EPIDURAL ANESTHESIA Flashcards
Risk factor for cauda equina usually with undiagnosed?
Undiagnosed spinal stenosis (detected during
evaluation of the new neurologic deficits) was a risk factor for cauda equina syndrome
Cutaneous Landmarks : Fifth finger
Segmental level is ____
significance________
Fifth finger
C8
All cardioaccelerator fibers (T1-T4) blocked
Cutaneous Landmarks : Nipple line
Segmental level is ____
Type of operation_______
Significance______
T4-T5
Upper abdominal
Possibility of cardio-accelerator blockade
T4-T5 is at the
nipple line
Cutaneous Landmarks : Tip of xiphoid
Segmental level is ____
Type of operation_______
Significance_____
T6
Lower Abdominal
Splanchnics (T5-L1) blocked
Cutaneous Landmarks : Umbilicus
Segmental level is ________
Type of operation_______
Significance________
T10
Hip
Sympathetic blockade to lower extremities
Cutaneous Landmarks : Lateral aspect of foot
Segmental level is ________
Type of operation_______
Significance________
S1
Leg and foot
No lumbar sympathectomy
Cutaneous Landmarks : Lateral aspect of foot
Segmental level is ________
Type of operation_______
Significance________
Perineum S2-S4 Hemorrhoidectomy
Termination of the spinal cord in adult is
L1
The dural sac terminates at
S2
When is paramedian approach recommended for Epidural anesthesia?
When at the THORACIC level T1 - T7 to bypass ANGLED spinous process
At levels below T7_________
Needle insertion becomes similar to L2-L3
Lumbar Spine The epidural space is________
widest, i.e., 5-6 mm.
Lumbar Spine Needle insertion below
L1 (in adults) avoids the spinal cord.
Lumbar Spine The ligamentum flavum is
thickest in the midline in the lumbar area.
Lumbar Spine: The spinous processes
have only slight downward angulation.
Lumbar Spine The epidural veins are
prominent in the lateral portion of the epidural space.
Thoracic Spine
The epidural space is__________
3-5 mm in the midline, narrow laterally.
Thoracic Spine The ligamentum flavum is
thick but less so than in the midlumbar region.
Thoracic Spine The spinous processes have
extreme downward angulation; the paramedian
approach is recommended.
Cervical Spine
The epidural space is_______
The ligamentum flavum is_____
The spinous process at C7 is
narrow, only 2 mm at C3-6
thin.
almost horizontal.
Vertebra prominens level
C7
Root of scapular spine level
T3
Inferior angle of scapula level
T7
Intercristal line level
L3, 4
Posterior superior iliac spine
S2
The major sites of action of epidurally injected local anesthetics are
The spinal nerve roots, where the dura is relatively thin.
How does the addition of vasoconstriction help local anesthetics?
The addition of vasoconstricting agents reduces blood flow in the richly vascularized epidural space, reducing systemic absorption; because more of the drug remains in Close to the nerve, the onset of block is quicker and the duration of action is longer.
Complications of Epidural
Spinal hematomas, Cauda Equina, meningitis, epidural abscess.
Local anesthetic dose may be calculated by the following formula:
dose equals 1 to 1.5 mL of local anesthetic agent per segment blocked
When Epidural start regressing
A second dose of approximately 50% of the initial dose will maintain the original level of anesthesia if injected when the blockade has regressed 1 or 2 dermatomes
How to give a 2nd dose?
A second dose of approximately 50% of the initial dose will maintain the original level of anesthesia if injected when the blockade has regressed 1 or 2 dermatomes
The addition of epinephrine can prolong the duration of lidocaine nerve block by
up to 50%.
Epidural Space
The epidural space may be approached using a_____or _______insertion.
midline or a paramedian needle
How do you identify the EPIDURAL SPACE?
The epidural space is identified by the passage of the
needle from an area of high resistance (ligamentum flavum) to an area of low resistance (epidural space).
After the needle is positioned in the ligamentum flavum,
a syringe with a freely movable plunger is attached, and continuous pressure is applied to the plunger.
If the needle is positioned correctly in the ligament,
the syringe
should not inject when pressure is applied to the plunger.
As the needle passes into the epidural space,
a sudden loss of resistance in the plunger will be felt, and the air or fluid will easily inject. At this point, a flexible
nylon catheter may be advanced 3 to 4 cm through the needle into the epidural space to allow repeated and incremental injections.
Accurately identify the level of the vertebrae as well as to estimate the depth of the epidural space
Pre-insertion ultrasound imaging has been demonstrated
A test dose of is then injected, An
3 mL of local anesthetic solution (typically lidocaine,
1.5%) containing 1:200,000 epinephrine and the patient is
observed for signs of intravascular, subdural, or subarachnoid injection.
After the test dose inserted How do you assess intravascular, subdural or subarachnoid?
increase in systolic blood pressure of at least 15 mm Hg or an increase in heart rate of at least 10 beats/min represents intravascular injection, whereas a change in lower extremity sensation (with or without a decrease
in blood pressure) denotes subdural or subarachnoid injection.
Extreme upward angulation required for
Midthoracic region
What is the widest part of the epidural space?
L2 is thought to be the widest part of the epidural space, measuring 5 to 6 mm at this level.
The spinal cord begins at the level of the foramen
magnum and ends below as the conus medullaris.
At birth, the cord extends to
L3, but it moves to its adult position at the lower border of L1 by age 1 year.
The spinal meninges are three individual membranes that surround the spinal cord
Dura, Arachnoid, Pia
The dura is a ______layer
Tough
THin and AVASCULAR
ARACHNOID
MIddle membrane closely attached to the dura
Arachnoid
Thin Layer and HIGHLY VASCULAR
PIA
The space between the arachnoid and pia is the
subarachnoid space.
Meninges layer from outer to inner
Dura, Arachnoid, Pia
From closer to spinal cord to out
Pia - Arachnoid - Dura
SIFED-ASP order of ligaments
Supraspinal -> Interspinal –> Flavum , ligamentum –> Epidural -> Dura –> Arachnoid –> Subarachnoid –> Pia
The strongest of the ligaments
The ligamentum flavum,
Blood Supply
The spinal cord is supplied by Throughout their length,
one anterior spinal artery and two posterior
spinal arteries.
Blood Supply
The three spinal arteries receive contributions from
radicular branches of intercostal arteries.
The most caudal medullary artery is usually ______
the largest, the arteria medullaris magna anterior (artery of Adamkiewicz).
The MEDULLARY MAGNA ANTERIOR (artery of Adamkiewicz) artery has a variable origin along the spinal cord, arising
in__________15% of patients,
in _________60%, and
in _________ 25%.
between T5 and T8
between T9 and T12
between L1 and L5
Primary ligaments that provide vertebral column stability by binding the vertebral bodies.
The anterior and posterior longitudinal ligaments
