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What are 5 common effects of benzos??
- 1. anxiolysis
- 2. sedation
- 3. anticonvulsant actions
- 4. spinal cord mediated skeletal muscle relaxation (not enough relaxation--still need NMB)
- 5. anterograde amnesia
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What is the MOA of Barbs??
they do not activate the receptor but they enhance the affinity of the receptor to GABA to resist excitation
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What are the side effects of Benzos in general??
- fatigue
- drowsiness
- anterograde amnesia
- respiratory depression possible so avoid in patients with COPD
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What effect lasts longer with benzos? amnestic or sedative??
amnestic
ex. you may explain something to a patient post op...they may be awake and respond appropriately but they may not remember what you said...therefore you should wait about 30 mins post op before trying to teach a patient.
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How should you treat an overdose of a benzo??
- assess airway
- vent support if needed
- NG with activated charcoal --suction patient
- Give Flumazenil -- a competitive antagonist (you may have to repeat the dose several times...the benzo given can last longer in the body system than the reversal drug does)
MOST IMPORTANT THING WITH GIVING BENZOS...MAINTAIN AIRWAY!
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What should you be concerned with when using Flumazenil as a reversal??
giving the drug can cause withdrawal seizures in patients who are dependent on benzos.
dependent meaning those patients who have taken xanax for the last 30 years.
when you give Romazicon....the last 30 years of xanax is reversed.
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What is the preop dosing and time frame if you plan to give a patient Diazepam??
5 to 10 mg po 1 hour before procedure
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What is the induction dose for diazepam??
0.1-0.2mg/kg IV.. this is a last resort..typically use VERSED
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what is the dose of diazepam given for seizures??
5-10mg IV every 5 mins
for a total of 30mg
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What would be the dosing on Diazepam if you want to perform basal sedation??
give increments of 2.5 mg until patient falls into a light sleep
may take 5-30 mg for this type of sedation depending on the patient
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With Diazepam you want to keep a close eye on your patient after surgery...why is this??
Diazepam has two active metabolites. one of these metabolites is metabolized slower. therefore the patient can have episodes of RESLEEPINESS 6-8 hours after the med is given. therefore you want to keep these patients in the hospital to watch them!
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What drug should you avoid giving with Diazepam and why??
Tagament or Cimetidine
bc it inhibits P450 enzymes prolonging the effect of diazepam
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What drug do you give postoperatively if you have paradoxical vocal cord motion post extubation???
VERSED 1mg
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What drug is an active metabolite of diazepam that is often used in the treatment of DTs??
oxazepam
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Which benzo is... more potent than valium or versed, has a prolonged onset and longer elimination half-time??
Lorazepam
bc of its longer onset and elimination half time is it not used in anesthesia as a preop med
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Which benzo is mostly used for anxiety purposes??
Alprazolam
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Which benzo is used to treat seizures??
clonazepam
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Name 3 benzos used for sleep...
- 1. flurazepam
- 2. temazepam
- 3. triazolam
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What is Flumazenil and what is it's other name??
Romazicon
it is a selective competitive antagonist of benzos
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What is the duration of action of Flumazenil??
1-2 hours
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How does Flumazenil work???
It competitively inhibits the GABA
reverses benzos
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Why do you frequently have to redose Flumazenil???
it is metabolized faster than benzos so you may need more Flumazenil to block GABA
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what is the typical dose for Flumazenil??
0.1mg IV
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Where does Etomidate work??
causes depression at the Reticular Activating System
mimics gaba
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What is Etomidate dissolved in??
Propylene Glycol
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Why is it that Etomidate causes pain on injection??
due to the ingredient Propylene Glycol
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Name some characteristics of Etomidate.
Why would you give this drug over the other induction drugs??
offers cardiac stability bc it has a wider margin of safety than Propofol of STP (can use this if pt has a decreased EF or severe cardiac issues)
Will decrease ICP will maintain CPP
good for surgery bc patients wake up quickly
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What are some negatives/side effects of Etomidate??
- pain on injection
- adrenal suppression
- myoclonia
- post op n/v
- no analgesic properties
- has been associated with seizures
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How long is adrenocortical function decreased after even one dose to etomidate and why is this???
can be depressed for 5-8 hours
occurs bc etomidate inhibits enzyme 11-B hydroxylase which is responsible for both mineralcorticoids and cortioosteroids
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How does etomidate effects the lungs/ventilation???
It depresses ventilation less than the other drugs.
Will decrease TV and increase RR but this only lasts for 3-5 mins. The body compensates easily.
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Which drug would you chose to give if you still want the patient to spontaneous ventilate and if you want to prevent apnea??
Etomidate
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What is Ketamine??
a phencyclidine derivative
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What is the biggest complication for using Ketamine??
dissociative anesthesia (dissociation between the thalamocoritical systems and the limbic systems)
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What are side effects of Ketamine??
- hallicunations
- increased HR,BP,CO due to SNS effects
- increased secretions
- emergence phenomenon
- nystagmus
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What is Ketamine's MOA?
binds noncompetively to NMDA receptor, inhibits the action of NMDA receptor by glutamate and increases the effect of GABA
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Which drug is good of PO or IV drug abusers??
Ketamine
bc it works on different receptors so patients will not build up a tolerance to this drug
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What are diagnoses that make Ketamine an idea induction drug??
- shock
- cardiac tamponade
- significant hypovolemia
this drug will increase CO!!
- also good for burns/painful dressing changes
- bronchospasm
- hot spots in C sections
- good for inadequate regional techniques
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How does Ketamine effect the Respiratory System???
- bronchodilation *so good for asthma patients
- mantains laryngeal reflexes and skeletal muscles tone
- maintains respiratory drive
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Droperidol is typically used to treat...
N/V
however..try zofran and phenergan first
blocks dopamine in the medualla
it is also used to treat pruritis associated with opioid administration
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What is the main concern with Droperidol administration???
- prolonged QT interval with excessive doses
- risk for Torsades
must be on a 12 lead for 2-3 post dose no matter what the size of the dose is
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What class of drugs is precedex??
nonselective alpha 2 agonist
same class as clonidine
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Precedex infusion can not exceed ....??
24 hours
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what is the DOC in awake fiberoptic intubations?? why??
Precedex
- bc it does not depress the ventilatory drive
- so patients can spontaneously breath but remain calm
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how do low and high doses of precedex affect the BP??
- low does will decrease the BP
- but high doses will increase the BP
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What is precedex??
an isopropylphenol that is given IV as a 1% solution in an aqueous solution of 10% soybean oil
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What is different about the AstraZeneca brand of propofol??
contains EDTA to retard bacterial growth
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What are contraindications to propofol?
- soy or egg allergy
- pregnancy
- dx of cardiomyopathy or hypovolemia
- dx of lipid metabolism such as diabetic, hyperlipidemia, pancreatitis, hyperlipoproteinemia
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For TIVA what is the dose range for Propofol??
100-300mcg/kg/min
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What are some benefits of propofol??
- antiemetic effects
- antipuritic effects
- anticonvulsant activity
- attenuation of bronchooconstriction
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How does propofol effect the respiratory system??
- depression of ventilation
- bronchodilation
- decrease wheezing
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How does propofol effect the heart???
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How does propofol effect the CNS?
- decreases ICP
- decreases CBF
- autoregulation is not effected by med
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propofol infusion syndrome
- occurs with high doses of propofol
- -infusions > 4 mg/kg/hr
- 1 in every 270 patients
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what are the manifestations of propofol infusion syndrome
- cardiac failure
- rhabdomyosis
- severe metabolic acidosis
- death
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bradycardia related death and propofol
- profound bradycardia and asytole after administration of propofol
- -reported in both adults and children
- -propofol weakens response to atropine.
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difference between diprivan and propofol is mainly
- pH biggest difference
- diprivan pH=7-8.5
- propofol pH 4.5-6.4
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MOA of propofol
- asserts its sedative hypnotic effects on GABA
- -increases trans-membrane Cl which hyperpolarizes the post synaptic cell membrane and functional inhibiting of the post synaptic neuron
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propofol clearance and pharmokinectics
- extra hepatic clearance (pulmonary uptake, first pass elimination, renal excretion)
- clearance exceeds haptic blood flow which emphasizes tissue uptake especially into the lungs
- -considered to be hepatic and extra hepatic with no evidence of impaired clearance with cirrhosis
*****extra hepatic elimination of propofol occurs during anhepatic phase of liver transplantation
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