Neuraxial Lecture 2 (Exam 1) Flashcards by Jourdan Treece

“controversial” connective tissue that divides the R vs L epidural space

Plica Mediana Dorsalis

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The plica mediana dorsalis is located between what 2 structures

Ligamentum flavum and dura mater space

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What is the problem if the plica mediana dorsalis exists?

Affects medication spread and barrier of medications

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What is a clinical sign that there might be the presence of a plica mediana dorsalis?

Unilateral Blockade

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What 3 things are located in the subarachnoid space?

CSF
Nerve roots
Spinal Cord

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If you advance the needle too far past the subarachnoid space, what could you start to run into before hitting bone?

Pia mater
Spinal cord
Posterior longitudinal ligagament

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How do you know when placing a spinal that you are in the subarachnoid space?

you will hear a “pop” when the needle passes thru the dura mater

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What 2 sensations travel together?

Cold/Heat and Pain travel together

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Epidural dosed LA injected into the subdural space could cause what

High spinal effect (medication affects a larger area than intended)

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Spinal dosed LA injected into the subdural space results in a

Failed spinal block

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The dura mater starts at the _____ and ends at the _______

Foramen magnum and ends at the dural sac

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A very delicate and highly vascular layer of meninges that should never be punctured.

Pia Mater

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It is important to know that LA is reabsorbed in the

Pia Mater

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Where do C1-C7 nerves exit the spine?

C1-C7 nerves exit the spine ABOVE the corresponding vertebrae

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Does C8 spinal nerve exit above or below C7

C8 exits BELOW C7

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How many total pairs of spinal nerves are there?

31 pairs

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How many pairs of spinal nerves does each section have?
C -
T -
L -
S -
Coccyx -

C - 8 pairs
T - 12 pairs
L - 5 pairs
S - 5 pairs
Coccyx - 1 pair

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One nerve is formed by ____ nerve roots

2 nerve roots = 1 nerve (anterior and posterior)

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The ventral nerve root carries (2) types of information from the _______ to the ______

Motor (movement)
Autonomic body processes

Ventral nerve root: from the spinal cord to the body

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The Dorsal nerve root carries ______ information from the ______ to the ______

Sensory info

Dorsal nerve root: from the body back to the spinal cord

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An area of skin that receives sensory nerves from a single spinal nerve root

Dermatome

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Name the dermatome levels: Anterior and inner surface of the lower limbs

L1-L4

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Name the dermatome levels: Foot

L4, L5, S1

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Name the dermatome levels: Medial side of great toe

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Name the dermatome levels: Posterior and outer surfaces of lower limbs

L5, S1, S2

Name the dermatome levels: Lateral margin of foot and little toe

Name the dermatome levels: Perineum

S2-S4

Name the dermatome levels: Umbilicus Level

T10

Name the dermatome levels: Inguinal or groin regions

T12

Name the dermatome levels: Clavicles

Name the dermatome levels: Lateral parts of upper limbs

C5-C7

Name the dermatome levels: Medial sides of the upper limbs

C8 & T1

Name the dermatome levels: Thumb

Name the dermatome levels: Hand

C6-C8

Name the dermatome levels: Ring and little fingers

Name the dermatome levels: Level of nipples

What level do you want to numb for c-section?

The sensory information in the face is not conducted by spinal nerves, it is transmitted through

Trigeminal nerve (CN V)

Branch that handles sensation from the forehead, scalp, and upper eyelids

Ophthalmic Nerve - V1

Responsible for sensory input to the lower eyelids, cheeks, nostrils, upper lip, upper teeth

Maxillary Nerve - V2

Conveys sensations from the lower jaw, lower teeth, lower lip, part of the tongue

Mandibular Nerve - V3

What is the desired dermatome level for perianal/anal surgery ("saddle block")

S2-S5

What is the desired dermatome level for foot/ankle surgery?

What is the desired dermatome level for Thigh/Lower leg/knee surgery?

What is the desired dermatome level for Vaginal delivery/uterine/ hip procedure/ tourniquet/TURP/Knee surgery?

T10

What is the desired dermatome level for Scrotum surgery?

What is the desired dermatome level for penis surgery?

What is the desired dermatome level for Testicular procedure

Testicles are embryonically derived from the same level as the _____ for pain transmission ; Levels: ____

Kidneys; T10-L1

What is the desired dermatome level for urologic/gynecologic/lower abdominal/hysterectomy surgery?

What is the desired dermatome level for C-section/Upper abdominal surgery?

What type of surgery might require concamitant GA due to vagal stimulation from abdominal traction?

C-section/upper abdominal (T4)

During spinal anesthesia, LA acts on the ______ fibers of the spinal nerve roots and inhibits neural transmission in the _______ layers of the spinal cord

Myelinated pre-ganglionic fibers; superficial layers

In epidural anesthesia, the LA diffuses thru the _______ to reach the ______

dural cuff; nerve roots

In epidural anesthesia, the LA can leak thru the _______ into the _______ area

intervertebral foramen into the paravertebral area

What are controllable factors that can affect the spread of medication? (4)

1. Baracity 2. Patient position 3. Dose 4. Site of injection

What are non-controllable factors that affect spread of medication? (3)

1. Volume of CSF 2. Inc. Intra-abdominal pressure (obesity & pregnancy) 3. Age (elderly have less CSF)

What factors do not affect the spread? (5)

1. Barbatoge (repeated aspiration and reinjection of CSF) 2. Speed of injection 3. Orientation of bevel 4. Vasoconstrictors 5. Gender

Is L3-L4 gap larger or L4-L5?

L3-L4 is larger

What is the most reliable factor affecting how far/wide the anesthetic spreads when using a hypo or isobaric solution? (For spinal)

Dose

For hyperbaric solutions: The ____ of the anesthetic to CSF is crucial in determining how it SPREADS

Density

_____ CSF volume correlates with extensive spread of LA in the intrathecal space

Low CSF volume = High spread

In elderly patients, do they have more or less CSF? How does this affect dose?

Neural nerves are more vulnerable to LA and they have decreased CSF volume

What 2 populations have decreased CSF?

Elderly & Pregnancy

What gauge needle do you typically use for spinal? Epidural?

Spinal: 22 gauge Epidural: 18 gauge

In an epidural, which controllable (3) and non-controllable (2) factors have a significant affect on spread?

Controllable: 1. LA volume (most important drug factor) 2. Level of injection (most important procedure factor) 3. Dose Non-cont.: Pregnancy & elderly

In an epidural, what factors (3) have a small affect on spread?

1. LA concentration 2. Patient position (helps increase onset time) 3. Height

What factors in an epidural does not affect spread?

1. Additives 2. Direction of bevel 3. Speed of injection

Additives in the anesthetic might change the onset time or duration of LA but do not change the

Spread

Injection in the Lumbar region spreads: Injection in the Mid-Thoracic region spreads: Injection in the Cervical region spreads:

Lumbar: Spreads cephalad Mid-thoracic: balanced spread cephalad & caudad Cervical: spreads caudad

How heavy is the myelination on: A - alpha A- beta A - gamma A - delta B - Fibers C-Fibers

A - alpha: Heavy A- beta: Heavy A - gamma: Medium A - delta: Medium B - Fibers: Light C-Fibers: None

What are the 2 functions of A-alpha fibers?

Skeletal Muscle - motor Proprioception

What are the 2 functions of A-beta fibers?

Touch & Pressure

What are the function of A-gamma fibers?

Skeletal muscle - tone

What are the 3 functions of A-delta fibers?

Fast pain Temperature Touch

What is the function of B-Fibers?

Preganglionic ANS Fibers

What is the function of Sympathetic C-fibers?

Post-ganglionic ANS Fibers

What is the function of dorsal root C-Fibers?

Slow Pain Temperature Touch

What is the order of onset of block: A - alpha A- beta A - gamma A - delta B - Fibers C-Fibers

1. B-Fibers 2. C-fibers 3. A-delta 4. A-Gamma 5. A-Beta 6. A-alpha

Requires low concentrations of LA, affecting neither sensory or motor neurons, leading to the highest level of blockade

Autonomic blockade

What blocks first?

Sensory, then motor last

Sensory is ___ levels higher than motor; sympathetic is _____ levels higher than sensory

Sensory is 2 levels higher than motor; Sympathetic is 2-6 levels higher than sensory

If sensory block is at T8, where is sympathetic and motor block?

SNS block: T2-T6 Motor block: T8

As a block onsets, what do you lose first?

1. Sympathetic 2. Pain & Temp 3. Motor tone 4. Touch and pressure 5. Loss of motor function & proprioception

As block recovers, what do you start to see first on recovery

Return of: 1. Motor & proprioception 2. Touch and pressure 3. Motor tone 4. Pain and temperature 5. Sympathetic

First to lose and last to return?

Sympathetic

Last to block and first to return?

Motor & Proprioception

What is the first SENSE to be blocked? Second sense to be blocked? Last sense to be blocked?

Temperature Pain Light touch or pressure

The modified Bromage Scale specifically evaluates the function of the _______ nerves

Lumbosacral nerves

Bromage scale score: No motor block

Bromage scale score: Slight motor block; Patient cannot raise an extended leg but can still move the knees and feet

Bromage scale score: Moderate motor block; the patient cannoto raise an exxxtended leg or move the knee but can move feet

Bromage scale score: Complete motor block

CV affects of neuraxial anesthesia: Preload, Afterload, CO, HR

Decrease ALL

In healthy patients, SVR can decrease by _____% Elderly or cardiac patients, SVR can decrease by ___%

Healthy: 15% Elderly/CV: 25%

Initially, CO might ____ and then ____ over time due to changes in blood vessel dilation speed

increase; decrease over time

blockade of cardiac accelerator fibers reduces ______ tone leading to bradycardia

SNS tone

Response to ventricular under-filling mediated by the 5-HT3 receptors in the vagus nerve and ventricular myocardium that causes bradycardia & asystole

Bezold-Jarisch Reflex

What drug antagonizes the Bezold-Jarisch Reflex?

Ondansetron

Triggered by reduced stretching in the heart's right atrium causing bradycardia?

Reverse Bainbridge Reflex

Caused by unopposed PNS tone to the cardio-accelerator fibers that results in profound bradycardia, hypotention: seen in young adults with high PNS tone ________ spinals ________ epidurals Happens _____ min after spinal onset

Sudden cardiac arrest 7:10,000 spinals 1:10,000 epidurals 20-60 min after spinal onset

Sudden cardiac arrest after spinal is associated with (2)

1. Large blood loss 2. Orthopedic cement placement

What drugs/Meds (3) and intervention (1) can prevent spinal-induced hypotension?

1. Vasopressors 2. 5-HT3 Antagonists 3. Fluid Management 4. Positioning

How should you fluid manage someone to prevent hypoptension?

Co-load 15 mL/kg right after blockade avoid pre-loading & excess fluids

What type of positioning prevents hypotension?

Slight pelvic tilting optimizes blood flow and reduces risks

Failure to treat/delay of tx for hypotension increases ____

mortality

If your patient has symptomatic bradycardia, which vasopressor (epinephrine or ephedrine) is preferred?

Ephedrine

What drug class can be used if a patient is experiencing bradycardia?

Anticholinergics (Atropine, glycopyrrolate)

Trendelenburg can help with hypotension, but > ___ degree tilt reduces cerebral perfusion by decreasing brain drainage

> 20 degree tilt decreases CPP

If the block is not set yet, the block height can increase due to ______

Gravity

Even with high (T4) level spread, pulmonary effects are minimal and only the _____ & _____ decreases

ERV and small dec. in Vital capacity due to loss of abdominal muscle contribution in forced expiration

High thoracic block can block the _____ muscles of respiration (2)

Accessory 1. Intercostal 2. Abdominal

Another word for morbidly obese

Pickwickian syndrome

Feelings of ______ in normal population is extremely common due to loss of sensory feedback from the chest. Pt. might lose ability to take big breaths and strong coughs

dyspnea

Although rare, high cx of LA in the CSF can reduce blood flow to the brain-stem causing

Apnea

PNS innervation in the GI tract is via the _____ nerve which originates in the medulla

Vagus Nerve

_____ portion of PNS nerves transmit satiety, distention & nausea

Afferent PNS

_____ portion of PNS nerves produce tonic contractions, sphincter relaxation, peristalsis, secretion

Efferent PNS

SNS innervation of the GI tract stems from _____ levels

T5-L2 levels

______ portion of SNS transmits visceral pain

SNS Afferent

_______ portion of SNS transmits peristalsis, gastric secretion & causes sphincter contraction/vasoconstriction

SNS Efferent

Esophagus innervation is from levels: _____

T4-T5

Neuraxial anesthesia ____ SNS tone and ____PNS activity

decreases SNS tone Increases PNS activity

Unopposed vagal tone in the GI system causes: -Relaxed sphincter -_____ peristalsis -Small, contracted gut with active paralysis -____ GI blood flow -NV in ___% of patients -______ postop ileus in abdominal surgery

Increases peristalsis Increases GI blood flow 20% NV Decreases Post-op ileus

If MAP is unchanged, does neuraxial anesthesia change the renal blood flow?

SNS blockade above ____ affects bladder control causing the urinary sphincter tone to relax

T10

The addition of neuraxial opioids has 2 effects on the GU system

1. Decreases detrusor contraction (sensation that we need to pee) 2. Increase bladder capacitance

Pain, tissue trauma and inflammation due to activation of somatic and visceral afferent fibers during surgery causes: Elevated cortisol, epinephrine, norepinephrine, vasopressin, and RAAS activation. ______ can partially suppress or totally block neuroendocrine response

Neuraxial blockade can partially suppress the response in major invasive surgery and totally block the response in LE surgery

Maximum neuroendocrine blockade benefits occur if the neuraxial block occurs ______ the surgical stimulus

BEFORE

What part on the organic LA structure decides: drug class, metabolism, and allergic potential?

Intermediate chain

Cocaine is an ESTER - and it is unique because it is metabolismed by:

Pseudocholinesterase and CYP 450 (Liver)

Allergies are more common with _____ LA due to the _______

Esters; Para-aminobenzoic Acid (PABA)

Is there cross sensitivity in the esters? What does this mean

Yes - if a patient is allergic to one ester drug, avoid ALL ester drugs

The preservative in amides is ______ and allergic reaction is _____

Methylparaben; Rare

Is there cross-sensitivity between ester and amide?

What determines onset of action?

pKA (except chloroprocaine which has a fast onset d/t its high concentration)

What determines potency?

Lipid solubility

What drug property determines duration of action?

Protein binding (a1-acid glycoprotein)

What form of the drug actually blocks the Na+ channel from. the inside of the cell?

Ionized form

Factors that affect vascular uptake and plasma concentration of LA (5)

1. Site 2. Blood flow to tissue 3. Physiochemical properties (pkA, Protein binding) 4. Metabolism 5. Vasoconstrictor

Highest to lowest blood concentrations based on site

IV Tracheal Intercostal Caudal Paracervical Epidural Brachial Sciatic SubQ

Neuraxial Lecture 2 (Exam 1) Flashcards

(141 cards)