Flashcards in Spinal Anesthesia Quiz Deck (63):
What are two other names for Spinal Anesthesia?
1. Subarachnoid Block
How many vertebrae in the spinal anatomy?
List the vertebral regions and their associated #s.
What is the High point on the vertebral column while laying supine?
What is the low point on the vertebral column while laying supine?
How many pairs of spinal nerves are there?
The VERTEBRAL COLUMN extends from the?
base of the skull and the foramen of Magnum to the tip of the coccyx
The SPINAL CORD extends from the?
foramen magnum to the L1 in the adult and L3 in the newborn
During spinal anesthesia, what 9 structures does the needle pass through?
4. supraspinous ligament
5. interspinous ligament
6. ligamentum flavum
7. epidural space
8. dura mater
9. arachnoid mater
When utilizing the lateral approach to spinal anesthesia, what two structures do you not pass through?
1. Supraspinous Ligament
2. Interspinous Ligament
The spinal cord is enlarged in what two regions?
1. Cervical Enlargement(C5-T1)-The ventral rami(branches) within this segment form the Brachial Plexus
2. Lumbosacral Enlargement(L2-S3)-contributed corresponding nerves to create the Lumbosacral Plexus
What are the meninges?
non nervous system support tissue that provides a protective covering for the cord and nerve roots from the foramen magnum to the base of the caudal equine.
What are the linings of the meninges and what is their order?
Dura mater(farthermost from the Brain)
Pia mater(closest to the Brain)
What are 3 characteristics of the Subarachnoid space?
-filled with CSF
-contained between Pia and Arachnoid maters
-mater and fluid protect the cord from shock and are the medium for the interaction with LA and opioids
Where does the blood supply to the spinal cord and the nerve roots come from(2)?
1. anterior spinal artery
2. paired posterior spinal arteries
Where is the principal site of action for neuaxial blockade?
What are 3 abnormal curvatures of the spine?
What is Scoliosis?
the most common abnormal curvature and is a lateral curve
What is kyphosis?
excessive posterior curvature or "hump" usually seen in the thoracic region
What is Lordosis?
hollowing of the back, may occur as a result of obesity as the body attempts to restore center of gravity. A temporary Lordosis may occur during pregnancy.
What anatomical level is T4?
Level of the nipples
What anatomical level is T10?
Level of the umbilicus
What anatomical level is T12?
Inguinal or groin region
What is the result of blocking the B-fibers?
venodilation with hypotension; lose preload; 1st nerve blocked bc it is most DISTAL
What is the result of blocking the C and A delta fibers?
loss of pain and temperature; 2nd nerve to be blocked
What is the result of blocking the A-gamma fibers?
loss of muscle tone; 3rd nerve to be blocked
What is the result of blocking the A-beta fibers?
loss of touch and pressure sensation; 4th nerve to be blocked
What is the result of blocking the A-alpha fibers?
loss of MOST motor function and proprioception; larger and more central; 5th nerve to be blocked
*****last and farthest away*****
What is a Differential Block?
Its when a LA interrupts nerve transmission of autonomic nerves but not sensory or motor nerves(because of variation of susceptibility)
In what situations are Differential Blocks seen?
Seen in the more Rostral spinal segments of an intrathecal anesthetic. As the spinal spreads from the epicenter of injection, the distal reaches of drug distribution are presumably of lesser concentrations
Anatomically, what is happening with a Differential Block?
Motor blockade occurs 2-3 segments lower than the sensory block and sympathetic blockade 2-6 segments higher than the sensory block.
***So Cephalad to Caudad***
-Preganglionic Autonomic(B fibers)
Compared with the level of sensory block associated with spinal anesthesia, motor blockade and sympathetic blockade occurs where?
Sympathetic-2 to 6 segments higher than the sensory block
Motor-2 to 3 segments lower than the sensory block
When obtaining informed consent(R/B/A) for a Subarachnoid Block, what are some realistic expectations that should be shared with the patient(8)?
1. inability of obtain adequate anesthesia
5. high or total spinal
7. use of additional sedation
8. allergic reaction
When obtaining informed consent(R/B/A) for a Subarachnoid Block, what are some post complications that may be included that should be shared with the patient(5)?
1. PDPH(post dural puncture headache)
2. transient neurological symptoms
5. peri-dural abscess or hematoma formation
What are 7 potential advantages of a Subarachnoid Block?
1. improved patient satisfaction(especially in elderly)
2. less immunosuppression, compared to GA
3. decreased incidence of N/V
4. a non-general anesthesia option for patients who are hemodynamically unstable or too ill to tolerate GA
5. less post op cognitive impairment, especially in the elderly
6. decrease incidence of PE, ileus and intro blood loss
7. Anesthetic option for those who are susceptible to MH
What are 11 ABSOLUTE contraindications for a Subarachnoid Block?
1. patient refusal
2. increased ICP
3. coagulopathy-know INR
4. skin infection at site
6. pre-existing cord disease
7. operation > duration of action
8. severe Aortic Stenosis(<0.8 cm2)
11. abrupto placenta
What are 11 RELATIVE contraindications for a Subarachnoid Block?
1. major surgery above umbilicus
2. spinal deformity
3. chronic HA or BA-determine BASELINE first
4. blood in CSF that does not clear
5. inability to achieve spinal after 3 attempts
6. pre-existing Neuro deficit
8. uncooperative patient
9. stenotic valve lesion
10. Mobitz I or II
11. 3rd degree block without pacer
What are 3 CONTROVERSIAL contraindications for a Subarachnoid Block?
1. prior back surgery at site of injection
2. inability to communicate with patient
3. complicated surgery:
-major blood loss
-maneuvers that compromise respirations--->belly surgery
What are 2 MAJOR complications of Subarachnoid Blocks?
What is the cause of a Post Dural Puncture Headache?
decrease in amount of available CSF within the Subarachnoid space. This decrease in CSF causes the medulla and brainstem to drop into the Foramen Magnum, stretching the meninges, vessels, and nerves, leading to cephalgia(headache). An additional cause of decreased CSF volume is Cranial Nerve Palsy which leads to decreased blood supply to nerves.
What are the signs/symptoms of PDPH?
1. usually seen several hours to first or second post-op day
2. mild to incapacitating bilateral FRONTAL pain that radiates from behind the eyes toward occiput down into shoulders.
3. Positional, N/V, loss of appetite, blurred vision and photophobia, loss of hearing, vertigo, tinnitus, vertigo and depression
What is the #1 factor affecting incidence of PDPH?
the SIZE of the needle-decreased incidence with smaller needles(33%)
GOAL: create a needle size that minimally rends, tears or cuts dural tissue.
What are 6 treatments for PDPH?
1. horizontal position
2. adequate hydration
3. oral analgesics
4. caffeine 500 mg IV
5. caffeine 300 mg PO(up to 70% relief)
6. Epidural Blood Patch(DEFINITIVE TREATMENT)
What is an Epidural Blood Patch?
Blood clot seals dural rent and increases CSF pressure(90% cure rate first time, >95% cure rate second time, 24 hours after first time)
How is an EBP performed?
The injection of 10-30 ml(USUALLY 20) of aseptically drawn blood into the epidural space to form a close where dural rent is located preventing the further loss of CSF and meningeal traction. Blood is injected until the patient feels "pressure" in the back. Afterwards, bed-rest is prescribed for 1-2 hours.
What 3 types of needles are used with Subarachnoid Blocks and which causes PDPH the most?
1. Gertie Marx Sprotte
3. Quincke(worst to use with PDPH)
What is the INTERCRISTAL LINE?
L3-L4; Superior Iliac Spine and Iliac Crest
What are the 4 approaches to performing a Subarachnoid Block?
1. Classic Midline
4. Taylors Approach
Describe the Classic Midline approach of a SAB.
inserted between spinous processes toward umbilicus
Describe the Lateral approach of a SAB.
a little of classic midline; between Paramedic and Classic Midline
Describe the Paramedian approach of a SAB.
insert 1 cm or 1 fb lateral to the ciudad aspect of the interspace. Then angle medially 10-15 degrees and slightly cephalic(more lateral to lateral approach)
Describe the Taylors Approach to SAB.
(Patrick has never seen this in clinical practice); 1cm ciudad to the PSIS is located, angle needle medially and cephalic 55 degrees toward the 5th lumbar interspace. Best used for pelvic and perineal surgery(more lateral to Paramedic approach. Best used for pelvic and perineal surgeries.
Fun facts of SAB:
1. The accuracy of predicting the precise level of needle insertion is at best 50% without XRAY.
2. In adults, approximately 500ml of CSF produced EACH day.
3. At any given time, you'll find approximately 150mls that flow though the brain and central canal.
4. About HALF of that is in the spinal cord(75 mls in cord only)...RULES of 5's.
What is baracity?
refers to the resting position of 2 fluids with differing SG when fluids are mixed in a single container.
What is Isobaric?
When baracity(the ratio of SG of LA to patient's CSF) = 1. Isobaric spinals require CSF or preservative free NS added. Will stay at 2-4 dermatomal range where you inject. Ex. if you inject at T6, it will go T4, T2 or T8, T10. Stays mostly right where you put it in at.
What is Hyperbaric?
Solutions > 1.0015. Solutions have a SG>CSF. The solution would FALL or SINK to the lowest anatomic point at which CSF is contained within the subarachnoid space in relation to gravity and the patient's position. Affected by GRAVITY, will find most dependent position or structure(spine will be T4)
What is Hypobaric?
drug that is < 0.999; it will FLOAT, Solutions that are LESS dense than CSF; rise or float to the highest ANATOMIC position possible when injected into SUBARACHNOID space. If patient is sitting up right and you inject, it will go straight to the brain or if you stand patient on their it will go straight to their sacrum.
What is specific gravity?
comparison of TWO specific fluids. Has to do with combined weight.
What is the SG of CSF and of water?
What determines the duration of a SAB?
-The duration of the spinal anesthetic is based primarily on the LA and the total dose used. Highly protein bound drugs such as Tetracaine or Marcaine last longer than those that don't, like Lidocaine.
-Vasoconstrictor is done as a EPI WASH. Squirt out all of EPI and 1/10 ml left in EPI vial. Then draw up drug your going to use for your spinal. Has more effect on Tetracaine or Marcaine.
-Can also add opioids(fentanyl, sufenta, morphine)
What are 4 factors influencing LA distribution in CSF?
1. Baracity of Solution
3. Position of the Patient
4. contour of the Spinal Canal
What is Cauda Equine Syndrome(CES)?
-caused by use of HIGHLY CONCENTRATED LA such as 5% LIDOCAINE
-involves DYSFUNCTION OF BOWEL AND BLADDER