Sedatives/Hypnotics Flashcards
Define sedatives
A drug that induces calm or sleep
Define hynotics
A drug that induces hypnosis or sleep
What does having a high CBF/CMRO2 mean?
Awake/Active
What does having a low CBF/CRMO2 mean?
Less awake/active
On the EEG wires define what the Z leads are, where the odd #’s go, where the even numbers go, and what T, F, P, & O mean.
Z leads - the reference point
Odd numbers - left side
Even numbers - right side
T- Temporal
F- Frontal
P - Parietal
O- Occipital
What is the BIS machine? When did it come out?
A machine that took all the info & leads from the EEG wires & combined them into 1 waveform.
Developed in 1996
Is a patient with a BIS < 58 consious?
No; also no change in HR, BP.
If the BIS <65 what happens? At what percent does this happen?
The patient has less than a 5% chance of returning to consciousness within 50 seconds. Have a least a minute to get the patient deeper before they wake up and move.
What is SQI?
Signal Quality Index. How much or little interference.
Define EMG. Do we want to see this?
Muscle tension detection. No want to see zero EMG.
If things are going well what should we see for the EEG on the BIS?
Should be fairly flat
Define SR.
Suppression Ratio - tells us how many times in the last 20-30 seconds the BIS has been Zero. Tells us how many times the EEG was flat. Don’t want to see this climb.
What do you want to see for the SR? How does this differ in brain-dead patients?
Flat essentially.
Will have a high suppression ratio - because there is zero activity.
What range on the BIS is the patient awake?
98-100
What number on the BIS correlates with patient having eyes closed/quiet/dreaming?
85-90
What number on the BIS appears with GA?
40-60
If the patient has a BIS > 60 what are they at risk for?
MOVING
At what range on the BIS can the patient self extubate?
70-80
What does a BIS reading of 40 indicate?
Too deep, wasting our drugs, gave too much
What are some benefits of using benzos?
Sedation
Anxiolytics
Anticonvulsants
What kind of amnesia do benzo’s cause? (Think versed)
Anterograde
Why are benzos better than barbs?
Less tolerance
Less addiction
Less potential for abuse
Few and less serious side effects
Do not induce hepatic microsomal enzymes
What is the benzo of choice for the perioperative period?
Midazolam (Versed)
What is the benzo of choice for the post-op period?
Diazepam or Lorazepam
What drug is replacing Lorazepam during the post-op period? What are its side effects?
Dexmedetomidine. Causes bradycardia
What is the primary MOA of benzos?
Facilitates the action of GABA at the GABAa chloride ionophore. They are an allosteric activator. They bind to the benzo receptors, which help GABA bind to its receptor better.
What does the alpha 1 do? Is it the most abundant type? What parts of the brain
Sedative, amnestic, anticonvulsant.
Yes
Cerebral cortex, cerebellar cortex, thalamus
What does the alpha 2 do? Its location in the brain?
Anxiolytic
Skeletal muscle
Hippocampus and amygdala
Where are GABAa receptors primarily?
CNS
What other medications bind to GABAa?
Barbiturates
Etomidate
Propofol
Alcohol
What diseases/issues cause decreased albumin levels? What effect does this have on benzos?
Cirrhosis, burns, elderly, malnutrition
Increases the free drug; more crosses the BBB & causes increased effects.
Which drug will cause an isoelectric state on the EEG? Which drug will not cause an isoelectric state on the EEG?
Diazepam
Versed
At what pH is versed’s ring open and it is water soluble and in the protonated form?
<3.5
At what pH does the versed ring close and it becomes lipid soluble?
> 4.0
Define versed’s onset, peak effect, E 1/2 time, & Vd
Onset 1-2 mins
Peak effect - 5 mins
E 1/2 time - 2 hrs
Vd - 1 to 1.5 L/kg
How is versed metabolized?
CYP3A4
Active metabolites conjugated and cleared by kidneys
Name the active metabolite of versed mentioned in class. How potent is it?
1-hydroxymidazolam. 1/2 the activity of the versed
What drugs can cause inhibition of the CYP450s?
Cemetidine (Tagament -PPI)
Erythromycin
CCBs
Antifungals
Fentanyl
How much faster is versed cleared compared to lorazepam? Diazepam?
5x faster than lorazepam
10x faster than diazepam
What benzo do you use for induction if the patient has a neuro pathology?
versed
How is valium prepared? Why is it prepared this way?
Dissolved in organic solvents have to use propylene glycol (which hurts during injection). Valium is insoluble in H2O.
Describe the pharmacokinetics of valium
Onset 1-5 mins
E 1/2 time 20-40 mins
Similar Vd to versed
Dissociates from GABAa faster than ativan
Uses the CYP3A pathway. Has 2 active metabolites
Name the 2 active metabolites of diazepam
Desmethyldiazepam - 48 to 96hrs - nearly as potent as diazepam
Oxazepam
Diazepam is a decent choice for what in patients that have this condition?
Anxiolysis/muscle relaxation with COPD patients
How much do you decrease diazepam dose in elderly, liver disease, & presence of opioids? Why do you reduce the dose?
25-50%
Because of active metabolites
What drug is great for post-op sedation?
Ativan
What drug’s metabolite does ativan resemble?
Oxazepam a metabolite of diazepam
What drug is a more potent sedative than midazolam & diazepam?
ativan
Is ativan soluble in water? What solvent does it require?
No, needs polyethylene glycol. That’s why it burns
What benzo is the slowest to end the CNS
ativan
Describe peak effect & at what dose, E 1/2 time, & clearance of ativan
Peak effect is 20-30mins with IV dose of 1-4mg
E 1/2 time is 14 hours
Not entirely dependent on hepatic enzymes
What is the antidote for benzos? How is it dosed? How long until you see reversal effects? How long does it last?
Flumazenil (Romazicon)
0.2mg IV & titrate to consciousness
Repeat 0.1mg every 1 minute to 1mg total
Reversal within 2 mins
Duration is 30-60 mins
