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130 Cards in this Set

  • Front
  • Back
Components of General Anesthesia (4)
loss of consciousness
amnesia
analgesia
immobility in response to noxious stimuli
attenuation of autonomic response
Therapeutic index
(LD50/ED50) of inhaled agents is 2-4
Stages of General Anesthesia
Analgesia
Excitement
Surgical Anesthesia
Medullary Depression
What stage includes amnestic despite delirious behavior and autonomic dysfunction: irregular respiration, laryngospasm, incontinence, vomiting?
Excitement
Which stage do you need circulatory and respiratory support?
Medullary Depression
Dalton’s Law
partial pressure of a gas in a mixture of gases is directly proportional to its percent concentration
What is the relationship between partial pressure and soluability in a tissue?
inversely proportional
Potency
-relationship between a drug effect and the dose required to achieve it
-expressed as an ED50
What is MAC?
MINIMAL ALVEOLAR CONCENTRATION is the alveolar concentration that results in immobility in 50% of patients exposed to a noxious stimulus (ED50 for inhalational anesthetics)
When can MAC be obtained?
after a period of equilibration, where the partial pressure in the CNS equals the partial pressure in the alveoli
What is the relationship between MAC and uptake and distribution?
MAC is independent of uptake & distribution to other tissues
What is the benefit of BIS?
Confirms hypnosis, amnesia
Decreased awareness
What happens to MAC if you use 2 volatile agents?
MACs are additive with steep dose response curves
What does anesthetic adjuvants do to the MAC?
reduce MAC but the reduction has a ceiling effect
IF a gas has a high lipid soluability, what is the potency/MAC?
LOW MAC meaning high potency
What is MAC-BAR?
Concentration that blocks adrenergic (autonomic) response in 50% of patients

1.4-1.5 MAC
What is MAC-awake?
Concentration that abolishes response to verbal command / suppresses learning in 50% of patients

0.3-0.4 MAC
Factors that increase MAC
Infancy
Hypernatremia
Drugs that raise central catecholamines(Amphetamine,cocaine intoxication)
Chronic alcohol abuse
Factors that decrease MAC
Increasing age / elderly Decrease in body temperature
Pregnancy
Extreme physiological derangements
Acute alcohol intoxication
Hyponatremia
Adjuvants
MAC is independent of...
Duration of anesthesia
Thyroid disease
Muscle relaxants
Gender
Height
Weight
Anatomic sites of anesthetic action
Immobilization to surgical incision is produced by action on the spinal cord.

Amnestic actions are mediated within the brain.
Cellular mechanisms of anesthetic action
Inhibiton of excitatory synapses

Enhancement of inhibitory synapses

Minimal effect on action potentials
Molecular actions of inhaled anesthetics
Ligand-gated ion channels (GABAA)
Glycine receptors
Nicotinic receptors
NMDA receptors
Two-pore potassium channels
At equilibrium, the partial pressures between tissues are equal. The amount of agent is ____ .
different due to partition coefficients.
Halothane distribution
Very soluable in blood so takes long time to equilibrate into fat and vessel poor compartments
High cardiac output _____ the onset of the drug and elimination.
slows
What factors speed elimination and speed induction?
increased alveolar ventilation
devreased soluability
Context-sensitive half-times
Half-life or 50% decrement time depends upon the context or duration of drug administration.
Decrement times do not correspond to clinical endpoints.
Ideal Anesthetic
Smooth and rapid loss of consciousness
Prompt recovery of cognitive function after DC
Wide margin of safety
Devoid of adverse effects.
Contraindications with Volatile Anesthetics
Severe hypovolemia
Malignant hyperthermia
Intracranial hypertension-dilates vessels
CardioPulmonary effects of GAS
Decreased Blood Pressure, tidal volume.
Increases RR, apneic threshold.
Heart rate changes
Which gases decrease CO? SVR?
CO-Halothane/Enflurane
SVR-Iso/Des/Sevoflurane
Which gases change HR how?
down-halothane
no change-sevo
up-iso/des
Methoxyflurane toxicity
Halothane toxicity
Polyuric renal failure Trifluoroacetic Acid, hepatitis
Malignant Hyperthermia
Hypercarbia, Metabolic acidosis, Tachycardia, Rhabdomyolysis
50% die w/o Tx
Ideal Anesthetic
Smooth and rapid loss of consciousness
Prompt recovery of cognitive function after DC
Wide margin of safety
Devoid of adverse effects.
Halothane CV and CNS effects
Depresses myocardium
Sensitizes myocardium to catecholamines
Peripheral vasodilatation
Ventilatory depression
Cerebral vasodilation
Decreases Sympathetic tone and reflexes
Contraindications with Volatile Anesthetics
Severe hypovolemia
Malignant hyperthermia
Intracranial hypertension-dilates vessels
CardioPulmonary effects of GAS
Decreased Blood Pressure, tidal volume.
Increases RR, apneic threshold.
Heart rate changes
Isoflurane vs. Halothane
No sensitization to catecholamines
No decrease in CO
Little metabolism
Less MH
Ideal Anesthetic
Smooth and rapid loss of consciousness
Prompt recovery of cognitive function after DC
Wide margin of safety
Devoid of adverse effects.
Ideal Anesthetic
Smooth and rapid loss of consciousness
Prompt recovery of cognitive function after DC
Wide margin of safety
Devoid of adverse effects.
Sevoflurane and Desflurane
Rapid induction / emergence
Mild respiratory /cardiac effects
Few side effects
Expensive
Sevo just came off patent 2006
Differences are not dramatic
Which gases decrease CO? SVR?
CO-Halothane/Enflurane
SVR-Iso/Des/Sevoflurane
Contraindications with Volatile Anesthetics
Severe hypovolemia
Malignant hyperthermia
Intracranial hypertension-dilates vessels
Contraindications with Volatile Anesthetics
Severe hypovolemia
Malignant hyperthermia
Intracranial hypertension-dilates vessels
Desflurane vs. Isoflurane
Faster onset and offset of action
Greater muscle relaxation
BUT, Pungent odor
Requires special (heated) vaporizer
Boils at 1 atmosphere
Expensive
CardioPulmonary effects of GAS
Decreased Blood Pressure, tidal volume.
Increases RR, apneic threshold.
Heart rate changes
Which gases change HR how?
down-halothane
no change-sevo
up-iso/des
Methoxyflurane toxicity
Halothane toxicity
Polyuric renal failure Trifluoroacetic Acid, hepatitis
CardioPulmonary effects of GAS
Decreased Blood Pressure, tidal volume.
Increases RR, apneic threshold.
Heart rate changes
Sevoflurane vs. Desflurane
Standard vaporizer
Pleasant odor
Less postoperative nausea/vomiting

BUT, decreases CO, more metabolized
Which gases decrease CO? SVR?
CO-Halothane/Enflurane
SVR-Iso/Des/Sevoflurane
Which gases change HR how?
down-halothane
no change-sevo
up-iso/des
Nitrous Oxide
Inert
Colorless, odorless, tasteless
Minimal metabolism, Does not burn
Low blood solubility (quick recovery)
Little effect on respiration
Minimal effects on heart rate and blood pressure
Which gases decrease CO? SVR?
CO-Halothane/Enflurane
SVR-Iso/Des/Sevoflurane
Malignant Hyperthermia
Hypercarbia, Metabolic acidosis, Tachycardia, Rhabdomyolysis
50% die w/o Tx
Which gases change HR how?
down-halothane
no change-sevo
up-iso/des
Methoxyflurane toxicity
Halothane toxicity
Polyuric renal failure Trifluoroacetic Acid, hepatitis
Nitrous Oxide: The Bad
Low potency
Second gas effect-beginning of case
Diffusion hypoxia-end of case
Inhibits methionine synthetase
DNA synthesis
Inhibits vitamin B-12 metabolism
ABUSE
Halothane CV and CNS effects
Depresses myocardium
Sensitizes myocardium to catecholamines
Peripheral vasodilatation
Ventilatory depression
Cerebral vasodilation
Decreases Sympathetic tone and reflexes
N2O Concentration-Effect Relationships
20%-Analgesia
40%-Behavioral disinhibition
60%-Amnesia
80%-Unconsciousness
>100%-Anesthesia; Anoxia
Malignant Hyperthermia
Hypercarbia, Metabolic acidosis, Tachycardia, Rhabdomyolysis
50% die w/o Tx
Methoxyflurane toxicity
Halothane toxicity
Polyuric renal failure Trifluoroacetic Acid, hepatitis
Isoflurane vs. Halothane
No sensitization to catecholamines
No decrease in CO
Little metabolism
Less MH
Sevoflurane and Desflurane
Rapid induction / emergence
Mild respiratory /cardiac effects
Few side effects
Expensive
Sevo just came off patent 2006
Differences are not dramatic
Halothane CV and CNS effects
Depresses myocardium
Sensitizes myocardium to catecholamines
Peripheral vasodilatation
Ventilatory depression
Cerebral vasodilation
Decreases Sympathetic tone and reflexes
Malignant Hyperthermia
Hypercarbia, Metabolic acidosis, Tachycardia, Rhabdomyolysis
50% die w/o Tx
Desflurane vs. Isoflurane
Faster onset and offset of action
Greater muscle relaxation
BUT, Pungent odor
Requires special (heated) vaporizer
Boils at 1 atmosphere
Expensive
Sevoflurane vs. Desflurane
Standard vaporizer
Pleasant odor
Less postoperative nausea/vomiting

BUT, decreases CO, more metabolized
Halothane CV and CNS effects
Depresses myocardium
Sensitizes myocardium to catecholamines
Peripheral vasodilatation
Ventilatory depression
Cerebral vasodilation
Decreases Sympathetic tone and reflexes
Isoflurane vs. Halothane
No sensitization to catecholamines
No decrease in CO
Little metabolism
Less MH
Sevoflurane and Desflurane
Rapid induction / emergence
Mild respiratory /cardiac effects
Few side effects
Expensive
Sevo just came off patent 2006
Differences are not dramatic
Nitrous Oxide
Inert
Colorless, odorless, tasteless
Minimal metabolism, Does not burn
Low blood solubility (quick recovery)
Little effect on respiration
Minimal effects on heart rate and blood pressure
Desflurane vs. Isoflurane
Faster onset and offset of action
Greater muscle relaxation
BUT, Pungent odor
Requires special (heated) vaporizer
Boils at 1 atmosphere
Expensive
Isoflurane vs. Halothane
No sensitization to catecholamines
No decrease in CO
Little metabolism
Less MH
Ideal Anesthetic
Smooth and rapid loss of consciousness
Prompt recovery of cognitive function after DC
Wide margin of safety
Devoid of adverse effects.
Nitrous Oxide: The Bad
Low potency
Second gas effect-beginning of case
Diffusion hypoxia-end of case
Inhibits methionine synthetase
DNA synthesis
Inhibits vitamin B-12 metabolism
ABUSE
Sevoflurane vs. Desflurane
Standard vaporizer
Pleasant odor
Less postoperative nausea/vomiting

BUT, decreases CO, more metabolized
Sevoflurane and Desflurane
Rapid induction / emergence
Mild respiratory /cardiac effects
Few side effects
Expensive
Sevo just came off patent 2006
Differences are not dramatic
Contraindications with Volatile Anesthetics
Severe hypovolemia
Malignant hyperthermia
Intracranial hypertension-dilates vessels
CardioPulmonary effects of GAS
Decreased Blood Pressure, tidal volume.
Increases RR, apneic threshold.
Heart rate changes
Nitrous Oxide
Inert
Colorless, odorless, tasteless
Minimal metabolism, Does not burn
Low blood solubility (quick recovery)
Little effect on respiration
Minimal effects on heart rate and blood pressure
N2O Concentration-Effect Relationships
20%-Analgesia
40%-Behavioral disinhibition
60%-Amnesia
80%-Unconsciousness
>100%-Anesthesia; Anoxia
Desflurane vs. Isoflurane
Faster onset and offset of action
Greater muscle relaxation
BUT, Pungent odor
Requires special (heated) vaporizer
Boils at 1 atmosphere
Expensive
Sevoflurane vs. Desflurane
Standard vaporizer
Pleasant odor
Less postoperative nausea/vomiting

BUT, decreases CO, more metabolized
Which gases decrease CO? SVR?
CO-Halothane/Enflurane
SVR-Iso/Des/Sevoflurane
Nitrous Oxide
Inert
Colorless, odorless, tasteless
Minimal metabolism, Does not burn
Low blood solubility (quick recovery)
Little effect on respiration
Minimal effects on heart rate and blood pressure
Which gases change HR how?
down-halothane
no change-sevo
up-iso/des
Nitrous Oxide: The Bad
Low potency
Second gas effect-beginning of case
Diffusion hypoxia-end of case
Inhibits methionine synthetase
DNA synthesis
Inhibits vitamin B-12 metabolism
ABUSE
Nitrous Oxide: The Bad
Low potency
Second gas effect-beginning of case
Diffusion hypoxia-end of case
Inhibits methionine synthetase
DNA synthesis
Inhibits vitamin B-12 metabolism
ABUSE
Methoxyflurane toxicity
Halothane toxicity
Polyuric renal failure Trifluoroacetic Acid, hepatitis
Ideal Anesthetic
Smooth and rapid loss of consciousness
Prompt recovery of cognitive function after DC
Wide margin of safety
Devoid of adverse effects.
Malignant Hyperthermia
Hypercarbia, Metabolic acidosis, Tachycardia, Rhabdomyolysis
50% die w/o Tx
N2O Concentration-Effect Relationships
20%-Analgesia
40%-Behavioral disinhibition
60%-Amnesia
80%-Unconsciousness
>100%-Anesthesia; Anoxia
N2O Concentration-Effect Relationships
20%-Analgesia
40%-Behavioral disinhibition
60%-Amnesia
80%-Unconsciousness
>100%-Anesthesia; Anoxia
Halothane CV and CNS effects
Depresses myocardium
Sensitizes myocardium to catecholamines
Peripheral vasodilatation
Ventilatory depression
Cerebral vasodilation
Decreases Sympathetic tone and reflexes
Contraindications with Volatile Anesthetics
Severe hypovolemia
Malignant hyperthermia
Intracranial hypertension-dilates vessels
Isoflurane vs. Halothane
No sensitization to catecholamines
No decrease in CO
Little metabolism
Less MH
CardioPulmonary effects of GAS
Decreased Blood Pressure, tidal volume.
Increases RR, apneic threshold.
Heart rate changes
Sevoflurane and Desflurane
Rapid induction / emergence
Mild respiratory /cardiac effects
Few side effects
Expensive
Sevo just came off patent 2006
Differences are not dramatic
Which gases decrease CO? SVR?
CO-Halothane/Enflurane
SVR-Iso/Des/Sevoflurane
Which gases change HR how?
down-halothane
no change-sevo
up-iso/des
Desflurane vs. Isoflurane
Faster onset and offset of action
Greater muscle relaxation
BUT, Pungent odor
Requires special (heated) vaporizer
Boils at 1 atmosphere
Expensive
Methoxyflurane toxicity
Halothane toxicity
Polyuric renal failure Trifluoroacetic Acid, hepatitis
Sevoflurane vs. Desflurane
Standard vaporizer
Pleasant odor
Less postoperative nausea/vomiting

BUT, decreases CO, more metabolized
Malignant Hyperthermia
Hypercarbia, Metabolic acidosis, Tachycardia, Rhabdomyolysis
50% die w/o Tx
Nitrous Oxide
Inert
Colorless, odorless, tasteless
Minimal metabolism, Does not burn
Low blood solubility (quick recovery)
Little effect on respiration
Minimal effects on heart rate and blood pressure
Halothane CV and CNS effects
Depresses myocardium
Sensitizes myocardium to catecholamines
Peripheral vasodilatation
Ventilatory depression
Cerebral vasodilation
Decreases Sympathetic tone and reflexes
Nitrous Oxide: The Bad
Low potency
Second gas effect-beginning of case
Diffusion hypoxia-end of case
Inhibits methionine synthetase
DNA synthesis
Inhibits vitamin B-12 metabolism
ABUSE
Isoflurane vs. Halothane
No sensitization to catecholamines
No decrease in CO
Little metabolism
Less MH
N2O Concentration-Effect Relationships
20%-Analgesia
40%-Behavioral disinhibition
60%-Amnesia
80%-Unconsciousness
>100%-Anesthesia; Anoxia
Sevoflurane and Desflurane
Rapid induction / emergence
Mild respiratory /cardiac effects
Few side effects
Expensive
Sevo just came off patent 2006
Differences are not dramatic
Desflurane vs. Isoflurane
Faster onset and offset of action
Greater muscle relaxation
BUT, Pungent odor
Requires special (heated) vaporizer
Boils at 1 atmosphere
Expensive
Sevoflurane vs. Desflurane
Standard vaporizer
Pleasant odor
Less postoperative nausea/vomiting

BUT, decreases CO, more metabolized
Nitrous Oxide
Inert
Colorless, odorless, tasteless
Minimal metabolism, Does not burn
Low blood solubility (quick recovery)
Little effect on respiration
Minimal effects on heart rate and blood pressure
Nitrous Oxide: The Bad
Low potency
Second gas effect-beginning of case
Diffusion hypoxia-end of case
Inhibits methionine synthetase
DNA synthesis
Inhibits vitamin B-12 metabolism
ABUSE
N2O Concentration-Effect Relationships
20%-Analgesia
40%-Behavioral disinhibition
60%-Amnesia
80%-Unconsciousness
>100%-Anesthesia; Anoxia
Why do you not use nitrous with bowel surgery?
N2O exchanges with nitrogen bc N2O - 34x more soluble in blood causing the bowels to swell.
N2O Diffusion Hypoxia
blood nitrogen levels are up at the end of a case which potentiates hypoxemia.
Xenon
Inert (Noble) gas
Insoluable
Cardiovascular stability
Adequate Potentcy

BUT..expensive
Characteristics of IV Anesthetics
Lipophilic – rapid onset, offset of action
↓ Respiration: barbiturates, opioids, propofol
Myocardial depression barbiturates, propofol
Vasodilation: barbiturates, propofol
Analgesia: opioids, ketamine
Amnesia: benzodiazepines, ketamine
Barbiturates
Thiopental, others

Use: Induction

Site of Action: GABA-A receptor(subanesthetic dose) Voltage-dep Na+Channels

Contraindicated Acute Intermittent Porphyria
Imidazoles - Etomidate
Use:Induction
Sites of Action:
GABA Agonist Redistribution CNS depressant
Propofol
Flexible Drug: Induction Maintenance Sedation

Sites of Action:GABAA receptor NMDA-glutamate

Notable:vs. Thiopental Greater ↓ vascular resistance Faster recovery
Less confusion, nausea
Benzodiazepines
Example: Midazolam
Uses: Induction
Anti-anxiety
Pre-anesthetic Amnesia

Site of Action: GABA-A receptor

Antagonist: Flumazenil
Opiods
Examples: Fentanyl,Remifentanil

Uses:Analgesia Cardiac surgery Balanced anesthesia

Site of Action: Mu-opioid receptor

Antagonist: Naloxone: T1/2 = 30 minutes

Notable:Postop Nausea/Vomiting,Muscular Rigidity, Bradycardia
Uninary retention,Constipation Remifentanil hydrolyzed in plasma
Ketamine
Uses:Induction Hypovolemia Diagnostic procedures

Site of Action: NMDA-glutamate receptor

Dissociative anesthetic: Catonia,Amenesia,Analgesia, Not true surgical anesthesia, Central sympathetic stimulation
26 yr old female
No known allergies
No PMHx
Hx of nausea and vomiting with all previous anesthestics
propofol
23 yr old male
No PMHx
Just eat 7 Krystal Burgers, Fries, and a 32 ounce soda
Alert
Hypotensive
Respiratory Distress
etomidate or ketamine