Spinal & Epidural Flashcards
(44 cards)
spine anatomy
cervical = 7 thoracic = 12 lumbar = 5 sacral = 5
components of the vertebrae
- vertebral body
- pedicle x2
- transverse process x2
- lamina x2
- spinous process
- superior articulating process x2
- inferior articulating process x2
what do the articular processes make?
- zygapophyseal joints
- when stacked make the intervertebral foramina
spinal cord termination
- adults: L1-L2
- children: L3
ligaments of the spinal column
- supraspinous: joins apexes of spinous process, major ligament in cervical and thoracic
- interspinous: thin, joins spinous process
- ligamentum flavum: helps maintain posture, 3-5 mm, yellow color
membranes of the spinal column
- dura: outermost, thick, protection
- arachnoid: thin, closely associated with dura
- pia: thin, directly covers the spinal cord
average lumbar AP distance of epidural space
5 mm
epidural space
- runs entire length of spine
- segmented but interconnected
- contains: blood vessels, fat, lymphatics, nerve roots
spinal blood supply arteries
- one anterior spinal artery: anterior 2/3 of cord, from vertebral artery
- two posterior spinal arteries: posterior 1/3 of cord, from cerebellar arteries
- segmental spinal arteries: artery of adamkiewicz, lower anterior 2/3 of cord
spinal blood supply veins
- 3 anterior spinal veins
- 3 posterior spinal veins
-communicate with epidural veins
specific gravity of CSF
1.004-1.009
absolute contraindications to spinal anesthesia (3)
- patient refusal or inability to remain still
- increased ICP
- localized sepsis
relative contraindications to spinal anesthesia (6)
- previous spinal surgery
- aortic stenosis
- hypovolemia
- thromboprophylaxis
- coagulopathies
- infection
differential blockade
- sympathetic: 2 dermatomes above sensory
- sensory: 2 dermatomes above motor
- motor
block level - epidural versus spinal
epidural: more volume moves block higher
spinal: moves based on specific gravity of drug
spinal blockade mechanism of action
- primary: spinal roots
- secondary: spinal cord, brain
baricity
-the ratio of the local anesthetic to the CSF specific gravity
- hyperbaric > 1.015, add glucose
- normobaric = 1, NS or CSF
- hypobaric < 0.999, add water
factors that control spread of local anesthetic (4)
- dose
- baricity
- patient position
- injection site
spinal - cardiovascular effects
- sympathetic fibers arise from T5-L1
- sympathetic cardioaccelerator fibers arise from T1-T4
- increased arterial dilation, venous pooling
- decreased SVR, preload
bainbridge reflex
- unopposed vagal tone slows the heart rate
- cardioaccelerator fibers arise from T1-T4
spinal - cardiovascular treatments
- fluids
- alpha or beta agonists
- serotonin antagonist
- atropine (if high spinal)
spinal - respiratory effects
- loss of accessory muscles, perception of breathing
- decreased vital capacity
- impaired cough
- phrenic nerve (C3-C5)
spinal - other effects (GI, stress, thermoregulation)
- GI: unopposed vagal tone, increased peristalsis, relaxed spincters
- decreased thermoregulation
- decreased stress response
total spinal symptoms
- restlessness
- hypotension
- bradycardia
- apnea
