Spinal Anesthesia Flashcards
What is the most important thing to have before administering your spinal?
patent IV
What are two other important things to have (besides patent IV) before you administer your spinal?
suction
ability to provide positive pressure ventilation
What is the order of anatomical structures traversed by a spinal needle?
- skin
- subcutaneous fat and tissue
- supraspinous ligament
- interspinous ligament
- ligamentum flavum
- epidural space
- dura
- subarachnoid space
What is the bottom of the spinal cord called?
conus medularis
What is the name of the ligament that goes from conus medularis to sacrum?
filum terminale
What is the dura mater?
outermost, tough fibrous tube that runs longitudinally from foramen magnum to S2-3
What is CSF supposed to look like?
clear and colorless
What is the function of CSF?
mechanical buffer to protect brain and spinal cord
How much CSF does the body produce per hour?
21 mL/hour or 500 mL/day
How much CSF is in an adult?
150 mL
How much CSF is in the subarachnoid space?
20-35 mL
What is the specific gravity of CSF?
1.003-1.009
What is the order of nerve fiber onset with a spinal?
B C and Adelta Agamma Abeta Aalpha
What are the most common interspaces for dural puncture?
L2-3 or L3-4
What are the two needle approaches?
midline and paramedian
What landmark helps you identify L4?
intercrestal line that runs between the iliac crests
What does hyperbaric mean?
LA solution is heavier than CSF, add glucose to LA
What does isobaric mean?
LA solution is same as CSF, mix LA with CSF
What does hypobaric mean?
LA solution is lighter than CSF, mix LA with sterile water
Where is spinal anesthesia thought to take place?
anterior and posterior nerve roots as they pass through the CSF on their way to the periphery
What is spinal anesthesia?
REVERSIBLE chemical blockade of neuronal transmission produced by the injection of a local anesthetic drug into the CSF contained within the subarachnoid space
What are some advantages of spinal anesthesia?
- ideal technique for procedures involving the lower abd, pelvis/perineum and lower extremities
- anesthetized patient can remain fully conscious or may be sedated
- appropriate choice of agents can provide exceptional postoperative analgesia
- when used with “light general” can be used for upper abd and thoracic cases
- surgical stress reduced by afferent block and can speed patient’s recovery
- reduces risk of venous thrombosis and overall blood loss by reducing arterial and venous pressure
- small dose of local anesthetic required minimizes chance of systemic uptake
Can spinal anesthesia be used for a patient with a full stomach?
yes, but have plan B in case spinal fails
What postoperative complications does spinal anesthesia decrease the incidence of?
nausea/vomiting
sedation
cognitive impairment
wound pain
What is the #1 disadvantage of spinals?
sympathetic blockade that occurs virtually 100% of the time because it is relatively easy to block small autonomic fibers
What are some disadvantages of spinal anesthesia?
- Intense motor blockade that can last longer than the procedure
- post-dural puncture headache
- urinary retention
- “takes too long”
Spinal anesthesia is strongly advocated for with what pathophysiology?
pulmonary disease, although if pulmonary disease is really bad general may allow better gas exchange
What is a common fear of patients undergoing spinal anesthesia?
being “awake,” minimize their fear with your preoperative interview and reassure that pre and intra operative medications will be provided
What type of surgeries/indications would be ideal with spinal anesthesia?
- major intra/abd procedures can be accomplished with high level T4 block
- well managed SAB may be safer for the patient with a full stomach
- urological procedures (TURP)
- obstetrical procedures
- minimal effect on metabolism (safer for liver disease, kidney disease, diabetes)
- reduced systemic blood pressure may reduce risk of venous thrombosis and overall blood loss
What are absolute contraindications to spinals?
- patient refusal
- infection at injection site
- coagulopathy or other bleeding diathesis
- severe hypovolemia
- severe aortic or mitral valve stenosis
- increased ICP
What are relative contraindications to spinals?
- uncooperative patient, psychiatric disease
- septicemia/bacteremia
- preexisting neurological deficit
- chronic backache or headache
- stenotic valvular lesions
- severe spinal deformity
What are controversial issues with deciding whether or not to use spinal anesthesia?
- prior back surgery
- inability to communicate with the patient
- complicated surgical procedures (long duration, major blood loss, respiratory compromise)
If a patient had an allergy to local anesthetics would you still do a spinal?
Yes, but use an amide local anesthetic
What would be some considerations with a spinal in a patient with untreated hypertension?
Could be volume depleted and have severe hypotension after spinal
What is important to remember about getting informed consent for a spinal?
- they should understand the advantages and disadvantages of the procedure
- SAB should be adequate for the procedure but you cannot guarantee it
- indicate risks and potential complications
- indicate the patient appears to understand and accept
- give the patient time to ask questions
- do not attempt to dissuade a patient who has been counseled and agreed to a general anesthetic
- **Documentation does not exonerate you from acts of carelessness or negligence
What premeds/fluids can you give before giving a spinal?
versed for anxiety and amnesia, but do not oversedate the patient
can also adminiser 500-1500 mL of a balanced salt solution to help protect against hypotension
What supportive meds should you have ready when doing a spinal?
- benzo or propofol
- succ
- atropine
- ephedrine or phenyl
What monitors should be on the patient when doing a spinal?
EKG
blood pressure
pulse ox
How is the body of the thoracic vertebrae shaped?
heart shaped
How is the body of the lumbar vertebrae shaped?
kidney-shaped
What is the name of the space between the vertebrae you are trying to identify for needle placement?
laminar foramen
After you insert your needle and it feels “sandy” or “grainy,” what anatomical structure is your needle hitting?
lamina
Which vertebrae has spinous processes that are long and angulated downward?
thoracic vertebrae
Which vertebrae has spinous processes that are blunt and horizontal?
lumbar vertebrae
What is the most important thing that allows you to have a successful spinal?
proper position
What is the arachnoid mater?
middle layer, delicate, nonvascular and ends at S2
What is the pia mater?
- delicate, highly vascular, and covers spinal cord
- subarachnoid space lies between the pia and arachnoid mater (CSF found here)
- holds blood supply that feeds spinal cord
- do NOT want to puncture
Which nerve fiber is responsible for motor and proprioception?
A alpha
Describe the size and myelination for A alpha fibers.
heavy myelination big diameter (6-22 micrometers)
Which nerve fibers are responsible for motor, proprioception, touch and pressure?
A beta
Describe the size and myelination for A beta fibers?
moderate myelination big diameter (6-22 micrometers)
Which nerve fibers are responsible for muscle tone?
A gamma
Describe the myelination and size of A gamma fibers?
moderate myelination and medium sized at 4-6 micrometers
Which nerve fibers are responsible for pain, touch, and cold?
A delta
Describe the myelination and size of A delta fibers?
light myelination and smaller at 1-4 micrometers
Which nerve fibers are responsible for preganglionic sympathetic stimulation?
B fibers
Describe the size and myelination of B fibers.
light myelination and small at 0.5-2 micrometers
Which nerve fibers are responsible for pain, touch, warm, and cold?
C fibers