General & Local Anesthetics Flashcards
(59 cards)
What is a drug-induced reversible depression of the CNS resulting in loss of response to and perception of all external stimuli?
General anesthesia
What is a drug-induced state during which px respond normally to verbal commands?
Mnimal sedation (anxiolysis)
What are the stages of anesthesia?
- Stage 1 = Amnesia & Analgesia
- Stage 2 = Delirium/Disinhibition
- Stage 3 = Surgical stage
- Stage 4 = Respiratory paralysis (should not be reached)
How is respiration in the earlier stages of Anesthesia?
errratic or rapid in earlier stages & slow to shallow as it progresses to 3rd
What happens to eyeball movement in the stages of anesthesia?
greatest in stage 2, lesser in stage 3 (1st plane)
What happens to pupillary sizes in the stages of anesthesia?
pupils more dilated as px becomes more sedated
What are the diff anesthetic techniques?
-
Balanced anesthesia:combi of anesthetics & techniques to selectively direct components of anesthesia (inhaled & IV anesthetics)
Total IV Anesthesia:**only IV gen anesthesia
**Monitored Anesthesia care: Local anesthesia + oral/parenteral sedatives/anesthetic agents + monitoring of the px
*IV induction: IV + monitor + rapid acting IV anesthetic for induction
What are the 2 types of inhaled anesthetics?
Volatile = Low vapor pressure, high boiling pt, liquid @RT (halothane, enfluoprane, isoflurane, desflurane, sevoflurane
Gaseous = high vapor pressure, low boiling point, gas @ RT (Nitrous oxide, Xenon)
In the elimination of anesthetics, what is the metabolic hierarchy of the diff inhaled anesthetics?
(Most to least metab)
Halothane > Enflurane > Sevoflurane > Isoflurane > Desflurane > N2O
Is N2O metabolized in humans?
no, but bacteria in our GIT can break them mdown
What is the minimum conc of anesthetic in the alveoli that prevents movement in response to surgical stimulation in 50% of px?
Minimum alveolar concentration (MAC)
What is the measure of anesthetic potency?
lower the MAC, more potent agent
higher the MAC, less potent the agent
What is the ratio of dissolved gas (by volume) in** 2 tissue compartments** at equilibrium?
refers to solubility also
bloodg gas partition coefficient
what is the rel of anesthetic solubility in blood to rate of rise?
the less soluble it is in the blood, the faster the rate of rise of the inhaled anesthetic to alveolar gas -> faster px falls asleep –> INC conc in brain
Which of the anesthetics is not used clinically anymore bcos of its nephrotoxicity effect?
Methoxyflurane
What is the most potent anesthetic?
Halothane (lowest MAC)
What are the diff Blood:gas partition coefficient rel?
- **Higher PC **= Higher solubility = Slower induction = Longer effect
- **Lower PC **= Lower solubility = Faster induction = Shorter effect
What are the effects of anesthetic to the CNS?
- DEC cebral metab rate -> DEC cerebral blood flow
- <1 MAC = no vasodilation
- > or equial to 1.5 = vasodilation
- DEC PaCO2 via hyperventilation -> cerebral vasocontriction
- NO2 = INC Cerebral blood flow
What are the effects of anesthetic to the CVS?
- Myocardial depression -> DEC arterial BP (Halothane & Enflurane)
- Peripheral vasodilation min effect on CO so good for px with cardiac failure (Isoflurane, Desflurane, Sevoflurane)
- N2O: slight myocardial depression & SNS activation -> preserves CO
- Baroreceptor reflex (DEC BP, INC HR): Depressed: Halothane, Enflurane, Sevoflurane
Unaffected: Isoflurane, Desflurane
* DEC myocardial O2 consumption
What are the effects of anesthetics to respiration?
- Bronchodilating
-
Pungency of Isoflurane & Desflurane (irritating)
Respiratory depression: DEC response to CO2, INC apneic threshold - DEC Mucocillary functions: mucus plugging -> atelectasis, pulmonary infection
What are the effects of anesthetics to the kidneys?
- DEC GFR, urine flow
- DEC renal blood flow, INC filtration fraction
- depends on minor or major surgery
- resversible on discontinuation of anesthetic
What are the effects of anesthetics to the liver?
- Concentration-dependendent DEC of portal blood flow
- Hepatic artery flow may INC & preserve total hepatic blood flow
- transient changes in liver enzymes
What are the effects of anesthetics to the uterine smooth muscle?
- concentration-dependent uterine relaxation
- profound uterine relaxation at higher dose of inhaled anesthetic & is necessary if intrauterine manipulations, extraction of retained placenta, bleeding after delivery under GA
What are the sites of anesthetic targets of Inhaled anesthetics?
INC inhibitory synaptic activity - mediated by GABA
DEC excitatory activity - mediated by Glutamate
