Exam 1 Spinal & Epidural Neuraxial Anesthesia [6/03/24] Flashcards
What is the preservative found in Amide LA’s?
Methylparaben
True or False:
If someone has an ester allergy, they will most likely have an amide allergy?
False
There is no cross-sensitivity between esters and amides.
What two components of a LA determine its onset of action?
- pKa
- Concentration
What component of a LA determines its potency?
Lipid solubility
The protein binding % of a LA determines its ___.
Duration of Action
Factors Influencing Vascular Uptake and Plasma Concentration of Local Anesthetics include:
STAMP
Site of Injection
Tissue Blood Flow
Addition of Vasoconstrictor
Metabolism
Physiochemical Properties
Which LA do we NOT want to use in a Bier Block?
Bupivicaine
Which type of LA baracity is good for Hip Replacements per Dr. Tubog?
Isobaric
List examples of Hyperbaric LA solutions:
Bupivicaine 0.75% in 8.25% Dextrose
Lidocaine 5% in 7.5% Dextrose
Tetracaine 0.5% in 5% Dextrose
Procaine 10% in water
What is the baracity of Bupivicaine 0.3% in water?
Hypobaric
The 4 isobaric solutions listed in class are all mixed with what additive?
Saline
What is the only LA mixture (per the powerpoint slides) that is combined with water but is not a hypobaric solution?
Procaine 10% in water = Hyperbaric
High and Low (Peak and Trough) dermatome points in a SAB?
High: C3 and L3
Low: T6 and S2
SAB Dosing Table
In an epidural, while ensuring incremental dosing of 5 mls, we should be avoiding these 3 negative outcomes.
- Accidental “High Spinal”
- Hypotension from Rapid autonomic blockade
- LAST
Most common concentration of 2-Chloroprocaine for surgical anesthesia?
Why is this important?
3%
Higher concentration = faster onset
Adding NaHCO3 increases these 4 things:
- pH of LA
- Concentration of Non-ionized form
- Rate of diffusion
- Speed of the onset of the block
Alkalinization
The ___ of the LA is crucial for determining how high the anesthetic block reaches.
Volume
What is the initial dose of an epidural?
What about the top-up dose?
Initial: 1-2 ml/segment
Top-Up: 50-75% of initial dose
What aspect of a LA determines how strong/dense the block is?
Concentration
What are some positive outcomes to adding adjuncts to neuraxial anesthesia?
- Postoperative Analgesia
- Extends Duration
- Improves the density of the block
Which of the following drugs has been PROVEN to be the safest adjunct for neuraxial anesthesia?
A. Neostigmine
B. Ketamine
C. Versed
D. Clonidine
E. Magnesium
D. Clonidine
Rationale:
All of the other drugs are still listed as “Investigative agents” and need to be further studied in order to be validated.
True or False:
Vasopressors improve the density, duration and analgesia in neuraxial anesthesia?
FALSE
Vasopressors extend the duration ONLY.
Alpha-2 agonists improve the density, duration and analgesia in neuraxial anesthesia
Neuraxial Opioids target what area?
Substantia Gelatinosa of the dorsal horn (Lamina 2)
Do neuraxial opioids diffuse into the general circulation?
Yes: provides a more broad pain relief.
Examples of Hydrophilic Neuraxial anesthesia opioid adjuncts:
Morphine
Hydromorphone
Meperidine
Examples of Lipophilic Neuraxial anesthesia opiod adjuncts:
Fentanyl
Sufentanil
When comparing hydrophilic opioids to lipophilic opioids, describe the duration and spread:
Duration is longer in hydrophilic and spreads more widely in a rostral manner
Is the onset longer or shorter in Hydrophilic opioids?
What about systemic absorption?
Longer
Less systemic absorption
Intrathecal, Epidural, and epidural infusion doses for Sufentanil
- Intrathecal: 5-10 mcg
- Epidural: 25-50 mcg
- Infusion: 10-20 mcg/hr
Intrathecal, Epidural, and epidural infusion doses for Fentanyl
- Intrathecal: 10-20 mcg
- Epidural: 50-100 mcg
- Infusion: 25-100 mcg/hr
Intrathecal, Epidural, and epidural infusion doses for Hydromorphone
Intrathecal: N/A
Epidural: 0.5-1 mg
Infusion: 0.1-0.2 mg/hr
Intrathecal, Epidural, and epidural infusion doses for Meperidine
Intrathecal: 10 mg
Epidural: 25-50 mg
Infusion: 10-60 mg/hr
Intrathecal, Epidural, and epidural infusion doses for Morphine
- Intrathecal: 0.25-0.3 mg
- Epidural: 2-5 mg
- Infusion: 0.1-1 mg/hr
Occurrence of pruritis after giving an opioid adjunct in neuraxial anesthesia:
30-100% of the time
Prophylactic measures to try and prevent pruritis.
- Minimize morphine dose < 300 mcg
- Zofran
- Nubain
How long does the addition of A2 agonists extend the sensory and motor blockade?
Approximately 1 hour
Doses of Precedex and Clonidine as neuraxial adjuncts:
Precedex: 3 mcg
Clonidine: 15-45 mcg
Which of the following LA, when a vasoconstrictor is added as an adjunct, would cause the most profound increase in duration?
Lidocaine
Tetracaine
Bupivicaine
Tetracaine
What is the most worrysome risk of performing neuraxial anesthesia on a patient taking anticoagulants?
Epidural Hematoma
Symptoms of an Epidural Hematoma:
Lower extremity weakness, numbness
Lower back pain
Bowel/Bladder dysfunction
Treatment for Epidural Hematoma:
Surgical decompression **within 8 hrs **
With which patient population (taking anticoagulants) is neuraxial anesthesia a big challenge?
Patients with Cardiac Stents
What are the guidelines for holding ASA in High Risk, Intermediate Risk, Low Risk and central neuraxial cases?
High/Intermediate: Hold 4-6 days
Low: No hold
Central: No additional precautions
How long should we hold NSAIDs for High risk procedures?
Hold for 5 half-lives
Place these types of surgeries in either a Low, Intermediate or High cardiac risk level:
Prostate Surgery
Cataract Surgery
Breast Surgeries
Open Aortic Surgery
Orthopedic Surgery
Head and Neck Surgery
Peripheral Vascular Surgery
Endoscopic Procedures
Intra-thoracic/Intra-abdominal Surgeries
Prostate Surgery (Intermediate)
Cataract Surgery (Low)
Breast Surgeries (Low)
Open Aortic Surgery (High)
Orthopedic Surgery (Intermediate)
Head and Neck Surgery (Intermediate)
Peripheral Vascular Surgery (High)
Endoscopic Procedures (Low)
Intra-thoracic/abdominal (Intermediate)
How long should we hold Tirofiban/Eptifibatide prior to performing regional anesthesia?
What about abciximab?
4-8 hrs
24-48 hrs
Hold time for Plavix, Prasugrel, Ticlopidine prior to Regional Anesthesia:
Plavix: 5-7 days
Prasugrel: 7-10 days
Ticlopidine: 10 days
Unfractionated Heparin will inhibit which factors?
2, 9, 10, 11, 12
Hold times for Low, High and Therapeutic doses of UFH?
Low (< 5,000 U): 4-6 hrs
High (20,000 U): 12 hrs
Therapeutic (> 20,000 U): 24 hrs
Why might we insist on a PLT level prior to central neuraxial block?
If the patient has been on UFH for > 4 days
LMWH will inhibit which factor?
Xa
Hold times of medications (for regional anesthesia) in patients on therapeutic or prophylactic doses of LMWH:
Prophylactic: 12 hrs
Therapeutic: 24 hrs
How long should Warfarin be held prior to regional anesthesia?
Hold for 5 days, verify a normal INR
(<1.5)
The use of which type of anticoagulants are an absolute contraindication to neuraxial anesthesia?
Thrombolytic Agents
(t-PA, streptokinase, urokinase)
Hold time for direct oral anticoagulants prior to regional anesthesia:
(Apixiban, Xarelto, Pradaxa, etc…)
DC at least 72 hrs prior to procedure