Term
| What are the 3 functional units of synthetic local anesthetics? |
|
Definition
1. tertiary amine (hydrophilic)
2. aromatic ring (lipophilic)
3. these 2 are joined by either an ester or amide linkage |
|
|
Term
| Which type of LA's are more prone to cause allergic reactions? Are they common? What causes the allergic reaction? |
|
Definition
| Esters; still very uncommon; caused by metabolic product-- PABA |
|
|
Term
| How are amides and esters metabolized? |
|
Definition
Esters- pseudocholinesterase
Amides- Liver |
|
|
Term
| LA's are commercially prepared as __________. Are they acidic or basic in solution? |
|
Definition
| Hydrochloride salts; acidic |
|
|
Term
| Why must you not give anything with preservatives during neuraxial technique? |
|
Definition
| The preservatives are neurotoxic |
|
|
Term
| What is NaHCO3 presumed to do to onset time of LA? |
|
Definition
|
|
Term
| _________ are integral membrane proteins that initiate and propagate action potentials. |
|
Definition
|
|
Term
| What is the specific receptor for LA binding? |
|
Definition
| Alpha subunit of Na-channel |
|
|
Term
| LA's gain access to the Na channel in the ___________ state, however they bind when the Na channel is in the ___________ state. |
|
Definition
| open-activated; closed-inactivated |
|
|
Term
| T/F. LA's cross the membrane in the noin-ionized form, but bind to the Na channel in the ionized form |
|
Definition
|
|
Term
A) potency of LA is directly related to _______.
B) Duration of action is directly related to __________ (primarily) and ___________ (secondarily). |
|
Definition
A) lipid solubility
B) protein binding; lipid solubility |
|
|
Term
| T/F. Speed of onset is directly proportional to pKa. |
|
Definition
| FALSE. It is INDIRECTLY proportional to pKa |
|
|
Term
| What is necessary in order for LA to block a myelinated fiber? |
|
Definition
| It must generally inhibit 3 successive nodes of Ranvier |
|
|
Term
What is blocked faster:
A) myelinated or unmyelinated?
B) frequently firing nerves or seldom-firing nerves?
C) small unmyelinated or large unmyelinated? |
|
Definition
A) Myelinated
B) Frequently firing nerve
C) small unmyelinated nerve |
|
|
Term
| What is frequency dependent blockade (Use-Dependence)? |
|
Definition
| Nerves that have frequent action potentials are easier to block because they are in the states necessary for the drug to enter the Na channel and bind. Nerves that don't "fire" often are in the resting state often and the LA can't bind to the channel |
|
|
Term
| What are the types of nerve fibers? |
|
Definition
| A fibers (A-alpha, A-beta, A-gamma, and A-delta), B fibers, and C fibers |
|
|
Term
|
Definition
Motor efferent conduction:
A-alpha: innervate skeletal muscle; motor/proprioception
A-beta: sensations of touch/pressure
A-gamma: skeletal muscles for muscle tone
A-delta: sensations of pain (1st pain- FAST), temp., touch |
|
|
Term
T/F. A fibers are ALL myelinated
T/F. C fibers are ALL unmyelinated |
|
Definition
|
|
Term
|
Definition
| preganglionic autonomic nerve fibers-- they are all myelinated and frequently firing |
|
|
Term
|
Definition
UNMYELINATED
Pain (slow) aka "second pain", reflex responses, POST-ganglionic autonomic |
|
|
Term
| Out of all the A, B, and C fibers, what is the order of blockade and recovery? |
|
Definition
Order of blockade:
B-fibers (sympathetic), then A-delta and C fibers at the same time, then A-gamma, A-beta, and lastly A-alpha.
Recovery is in the opposite direction starting with A-alpha fibers and ending with B-fibers |
|
|
Term
| What effect does epinephrine have as an adjuvant to local anesthetics? |
|
Definition
1. decreases blood flow to area which decreases uptake of LA and prolongs duration of effect
2. enhances the block because allows for greater concentration of LA exposure to nerve fibers
3. Exerts pre-synaptic alpha-2 adrenoreceptor activity that contributes to analgesia |
|
|
Term
| What is the role of clonidine as an adjuvant to local anesthetics? |
|
Definition
used for central blocks
works similar to epinephrine in that it binds to pre-synaptic alpha-2 adrenoreceptors of primary afferent fibers and several brainstem nuclei
Has also been shown to increase ACh and Norepi in CSF and inhibits release of neurotransmitters responsible for nociception such as substance P |
|
|
Term
T/F. Absorption of locals at specific sites is determined by tissue blood flow.
What routes have the fastest absorption of LA d/t tissue blood flow? rank from fastest to slowest. |
|
Definition
TRUE.
IV, intercostal, tracheal, caudal/paracervical, epidural, brachial plexus, spinal, subQ |
|
|
Term
| What is the name of the active metabolite of lidocaine? |
|
Definition
|
|
Term
| What is the name of the metabolite for prilocaine? What is it's significance? |
|
Definition
| Ortho-toluidine. It converts hemoglobin to methemoglobin (Fe2+ to Fe3+) |
|
|
Term
| T/F. S&S of CNS toxicity is due to concentration of drug in epidural or subarachnoid space. |
|
Definition
| FALSE. It is due to concentration in the blood! |
|
|
Term
| What is the treatment for LA toxicity? |
|
Definition
| Minor reactions may be allowed to spontaneously terminate Maitain patent airway administer O2 and barb/benzo/propofol to raise seizure threshold supportive therapy for CV system with fluids, pressors Amiodarone and vasopressin instead of epinephrine and lidocaine **20% intralipids 1.5 mL/kg bolus then infusion at 0.25 mL/kg/min for 30-60 mins. |
|
|
Term
| T/F. Acidosis raises seizure threshold. |
|
Definition
| FALSE. It lowers seizure threshold |
|
|
Term
| What is the mechanism by which intralipids treats LA toxicity |
|
Definition
| It gives the LA somewhere else to bind |
|
|
Term
| Where is pseudocholinesterase produced? |
|
Definition
|
|
Term
| What does dibucaine number represent? |
|
Definition
| The amount (%) of NORMAL pseudocholinesterase inhibited by dibucaine |
|
|
Term
| What are the normal and abnormal dibucaine numbers we should be concerned with as anesthetists? |
|
Definition
80= homozygous TYPICAL- normal
40-79= heterozygous atypical; block prolonged by ~20-30 mins.
20-39= homozygous atypical; block can last up to 8 hrs. pt goes to PACU intubated |
|
|
Term
| how many paired spinal nerves are there? |
|
Definition
| 31- 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal |
|
|
Term
| When supine, what are the highest and lowest points in the spinal column? |
|
Definition
highest= L3-L5
Lowest= T5-T6 |
|
|
Term
| how long is the vertebral column and spinal cord? |
|
Definition
| 26-27 inches; 17-18 inches |
|
|
Term
| list the bony structures of the vertabral column. |
|
Definition
C1=atlas. lacks body, attaches to skull
C2=axis. felt just below occipital protuberance
C7= cervicothoracic junction (most prominent midline structure at base of neck)
Thoracic vertebrae I.D. by corresponding ribs
Line drawn b/w lower borders of scapula crosses the vertebral axis @ ~T7
Line drawn b/w iliac crests represents L4-L5 |
|
|
Term
| where does the epidural space start (cephalad) and end (caudal)? |
|
Definition
| starts at the foramen magnum and ends at the sacrococcygeal membrane of the sacral hiatus |
|
|
Term
| The dura mater ends @ _____ and fuses with the __________. |
|
Definition
|
|
Term
| Where do the meninges end? |
|
Definition
Dura and archnoid mater end at S2
Pia mater ends at filum terminale |
|
|
Term
| T/F. The arachnoid and pia mater are highly vascular. |
|
Definition
| FALSE. The pia mater is, but the arachnoid mater is non-vascular |
|
|
Term
| What is the difference b/w thoracic vertebrae and lumbar vertebrae in relation to how you must point your needle for central block? |
|
Definition
| The spinous processes in lumbar vertebrae are relatively horizontal so you point the needle perpindicular to the skin. In the thoracic vertebrae the spinous processes point downward necessitating a cephalad angle of the needle for insertion. |
|
|
Term
| **Where does the spinal cord extend to? |
|
Definition
| From foramen magnum to L3 in newborn and L1 in adult |
|
|
Term
| Lumbar puncture is usually performed below what vertebrae? |
|
Definition
| L2 (L2-L3 interspace and below) |
|
|
Term
| **BLOOD SUPPLY TO SPINAL CORD |
|
Definition
2 posterior spinal arteries: supply posterior (sensory) portion of cord and receive supply from cerebral system and many collaterals.
1 anterior spinal artery: supplies anterolateral cord. Gets blood from radicular arteries that branch from aorta (poor collaterals).
Artery of Adamkiewicz (arteria radicularis magna):segmental branch off aorta that supplies thoracolumbar region. It is unilateral and most often occurs near T8-T12 on the left side |
|
|
Term
| What is the significance of the poor collaterals that the anterior spinal artery receives? |
|
Definition
| If there is injury to radicular arteries (especially artery of Adamkiewicz) there is a major risk of ischemia to a large portion of the spinal cord |
|
|
Term
| What are the indications for spinal anesthesia? |
|
Definition
| Procedures involving lower extremities, hip, perineum, lower abdomen, lumbar spine, rectal surgery, and obstetrics |
|
|
Term
| Would spinal anesthesia be a good choice for someone getting surgery in the upper abdomen such as cholecystectomy or gastric rsx? |
|
Definition
| No because you would need a high level block and the risks would outweigh the benefits. Just do GETA |
|
|
Term
| What are the NYSORA guidelines for stopping anticoagulation before neuraxial anesthesia? |
|
Definition
> NSAIDS and ASA are NOT contraindicated
> LMWH: hold 12 hr. before insertion and 2 hrs after catheter removal
> GPIIa/IIIb inhibitors: held for 4 wks post epidural
> clopidogrel: stop 7 days before
> ticlopidine: stop 14 days before |
|
|
Term
| What is the first ligament encountered with the paramedian approach? |
|
Definition
| Ligamentum flavum (the supraspinous and interspinous ligaments are bypassed) |
|
|
Term
| Why use the paramedian approach for neuraxial anesthesia? |
|
Definition
| If the patient has a calcified interspinous ligament, difficulty flexing spine, or abnormal curvature of spine |
|
|
Term
| **What is the specific gracity of CSF? Why is this important? |
|
Definition
1.003-1.008
It is important because that is the frame of reference for baracity. If the agent is heavier than CSF (hyperbaric) the spec. gravity will be higher than 1.008 and the solution will "drop" with gravity. The opposite is true for hypobaric. Isobaric solutions stay close to site of injection |
|
|
Term
| T/F. Hyperbaric solutions are most commonly used and they are achieved by a mixture of LA with sterile water. |
|
Definition
| FALSE. They are the most commonly used but mixed with dextrose |
|
|
Term
| What is a simple technique to protect (somewhat) against cephalad spread to cervical level? |
|
Definition
| Neck flexion with a pillow or folded blanket under occiput |
|
|
Term
| mixing LA with CSF causes a _______ solution. |
|
Definition
|
|
Term
| **In the supine patient receiving a spinal, what governs spread of the agent after injection? |
|
Definition
| curve of spine. hyperbaric solution will settle to low point of spine (T5) hypobaric solution will go to high point (L3) |
|
|
Term
| **How does pregnancy affect the spread of local anesthetic for epidural/spinal? |
|
Definition
| Uterus causes inc. intra-abdominal pressure and increased volume in the epidural venous plexus. This results in smaller and tighter epidural and subarachnoid spaces and a HIGHER SPREAD |
|
|
Term
| **T/F. Arterial AND venous dilation occur to produce hypotension during neuraxial anesthesia. |
|
Definition
| TRUE. However, venodilation is a much greater contributor to hypotension |
|
|
Term
| What are cardiac accelerator fibers? What is their relevance to neuraxial anesthesia? |
|
Definition
| They are sympathetic efferent fibers that arise at T1-T4. When stimulated they increase HR and when blocked (as in high spinal) they cause unopposed vagal activity that leads to profound bradycardia |
|
|
Term
| **T/F. Blockage of intercostal muscles for most people is not enough to affect tidal volume. |
|
Definition
|
|
Term
| **T/F. You have to be very careful during neuraxial anesthesia because blockade up to T2 will cause blockade of phrenic nerve and paralysis of diaphragm. |
|
Definition
| FALSE. Phrenic block is seen with block up to C3-C5. It is RARE. |
|
|
Term
| **T/F. Apnea during high spinal is usually the result of blockade of phrenic nerve with resultant diaphragmatic paralysis. |
|
Definition
| FALSE. Apnea during spinal is due to hypoperfusion to brainstem respiratory centers. |
|
|
Term
| Urinary retention is common during neuraxial anesthesia because muscle tone in bladder is eliminated and blockage of _____ is often last to resolve |
|
Definition
|
|
Term
| What causes N/V during neuraxial anesthesia? |
|
Definition
| unopposed parasympathetic activity leading to hypermotiliy and Hypotension |
|
|
Term
| post dural puncture headache (PDPH) |
|
Definition
| Severe headache caused by puncture of dura during spinal or epidural anesthetic (more common with spinal). CSF leaks which decreases CSF pressure. This causes increase in CBF and downward traction on nerve roots when patient sits/stand up |
|
|
Term
| **What is the most important factor causing PDPH? |
|
Definition
|
|
Term
| T/F. PDPH occurs more in thin people than fat people and more in females than males |
|
Definition
|
|
Term
| **Why does caffeine relieve PDPH? |
|
Definition
| It increases production of CSF (major reason). It also causes cerebral vasoconstriction leading to dec. CBF |
|
|
Term
| Explain the process of epidural blood patch |
|
Definition
placement of NEW IV (usually in AC).
Placement of epidural needle AT AREA OF LUMBAR PUNCTURE.
12-20 mL of patients blood is drawn from NEW IV WITH STERILE TECHNIQUE! and it is injected into epidural space
> stop injecting blood if patient c/o pain/discomfort or have reached 20 mL max |
|
|
Term
| **Any spinal anesthetic that does not resolve within a reasonable amt of time or suddenly progresses after initial effects have worn off should be investigated immediately... Why? |
|
Definition
| Could be due to epidural hematoma from bleeding of epidural venous plexus. Early diagnosis is key (CT or MRI). If present pt will need emergent decompressive laminectomy |
|
|
Term
| Where is the widest point of the epidural space? |
|
Definition
| L2 (contains epidural venous plexus aka Batson's plexus) |
|
|
Term
| Which nerves are the most difficult to block during epidural? |
|
Definition
| L5 and S1 (they are large). They take time to block |
|
|
Term
| T/F. Onset of epidural is faster than spinal |
|
Definition
| FALSE. It is slower because it takes time for drug to diffuse across membranes to spinal nerves |
|
|
Term
| DO NOT EVER PULL THE EPIDURAL CATHETER BACK THROUGH THE TUOHY NEEDLE BECAUSE YOU CAN SHEAR OFF THE TIP OF THE CATHETER |
|
Definition
|
|
Term
| Hanging drop method not used much anymore, but if it is used what type of epidural will it most likely be? |
|
Definition
| Thoracic (negative pressure) |
|
|
Term
| T/F. During spinal anesthesia a simple dosing rule of thumb is to use 1-2 mL of LA for each spinal segment to be anesthetized. |
|
Definition
FALSE> That is for epidurals!
Inject 5mL every 3-5 mins. until desired effect and ALWAYS aspirate first |
|
|
Term
| What nerve root fibers do neuraxial opioids modulate in the spinal cord? |
|
Definition
|
|
Term
| What is the most common regional technique used in peds? |
|
Definition
|
|
Term
| What types of blocks affect the brachial plexus? |
|
Definition
| interscalene, supraclavicular, infraclavicular, and axillary blocks |
|
|
Term
| The brachial plexus is formed by the union of what nerves? |
|
Definition
|
|
Term
A) What forms the superior trunk?
B) What forms the middle trunk?
C) what forms the inferior trunk? |
|
Definition
|
|
Term
A) The trunks of the brachial plexus each break off into ___________.
B) What forms the lateral cord?
C) What forms the posterior cord?
D) What forms the medial cord? |
|
Definition
A) anterior and posterior divisions
B) anterior divisions from the superior and middle trunk
C) posterior divisions from all 3 trunks
D) extension of anterior division of inferior trunk |
|
|
Term
| Lateral cord gives off __________ and terminates as the ___________. |
|
Definition
| lateral branch of median nerve; musculocutaneous nerve |
|
|
Term
| the posterior cord gives off the _________ and terminates as the _________. |
|
Definition
| axillary nerve; radial nerve |
|
|
Term
| the medial cord gives off the ___________ and terminates as the ___________. |
|
Definition
| medial branch of median nerve; ulnar nerve |
|
|
Term
|
Definition
> most proximal approach to brachial plexus
> good for upper arm and shoulder procedures
> not good for hand surgery b/c C8-T1 hard to block from this approach |
|
|
Term
| **What is the most common complication of interscalene block? |
|
Definition
| Stellate ganglion block resulting in Horner's syndrome: ptosis, miosis (d/t sympathetic block), anhidrosis (dec. sweating on affected side of face), nasal stuffiness, and enopthalmos (eyes sunken in) |
|
|
Term
|
Definition
> plexus very compacted in this region so achieves excellent block to entire arm AND hand
> pneumothorax most common with this type of brachial plexus blocks |
|
|
Term
| What complications are associated with infraclavicular blocks? |
|
Definition
| pneomothorax, hemothorax, chylothorax (lymph), nerve injury, and hematoma |
|
|
Term
| What type of brachial plexus block is preferred for outpatient procedures? |
|
Definition
|
|
Term
| **KNOW slide 27 of upper ext block lecture and pg 335 in M&M** |
|
Definition
|
|
Term
| **What is the biggest complication of axillary block? |
|
Definition
| inadequate anesthesia of the musculocutaneous nerve |
|
|
Term
| **interscalene block most often misses what nerve in the brachial plexus? |
|
Definition
|
|
Term
| **Name the extraocular muscles of the eye |
|
Definition
4 rectus muscles (medial, later, superior, and inferior)
2 oblique muscles (superior and inferior) |
|
|
Term
| **What is the retrobulbar cone? |
|
Definition
| cone formed by the 4 rectus muscles |
|
|
Term
| what is normal intraocular pressure? |
|
Definition
|
|
Term
| T/F. Glaucoma impairs blood flow to optic nerve |
|
Definition
|
|
Term
| What is the major difference b/w retrobulbar and peribulbar block? |
|
Definition
| retrobulbar you inject INSIDE the cone and peripulbar you inject OUTSIDE the cone |
|
|
Term
| T/F. You need to use more volume of local anesthetic for retrobulbar block |
|
Definition
| FALSE. Need more for peribulbar b/c not injecting inside cone |
|
|
Term
| **what are the complications of retrobulbar block? |
|
Definition
>Oculocardiac reflex (five and dime reflex): bradycardia, sinus arrest, VF. consists of trigeminal (V) Afferent pathway and vagal (X) Efferent pathway.
> Retrobulbar hemmorhage-- exopthalmos
> puncture of globe
>**intra-arterial injection: patient will seize IMMEDIATELY
>**Optic nerve sheath injection: seizure, hypotension, resp. arrest 3-7 MINS AFTER BLOCK
> direct optic nerve trauma
> injury to extraocular muscles |
|
|
Term
| **What is the main cause of oculocardiac reflex? |
|
Definition
| Pressure on the globe and traction on medial rectus muscle. Tell surgeon to STOP stimulation of the eye |
|
|
Term
| What nerves roots make up the lumbar plexus? |
|
Definition
|
|
Term
| L2-L4 segments break off from lumbar plexus to form what nerves? What area is innervated by these branches? |
|
Definition
| Lateral femoral cutaneous, obturator, and femoral nerves; Innervate the anterior thigh |
|
|
Term
What nerve segments form the sciatic nerve?
What does the sciatic nerve innervate? |
|
Definition
L4,L5, S1-S3
Innervates (motor and sensory) the posterior aspect of entire leg and foot |
|
|
Term
| The sciatic nerve divides to form what two nerves? |
|
Definition
| The tibial and common peroneal nerves |
|
|
Term
| What areas of the leg does the femoral nerve innervate? |
|
Definition
| anterior thigh, knee, and medial foot |
|
|
Term
What part of leg does each section innervate (sensory):
a. femoral
b. obturator
c. sciatic
d. tibial
e. lateral femoral cutaneous
f. common peroneal
g. saphenous |
|
Definition
a. anterior thigh, knee, and medial foot
b. small area behind knee
c. posterior aspect of entire leg and foot
d. plantar surface of foot
e. anterolateral thigh
f. dorsal and lateral foot
g. anteromedial foot |
|
|
Term
| The ________ is a terminal branch of the femoral nerve and is the only innervation to the foot that is not part of the sciatic system. |
|
Definition
|
|
Term
| **In order to block the entire foot at the level of the ankle how many nerves need to be blocked? What are they? |
|
Definition
5;
3 superficial: saphenous (femoral), sural (tibial), and superficial peroneal (common peroneal)
2 Deep nerves: Posterior tibial (tibial) and deep peroneal (common peroneal) |
|
|
Term
Name innervation of following nerves:
a. saphenous
b. sural
c. sup. peroneal
d. posterior tibial
e. deep peroneal |
|
Definition
a. anteromedial foot
b. lateral foot
c. dorsal foot and all five toes
d. heel, medial and part of lateral sole of foot
e. medial half of dorsal foot especially first and second toes
e. |
|
|
Term
| **know slide 29 lower extremity blocks lecture** |
|
Definition
|
|
