Sedatives/ Hypnotics Flashcards
A drug that induces calm or sleep is called a _______.
A drug that induces hypnosis is called a _________.
Sedative
Hypnotic
Both general anesthesia and sleep share similarities in that both inhibit _________ and ___________.
General anesthesia and sleep also reversibly inhibit the ________.
Thalmic
Mid-Brain Reticular Activating System (RAS)
CNS
1 in 10,000 patients will experience this in general anesthesia.
Awareness
In 1937, ___________ could be used to measure the effects of anesthesia.
EEG
In 1952, the depth of anesthesia correlates with ___________ of ether used.
Concentration or MAC
Anesthesia alters ____________ and ______________.
Cerebral Blood Flow (CBF)
Cerebral Metabolic Rate of Oxygen (CMRO2)
What was the issue with using EEG machines to measure the depth of general anesthesia?
Not practical to use so many leads and the device was large and bulky.
In 1996 the __________ was created using 1500 subjects and 5000 hours of EEG signals. It uses an algorithm and pattern to determine a patient’s depth under general anesthesia.
Bispectral Analysis
What was the BIS tested with?
Isoflurane/O2
Propofol/ Nitrous
Propofol/ Alfentanil
BIS change correlates to _____________.
What is the exception?
Patient movement.
The lower the number, the less movement
Exception: High dose narcotics have less correlation between BIS and movement
No patient with a BIS score less than _________ was conscious.
BIS scores less than ________ show that less than 5% chance of return to consciousness within 50 seconds.
58
65
What is the BIS range?
What is the ideal BIS range for someone under general anesthesia?
0 to 100
40 to 60
On the BIS monitor, what is the SQI?
EMG?
EEG?
SR?
SQI - Signal Quality Index
EMG- Electromyographic, tells you if the patient is about to move
EEG- brain activity
SR- Suppression Ratio, should be 0, how many seconds in the last minute has the EEG been flat.
Are BIS monitors 100% reliable?
No, different drugs such as ketamine and epinephrine can give the BIS monitor a falsely high reading despite the patient being adequately sedated.
Very important to look at BIS trends
What are the five main actions of BZDs?
- Anxiolytics
- Sedation
- Anterograde Amnesia (this last longer than sedative effects)
- Anticonvulsant
- Spinal Cord mediated skeletal muscle relaxation (not adequate for surgery)
What were the reasons that BZD replaced barbiturates for preop sedation?
Less tolerance was developed with BZD.
BZD had less potential for abuse.
BZD had fewer and less serious S/E.
BZD does not induce hepatic microsomal enzymes.
What are the similarities between BZD and barbituates?
Similar structure
Specific pharmacologic antagonist (flumazenil)
What is the most commonly used BZD in the perioperative period? This is also used as a preop med and for conscious sedation.
Midazolam (Versed)
Which two BZD have a greater half time than midazolam and more attractive for sedation post-op?
Diazepam (Valium)
Lorazepam (Ativan)
What is the MOA of a BZD?
The mechanism of action is GABA- mediated.
BZD binds at GABA-A Chloride Inophore receptors. This will enhance the affinity of receptors for GABA, opening chloride channels and inducing hyperpolarization.
Which receptor subunit on GABA is the most abundant?
What effect does it have?
What part of the brain does it affect?
Alpha-1
Sedative, Amnestic, Anticonvulsant
Cerebral cortex, Cerebellar cortex, thalamus
What receptor subunit on GABA exhibits anxiolytic and skeletal muscle relaxation?
What part of the brain does it affect?
Alpha-2
Hippocampus, amygdala
Name agents or drugs that can have a synergistic effect with BZD.
Barbituates
Injected Anesthetics (Propofol)
Inhaled Anesthetics
Etomidate
Alcohol
Opioids
Alpha-2 agonist (Precedex)
All these bind to the Alpha subunit on the GABA receptor
The BZD that we use in anesthesia is highly ______________ and highly (98%)________________.
What does that mean?
Lipid Soluble
Protein Bound
This means that BZD will work quickly and go away quickly.
B/c they are lipid soluble, BZD will have a large Vd, just not a large amount because they are highly protein bound
Looking at an EEG, BZD will decrease __________ activity.
Some BZD are unable to produce a _______________ state.
BZD will cause ______________ amnesia.
Alpha
Isoelectric state
Anterograde
BZD inhibits _________________. Increasing the risk of bleeding.
Platelet aggregating factors
What type of structure does a BZD have that allows rapid metabolism?
Imidazole ring
How many more times potent is midazolam compared to diazepam?
2-3x, midazolam has a greater affinity for the receptor