General Anaesthetic (General) Flashcards
General Anesthetic
Exerts its effects on CNS leading to loss of sensation and consciousness
Local Anesthetic
Blocks peripheral nerve conduction and all sensation. No loss of consciousness
Analgesic
Selectivity blocks sensation of pain without blocking other modalities
Anesthetic vs Analgesia
Anesthetic = Loss of sensation/consciousness (motor and autonomic)
Analgesia = Loss of painful sensation
How are general anesthetics administered.
What are the two methods of administration
Administered systemically
–> Allows them to disperse everywhere
Intravenous Administration
Inhalation Administration
Intravenous vs Inhalation (Onset)
Intravenous is more rapid than Inhalation
Intravenous vs Inhalation (Elimination Speed)
Intravenous has slow elimination, will last a while in circulation
Intravenous vs Inhalation (Metabolic Degration)
Inhalation drugs enter through lungs and undergo metabolic degration
What anesthetic route is best for induction?
Intravenous Agents
What anesthetic route is best for Maintaining Anesthesia?
Inhalation Agents
- Intravenous Agents must be continuously administered
What determines the kinetics of inhalation drugs
Inspired air and Blood stream
Intravenous vs Inhalation (Maintenance Anesthesia)
Intravenous has slow recovery –> Not used for maintenance
Inhalation has quick elimination –> Can be used for maintenance
Intravenous vs Inhalation (Metabolism)
Intravenous requires body to metabolize drug
–> Slow Metabolism
Metabolic Degradation does not play a role in Inhalation and does not effect duration of action
Lipid Soluble effect on General Anaesthetic
The more lipid soluble a drug is the more potent it is
Where do anaesthetics bind
Hydrophobic pockets of specific membrane proteins
What do general anesthetics affect (neural)
Decreases neuron excitability rather than axonal conduction
Main Mechanism of General Anaesthetic
GABA(A) Receptors
General Anaesthetic potentiate action of GABA –> Enhances Cl- entry intro cells causing Hyperpolarization
Main Mechanism of Inhalation Anaesthetics
Two Pore Domain K+ Channels causing Hyperpolarization
Main Mechanism of Nitrous Oxide and Ketamine
NMDA Receptors
Drugs bind to receptors reducing/blocking NMDA Receptor Response
Blood:Gas Partition Coefficient
Measures solubility in blood
What does a low Blood:Gas Partition Coefficient mean
Low Coefficient = Lower Solubility = Faster onset/offset of anesthesia
(Due to faster equilibrium with alveoli)
Oil:Gas Partition Coefficient
Measures solubility in fat
What does a High Oil:Gas Partition Coefficient mean
High Coefficient = High Lipid Solubility = High Potency = Delays Recovery from Anaesthesia
Balanced Anaesthesia
Mixing other drugs so that anaesthesia provides other effects
- Sedative
–> Benzodiazepine
- Prevent Bradycardia
–> Atropine
- Neuromuscular block for relaxation
–> Vecuronium
- Reverse neuromuscular block
–>Neostigmine
- Analgesic for pain:
–>Morphine
