general anesthesia

Question 1

what are the components of an ideal anesthetic agetn

Answer 1

• Unconsciousness –> hypnosis
• Amnesia –> produce sleep without recall
• Analgesia –> abolish pain (opioids)
• Skeletal muscle relaxation
• Areflexia –> eliminate noxious reflexes
• Good minute-to-minute control

Question 2

What are clinical conditions that are IMPORTANT TO KNOW prior to general anesthesia

Answer 2

- Family history of malignant hyperthermia

- cardiovascular problems

- respiratory disease (asthma, COPD, smoking)

- Allergies to medicine and food

Question 3

What are the advantages and disadvantages of inhalable anesthetic agenst

Answer 3

• ADVANTAGE:

–> easy to control the depth of anesthesia

–> readily reversible, minute-to-minute control

• DISADVANTAGE:

–> induction not as fast or smooth as with fixed agents

Question 4

List the factors that determine uptake and distribution of inhaled anesthetics

Answer 4

Rate of anesthetic onset and recovery

1) anesthetic conc in inspired air
2) pulmonary ventilation rate
3) solubility in blood and lipid
4) pulmonary blood flow
5) arteriovenous concentration gradient
6) elimination

Question 5

Describe the effects of anesthetic concentration in inspired air on uptake and distribution of INHALABLE ANESTHETICS

Answer 5

• Proportional to its PARTIAL PRESSURE or TESNION (conc of anestheitc gas increases as partial pressure increases)
• Partial pressure depends on ability to vaporize each agent (heat of VAPORIZATION)
• Gas molecules move down partial pressure gradient (Px higher –> Px lower)

Question 6

describe how the pulmonary ventilation rate effects the uptake and distribution of inhalable anesthetics

Answer 6

Question 7

describe how solubility in blood and lipid effects uptake and distribution of inahlable anesthetics

Answer 7

1) Blood: gas partition coefficient (otswald coefficient) = SOLUBILITY IN BLOOD
2) Brain: blood partition coefficient = SOLUBILITY IN LIPID

**Lower Coeff. –> less soluble –> more rapid rise in partial pressure in blood –> faster equilibration with brain and induction**

Question 8

describe how pulmonary blood flow/cardiac output effects uptake and distribution of inhalable anesthetics

Answer 8

• High blood flow –> slower Px in blood/brain –> SLOWER ONSET
• Low blood flow –> faster Px rise in blood/brain –> FASTER ONSET

Question 9

describe how elimination will effect the uptake and distribution of inhalable anesthetics

Answer 9

• Reverse of the process for uptake
• DEPENDENT MAINLY ON BLOOD: GAS PARTITION COEFFICIENT (otswald)

_**** LESS SOLUBLE –> FASTER ELIMINATION****_

Question 10

describe anesthetic potency as it is releated to MAC

Answer 10

• Minimum alveolar concentration (MAC)

–> Lower MAC = more potent

–> High lipid solubility = MORE POTENT Anesthetic (lower MAC)

• MAC values of the inhaled anesthetics are ADDITIVE

Question 11

what are the general adverse effects of inhalable anesthetics

Answer 11

• depression of cardiovascular function (decrease CO, hypotension, arrythmias)
• Depression of respiration and response to CO2
• Decreased blood flow to liver and kidneys
• Organ toxicity
• Malignant hyperthermia = occurs in genetically susceptible individuals with inhalabe anesthetics combined with paralytics

Question 12

describe the advantage and disadvantages of intravenous anesthetic agents

Answer 12

**Used for INDUCTION and maintenance of anesthesia**

• Advantages

–> quick, easy and smooth induction

–> rapid and complete recovery

• Disadvantages

–> cant reverse the effects, except via metabolism

–> slow elimination