Anesthetics/Analgesics Flashcards
What inhaled anesthetic has the fastest induction rate?
Nitrous Oxide N2O
What inhaled anesthetic drug has a medium rate of onset and recovery, is pungent, and is declining in use?
Isoflurane
What inhaled anesthetic is used in combination with other agents?
Nitrous Oxide
What inhaled anesthetic drug has poor induction, rapid recovery, is pungent, and is used in outpatient care?
Desflurane
What inhaled anesthetic has the highest liver metabolism?
Sevoflurane (2-5)
What inhaled anesthetic drugs should you avoid in people with bronchospams?
pungent agents
Isoflurane and Desflurane
Balanced Anesthesia is…
combination of inhaled and IV
Oral or parenteral sedatives + local sedatives ares ____ anesthesia
Monitored
Alleviation of anxiety and pain + altered levels of consciousness produced by small doses is known as…
Conscious sedation
Light state of anesthesia used in the ICU is known as…
Deep Sedation
Analgesia = lack of pain and subsequent amnesia is seen in what stage of anesthesia?
Stage I
Stage II of anesthesia is known as…
Excitement
Delirium, combative behavior, increased BP, increased RR is what stage of anesthesia?
Stage 2 - Excitement
Surgical Anesthesia is associated with…
Stage III = regular respiration, skeletal muscle relaxation, decreased eye reflexes and movements, fixed pupils, AND loss of motor and autonomic responses to pain
What is required before beginning surgery on a patient to ensure no pain is felt?
Reaching Stage III of anesthesia which results in loss of motor and autonomic responses to pain
Which stage of anesthesia is involved with depression of respiratory and vasomotor centers?
Stage IV = Medullary Paralysis
Can lead to death without intubation
What type of anesthetics end in -flurane and what is the outlier of that group?
General inhalational anesthetics
Nitrous Oxide
Increased ventalitory depth and rate cause…
shorter induction time
increased uptake from lungs…
increased rate of induction
lower solubility = higher arterial pressure which causes…
faster induction since less of it is dissolved in blood
Seen in blood/gas partitioning coefficients
Which type of tissue accumulates anesthetics the slowest?
adipose tissue and muscle
What is the Meyer & Overton Rule?
higher lipid solubility = more potent
What is MAC?
When 50% of patients are rendered immobile.
So EC50
What inhaled anesthetic has the highest MAC
nitrous oxide (100%) so it’s used in combination
What is the major route of clearance of inhaled anesthetics?
lungs
What are the 4 steps in the MOA of an anesthetic?
- DRG neurons
- Frontal cortex - sedation
- Thalamus- hypnosis/loss of consciousness
- Ventral horn neurons- loss of motor function/immobile
What is the most sensitive area of neurons that is affected by anesthetics first?
Dorsal root ganglia neurons
What does the thalamus step cause in a patient…
loss of consciousness
What are the possible MOA for inhaled anesthetics in terms of activating?
Activating GABA-A receptors and glycine receptors (inhibitory)
Activating K+ channels –> hyperpolarization
What are the possible MOA for inhaled anesthetics in terms of inhibition?
Inhibiting glutamatergic ionotropic receptors and neuronal nicotinic AChR
What is the MOA of nitrous oxide?
Blocks the NMDA-receptor
like ketamine
Is nitrous oxide a weak or strong analgesic?
Strong pain reliever
Malignant hyperthermia is caused by…
mutations in ryanodine receptors –> sensitization to anesthetics –> release massive amounts of Ca2+ into cytosol –> trigger massive contraction
What is mutated in malignant hyperthermia?
Ryanodine receptor mutations
What disorder is AD and characterized by tachycardia, hypertension, severe muscle rigidity, hyperthermia, hyperkalemia, and acidosis?
Malignant Hyperthermia
How do you treat Malignant Hyperthermia?
Dantrolene
What is the MOA of dantrolene?
blocks Ca2+ release from ryanodine receptor activation of Sarcoplasmic Reticulum
What drug can diffuse into cavities and cause (for example) pneumothorax?
Nitrous Oxide
How much liver metabolism is associated with nitrous oxide?
None.
Balanced anesthesia is a combo of inhaled and IV drugs. IV drugs include…
Premedication
Induction
Intubation
Maintenance
For balanced anesthesia, what is the premedication?
Midazolam (IV benzodiazepine)
What induction IV drugs are used in balanced anesthesia?
Fentanyl (opioid)
Propofol (anesthetic)
Curare-like NM blocker (pancuronium)
Is intubation of the trachea required in balanced anesthesia?
Yes.
What maintenance drug is used in balanced anesthesia?
Inhalational- sevoflurane + nitrous oxide combo
What is TIVA?
Total Intravenous Anesthesia
What drugs are used in TIVA?
Premedication- midazolam
Induction- remifentanil or propofol
Trachael intubation
Maintenance- remifentanil and propofol (instead of inhaled drugs)
What drugs are used as adjuncts prior to induction?
Premedication - benzodiazepines
What drug is used for sedation procedures that do not require general anesthesia?
Benzodiazepines
What class of drug is Fentanyl?
An opioid
What are 3 uses for Opioids like fentanyl?
induction & maintenance of TIVA
epidural anesthesia with local
ICU- conscious and deep sedation
What drug has chest wall laryngeal rigidity and impaired ventilation?
Opioids like fentanyl, sufentanil, and remifentanil
What drug is a lipophilic agent that rapidly enters and depresses CNS, is short-acting?
Barbiturate anesthetics like thiopental
Thiopental is…
a barbiturate anesthetic used in induction of anesthesia and deep sedation
Is the barbiturate class good analgesics?
No, but they decrease cerebral metabolism and flow which is good with head swelling patients
Propofol is..
the most commonly used agent for induction and maintenance
What is the MOA of propofol?
Potentiates/activates the GABA-A receptors
What drug has rapid onset and recovery which is why it’s common in day surgeries, conscious sedation, and radiology?
Propofol
What drug is a PCP analog?
Ketamine
What is the MOA of Ketamine?
blocking of NMDA receptor
Is ketamine a good analgesic?
Yes.
What drug causes dissociateive anesthesia, catatonia, amnesia, analgesia, no loss of consciousness?
Ketamine
What drug is used commonly with kids and short procedures of adults?
Ketamine
What is the ONLY IV drug that induces cardiovascular stimulation causes increased HR and CO?
Ketamine
What drug is associated with postoperative hallucinations?
Ketamine
What is the MOA of Etomidate?
Potentiation of GABA-A receptors
What drug is used in patients at risk of hypotension?
Etomidate because it causes minimal cardiovascular depression
What drug is used for short-term sedation of intubated and ventilated ICU patients or during regional anesthesia?
Dexmetomidine
What is the MOA of Dexmetomidine?
a2- adrenergic receptor agonist –> analgesia and hypnosis
Hypnosis by Dexmetomidine is caused by activation of a2-adrenergic receptors in…
locus coeruleus (involved in endogenous sleep states)
What is the MOA of hypnosis by Dexmetomidine?
a2- adrenergic receptor activation in Locus ceruleus –> decreases NE –> release of GABA (inhibitory) from the ventrolateral preoptic nucleus (VPN) –> prevents release of histamine from tuberomamillary nucleus –> NO arousal –> sleep
What are the good analgesics?
Nitrous oxide
Fentanyl
Ketamine
Dexmetomidine
What IV drugs have less affects on respiratory function?
Etomidate, Ketamine, and Dexmetomidine
What drug is an antiemetic?
Propofol
What drugs have increased cerebral blood flow and intracranial pressure? And should be watched with head trauma patients.
Volatiles, Nitrous oxide, Fentanyl, Ketamine
What drugs have decreased cerebral flow and intracranial pressure? Should be used in head trauma patients.
Thiopental, Propofol, Etomidate, and Dexmetomidine
What drug should you watch for in liver failure patients?
Fentanyl
What drug would a heroin addict not respond to?
Fentanyl
What are the two classes of local anesthetics?
esters (one I) and amides (two Is)
What enzymes hydrolyze esters?
plasma esterases
Esters end in -caine and have ___ I’s
1 I
Lipophilic esters are…
More potent and longer lasting
What drugs have longer duration than esters and are metabolized in the liver?
Amides (two Is)
Two a’s = long lasting
Amides also end in -caine but have __ I’s
2
What is the MOA of local anesthetics?
OPEN channel blocks of voltage-gated SODIUM channels
They block from the inside when channels are open –> decreased AP propagation –> conduction failure
What molecule crosses the membrane in local anesthetic MOA?
uncharged base
What molecule blocks the channel from the inside?
The cationic BH+
Explain the H-H application in acidic environments?
Lower pH –> more H+ –> push to BH+ side of equation –> less B to go across membrane –> less blocking from inside –> more pain
What molecule can be used in combination with local anesthetics to ensure B crossing membrane?
Bicarbonate
Local anesthetics work better on what types of fibers…
smaller nerve fibers and myelinated fibers
Local anesthetics can selectively block pain fibers because…
they fire rapidly
Fibers located where are blocked sooner by local anesthetics?
The periphery of thick nerve bundles because they are exposed before
What is the order of blockade by local anesthetics?
pain fibers –> other sensations –> motor function
What fibers are lease sensitive to local anesthetics?
aA fibers- proprioception and motor
Why do we give an injection of epinephrine with local anesthetics?
Causes vasoconstriction via activation of a1-adrenergic receptors –> decreases removal of local anesthetic –> increases duration and effect
Also activates presynaptic a2-adrenergic receptors –> decrease release of pain mediators such as Substance P
Local bleed control
What drug helps local bleed control?
Epinephrine
What receptor does epinephrine block to decrease release of pan mediators such as Substance P?
a2-adrenergic
What local anesthetic is used topically in cases of pruritus?
Dibucaine
Amide, short-lasting
What are the adverse affects of dibucaine?
absorbed rapidly –> toxicity
For wound suturing and biopsies, you use what local anesthetic?
Injection (infiltration) without considering cutaneous nerves or deep tissue structures
What are adverse affects of infiltration local anesthetics?
Injection can cause inadvertent intravascular injection
prevent by aspirating
IV Lidocaine can be used as…
an anti-arhythmic agent for ventricular arrhythmias
Allergies are commonly associated with which local anesthetic group?
Esters
What do you NOT give to patients with limited collateral circulation (toes, fingers, nose, ears, etc)
Epinephrine
Cardiovascular collapse is associated with high volumes of bupivacaine. Instead use the lower affinity…
Levobupivacaine and ropivacaine
Lipid emulsion acts as a “sink” for anesthetics which you can reverse by…
lipid resuscitation - saving the patient
What drugs are used to reverse opioid effects? Antagonists of opioids?
Naloxone and Naltrexone
end in -xone
Strong analgesics include:
Morphine, oxycodone, fentanyl, methadone, meperidine
Partial analgesics include:
codeine and hydrocodone
Buprenorphine is a…
mixed-opioid agonist-antagonist
What opioid is also used for acute pulmonary edema?
Morphine
What opioid is also used for antitiussive?
dextromethorphan
What opioid is also used for anti diarrhea?
diphenoxylate and loperamide
What opioid is also used for shivering?
meperidine
What opioid is also used for adjuncts to anesthesia?
fentanyl (regionally)
Sedative hypnotics with opioids cause what adverse effect…
increased respiratory depression (CNS depression)
intubation required
Antipsychotic tranquilizers used with opioids cause…
increased sedation and cardiovascular affects
Monoamine oxidase inhibitors used with opioids cause…
hyperpyrexic coma and hypertension
Endorphins have the highest opioid receptor affinity to u (mu) which are located in…
brain, brainstem, spinal cord = CNS
What analgesics have the highest 1st pass elimination upon oral admin?
morphine
The best route of admin for oxycodone is…
oral
The best route of admin for fentanyl is…
transdermal
Since morphine has high 1st pass effect, you can give it…
parenterally (elsewhere)
Low oral:parenteral ratio
High oral:parenteral ratio is seen in…
methadone
What are the metabolites of morphine and what do they do?
M3G (90%) and M6G
Accumulation can lead to CNS effects
morphine is eliminated by what…
kidneys
Fentanyl is metabolized by…
hepatic oxidative metabolism via P450 system
CYP3A4
Codeine also has a high oral: parenteral ratio because demethylated it is…
morphine
As you take more opioids, you build no tolerance to…
miosis, constipation, and convulsions
As you take more opioids, you build tolerance to…
nausea and vomiting cough suppression respiratory depression anti-diuresis etc.
Opioids can affect the heart by causing…
brachycardia (slow heart action)
What opioid is best for chronic and severe pain… not sharp, intermittent pain?
Morphine
What opioid is given via transdermal patch over long periods?
Fentanyl
What opioid is given in the mucosa of the mouth for short, breakthrough pain?
Fentanyl
What opioid is is used in maintenance in rehabilitation programs because withdrawal symptoms are less severe?
Methadone
What drug has less severe respiratory depression, constipation, biliary colic, and urinary retention? In addition to strong anti-muscarinic effects and tachycardia?
Meperidine
What drug combination is used with heroin addicts?
Buprenorphine and naloxone
