Anesthesiology Lecture 6 Monitoring Anesthesia

Front 1

What are the 4 purposes of monitoring anesthesia?

Back 1

1) Assess depth of anesthesia
2) Assess response to anesthesia
3) Verify performance of equipment
4) Improve safety

Front 2

In general, what variables of anesthesia do you want to monitor?

Back 2

Variables that respond quickly to change in anesthetic depth

Front 3

When monitoring you are assessing normal VS abnormal values for what 2 things?

Back 3

1) Vital signs in that specie
2) Responses to anesthetic drug administration

Front 4

What are the 3 organ systems being monitored during anesthesia? What do you assess for each system?

Back 4

1) CNS
-assess depth of anesthesia
2) Cardiovascular
-assess adequacy of perfusion
3) Respiratory
-Assess ventilation/ oxygenation

Front 5

How do we assess ventilation?

Back 5

By monitoring how well the animal is eliminating CO2

Front 6

What are 10 parameters that we monitor during anesthesia regarding the cardiovascular system?

Back 6

1) HR
2) ECG
3) Pulse rate
4) Pulse pressure
5) Membrane color
6) Perfusion time
7) BP
8) Pulse oximetry
9) Central venous pressure
10) CO

Front 7

What are 3 methods used to monitor the HR?

Back 7

1) Auscultation w/ stethescope, if thorax accessible, or esophageal stethoscope
2) Palpate peripheral pulse
3) Monitor ECG
-lets you know rate & rhythm

Front 8

What are 2 types of leads used to monitor the ECG?

Back 8

Lead II
Base-apex lead

Front 9

Compare the heart rate of larger breeds and smaller breeds.

Back 9

Larger breeds are slower
Smaller breeds are faster

Front 10

Do juveniles have a faster or slower heart rate?

Back 10

Faster

Front 11

True or false. Heart rate is usually unaffected by premedication and anesthesia depth during small animal surgery.

Back 11

False, affected by premedicants used and depth of anesthesia can affect HR (insufficient anesthesia= increased HR)
e.g. Dexmetatomidine & opioids slow HR

Front 12

What are 6 arteries that can be paplpated to measure the pulse in canine/felines?

Back 12

1) Dorsal pedal
2) Femoral
3) Lingual
4) Coccygeal
5) Metacarpal
6) Metatarsal

Front 13

What is the normal heart rate of dogs under anesthesia?

Back 13

65-180 beats / minute
-alpha2 will slow HR to 40 or 50 so he'll use a lower dose

Front 14

What is the normal heart rate of a cat under anesthesia?

Back 14

100-220 beats/minute
-alpha2 will slow HR to 40 or 50 so he'll use a lower dose

Front 15

When does the depth of anesthesia affect HR in SMALL ANIMALS?

Back 15

Usually won't decrease as depth of anesthesia increases, but can increase if depth of anesthesia is insufficient

Front 16

Out of horses, ruminants, camelids and swine, which has the slowest HR?

Back 16

Horses

Front 17

How does the HR fluctuate with anesthesia in LARGE ANIMAL surgery?

Back 17

HR may decrease as depth increases (except in horses)

Front 18

What are 6 arteries that can be palpated to measure the pulse in a horse?

Back 18

1) Facial
2) Digital
3) Radial
4) Dorsal metatarsal
5) Transverse facial
6) Caudal auricular

Front 19

What is the normal heart rate of an adult horse under anesthesia? Juveniles?

Back 19

Adults: 30-50 beats/min
Juveniles: 50-70 beats/min

Front 20

What are 4 arteries that can be palpated to measure the HR in ruminants?

Back 20

1) Common digital
2) Caudal auricular
3) Saphenous
4) Radial

Front 21

What is the normal HR of an adult ruminant under anesthesia? Juvenile?

Back 21

Adult: 70-100 beats/min
Juveniles: 80-120 beats/min

Front 22

What are 4 arteries you can palpate to measure the HR in a camelid?

Back 22

1) Common digital
2) Caudal auricular
3) Radial
4) Saphenous
*Same as ruminants

Front 23

What is the normal HR for an adult camelid under anesthesia? Juveniles?

Back 23

Adults: 60-90 beats/min (w/ atropine)
28-40 beats/min (w/ alpha2)
Juveniles: 90-125 beats/min

Front 24

What are the 3 arteries that can be palpated to measure the heart rate in swine?

Back 24

1) Radial
2) Caudal auricular
3) Saphenous

Front 25

What is the normal HR for adult swine under anesthesia? Juveniles?

Back 25

Adults: 60-90 beats/min
Juveniles: 90-125 beats/min

Front 26

What are the 3 characteristics of the pulse that you should analyze?

Back 26

Strength, rate, rhythm

Front 27

What determines the pulse pressure?

Back 27

Difference b/w systolic and diastolic pressure
e.g. 120/90 mmHg palpates similar to 90/60 mmHg

Front 28

True or false. Pulse strength gives a pretty accurate quantitative estimate of BP.

Back 28

False, not accurate

Front 29

When examining a pressure wave, what is a dicrotic notch? Is it a good thing?

Back 29

Blood is ejected from aorta and then blood starts to flow backwards towards the heart, then the valves closes and blood hits the valve and squirts forward again
-it appears as the second bump on graph

Front 30

What is the only difference b/w the arteries palpated to estimate HR and pulse strength among all the species (as in which arteries can be palpated)?

Back 30

All of them are the same, but in swine you can also palpate the dorsal pedal artery to estimate pulse strength

Front 31

What color should mucous membranes be?

Back 31

Pink, not pale or cyanotic

Front 32

What is required for an animal to be ABLE to have cyanotic mucous membranes?

Back 32

Requires AT LEAST 5 g of hemoglobin

Front 33

Perfusion time is an indicator of ______.

Back 33

Blood pressure

Front 34

When you blanche a gum, what is a normal capillary refill time?

Back 34

<2 seconds
-be careful, "perfusion time" can be close to normal after death bc just squish blood out and it flows back

Front 35

What instrumentation is used to assess the electrical activity of the heart?

Back 35

Electrocardiography (ECG)

Front 36

Electrocardiography allows continuous audible assessment of the _____ and _____ of the heart.

Back 36

Rate & rhythm

Front 37

What are 2 downfalls of electrocardiography?

Back 37

1) May not correlate w/ mechanical activity
2) Artifacts can be common

Front 38

What type of leads are most commonly used for electrocardiography?

Back 38

Lead II
Modified base-apex lead

Front 39

What are 2 locations where you can put the left arm lead of an ECG?

Back 39

Left thorax
Base of heart

Front 40

Where do you put the right arm lead when using electrocardiography in animals?

Back 40

Right thorax

Front 41

Where do you put the left leg lead when performing electrocardiography?

Back 41

Patient's head or throat
-Change lead selector to find one that will be accurate

Front 42

What are 2 measuring devices used for arterial catheterization?

Back 42

1) Aneroid manometer
-instrument used to measure pressure
2) Long fluid administration set

Front 43

What are the 4 electrical instruments used for direct blood pressure?

Back 43

1) Transducer
2) Amplifier
3) Display
4) Anderoid manometer
-or long fluid administration set

Front 44

When directly measuring blood pressure with arterial catheterization is is ________, continuous and inaudible.

Back 44

Accurate

Front 45

Direct blood pressure measurements can be altered by position of the ________.

Back 45

Transducer

Front 46

What are 4 sites used for arterial catheterization?

Back 46

1) Dorsal pedal
2) Coccygeal
3) Femoral
4) Lingual
-All these are also used to check pulse

Front 47

What are 5 sites used for arterial catheterization in horses?

Back 47

1) Facial
2) Transverse facial
3) Dorsal metatarsal
4) Digital
5) Caudal auricular
-All these are also used to check pulse

Front 48

What are 4 sites used for arterial catheterization in ruminants and camelids?

Back 48

1) Common digital
2) Caudal auricular
3) Saphenous
4) Radial

Front 49

What are 3 sites used for arterial catheterization in swine?

Back 49

1) Caudal auricular
2) Saphenous
3) Radial

Front 50

What are 2 methods used to indirectly measure blood pressure?

Back 50

1) Doppler
-Return to flow principle
2) Oscillometric technic
-Cardell series & others OR petmap

Front 51

What does the Doppler measure?

Back 51

Determines blood flow & determines systolic pressure
-Value nearer mean pressure in cats/small dogs

Front 52

Dopplers produce a continuous audible signal of ______ and ______, but not ________.

Back 52

Continuous audible signal of RATE and RHYTHM, but not PRESSURE.

Front 53

What are 3 parameters that we can control that can cause errors in a Doppler reading?

Back 53

1) Faulty probe placement
2) Incorrect cuff size
3) Rapid cuff deflation

Front 54

What are 4 physiologic parameters of the patient that can result in errors in a Doppler reading?

Back 54

1) Hypotension
2) Hypovolemia
3) Bradycardia
4) Hypothermia

Front 55

What are 4 arteries that the crystal can be placed on when using a Doppler?

Back 55

1) Metacarpal
2) Metatarsal
3) Dorsal pedal
4) Tail (less often)

Front 56

What does the Doppler measure?

Back 56

Determines blood flow & determines systolic pressure
-Value nearer mean pressure in cats/small dogs

Front 57

Dopplers produce a continuous audible signal of ______ and ______, but not ________.

Back 57

Continuous audible signal of RATE and RHYTHM, but not PRESSURE.

Front 58

What are 3 parameters that we can control that can cause errors in a Doppler reading?

Back 58

1) Faulty probe placement
2) Incorrect cuff size
3) Rapid cuff deflation

Front 59

What are 4 physiologic parameters of the patient that can result in errors in a Doppler reading?

Back 59

1) Hypotension
2) Hypovolemia
3) Bradycardia
4) Hypothermia

Front 60

What are 4 arteries that the crystal can be placed on when using a Doppler?

Back 60

1) Metacarpal
2) Metatarsal
3) Dorsal pedal
4) Tail (less often)

Front 61

What are 4 arteries the crystal can be placed on when using a doppler on a horse?

Back 61

1) Tail
2) Dorsal metatarsal
3) Digital
4) Radial

Front 62

What are 3 arterial the crystal probe of a Doppler can be placed on in a camelid, ruminant or swine?

Back 62

1) Tail
2) Common digital
3) Radial

Front 63

Do you want to place the crystal distal or proximal to the cuff when using a Doppler?

Back 63

Proximal to crystal

Front 64

How do you know what size of a cuff to use when measuring blood pressure with a Doppler?

Back 64

Cuff diameter should be 40% of circumference of limb

Front 65

What are the benefits of the Cardell series and others?

Back 65

Accurate over a wider range of heart rates and patient sizes.

Front 66

What are 5 errors/physiologic changes that can result in inaccurate blood pressure measurements when using a Cardell series?

Back 66

1) Hypotension
2) Hypovolemia
3) Hypothermia
4) Bradycardia
5) Wrong cuff

Front 67

**What does the cardell measure?

Back 67

Determines mean arterial pressure and calculates systolic and diastolic pressure and HR

Front 68

When does the cardell take measurements (at what intervals)?

Back 68

Some will cycle at user-determined intervals, automated, very convenient and usually accurate

Front 69

True or false. Non-invasive blood pressure is a continuous method, that is not audible and can be inaccurate.

Back 69

False, It is inaudible and can be inaccurate, but not continuous

Front 70

What are 3 locations that the cardell series can be used on to take the blood pressure of a small animal?

Back 70

1) Metatarsus
2) Antebrachium
3) Tail

Front 71

What are 4 sites you can use for a Cardell series to measure blood pressure in a horse?

Back 71

1) Tail
2) Dorsal metatarsal
3) Digital
4) Radial

Front 72

What are 3 sites blood pressure can be taken using a Cardell series in a ruminant, camelid and swine?

Back 72

1) Tail
2) Common digital
3) Radial

Front 73

What is the normal blood pressure (systolic, diastolic and MAP) of a dog?

Back 73

Systolic: 80-120 mmHg
Diastolic: 40-80 mmHg
Mean: 60-100 mmHg

Front 74

What is the normal blood pressure of a cat?

Back 74

Systolic: 80-150 mmHg
Diastolic: 40-80 mmHg
Mean: 60-120 mmHg

Front 75

What is the normal blood pressure a horse?

Back 75

Systolic: 95-120 mmHg
Diastolic: 65-90 mmHg
Mean: 75-100 mmHg

Front 76

Why do horses require a higher mean arterial pressure compared to other species?

Back 76

When animal is down and putting weight on the muscles and if too deep then the driving pressure to force open those capillaries is diminished so get areas of ischemia and if get enough muscle damage then horse can't stand afterward
-Keep MAP> 75 to prevent myopathy

Front 77

What is the normal blood pressure of sheep, goat, camelids and swine?

Back 77

Systolic: 80-100 mmHg
Diastolic: 50-70 mmHg
Mean: 60-80 mmHg

Front 78

What is the normal blood pressure of cattle?

Back 78

Systolic: 120-150 mmHg
Diastolic: 75-100 mmHg
Mean: 90-120 mmHg

Front 79

Why are indirect blood pressure readings inaccurate with camelids?

Back 79

Because on cannon bone its just bone so the algorithms aren't designed for this

Front 80

Is pulse oximetry invasive? continuous? audible?

Back 80

Noninvasive
Continuous
Audible

Front 81

How does pulse oximetry measure hemoglobin saturation?

Back 81

Utilizes red & infrared light to determine hemoglobin saturation

Front 82

What does pulse oximetry display?

Back 82

Waveform & heart rate

Front 83

What is the normal percent saturation of hemoglobin?

Back 83

SpO2> 95%

Front 84

Why is pulse oximetry useful during anesthesia?

Back 84

Detects hypoxemia before cyanosis is present

Front 85

What are 4 sources of error when using pulse oximetry?

Back 85

1) Motion
2) Ambient light
3) Vasoconstriction
-hypothermia, hypovolemia, drug induced
4) Dyshemoglobinemia

Front 86

What is the primary site used to get pulse oximetry readings?

Back 86

Tongue

Front 87

What are some alternate sites used for pulse oximetry (not tongue)?

Back 87

Nares in some species, paw, ear, prepuce, vulva
-*alternate locations need white skin
-achilles tendon less dependable

Front 88

What does the central venous pressure assess?

Back 88

Venous return to right atrium/ heart's ability to pump

Front 89

What is a normal central venous pressure?

Back 89

5-10 cm H2O for most species
-Normal can be 20-30 cm H20 in equines in lateral recumbency

Front 90

True or false. Central venous pressure can be a big help during anesthesia.

Back 90

False, little use during anesthesia

Front 91

What are 4 ways to monitor/measure cardiac output?

Back 91

1) Thermodilution
2) Dye dilution
3) Lithium dilution
4) Ultrasound techniques

Front 92

True or false. Cardiac output is not commonly monitored in clinical cases.

Back 92

True

Front 93

What is dye dilution?

Back 93

Inject dye into right atrium or anterior vena cava and then measure concentration and calculate out dilution
-but background concentrations kept increasing w/ time

Front 94

What is thermodilution?

Back 94

Inject saline and then measure temperature, use pulmonary arterial catheter

Front 95

What is lithium dilution?

Back 95

Don't need a pulmonary arterial catheter like you do w/ thermodilution, just inject lithium and then push button and blood is aspirated out of artery and then computer tells you concentration and CO

Front 96

What are 3 ways to monitor the respiratory system (without electronic equipment)?

Back 96

1) Auscultation
2) Observation of chest excursions
3) Observe breathing pattern
-movement of rebreathing bag, chest wall, abdomen

Front 97

What are 4 parameters that are measured to monitor the respiratory system?

Back 97

1) Tidal volume
2) Capnography
3) Blood gas analysis
4) Rate

Front 98

Abdominal breathing is common in what 3 situations/animals?

Back 98

1) large animals
2) Neonates
3) When obstruction or lung disease is present

Front 99

How is respiratory rate affected by anesthetic depth?

Back 99

Rate tends to decrease as anesthetic depth increases

Front 100

What is the normal respiratory rate in a dog?

Back 100

8-15 breaths/min

Front 101

What is the normal respiratory rate of a cat?

Back 101

10-20 breaths/min

Front 102

How does panting affect anesthesia intake?

Back 102

results in less effective ventilation

Front 103

What is the normal respiratory rate of horses?

Back 103

6-8 breaths/ min

Front 104

What is the normal respiratory rate of a ruminant?

Back 104

25-40 breaths/min

Front 105

What is the normal respiratory rate of a camelid?

Back 105

10-20 breaths/min

Front 106

What is the normal respiratory of swine?

Back 106

10-20 breaths/min

Front 107

______ "pant" under anesthesia.

Back 107

Ruminants

Front 108

How do you assess tidal volume?

Back 108

Watching rebreathing bag, not very precise
-rebreathing bag should move in sync with chest

Front 109

How is tidal volume affected by anesthetic depth?

Back 109

Tends to decrease as anesthetic depth increases

Front 110

How do you measure tidal volume?

Back 110

Spirometer
- but tidal volume changes rapidly so can't really measure it

Front 111

What is the normal tidal volume in canines/felines?

Back 111

8-10 mL/kg

Front 112

What is the normal tidal volume of a horse?

Back 112

8-12 mL/kg

Front 113

What is the tidal volume of a ruminant?

Back 113

5-8 mL/kg

Front 114

How does the tidal volume vary between the ventilator and the volume the animal naturally breathes in?

Back 114

Ventilator is higher amount

Front 115

What is one way to assess ventilation during anesthesia?

Back 115

Capnography- measures CO2 in expired gas
-CO2 goes up the less the animal breathes

Front 116

How does the depth of anesthesia affect CO2 levels?

Back 116

PCo2 will increase as depth of anesthesia increases or with increased doses of opioids

Front 117

What can be used to detect equipment malfunction? what types of malfunction?

Back 117

Capnography
-Recognizes airway disconnection, apnea, abnormal breathing patterns and cardiac arrest (blood flow ceases and no CO2 returns to lungs so decreases very quickly)

Front 118

How does partial pressure of end tidal carbon dioxide vary from partial pressures of arterial CO2?

Back 118

PetCO2 < PaCO2 by 10-15 torr

Front 119

What is the normal partial pressure of end tidal CO2?

Back 119

40-75 torr (spon Vent)
30-35 torr (IPPV)

Front 120

What is the normal fractional concentration of inspired O2? inspired CO2?

Back 120

FIO2= 50-90%
FICO2< 2 torr

Front 121

What does it mean if the fractional concentration of inspired CO2 increases?

Back 121

Sodalyme is running out

Front 122

What are 3 things that can be analyzed using blood gas analysis?

Back 122

1) Acid-base status
2) Adequacy of ventilation & oxygenation
3) Many assess electrolytes, lactate, glucose

Front 123

What is the normal PaCO2 for large animals using Spon Vent? Small animals?

Back 123

Large animals: 60-75 torr
Small animals: 40-60 torr
-both using spon vent

Front 124

What is the normal PaCO2 using IPPV ?

Back 124

40-45 torr

Front 125

What is the normal PaO2 in small animals? Large animals?

Back 125

Small animals: 400-500 torr
Large animals: > 200 torr

Front 126

What is a normal pH?

Back 126

7.35-7.45

Front 127

What are 6 ways to check the CNS status of a patient under anesthesia?

Back 127

1) Muscle relaxation/ jaw tone
2) Ocular reflexes/ eye position
3) Lacrimation
4) Laryngeal/ swallowing reflex
5) Response to pain/ pedal reflex (to assess response to pain or surgical stimulus)
6) Ear flick/ whisker reflex

Front 128

How do you assess muscle relaxation? What animals is it useful in?

Back 128

By jaw tone
-Useful reflex in dogs and cats
-some tone should be present

Front 129

What does a lack of jaw tone in a dog or cat imply?

Back 129

Depth of anesthesia can be decreased

Front 130

How can you monitor the ocular reflexes in a dog?

Back 130

Globe begins centrally then as gets deeper in anesthesia the eye moves rostral-ventral ("rolled in")

Front 131

How do you monitor the ocular reflexes in a bovine?

Back 131

As depth of anesthesia increases the globe roles ventrally, then as anesthesia levels out the globe moves dorsally to the center

Front 132

What is the palpebral reflex?

Back 132

Lids close when touched or lid margins brushed

Front 133

Palpebral reflexes are slow to absent in what animal?

Back 133

Horses

Front 134

What does it mean if the palpebral reflex is present in any animal other than a horse?

Back 134

Means insufficient anesthesia

Front 135

What is the corneal reflex? Should it be present during anesthesia?

Back 135

Lids should close when cornea is touched, should be present

Front 136

What is a nystagmus?

Back 136

Medial-lateral oscillations of eye

Front 137

What does the presence of nystagmus in a HORSE imply?

Back 137

Anesthesia is too light
-best accuracy in horses, other species not dependable

Front 138

How is pupillary dilation/ constriction affected by anesthesia?

Back 138

-Pupil may dilate slightly during induction (excitement) then may constrict
-pupils dilate at increasing depth

Front 139

Lacrimation is an indirect indicator of _______ pressure, which is useful in horses.

Back 139

Perfusion pressure

Front 140

When is the swallowing reflex present during anesthesia?

Back 140

Lost early and regained just prior to return of consciousness
-can be present in ruminants at adequate depth of anesthesia

Front 141

Why should the swallowing reflex be present at the time of extubation?

Back 141

To prevent aspiration

Front 142

What is the laryngeal reflex?

Back 142

Closure of arytenoid cartilages due to tactile stimulation
-can make intubation difficult

Front 143

Laryngeal reflex is more common in what 4 animals?

Back 143

Cats, goats, sheep & swine

Front 144

What is the cause of laryngospasm in cats?

Back 144

A sustained laryngeal reflex

Front 145

How do we assess an animal's response to pain? How is this helpful for monitoring anesthesia?

Back 145

Pedal reflex: pinch pad or digit, lack of withdrawal when depth adequate

Front 146

What does the ear flick/ whisker reflex indicate?

Back 146

Inadequate anesthetic depth

Front 147

What does increased heart rate, respiratory rate, and blood pressure indicate?

Back 147

Insufficient depth

Front 148

How do we perform anesthetic agent analysis?

Back 148

Measures end tidal agent concentration to provide an estimate of dose, interpretation affected by premedication, local anesthesia

Front 149

Most surgeries are done at _____-_____ MAC, if the animal is premedicated ____-_____ MAC is used and if an epidural is in place _____-____ MAC is usually required.

Back 149

1.25-1.5 MAC
1.0-1.25 (w/ premed)
<1 MAC (epidural)

Front 150

What are 5 ways to asses fluid balance?

Back 150

1) Hematocrit or hemoglobin
2) Electrolytes (Na, K, Cl, Ca)
3) Plasma total solids or serum total protein
4) Glucose, lactate
5) Urine production

Front 151

What are 2 ways to monitor body temperature during surgery?

Back 151

1) Clinical thermometer
2) Esophageal or rectal probe

Front 152

What does increased heart rate, respiratory rate, and blood pressure indicate?

Back 152

Insufficient depth

Front 153

How do we perform anesthetic agent analysis?

Back 153

Measures end tidal agent concentration to provide an estimate of dose, interpretation affected by premedication, local anesthesia

Front 154

Most surgeries are done at _____-_____ MAC, if the animal is premedicated ____-_____ MAC is used and if an epidural is in place _____-____ MAC is usually required.

Back 154

1.25-1.5 MAC
1.0-1.25 (w/ premed)
<1 MAC (epidural)

Front 155

What are 5 ways to asses fluid balance?

Back 155

1) Hematocrit or hemoglobin
2) Electrolytes (Na, K, Cl, Ca)
3) Plasma total solids or serum total protein
4) Glucose, lactate
5) Urine production

Front 156

What are 2 ways to monitor body temperature during surgery?

Back 156

1) Clinical thermometer
2) Esophageal or rectal probe

Front 157

What are 4 risks that increase in a patient that's hypothermic?

Back 157

1) Arrhythmias
2) Blunts response to chronotropes
3) Delays recovery
4) Increases risk of infection at surgical site