Inhaled Anesthetics

Front 1

Inorganic molecules

Back 1

Nitrous oxide, halogenated ethers

Front 2

How do inorganic molecules bind

Back 2

All are capable of binding to central nervous system and spinal cord neuronal membranes to produce reversible depression

Front 3

Is there a specific anesthetic receptor

Back 3

Has yet to be found. Multiple sites of action and protein targets probably exist

Front 4

How does loss of consciousness occur

Back 4

Once a critical concentration of drug has entered the brain and spinal cord, loss of consciousness ensues

Front 5

Halogenated ethers

Back 5

Isoflurane, Desflurane, sevoflurane

Front 6

What gas used to be used for anesthetic regimen

Back 6

Diethyl ether

Front 7

How are intravenous drugs and guess anesthetic combined to produce an anesthetic state

Back 7

One or two gas anesthetics are combined with a variety of IV drugs

Front 8

IV sedative induction agents

Back 8

Propofol, etomidate, neuromuscular blocking drugs, analgesics, local anesthetics

Front 9

Anesthetic technique

Back 9

Quick and pleasant induction and Recovery with maximum patient safety and efficient caseload management

Front 10

What are the most significant side effects of inhalational and intravenous anesthetics

Back 10

Respiratory side-effects

Front 11

Function of the respiratory system all five. Which ones are most important

Back 11

Metabolism, pulmonary defense, phonation, acid-base balance, gas exchange. Gas exchange and acid base balance are most important

Front 12

Function of the upper Airway

Back 12

Humidification and filtering of inspired air

Front 13

Function of the trachea bronchial tree

Back 13

Conduct gas flow to and from the alveoli

Front 14

Why does gas exchange occur where it does and where does it occur

Back 14

Occurs in the alveoli at the lower generation 17 to 19. Gas exchange requires thinner membrane to occur

Front 15

Alveoli structure

Back 15

Upright position, largest alveoli the pulmonary Apex. Each alveolus is in close contact with a network of pulmonary capillaries. Walls of alveolus asymmetrical, thin side for gas exchange, thick side for structural support.

Front 16

Three groups of inhalational Agents

Back 16

Ethers, alkanes, gases

Front 17

Examples of ethers

Back 17

Desflurane, isoflurane, sevoflurane, methoxyflurane, ether

Front 18

Example of alkanes

Back 18

Halothane, chloroform

Front 19

Examples of gases

Back 19

Nitrous oxide, cyclopropane, Xenon,

Front 20

Anesthetic agents used in the 1800's

Back 20

Nitrous oxide, first documented use of at this time. Diethyl ether. Chloroform.

Front 21

Anesthetics used in the 1920s to 1940s

Back 21

Ethylene, cyclopropane, divinyl ether. All are flammable

Front 22

What happened in the 1950s that changed the way we look at anesthetic gases

Back 22

Discoveries in fluorine chemistry.

Front 23

How many fluorine atoms do sevoflurane, desflurane and isoflurane have

Back 23

7, 6, 5 respectively

Front 24

What decrease the flammability of anesthetics

Back 24

The Act of combining fluoride with carbon decreased flammability.

Front 25

When was Halothane introduced and what was the problem with it?

Back 25

Introduced in 1951. Halothane is hepatotoxic and dysrhythmia genic meaning it causes arrhythmias especially in the presence of epinephrine.

Front 26

How are inhalational anesthetics different from other anesthetic agents

Back 26

Inhalational anesthetics have useful pharmacologic properties that are not common to other anesthetic agents

Front 27

How can you increase the appearance of a drug in arterial blood

Back 27

Putting it through pulmonary circulation

Front 28

How do the anesthetics get delivered to their various sites of action in the CNS

Back 28

A series of partial pressure gradients Propel the inhaled anesthetic

Front 29

Describe the passage of anesthetic gas once it enters the lungs

Back 29

Gas enters the lungs, alveoli, passes through the alveolar membrane into the blood, to the left side of the heart, and is distributed to the tissues of the body

Front 30

3 tissue groups that are perfused

Back 30

Vessel Rich, muscle, fat

Front 31

Sevoflurane. Vapor pressure, blood gas partition coefficient, stable and hydrated CO2 absorber, stable and dehydrated CO2 absorber. Toxic byproduct

Back 31

Vapor pressure 157. Blood gas partition coefficient 0.65. Not stable in hydrated or dehydrated CO2 absorber toxic by product is compound a

Front 32

Desflurane. Vapor pressure. Blood gas coefficient. Stable in hydrated or dehydrated CO2 absorber. Toxic byproduct.

Back 32

Vapor pressure 669. Blood gas coefficient 0.42. Stable in hydrated CO2 absorber not stable and dehydrated CO2 absorber. Toxic byproduct carbon monoxide.

Front 33

Isoflurane. Vapor pressure. Blood gas partition coefficient. Stable and hydrated or dehydrated CO2 absorber. Toxic byproduct

Back 33

Vapor pressure 238. Blood gas partition coefficient 1.46. Stable in hydrated CO2 absorber not stable and dehydrated CO2 absorber. Toxic byproduct carbon monoxide

Front 34

Nitrous. Vapor pressure. But guess partition coefficient. Stable and hydrated or dehydrated CO2 absorber. Toxic byproduct.

Back 34

Vapor pressure 38,000. Blood gas partition coefficient 0.46. Stable in hydrated and dehydrated CO2 absorber. No toxic byproduct

Front 35

Halothane. Vapor pressure. Blood gas partition.

Back 35

Vapor pressure 243. Blood gas partition 2.5.

Front 36

Vapor pressure.

Back 36

The pressure exerted by a vapor in equilibrium with its liquid or solid phase inside of a closed container. Vapor pressure is directly proportional to temperature. Increase temperature equals increase vapor pressure

Front 37

Boiling point

Back 37

The temperature at which a liquids vapor pressure exceeds atmospheric pressure in an open container

Front 38

Boiling point of desflurane

Back 38

Right around room temperature. As long as anesthetic is in closed container it will stay in liquid form.

Front 39

Partial pressure

Back 39

The fractional amount of pressure that a single gas exerts within a gas mixture

Front 40

Dalton's law of partial pressures.

Back 40

States that the total gas pressure in a container is equal to the sum of the partial pressures exerted by each gas. For any mixture of gases in a closed container, each gas exerts a pressure proportional to its fractional Mass

Front 41

Solubility

Back 41

Term used to describe the tendency of a gas to equilibrate with a solution has determining its concentration in solution.

Front 42

What makes gases more soluble

Back 42

Gases are more soluble in liquid solutions as temperature decreases. The colder the patient the longer the gas stays in the patient. The colder patient is the sleepier or patient

Front 43

Fi, fraction inspired

Back 43

The fractional concentration of anesthetic leaving the circuit

Front 44

Factors affecting inspiratory concentration, Fi

Back 44

Fresh gas leaving the anesthesia machine mixes with gases in the breathing circuit prior to being inspired.Fresh gas flow rate, volume of the breathing system, absorption by the machine or breathing circuit. Higher FD, fraction of dose delivered, and thus higher Fi increases rate of Rise of fa, fractional alveolar concentration

Front 45

Uptake

Back 45

Passage of agent from lungs to the blood.

Front 46

What happens with a greater uptake

Back 46

Slower the rate of Rise of the alveolar concentration and the lower the fa:fi ratio.

Front 47

Ideal ratio for Fa to Fi

Back 47

1. Fast induction is when the ratio of f a to f i approaches one quickly

Front 48

Factors affecting alveolar concentration, fa

Back 48

Alveolar gas concentration, fa, would approach inspired gas concentration, fi without uptake of anesthetic agent by the body. Anesthetic agent is taken up by pulmonary circulation during induction, therefore alveolar concentrations lag behind inspired concentrations. Fa/Fi less than 1

Front 49

How is the alveolar concentration related to how quickly the patient goes to sleep

Back 49

The faster the alveolar concentration is filled up, the faster the patient goes to sleep

Front 50

How does alveolar blood flow compared to cardiac output

Back 50

Alveolar blood flow is essentially equal to cardiac output

Front 51

Effect of cardiac output on induction

Back 51

As cardiac output increases, anesthetic uptake increases, the rise of alveolar pressure slows, and induction is prolonged

Front 52

Why are low output States dangerous for patients

Back 52

Low output States predisposed patients to over dosage with the more soluble agents

Front 53

How can volatile anesthetic levels affect cardiac output

Back 53

Higher than anticipated levels of a volatile anesthetic May lower cardiac output even further due to is myocardial depressant effect

Front 54

What does alveolar partial pressure determine

Back 54

Alveolar partial pressure determines the partial pressure of anesthetic in the blood and the partial pressure in the brain

Front 55

What is partial pressure of the anesthetic in the brain proportional to

Back 55

Partial pressure of the anesthetic in the brain is directly proportional to its brain tissue concentration, which determines clinical effect

Front 56

Three factors that affect anesthetic uptake

Back 56

Solubility in the blood. Alveolar blood flow. Partial pressure difference between alveolar gas and venous blood.

Front 57

Explain solubility of Agents relative to alveolar concentration

Back 57

Insoluble agents are taken up by the blood less readily than are soluble agents. As a result the alveolar concentration rise faster and induction is faster

Front 58

What are partitioned coefficients

Back 58

Partition coefficients are the relative solubilities of anesthetic agent in air, blood and tissues

Front 59

What happens when you have a higher blood gas partition coefficient

Back 59

The higher the coefficient the greater its uptake by the pulmonary circulation

Front 60

Alveolar gas to venous blood partial pressure differences

Back 60

The gradient depends on the tissue uptake.

Front 61

The transfer of anesthetic agent from blood to tissues is determined by

Back 61

Tissue solubility of anesthetic agent. Tissue blood flow.

Partial pressure difference between arterial Blood and Tissue.

Front 62

Four tissue groups based on their solubility and blood flow

Back 62

1. Vessel Rich group, brain, heart, liver, kidneys, digestive tract and endocrine organs.

Muscle group, skin and muscle.

Fat group.

The vessel poor group, bone, ligaments, teeth, hair and cartilage

Front 63

Metabolism and anesthetics

Back 63

Metabolism plays little role in opposing induction. Most gases are minimally metabolized. Enzymes saturated at less than anesthetizing dose

Front 64

Ways to speed uptake and induction of anesthesia with the inhaled anesthetics

Back 64

1. Over pressurizing and concentration affect.

2. Second gas Effect.

3. Ventilation effects.

4. Perfusion effects and ventilation perfusion mismatching

Front 65

Over pressurizing

Back 65

Equivalent to an IV bolus. The administration of a higher partial pressure of anesthetic than the alveolar concentration, (fa) actually desired for the patient. The greater The Inspired concentration of an inhaled anesthetic, the greater the rate of rise.

Front 66

How to counter lowering of alveolar partial pressure

Back 66

A lowering of alveolar partial pressure by uptake can be countered by increasing alveolar ventilation

Front 67

With what kind of anesthetic would you most likely see the effect of increasing ventilation

Back 67

This effect will be most obvious for soluble anesthetics by raising the faf I ratio. Increasing ventilation has minimal effect for insoluble agents

Front 68

How does hyperventilation affect the rate of Rise of f a

Back 68

Hyperventilation increases the rate of Rise of f a. Only with mechanical ventilation. Because hypervent in spontaneous breathing person, body would sense low concs and allow down resp rate.

Front 69

How does hypoventilation affect the rate of Rise of f a

Back 69

Hypoventilation decreases the rate of Rise of f a. Only with mechanical ventilation. Because in spontaneous breathing, Resp depression produced by high concentrations slows the rise of Fa/Fi.

Front 70

How does cardiac output affect f i

Back 70

As f i increases, greater cardiovascular depression reduces anesthetic uptake increasing the rate of Rise of FA/FI

Front 71

How does cardiac output affect insoluble agents

Back 71

4 insoluble agents, cardiac output has minimal effect

Front 72

Main factors that influence the ability to anesthetize a patient

Back 72

Technical or machine specific, drug-related, respiratory, circulatory, and tissue related

Front 73

Primary factors that influence absorption of the inhalation anesthetics

Back 73

Ventilation, uptake into the brain, cardiac output, the solubility of the anesthetic drug in the blood, alveolar to venous blood partial pressure difference

Front 74

What is the level of anesthesia related to

Back 74

The alveolar concentrations of anesthetic agents

Front 75

Definition of Mac

Back 75

It is the dose of the individual drug. It is the minimum alveolar concentration necessary to produce anesthesia in 50% of the population upon surgical stimulation.

Front 76

How does age affect Mac

Back 76

The required dose Peaks at approximately six months of age and then decreases with increasing age.

Front 77

Factors that increase Mac

Back 77

Hyperthermia, drug induced increases in CNS activity, hypernatremia, chronic alcohol abuse

Front 78

Factors that decrease Mac

Back 78

Hypothermia, increasing age, perioperative sedatives, drug-induced decreases and CNS system activities, alpha-2 Agonist, acute alcohol ingestion, pregnancy, postpartum, lithium, lidocaine, hypoxia, hypertension, bypass, hyponatremia

Front 79

Two factors that affect uptake early in anesthetic Administration

Back 79

Drug solubility in the rubber and plastic machine parts and total machine liter flow of the gases chosen

Front 80

How does drug solubility in the rubber and plastic machine parts effect uptake

Back 80

The rubber and plastic components of the machine, ventilator and absorbent, can retain small quantities of anesthetic gases. This could slow Administration to the patient effect as minimal she says 15 minutes after Administration

Front 81

Blood gas solubility coefficient

Back 81

Reflects the proportion of the anesthetic that will be soluble in the blood and not readily enter the tissues. The more soluble the drug, the higher the blood gas coefficient, the slower the brain and spinal cord uptake and therefore the slower the anesthesia is achieved. Soluble drugs stay in the blood in Greater proportion than less soluble agents, less of the drug is released to the tissues during the early rapid uptake phase of induction

Front 82

What does the blood gas coefficient mean

Back 82

Example blood gas coefficient of desflurane which is 0.42. Means that 0.42 of desflurane molecules stay in the blood for every one molecule that enters the brain.

Front 83

Why does nitrous rise in the lungs more quickly than desflurane in spite of only a slight higher blood gas solubility

Back 83

This is a result of concentration effect

Front 84

Rate of rise relationship to blood gas solubility

Back 84

The lower the blood gas solubility the faster the rate of rise in the lung and brain.

Front 85

Relationship between anesthetic blood gas solubility and uptake

Back 85

An anesthetic gas with a low blood gas solubility is not taken into the blood, therefore the alveolar concentration Rises quickly and patient achieves anesthesia quickly. An anesthetic gas with a high blood gas solubility is taken up and held in blood, resulting in slow rise and alveolar concentration and slow onset of anesthesia.

Front 86

What happens to anesthetic uptake throughout the surgical procedure

Back 86

Anesthetic uptake slow throughout the surgical procedure as the tissue compartments become more saturated

Front 87

What is the ventilation effect

Back 87

The faster and more deeply a patient breathes or is ventilated, the faster the patient loses Consciousness at the start of anesthesia and emerges at the end.

Front 88

Which agents would be more affected by deficits in ventilation perfusion or poor lung function

Back 88

Agents with low blood gas solubility, rapid acting agents are affected to a greater extent than slow-acting drugs.

Front 89

How can you compensate for decreases in speed for both soluble and insoluble drugs.

Back 89

You can increase the concentration for insoluble drugs or increase the ventilation with soluble drugs.

Front 90

Over pressuring or concentration affect

Back 90

During the first minutes of gas Administration, a higher concentration of the drug than necessary for maintenance or a loading dose is delivered to speed the initial uptake. over pressuring we'll have more of an effect on slow, more soluble, agents with a higher blood gas coefficient there for isoflurane example. It has less of an effect on Fast and soluble agents.

Front 91

Induction and maintenance doses for nitrous, isoflurane, desflurane, sevoflurane

Back 91

Nitrous: induction 50 to 70% same for maintenance.

Isoflurane: induction 1 to 4%, maintenance 0.5 to 2%.

Desflurane: induction 3 to 9%, maintenance 2 to 6%.

Sevoflurane: induction 4-8%, maintenance 1 to 4%

Front 92

Second gas effect

Back 92

The uptake of the slower agent in the alveoli and to an even greater proportion in the arterial blood, is increased by administering it with a high concentration of the faster anesthetic nitrous oxide. Simultaneous administration of a relatively slow agent such as isoflurane and a faster drug such as nitrous oxide, in high concentrations, can speed the onset of the slower agent. If the gas is already inherently fast on its own he will have less of an augmentation when given with nitrous.

Front 93

Where is the majority of blood leaving the lungs with anesthetic distributed

Back 93

Majority is distributed to the vital organs or high blood flow areas call to vessel Rich group or Central compartment. Heart, liver, kidneys, brain received more anesthetic sooner than muscles and fat. Overtime all body compartments are saturated

Front 94

During induction how does cardiac output effect on set

Back 94

Increases in cardiac output slow onset. Effect is greater with higher blood gas coefficient drugs. An increased cardiac output removes more anesthetic from the lungs which slows the rise in lung and brain concentration. Effect dissipates as anesthetic proceeds

Front 95

Equilibration of partial pressures is a result of what three factors

Back 95

1. Inhaled anesthetics are gases rapidly transferred bi-directionally via the lungs to and from the bloodstream and then to and from the CNS tissues as partial pressure equilibrates. 2. Plasma and tissues have a low capacity to absorb the inhaled anesthetics in comparison to the amount it can deliver to the lungs. This permits quick establishment or abolishment of anestheserizing concentrations in the bloodstream and CNS.

3. Metabolism, excretion, and redistribution of inhaled anesthetics are minimal relative to the rate at which they are delivered or removed from the lungs. This permits easy maintenance of blood in CNS concentrations

Front 96

How do inhaled anesthetics equilibrate

Back 96

Inhaled anesthetics equilibrate based on their partial pressures in each tissue not based on their concentrations

Front 97

How is the partial pressure of a gas in solution defined

Back 97

The partial pressure of a gas in solution is defined by the partial pressure in the gas phase with which it is in equilibrium. Where there is no gas phase is the partial pressure reflects a force to move out of solution

Front 98

What does the concentration of anesthetic in a tissue depend on

Back 98

The concentration of anesthetic in a tissue depends on its partial pressure and the tissue cells ability of the anesthetic.