spinal and epidural Flashcards
vertebral curves in supine position
high C5 L3
low T5 S2
ligamentum flavum
extends from foramen magnum to sacral hiatus
tough wedge shaped ligament compused of elastin
thickest in midline 3-5mm at L3 adults
“yellow ligament”
termination of spinal cord and dural sac
spinal cord (conus medullaris) L1-2 dural sac S2
T4
nipple
T6
xiphoid
T8
last rib
T10
umbilicus
CSF
150cc subarachoid space
volume replaced 3-4 times a day
production - 21 ml/hr by choroid plexus
spec gravity 1.004-1.008
blood supply
anterior spinal artery 2/3 blood flow
posterior spinal arteries
radicular artery
advantages of neuroaxial anesthesia
decreased metabloic stress response compared with GA
avoids airway instrumentation
decreased incidence post op N/V
less intraoperative sedation
post op pain relief
allows patient to remain awake for C section
disadvantages of neutoaxial anesthesia
hypotention
slower case start if challenging placeemnt
failure rate depends on experience
urban legends
considerations for choosing regional technique
anatomy (BMI, scoliosis, contractures)
age
pregnancy (reduced vol in epi space compression vena cava, L uterine displacement
patho (CV disease) - maybe unable to tolerate profound autonomic response
absolute CA
1) patient refusal
2) infection at inj site
3) increased ICP
4) clotting defects/anticoag therapy
5) severe hemorrhage/hypovol (autonomic response)
6) CNS disease, meningitis
7) hysteria/inability to remain still
8) bacteremia
9) septicemia
cardiovascular autonomic responses
blockade of autonomics
venous dilation > arterial dilation
SVR decreases 15-25%
CO decreases 10-15%
pulmonary SE
as block ascends, accessory muscle paralysis occurs, perception ineffective breathing
C3-5 phrenic nerve - tingling in pinky
GI SE
N/V hyperperistaliss, unopposed parasympathetic activity slow to liver renal lood lod autoreg bladder dysf unc
pencil point needle
spread dural fibers
reduces chances post epi HA
“pop”
greater tip strength
cutting (quince)
less likely to have “pop” bc sharper tip
increased risk post epi HA
tissue layers
skin subcutaneous tissue supraspinous ligament intraspinous ligament ligamentum flavum (epidural space) dura mater arachnoid mater (subarachnoid space) pia mater spinal cord
lumbar epidural
needle to LF, perpendicular angle
3.5-6cm
LOR
advance 2-3cm into epi space
hyperbaric solution
spec gravity > 1.11
mix with dextorose
hypobaric solution
spec gravity < 1.005
mix with sterile water
isobaric solution
spec gravity < 1.006
mix with CSF
factors affecting spread local in SAB
baricity position concentration and volume inj level injection barbotage/rage inj direction of needle and bevel
when can you be discharged?
spinal - pacu to floor after 4 dermatome regression < T10 stable and comfortable
SDS to home after ambulate w/o orthostatic and can void
caudal block
epidural space through sacral hiatus
sacrococcygeal ligament and sacral hiatus
22 or 23g needle and syringe
complications
hypotension brady cardiac arrest N/V intravascular inj intrathecal inj cathater shearing headach high blockade inadequate blockade neurological comp backache infection uriniry retention epidural hematoma
post dural puncture headache
younger female caucasian larger needle size pregnancy dehydration cutting tipped needle multiple puncture attempts
1-4% incidence
1 day to 1 week
bedrest ,hydrationm, oral analgesics, abd binder, caffiene, blood patch, saline inj
