Monitoring the Anesthetized and Critically Ill Patient Flashcards

1
Q

what are indicators of anesthetic depth (4)

A
  1. movement
  2. physiological measures: HR/resp rate
  3. eye: reflexes, position
  4. jaw tone
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2
Q

how can the eye be used to determine the depth of anesthesia (5)

A
  1. eye rotates ventro-medially
  2. palpebral reflex abolished
  3. corneal reflex abolished
  4. eye rotates centrally
  5. pupil dilates (too deep)
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3
Q

how can the respiratory rate be used to determine the anesthetic depth

A

the resp rate is a poor indicator of respiratory adequacy

CO2 levels are better

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4
Q

why is feeling the pulse preferable during anesthesia

A

can assess heart rate, rhythm, pulse quality/strength to give indication of peripheral perfusion

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5
Q

do good pulses equal good blood pressure

A

pulse pressure is the difference between systolic and diastolic blood pressure and doesn’t reflect absolute values

a full pulse generally implies an adequate blood pressure –> but not always

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6
Q

what monitors can be used to assess respiratory parameters

A

pulse oximetry

capnography

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7
Q

what monitors can be used for CVS

A
  1. ECG
  2. blood pressure
  3. urine output
  4. central venous pressure
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8
Q

what does pulse oximetry measure

A

SpO2

% saturation of hemoglobin with oxygen

pulse rate

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9
Q

where can pulse oximetry sensor be placed

A
  1. tongue
  2. nail bed
  3. ear tip
  4. vulva/prepuce
  5. lip fold
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10
Q

what is blood gas analysis

A

PaO2

partial pressure of oxygen dissolved in plasma

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11
Q

what does SpO2 tell us

A

it should be above 90% in animals breathing room air

and

above 95% in anesthetized animals breathing 100% oxygen

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12
Q

why might the pulse oximetry reading be reliable (9)

A
  1. pigmented skin
  2. movement (heavy breathing)
  3. compression of vascular bed
  4. ambient light
  5. poor contact
  6. peripheral vasoconstriction (medetomidine)
  7. low blood pressure
  8. pulsatile veins (tricuspid regurgitation)
  9. abnormal hemoglobins (carboxyhemoglobin, methemoglobin)
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13
Q

how do you assess the signal quality of pulse oximetry

A

all should have some way of assessing the signal quality

flashing light, etc

only belive the reading if you are satisfied with the signal

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14
Q

what can cause low SpO2 (4)

A
  1. low inspired oxygen
  2. lung disease (V/Q mismatch & diffusion impairement)
  3. R to L shunting
  4. hypoventilation (although not on oxygen supplementation)
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15
Q

what are the causes of low inspired oxygen which would cause low SpO2 (4)

A
  1. disconnection
  2. incorrect gas mixture (100% N2O)
  3. kinked tube
  4. airway obstruction
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16
Q

what lung diseases can cause low SpO2 (5)

A
  1. pneumonia (aspiration)
  2. pneumothorax
  3. pulmonary edema
  4. pulmonary embolus
  5. bronchoconstriction (asthma)
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17
Q

what R to L shunting can cause low SpO2

A

congential heart disease (patent ductus, septal defects, tetralogy of fallot)

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18
Q

what is cyanosis

A

blue colouring of arterial blood when deoxyhemoglobin is present

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19
Q

what is the SpO2 monitor more sensitive in detecting - cyanosis or desaturation

A

desaturation

cyanosis may never occur in some patients (anemic)

cyanosis is very subjective

20
Q

what are the limitations of pulse oximetry (3)

A
  1. getting reliable readings
  2. doesn’t tell you about perfusion/blood pressure
  3. doesn’t tell you anything about CO2 levels (SpO2 of 100% when on >40% oxygen doesn’t mean the animal is breathing adequately)
21
Q

what is capnography

A

monitors

  1. respiratory function
  2. detects breathing system/ETT malfunction and other problems
  3. gives some indications of CO
22
Q

where is a capnography monitor placed

A

at end of ETT

23
Q

what are the types of capnographs (2)

A
  1. mainstream: analyzer actually placed at end of tube
  2. sidestream: gas is sampled down a sampling line to a distant monitor
24
Q

what information does capnography give (4)

A
  1. resp rate
  2. EtCO2
  3. inspired CO2
  4. the trace
25
describe the capnography trace
26
what is the normal value of EtCO2 for dogs
4.6-6 kPa (35-45mmHg)
27
what is the EtCO2
in animals with normal lungs it is an approximation of arterial CO2 partial pressure its directly linked to the minute volume
28
what occurs to the EtCO2 during hypoventilation
increases
29
what occurs to the EtCO2 during hyperventilation
decreases
30
what EtCO2 value is action required
8.0 kPa (60mmHg) hypoventilation is common under anesthesia --\> most commonly due to the anesthetic depth
31
what can the capnograph traces tell you (5)
1. kinked ETT/blocked ETT/bronchoconstriction 2. rebreathing of CO2 (problem with anesthetic breathing system) 3. bucking the ventilator 4. disconnection 5. CV collapse (cardiac arrest/severe hypotension)
32
what does ECG measure
electrical activity of the heart continuous measure of heart rate and rhythm easy and non-invasive to apply
33
what are the advantages of ECG
1. detects arrhythmias 2. identify cardiac rhythm in CPR
34
what can arrhythmias result in (4)
1. electrolyte imbalance 2. cardiac disease 3. systemic disease (shock) 4. traumatic
35
what are the disadvantages of ECG (3)
1. no indication of adequate CO and perfusion to tissues 2. can be normal with severe hypovolemia or hypoperfusion 3. can even be normal when the heart is not beating (pulseless electrical activity)
36
how is blood pressure calculated
cardiac output x total peripheral resistance
37
what should the systolic, mean BP and diastolic values in animals be
systolic: \>90 mmHg mean BP: \>60 mmHg diastolic: \>40 mmHg
38
what is an oscillometric technique to collect BP
cuff placed over a peripheral artery that occludes blood flow in the limb and senses oscillations
39
what peripheral arteries can you use for oscillometric BP
1. metatarsal 2. ulnar 3. tail
40
what are the oscillations that detect BP (3)
1. start at systolic BP 2. are maximal at mean BP 3. disappear at diastolic BP
41
what size of the oscillometric cuff be
width should be 40-60% of the limb diameter
42
what does the oscillometric technique not measure well (4)
1. arrhythmias 2. severe hypotension 3. vasoconstriction 4. movement
43
what is the doppler technique to measure BP
ultrasonic probe placed over peripheral artery gives a continuous audible signal a proximally placed cuff is inflated until the sound disappears the sound returns at systolic BP (mean BP in anesthetized cats)
44
what should normal urine output be
1-2 ml/kg/hr
45
what does urine output indicate
good renal perfusion
46
what is central venous pressure
pressure measured in vena cava via a transducer/manometer connected to a central venous cannula measures an indirect measure of cardiac preload useful to detect volume overload in patients with cardiac disease
47
what is normal central venous pressure value
0-10 cmH2O