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?

18
Q

Which way do eyes tend to roll in large animals?

19
Q

Which animals are eye signs not helpful in?

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?

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
Signs of Moderate anesthesia
Palpebral Corneal - (may be +/- in horses) Eye position Deviated
26
Signs of Deep anesthesia
Corneal - when too deep Eye position central Abdominal breathing +/-
27
Gradual decrease in HR/RR is an indication of?
Adequate depth
28
Autonomic response is responsible for...
Increase in HR/RR at induction Avoid excessive excitation at induction
29
Common causes of Increased RR
1. Too light (pain/stimulation) 2. Hypercapnia 3. Hypoxemia 4. Hyperthermia
30
Common causes of Increased BP
1. Pain/stimulation | 2. Renal dz/ catecholamine releasing tumors
31
Common causes of Increased HR
1. Pain/stimulation 2. Hypovolemia/hypotension 3. Hypercapnia 4. Hypoxemia 5. Recovery phase
32
Common causes of Decreased RR
1. Drugs- Opioids 2. Too deep 3. Medullary ischemia (apnea)
33
Common causes of Decreased BP
1. Effect of most anesthetic agents | 2. Shock/hypovolemia
34
Common causes of Decreased HR
1. Vagal stimulation- drugs, visceral manuvering 2. Hypothermia 3. End stage overdose
35
What can be heard with an esophageal stethoscope?
Heart rate and rhythm, breath sounds
36
Ideal heart rates
``` Small dogs 70-120 Large dogs 50-100 Cats 120-180 Horse 25-40 Calves/Sheep/Goats 80-120 Bovine 60-90 ```
37
What respiratory rates is appropriate?
Depends on tidal volume If adequate PaCO2 then monitor as normal
38
Pulse quality
Always feel pulse from femoral, radial, or lingual artery prior and after induction/intubation Get an impression of SV or BP
39
What are pale MM indicative of?
Low CO, poor perfusion, anemia, vasoconstricion, hypothermia
40
What are pink/red MM indicative of?
May be normal or sepsis/vasodilation
41
Anesthesia records
Allows of trends of vital signs Permanent legal document Fulfills requirement of good practice standards
42
What is recorded on an anesthesia record?
``` Patient info, conditions, medications Procedure name and performers Drug information HR, RR, BP, ETCO2, spO2, Temp Any issues ```