General anesthesia

Question 1

What are general anesthetics used for?

Answer 1

General anesthetics are used to induce an anesthetic state in patients undergoing surgery.

Question 2

Question: What conditions make up the anesthetic state?

Answer 2

Answer: The anesthetic state includes unconsciousness, sedation, analgesia, and amnesia.

Question 3

Question: How do general anesthetics achieve their effects on the central nervous system?

Answer 3

Answer: General anesthetics depress the central nervous system by reducing action potentials, either by blocking excitatory synapses or enhancing inhibitory synapses.

Question 4

Question: What is the role of glutamate in excitatory synapses?

Answer 4

Answer: Glutamate is the main neurotransmitter in excitatory synapses and binds to NMDA receptors to initiate action potentials.

Question 5

Question: How do some general anesthetics interact with NMDA receptors?

Answer 5

Answer: Some general anesthetics work by blocking NMDA receptors.

Question 6

Question: What is the role of GABA in inhibitory synapses?

Answer 6

Answer: GABA is the inhibitory neurotransmitter that binds to postsynaptic neurons to prevent them from firing.

Question 7

Question: How do certain anesthetics affect GABA receptors?

Answer 7

Answer: GABA is the inhibitory neurotransmitter that binds to postsynaptic neurons to prevent them from firing.

Question 8

Question: How do certain anesthetics affect GABA receptors?

Answer 8

Answer: Certain anesthetics stimulate GABA receptors or increase their sensitivity to GABA.

Question 9

Question: How do parenteral anesthetics travel and act in the body?

Answer 9

Answer: They travel through the bloodstream to lipophilic tissues like the brain and spinal cord to induce the anesthetic state.

Question 9

Question: What are common parenteral anesthetics?

Answer 9

Answer: Common parenteral anesthetics include thiopental, midazolam, propofol, and etomidate.

Question 9

Question: What are the two main phases of anesthesia?

Answer 9

Answer: The two main phases are induction, where the patient enters the anesthetic state, and maintenance, where the state is prolonged as needed. emergence is when maintance anesthesia is weaned off

Question 10

Question: What are the two classes of general anesthetics based on administration?

Answer 10

Answer: General anesthetics are classified as parenteral (injected) or inhalational (inhaled).

Question 11

Question: What is a key characteristic of the onset and duration of parenteral anesthetics?

Answer 11

Answer: They generally have a rapid onset within 20-30 seconds and a short duration.

Question 12

Question: What are the primary effects and side effects of thiopental?

Answer 12

Answer: Thiopental causes cardiovascular and respiratory depression, decreases intracranial pressure, and can trigger asthma attacks due to histamine release.

Question 13

Question: What are the properties of midazolam compared to other parenteral anesthetics?

Answer 13

Answer: Midazolam has a slower onset and longer duration, causes less respiratory and cardiovascular depression, but can cause cognitive dysfunctions like amnesia.

Question 14

Question: Why is propofol preferred for outpatient surgery?

Answer 14

Answer: Propofol has a short duration, allowing for faster recovery, and doesn’t cause bronchoconstriction.

Question 15

Question: What are the notable properties and side effects of etomidate?

Answer 15

Answer: Etomidate causes less cardiovascular depression and is preferred for patients with cardiac issues but can cause adrenal suppression.

Question 16

Question: How does ketamine differ from other parenteral anesthetics?

Answer 16

Answer: Ketamine blocks NMDA receptors, has a longer duration, increases intracranial pressure and cardiac output, and is suitable for patients at risk of hypotension and asthmatics. It can also cause dissociative anesthesia and hallucinations.

Question 17

Question: What are the key characteristics of inhaled anesthetics?

Answer 17

Answer: Inhaled anesthetics have a small therapeutic window, are administered via inhalation, and are either gases or volatile liquids.

Question 18

Question: What are the main effects of nitrous oxide?

Answer 18

Answer: Nitrous oxide acts as an NMDA receptor antagonist, has rapid induction and recovery, and provides analgesia at lower concentrations. It doesn’t cause malignant hyperthermia.

Question 19

Question: What are the contraindications for using nitrous oxide?

Answer 19

Answer: Nitrous oxide is contraindicated for people with pneumothorax or bowel obstructions due to its expansion of trapped gases.

Question 19

Question: What is the “second gas effect” of nitrous oxide?

Answer 19

Answer: The “second gas effect” means that nitrous oxide lowers the therapeutic dose required for other inhaled anesthetics.

Question 20

Question: What are halogenated inhalational anesthetics and their common properties?

Answer 20

Answer: Halogenated anesthetics like halothane, enflurane, methoxyflurane, and desflurane act as NMDA receptor antagonists and GABA receptor agonists, cause cardiovascular and respiratory depression, and increase intracranial pressure.

Question 21

Question: Why is halothane no longer used in developed countries?

Answer 21

Answer: Halothane is no longer used due to its severe and sometimes fatal hepatotoxicity.

Question 22

Question: What is the main adverse effect of methoxyflurane?

Answer 22

Answer: Methoxyflurane causes nephrotoxicity.

Question 23

Question: Why is desflurane not used as an induction agent?

Answer 23

Answer: Desflurane has a pungent smell and can cause airway irritation leading to coughing.

Question 24

Question: What is the main adverse effect of enflurane?

Answer 24

Answer: Enflurane lowers the seizure threshold and is contraindicated in people with epilepsy.

Question 25

Question: What life-threatening condition can halogenated anesthetics cause?

Answer 25

Answer: Halogenated anesthetics can cause malignant hyperthermia, characterized by muscle rigidity, hyperthermia, and metabolic acidosis.

Question 26

Question: What are the pros and cons of thiopental, and what are its indications for use?

Answer 26

Answer:
Pros: Rapid onset, short duration, decreases intracranial pressure.
Cons: Causes cardiovascular depression, respiratory depression, can trigger asthma attacks.
Indications: Induction of anesthesia, short procedures like tracheal intubation, traumatic brain injury.

Question 27

Question: What are the pros and cons of midazolam, and what are its indications for use?

Answer 27

Answer:
Pros: Longer duration, less respiratory and cardiovascular depression.
Cons: Slower onset, can cause cognitive dysfunctions like amnesia and postoperative respiratory depression.
Indications: Induction of anesthesia, sedation for short procedures.

Question 28

Question: What are the pros and cons of etomidate, and what are its indications for use?

Answer 28

Answer:
Pros: Less cardiovascular depression.
Cons: Causes adrenal suppression.
Indications: Induction of anesthesia in patients with coronary artery disease, cardiomyopathy, cerebral vascular disease, or hypovolemia.

Question 29

Question: What are the pros and cons of propofol, and what are its indications for use?

Answer 29

Answer:
Pros: Short duration, fast recovery, does not cause bronchoconstriction.
Cons: Causes vasodilation, cardiovascular depression, rare propofol infusion syndrome.
Indications: Induction and maintenance of anesthesia, especially in outpatient surgery.

Question 30

Question: What are the pros and cons of ketamine, and what are its indications for use?

Answer 30

Answer:
Pros: Rapid onset, longer duration, increases blood pressure and cardiac output, suitable for asthmatics, does not cause cardiovascular depression.
Cons: Increases intracranial pressure, causes hallucinations and delusions upon waking.
Indications: Induction and maintenance of anesthesia, patients at risk of hypotension, asthmatic patients.

Question 31

Question: What are the pros and cons of nitrous oxide, and what are its indications for use?

Answer 31

Answer:
Pros: Rapid induction and recovery, analgesic effect at lower concentrations, does not cause malignant hyperthermia.
Cons: Weaker effects, diminishes the respiratory response to hypoxia, can cause expansion of trapped gases.
Indications: Dental procedures, adjunct with other inhaled anesthetics for the second gas effect.

Question 32

Question: What are the pros and cons of halothane, and what are its indications for use?

Answer 32

Answer:
Pros: Dilates airways, suitable for asthmatics.
Cons: Severe hepatotoxicity.
Indications: No longer used in developed countries due to hepatotoxicity.

Question 33

Question: What are the pros and cons of methoxyflurane, and what are its indications for use?

Answer 33

Answer:
Pros: Potent anesthetic.
Cons: Causes nephrotoxicity.
Indications: No longer widely used due to nephrotoxicity.

Question 34

Question: What are the pros and cons of desflurane, and what are its indications for use?

Answer 34

Answer:
Pros: Rapid onset and recovery.
Cons: Pungent smell, airway irritation, unsuitable for induction.
Indications: Maintenance of anesthesia.

Question 35

Question: What are the pros and cons of enflurane, and what are its indications for use?

Answer 35

Answer:
Pros: Effective anesthetic.
Cons: Lowers seizure threshold, not suitable for epileptics.
Indications: Maintenance of anesthesia (contraindicated in patients with epilepsy).

Question 36

Question: What common side effect is shared by all halogenated inhalational anesthetics, and what is the exception among inhalational anesthetics?

Answer 36

Answer:
Common Side Effect: All halogenated inhalational anesthetics can cause malignant hyperthermia.
Exception: Nitrous oxide does not cause malignant hyperthermia.