Inhalation agents ________ CMRO2, cerebral metabolic O2 requirement, except for N2O?

Inhalation agents decrease CMRO2, cerebral metabolic O2 requirements N2O increases CMRO2

Inhalation Anesthesia Part 3 - Quiz 6 Flashcards by Donny Le

What is the relationship of the concentrations of Des, Sevo, and Isoflurane have with Mean Arterial Pressure?

As the concentration of these gases increase, MAP decreases in a dose dependent manner d/t a decrease in SVR

How well did you know this?

Not at all

Perfectly

Out of Des, Sevo, and Isoflurane, which gas has the least Dose-Response relationship in regards to MAP

Sevoflurane

How well did you know this?

Not at all

Perfectly

How does Halothane decrease MAP?

Halothane decreases MAP by decreasing Cardiac Output

How well did you know this?

Not at all

Perfectly

How does N₂O affect the MAP?

N₂O mi**ldly increases MAP if at all

Activates SNS to increase SVR

How well did you know this?

Not at all

Perfectly

What happens if you add N₂O to other gases?

Decreases the magnitude of BP drop

How well did you know this?

Not at all

Perfectly

At what concentration of Isoflurane would you start to see HR increase?

0.25 MAC

How well did you know this?

Not at all

Perfectly

At what concentration of Desflurane would you see start to see a HR increase?

< 1 MAC: mininmal HR increase

≥ 1 MAC: linear dose dependent HR increase

How well did you know this?

Not at all

Perfectly

At what concentration of Sevoflurane would you start to see a HR increase?

> 1.5 MAC

How well did you know this?

Not at all

Perfectly

How do Inhalation Anesthetics affect Cardiac Index?

Cardiac Index is minimally influenced by gases

How well did you know this?

Not at all

Perfectly

What are the Circulatory Effects with an abrupt increase of Desflurane & Isoflurane

to > 1 MAC?

Transient Circulatory Stimulation - increased plasma Epi & Norepi

Not seen w/ other gases

How well did you know this?

Not at all

Perfectly

How do gases (except for Halothane) effect Myocardial Conduction?

Does not cause PVC’s d/t prolonging effective refractory period

Halthone makes it easier for PVCs to happen

How well did you know this?

Not at all

Perfectly

How do Inhaled Anesthetics affect the QT Interval?

Prolongs QT Interval

Avoid Sevo in pts w/ Long QT Syndrome

How well did you know this?

Not at all

Perfectly

What is Coronary Steal?

Side effect of Isoflurane that can worsen myocardial ischemia - Not found valid

Reduced blood flow from ischemic part of the heart & increases blood flow to the healthy part of the heart

How well did you know this?

Not at all

Perfectly

What is Ischemic Preconditioning?

Anesthetic gas exposes heart to brief episodes of ischemia that protects it from subsequent prolonged ischemia
Present in all tissues

How well did you know this?

Not at all

Perfectly

When do the Two Periods of Ischemic Preconditioning occur?

1-2 hours after episode
24 hours later & lasts 3 days

How well did you know this?

Not at all

Perfectly

What is the crucial event in Ischemic Preconditioning that causes the protective activity?

Opening of ATP-Sensitive Potassium (K_ATP)

30-40% d/t this

How well did you know this?

Not at all

Perfectly

How does the concentration of anesthetic gas relate to Respiratory Rate & Tidal Volume?

As gas concentration increases, Respiratory Rate increases & Tidal Volume decreases

How well did you know this?

Not at all

Perfectly

How does anesthetic gas affect Minute Ventilation, Gas Exchange & PaCO₂?

Minute Ventilation: Same

↑Dead Space Ventilation

↑PaCO2

↓Gas Exchange

How well did you know this?

Not at all

Perfectly

How does Anesthetic Gas affect Respiratory Response to CO₂?

Dose Dependent decreased/blunted response to CO₂

How well did you know this?

Not at all

Perfectly

How does Anesthetic Gas affect the Chest Wall?

Diaphragm goes toward the Head

Ribs go Inward

Results in Decreased FRC & Atelectasis

How well did you know this?

Not at all

Perfectly

How does Anesthetic Gas affect Hypoxic Pulmonary Vasoconstriction (HPV)?

Limited Effect unless there is Bronchoconstriction

How well did you know this?

Not at all

Perfectly

Which volatile gases are Nonpungent?

Sevo

Halothane

N₂0

How well did you know this?

Not at all

Perfectly

Which volatiles gases are Pungent?

Desflurane & Isoflurane

Produces Irritation - Cough, Breath Holding, Laryngospasm

How well did you know this?

Not at all

Perfectly

What affect does Anesthetic Gas have on Cerebral Vascular response to PaCO₂?

No Effect

How well did you know this?

Not at all

Perfectly

Inhalation agents ________ CMRO₂, cerebral metabolic O₂ requirement, except for N₂O?

Inhalation agents **decrease** CMRO₂, cerebral metabolic O₂ requirements N₂O **increases** CMRO₂

At what MAC does Cerebral Vasodilation occur?

\> 0.6 MAC Dose-dependent increase in CBF

What happens in the 2 Phases of dose-dependent effect of inhalation agents on CBF?

* First Phase * @ 0.5 MAC: Decreased CMRO₂ offsets Vasodilation - No change in CBF * Second Phase * ≥ 1 MAC: Vasodilation takes over - Increased CBF

What are the effects of N₂O on the CNS?

Cerebral Vasodilation & ↑CMRO₂

What would you give with N₂O to counteract its effect on the CNS?

Opioids Barbituarates Propofol

Which gases would _Increase_ ICP with a MAC \> 1?

All of them @ MAC \> 1

At what MAC is CNS Autoregulation impaired?

\< 1 MAC

What is SSEP?

SamatoSensory Evoke Potentials - Evaluates integrity of Brain & Spinal Cord

How do Anesthetic Gases & N₂O affect SSEP?

Depresses Amplitude & Increase Latency of SSEP according to dose

At what MAC are Evoked Potentials abolished?

1 MAC or 0.5 MAC if Gas + N₂O

What would Increased Depth of Anesthesia look like on an EEG?

Increased Amplitude & Synchrony

As Depth of Anesthesia increases, Burst Supression occurs with _______ frequency

As Depth of Anesthesia increases, Burst Supression occurs with **greater** frequency

At what MAC will you see an Isoelectric pattern on an EEG?

1.5 - 2.0 MAC

Which gases are associated with Epileptiform Activity on the EEG?

Sevoflurane & Enflurane (Ethrane)

How do Inhalation Agents affect Neuromuscluar Activity?

Dose-Dependent skeletal muscle relaxation & enhances neuromuscular blocking drugs

Which gas from most to least triggers Malignant Hyperthermia?

Halothane \> Isoflurane \> Sevoflurane \> Desflurane

What are symptoms of Malignant Hyperthermia?

Increased EtCO2 - **Earliest/Most sensitive sign** Fever Tachycardia Cyanosis Rigidity/Trismus

What rare liver effects might result after receiving Inhaled Anesthethics?

Immune Mediated Liver Injury Liver Necrosis leading to death Caused by Trifluoroacetate Metabolite

Other than immune mediated, how else can inhaled anesthetics cause mild liver injury?

Decreased O₂ to Liver & Decreased Liver Blood Flow ↑Serum Transaminase Levels

Which gases are most hazardous to the liver due to metabolism?

**_Halothane_** \> Isoflurane \> Desflurane Halothane Hepatitis

When are Inhaled Anesthetics avoided with patients who have liver disease?

Avoid using gases in patient who previously had liver damage d/t inhaled anesthetics. Not harmful otherwise.

How does Methoxyflurane cause Nephrotoxicity?

Production of Inorganic Fluoride

How might Sevoflurane & Halothane cause Nephrotoxicity?

Sevo & Halothane breaksdown into **Compound A** --\> Prolonged exposure = Nephrotoxicity

What can happen if Sevo has been given with low fresh gas flow for over 2 hours?

Compound A --\> Proteinuria, Enzymuria & Glycosuria

Which Inhaled Anesthetic should be avoided for pts with Vitamin B Deficiency?

N₂O - stops methionine from regulating Vitamin B & Folate metabolism

What causes Homocysteine levels to increase, which increases risk for coronary events?

N₂O - stops methionine from converting Homocysteine to methionine

Why does N₂O cause air filled cavities to expand?

N₂O goes into cavity 34x faster than Nitrogen can leave the cavity, increasing the volume and pressure. This can cause a Pneumo

What happens when the Soda Lime is fully dessicated?

Carbon Monoxide production from the Gases

Which gas has the highest risk of fire when used with a fully dessicated soda lime?

Sevoflurane

What is produced when Isoflurane & Desflurane is exposed to a fully dessicated Soda Lime?

Carbon Monoxide

What is the best way to prevent Soda Lime related Fires?

Adequate Hydration of Absorbent Change Frequently & When in Doubt Turn off fresh gas b/t cases

What compounds are in the conventional CO₂ Absorbents?

94% Ca(OH)2 - Calcium Hydroxide 5% NaOH - Sodium Hydroxide 1% KOH - Potassium Hydroxide

Which gases use a Variable-Bypass Vaporizer?

Sevoflurane Isoflurane Halothane

How does a Variable-Bypass Vaporizer work?

* Two streams of fresh gas * One goes to the agent * One bypasses agent reservoir

What is the Vapor Pressure of Sevoflurane

170 mmHg

What is the Vapor Pressure of Enflurane?

172 mmHg

What is the Vapor Pressure of Isoflurane?

240 mmHg

What is the Vapor Pressure of Halothane?

244 mmHg

What is the Vapor Pressure of Desflurane?

669 mmHg

What happens if you put an Inhaled Agent in the wrong Vaporizer?

**_High-Low-High_** High VP Agent + Low VP Can = Higher amt. delivered than dialed **_Low-High-Low_** Low VP Agent + High VP Can = Lower amt. delivered than dialed

Which gas uses a special Heated Vaporizer?

Desflurane (Suprane)

How does a Tec 6 Vaporizer Work in different altitudes?

Heats Desflurane to 2 atm High Altitude = lower amt. delivered