Inhalation Agents & MAC - Quiz 10 Flashcards by Donny Le

The lower the MAC the ______ potent the inhaled agent

The lower the MAC the more potent the inhaled agent

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What is MAC-Amnesia?

25% MAC

Concentration that blocks anterograde memory in 50% of awake patients

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What is MAC-Awake

50% MAC

Concentration needed to prevent eye opening on verbal command

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What is MAC-Intubation?

130% MAC

Concentration needed to prevent movement & coughing during intubation

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What is MAC-BAR?

150% MAC

Concentration needed to block autonomic/adrenergic response to incision

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What factors Increase MAC?

Babies < 6 months old - highest MAC needed

Chronic EtOH

Hyperthermia

Hypernatremia

Drugs that Increase Catecholamines

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What factors Decrease MAC?

Pregnancy
Hypothermia
Hypoxemia
Premature Babies & Elderly
Acute ETOH
Hyponatremia
Lithium
Alpha 2 Agonist/C-Channel Blockers
Bypass Machine

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How much does MAC decrease for every drop in degree of body temperature?

Every 1 degree Celsius drop = 2-5% Decrease in MAC

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What factors have ZERO effect on MAC?

Thyroid Problems

Duration of Anesthesia

Gender

Potassium Level

CO₂ Level???

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What is the MAC % of Halothane?

0.75 %

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What is the MAC % of Isoflurane?

1.15 %

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What is the MAC % of Enflurane?

1.68 %

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What is the MAC % of Sevoflurane?

2 %

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What is the MAC % of Desflurane?

6 %

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What is the MAC % of N₂O?

105 %

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How does a high Inspired Concentration affect Induction?

Speeds Indunction d/t Concentration Effect

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What does Increased Alveolar Ventilation effect Induction?

Increased Ventilation speeds Induction

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What factors are invovled in the Uptake of gas from Alveolar Space?

Gas Solubility

Cardiac Output

Alveolar/Venous Partial Pressure Difference

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What is the most important single factor in determining Induction Speed & Emergence Rate?

Solubility (Blood:Gas Partition Coefficient)

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What is the Blood:Gas for Desflurane?

0.42

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What is the Blood:Gas for N₂O?

0.47

What is the Blood:Gas for Sevoflurane?

0.68

What is the Blood:Gas for Enflurane?

1.8

What is the Blood:Gas for Isoflurane?

1.4

What is the Blood:Gas for Halothane?

2.3

A poorly soluble agent will have a _______ Induction & a _______ Emergence

A poorly soluble agent will have a **faster** Induction & a **faster** Emergence

How does a _High_ Cardiac Output affect speed of Induction?

High Cardiac Output = Slowed Induction

What enchances Uptake & Speed of Induction?

A Large Partial Pressure Difference

What Percentage of body weight is Vessel Rich: ? Vessel Poor: ? Fat: ? Muscle?

Vessel Rich: 10% Vessel Poor: 20% Fat: 20% Muscle: 50%

What percentage of Cardiac Output does each Tissue Group receive?

Vessel Rich: 75% Vessel Poor: 0% Fat: 6% Muscle: 19%

What is the Second Gas Effect?

Large intake of first gas (N₂O) causes increase rate of intake of second gas (agent)

What is Diffusion Hypoxia?

When a lot of N₂O is leaving the body into the lungs creating Hypoxia Prevention: Dont extubate on 70% N₂O & Give 100% Oxygen

What characteristics are shared by All Gases?

Bronchodilation Trigger MH Nonflammable Inhibit HPV Decrease Mucus Clearance Potentiates NMBs Flourinated Hydrocarbons

Which Gas is this?

Halothane

What gas is this?

Isoflurane

What Gas is this?

Desflurane

What Gas is this?

Sevoflurane

Which supplemental anesthetic is considered a good analgesic and does _not_ trigger MH?

N₂O

Which inhaled anesthetic should be avoided in closed gas spaces?

N₂O - 35x more soluble than Nitrogen

What complications can occur if N₂O is given in closed gas spaces?

Pneumothorax Bowel Obstruction Inner Ear Pneumocephalus Air Embolism Intraocular Bubbles

What are the effects of N₂O on patients w/ Pre-existing Pulmonary HTN?

↓Contractility ↑SVR & PVR ↑CBF

What inhibits Methionine Synthesis causing skeletal abnormalities?

50% N₂O Long Term Exposure = Peripheral Neuropathy & Megaloblastic Anemia

What serves as an O₂ sources and supports Combustion?

N₂O

How does Halothane affect the Cardiovascular System?

↓Contractility ↓Cardiac Output ↓BP & SVR Vagal Stimulation --\> Bradycardia --\> Give Atropine

Which gas was previously the most commonly used for children?

Halothane - sweet odor d/t thymol preservative

Why should caution be used when giving Epinephrine with Halothane?

Halothane makes the heart more sensitive to catecholamines causing dysrhthmias

Which gases are Pungent and increases heart rate when there is a rapid increase in dose?

Isoflurane & Desflurane

Which gas uses a special heated Vaporizer?

Desflurane - heated to 2 atm

Which gas causes Coronary Steal?

Isoflurane - blood shunted away from damaged vessels to normal vessels

Which gas is Nonpungent and is considered good for inhalation induction?

Sevoflurane - kids can tolerate high levels w/o hemodynamic changes Rapid Induction & Emergence, but can cause delerium in kids

Which gas needs to have Fresh Gas Flow \> 2L to avoid Compound A production?

Sevoflurane

Characteristics of Enflurane

↓Contractility ↓SVR ↓Renal Blood Flow - **Avoid in Renal Failure & Seizure** Profound Respiratory Depression