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Principles of Anesthesia I - Summer 24 > Clinical Monitoring 1 - Exam 1 > Flashcards

Clinical Monitoring 1 - Exam 1 Flashcards

1
Q

When would we have ventilatory pressure monitoring?

A
  • with invasive ventilation - LMA/ETT
  • Ex: PEEP/PIP
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2
Q

What pt population & surgeries require strict temp monitoring/thermoregulation?

A
  1. children & elderly
  2. major surgeries, long surgeries w/ temp changes
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3
Q

What does a Left shift in the oxyhemoglobin curve mean?

What 6 things cause a left shift in the oxyhemoglobin curve?

A
  • that Hb’s affinity for O2 is increased - not as much O2 released to tissues
    1. alkalosis (increased pH)
    2. Hypocarbia (low CO2)
    3. Hypothermia
    4. Decreased 2,3 DPG (metabolic byproduct)
    5. COHb
    6. Fetal Hb
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4
Q

What does a right shift in the oxyhemoglobin curve tell us?

What 4 things can cause a right shift?

A
  • Hb’s affinity for O2 is lower - O2 released easier & used by tissues
    1. Acidosis (low pH)
    2. Hypercarbia (high CO2)
    3. Hyperthermia
    4. Increased 2,3 DPG
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5
Q

O2 saturation of Hb

PO2 60mmHg = ____ O2 sat

A

90%

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6
Q

O2 saturation of Hb

PO2 40mmHg = ____ O2 sat

A

75%

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7
Q

O2 saturation of Hb

PO2 27mmHg = ____ O2 sat

A

50%

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8
Q

What 3 things happen to light as it goes through matter?

A
  1. transmitted
  2. absorbed
  3. reflected
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9
Q

What is the Beer-Lambert Law of Absorption?

A

relates transmission of light through a solution to concentration of solute

  • light absorption measured at wavelengths proportional to # of solutes
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10
Q

Beer-Lambert

What happens w/ low concentration Hb?

A
  • the solutes are not absorbing all of the wavelengths
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11
Q

Beer Lambert

What happens w/ high concentration Hb?

A

There are way less wavelengths getting through
* the concentrated solutes blocks most of the light

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12
Q

Beer-Lambert

What happens w/ less light path length? What is the example of this?

A
  • normal/constricted vessel - more light gets through
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13
Q

Beer-Lambert

What happens w/ more light path length? What is the example of this?

A
  • Dilated artery/vein - more light is absorbed & less gets through
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14
Q

What are the types of Hb that could be circulating in adult blood?

A
  1. Oxyhemoglobin
  2. Deoxyhemoglobin
  3. Methemoglobin (Fe3+)
  4. Carboxyhemoglobin
  5. Sulfhemoglobin
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15
Q

What is Sulfhemoglobin?

A
  • stable green pigment molecule
  • made through oxidation of iron in Hb from sulfa containing drugs
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16
Q

What type of oximetry is the gold standard for measuring carboxyhemoglobin?

A

Co-oximetry
* regular pulse-ox demonstrates falsely elevated O2 sat

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17
Q

Wavelength Chart

A
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18
Q

Red light wavelengths

A

660nm

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19
Q

Infrared light wavelengths

A

940nm

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20
Q

Deoxyhemogobin (deO2Hb) absorbs more ____ light.

A

Red light (660nm)

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21
Q

Oxyhemoglobin (O2Hb) absorbs more ____ light.

A

Infrared (940nm)

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22
Q

What estimates SaO2?

A

pulsatility of arterial blood flow

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23
Q

What is pulse-ox light transmitted through?

A
  1. Skin
  2. soft tissue
  3. venous blood
  4. arterial blood
  5. capillary blood
  • different tissue/solutes
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24
Q

What is the ratio of AC/DC light absorption?

A

the pulsatile component divided by the non-pulsatile component for each wavelength

  • the more tissue your pt has or the more vasodilated = more light absorption
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25
Q

What is DC?

A

Direct current
* non-pulsatile
* deO2Hb

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26
Q

What is AC?

A

Alternating Current
* pulsatile
* O2Hb

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27
Q

Carboxyhemoglobin vs. Oxyhemoglobin

A

COHb absorbs as much light in 660nm (red) range as O2Hb

  • falsely elevated SpO2
  • Left shift in O2Hb curve - less release of O2
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28
Q

Each ____ increase in COHb will increase SpO2 by ____.

What % COHb do smokers have?

A
  1. 1% - 1%
  2. > 6% in smokers (6% falsely high SpO2)
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29
Q

What 6 things can interfere w/ the pulse-ox read out?

A
  1. Ambient light
  2. Low perfusion (low CO, shock, vasoconstricted)
  3. Venous blood pulsations = altered AC (pulsatile)
  4. Additional light absorbers (methylene blue)
  5. Additional forms of Hb (fetal Hb, COHb)
  6. Nail Polish
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30
Q

When would you have pulsatile venous blood flow?

A
  1. infant - transposition of great vessels
  2. alteration in R heart return
  3. AV fistulas
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31
Q

What types of surgeries would methylene blue be administered?

A
  1. Renal cases
  2. Cysto cases
  3. bladder cases
    • in ICU for other indications (vasoplegia)
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32
Q

What happens w/ a pulse-ox reading in response to methylene blue admin?

A
  • falsely low until methylene blue circulates & gets out of system
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33
Q

Pulse-ox and CO measurement

A
  • pulse ox may indicate CO status
  • looks like A-line waveform = GREAT CO
  • Dampened = POOR CO

look for trends

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34
Q

Where is a good spot to place a pulse-ox in someone w/ an epidural?

A

On their toes - vasodilated w/ epidural

35
Q

Why should a pulse-ox not be placed on the index finger?

A
  • when pts wake up they stab themselves in the eye (corneal abrasion)
36
Q

What areas of the body are less affected by vasoconstriction and will reflect desaturation quicker?

A
  1. Tongue, Cheek, Forehead
37
Q

What produces korotkoff sounds?

A
  • turbulent flow beyond the partially occluded cuff
38
Q

Korotkoff Sounds

Phase I:
Phase II:
Phase III:
Phase IV:
phase V:

A
  1. most turbulent/audible (SBP)
  2. softer & longer
  3. crisper & louder
  4. softer & muffled
  5. sounds disappear (DBP)
39
Q

Formula for MAP

A

MAP = DBP + 1/3(SBP-DBP)

40
Q

What are 5 limitations to BP Auscultation?

A
  1. decreased peripheral flow
  2. changes in vessel compliance (edema, atherosclerosis)
  3. incorrect cuff size
  4. obesity
  5. kids
41
Q

Appropriate Cuff Bladder

A
  • 40% of arm circumference
  • 80% length of upper arm
  • center over the artery
42
Q

Automatic BP

What BP measurement has the least agreement w/ invasive BP monitor?

A

SBP
* esp. in critically ill/elderly

43
Q

What conditions produce errors w/ automatic BP monitoring?

A
  1. atherosclerosis (low SBP & high DBP = narrowed PP)
  2. edema
  3. obesity
  4. chronic HTN
44
Q

BP cuff size & BP measurement
cuff too large =
cuff too small =

A

large = low BP
small = high BP

45
Q

BP machines - problems w/ estimation

A
  • underestimate MAP during HTN
  • overestimate MAP during HoTN
  • underestimate SBP/overestimate DBP
46
Q

Possible complications of automatic BP measurement

A
  1. Compartment Syndrome
  2. Pain (Raynaud’s)
  3. Peteichiae/ecchymoses
  4. limb edema
  5. Venous stasis & thrombophlebitis
  6. peripheral neuropathy
47
Q

When should we use caution w/ automatic BP?

A
  1. severe coagulopathies
  2. peripheral neuropathies
  3. arterial/venous insufficiency
  4. recent thrombolytics
48
Q

What are 4 indications for invasive BP monitoring?

A
  1. continuous, real time measurement needed
  2. planned pharmacologic manipulation
  3. repeated blood sampling
  4. determination of volume responsiveness
49
Q

Monitoring sites for invasive BP monitoring

A
  1. Radial: most common
  2. Ulnar
  3. Brachial: impedance of flow
  4. Axillary
  5. Femoral - hidden hematoma
  6. Posterior Tibial
  7. Dorsalis pedis
50
Q

How to perform Allen’s Test:

A
  1. occlude radial & ulnar arteries
  2. pt makes a fist - exsanguination of palm
  3. release of ulnar artery
    • color should return in seconds
  5. poor predictive value!
51
Q

Seldinger’s Technique for A-line insertion

A
  1. Prop the wrist on a towel & tape fingers back
    - 30-45 degree angle
  2. go in w/ needle
  3. thread guidewire
  4. remove needle
  5. place cath & take guidewire out
52
Q

Transfixion Technique for A-line placement

A
  • same positioning & prep as Seldinger’s
    1. front & back walls punctured intentionally
    2. needle removed
    3. needle removed
    4. cath withdrawn until pulsatile blood flow appears - then advanced
53
Q

What anatomic location is the A-line leveled at?

A

Aortic root

54
Q

What 3 things can we do to maximize the A-line waveform?

A
  1. limit stopcocks
  2. limit tubing length
  3. non-distensible tubing
55
Q

What is 1 labeling?

A

Systolic Upstroke
* right after the R wave in EKG

56
Q

What is 2 labeling?

A

Systolic peak pressure

57
Q

What is 3 labeling?

A

Systolic Decline

58
Q

What is 4 labeling?

A

Dicrotic notch (aortic valve closing)

59
Q

What is 5 labeling?

A

Diastolic runoff - valves are closed & blood is running back in

60
Q

What is 6 labeling?

A

End-Diastolic Pressure

61
Q

What will the arterial waveform look like closer to the aortic arch?

Further from the aortic arch?

A
  • closer - more crude
  • Further (pedal/femoral) - more smooth
62
Q

Characteristics as arterial pressure wave moves to periphery

A
  1. arterial upstroke steeper
  2. systolic peak higher
  3. dicrotic notch later (Aortic Valve)
  4. End-diastolic pressure lower
63
Q

How are arterial pressure waveforms made?

A
  • summation of sine waves
  • fundamental wave + harmonic wave = arterial pressure wave
    6 - 10 harmonics needed for most arterial pressure waves
64
Q

________ ________ is analysis of the summation of multiple sine waves and gives us the projection on the screen.

A

Fourier Analysis

65
Q

Arterial Waveform

What does a distinct dicrotic notch suggest?

A

the system has good resolution @ higher frequencies
* not overdamped

66
Q

Arterial Waveform

How many oscillations should follow after a fast flush in the square wave test?

A
  • no more than 2
  • amplitude should be no greater than 1/3 of previous oscillation
  • time interval b/w the 2 <30msec = 33Hz
67
Q

What is an underdamped arterial waveform?

A
  • multiple oscillations after fast flush
  • SBP overestimated
  • several dicrotic notches
68
Q

What is an overdamped arterial waverform?

A
  • pressure tracing does not oscillate after fast flush
  • dicrotic notch lost
  • SBP decreased & falsely narrowed PP
69
Q

Arterial BP monitoring

What 5 things can cause Pressure Gradient Changes

A
  1. age (less compliance = SBP higher & DBP lower = increased PP)
  2. atherosclerosis
  3. peripheral vascular resistance changes
  4. septic shock
  5. hypothermia
70
Q

What are 5 possible Arterial line complications?

A
  1. distal ischemia/pseudoaneurysm
  2. hemorrhage/hematoma
  3. arterial line emboli
  4. local infection
  5. peripheral neuropathy
71
Q

What is the purpose of pressure waveform analysis?

A

to identify the presence of residual preload reserve
* assess to see if pts will tolerate a fluid bolus

72
Q

What does pressure waveform analysis look at?

A

cyclic arterial BP variations d/t respiratory induced changes in intrathoracic pressure

73
Q

BP changes w/ PPV

A
  • BP goes up on inspiration (increased LV preload and decreased LV afterload)
  • BP goes down on expiration (LV preload reduced b/c decreased venous return)
74
Q

What is Systolic Pressure Variation (SPV) looking at?

A

cycle of increasing & decreasing SV and arterial BP in response to end-expiratory pressure

75
Q

Normal SPV (swing) in mechanically vented pts

76
Q

Normal change up in SPV (inspiration)

77
Q

Normal change down in SPV (swing) - expiration

78
Q

what is increased SPV indicative of?

A

The pt will be volume responsive or have residual preload reserve

  • critically ill - dramatic increase in SPV is usually from the down component (> 5-6mmHg)
79
Q

What is PPV (pulse pressure variation) looking at?

A
  • maximum and minimum pulse pressures over the entire respiratory cycle
  • also assess fluid status of the pt (high is dry)
80
Q

What is normal PPV?

A

< 13-17%

b/w 13-17% or > will have positive response to vol. expansion

PPV 14% = give volume

81
Q

SVV (stroke volume variation) correlates ________ and ________ based on age and gender.

A
  1. resistance
  2. compliance
82
Q

Formula for SVV =

A

SVV = (SV max - SV min)/SV mean

83
Q

SVV normal

A

10-13%
* > 10-13% positive response to volume expansion

84
Q

What 6 things are necessary to have an accurate assessment of BP variation?

A
  1. mechanical ventilation (Vt 8-10mL/kg)
  2. PEEP > or = 5mmHg
  3. regular cardiac rhythm
  4. normal intra-abdominal pressure (closed cavity)
  5. Closed chest
  6. pt positioning

Principles of Anesthesia I - Summer 24 (15 decks)

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