Anesthetics Flashcards
What is monitored anesthesia care?
Using sedatives and other agents, but the dose is low enough that the patient remains responsive and able to breath without assistance. We use this for simple procedures and minor surgery. MAC generally refers to IV sedation.
What is the main difference between MAC and GA?
Patients in GA no longer respond to stimuli
Define minimal, moderate, and deep sedation, and general anesthesia
Minimal Sedation (Anxiolysis)- Pt responds normally to verbal commands. Cognitive function and coordination may be impaired. Vent and CV function unaffected.
Moderate Sedation (Conscious sedation)- responds purposefully to verbal commands alone or with light tactile stimulation. Airway and ventilation are fine. CV usually fine.
Deep- Not easily aroused. Responds purposefully to repeated/painful stimuli. Ventilation and airway may be impaired. CV usually fine.
GA- Not arousable even by painful stimuli. Needs assistance with patent airway, may need PPV. CV may be impaired.
Effects of general anesthesia
No sensory perception
Loss of consciousness
No recall of events
Immobility
Others include muscle relaxation (although you don’t NEED muscle relaxants), suppression of the ANS, analgesia, and anxiolysis.
What is the only anesthetic that has analgesic properties?
Ketamine. Our other anesthetics just cause loss of consciousness.
General induction sequence
Pre-op meds (anxiolytic, antibiotic, etc)
Induction agent
Paralytic
Maintenance agent
Opoids
Antiemetics
Reversal agents (reversal of the paralytic)
Why do we need to give antiemetics?
Because the opioids and anesthetics can cause nausea
5 effects of benzodiazepines
ASAAM
1) Anxiolysis
2) Sedation
3) Antegrade amnesia
4) Anticonvulsant
5) Muscle relaxation (at the spinal level)
Prototype for benzos
Diazepam (Valium)
Midazolam (Versed) is an example of this class of drugs)
Benzos
How do benzodiazepines work?
Potentiating the binding of GABA to GABAa receptors and increases the potency of GABA x 3.
Causes Cl- influx, hyperpolarizing the cell and decreasing its excitability
When would benzos drop your BP?
When used in large doses for induction (due to a decrease in SVR), especially with hypovolemia. Also may decrease because the pt was anxious before and is now more relaxed.
When are benzos contraindicated?
Pregnancy
What do opioids bind to?
On Mu receptors which can be located on either the pre or post-synaptic membranes
At what anatomical locations do opioids work?
In the brainstem, spinal cord, and peripheral tissues
Opioids result in decreased release of this NT
Substance P
Why should we try to avoid a benzo/opioid cocktail pre-operatively?
They have a synergistic effect on ventilation
What is the benefit of using opioids for general anesthesia?
It doesn’t drop BP (although it will cause bradycardia!)
How much fentanyl would be needed to induce GA?
50-100mcg/kg
This class of drugs are the classic induction agents
Barbiturates. Because the end result is depressing the reticular activating system (causing sleep).
Which are more effective as anticonvulsants, benzos or barbiturates?
Barbiturates
Which class of medications, when injected arterially, will cause gangrene and nerve damage?
Barbiturates
What can cause enzyme induction?
Smoking, ETOH, and barbiturates.
What barbiturate is the most potent enzyme inducer?
Phenobarbital
What’s the deal with barbiturate allergies?
It’s very rare (1:30,000), but highly fatal
Barbiturates increase the metabolism of these drugs
Oral anticoagulants, phenytoin, TCAs, corticosteroids, and Vitamin K
Barbiturates should be avoided in patients with
Porphyria.
Barbs cause rapid heme production through the stimulation of the enzyme D-aminolevulinic acid synthetase. People with porphyria have shitty heme. So if you give benzos to these people, they will have a shit ton of shitty heme.
Do barbiturates cross the placenta?
Yes.
Barbiturates stimulate this enzyme responsible for heme production
D-aminolevulinic acid synthetase
What is included in the base of propofol?
Egg, soy, and glycerol
Bronchoconstriction is often related to what?
Patient not being deep enough. Asthmatics are at an even higher risk of this if they are not deep enough. You want asthmatics to be very deep because they are at high risk of bronchoconstriction when stimulated.
Can propofol be given to those with egg allergies?
Yes
This medication attaches to the B1 subunit of the GABAa receptor
Propofol
Succinylcholine binds to what type of receptors?
Nicotinic ACh receptors
Succinylcholine is often replaced with
Rocuronium
How can we reduce myalgias with succ?
Give a small dose of a non-depolarizing agent first, and then give the succ
If giving succ to kids, what should you also give them and why?
Give atropine. Succ blocks ACh receptors, which can cause profound bradycardia in kids.
This medication is a POTENT trigger of malignant hyperthermia
Succinylcholine. Isoflurane can also trigger MH.
Succ should be avoided in
Patients with atypical acetylcholinesterase. Remember this is familial, so if the patient describes a family member not waking up after surgery, etc., then don’t draw this up as an emergency medication.
Patients with these diseases are at higher risk for hyperkalemia when given succ
Burns, trauma, nerve damage, neuromuscular diseases, and renal failure. `
Prototype for the non-depolarizing muscle relaxants
Vecuronium
Structure of vecuronium
Monoquarternary aminosteroid
What receptors does vecuronium work on?
Pre and post-synaptic nACh receptors
For what patients will vecuronium not work?
Burn patients
Things to look out for with vecuronium
Residual NM blockage and increased likelihood of recall
How are inhalational anesthetics eliminated?
Via the lungs. We can alter elimination by varying the RR. Liver and kidney disease won’t affect metabolism or elimination.
What is usually the only inhalational anesthetic used for induction?
Sevoflurane
Do inhalational anesthetics act as a bronchodilator or constrictor?
Bronchodilator
What is the MAC of an anesthetic?
The alveolar concentration of an inhalational agent at which 50% of patient will not move to a noxious stimulus
What is the only inhalational agent we used that will not provide anesthesia by itself?
Nitrous oxide (N2O)
Local anesthetics will block APs ONLY if the Na channels are in this state
Inactivated-closed
If your patient starts having signs of local anesthetic toxicity, you should give them this
Versed (because the patient will probably have a seizure)
Local anesthetic with high risk for cardiac toxicity
Bupivicaine (can cause arrythmias, AV blocks, hypotension, and arrest)
What class of drug would you want to give to induce anesthesia in a patient with high ICP?
Barbiturates
