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Pharm II > Test 3: Comparison of Volatile Agents > Flashcards

Test 3: Comparison of Volatile Agents Flashcards

1
Q

What are the side effects of Enflurane?

A

-Nephrotoxic
-Inc CBF, inc ICP, inc CSF production
-Avoid in neuro cases

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2
Q

What are the CV Effects of Isoflurane?

A

-Dec MAP due to dec SVR
-Inc HR (mild)
-Dec CO (or no change)
-Coronary vasodilator (more than any other volatile!!)
-Coronary Steal Syndrome risk (reduce risk by keeping them normotensive and maintaining perfusion pressure)

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3
Q

What are the CNS effects of Isoflurane?

A

-Inc CBF and ICP at >1 MAC (less than all other agents)
-Dec CMRO2 more than any other volatile
-Preserves autoregulation
-Cerebral Protective

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4
Q

What are the Respiratory effects of Isoflurane?

A

-Decreases tidal volume (similar to other volatiles)
-Slight inc in RR
-Very decreased MV
-Decreased response to CO2
-Increased PaCO2
-Bronchodilator

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5
Q

What are the Misc effects of Isoflurane?

A

-Halogenated methyl ethyl ether
-Isomer of enflurane
-Most widely used volatile (cheap)
-Stable in storage
-Very minimal hepatic metabolism (0.2%)
-Can dec renal blood flow -> Dec GFR and Dec UOP (avoid by maintaining BP within autoregulation parameters)

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6
Q

What are the CV effects of Halothane?

A

-Decreases MAP from direct myocardial depression
-No impact on SVR
-Increased incidence of ventricular arrhythmias (junctional rhythms or bradycardia from slowed SA node conduction)
-Increases the arrhythmogenic properties of Epi (ED50 of Epi 1.5-2.1mcg/kg)

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7
Q

What are the Respiratory effects of Halothane?

A

-Bronchodilation
-Decreased Tidal Volume, Increased RR
-Decreases response to CO2 (less than other agents)
-SEVERELY depresses the hypoxic drive (problem for COPD and OSA patients)

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8
Q

What are the CNS effects of Halothane?

A

-Significant increases in CBF, increases ICP > than other agents
-Decreases CMRO2
-Autoregulation is blunted and completely abolished at high concentrations (!!)

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9
Q

What is the metabolism of Halothane?

A

-Metabolized more than any other agent
-Oxidative/reductive metabolism involving CYP450 (!) (only volatile agent to undergo reductive metabolism)
-Metabolized 20% with the first exposure, and increases with repeated exposures.
-More hepatotoxic than other agents (!)

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10
Q

What are the metabolites of Halothane?

A

Bind to hepatocytes, causing damage.
-Trifluoroacetic acid (TFA)
-Free bromide
-Free chloride

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11
Q

What are the misc effects of Halothane?

A

-Halogenated Alkane
-Clear & colorless with pleasant odor
-Non-irritating to airways
-Inhalation induction
-Thymol added as a preservative to enhance stability
-Most potent historically (now Iso is the most potent)

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12
Q

What are the Misc effects of Desflurane?

A

-Halogenated methyl ethyl ether
-Less potent than other volatile agents (MAC 6%)!!
-Pungent, airway irritant -> coughing, laryngospasm if awake.
-Minimal metabolism (!)
-Most expensive agent
-Good choices for super obese or really bad liver failure.

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13
Q

What is the Vapor Pressure of Desflurane?

A

664 mmHg

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14
Q

Why does Desflurane need a special vaporizer?

A

-Cannot be exposed to room air (directly inserted and tipped up to fill vaporizer) due to increased Vapor Pressure -Necessitates special heated and pressurized vaporizer
-Tech 6

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15
Q

Why does Desflurane have a rapid onset?

A

Less potent = faster onset. Doesn’t stay in the bloodstream. Goes into other compartments easily.
-Low solubility

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16
Q

Why does Desflurane have a prompt recovery?

A

Don’t have to wait for metabolism: concentration gradient helps with recovery.
-It’s not getting saturated in fatty tissues and hanging out there.
-Not required to wait around for liver metabolism.
-If good pulmonary mechanics are happening, should be able to get this off quickly.

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17
Q

What are the Cardiac effects of Desflurane?

A

-Rapid inc in concentrations lead to transient inc in HR
-Can confound pain indicators (causes tachycardia)
-Does not increase coronary artery blood flow
-Effect on other organ systems similar to Isoflurane

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18
Q

What is the metabolism and metabolites of Sevoflurane?

A

-2-5% metabolized
-Metabolites: inorganic fluoride,
hexafluoroisopropanol

19
Q

What is important to know about Sevo and CO2 Absorbents?

A

-Breaks down to Compound A in the presence of strong bases found in CO2 absorbents
-Nephrotoxic
-Moved away from Soda Lime so not as big of a problem anymore

20
Q

What are the misc. effects of Sevo?

A

-Halogenated Methyl Isopropyl Ether
-Rapid induction
-Prompt recovery
-Non-pungent (!)
-Lowest degree of airway irritation among currently used volatile anesthetics (!)
-Inhalational Induction agent (!)
-Can spontaneously degrade in a glass bottle (!)

21
Q

What kind of gas is Xenon?

A

Noble gas.
-Colorless, odorless
-Low chemical reactivity

22
Q

What are the effects of Xenon?

A

-Mac 71%
-B:G Solubility = 0.14
-Induction & Emergence is 3-4xs faster than Des or Sevo
-Non-explosive
-Minimal cardiac depression
-No metabolic effects
-Not harmful to the environment
-Potential risk of recall (!)
VERY Expensive. Extremely high cost has hindered its acceptance into clinical practice (BLUE BOX)

23
Q

How is Nitrous Oxide stored?

A

Stored as a liquid and a gas in pressurized tanks.
-Non flammable, but Does support combustion (!)
-Stable at room temp

24
Q

Anesthetic effects of N2O and other volatile agents are _____. Usually used in concentrations of __ - __ % to reduce the requirements of more potent agents. (Blue Box)

A

Anesthetic effects of N2O and other volatile agents are additive. Usually used in concentrations of 50%-70% to reduce the requirements of more potent agents.

25
Q

How is N2O eliminated?

A

Almost entirely eliminated via the lungs.
-Approx. 1% undergoes metabolism.

26
Q

The analgesic effects of 50% N2O are approx. equal to ___ mg of Morphine.

A

The analgesic effects of 50% N2O are approx. equal to 10 mg of Morphine.

27
Q

What are the effects of Nitrous Oxide on the CNS?

A

-Increases CBF: potent vasodilator. Can be attenuated with hyperventilation.
-Minimal inc in CMRO2 (different from most volatiles)
-Minimal EEG changes
-No effect on autoregulation
-BIG inc in PONV (theoretically due to activation of the CTZ and vomiting center of medulla and connections to expansion of middle ear causing balance issues)

28
Q

What are the cardiac effects of Nitrous Oxide?

A

-No significant change in HR, CO, or BP
-No significant change in ECG
-Mild, transient stimulation of SNS
-Inc Pulm. Vascular Resistance.

29
Q

What is important to know regarding Nitrous Oxide and Pulmonary Vascular Resistance?

A

-N2O increases PVR.
-Exaggerated in patients with pre-existing pulmonary hypertension
-Neonates are especially vulnerable (Bronchopulmonary Dysplasia (BPD) or Respiratory Syncytial Virus (RSV) avoid N2O)
-Inc PVR in patients with congenital heart defects/diseases may result in inc R-to-L shunt (inc in deoxygenated blood circulating to the body, bypassing the lungs).

30
Q

What are the respiratory effects of Nitrous Oxide?

A

-Mild dec in tidal volume and inc in RR
-Minute ventilation really no change, maybe slightly less than normal
-Hypoxic respiratory drive markedly decreased
-Ventilatory response to inc CO2 affected

31
Q

Does N2O have renal effects?

A

No significant effects on kidney function

32
Q

What are the hepatic effects of Nitrous Oxide?

A

Mild dec in hepatic blood flow

33
Q

What are the neuromuscular effects of Nitrous Oxide?

A

-Does NOT provide muscle relaxation (different from volatiles)
-Can actually increase muscle tone in high concentrations
-Does NOT trigger MH

34
Q

What are the hematologic effects of Nitrous Oxide?

A

-Inhibits enzymes that are Vitamin B12 dependent (Ex: Methionine synthetase)
-Causes bone marrow suppression (megaloblastic anemia)
-Causes peripheral neuropathies & pernicious anemia (disrupts DNA synthesis)

35
Q

What are the effects of N2O on OB patients?

A

-Does NOT alter uterine smooth muscle contractility
-Will not start or stop labor
-Avoid repeated or lengthy use in 3rd trimester (Nagelhout).
-Inhibits methionine synthase (necessary for DNA synthesis), and teratogenic effects are seen in animal studies with high concentrations for prolonged periods. Some providers avoid N2O in pregnant patients.

36
Q

What are the effects of N2O on a fetus?

A

-Increased incidence of spontaneous abortion with chronic exposure
-May be hazardous during 1st trimester due to issues with maturation
-Risk of brain development issues

37
Q

What are the maximum amounts of Volatiles/N2O allowed in the air by NIOSH?

A

-2 ppm of Volatile
-25 ppm of Nitrous Oxide

OR air is filtered every 4 minutes

38
Q

N2O is ___ times more soluble in the body than Nitrogen.

A

N2O is 34 times more soluble in the body than Nitrogen.

39
Q

What happens if N2O enters a compliant space in the body?

A

Increase in volume

40
Q

What happens if N2O enters a non-compliant space in the body?

A

Increase in pressure

41
Q

What are examples of compliant spaces?

A

-GI tract
-Pneumoperitoneum
-Pneumothorax (Inhaling 75% N2O doubles the volume in 10 min)
-Air emboli
-ETT cuffs

42
Q

What are examples of non-compliant spaces?

A

-Middle Ear
-Paranasal sinuses
-Cerebral Ventricles
-Eyeball

43
Q

When are we concerned about air embolism?

A

In surgeries where the incision site is above the heart.
-Taking down highly vascularized tissues
-Inc CVP so air can’t be sucked into open venous sinuses
-Aspirate with CVC, patient’s right side up

Pharm II (24 decks)

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