Pain Management + Local Anesthetics - Midterm Wrap Up Flashcards
(91 cards)
1
Q
Meperidine
A
Opioid Agonist at Mu & Kappa
Derived from Phenylepiperidine
2
Q
Meperidine’s structure is similiar to…
A
Atropine
3
Q
What analogues were developed from Meperidine?
A
All the Fentanyl’s
4
Q
Meperidine Metabolism
A
90% Hepatic
Demethylation to Normeperidine –> Meperidinic Acid
Excreted by Kidneys
Renal Impairment = Buildup
5
Q
Meperidine Pharmacokinetics
A
3-5 hr. Half-Life
Protein Bound
6
Q
Normeperidine
A
1/2 Analgesia of Meperidine
15 hr. Half-life; > 35 hrs. for renal pts.
CNS Stimulation & Toxicity - myoclonus + seizure
Demerol Delirium
7
Q
Meperidine CV Effect
A
Decrease SNS Reflex
Orthostatic Hypotension > Morphine
Tachycardia (Atopine-like)
Big Dose = ↓Inotropy
8
Q
Meperidine Respiratory Effect
A
Ventilation depression > Morphine
9
Q
Meperidine Serotonin Syndrome
A
Autonomic Instability
- HTN
- ↑HR
- ↑Temp + Diaphoresis
- Rigidity
- Hyperreflexia
- Confusion
- Coma, Seizure
- Coagulopathy
- Metabolic Acidosis
10
Q
What to give for Post-Op Shivering?
A
Demerol: 12.5 - 25 mg
Sufentanil, Ultram, Clonidine, Ketamine
11
Q
Slide 77
A
12
Q
Methadone
A
Mu Agonist + NMDA Antagonist
Variable 8-60 hr. Half-life
(Unpredictable)
QT Prolongation
13
Q
Opioid Agonist-Antagonist Meds
A
Pentazocine
Bremazocine
Dezocine
Naluphine
Buprenorphine
Nalorphine
Butorphanol
14
Q
Opioid Agonist-Antagonist
A
Binds to Mu (+ delta, kappa)
Part Agonist: limited Mu effect
Part Competitive Antagonist: no mu effect
Effects subsequent Opioid administration
15
Q
Opioid Agonist-Antagonist Advantages
A
Pain relief w/ limited ventilation depression
Low addiction risk
Effect Ceiling, but can still die
For pts. who cant tolerate pure opiates
16
Q
Opioid tolerance can occur ______ dependence.
Opioid dependence cannot occur ________ tolerance
A
Tolerance can occur without dependence
Dependence cannot occur without tolerance = addiction
17
Q
Opioid Antagonists
A
Small structural changes convert agonist into antagonist
Subbing alkyl for methyl group
18
Q
What is the N-alkyl derivative of Oxymorphone?
A
Naloxone
19
Q
What are the Pure Opioid Antagonists?
A
Naloxone
Natrexone
Nalmefene
20
Q
Opioid antagonists and the Receptor
A
High receptor affinity
Bumps off agonist and binds to mu receptor for antagonism
21
Q
Naloxone
A
Nonselective Antagonist at all 3 Opioid Receptors
22
Q
What does nalaxone do?
A
Treats ventilation depression
(also treats newborn with opioid mom)
Reverses Overdose
Detects Physical Dependence
23
Q
Naloxone Duration of Action
A
30-45 min
24
Q
Naloxone Metabolism
A
Liver Enzymes
60-90 min Half-life
May redose
25
Naloxone Side Effects
Return of Pain
NV r/t Injection Speed
Sympathetic Outflow
(Tachy, HTN, P. Edema, Dysrhythmias)
26
Tramadol
Mu Agonist
Weak SNRI
No metabolite
Interacts with SSRIs
27
Tramadol Contraindication
Seizure Disorder
Can also cause new onset Seizure
28
NSAIDs MOA = COX Inhibition
| (Cyclo-Oxygenase Enzyme)
Platelet Inhibition + GI Mucosal Thinning = Bleed
29
Toradol
COX**2** Inhibitor - Celecoxib - no mucosal thinning effect, but still has platelet inhibition
* Black Box Warning - GI Bleeds, Peptic Ulcers, Bleeding in General
* Contracindicated for Labor & Deliver - inhibits fetal circulation
30
Toradol Side Effects
ARF
GI
CHF
Platelet Malfunction
31
Ofirmev
15 min Onset
4-6 hr. Duration
Liver Toxicity
MOA: reduced PG production, weak COX inhibition
Napqi metabolite, mucomyst binds to makes it non toxic
32
Endocannabinoid System
2 Major: 2AG & AEA
Slows Down Pain Impulses by **reducing cAMP**
Lipophilic
CB1 Receptor on Postsynaptic Terminal
Inhibits Ca++ --\> Inhibits Neurotransmitter release
33
Where are CB1 Receptors Found?
Everywhere
Brain, Liver, Reproductive System, CV System
Skeletal Mucles, GI
34
Where are CB2 Receptors?
Pheripheral Tissues
Immune Cells
35
THC
Psychoactive
**CB1 Agonist**
Weak CB2
CYP Metabolized
Antiseizure, muscle relaxant, ↑appetite, antioxidant, sedative
36
CBD
Not Psychoactive
Reduces THC effects
Low CB1 & CB2 affinity
CYP Metabolism
Anxiolytic, Anti-Seizure, Antioxidant
37
Cannabis Side Effects
Tachycardia
HTN
Cough, Wheeze, Sputum
Euphoria, Disorientation, Confusion
Psychosis, Depression
38
What is Gabapentin Used For?
Used for Neuropathy \> Seizure Control
39
Gabapentin MOA
Blocks Alpha 2 Delta Ca+ Channels --\> Increases GABA reduction in Glutamate
40
Gabapentin for Post-Op Pain
Give PreOp
Improved Post-Op Pain
Reduce Opiate Requirement
Highest Risk: Increased PostOp Sedation
41
Gabapentin ADRs
Well tolerated
Neutropenia
Dizziness/Ataxia
Fatigue
Nystagmus/Diplopia
NV
**Gabapentin + Opiate = Severe Resp. Distress**
42
Local Anesthetics
Reversibly block electrical impulses along nerve fiber
43
What happens to the nerve fiber when you remove the Local Anesthetic?
Spontaneous & Complete return of nerve conduction w/o damage
44
What is the effectiveness of a Local Anesthetic dependent on?
Physiochemical Properties of the Anesthetic
&
Anatomy of Nerve being Blocked
45
What is the Axolemma
Cell membrane of an axon
46
What are Schwanna Cells
Cells that cover the axon(s)
47
Nodes of Ranvier
Nerve segments b/t Schwann cells that dont contain myelin
48
What is Saltatory Conduction?
Jumping of Action Potentials from node to node
49
Fasciculi
Bundles of Axons
50
How do Local Anesthetic effect Actional Potentional?
Hyperpolarizes and keeps the nueron to just below resting potential
51
A-Alpha Fibers
Biggest Diameter
Most Myelination
Fastest Conduction
Motor Function & Propioception
52
A-Beta Fibers
4-15µm Diameter
Second Fastest Conduction
Motor, Touch & Pressure Sensation
53
A-Gamma Fibers
4-15µm Diameter
Muscle Spindles & Reflex
54
A-Delta Fibers
3-4µm Diameter
Slowest Conducting A Fiber
Pain & Temperature Sensation
55
B Fibers
4µm Diameter
Slower Conduction & Less Myelination than A FIbers
Preganglionic Autonomic Nerves
56
C Fibers
1-2µm Diameter
Slowest Conduction
Pain & Temperature Impulses
**Unmyelinated**
57
Less Myelination makes the neuron ________ sensitive to Local Anesthetics
Less Myelination makes neuron **more** sensitive to LA
58
How do Local Anesthetics work on Spinal Nerves
B Fibers --\> C FIbers --\> A Fibers
Motor Sensation is lost last
59
Local Anesthetic MOA
Reversibly Block Na+ Channels
Receptors are inside cell and like the **charged form** of LA.
Lipophilic to enter cells, w/ an ionized portion to bind
60
Local Anesthetics Chemical Structure
Unsaturated Aromatic Ring
Tertiary Amine
Intermediate Carbon Group **- where they differ**
61
What are the different Intermediate Groups for Local Anesthetics?
Ester & Amide
Determines how it will be metabolized and allergy potential
62
Local Anesthetics - Esters
No "i's" in the first part of name
Procaine
Chloroprocaine
Tetracaine
Cocaine
63
Local Anesthetics - Amides
Lidocaine
Prilocaine
Mepivacaine
Ropivacaine
Bupivacaine
Levobupivacaine
Etidocaine
64
What determines Local Anesthetic Onset of Action?
Lipid Solubility / Amount of Non-Ionization
pKa
65
Local Anesthetic with a pKa closest to physiological pH will have a _________ concentration of non-ionized form
Closer to Body's pH = Higher Concentration of Non-Ionized Form
66
How do Local Anesthetics travel in the body?
Injection of LA --\> Non Specific Tissue or Blocks Nerve ---\> Bloodstream -- Systemic tissue distribution --\> Liver ---\> Renal Excretion
67
What effects Local Anesthetic Duration of Action?
Highly lipid soluble = longer duration
Highly lipid soluble also = more protein bound
68
Converting Local Anesthetic Percentage of Concentration to mL
1. Take percentage number, add "gram"
2. Put that number over "100 mL"
3. Convert to milligrams
Ex:
1% ---\> 1gram/100mL x 1mg/.001gram = **10mg/mL**
69
Local Anesthetics Pharmacokinetics
LA's are meant to stay in area of injection
Higher LA concentration = Faster Onset
Systemic Absorption = termination of effect
70
What does systemic absorption of Local Anesthetics depend on?
Blood Flow
71
How does Epinephrine effect Local Anesthetics?
↑Duration of Action
↑Nerve Uptake
↑Analgesia Quality
↓Systemic Toxicity
↓Vascular Absorption
72
Local Anesthetics blocks sodium channels
What else can happen because of this?
Vasodilation, increasing LA absorption, limiting its duration and increases toxicity
**Does not apply to**
Cocaine
73
Which highly perfused organs are responsible for initial uptake of Local Anesthetics?
Brain
Lung
Heart
Liver
Kidney
74
Which moderately perfused tissues provide the greatest reservoir for Local Anesthetics
Muscle mass due to its large mass
75
What are Procaine and Benzocaine metabolized into?
P-Aminobenzoic Acid (PABA)
↑Allergic potential
Persian, Jewish, Alaskan have high risk for abnormal pseudocholinesterase
76
Amide LA Metabolism
* **Liver Enzymes** - P450
* Rate of Metabolism
* Prilo\>Lido\>Mepiva\>Ropiva\>Bupiva
* ↓Liver Function = ↑Toxicity
77
Buildup of which metabolites convertes Hgb to Methemoglobin?
Prilocaine & Benzocaine Spray metabolites
Treat with Methylene Blue: 1-2mg/kg over 5 min
78
Signs an Symptoms of Methemoglobinemia
Brown Gray Cyanosis
Tachypnea
Metabolic Acidosis
79
What are added to Local Anesthetics to increase the Safety, Quality, Intensity, and Rate of Onset?
Opioids
Sodium Bicarbonate
Epinephrine
80
What else factors into Local Anesthetic Toxicity?
Accidental Intravascular Injection
and
Excessive Dose
81
Cardiac Effects of Local Anesthetic Toxicity
As toxicity inceases....
HTN & Tachycardia --\> Bradycardia, Hypotension, Arrythmias --\> Asystole
82
Cerebral Effects of Local Anesthetic Toxicity
As toxicity increases...
Mental Abnormalities --\> Confusion, Dizziness, Tinnitus, Metal taste --\> Seizure
83
Local Anesthetic CNS Toxicity Management
1. Assure Adequate Airway & Ventilation
2. Give Anti-seizure Med
CNS Toxicity can progress to Cardiac Arrest
84
How does Local Anesthetic Toxicity in the CV compare to CNS?
CV is more resistant to Toxicity
CV Toxicity = Super Bad, No Antidote
85
Local Anesthetic Cardiovascular Toxicity
LA slows everything down
* Reduces heart automaticity, refractory period, contractility & conduction
* Vasodilation
* Bradycardia + Heart Block + Hypotension = Cardiac Arrest
86
What happens if you accidentally give Bupivacaine Intravascularly?
Severe Cardiotoxicity
To fix, you need HIGH doses of pressors & prolonged resuscitation effort.
87
What is Intralipid?
10-30% Lipid Emulsion
Binds with Lipophilic LA rather than just let it float around in bloodstream
Propofol wouldn't work for this
88
Transient Neuro Symptoms of Spinal Anesthesia
Dysesthesia, Burning, Lower Extremity & Butt Aches
Lasts 10 days - 2 wks
Lidocaine: 13% Incidence, then Bupivicaine is #2
89
What is a Eutectic Mixture (EMLA)
Adding two liquids together = solid (creams)
Apply 1 hr before for effect
90
What is the risk for applying Local Anesthetics to Mucous Membranes?
Absorption to systemic circulation & toxicity
91
Topical Cocaine
Unique d/t Vasoconstriction
Blocks Epi & Norepi Uptake - Ventricular Arrhythmias
B-Blocks increase HTN = stroke & MI
