General Anesthesia Flashcards

1
Q

Define anesthesia

What are the stages of anesthesia?

A

a combination of amnesia, analgesia, and muscle relaxation to allow the performance of surgery or other procedures

Stages

  • Induction
  • Maintenance
  • Emergence
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2
Q

Stages of anesthesia: Induction

  • AKA
  • MC induction agent and effects
  • other agents and effects
A

AKA
-“putting to sleep”

MC induction agent
-Propofol: causes drop in BP and CO, antiemetic properties

Other agents
-Etomidate: doesn’t cause vasodilation, higher rate of post op nausea, inhibits the biosynthesis of cortisol, use is limited d/t increased risk of death by 2.5x

-Ketamine: used in pts with hemodynamic instability, cardiac stimulant, significant analgesia, bronchodilation, hallucinations

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3
Q

Stages of anesthesia: Maintenance

  • Use what types of drugs
  • examples of these drugs
A

Use inhaled (volatile) or IV anesthetics

Inhalation anesthetic agents

  • volatile anesthetic agents: sevoflurane and desflurane
  • Nitrous oxide: can be used in combo with volatile gases

IV anesthetic drugs
-Propofol and remifentanil

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4
Q

Stages of anesthesia: Emergence

  • AKA
  • Can result in autonomic hyper-responsiveness, what are so signs and sx of this?
A

AKA
-Waking up

Autonomic hyper-responsiveness

  • tachycardia, hypertension, bronchospasm, laryngospasm
  • short acting narcotic, beta blockers, or lidocaine can blunt this autonomic response
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5
Q

IV Anesthetic Drugs: Propofol (Diprivan)

  • Class
  • onset of action
  • duration
  • use
  • effects
  • AE
A

Class
-Non-barbituate hypnotic agent

Onset
-40 seconds

Duration

  • 1-3 hours
  • rapid metabolized in the liver and excreted in the urine, so it can be used for long durations of anesthesia

Use
-general, cardiac, neuro, pediatric surgery

Effects

  • some anti-emetic effects
  • weaker amnestic effect than Versed
  • NO ANALGESIC EFFECT
  • clear headedness during recovery

AE

  • can support rapid growth of microorganisms
  • hypotensive (administer slowly)
  • may cause hypertonia and movement
  • resp depression
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6
Q

IV Anesthetic Drugs: Ketamine (Ketalar)

  • Onset
  • Duration
  • frequently used in what patients
  • effects
A

Onset
-30 sec

Duration
-5-10 min

Frequently used in

  • pediatric pts because anesthesia and analgesia can be obtained with IM injection
  • high risk geriatric pts and in shock cases because it provides cardiac stimulation

Effects

  • affects the senses, produces a dissociative anesthesia (catatonia, amnesia, analgesia) in which the patient may appear awake and reactive, but cannot respond to sensory stimuli
  • hallucinations
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7
Q

Anesthetic Gases

  • name four
  • where are these eliminated?
  • what are the two shortest acting?
  • how do inhaled anesthetics work?
  • CI
A

Isoflurane (Forane)

Desfluorane (Suprane)

Sevofluorane (Ultane)

Nitrous Oxide

Eliminated in the lungs.
* the more soluble the gas is in the blood, the longer it takes to eliminate

Shortest acting: nitrous oxide and desflurane because they are the least soluble in the blood

Mechanism

  • overall, they work on the CNS
  • disrupt normal synaptic transmission by
  • -interfering with the release of NT from presynaptic nerve terminal
  • -alter the re-uptake of neurotransmitters
  • -change the binding of NT to the post-synaptic receptor sites

CI

  • inability to tolerate the physiologic alterations produced
  • malignant hyperthermia (MH)
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8
Q

How are Anesthetic Gases dosed?

A

MAC (minimum alveolar concentration)
-the inhaled anesthetic concentration (steady state) at which 50% of patients move in response to a standard midline adb incision

Nitrous oxide=105%
Isoflurane= 1.15%
Sevoflurane= 1.8%
Desflurane= 6.2%

*MAC changes with age (the younger you are the more you need)

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9
Q

Anesthetic Gases: Isoflurane

  • onset
  • effects
  • AE
A

Onset
-higher blood-gas solubility so takes longer for onset and longer for emergence

Effects

  • tachycardia
  • peripheral vasodilation

AE

  • airway irritation
  • coughing
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10
Q

Anesthetic Gases: Desflurane

  • special administration requirements
  • effects
  • AE
  • onset
A

Special admin requirements
-requires a heated-pressurized vaporizer for delivery

Effects

  • tachycardia
  • peripheral vasodilation

AE
-least well tolerated on the airway: coughing, bronchospasm

Onset
-fastest onset**** and off-set of volatiles

*not used for mask induction

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11
Q

Anesthetic Gases: Sevoflurane

  • Onset
  • effects
A

Onset
-fast onset and quick awakening

Effects

  • does NOT cause tachycardia
  • causes peripheral vasodilation

*well tolerated for mask induction

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12
Q

Anesthetic Gases: Nitrous oxide

  • MAC
  • disadvantages
  • advantages
A

MAC= 105%, therefore NO alone cannot provide anesthesia

Disadvantages

  • can diffuse into air containing cavities 34 times faster than nitrogen can leave that space…bloating in the bowel, middle ear, pneumothorax, cuff of ET tubes, etc.
  • increased post-op nausea
  • High MAC/ limits FIO2
  • sympathomimetic

*has analgesic properties

Advantages
-inexpensive, readily available, odorless, limited effect, no special equipment, sympathomimetic, will not cause MH

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13
Q

Neuromuscular Blocking Drugs

  • name five
  • AKA
  • what are the types?
A

Succinylcholine (Anectine)

Rocuronium (Zemuron)

Vecuronium (Norcuron)

Pancuronium (Pavulon)

Cisatracurium (Nimbex)

AKA
-Paralytics

Types

  • depolarizing: Succinylcholine (Anectine)
  • nondepolarizing: Rocuronium (Zemuron), Vecuronium (Norcuron), Pancuronium (Pavulon), Cisatracurium (Nimbex)
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14
Q

Neuromuscular Blocking Drugs: Depolarizing agents

  • mechanism
  • drug name
  • DOC when what
  • onset
  • duration
  • AE
A

Mechanism

  • paralysis due to depolarization of the nerve terminal and the nerve being in a refractory state because the membrane is depolarized
  • causes brief twitches or fasciculations, followed by flaccid paralysis

Drug
-Succinylcholine (Anectine): SLOWLY dissociated from the ACh

DOC
-when rapid control of the airway is necessary

Onset
-less than 1 min

Duration
-6-10 min

AE

  • cardiac dysrhythmias
  • sinus bradycardia
  • myalgias
  • myoglobinuria
  • hyperkalemia
  • masseter spasm
  • MH trigger
  • possible increases in intraocular, gastric, and intracranial pressures
  • there are different genotypes for the metabolism of this med
  • cant give to children
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15
Q

Neuromuscular Blocking Drugs: Nondepolarizing agents

  • reversible or nonreversible
  • fasciculations or no fasciculations
  • what is the nest clinical marker of strength?
  • name long-acting, intermediate-acting, and short acting
A

-Reversible competition between drug and ACh binding site

NO fasciculations (because they dont depolarize)
-nerve stimulation exhibits a fade in train-of-four or tetany

Best clinical marker of strength
-sustained head-lift

Long acting
-pancuronium

Intermediate acting

  • vecuronium
  • rocuronium
  • cisatracurium

Short acting
-mivacurium

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16
Q

Name the onset and duration for each:

  • rocuronium
  • vecuronium
  • pancuronium
  • cisatracurium
A
  • rocuronium
  • -onset: 1-1.5 min
  • -duration: 35 min
  • vecuronium
  • -onset: 1.5-2 min
  • -duration: 40 min
  • pancuronium
  • -onset: 2-3 min
  • -duration: 60 min
  • cisatracurium
  • -onset: 2.5-3 min
  • -duration: 25 min
17
Q

Name metabolism and SE for each:

  • rocuronium
  • vecuronium
  • pancuronium
  • cisatracurium
A
  • rocuronium
  • -metabolism: hepatic
  • -SE: none
  • vecuronium
  • -metabolism: hepatic
  • -SE: none
  • pancuronium
  • -metabolism: renal
  • -SE: vagolytic
  • cisatracurium
  • -metabolism: other
  • -SE: none
18
Q

Describe monitoring of NMBDs

A

“Train of Four”

  • when 4 twitches are seen, 0-75% of the receptors are blocked
  • when 3 twitches are seen, at least 75% of the receptors are blocked
  • When 2 twitches are seen, 80% of the receptors are blocked
  • When 1 twitch is seen, 90% of the receptors are blocked
  • When no twitches are seen, 100% of the receptors are blocked
19
Q

How are NMBDs reversed?

A

Acetylcholine esterase inhibitors!!

Neostigmine, edrophonium result in accumulation of ACh at the NMJ

Sugammadex: no anticholinergic effects like those above. Reverses vecuronium and rocuronium