anesthesia meds: Flashcards
pre-anesthetic meds:
- Benzos
- Barbiturates
- anti-histamines, phenothiazine, butyrophenes
intravenous anesthetics:
- barbiturates
- etomidate
- opioids
- ketamine
- propofol
Benzo’s:
Raise threshold for CNS toxicity of local anesthetics Reduce anxiety / “calming” effects Rapid onset and short duration of action Varying ability to cause amnesia Agents : Diazepam (little use) Lorazepam Midazolam Adverse events: Sedation Disorientation
Barbiturates:
May provide sedation and reduce apprehension
May yield disorientation if pain is present
Tolerance observed in patients with chronic use of alcohol
Onset: less than 1 minute / Duration: 5 – 10 minutes
Agents:
Pentobarbital
Thiopental
Adverse effects: Cardiac and respiratory depression
Avoid in: porphyria
Limited availability in US
Etomidate:
Potent ultra-short acting hypnotic without analgesic properties
Modulates signaling at GABAA receptors
Other uses include conscious sedation or rapid sequence induction for cardioversion
Must follow with analgesic and muscle relaxant drugs
IV injection of 0.3 mg/kg will induce sleep for 5 min
Side effects:
hypotension
carbon dioxide retention
suppresses corticosteroid synthesis at adrenal cortex
Opioids:
Selectively inhibit nociceptive reflexes and induce analgesia through action at mu receptors
Inhibit release of neurotransmitters including substance P
Antagonize effect of exogenous substance P
Morphine is associated with histamine release
Adverse effects:
Respiratory depression
Nausea / vomiting
Constipation
morphine dosing and duration:
1-2 mg
90 min
Fenanyl dosing and duration:
.05-.1 mg
30 min
Sufentanyl dosing and duration:
.005-.01 mg
15 min
hydromorphone dosing and duration:
.1-.2 mg
60 min
Ketamine
Used for induction of dissociative anesthesia
Often used for emergency surgical procedures
ER use with orthopedic indications
Use in children
Acts on receptors in cortex and limbic system
Onset of action is less than 1 minute
Associated with unconsciousness, analgesia, and amnesia
Adverse events: hallucinations, bad dreams, increased muscle tone
Propofol:
Chemically unrelated to other IV anesthetics
Oil emulsion at room temperature (1% solution)
Acts to potentiate GABA receptor activity and block sodium channels
Rapid onset of anesthesia
Effective for induction and maintenance
Adverse effects:
Significant respiratory depression (apnea)
Hypotension
injection site pain
inhaled anesthetics:
Used for induction and/or as adjuvant
Act to alter neuronal ion channels to decrease tissue excitability
Speed of induction is inversely associated with solubility in most body tissues
Agents:
Nitrous oxide (no muscle relaxant activity)
Sevoflurane
Isoflurane
Desflurane
Adverse effects: nausea, vomiting, malignant hyperthermia (rare), caution in patients with renal / hepatic dysfunction
local anesthetics:
Reversibly block nerve conduction around site of administration
Block nerve impulse conduction by inhibiting sodium channels
Decreases nerve cell membrane permeability to sodium ions
Decrease depolarization / increases excitability threshold
Prevents nerve action potential from forming
May be used for infiltration or nerve block
Infiltration preferred for:
Surgical procedures
Nerve block
Surgical or diagnostic procedures
Pain management
amino amides:
- metabilized hepatically
- drugs: lidocaine, bupivacaine, prilocaine, dibucaine
