Intro To Anesthetics Flashcards
3 steps of Pain neurophysioplogy
1) initiation =(receptor activation)
2) propagation =(site to spinal cord to thalamus)
3) perception =(sematosensory, emotional, cognitive brain centers)
Local/peripheral anesthetics
- close to source
* Novocaine, Cocaine
Central analgesics
- supraspinal + spinal sites
* Morphine, NSAIDS
General Anesthetics
- Loss of consciousness
* Propofol, Etomidate, Barbituates)
Local anesthetic agents
Rx
- Benzocaine
- Cocaine
- Procaine
- Lidocaine
- Ropivacaine
Adjuncts
Rx
- Epi
- Clonididne
- Diazepam
Pain receptor on Nociceptor that lets in Na+
TRP Channel
How sensitize receptor to more pain?
*Pain (C?) fiber releases substance P, attracts macrophages, release prostaglandins, more pain
How pain pathway causes edema?
C fibers release Substance P —> attract mast cells —> release cytokines —> edema
A delta pain fibers vs. C fibers
fibers intercept pain stimulus then synapse to…?
A delta =*Neospinothalamic neuron (2nd order neuron)
C =* Paleospinothalamic neurons
Myelinationf/Pain type
A delta vs. C pain fibers
A delta = myelinated (First Pain - Sharp)
C = UNmyelinated (Second pain - dull)
NSAIDS
MOA
Block COX2 to stop PG production to stop C and A-delta-fiber sensitization
LAs + NSAIDS
Block 1st or 2nd pain?
Block 1st + 2nd pain
Blocks which activation states of Na channel?
- TTX
- Other LA
- Any state
* ONLY Activated (always) + Inactivated (sometimes) = Use-Dependent Blockade
LA structure
What increases Lipophilicity?
- # Carbon chains + length both sides
- Mid-Carbon chain length
= FAST ONSET, UP POTENCY
Structure of LA
Amide link
- Prototype
- I’s
- T1/2
- Lidocaine
- 2 I’s
- Long t1/2 = liver metab, unable to cross cell membrane (proton acceptor/weak base)
Structure of LA
Ester link
- Prototype
- I’s
- T1/2
- Procaine
- 1 I
- Short t1/2 = plasma + liver metab
MORE LIKELY ALLERGIC RXN
LAs block more
- diameter
- myelination
- Fire frequency
- Fiber position
- small diameter
- myelinated>unmyelinated
- Use-dependent
- External fibers blocked more than internal
Topical Anesthesia
Rx
- Benzocaine
- Lidocaine
ENT, DENTAL PAIN w/ PROCEDURE
Infiltration anesthesia
Rx
- Procaine
- Lidocaine
INJECT SUB-Q, MUC. MEMBRANE
Bier block
Rx
*Lidocaine
INJECT ARM W/ TOURNIQUET
Peripheral Nerve Block
Rx
- Lidocaine
- Ropivacaine
AROUND NERVE/PLEXUS
Epidural Anesthesia
Rx
- Procaine
- Lidocaine
CHILDBIRTH
Spinal Anesthesia
Rx
- Procaine
- Lidocaine
PROCEDURES W/ TRUNK
What increases Systemic Toxicity Risk with LA?
How to reduce?
DENSE VASCULATURE
Intercostal> caudal > epidural > brachial plexus > sciatic nerve
REDUCE w/ Epi!
High LA systemic absorption effects
- Brain
- Heart
- Brain (Gaba A blockade)= anxiety, confusion, tremor/convulsion (tx= Valium (benzo))
- Cardio = hypoTN, bradycardia (BUT COCAINE = tachycardia, vasoconstriction) =. (Tx= cardio rescuscitation/bypass, IV lipid emulsion
Allergies from which LA type?
Esters
From PABA
Clonidine
*MOA
*a2 on C/A-delta fiber (dorsal horn) = lowers pain transmission (less sub P/glutamate)
Cocaine
- ester
- ENT procedures
- ONLY LA = Tachycardia, vasoconstriction
Procaine
- 1st synthetic local anesthetic
- slow onset, short duration
- for Infiltration/Periph Nerve Blocks
Lidocaine
MC
- Amide
- Vasodilation, so combine w/ Epi
- Class 1B anti-arrythmic (Na+)
Ropivacaine
- S-isomer ONLY = low cardiac Na channel affinity, LOWER CARDIO TOXICITY
- R-isomer high cardiac affinity
