neuraxial blocks part 2 Flashcards
4 key SE of neuraxial opioids
- pruritis
- urinary retention
- resp depression
- n/v
MOA of pruritis during neuraxial blockade
stimulation of opioid receptors in trigeminal nucleus or some other type of opioid triggered neural process
MOA of early versus late stage resp depression (most often both in hydrophilic)
early (<6h) results from systemic absorption
late (>6h) results from tendency of hydrophilic opioids to ascent towards brainstem where they can inhibit resp center
resp depression is more common with (6)
high opioid doses
co administered sedatives
low lipid solubility
advanced age
opioid naivety
increased ITP
urinary retention from neuraxial opioids MOA
inhibition of sacral PSNS tone aka SNS tone is winning
n/v from neuraxial opioids MOA
caused by activation of opioid receptors in the area postrema of medulla and vestibular apparatus
transfer of opioids from epidural space to breast milk
minimal
which LA decreases efficacy of neuraxial opioids
2 chlorprocaine
neuraxial blocks are contraindicated if platelet count is what and coags are
platelet count <100,000
coags are 2x normal value (aPTT, PT, or bleeding time)
contraindications to neuraxial opioids include
-increase in ICP
-sepsis
-infection at puncture site
-hypovolemia
-valve lesions with fixed SV
-scoliosis, arthritis, spinal fusions, osteoporosis
-full stomach
-peripheral neuropathy (theory that patients are more susceptible to injury)
-MS
-spina bifida
ID this type of spinal needle
quincke
ID this type of spinal needle
sprotte
ID this type of spinal needle
whitacre
ID this type of spinal needle
green
ID 3 types of spinal needles
cutting tip (quincke)
pencil point (sprotte, whitacre)
rounded bevel (green)
ID these 3 types of epidural needles
how deep is epidural space
3-5cm from skin surface
absolute contraindications to caudal anesthesia
spina bifida
myelomeningocele of sacrum
meningitis
relative contraindications to caudal anesthesia
pilondial cyst
abnormal superficial landmarks
hydrocephalus
intracranial tumor
progressive degenerative neuropathy
caudal block technique
position of patient
landmarks
needle type
-performed in lateral or prone position
-in lateral position (Simms) top leg flexed more than bottom leg
-in prone position, small roll should be placed under iliac crests with legs in frog position
-using PSIS and sacral hiatus as land marks, envision equilateral triangle with apex of triangle at sacral hiatus
-use 22 or 25g needle or 20g IVC at 45 degree angle angling cephalad
-advance until you hear a pop then drop the angle and advance
you should not use ______ for loss of resistance in children during epidurals
air (risk of air embolism)
resistance to injection during caudal block suggests needle is in
subperiosteal area
what feeling may patient experience as a caudal epidural is setting up
feeling of fullness in sacrum
placing the needle tip beyond ______ increases the risk of of dural puncture during caudal block
S2-S3
during a caudal block, how to you angle the needle
once you feel a pop, drop the angle from 45 degrees
how to dose a caudal block
pediatric
adult
peds: .5mL/kg
adult 12-15mL
how to dose a sacral to low thoracic block (T10)
pediatric
adult
peds: 1mL/kg
adult: 20-30mL
how to dose a sacral to mid thoracic anesthetic
pediatric
adult
peds: 1.25mL/kg
adult: n/a
peds dose maximums for caudal block
dont exceed total dose of 2.5-3mg/kg
common procedures where a caudal block is useful
circumcision
hypospadias repair
anal surgery
inguinal herniorrhaphy
low thoracic surgery
presenting symptoms of epidural hematoma
LE weakness, numbness, low back pain, bowel and bladder dysfunction
surgical decompression within 8 hours is the best chance of recovery
risk of epidural hematoma is similar during block placement and catheter removal
