Complications in Obstetric Anesthesia

Report
Common Complications in
Obstetric Anesthesia–
and How to Avoid Them.
Tom Archer, MD, MBA
UCSD Anesthesia Resident Lecture Series
January 23, 2013
My definition of “common”
• A complication you will see at least once in a
career in which you do some OB anesthesia.
• If you do OB anesthesia regularly, you will see
most of the following complications many,
many times.
Common OB Anesthesia Complications
• Difficulty placing spinal or epidural,
causing patient distress.
• “Sketchy-dural” (poor epidural)
• Post-dural puncture headache (PDPH)
• Hypotension after neuraxial block
Common OB Anesthesia Complications
• High spinal or epidural respiratory failure +/hypotension
• Low spinal or epidural  anesthesia failure
• Intraoperative pain (incomplete block)
• Can’t intubate (and can’t ventilate?) under GA.
Common OB Anesthesia Complications
• Fetal bradycardia after CSE or epidural
• Post-delivery lower extremity neuropathy
I am not going to discuss:
• Local anesthetic or contaminant toxicity to
nerves (rare in modern practice).
• Direct needle trauma to nerve roots or spinal
cord (rare).
• Epidural abscess or hematoma (rare).
• Aspiration
Difficulty placing spinal or
epidural, with patient distress.
Difficulty placing spinal or epidural,
with patient distress.
• We have all been there, many times. At least I
have.
• 20-60 minutes of effort.
• Patient is in tears. You are sweating.
• You have called for help. They couldn’t do it
either.
• Is this inevitable, or is there a way to reduce
the frequency of such events?
Making epidural placement easier
for patient and doctor
• “Management of expectations”: “5-10% of the
time the epidural does not work properly. We
will do our best…” Don’t promise perfection!
• Achieve patient rapport and cooperation.
• Demonstrate posture.
• Reinforce positioning– patients straighten up
over time when in pain.
• IV fentanyl makes a big difference.
Making epidural placement easier
for patient and doctor
• If you anticipate difficult placement (e.g. an
obese patient) consider IV fentanyl and
ultrasound before you start.
• Don’t wait until patient is in tears to give
fentanyl and to use ultrasound.
Can ultrasound make
neuraxial block easier?
• Many practitioners say it is an unnecessary
waste of time. I disagree, at least in selected
cases.
• Ultrasound can help identify:
– MIDLINE (true location of spinous processes)
– DEPTH TO LIGAMENTUM FLAVUM
– SPINAL ROTATION, IF PRESENT
Paramedian Sagittal
Paramedian Sagittal
Oblique
Transverse
Most useful
views
Spinous processes
are not always
directly cephalad
from gluteal cleft
Tense paraspinous
muscles can be
mistaken for spinous
processes
Line running
cephalad from
gluteal cleft
PLL
D
LF
Skin surface
Emitted sound
Vertical
skin mark
Reflected sound
Ultrasound
probe,
lateral view
Transverse
process
PLL
D
LF
Skin surface
Emitted sound
Reflected sound
Best insertion angle is determined for each patient by
maximizing brightness of posterior longitudinal
ligament (PLL) on the ultrasound screen and
remembering that angle for actual needle insertion.
Best angle is usually 5-15 degrees cephalad from a
line perpendicular to the skin.
Ultrasound
probe is
angled until
posterior
longitudinal
ligament is
the
brightest.
Dura /ligamentum
flavum complex
Interlaminar foramen (black
shape inside white rectangle)
Posterior longitudinal
ligament
Vertical skin mark #1,
centered on probe
Horizontal skin mark #2,
centered on level of
probe (between spinous
processes)
Underlying spinous
process (dark blue)
Insertion point is the
intersection of
horizontal and vertical
lines through skin
marks.
Line running
cephalad from
gluteal cleft
PLL
D
LF
Skin surface
10 cm
Ultrasound enables us to measure distance to
the ligamentum flavum to within a centimeter
or so. Estimate, if incorrect, is almost always
too small, due to compression of adipose
tissue during the measurement.
Ultrasound
probe
Best
insertion
angle
“Sketchy-dural” (poor epidural)
“Sketchy-dural”
• They happen, no matter how good you are.
• “Management of expectations.” Don’t promise
the patient a perfect epidural.
• That said, here is my advice to minimize
impact of sketchy-durals on our care…
“Sketchy-dural”
• Be honest with yourself. Many sketchy-durals
are simply not in the right place.
• Check what is really going on, with ice–
systemic fentanyl can mask a non-epidural.
• Have a low threshold for replacement.
“Sketchy-dural”
• A disadvantage of IV fentanyl is that the
analgesia it provides can mask a poor
epidural.
• Ask the patient how her legs feel. The answer
should be “numb” or “tingly”. “Fine” is NOT a
good answer– it means there is no block!
• Epidurals requiring more than one MD bolus
have a higher failure rate for CS.
“Sketchy-dural”
• What exactly is the problem? Talk with and examine
the patient.
• Just doesn’t work at all? replace
• One sided? bolus with less-affected side down.
Next step pull back one cm. Next step replace
• “Hot spot” but otherwise OK? Position side with
“hot spot” downwards and bolus with stronger local
anesthetic + epinephrine + fentanyl.
“Sketchy-dural”
• Think about other causes of “abnormal” pain fetal
head pressing on nerves, uterine rupture, placental
abruption, “intradural placement.”
• There should be no pain (or much sensation at all)
with an epidural injection.
• Discomfort in the back during epidural injections
suggests intramuscular or subcutaneous injection.
“Sketchy-dural”
• Consider ultrasound the second time (or the first
time!) to confirm:
– MIDLINE (true location of spinous processes)
– DEPTH to ligamentum flavum
– ROTATION of the spinal column
“Sketchy-dural” goes to CS.
• Can you do a spinal on top of a “sketchydural”?
• Yes, but do it carefully and understand that
high spinal may occur.
• CSE with low intrathecal dose, or titrated
epidural are options.
Post dural puncture headache
(“Spinal headache”)
Post dural puncture headache
(PDPH)
• Third most common cause of lawsuit in OB
anesthesia.
• Can be disabling and distressing, particularly
for a mother trying to take care of a newborn
and a household.
Post dural puncture headache
(PDPH)
• Third most common cause of lawsuit in OB
anesthesia.
• Can be disabling and distressing, particularly
for a mother trying to take care of a newborn
and a household.
PDPH
• Midline frontal and/or occipital. Not lateralized!
• May extend into neck (stiff neck)
• Worse with upright posture (usually immediate
onset, may be delayed 20 minutes)
• Relief with flat posture (usually immediate).
PDPH
• May be associated with diplopia (abducens
palsy) and muffled hearing or tinnitus.
• May be associated with N+V.
But is it really PDPH?
• The key question: Could it be something else?
• If you Rx PDPH and it is something else you
incur two problems: unnecessary treatment
risk AND missed Dx.
• It could be: lactation HA, migraine, subdural
hematoma, brain tumor, AVM, cortical vein
thrombosis, dural sinus thrombosis, etc.
Yes, it is PDPH
• Conservative therapy vs. Blood patch?
• Conservative therapy: NSAIDs, other oral
analgesics, caffeine, fluids, salty foods.
• Epidural blood patch (EBP): 10-30 mL of
patient’s blood injected into epidural space.
• EBP complications: back pain, leg paresthesias
(common), epidural abscess or adhesive
arachnoiditis (rare).
In favor of EBP
• Severe disability, >24 hours of Sx.
• Patient confined to bed– unable to function
• Associated signs + Sx of decreased ICP
(abducens palsy, hearing changes, N+V)
In favor of conservative therapy
• Uncertain Dx.
• Patient uncomfortable but able to function.
• If they are sitting up in bed, or walking, when I
enter the room, I am hesitant to do a blood
patch.
PDPH etiology
• Traditional theory: loss of CSF leads to brain “settling
down” in skull, with resultant traction on dura and
nerves
• Vasodilation theory: loss of CSF leads to translocation
of CSF to lumbar area with upright posture. Volume
in skull must remain constant, hence vasodilation
+ HA.
• Therapeutic efficacy of caffeine and vasoconstrictors
supports vasodilation theory
Hypotension after labor epidural
Hypotension after labor epidural
• Occurs VERY commonly. 30-40% of the time?
• Consider low dose prophylactic phenylephrine
or ephedrine after block placement.
Hypotension after labor epidural
• 95% of fetal distress after epidural is due to
hypotension.
• The other 5% may be “uterine hypertonus”
due to rapid pain relief (discussed later).
• Both things might be happening.
• When there is fetal distress palpate uterus!
Hypotension after labor epidural
• Routine therapy for hypotension (in absence
of uterine hyperstimulation) is:
Position change (Left or right side down).
Fluid bolus
Vasopressors
Oxygen, if there is fetal bradycardia.
Hypotension with labor epidural
• Treat hypotension early, treat often.
• Prevention with low-dose vasopressor has
very little downside.
• Is there a role for non-invasive cardiac output
measurement in labor to detect occult IVC
obstruction?
Physiology of post-block
hypotension
Sympathetic efferents exit
spinal cord from T1 to L2.
Low sympathectomy:
Blockade of T5-L2
Splanchnic vasodilation
and pooling. Reduced
venous return (CO),
especially with IVC
obstruction. Reduced SVR.
17
http://health.usf.edu/nocms/medicine/anatomylab/modules/pelvic_autonomic_module/pelvic_page02.html
Sympathetic efferents exit
spinal cord from T1 to L2.
High sympathectomy:
Blockade of T1-T4  warm
vasodilated hands, further
reduced SVR, Horner’s
syndrome, ? bradycardia.
Blockade of T5-L2
Splanchnic vasodilation
and pooling. Reduced
venous return (CO),
especially with IVC
obstruction. Reduced SVR.
18
http://health.usf.edu/nocms/medicine/anatomylab/modules/pelvic_autonomic_module/pelvic_page02.html
T5-L2 sympathectomy causes pooling of blood in the splanchnic
vessels, reducing venous return and CO.
20
Splanchnic vasculature has alpha and beta receptors at multiple sites.
Beta 2 dilates
hepatic veins
Alpha 1+2
constrict
splanchnic
capacitance
vessels
Alpha 1+2 constrict
splanchnic arteries
21
Figure modified by Archer TL
Decreased venous return and
cardiac output due to sympathectomy
is exacerbated by obstruction of IVC.
22
If IVC is open, venous return is unimpeded
and cardiac output is maximized.
23
http://www.manbit.com/OA/f28-1.htm
Manbit
images
Given late!
29
Diagram modified by Archer TL
Avoid cardiac arrest
after neuraxial block
• Talk with patient during test dose. “Heart pounding, legs
numb or weak?” Have Ambu bag and pressors
immediately available.
• Allow 2-3 minutes for test dose to be positive. Consider
dosing epidural fentanyl 100 mcgm after test dose since
it will augment block but not “burn any bridges.”
• Stay with patient 15-30 minutes after initiation of block to
r/o hypotension, hyperstimulation or excess block. Do
charting. Start infusion. Make sure nurse will stay with
patient after you leave.
30
Cardiac arrest in labor room– do
the CS in the labor room!
• “Four minute rule”– start CS within 4 minutes
of arrest. Deliver baby within 5 minutes to
avoid neonatal brain damage.
• “Our findings imply that perimortem cesarean
delivery during actual arrest would require
more than 5 minutes and should be
performed in the labor room rather than
relocating to the operating room.”
Obstet Gynecol. 2011 Nov;118(5):1090-4.
Labor room setting compared with the operating room for simulated perimortem cesarean delivery: a randomized controlled trial.
Lipman S, Daniels K, Cohen SE, Carvalho B.
33
High spinal (or epidural)
Sympathetic efferents exit
spinal cord from T1 to L2.
High sympathectomy:
Blockade of T1-T4  warm
vasodilated hands, further
reduced SVR, Horner’s
syndrome, ? bradycardia.
Blockade of T5-L2
Splanchnic vasodilation
and pooling. Reduced
venous return (CO),
especially with IVC
obstruction. Reduced SVR.
18
http://health.usf.edu/nocms/medicine/anatomylab/modules/pelvic_autonomic_module/pelvic_page02.html
High or Total Spinal
• A circulatory as well as respiratory
emergency.
• You will have to assist or control ventilation.
• You must recognize situation immediately and
act rapidly and with confidence so that patient
does not panic (too much).
High or Total Spinal
• Say three things:
– “You’re going to be OK.”
– “This happens sometimes when the spinal
goes too high.”
– “I’m going to help you breathe.”
High or Total Spinal
• Do this:
• Unwrap circle system tubing and mask and
close down pop-off valve.
• Put mask on face and assist ventilation.
Explain what you are doing. Patient is
panicking.
High or Total Spinal
• Do this:
• Feel for a pulse and if weak (or just
empirically) give ephedrine 10-25 mg.
Atropine for bradycardia.
• Check BP, but all that really matters is
ventilation and a good pulse.
High or Total Spinal
• Should you intubate?
• It depends, but ventilation trumps intubation.
• Ventilation even trumps aspiration.
• My rule of thumb: LOC, total apnea intubate.
But stabilize BP and oxygenation first, even
before intubation!
Low spinal
Low spinal
• Hyperbaric (bupivacaine) solution will “pool”
in the dural sac below the sacral promontory if
patient is allowed to sit for too long after the
intrathecal injection.
• Trendelenburg position often used “to move
level up”– but no proof it really works.
Low spinal
• Cough often used “to move level up”-- but no
proof it really works.
• T’burg + flexion of thighs on the abdomen–
straightens lumbar curve and raises intraabdominal pressure.
• I believe this works.
Seated injection and prolonged
upright posture allow pooling
of hyperbaric solution
Hyperbaric
solution
injected
here can
pool here
Modified from Delaney Radiologists
Supine position
Sacral promontory can be a
barrier to cephalad spread
Avoiding a low spinal
• Have patient lie down rapidly after intrathecal
injection. Have her position herself on the OR
table. Trendelenberg? Cough?
• Flexion of thighs on the abdomen to flatten
lumbar curve and to increase intra-abdominal
pressure.
Image from Boba, Inc.
Repeat the spinal?
• Bupivacaine takes 15-20 minutes for full
effect, so don’t rush it.
• Beware of high or total spinal if you repeat the
injection.
• How’s the airway?
• Epidural may be better.
Fetal bradycardia
after neuraxial analgesia
Fetal bradycardia
after neuraxial analgesia
• Classic scenario for hypertonic uterus is: Patient
has oxytocin augmentation of labor and severe
pain. CSE with lipid soluble narcotic is given
rapid pain relief. Fetal bradycardia occurs 10-30
minutes after the block. Loss of beta stimulus?
• May or may not be accompanied by hypotension,
but hypertonic uterus is a separate
phenomenon, requiring uterine relaxation.
Correction of BP is not enough!
Figure 2 Uterine contractions periodically deprive placenta of perfusion.
Upper body
Open
IVC
Minimal collateral
venous return to
heart via lumbar and
azygos system
Fetal O2
supply
Uterine contractions
Uncompressed
aorta and iliac
arteries
Uterine hyperstimulation due to excessive oxytocin augmentation of labor—
Solution is NOT always emergency CS.
Rather, it is INTRAUTERINE RESUSCITATION using TIME and TERBUTALINE or
NTG
Tak Yeung Leung, MDa, b, , (Professor),
Terence T. Lao, MDa (Professor)
Detecting uterine hyperstimulation
• Key “maneuver” is to think of the possibility
and to evaluate uterine tone by palpation or
IUPC during fetal bradycardia.
• Recognition of uterine hyperstimulation and
reversal with terbutaline SC or NTG SL or IV
can avoid an unnecessary CS!
Intraoperative pain during CS
Intraoperative pain during CS
• “Management of expectations”– don’t
promise a pain-free experience.
• Discuss intraoperative pain management
options ahead of time. What will patient
tolerate?
• Mild discomfort fentanyl + local infiltration?
Intraoperative pain during CS
• More discomfort Fentanyl, midazolam +
ketamine (low dose and maintain
responsivenss). Keep your suction at the
ready.
• Severe discomfort RSI/ GA.
Choice of neuraxial technique
when airway is bad.
• Consider avoiding CSE if airway is bad:
epidural may fail, leaving patient with surgery
underway and disappearing block.
• If airway is bad, straight epidural or
continuous spinal anesthesia may be a better
choice than CSE, since you know it works from
the outset, before surgery starts.
Can’t intubate under GA
Can’t intubate under GA
• A few comments only:
• 1) Pregnancy involves weight gain and airway
edema.
• 2) Pre-eclampsia and pushing make 1) worse.
• 3) Nose bleeds easily in pregnancy.
Can’t intubate under GA
• 4) Position every patient assuming you will have to
intubate her (e.g. ramp, Glidescope, etc, available if
need foreseen).
• 5) Avoid CSE if airway is unfavorable for intubation. The
reason is: epidural part of CSE may fail when you try to
activate it.
• 6) Continuous epidural or spinal is better if airway is bad.
That way you know anesthesia will work as long as you
need it, before surgery starts.
Management of
“can’t intubate” situation
• Elective procedure awaken patient and
secure airway by other means (e.g. AFOI).
• Emergency procedure LMA?, careful
ventilation, good paralysis (avoids coughing
and retching).
Post-delivery lower extremity
neuropathy
Post-delivery lower extremity
neuropathy
• “Post-delivery” does not = “Due to anesthesia”
• Vast majority of post-delivery neuropathies are
due to nerve stretch, pressure, compression or
ischemia– not due to needle damage or local
anesthetic toxicity.
• “Obstetric palsy”– from fetal head, forceps or
positioning. Often seen without anesthesia.
Post-delivery lower extremity neuropathy
• So, relax when you see these patients!
• You probably did not (directly) cause it-- and it
will almost certainly resolve over time.
• On the other hand– listen well, be sympathetic
and get proper consultation and therapy.
• Do not be dismissive of the problem!
Post-delivery lower extremity neuropathy
• Take a good history and do a good physical.
• Rule out signs and symptoms of meningitis,
spinal hematoma or infection.
• Do not hesitate to get Neurology consultation.
• Stay in touch with the patient.
Obstetric palsy
• From nerve compression within the pelvis, by
fetal head, forceps or retractors.
• Often blamed on neuraxial anesthesia.
Pelvic brim is the red line.
Fetal head is “engaged” when biparietal diameter is below pelvic brim.
Fetal head or forceps can damage nerves (lumbosacral trunk or obturator) at
sacral promontory portion of pelvic brim.
http://www.obstetricexcellence.com.au/questions-and-answers/engagement-of-the-foetal-head
Pelvic brim
Peripheral nerves in the pelvis.
Pelvic brim
Dote Anatomy Topics
Vulnerable nerves in
pelvis:
Lateral femoral
cutaneous (at inguinal
ligament)
Lumbosacral trunk
Obturator
Femoral
Sciatic
Cited in Wong et al
Safeguards to Minimize
Peripheral Nerve Compression
•
Be watchful for patient positioning that contributes to nerve
compression…
•
Avoid prolonged use of the lithotomy position; regularly reduce hip
flexion and abduction.
•
Avoid prolonged positioning that may cause compression of the
sciatic or peroneal nerve.
F. Reynolds in Chestnut
Safeguards to Minimize
Peripheral Nerve Compression
•
Place the hip wedge under the bony pelvis rather than the buttock.
•
Use low-dose local anesthetic/opioid combinations during labor to
minimize numbness and allow maximum mobility.
•
Encourage the parturient to change position regularly.
F. Reynolds in Chestnut
Peripheral Neuropathy Syndromes
in Obstetrics
• “Meralgia Paresthetica”– lateral femoral
cutaneous nerve (pure sensory)– numbness of
lateral thigh. Common in pregnancy.
• Femoral nerve damage from prolonged hip
flexion weak quadriceps. Can’t straighten
leg and climb stairs.
Peripheral Neuropathy Syndromes
in Obstetrics
• Foot drop– Impaired foot dorsiflexion due to:
– Common peroneal nerve at fibula (leg holders)
– Lumbosacral trunk at pelvic brim (fetal head)
• Impaired dorsi- and plantar-flexion of foot and numbness
below knee: Sciatic nerve damage. Pressure on buttock
during long CS? Diabetic patient?
• Impaired adduction of thigh and inner thigh numbness–
obturator palsy at pelvic brim
The End
Extra slides
Spinal nerve “roots” are within the spinal canal. Dorsal root ganglion is at intervertebral
foramen.

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