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Anesthesia > Anesthesia Depth > Flashcards

Anesthesia Depth Flashcards

1
Q

An elevated ETCO2 value can indicate hypoventilation which normally indicates which…

a. Increased depth of anesthesia
b. Decreased depth = insufficient anesthesia

A

A

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2
Q

An organ considered “critical” by the anesthetist because it is part of the cardiovascular system and which receives almost a quarter of the heart output, and has the highest blood flow and oxygen consumption is the…

a. Kidney
b. Brain
c. Pancreas
d. Myocardium
e. Ilium

A

A

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3
Q

Which of the following signs would be an example of a noninvasive subjective monitoring technique?

a. Checking the patient’s pulse rate
b. Taking an Sp02
c. Watching the patient’s breathing pattern
d. Checking a patient’s jaw tone
e. Observing an End tidal capnography curve form from exhaled breath

A

D

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4
Q

All of these groups of patients are prone to moderate to severe hypothermia EXCEPT:

a. Kittens
b. Patients with low BCS
c. Brachycephalic patients
d. Cats
e. Alopecic patients

A

C

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5
Q

The ACVA recommends that all patients be monitored under sedation and anesthesia for ALL of the following EXCEPT

a. Circulation
b. Urine output
c. Oxygenation and ventilation
d. Thermoregulation
e. Anesthesia depth

A

B

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6
Q

Oxygen delivery is what we attempt to monitor and assure for our patients while they are under anesthesia. It is made up of (a product of) two things, namely

a. Systemic vascular resistance and blood pressure
b. Oxygen volume and hemoglobin concentration
c. Cardiac output and oxygen content
d. Oxygen content and carbon dioxide removal
e. Cardiac output and stroke volume

A

C

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7
Q

You have determined after viewing the patient’s jaw tone, eye position, and pupil size, and evaluating your monitors (blood pressure, pulse ox, ecg), that your patient is unfortunately light…at that time, he begins panting and even moves on the surgical table. The surgeon screams at you to “do something” to keep the patient asleep. You turn up your oxygen flow and vaporizer, but what else should you do?

a. Administer an intravenous opioid
b. Bag the patient until he’s down again
c. Ventilate the patient into submission
d. Lower your oxygen flow

A

A

  • would want to increase oxygen flow and vaporizer
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8
Q

Low respiratory rates are almost always indicative of deep planes of anesthesia but tachypneas may be indicative of all of the following EXCEPT:

a. Hyperthermia
b. Anaphylaxis to a bolus of antibiotic
c. Light planes of anesthesia
d. Hypothermia
e. Incorrect ET tube placement (as in a tube placed too distal to the carina)

A

D

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9
Q

Which of the following is associated with very deep plane 3, Stage III anesthesia?

a. Palpebral reflex briskly present
b. MAC awake
c. Jaw tone active
d. Eyes rolled ventrally
e. Eyes straight forward

A

E

sweet spot = eyeballs rotated ventral with more sclera visible

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10
Q

Two user friendly alternatives to EEG analysis used in human anesthesia monitoring, but sadly not as reliable in veterinary anesthesia monitoring, are

a. ECG and ETC02
b. BIS and Sp02
c. EMB and EMG
d. SCI and ECG
e. BIS and CSI

A

E

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11
Q

Which of the following is a measure of the partial pressure of oxygen dissolved in arterial plasma?

a. PaO2
b. PvO2
c. SpO2
d. SaO2
e. PPO2

A

A

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12
Q

Contractility is one factor in determination of ______, and is often monitored via an _______under anesthesia.

a. Sp02, pulse ox
b. Hb dissociation, ECG
c. Stroke volume, ECG
d. Sp02, capnography
e. Oxygen content, ECG

A

C

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13
Q

True or false: While bradycardia often indicates adequate to excessive planes of sedation/anesthesia, tachycardia can indicate either too much inhalant (excessive sedation/anesthesia) or too little inhalant.

A

TRUE

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14
Q

What are the 6 critical organs that get a majority of the heart’s output?

A
  1. liver
  2. kidneys*
  3. brain
  4. heart
  5. muscles
  6. skin
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15
Q

How are cardiac output and oxygen content calculated?

A

HR x stroke volume = CO (stroke volume = preload x contractility x afterload) OR BP/systemic vascular resistance

(Hb x 1.34 x SaO2) + (PaO2 x 0.003)

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16
Q

What are the major goals of judging depth of anesthesia?

A
  • assure lack of patient awareness, recall, pain, and movement
  • avoid excessive levels of cardiocerebrorespiratory depression, resulting in hypotension, hypothermia, and hypoventilation
  • maintain physiologic functions of the patient
  • use tools, but do not rely on them
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17
Q

What is required of the anesthetized state? Why is measuring depth hard?

A

unconsciousness and the lack of processing of perceptions, thoughts, and function

unconsciousness cannot be measured directly

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18
Q

How do non-invasive and invasive techniques of monitoring anesthesia depth compare?

A

NON-INVASIVE = little risk of complications, not as challenging, not as accurate

INVASIVE = higher risk of complications, technically challenging, more accurate, completely objective (direct BP catheterization)

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19
Q

How do subjective and objective non-invasive techniques of monitoring anesthesia depth compare?

A

SUBJECTIVE = no equipment needed; palpebral reaction

OBJECTIVE = equipment required; oscillometer BP

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20
Q

What information obtained from monitors are most useful?

A

trends —> one data piece is not completely indicative of the whole picture

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21
Q

What are common pitfalls in monitoring anesthetic depth?

A
  • depending only on one machine monitor or only machines
  • reacting to one reading
  • monitor without decision making (log data without reacting to data)
  • ignore common sense regarding patient care
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22
Q

What is the classical subjective test of anesthesia depth?

A

cranial nerves

  • like Goldilocks, helps decide if depth is adequate, too little, or too much and determine if our “cocktails” are adequate
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23
Q

Anesthesia stages:

A
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24
Q

What is indicative of a too light anesthesia depth? What 4 manual signs are observed? 3 vital parameters?

A

overt movement to surgical manipulation

  1. jaw tone tight or clamped
  2. eyes rolled straight forward
  3. pupils reactive
  4. palpebral response present

tachypnea, tachycardia and increased blood pressure

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25
Q

What 4 manual signs are observed in too deep anesthesia depth? 3 vital parameters?

A
  1. jaw tone lax
  2. eyes rolled straight forward
  3. pupils widely dilated or pinpoint
  4. no palpebral response

bradypnea/apnea, bradycardia, and low blood pressure

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26
Q

What are some anesthesia depth determinants?

A
  • amount of anesthesia in CNS
  • magnitude or surgical or external stimuli
  • preexisting discomfort, stress, and pain
  • underlying conditions that have CNS depressant effects: anesthesia (hypotension, hypothermia), comorbidities (Cushing’s, osteoarthritis), medications (enalapril, amlodipine, prednisone)
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27
Q

What signs of anesthesia depth commonly change first?

A

subjective/classic signs

  • monitoring variables change after and can indicate many things outside of depth, like ungrounded cautery, blood loss, and used sodasorb
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28
Q

What is the “sweet spot” of sedation depth? What are the 4 classic subjective signs?

A

Stage III, plane 2

  1. some jaw tone, “spring” present
  2. eyeballs rotated ventral, with more sclera visible
  3. palpebral not present or very weak
  4. pupils are mid-size and may be reactive
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29
Q

What are the ideal PR, RR, and BP found in Phase III, plane 2 of sedation?

A
  • PR = 50-120 (species and breed specific)
  • RR = under 20
  • BP = systolic 80-120
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30
Q

What 6 things are modified to alter depth and stage/plane of anesthesia?

A
  1. level of inhalant general anesthetic on vaporizer settings
  2. rates of intraoperative CRIs
  3. continued boluses of induction agents (propofol, alfaxalone)
  4. full or partial reversal of potent conscious sedation agents (dex, opioids)
  5. cardiovascular and respiratory control
  6. administration of other drugs
31
Q

What are the 4 stages to electroencephalographic monitoring?

A
  1. awake
  2. low amplitude, high frequency waves
  3. plane II = high amplitude, low frequency; plane III = burst suppression
  4. electrical silence
32
Q

What are 2 alternatives to EEG analysis?

A
  1. bispectral index (BIS) - quantified degree of anesthetic-induced cortical depression, ensuring patients are pain free and unaware
  2. cerebral state index (CSI) - collects EEG and EMG and calculates a numerical value for level of sedation
33
Q

What is the major problem with BIS monitoring? CSI? What is the major reason these are not used in veterinary anesthesia?

A

not all anesthetics affect BIS in the same way

CSI decreases with propofol, but doesn’t correlate with classic signs of depth in dogs; lacked discrimination for lighter planes

  • studies are equivocal on reliability based on breeds, species, and individuals
  • EEG parameters examine hypnotic changes, but not analgesia
  • $$$
34
Q

What cardiovascular variable have little to do with anesthesia depth and safety?

A

mucus membrane color and CRT —> circulation

35
Q

What are 6 possible causes of bradycardia under sedation or anesthesia?

A
  1. excessive inhalant anesthesia depth
  2. hypothermia
  3. anesthetic drugs
  4. increased vagal tone
  5. hypoglycemia
  6. mechanical ventilation
36
Q

What are 6 possible causes of tachycardia under sedation or anesthesia?

A
  1. pain, stress, inflammation (insufficient inhalant anesthesia)
  2. excessive inhalant anesthesia
  3. hemorrhage
  4. hypovolemia
  5. anesthetic drugs
  6. endocrine tumors
37
Q

When should bradycardia be corrected? What initial conservative steps can be taken?

A

when blood pressure is affected

  • check plane of anesthesia, adjust inhalant, oxygen flow, and CRI
  • warm patient
  • check for causes of increased vagal tone
  • check for hyperkalemia
  • change mechanical ventilation settings
38
Q

What class of drugs are used to help bradycardic patients under anesthesia? In what 4 situations are they used?

A

anticholinergic

  1. conservative fixes fail
  2. blood pressure fails
  3. vagal tone is excessive, common in ocular/CNS diseases and breeds
  4. pediatrics and neonates
39
Q

When are reversal agents used in bradycardic patients under anesthesia?

A
  • emergent care
  • anticholinergic fails

(be ready with rescue agents, the animal will hurt and be stressed)

40
Q

What is the difference between compensatory and primary tachycardia?

A

COMPENSATORY - adequate premed, proper dose of inhalant anesthesia, hemorrhage, drugs

PRIMARY = accompanied with arrythmia

41
Q

How does the dosage of inhalant anesthesia contribute to tachycardia?

A

TOO HIGH = vasodilation and compensatory tachycardia

TOO LOW = pain awareness and epinephrine release causes tachycardia

42
Q

What are the 3 major fixes to sinus tachycardia in a sedated patient?

A
  1. opioids: hydromorphone, methadone, oxymorphone, morphine, fentanyl (requires follow-up), pre-med opioid IV
  2. ketamine
  3. microdose of dexmedetomidine
43
Q

What is contractility? How is it monitored?

A

force and rhythm by which the heart expulses its preload against the body’s afterload (myosin, actin interaction)

ECG

44
Q

What is an arrhythmia? How are they monitored?

A

disturbance in rate, rhythm or site of cardiac impulse generation

ECG - surface recording of electrical activity of the myocardium using various electrodes

45
Q

What are the 3 initial steps to take when an arrhythmia is first noticed under anesthesia?

A
  1. palpate pulse and obtain a pulse rate
  2. establish plane of anesthesia (increased/reduce inhalant, administer opioids, sedatives, or anti-inflammatories)
  3. determine BP - fluid boluses, anticholinergics
46
Q

What are some causes of pulseless electrical activity (PEA)?

A
  • hypobolemia
  • hypoxia
  • hypothermia
  • hyperkalemia
  • pneumothorax
  • PE
  • tamponade
  • overdoses of anesthetics, antiarrhythmics, beta/alpha blockade, toxins
  • acidosis
  • acute myocardial infarction
47
Q

What are the expected normal and sedated pulse rates of kittens, cats, toy breeds/puppies, average-sized dogs, and giant breeds?

A
48
Q

What 4 drugs are used to treat sinus tachycardia in patients under anesthesia?

A
  1. ketamine
  2. morphine
  3. lidocaine
  4. propofol
49
Q

What is the sweet spot for intra-anesthetic BP in smaller and larger patients? When is hypotension and hypertension defined?

A

SMALL = 100-160; LARGE = 80-120

SMALL = < 80; LARGE = < 60

SMALL = > 150; LARGE = > 120

50
Q

How can anesthetics cause hypotension?

A

excessive anesthetic inhalant or CRI

51
Q

Why is central venous pressure not commonly utilized under anesthesia? What does it signify?

A

not a great predictor of cardiac output or depth

relationship between blood volume and blood volume capacity

52
Q

What is the normal central venous pressure of small animals?

A

in awake patients = 3-10 cm H20

53
Q

What patients are most prone to moderate-severe hypothermia?

A
  • smaller breeds
  • cats
  • alopecic
  • pediatric/neonatal
  • geriatric
  • low BCS
  • heavily premedicated
54
Q

What are the 3 ranges of hypothermia?

A
  1. 96-99F expected drop - immune function impaired, recovery not or mildly prolonged
  2. 90-96F moderate-severe drop - reduced anesthetic requirements, recovery prolonged
  3. 90-92F severe hypothermia - CO and cerebral metabolism reduced, myocardial automaticity increased, increased blood viscosity
55
Q

What is the most common cause of hypothermia under anesthesia and sedation? What are some other causes?

A

excessive inhalant or CRI depth

  • hypotension
  • high oxygen flow
  • open body cavities
  • cold fluids and flush
56
Q

What are the 2 most common causes of hyperthermia in anesthesia and sedation? What are some other causes?

A
  1. inadequate or light depth of anesthesia
  2. poor premedication
  • heavy har coat breeds
  • overzealous use of heat sources
  • low oxygen flows
  • inappropriate ET tubes
  • hypoventilation
  • inadequate CO2 waste removal
  • endocrine or neoplastic release
57
Q

How is hyperthermia under anesthesia treated?

A
  • increase oxygen flow
  • assure appropriate ET tube placement
  • reduce ET tube dead space
  • stop external heating devices
  • check capnography
58
Q

What are the normal respiratory rates of awake and anesthetized patients? When is bradypnea and tachypnea defined?

A

AWAKE = 10-30 bpm
ANESTHETIZED = 3-15 bpm, or 1/3 resting rate

  • bradypnea = 0-3 bmp
  • tachypnea = > 15 bmp
59
Q

What are the most common causes of bradypnea and tachypnea in anesthetized patients?

A

BRADYPNEA = excessive inhalant or CRI depth of anesthesia*, hypothermia, diaphragm or intercostal impairment, CNS or ocular pressure, gastric reflux or increased vagal tone

TACHYPNEA = pain, stress, anxiety, or inadequate depth of anesthesia

60
Q

What seems to be the most sensitive indicator of depth of anesthesia?

A

respiratory rate changes

61
Q

What are 4 reasons Doxapram is not given in cases of bradypnea in patients under anesthesia?

A
  1. use potentiates hypocapnia (CO2 is stimulus to breathing)
  2. hyperventilation is transient and often followed by apnea
  3. increases cerebral oxygen demand
  4. central stimulant
62
Q

What should be done in patients that are undergoing intraoperative wakening due to tachypnea?

A
  • give additional partial dose induction (“leftover” propofol, ketamine, valium, alfaxalone)
  • treat pain, stress, and inflammation with rescue medication
  • increase oxygen flow
  • increased vaporizer settings by 30-50%
63
Q

How does pulse oximetry and arterial blood gas analysis compare?

A

PULSE OX = SpO2; non-invasive, continuous, establishes pulse and oxygenation, safe, many variables can lead to poor readings

ART BLOOD GAS = SaO2, PaO2; invasive, intermittent, establishes respiration (oxygenation and ventilation), reliable for respiration, but says littler directly about cardiac output

64
Q

What are the ideal SpO2 levels in intubated and non-intubated patients?

A

INTUBATED = on 100% oxygen, >95-97% (>93% accepted due to technical error

NON-INTUBATED = on room air >90% is ideal; on oxygen supplementation >93% is expected

65
Q

What should be done if there is a low pulse ox reading?

A
  • INTUBATED = technical vs. non-respiratory
  • NOT INTUBATED = true hypoxia

~ TACHYCARDIC or TACHYPNEIC = true hypoxia
~ NOT = technical vs. non-respiratory

66
Q

What are the most common technical and non-respiratory causes of inconsistently low SpO2 readings?

A

TECHNICAL = insufficient inhalant or CRI depth, prob slipping, ambient lighting, probe compressing vessel

NON-RESPIRATORY = excessive inhalant or CRI depth, cold, wet, vasoconstricted

67
Q

What does PaO2 and SaO2 measure?

A

partial pressure of arterial oxygen dissolved in plasma —> ability of lungs to move oxygen from atmosphere to blood

hemoglobin saturation —> calculated value from blood gas results (commonly reduced in cats and horses)

68
Q

Why are SpO2, PaO2, and SaO2 not commonly as valuable for determining depth of anesthesia?

A
  • influenced by a lot of underlying components
  • 100% O2 is the carrier gas, so these levels are normally excellent in intubated patients
69
Q

What are the main 2 things end tidal concentrations are used to evaluate?

A
  1. circulation and perfusion
  2. respiratory and ventilation issues
70
Q

What are the 5 most common causes of decreasing ETCO2 readings and waveform height?

A
  1. hyperventilation
  2. dead space ventilation
  3. hypothermia
  4. hypovolemia
  5. vasoconstriction
71
Q

What is the most common cause of increasing ETCO2 readings and waveform height?

A
  • hypoventilation —> decreased CO2 removal
  • increased CO2 production —> hypermetabolism, malignant hyperthemia
72
Q

If other issues have been ruled out and there is a truly deep patient, what should be done?

A
  • flush the circuit
  • decrease vaporizer to 30-50%
  • keep oxygen flow the same or reduced by 30%
  • reduce or cease CRI
  • warm patient
73
Q

f other issues have been ruled out and there is a truly light patient, what should be done?

A
  • increase oxgyen flow (0.5-1 L/min) and vaporizer
  • use leftover induction agent IV bolus
  • check for leaks
  • give fluid bolus
  • rule out technical and nonsurgical discomfort
  • IV analgesia, sedative, and anti-inflammatory

Anesthesia (40 decks)

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