Anesthetics Flashcards
General anesthetics
Agents used to induce controlled unconsciousness, usually for surgery.
Local anesthetics
Agents used for local numbing of area for small surgeries inducing local analgesia.
3 results of anesthetics
Analgesia - relief from pain
Amnesia - no memory of surgery
Immobility - loss of skeletal muscle movement.
Pros/cons of anesthetics
Rapid induction
Minimal long lasting results
Rapid recovery
High dose needed - narrow window.
General anesthetic mechanism.
Binds to specific proteins that affect ion influx and inhibit neurotransmitters.
Ion channels affected by anesthetics
Primarily Na+ and Ca+
Others:
Nicotinic
Glycine
Serotonin
2 pore K+
Stages of anesthetics
- Analgesia - euphoria and amnesia
- Excitement - delirium, combative behaviour (anesthesiologists minimize this time)
- Anesthesia - unconsciousness, decreased muscle contraction widespread.
- Medullary depression - Cardiac arrest, respiratory arrest (avoided)
Mode of delivery of anesthetics
Intravenous or inhaled
Pre-anesthetic evaluation
Medical history, previous anesthetics. age, weight, teeth condition, airways assessment.
Day or surgery
Best combination of drugs to achieve target result
Fating
Airway management
How to prevent too much time in stage 2?
Intravenous anesthetics induce onset in less than 20 seconds. Once the patient is under, anesthetics are given inhalationally.
Examples of anesthetic drugs
Propofol
Barbiturates - sodium thiopental
Ketamine - conscious but insensitive to pain.
Pros and cons of propofol
Rapid response, no accumulation, rapid recovery, given in two ways, anticonvulsant
Causes apnea, lowers blood pressure, no analgesia properties.
Pharmacokinetics of propofol
Highly protein bound, 2-24hour half life, metabolized in the liver.
Mix of gases in anesthetic inhalation
Oxygen, nitrous oxide and volatile anesthetic agent.
Volatile anesthetics
Halothane
Enflurane,
Isoflurane
Gaseous anesthetics mode of action
Potentiate GABA receptors and block glutamate receptors, inhibiting postsynaptic neurotransmitters.
GABA receptors
Ionotropic ligand-gated ion channels primarily responsible for mediating fast synaptic inhibition in the central nervous system.
Nicotinic receptor
Ligand gated ion channels that mediate fast neurotransmission in the central and peripheral nervous systems
TREK (background leak) potassium
channel
Are open even at rest and contribute to the resting membrane potential
Reversing agents of anesthetics
Flumazenil - GABA receptor reverse
Naloxone - reverses the effects of opioids
Neostigmine - Acetylcholinesterase inhibitor
Types of local anesthetics
Ester linked - cocaine, procaine, - unstable in solution, fast acting pseudo-cholinesterase metabolism.
Amide linked - Lidocaine, bupivacaine, - stable, metabolized in the liver
