40 Questions
What is the primary use of inhalation anesthetics?
To maintain anesthesia
What determines the potency of an inhalation anesthetic?
Lipid solubility
Which of the following is an inorganic agent used in inhalation anesthesia?
Nitrous oxide
What is the MAC of nitrous oxide?
100
Which of the following factors affects the transfer of general anesthetics from the lung to the blood and then to the brain?
All of the above
How does the rate of induction of anesthesia change with an increase in anesthetic concentration in the inspired air?
It increases
Which anesthetic is 2 times more potent than enflurane?
Halothane
What determines the speed of induction of anesthesia?
Blood solubility
What is the key factor that determines the rate of absorption of inhalation anesthetics from the lungs?
Blood/gas partition coefficient
What is a common adverse effect of volatile anesthetics?
Respiratory depression
What is a unique characteristic of isoflurane?
It is minimally metabolized and eliminated unchanged in the expired air
What is the Minimum Alveolar Concentration (MAC) of isoflurane?
1.4%
What is a potential complication of using isoflurane?
Malignant hyperthermia
What is the MAC of sevoflurane?
2%
What happens to most of the sevoflurane administered to a patient?
It is eliminated unchanged in the expired air
What is a common approach to mitigating the adverse effects of volatile anesthetics?
Using them in combination with intravenous agents
What is a characteristic of etomidate's pharmacological action?
It has a similar action to barbiturates.
What is a benefit of propofol anesthesia?
It has rapid recovery and antiemetic properties.
What is a unique feature of ketamine anesthesia?
It is used in trauma cases where cardiovascular depression is necessary.
What is the term used to describe ketamine anesthesia?
Dissociative anesthesia.
What is the elimination half-life of etomidate?
2.9 hrs
What is a characteristic of propofol?
It is very lipid soluble.
What is the onset of action of propofol?
50 seconds
What type of anesthesia are drugs that are inhaled as gases or vapors?
Inhalation anesthesia
What is the typical effect of propofol injection in inducing general anesthesia in adults?
Unconsciousness within 30-40 seconds
What is the stage of anesthesia characterized by excitement, shouting, and violent behavior?
Stage II
What is the purpose of co-administering an IV skeletal muscle relaxant during general anesthesia?
To facilitate intubation and muscle relaxation
What is the typical method of inducing general anesthesia in children without IV access?
Inhalation induction with non-pungent agents
During which stage of anesthesia can surgery proceed?
Stage III
What is monitored continuously during the maintenance phase of general anesthesia?
Both vital signs and response to stimuli
What is a characteristic of Stage IV anesthesia?
Cessation of breathing and circulatory failure
What is the purpose of administering volatile anesthetics during the maintenance phase?
To control the depth of anesthesia
What is the primary benefit of general anesthesia in patients undergoing surgical procedures?
Sedation and reduction of anxiety
Why are opioids often used in combination with inhalation agents during general anesthesia?
Because inhalation agents are not good analgesics
What happens to reflexes during Stage II anesthesia?
They are enhanced
What can be used to avoid Stage II anesthesia?
I.V anesthetics
During the maintenance phase, what is the goal of monitoring the patient's vital signs and response to stimuli?
To carefully balance the amount of drug inhaled and/or infused with the depth of anesthesia
What is the primary purpose of using IV infusions of various drugs during the maintenance phase?
To supplement inhalation agents
What is the characteristic of breathing during Stage III anesthesia?
Regular
What is the final benefit of general anesthesia mentioned in the content?
Suppression of undesirable reflexes
Study Notes
Inhalation Anesthesia
- Inhalation anesthetics are used to maintain anesthesia after administration of I.V anesthetics
- Induction and recovery depend on potency and efficacy, which depend on lipid solubility
Types of Inhalation Anesthetics
- Inorganic agent: nitrous oxide (N2O)
- Non-flammable halogenated hydrocarbons: halothane (Fluothane®), isoflurane (Forane®), desflurane (Suprane®), sevoflurane (Ultane®)
- Ethers: isoflurane (Forane®), desflurane (Suprane®), sevoflurane (Ultane®)
Minimum Alveolar Concentration (MAC)
- MAC is the concentration of an anesthetic required to eliminate movement in 50% of patients when exposed to skin incision
- Anesthetic agents with higher MAC have lower potency (e.g., N2O has a MAC of 100)
- Examples of MAC values: halothane (0.75), ether (2), enflurane (1.5)
Factors Affecting Transfer of GA from Lung to Blood then Brain
- Solubility in blood (inverse relationship with speed of induction)
- Anesthetic concentration in inspired air (increased concentration increases rate of induction)
- Pulmonary ventilation (rate of induction directly depends on rate and depth of ventilation)
Intravenous Anesthetics
- Etomidate (Amidate®): short elimination half-life (2.9 hrs), has a greater margin of safety due to limited effects on CVS and respiratory system
- Propofol (Diprivan®): short recovery time, associated with less nausea and vomiting, rapid onset of action (50 sec), and recovery time (4-8 min)
- Ketamine: can be given I.V or I.M, used in trauma cases and painful procedures in children, produces dissociative anesthesia
Stages of Anesthesia (Depth)
- Stage II (delirium): from loss of consciousness to beginning of surgical anesthesia, characterized by excitement, shouting, crying, and violent behavior
- Stage III (surgical anesthesia): patient is unconscious, surgery may proceed during this stage, characterized by regular breathing and muscle relaxation
- Stage IV (medullary paralysis): seen only with overdose, characterized by cessation of breathing, circulatory failure, and death
General Anesthesia
- Provides five important benefits: sedation and reduction of anxiety, lack of awareness and amnesia, skeletal muscle relaxation, suppression of undesirable reflexes, and pulmonary blood flow
- Can be induced with IV anesthetic like propofol, followed by additional inhalation and/or IV drugs to produce the desired depth of surgical anesthesia
- In children, inhalation induction is used with non-pungent agents like halothane or sevoflurane to induce general anesthesia
This quiz covers the concepts of inhalation anesthesia, its administration, and effects on consciousness and skeletal muscle relaxation.
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