(Respiratory) General Anesthetics

Front 1

What's the difference between local and general anesthesia?

Back 1

With general anesthesia you are unconscious, while with local you are not

Front 2

What are the four major objectives of anesthesia?

Back 2

Hypnosis (Loss of consciousness)
Analgesia (loss of pain)
Hyporeflexia (Decreased spinal reflexes)
Neuromuscular blockade (adequate muscle relaxation)

Front 3

What is meant by the concept of balanced anesthesia?

Back 3

Since no single anesthetic agent can optimally meet all objectives of anesthesia, you have to combine different anesthetics for different procedures.

Front 4

Which of the four stages of anesthesia produces these results?

Analgesia
Amnesia
Euphoria

Back 4

Stage 1 (Analgesia)

Front 5

Which of the four stages of anesthesia produces these results?

Excitement
Delirium
Combinative behavior

Back 5

Stage 2 (Excitement)

Front 6

Which of the four stages of anesthesia produces these results?

Unconsciousness
Regular respiration
Decreased eye movement

Back 6

Stage 3 (Surgical anesthesia)

Front 7

Which of the four stages of anesthesia produces these results?

Respiratory arrest
Cardiac depression / arrest
No eye movement

Back 7

Stage 4 (Medullary depression)

Front 8

Which types of anesthetics seem to trigger stage II (Excitement) of anesthesia?

Back 8

This is sort of a trick question - the only one to do this is diethyl ether

Front 9

What happens when anesthetics works on the cells in the substantia gelatinosa in the dorsal horn of the spinal cord?

Back 9

Blockage of pain (nociceptive) stimuli.

This occurs starting in stage 1 of anesthesia

Front 10

In stage III of anesthesia (surgical anesthesia) where exactly are the ascending pathways blocked / depressed

Back 10

Reticular activating system

In addition spinal reflex activity suppression contributes to muscle relaxation

Front 11

Which reflexes are blocked in stage 1 of anesthesia?

Back 11

Trick question! None are

Front 12

In which of the four planes in stage III (surgical anesthesia) do you see the following?

Normal respiration
Normal pupils
Diminishing eye movements - possibly fixed stare
Loss of swallowing
Loss of conjunctival reflexes
Loss of pharyngeal reflexes

Back 12

Plane I

Front 13

In which of the four planes in stage III (surgical anesthesia) do you see the following?

Slight depression of respiratory movements
Loss of laryngeal reflexes
Loss of corneal reflexes

Back 13

Plane II

Front 14

In which of the four planes in stage III (surgical anesthesia) do you see the following?

Marked decreased in inspiration (patient will need to be on mechanical respirator)
Suppression of spinal reflexes leading to muscle relaxation

Back 14

Plane III

Front 15

In which of the four planes in stage III (surgical anesthesia) do you see the following?

Decreased depth of expiration
Pupils dilated and unresponsive to light
Loss of carinal reflex

Back 15

Plane IV

Note: This is too much anesthesia. You may have to briefly suspend anesthesia

Front 16

Which has a higher blood-gas partition coefficient, nitrous oxide or halothane?

Back 16

Halothane

Front 17

Which has a higher blood-brain partition coefficient - nitrous oxide or halothane?

What determines this number?

Back 17

Halothane is more soluble (2.9 versus 1.1 for nitrous oxide)

Lipid solubility mainly drives this number

Front 18

Which is more potent, a drug like nitrous oxide with a MAC >100 or halothane with a MAC of 0.75?

Back 18

MAC is inversely proportional to potency, so halothane with the lower MAC is more potent

Front 19

When you have a drug that is VENTILATION-LIMITED, what will hyperventilation due to the time it takes for induction?

What about for a PERFUSION-LIMITED anesthetic?

Back 19

It will be shortened for ventilation limited drugs, and lengthened for perfusion limited anesthetics

Front 20

How does the length of induction change with decreased cardiac output?

Back 20

Should be shortened due to more time for partial pressure to build up

Front 21

How does the length of induction of an anesthetic change with COPD and right to left shunts?

Back 21

Length of induction is lengthened

Front 22

(T/F) Agents that are highly soluble in the blood have a prolonged induction and recovery

Back 22

True

Front 23

Why is induction slower with a more blood soluble anesthetic?

Back 23

Since it takes much more of a soluble drug to saturate the blood, it takes much more of the drug to reach the blood brain barrier

Front 24

Name 4 ventilation limited anesthetics:

Back 24

Diethy ether
Enflurane
Isoflurane
halothane

Front 25

Name 3 perfusion-limited anesthetics:

Back 25

Nitrous oxide
Desflurane
Sevoflurane

Front 26

Is this describing ventilation-limited anesthetics or perfusion-limited anesthetics?

-Slow, rate equilibration of alveolar with inspired partial pressure
-Slow induction and slow recovery
-Induction can be sped up by increase rate of rise of alveolar partial pressures (hyperventilating)

Back 26

Ventilation-limited anesthetics

Front 27

Is this describing ventilation-limited anesthetics or perfusion-limited anesthetics?

-Induction and recovery occur quickly
-Agents are less soluble in blood
-Induce anesthesia faster

Front 28

(T/F) 75% of cardiac output goes to organs representing 10% of body mass. This vessel rich group has high capacity and high flow.

Back 28

False! Everything with the sentence is okay, except the high capacity part - VRGs have low capacity

Front 29

What is the tissue/blood coefficient of lean tissues?

Back 29

About 1.0

Front 30

What is the most important organ(s) with respect to anesthetic agents?

A. Organs that filter the blood (kidney / liver)
B. Heart
C. Lungs
D. Brain

Back 30

D. Brain

Front 31

The potency of general anesthetics is related directly to their _______ ________

Back 31

Lipid solubility

The more oil soluble, the more potent the drug is

Front 32

This is the percent alveolar concentration at one atmosphere at which 50% of patients will not respond to skin incision:

Back 32

Minimum alveolar concentration (MAC)

Front 33

Which has a higher MAC: Nitrous oxide or halothane?

Back 33

Nitrous oxide has a much higher MAC

Front 34

What is a good antagonist available to correct overdoses of general anesthetics?

Back 34

Trick question! There are none. This is why you have to be careful with dosing

Front 35

Name four effects of general anesthetics on the nervous system:

Back 35

GA's:
1. Depress excitable tissue
2. Depress frequency of EEG
3. Decreased the metabolic rate of the brain
4 Decrease cerebral vascular resistance (increasing cerebral flow)

Front 36

How do you minimize the potential of cerebral edema when using general anesthetics?

Back 36

Keep the patient well ventilated and the PCO2 low

Front 37

Do general anesthetics increase or decrease urinary output?

Back 37

Decrease, due to:

Decreased BP
Vasoconstriction
ADH
Halogen radical metabolites

Front 38

Which GA has been implicated in causing liver problems?

Back 38

Halothane

Front 39

What is the underlying cause for liver damage with general anesthetics?

Back 39

Free radical metabolites leads to autoimmune induced massive hepatic necrosis

Front 40

Risk factors for GA induced liver damage:

Back 40

Women, older age, obese, and repeated exposure

Front 41

Name two general anesthetics with 'Excellent' analgesia properties:

Back 41

Diethyl Ether, Nitrous Oxide

Front 42

Name 3 general anesthetics with 'Excellent' muscle relaxation properties:

Back 42

Diethyl Ether, Isoflurane, Enflurane

Front 43

Which GA did we talk about being flammable?

Back 43

Diethyl ether

Front 44

This is the most commonly used anesthetic for children in the US because of low incidence of adverse effects

Back 44

Halothane (Fluthane)

Front 45

Which GA did we discuss in the context of causing malignant hyperthermia?

Back 45

Halothane

Also, isoflurane, sevoflurane or succinylcholine

Front 46

Three warning signs of malignant hyperthermia:

Back 46

Myopathy or neuropathy
Muscle spasms / pain
Elevated serum creatinine phosphokinase

Front 47

What demographic is most likely to get malignant hyperthermia?

Back 47

Predominantly muscular males

Peaks at 20 years old

Front 48

In this condition the body temperature rises 1 degree for every 5-10 minutes:

Back 48

Malignant hyperthermia

Front 49

What is the underlying defect in malignant hyperthermia?

Back 49

Appears to be related to calcium metabolism.

Increased myoplasmic calcium causes a decrease in respiration by the mitochondria

This leads to an increase in glycolysis and subsequent increase in lactate

Front 50

What is the treatment for malignant hyperthermia?

This is a k-n-o-w

Back 50

First, stop the offending agent and cool the body quickly

Also dantrolene helps

Front 51

Which drug has the following properties:

Non-flammable
Better skeletal muscle relaxation than halothane
Causes minimal ventricular arrhythmia
Medium rate of induction and recovery
Used as obstetric analgesic in sub-anesthetic concentrations

Back 51

Enflurane

Front 52

What are some downsides to using enflurane?

Back 52

Powerful respiratory depressant
Cardio depression
Poor effect on pain control
EEG signs of convulsion
Liver and kidney toxicity (similar to halothane)

For these reasons its use is declining

Front 53

Name the drug:

Better muscle relaxant than enflurane w/ less respiratory and cardiac depression.
May cause coronary steal and worsen angina in patients with ischemic heart disease
Expen$ive
Smells pretty bad

Back 53

Isoflurane

Think of it like enflurane's better, more sophisticated brother

Front 54

This drug is good for outpatient surgery because of its rapid induction and recovery time (5-7 minutes). Also, there is no evidence that it causes nephro or hepato toxicity

Back 54

Desflurane

Front 55

The side effects of this drug are that it causes respiratory irritation, coughing and even laryngospasm (requiring an IV inducing agent). Also it causes increased BP and HR

Back 55

Desflurane

Front 56

This drug is often used to supplement other drugs as it allows reduced dose of halogenated GA's - thus minimizing their undesirable features:

Back 56

Nitrous Oxide

Front 57

Due to low solubility in the blood, this drug displaces nitrogen and expands into air pockets

Leads to increase in pressure in bowel / middle ear. May cause pneumothorax or pneumocephalus

Back 57

Nitrous Oxide

Front 58

What is diffusion hypoxia and which drug is associated with it?

Back 58

Nitrous Oxide - Due to low blood solubility, outflow of N2O from blood into alveoli can dilute available oxygen

Front 59

This drug is closest to the ideal inhalation anesthetic. It's pleasant odor makes it useful in children. It's popular in outpatient use

Back 59

Sevoflurane

Front 60

This anesthetic is chemically unstable and can form toxic products if soda lime is used to absorb CO2 in anesthesia circuits

Back 60

Sevoflurane

Front 61

This dissociative anesthetic produces good analgesia and amnesia,
It doesn't mess with airway reflexes or respiratory depression
It abolishes bronchospasm.

Hint: It causes crazy dreams

Back 61

Ketamine

Front 62

What are some downsides to using ketamine?

Back 62

Can cause:

Emergence delirium
Not used in abdominal surgery
Contraindicated in neurosurgical procedures due to increased cerebral blood flow

Front 63

This class of drugs causes the patient to become indifferent to their surroundings, have reduced motor activity, but the patient remains responsive to voice instructions.

The prototype for this class is Innovar (a combo of fentanyl and droperidol)

Back 63

Neuroleptanalgesiacs

Front 64

Down sides to using Innovar

Back 64

Torsades to pontes (Droperidol)
Cardiac slowing (Fentanyl)
respiratory depression (Fentanyl)
Increased CSF if pCO2 increases

Front 65

Ultra-short acting _____ are used as induction agents. These produce sleep. These are not analgesic and surgery cannot be performed under theses alone

Back 65

Ultra short acting barbiturates

They do not produce analgesia or muscle relaxation.

Front 66

(T/F) When using an ultra-short acting barbiturate you must be prepared to intubate and ventilate the patient.

Back 66

True

Front 67

If you give a dose of an ultra-short acting barbiturate to a patient, he or she will be knocked out for about 5-7 minutes and then wake up. It's not because the drug is being actively metabolized. Instead, why is it?

Back 67

Due to redistribution of the drug from the brain to other tissues.

Front 68

This drug is a non-barbiturate sedative induction agent. It may cause arenocortical suppression after a single injection and is contraindicated in children < 10 years old

Back 68

Etomidate

Front 69

This method of anesthetic delivery allows you to bypass the pulmonary phase observed with inhaled GA's, but you lose moment-to-moment control of anesthesia as you must wait for circulatory and metabolic systems to lower blood levels.

Back 69

IV anesthetics

Front 70

(T/F) Barbiturates induce cerebral profusion so they should be avoided in patients with cerebral edema.

Back 70

False. Quite the opposite actually

Front 71

Why are barbiturates contraindicated in patients with acute intermittent porphyria?

Back 71

Induces hepatic ALA synthase

Front 72

This pre-anesthetic induction agent is contraindicated in children in the ICU. It is used for rapidly inducing anesthesia, also for sedating during regional anesthesia, and in patients requiring controlled ventilation.

It's good for when you don't want a patient to fight a respirator…

Back 72

Propofol