Intravenous anesthetics 4 Flashcards
Rank each benzodiazepine according to its elimination half-life
midazolam, lorazepam, diazepam
What is the mechanism of action of midazolam?
GABA-A agonist
What is the onset of action of midazolam?
30-60 seconds
What is the duration of action of midazolam?
20-60 minutes
What is the clearance of midazolam?
liver
What is the active metabolite of midazolam?
1-hydroxymidazolam
What is the IV & PO sedation dose of midazolam?
IV: 0.01-0.1 mg/kg
PO: 0.5-1 mg/kg
What are the respiratory effects of midazolam?
minimal but synergistic respiratory depression when combined with other sedatives
What are the CV effects of midazolam?
minimal
What are the CNS effects of midazolam?
anterograde amnesia, anticonvulsant properties
anxiolysis
antispasmodic effects
no analgesia
What is remimazaolam indicated for?
induction & maintenance for adults undergoing procedural sedation lasting 30 minutes or less (e.g. endoscopy, bronchosocpy)
Patients with ______ are more sensitive to the respiratory depressant effects of midazolam.
COPD
What is the IV induction dose of midazolam?
0.1-0.4 mg/kg
What respiratory & CV effects does the induction dose of midazolam have?
decreased BP & SVR
respiratory depression
How does midazolam affect EEG?
cannot produce isoelectric EEG (propofol and barbiturates can)
How does midazolam cause relaxation?
spinally mediated skeletal muscle relaxation (antispasmodic-useful for patient with cerebral palsy)
Diazepam undergoes _____
enterophepatic recirculation, which explains why it remains in the body for such a long time
Diazepam can be used as an
anticonvulsant and as a preventative measure against emergence deilirum
antispasmodic agent
Lorazepam’s amnestic action lasts up to
six hours
Lorazepam has a _______ onset.
slow onset which limits its useful as an anticonvulsant
What is the relative potency (greatest to least) of the benzodiazepines?
lorazepam>midazolam>diazepam
Do any of our anesthetic drugs provide retrograde amnesia?
NO- benzodiazepines do provide anterograde amnesia
Propylene glycol is added to diazepam and lorazepam to enhance water solubility which can cause
venous irritation
Can midazolam cross the blood-brain barrier?
yes
Midazolam has a ______ which gives it hydrophilic and liphophilic properties.
imidazole
The adult induction dose of remimazolam is
5 mg IV over 1 minute (can reduce to 2.5-5 mg for sicker patients)
maintenance for procedural sedation: may administer 2.5 mg IV over 15 seconds with 2 minutes between each dose
Peak sedation for remimazolam occurs
3-3.5 minutes after administration
After reconstitution of remimazolam, the single-use vial must be discarded if
not used within 8 hours
Remimazolam is rapidly metabolized by
non-specific plasma esterases
Although it undergoes organ-independent elimination, patients with severe hepatic dysfunction receiving remimazolam
should recieve a doze reduction
Compared to midazolam, remimazolam benefits include
faster onset of action
deeper sedation
faster recovery
Compared to propofol, remimazolam is associated with
less respiratory depression
better degree of cardiopulmonary stability
Remimazolam is contraindicated in patients with a history of
severe hypersensitivity reaction to Dextran 40
Can remimazolam be reversed with flumazenil?
yes
A patient is experiencing a prolonged recovery from midazolam sedation. What is the initial dose of flumazenil?
0.2 mg
What is the mechanism of action of flumazenil?
A competitive antagonist of the GABA-A receptor
Why is flumazenil used?
to reduce the sedative effects of benzodiazepines
What is the repeat dose of flumazenil?
0.1 mg may be titrated in 1 minute intervals
Side effects of flumazenil include
seizures in benzodiazepine-dependent patients
What is an important property of flumazenil?
it has a short duration so repeated doses may be needed to prevent re-sedation
What is the duration of action of flumazenil?
30-60 minutes
Post-operative benzodiazepine reversal with flumazenil does NOT
increase SNS tone, anxiety or neuroendocrine evidence of stress
Flumazenil tends to reverse the _____ effects more than the ______ effects of benzodiazepines
sedative effects; amnestic effects
