Anesthetics Flashcards
Routes of Local Anesthesia
Topical
Infiltration
Epidural
Spinal
Epidural
High dose
Slow onset
Multiple dosing possible
Given at various points in backbone
Spinal
Low dose
Fast onset
Single dose only
Can only be given at specific site in backbone to avoid damage
Cocaine
First LA
LA Charecteristics
Potency- as lipophilicity increases so does potency
Onset of action- decreasing pKa speeds onset
General classes of synthetic cocaine derivates
Aminoesters- procaine, chloroprocaine
Aminoamides- Lidocaine, bupivicaine
MOA of LA
State dependent block of NA channels
Nociceptors
C fibers- slower sense pain
Black Mamba
Venom contains:
a-dendrotoxin (work on K+ Channels)
Mambaglins- which block ASIC ~type of NA channel opened by acid
Cone Snail
Prialt- specific blocker of Cav2.2 N-Type channels
Intrathecal analgesiac
Used for pain in morphine tolerant/Addict pts
GA Charecteristics
Modes of delivery: Inhalation/Injection
Sedation/hypnosis (loss of consciousness-ideally)
Immobility (but breathing)
Analgesia- no pain
Amnesia- dont want to remember the process
Measuring Inhaled anesthesia
MAC-moinimum alveolar concentration. Meausres the response of pts to a surgical stimulus. The lower the mac, the more potent the anesthetic.
Factors that can effect it- hair color, age lifestyle, medications.
MAC trends
More potent- more lipophillic
Less potent- less lipophillic
Are sleep an anesthesia equivalent?
No! Sleep is arousable, sedation can be arousable, GA is unarousable!
Partition trends
Lower # will be easier to partition (travel) to other parts of body. From alveoli, to blood, to brain
Ether
The first GA. No longer recommended by WHO MAC of 3.2 B/G partition of 12- v high MOA: PAM at GABA Agonist at GABA at high doses
NO
MAC over 100!
B/G Partition 0.46
Has to be used 50/50 with O2, can be used as an adjunct to other anesthetics
MOA:
weak PAM at GABA and Glycine
weak activator of K2P channels
Weak blocker of NMDA, AMPA, Kainate
Halothane/Isoflurane
Low macs, and good B/G partitioning MOA: Agonist at GABA and Glycine Antagonist at NMDA and NA channels Activates K2P channels
Isoflurane>Halothane due to hepotoxcity of halo.
Sevoflurane
Good mac and good B/G
Widely used- more expensive though
PAM at GABA
NMDA antagonist
K2P channel activator
Injectable anesthetics
More potent
Are often sedative hypnotics agents, used to induce anesthesia
TIVA can be used, with some precautions- though not often.
Main uses of injectable anesthetics
Thiopental- not commonly used anymore due to capital punishment, made it hard to get
Methohexital- ECT, lowers seizure thresholds
Propofol- most common induction agent
Ketamine- trauma, or unclear history. Will raise BP/HR
Etomidate– less commonly used, unless pt is hemodynamically unstable
Thiopental
Rapid onset (20-45s) Short acting <10 minutes, peak dose within ~1min Increases open time of GABA receptors Used to break status epilepticus
Methohexital
Rapid off-rate= fast recovery
Lowers seizure threshold ECT
Other sedatives/anesthetics must be used to break the seizure
Increases open time of GABA A receptor channels
Propofol
Rapid onset, anti emetic, anti seizure
Used to break status epilepticus
PAM at GABAa
NAv channel blcoker
Etomidate
Rapid onset, used in pt where history is unclear, or BP unstable
PAM at B2,B3 GABA, becomes an agonist at higher concentrations
Ketamine
Trauma
NMDA antagonist main MoA
SA’s
Esketamine
For MDD
Non competitive antagonist at NMDA
Xenon
High MAC!
Good B/G partition
Antagnoist at NMDA, however minimal SA’s compared to ketamine
Expensive, can we recycle it?
MOC etomidate
Maintain the Rapid onset of etomidate, and hemodynamic charecteristics.
Removes the decrease in cortisone.
