Neuraxial blocks 5 Flashcards
You are called to remove an epidural catheter form a patient receiving enoxaparin for DVT prophylaxis. According to the consensus statement from the American Society for Regional Anesthesia and Pain medicine, what is the MOST appropriate course of action?
a. hold enoxaparin for six hours, pull catheter, then restart enoxaparin one hour later
b. hold enoxaparin for 12 hours, pull catheter, then restart enoxaparin four hours later
c. hold enoxaparin for 24 hours, pull catheter, then restart enoxaparin two hours later
d. order a hematology consult
B.
The risk of________________ is similar during block placement and catheter removal
epidural hematoma
Epidural hematoma can cause
paralysis
________________within eight hours of epidural hematoma offers the best chance of recovery
surgical decompression
Presenting symptoms of epidural hematoma include
lower extremity weakness, numbness, low back pain, and bowel and bladder dysfunction
These patients present with a difficult situation in terms of holding vs. continuing antiocoagulation.
patients with cardiac stents
Describe the recommendations for a patient who is on Cox-1 inhibitors (NSAIDs, aspirin).
if clinical assessment of coagulation status appears normal and no other blood thinners in use then no added risk or limitations
Describe the recommendations for a patient who is on glycoprotein IIb/IIIa antagonists (abciximab, tirofiban).
avoid until platelet function has recovered
-before block placement: hold 4-8 hr for Tirofiban and eptifibatide ; hold 24-48 hour for abciximab
contraindicated to not restart within 4 weeks of surgery
Describe how long clopidogrel should be held prior to block placement.
hold 5-7 days
may restart 24 hours postop
Describe how long prasugrel should be held prior to block placement
hold 7-10 days
may restart 24 hours postop
Describe how long ticlopidine should be held prior to block placement
hold 10 days
may restart 24 hours postop
Describe how long unfractionated heparin must be held prior to block placement
low dose 5,000 U up to TID: hold 4-6 hour
higher dose <20,000 U daily: hold 12 hour
Therapeutic high dose: hold 24 hour
Criteria to consider for a patient on heparin when placing or removing a neuraxial catheter is
obtain a platelet count prior if on IV or SQ heparin >4 days
How quickly can heparin be restarted after block placement?
1 hour
After neuraxial catheter removal, how long should heparin be held for?
held 4-6 hours after last SQ dose
held 4-6 hour after IV infusion discontinued
What drugs are an absolute contraindication to neuraxial anesthesia?
thrombolytic agents such as TPA, streptokinase, alteplase, urokinase
Is neuraxial anesthesia safe to perform for patients taking herbal therapies such as garlic, ginkgo, and ginseng, that inhibit platelet aggregation?
yes, proceed if patient is not taking other blood thinning drugs
Describe the recommendations for anti-vitamin K drugs such as warfarin.
before block/catheter placement: hold warfarin for 5 days, verify normal INR
neuraxial catheter removal: wait until INR <1.5
Describe considerations for before block/catheter placement when patient is on low molecular weight heparin.
delay at least 12 hr after prophylactic dose
delay at least 24 hour after therapeutic dose & consider checking anti-factor 10a activity in elderly or if renal insufficiency
Describe when it is acceptable to restart LMWH after block/catheter placement.
delay first dose at least 12 hours after block
if single daily dosing, give 2nd dose no sooner than 24 hours after 1st dose
If you have blood in the needle or catheter of a patient on LMWH,
delay initiating LMWH for 24 hour
When removing a neuraxial catheter for a patient on LMWH,
remove before initiating LMWH if possible; delay 1st dose at least 4 hr after removal
otherwise, remove at least 12 hr. after last dose; hold for 4 hr after removal
Describe considerations for oral anti-factor 10a agents prior to block/catheter placement.
discontinue at least 72 hours (3 days) before the block
consider checking drug level or anti-factor 10a activity if <72 hours
When removing a neuraxial catheter for patients on oral anti-factor 10a agents,
remove 6 hours before the 1st postoperative dose
if accidental dose given with catheter in situ, hold subsequent dose before catheter removal for >20 hours
Which factors increase the risk of postdural puncture headache?
a. pitkin needle
b. needle perpendicular to the long-axis of the neuraxis
c. early ambulation
d. continuous spinal catheter
A & b
Describe the factors that contribute to PDPH.
puncturing the dura causes CSF to leak from the SAH
as CSF pressure is lost, the cerebral vessels dilate
the brainstem sags into the foramen magnum which stretches the meninges and pulls on the tentorium
The classic presentation of PDPH includes
a fronto-occipital headache which may be accompanied by nausea, emesis, photophobia, diplopia, and tinnitus
Selected factors that increase the risk of PDPH include
young age, female sex, and pregnancy
Treatment for PDPH includes
bed rest, caffeine, epidural blood patch (the definitive treatment), or a sphenopalatine ganglion block
________________ is one of the most common culprits responsible for post-spinal bacterial meningitis
streptococcus viridans
What is the most effective antiseptic when prepping the back?
alcohol and chlorhexidine
It is important to allow time for chlorhexidine to try because
it’s neurotoxic
These factors have no effect on the risk of PDPH
early ambulation
continuous spinal catheter
If the headache does not improve after two blood patches,
you should consider other etiologies
Describe how to perform an epidural blood patch.
Using sterile technique, 10-20 mL of venous blood is withdrawn from the patient and then reintroduced into the epidural space.
When the patient senses pressure in the legs, buttocks, or back, the injection is complete
The most common side effects of epidural blood patch are
backache and radicular pain
Describe why a blood patch is useful.
it compresses the epidural and SAH spaces, which increases CSF pressure
and it acts as a plug that prevents further leaks
Describe how to perform a sphenopalatine ganglion block
soak a long cotton-tipped applicator in a local anesthetic solution
place the patient in the sniffing position
insert the applicator into each nare towards the middle turbinate
continue insertion until you encounter the posterior wall of the nasopharynx
leave the applicator in place for 5-10 minutes
the patient should notice symptom improvement at this time
When placing a neuraxial block, what two routes may cause an infectious organism to reach the CSF?
failure of aseptic technique
bacteria in the patient’s blood at the time of SAB
Following the resolution of a subarachnoid block, the patient complains of severe pain in the buttocks that radiates through her legs. She has normal motor function. What should be said to the patient?
a. this was due to the use of a spinal microcatheter
b. avoid bupivacaine if you have another spinal anesthetic in the future
c. most patients will experience pain for one month
d. ibuprofen will help your pain.
d.
Preventative measures against spinal-induced hypotension include
volume loading, vasopressors, ondansetron, and pelvic tilting
Cauda equina syndrome is caused by
neurotoxicity from exposure to high concentrations of local anesthetic
Factors that increase the risk of caudal equina syndrome include
5% lidocaine and spinal microcatheters
Signs and symptoms of cauda equina syndrome include
bowel and bladder dysfunction, sensory deficits, weakness, or paralysis
Treatment for cauda equina syndrome is
supportive
Transient neurologic symptoms can be caused by
patient positioning, stretching of the sciatic nerve, myofascial strain, and muscle spasm
Factors that increase the risk of transient neurologic symptoms include
lidocaine, lithotomy position, ambulatory surgery, and knee arthroscopy
Signs and symptoms of transient neurologic symptoms include
severe back and butt pain that radiates to both legts
Treatment for transient neurologic symptoms include
NSAIDs, opioid analgesics, and trigger point injections
The risk of spinal induced hypotension is increased by
a higher block >T5, age over 40 years, and pre block systolic blood pressure <120
The risk of bradycardia with spinals is increased by
pre-block bradycardia, male gender, younger age, and beta-blockade
_____________ is likely mediated by 5-HT3 receptors in the vagus nerve and ventricular myocardium.
Bezold-Jarisch
____________ is more effective in preventing hypotension (fluids)
Co-loading at 15 mL/kg
What is the BEST course of action when an epidural catheter breaks during its removal?
a. make a small incision to remove the retained fragments
b. consult a spine surgeon for surgical removal
c. order an MRI
d. leave it inside the patient
d.- as long as the patient remains asymptomatic, the likelihood of neurologic complications is very low
Blood return in an epidural needle or catheter suggests placement in an
epidural vein
If a spinal does not set up after 15-20 minutes, it is
reasonable to repeat the injection
If the patient has a unilateral block, you can position the patient
with the poorly blocked side down and administer several mL of local anesthetic. if this doesn’t work then consider another technique
If you encounter resistance when you try to remove the epidural catheter, then you should
place the patient in the original insertion position or the lateral decubitus position and apply gentle, continuous traction
Other possible fixes to removing a catheter that has resistance include
using a stylet to threat the catheter
injecting a wire-reinforced catheter with saline
tape the catheter to the skin under gentle traction and trying again later
Risk factors for epidural vein cannulation include
multiple insertion attempts
pregnancy (epidural vein engorgement)
sitting position
using a stiff catheter
trauma to the epidural veins during block placement
If you see blood in the needle, this is most likely caused by
too lateral of an insertion
The fix when you see blood in the needle is to
redirect the needle towards the midline
If you have blood in the catheter,
pull back the catheter a little and flush it with saline; you can repeat this procedure until you’re unable to aspirate blood or not enough catheter remains in the epidural space
The risk of venous cannulation is reduced by
injecting fluid in the epidural space before threading the catheter as well as using a wire-reinforced catheter
If you have a patchy spinal,
you should not repeat the spinal b/c of risk of neurotoxicity; instead you should transition to another technique
The most common cause of a unilateral epidural block is
that the catheter was inserted too far and the tip has exited the epidural space through an intervertebral foramen
Fixing a unilateral epidural block includes:
pull the catheter back 1-2 cm
position the patient in the lateral decubitus position (unblocked side down)
administering several mL of a dilute concentration of LA
if these don’t fix the problem, then you must replace the catheter
