Depth of Anesthesia Flashcards

1
Q

Signs used to monitor anesthetic depth

A
  1. Physical signs (subjective)

2. Physiologic parameters of the autonomic system

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2
Q

How do you monitor neurologic depression?

A

EEG- Bi-spectral analysis

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3
Q

Bispectral analysis

A

Processed EEG that monitors cortical activity

The lower the number, the more depressed (0-100)

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4
Q

Is BIS always accurate and useful?

A

No, depends on the person, but not a practical modality in vet med

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5
Q

Physical signs of anesthetic depths

A
  1. Prescence/absence of purposeful movement in response to stimuli
  2. Muscle relaxation
  3. Lack of reflexes
  4. Autonomic signs
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6
Q

Which muscles are checked for tones?

A

Eyeball rotation, jaw tone, anal tone, abdominal muscle tone

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7
Q

Which reflexes are checked?

A

Palpebral, corneal, anal, pupillary light (not terribly useful

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8
Q

Four stages of gas anesthetic depth

A

I- Analgesia
II- Delirium
III- Surgical Anesthesia
IV- Medullary paralysis

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9
Q

Are there clear demarcations between stages?

A

No

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10
Q

What order do the reflexes dissapear in?

A

Palpebral–Pharyngeal–corneal–light

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11
Q

Can these signs/stages be disrupted by the use of other drugs?

A

Yes, they are only based on gas anesthesia so using any injectable with disrupt the signs

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12
Q

T/F:If there is no response to a particular stimulation, there will be no response to any stimulation.

A

False

Eg, lack of movement to a toe pinch does not mean that there will be lack of movement to a surgical stimulus

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13
Q

What reflex should always be present in an anesthetized patient?

A

Corneal

Gag/swallow and palpebral reflexes present indicate they are too light

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14
Q

What is assessed for a baseline idea of anesthesia depth?

A

Jaw tone- should be easily moved by two fingers and tested throughout anesthesia

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15
Q

What position of the eye suggests that an animal is too deep?

A

Central

Eyes should be rolled ventrally with no palpebral reflex

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16
Q

What is indicated with the size of the palpebral fissure

A

Small- light anesthesia, may/may not have palpebral reflex

Large- deeper plane

Always assess with jaw tone

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17
Q

What is an ocular sign of light anesthesia in a horse?

A

Tearing

18
Q

Which way do eyes tend to roll in large animals?

A

Forward

19
Q

Which animals are eye signs not helpful in?

A

Swine

20
Q

Is pupil size a good indication of anesthetic depth?

A

No, typically appears as pin point to mid size depending on drugs used

21
Q

What pupil sign is bad?

A

Fixed and dilated- medullary paralysis

22
Q

Should both eyes be assessed?

A

Yes

23
Q

Equine eye sign

A

Brisk nystagmus- reliable sign of very light anesthesia, movement risk

24
Q

Signs of Light anesthesia

A
Toe pinch +/-
Palpebral + esp horses
Corneal +
Lacrimation +/-
Eye position Central
Jaw tone +
Abdominal breathing +/-
25
Q

Signs of Moderate anesthesia

A

Palpebral
Corneal - (may be +/- in horses)
Eye position Deviated

26
Q

Signs of Deep anesthesia

A

Corneal - when too deep
Eye position central
Abdominal breathing +/-

27
Q

Gradual decrease in HR/RR is an indication of?

A

Adequate depth

28
Q

Autonomic response is responsible for…

A

Increase in HR/RR at induction

Avoid excessive excitation at induction

29
Q

Common causes of Increased RR

A
  1. Too light (pain/stimulation)
  2. Hypercapnia
  3. Hypoxemia
  4. Hyperthermia
30
Q

Common causes of Increased BP

A
  1. Pain/stimulation

2. Renal dz/ catecholamine releasing tumors

31
Q

Common causes of Increased HR

A
  1. Pain/stimulation
  2. Hypovolemia/hypotension
  3. Hypercapnia
  4. Hypoxemia
  5. Recovery phase
32
Q

Common causes of Decreased RR

A
  1. Drugs- Opioids
  2. Too deep
  3. Medullary ischemia (apnea)
33
Q

Common causes of Decreased BP

A
  1. Effect of most anesthetic agents

2. Shock/hypovolemia

34
Q

Common causes of Decreased HR

A
  1. Vagal stimulation- drugs, visceral manuvering
  2. Hypothermia
  3. End stage overdose
35
Q

What can be heard with an esophageal stethoscope?

A

Heart rate and rhythm, breath sounds

36
Q

Ideal heart rates

A
Small dogs 70-120
Large dogs 50-100
Cats 120-180
Horse 25-40
Calves/Sheep/Goats 80-120
Bovine 60-90
37
Q

What respiratory rates is appropriate?

A

Depends on tidal volume

If adequate PaCO2 then monitor as normal

38
Q

Pulse quality

A

Always feel pulse from femoral, radial, or lingual artery prior and after induction/intubation

Get an impression of SV or BP

39
Q

What are pale MM indicative of?

A

Low CO, poor perfusion, anemia, vasoconstricion, hypothermia

40
Q

What are pink/red MM indicative of?

A

May be normal or sepsis/vasodilation

41
Q

Anesthesia records

A

Allows of trends of vital signs
Permanent legal document
Fulfills requirement of good practice standards

42
Q

What is recorded on an anesthesia record?

A
Patient info, conditions, medications
Procedure name and performers
Drug information
HR, RR, BP, ETCO2, spO2, Temp
Any issues