Anesthetic Mechanisms Flashcards
What are the drugs used in monitored anesthesia
Midazolam for premedication, then propofol for the deeper sedation
What is the mechanism of action of propofol
GABAa agonist receptors
What are the general toxicities seen with inhaled anesthetics
- Nausea and vomiting
- Malignant hyperthermia if used with succinyl CoA
What is deep sedation
Decreased consciousness, loss of protective reflexes, no patent airway, lock of verbal responsiveness
What are the toxicity seen in the CV with local anesthetics
Block cardiac sodium channels and decrease the amount of excitability, conduction, contractility, arteriole dilation, and hypotension
What is conscious sedation
Used by dentists where the patient is awake and responsive
What is the method of epidural anesthesia
Injection into the epideral space to create a large area
What is the method of block anesthesia
Injection into the major nerve trunks, so results in a region distal to the site of injection (such as brachial plexus)
What are the toxicities of local anesthesia at low concentrations
- Sleepiness
- light headed
- visual and auditory disruptions
- restlessness
What are the characteristics of an anesthetic agent that high low blood solubility
Reaches high arterial pressure slowly, so it reaches equilibrium slowly, resulting in a slow onset of action
What is the mechanism that most general anesthetics work
- Activation of chloride channels for hyperpolarization (GABA and Glycine)
- Decreased excitatory channels activity
What is monitored anesthesia
Sedation based anesthetic technique for diagnostic and mino therapeutic surgical procedures, where premedication is given, then followed by another for deep sedation
What can be given to help control seizures and what is the mechanism
Benzodiazepine, which raising the threshold of seizure activity
What is the mechanism of action for local anesthetics
Blocks the voltage gated sodium channels, so there is no spread of the depolarization
What is the method of infiltration anesthesia
Direct injection into the tissues near peripheral nerve endings
What are the toxicities seen in high doses of local anesthetic
- Nystagmus
- Convulsions
- muscle twitching and fasciculation
What is the method of spinal anesthesia
Injection into the CSF in the lumbar space in order to produce a great area
Where are ester type agents metabolized
In the plasma by circulating enzymes
Which type of fibers are most susceptible to blockage by a local anesthetic
Type C (dorsal root and SNS) > Type B (pregang) > Type A delta
What are the characteristics of a gaseous anesthetic
High vapor pressure and low boiling point, so they are gas at room temperature
Where are amide-type anesthetics metabolized
In the liver by CYP450 and excreted in the urine
What is the mechanism of action of opioid analgesics in anesthesia
Given in combination with benzo
Where do inhaled anesthetics tend to accumulate and have an effect first
The organs receiving a higher cardiac output, such as the heart, liver, and kidneys, with the muscle tissues taking much longer
What are the characteristics of effects for an anesthetia
- Unconscious
- amnesia
- analgesia
- attenuated Autonomic responses
- immobility
What is the response in the CV to inhaled anesthetics
They decrease the mean arterial pressure in direct proportion to their alveolar concentration, but increase the right atrial pressure proportionately
What is the mechanism of action of dexmedetomidine
Alpha 2 adrenergic agonist (hypnotic like state)
What are the characteristics of an anesthetic with a low blood solubility
Reaches high arterial pressure rapidly, so there is a rapid equilibrium with the brain and subsequent onset of action
What is the mechanism of action of benzodiazepines
Increased GABAa sensitivity
What are the parameters that the efficacy of inhaled anesthetics are based on
- Concentration of anesthetic in air
- Ventilation rate
- drug solubility in the air, blood, and CNS
What is the blood:gas’s partition
Relative affinity of an anesthetic for the blood compared to the inspired gas (aka blood solubility)
What is the minimal alveolar concentration (MAC)
Amount of an anesthetic to prevent a response to a surgical incision in 50% of patients
What is the mechanism of action of ketamine
NMDA antagonist
What is the reasoning that a blood soluble anaesthetic takes longer to affect the brain
Because the gas is soluble in blood, it must fist completely saturate the blood with the gas before it can affect the brain, as opposed to insoluble, which will reach maximum saturation much quicker and therefore affect the brain much faster
How can you tell between an amide and ester local anesthetic
Amide- will have at least 2 i’s in in
Ester-Will only hav ethe I in -caine
How are inhaled anesthetics eliminated, and which are eliminated the quickest
They are eliminated via the lungs, and those that are not blood soluble result in much quicker elimination
What is the toxic effect of inhaled anesthetics on the respiratory system
Respiratory depressants (reduced response to increased CO2 levels)
What are the characteristics of volatile inhaled anesthetics
Low vapor pressure and high boiling points so they are liquid at room temperature
What is the mechanism of action of barbiturates in anesthetics
GABAa receptor agonist
What is the mechanism of action of etomidate
Enchances GABA on GABAa receptors
