PHARM - anesthetics Flashcards
five major effects of general anesthesia
1) unconsciousness
2) amnesia
3) analgesia
4) inhibition of autonomic reflexes
5) skeletal muscle relaxation
describe the anesthesia induction process
- IV anesthetic until unconscious
- management with inhaled or IV
- muscle relaxant if intubation required
- anti-anxiety at the beginning if needed
describe maintenance of anesthesia
- inhaled or IV drugs
- monitoring of vitals
- use of opioid for pain, such as fentanyl
example of a reversal agent for muscle relaxants
neostygmine
how does general anesthesia work?
reduce excitatory stimulation - ACh (nicotinic/muscarinic) - excitatory amino acids (NMDA, Kainate, AMPA) - serotonin (5-HT) increase inhibitory stimulation - GABA, glycine - potassium channels
list these inhaled anesthetics in terms of solubility and discuss onset and recovery: nitrous oxide, halothane, isoflurane, sevoflurane
least soluble - nitrous oxide - rapid, rapid (incomplete)
low solubility - sevoflurane - rapid, rapid
mid range solubility - isoflurane - middle, middle
most soluble - halothane - middle, middle
relate opioids to inhaled anesthetics
can depress respiration and make induction take longer
what is anesthetic potency?
minimal alveolar concentration needed to prevent response to a surgical incision in 50% of cases
alveolar concentration formula that should work for 95% of patients
1.3xMAC
4 stages of anesthesia depth
1) analgesia - awake to drowsy
2) excitement - delirium, proposal can eliminate this
3) surgical anesthesia - muscles relaxed, breathing regular, no more spontaneous movement, careful monitoring
4) death
physiological effects of anesthesia on brain
- decrease metabolic activity
- decrease blood flow
- vasodilation
physiological effects on cardiovascular system of anesthesia
- contractility down
- ## MAP down
resp effects of anesthesia
- decrease tidal volume
- increase RR
why does propofol go strait to the CNS quickly?
lipid solubility
how is propofol administered?
IV
local anesthetics can be divided into two categories…
esters
amides
what are the local esters and how are they used?
- benzocaine, cocaine - surface action
- procaine - short acting
- tetracaine - long acting
what are the local amides and how are they used?
- lidocaine - medium acting
- bupivicaine - long acting
contrast metabolism and half life of amides and esters
esters - minutes, broken down by pseudocholinesterases
amides - 1.5-3.5 hours, broken down by P450 enzymes
how do local anesthetics work?
block voltage gated sodium channels preventing action potentials
characteristics of nerves better suited for local anesthetics
- narrower
- heavily myelinated
- peripheral
- rapidly firing
which inhaled anesthetic can lead to megoblastic anemia?
NO2
isoflurane - type, PD, PK
- inhaled general
- PD - unknown, lipid soluble, potentiates GABA, opens K+
- PK - lungs 95%
sevoflurane - type, PD, PK
- inhaled general
- PD - unknown, GABA and K+
- PK - lungs primarily, 5% liver
