General Anesthesia

Question 1

General Anesthesia definition

associated with what physical effects?

Three Goals

Answer 1

clinical state of induced loss of consciousness or total insensibility in a reversible manner

associated with DECREASED RESPIRATION and DECREASED BP

Triad - asleep, pain free, still

Question 2

Ideal Anesthetic agent effects? (6)

Answer 2

unconsciousness
amnesia
analgesia
skeletal muscle relaxation
Areflexia
good minute-to-minute control

Question 3

5 Adjuvant or Pre-anesthetic drug classes

Answer 3

anxiety - benzo's
allergic rxn prevention - anti-histamine
nausea/vomiting - anti-emetics
analgesia - opioids
prevent bradycardia/secretion - atropine

Question 4

FOUR Major Consideration prior to anesthesia

Answer 4

FAMILY HX OF MALIGNANT HYPERTHERMIA

CARDIOVASCULAR PROBLEMS

RESPIRATORY DISEASE

MED/FOOD ALLERGIES

Question 5

4 Phases of General Anesthesia

Answer 5

Induction
Maintenance
Emergence
Recovery

Question 6

Brain Stages of General Anesthesia

Answer 6

Analgesia
Excitement
Surgical Anesthesia
Medullary Depression

Goal is to pass excitement stage as quickly as possible

Question 7

Two Major Sub-types of General Anesthetics

Answer 7

Inhalable - gases or vapors - primarily for MAINTENANCE

I.V. or Fixed - primarily for INDUCTION

Question 8

Three General MOA of General Anesthetics

Answer 8

Induce NEURONAL HYPERPOLARIZATION

Increase FIRING THRESHOLD

Inhibit SYNAPTIC TRANSMISSION and RESPONSE TO NEUROTRANSMITTERS

Question 9

Factors that determine uptake and distribution of inhaled anesthetic (6)

Answer 9

anesthetic concentration
pulmonary ventilation rate
solubility
pulmonary blood flow
arteriovenous concentration gradient
Elimination

Question 10

Anesthetic Concentration in Inspired Air

Answer 10

INCREASE IN CONCENTRATION = INCREASE PARTIAL PRESSURE IN LUNG = FASTER ACCUMULATION OF ANESTHETIC IN BLOOD

Question 11

Pulmonary Ventilation Rate

Answer 11

Partial pressure of anesthetics WITH HIGHER SOLUBILITY are affected

Increased ALVEOLAR VENTILATION = MORE GAS MOLECULES/TIME = FASTER anesthesia onset

Question 12

Solubility of anesthetic in blood

Answer 12

Blood gas partition co-efficient - LOWER = LESS SOLUBLE = MORE RAPID RISE in partial pressure in blood = FASTER EQUILIBRATION with brain = FASTER INDUCTION

Question 13

Solubility of anesthetic in lipid

Answer 13

Brain:blood partition coefficient

MORE LIPID SOLUBLE = MORE POTENCY

Question 14

Pulmonary Blood Flow and Cardiac Output affects on anesthesia

Answer 14

HIGH BLOOD FLOW = SLOWER ONSET - d/t increased distribution to other tissues

LOW BLOOD FLOW = FASTER ONSET

Question 15

Elimination affects on anesthesia

Answer 15

LESS SOLUBLE = FASTER ELIMINATION

Question 16

Minimum alveolar concentration MAC

Answer 16

concentration of anesthetic in inspired air at equilibrium when there is NO RESPONSE TO NOXIOUS STIMULUS

lower MAC = MORE POTENT ANESTHETIC

High lipid solubility = lower mac = MORE POTENT

Question 17

MAC values are _____

Answer 17

additive WITH INHALED ANESTHETICS

Question 18

Gaseous Anesthetic

Answer 18

Nitrous Oxide

Question 19

Volatile Anesthetics (3)

Answer 19

Isoflurane
Desflurane
Sevoflurane

Question 20

Nitrous Oxide characteristics

Major limitation?

Answer 20

almost ideal

LOW BLOOD/GAS COEFFICIENT

GOOD ANALGESIA
SAFE

INCOMPLETE ANESTHETIC - potency is low - MAC value is 110%

Question 21

2nd Gas Effect with N2O

Answer 21

REDUCES INDUCTION TIME for primary agent

DECREASES CONCENTRATION REQUIREMENT of primary agent

DECREASES TOXICITY of primary agent

Question 22

Disadvantages of N2O

Answer 22

LACK OF POTENCY

DIFFUSION HYPOXIA - with abrupt discontinuation

Question 23

Uses of N2O

Answer 23

CANNOT BE USED AS SOLE ANESTHETIC AGENT

Question 24

Halothane Characteristics (4)

Answer 24

PROTOTYPE HALOGENATED AGENT

SLOWER RECOVERY

DECREASED CO AND HYPOTENSION

HEPATOTOXIC

Question 25

Enflurane Important Notes

Answer 25

CNS STIMULATION EFFECTS - convulsive patterns, EEG changes

Question 26

Isoflurane Important Notes (4)

Answer 26

TYPICALLY USED FOR MAINTENANCE relatively potent pungency limits mask induction use LOWER TOXICITY

Question 27

Desflurane Important Notes (3)

Answer 27

FASTEST ONSET AND RECOVERY LOWEST BLOOD/GAS COEFFICIENT = excellent MINUTE-TO-MINUTE CONTROL LESS POTENT

Question 28

Sevoflurane Important Notes (4)

Answer 28

Newest RAPID ONSET AND RECOVERY VERY POTENT EXCELLENT CONTROLLABILITY - d/t low solubility/high potency LOW AIRWAY IRRITATION - suitable for mask induction

Question 29

Intravenous Anesthetics used primarily for ______

Answer 29

INDUCTION

Question 30

Thiopental Important Notes (5)

Answer 30

BARBITURATE - CNS DEPRESSANT one of the most commonly used INDUCTION AGENTS NOT USED AS SOLE ANESTHETIC NO ANALGESIA REDISTRIBUTES TO OTHER TISSUES - fat tissue - CAN ACCUMULATE

Question 31

Propofol Important Notes (3)

Answer 31

Newer drug ONE OF THE MOST FREQUENTLY USED IV ANESTHETICS CONTINUOUS IV DRIP unlike thiopental EXCELLENT QUALITY OF RECOVERY

Question 32

Ketamine Important Notes Contraindicated in?

Answer 32

DISSOCIATIVE ANESTHESIA - intense analgesia, catalepsy, and AMNESIA EMERGENCE PHENOMENON - unpleasant dreams, hallucinations, disorientation Contraindicated in patients with PSYCH HISTORY

Question 33

Midazolam Clinical uses

Answer 33

good for SEDATION, AMNESIA, ANXIOLYTIC PROPERTIES sedation for painful procedures induction agent substitute for thiopental/propofol in high risk pts