Blocks/ Epidurals/ Pain Management Flashcards
What are opioids/ narcotics?
Bind to Mu, Delta, Kappa receptor sites to produce morphine like or opioid agonist effect by acting on pain modulating system. Can be natural or synthetic. Caution: watch out for respiratory depression.
What is morphine?
Prototype for strength of other narcotics
Can cause histamine release
Can cause spasm of biliary smooth muscle
Useful in treatment of angina in ACS
Peak effect in 20 minutes
Morphine facts
Route IV
Dose 2-15mg
Onset < 1 minute
Peak 20 minutes
Duration 2-7 hours
What is hydromorphone?
6x more potent than morphine
Recommended in renal patients d/t lack of active metabolites
Hydromorphone facts
Dose 0.5 - 2mg IV
Onset < 60 sec
Peak 5 - 20 min
Duration 2 - 4 hrs
What is fentanyl?
100x more potent than morphine
Can cause fixed chest syndrome
Fentanyl facts
Dose 0.05 - 2mcg/kg IV
Onset < 30 sec
Peak 3 - 7 min
Duration 30 - 60 min
What is fixed chest syndrome?
Can be caused by rapid IV injection of Fentanyl
Leads to bronchial constriction and resistance to ventilation, rigidity of diaphragmatic and intercostal muscles.
Reversal - administer subclinical dose of succinylcholine (w/c will relieve rigidity of chest wall?)
Additional action - Ventilate
What is Meperidine?
1/10x as potent as morphine
Primary for post operative shivering
Not commonly used for pain
Contraindications
a. Use of MAOIs - d/t resp depression w/ concurrent use of meperidine
b. potentiates seizure
What are commonly prescribed MAOIs?
Selegiline
Isocarboxazid
Phenelzine
Tranylcypromine
Meperidine facts
Dose 12.5 - 25 mg
Onset 1 - 3 min
Peak 5 - 20 min
Duration 2 - 4 hrs
What is opioid overdose treatment?
Naloxone
0.2 - 0.4mg reverses respiratory depression
Titrate 0.04mg to avoid acute reversal of analgesia
What are advantages of local anesthesia?
Postop analgesia on site
Safe for patients with systemic disease
Fewer side effects (PONV, sedation, respiratory depression)
What are the disadvantages of local anesthesia?
Toxicity
Allergic reaction
IV injection
Inadvertent infiltration
What are types of local anesthetics?
Esters (one “i”)
1. Cocaine
2. Procaine
3. Chloroprocaine
4. Tetracaine
What are types of local anesthetics?
Amides (two “ii”)
1. Prilocaine
2. Lidocaine
3. Mepivacaine
4. Bupivacaine
5. Etidocaine
6. Ropivacaine
What to watch out for in administering Prilocaine (Amide - local anesthetic)?
!Can cause methemoglobinemia
d/t prilocaine toxic build up
!s/s tachypnea, brown grey cyanosis, metabolic acidosis, chocolate colored blood
tx with methylene blue
What to watch out for in administering Bupivacaine (Amide - local anesthetic)?
!Do not use for bier block
!Can cause cardiac toxicity if excessive dose or accidental injection
Blocks sensory more than motor function
What to watch out for in administering Mepivacaine (Amide - local anesthetic)?
!Do not use for spinal anesthesia
!Great alternative to lidocaine with epinephrine without vasodilation effect
How are local anesthetics metabolized?
Esters - hydrolyzed by plasma cholinesterase (aka acetylcholinesterase, produced by liver and also breaks down succinylcholine)
Amides - metabolized by liver
What are important properties of local anesthetics?
Onset
1. Amides with more rapid onset
2. Site infection and acidosis slows onset
3. Increased risk of toxicity with hypoxia and acidosis
4. Adding bicarbonate speed onset and decreases duration of effect
What are important properties of local anesthetics?
- Adding vasoconstrictors (epinephrine) slows absorption of local anesthetics
- Adding vasoconstrictor decrease bleeding
- Absorption is dose related
- Highly vascular areas with faster systemic absorption
What is local anesthesia CNS toxicity?
Can occur d/t accidental injection into blood vessel or overdose
What are the signs and symptoms of local anesthesia CNS toxicity ?
!Circumoral numbness
!Lightheadedness
!Tinnitus
!Metallic taste in mouth
!Slurred speech
!Muscle twitching
!Can progress to grand mal seizures and coma
What is the treatment for local anesthesia CNS toxicity ?
!Apply oxygen at first signs.
May administer versed, valium, or thiopental for seizure activity
What are other treatments for local anesthesia CNS toxicity?
- Early detection
- Support circulation with fluids, vasopressors, antiarrhythmics
- Oxygen, airway management
- Control seizure activity
What are other treatments for local anesthesia CNS toxicity?
- CPR/ ACLS if necessary
- ! Lipid infusion
20% lipid emulsion for reversal of toxicity
IV Push - 1.5mL/kg over 1 minute
Infusion - 0.25mL/kg/min
What is local anesthesia cardiovascular toxicity?
!most common with Bupivacaine
d/t blocking of sodium channels in the heart
s/s includes hypertension leading to hypotension, PVCs, prolonged PR interval, CV collapse
What are the types of regional anesthesia
Topical anesthesia
Field block/ local infiltration
IV injection
Peripheral nerve block
Sympathetic nerve blocks
Neuraxial blocks (spinal, epidural)
What are topical and local infiltration for regional anesthesia?
Topical - Applied directly to Skin, Mucus Membranes, Urethra, Nose, Pharynx
Local Infiltration - Direct tissue injection, Blocks transmission of sensory impulses, Epinephrine can be injected into confined spaces
What is Bier Block (IV injection)?
Never use Bupivacaine for Bier Block ! d/t can cause cardiovascular collapse
Tourniquet applied to occlude circulation of arm or leg
Large doses of local anesthetic injected and stays in area d/t tourniquet
Risk of toxicity when tourniquet released d/t anesthetic can travel to systemic circulation
Common application: ganglion cyst removal, carpal tunnel release, tendon release