a needle
- Continuous leak of CSF causes an overall reduction in CSF volume
- This reduction in volume cause“renting” (collapse) and stretch on the dura
The dura has a large amount of pain-afferent fibers that generate a headache (frontal or occipital)
With a Postdural Puncture Headache, what posture will exacerbate the dura stretch producing a profound and debilitating headache?
- Upright posture
What are the risk factors of PDPH?
- Age- Elderly = lower the risk (tougher ligaments in elderly patients)
- Large gauge needle
- Using a cutting needle
- Women
- History of previous post-dural headache
- Multiple dural punctures
Differentiate the size of the needle used SAB vs. Epidural Block.
- SAB: 25 gauge
- Epidural Block: 18-19 gauge
With PDPH, low CSF will lead to cranial nerve traction. What nerves are affected?
- CN VI (Abducens Nerve)- diplopia, double vision
- CN VIII (Vestibulocochlear Nerve)- tinnitus, ringing of the ears
What can happen d/t cerebral vasospasm caused by cerebral hypotension from dura puncture?
- Seizures
What treatments for PDPH?
- Supine relieves HA but does not hasten resolution
- NSAIDs, narcotics (fentanyl) useful for mild HA
- Methylxanthine derivatives (caffeine) for mild HA (300 - 500 mg PO or IV)
- When using caffeine, caution for elderly and those who can not tolerate CNS/cardiac stimulation
- Blood patch (If PDPH is not resolved within 24-48 hrs)
How much blood is used for the blood patch?
How does a blood patch treat PDPH?
Where will you insert your needle for a blood patch?
- 20 ml of blood is taken from the patient’s arm
- Blood will clot and occlude the perforation, preventing further CSF leak.
- Either one level higher or lower of dural puncture, blood is injected into the epidural space while the patient is in the lateral position.
The blood patch procedure will be painful; make sure to provide analgesia.
Transient neurological symptoms (radiating back pain) from neuraxial anesthesia are secondary to what local anesthesia?
When does it develop?
What is the incidence rate?
- Lidocaine 5%
- Develops immediately after the block resolves
- Incidence rate: 11.9%
Transient neurological symptoms usually resolve within a week for 90% of cases.
What is the cauda area referring to?
- L1-S4 + coccygeal nerves
What is cauda equina syndrome, and what is it associated with?
- Serious neurologic complications/damage to the cauda area that can be permanent, leading to paraplegia.
- Associated with spinal microcatheters and high concentrations of local anesthetics (Lidocaine 5% SAB).
Using microcatheters and local anesthetics causes pooling of LA in the cauda equina area.
What are the symptoms (red flags) of cauda equina syndrome?
What symptom is considered a late sign?
- Bowel/Bladder dysfunction
- Paraplegia (late sign)
- Back pain
- Saddle anesthesia
- Sexual dysfunction
If compression (disc, hematoma) is the factor causing Cauda Equina Syndrome, what is the immediate intervention (< 6 hours)?
- Laminectomy
What are the auditory, facial, and ocular complications of SAB?
- Transient hear loss d/t changes in CSF pressure
- Horner’s syndrome
- Trigeminal nerve palsy (ganglion bathed in CSF)
What are the signs and symptoms of Horner’s syndrome?
- Miosis (constriction of the pupil)
- Ptosis (drooping of the upper eyelid)
- Anhidrosis (absence of sweating)
What are the three branches of the Trigeminal Nerve (CN V)?
- V1 Ophthalmic
- V2 Maxillary
- V3 Mandibular
What three nerves need to be blocked in awake fiberoptic intubation?
- Trigeminal Nerve (specifically the maxillary nerve V2) - CN V
- Glossopharyngeal Nerve - CN IX
- Vagus Neve (specifically the recurrently laryngeal nerve) - CN X
How would you block V2 of the trigeminal nerve for awake intubation?
- Use a Q-tip and a local anesthetic to cause vasoconstriction (cocaine).
How would you block the glossopharyngeal nerve for awake intubation?
- Wrap the tip of a tongue depressor with gauze.
- Apply lidocaine paste to gauze and place in patient’s mouth for 5 mins.
How would you block the vagus nerve for awake intubation?
- Lidocaine is injected into the cricoid membrane.
- Once LA is in the trachea, the patient will cough to disperse the medication to block the recurrent laryngeal nerve.
What are the risk factors for epidural/spinal abscess?
- Untreated Bacteremia
- Immune depression (HIV, etc)
- Multiple needle attempts
- Long catheter duration
What are prophylactic measures for epidural/spinal abscesses?
- Antibiotic (cephalosporin)
- Hand washing
- Strict sterile technique
- Chlorhexidine + Alcohol
Epidural/Spinal abscess can lead to meningitis which has a ____% mortality rate.
- 30%
Arachnoiditis is inflammation of the meninges associated with what three factors?
- Nonapproved administration of a drug into intrathecal or epidural space.
- Using non-preservative-free solutions
- Betadine contamination (most common cause, please wipe off)
Arachnoiditis can lead to extensive sclerosis of arachnoid membranes and constriction of the vascular supply
What is the overall incidence of epidural/spinal hematoma?
1 in 200K
What is epidural/spinal hematoma associated with?
- Preexisting abnormalities in clotting hemostasis (Ask pt if they are taking anticoags)
- Traumatic or difficult needle placement (limit to 3 attempts)
- Indwelling catheters and long-term anticoagulation
With epidural/spinal hematoma, cord ischemia is reversible if laminectomy is performed in less than ______ hours.
- 8 hours
Need for prompt diagnosis and intervention
Symptoms of epidural/spinal hematoma
- Numbness/weakness (This can be confused by the effects of LA)
- Pain is a major symptom
- Paralysis between 24-48 hours
Systemic toxicity from neuraxial anesthesia is more common with ______.
- epidural anesthesia (more prone to hit the blood vessels)
