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APEX > Unit 6 - Hemodynamic Monitors & Equipment > Flashcards

Unit 6 - Hemodynamic Monitors & Equipment Flashcards

1
Q

what do Korotkoff sounds represent

A

turbulent flow in an artery that was previously occluded by the BP cuff

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2
Q

BP auscultation

A
  • relies on korotkoff sounds
  • SBP is measured at the first sound
  • DBP is measured when the last sound disappears
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3
Q

what is cuff pressure when korotkoff sounds are produced

A

between SBP and DBP

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4
Q

how do NIBP machines measure BP

A

Oscillatory Method

Inflatable cuff occludes arterial blood flow, and as the cuff pressure is released, the monitor measures the pressure fluctuations that occur in response to arterial pulsations

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5
Q

when is SBP measured with oscilattory method

A

when oscillations 1st appear (the reappearance of flow after cuff occlusion)

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6
Q

when is DBP measured with oscillatory method

A

measured at the minimum pressure where oscillations can still be generated

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7
Q

BP measurement reading that’s the most susceptible to error with oscillatory method

A

DBP

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8
Q

why won’t NIBP work in a pt on CPD or with LVAD

A

requires pulsatile flow

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9
Q

ideal bladder length for BP cuff

A

80% of extremity circumference

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10
Q

ideal bladder width of NIBP cuff

A

40% of extremity circumference

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11
Q

NIBP reading with a cuff that’s too small

A

overestimates SBP

cuff pressure required to occlude artery is higher

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12
Q

NIBP reading when cuff is too large

A

underestimates SBP

cuff pressure required to occlude artery is lower

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13
Q

what happens to SBP, DBP, and pulse pressure measurements as pulse moves from aortic root toward periphery

A

SBP increase
DBP decrease
PP widens

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14
Q

SBP, DBP, and PP at aortic root

A

SBP lowest, DBP highest, PP narrowest

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15
Q

SBP, DBP, and pulse pressure at radial artery compared to aortic root

A

SBP higher
DBP lower
PP wider

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16
Q

BP reading if BP cuff above heart

A

BP reading falsely decreased (less hydrostatic pressure)

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17
Q

BP reading if cuff below heart

A

BP reading falsely increased (more hydrostatic pressure)

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18
Q

every 10 cm change in BP cuff above/below heart = BP changes by _____

A

7.4 mmHg

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19
Q

Complications of NIBP Measurement

A
  • pain
  • neuropathy (radial, ulnar, median)
  • measurement errors
  • limb ischemia
  • compartment syndrome
  • bruising
  • petechiae
  • interference with IV medications
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20
Q

what is measured at the peak of art line waveform

A

SBP

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21
Q

what is measured at the trough of art line waveform

A

DBP

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22
Q

what does the upstroke of art line waveform represent

A

contractility

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23
Q

what part of arterial line waveform represents stroke volume

A

area under curve

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24
Q

where does art line monitor BP

A

at level of transducer (not at site of catheter insertion)

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25
Q

art line transducer location that won’t be affected by changes in body or extremity position

A

level of RA

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26
Q

causes of falsely increased NIBP

A
  • BP cuff too small
  • BP cuff too loose
  • Bp measured on extremity below level of heart
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27
Q

causes of falsely decreased NIBP

A
  • BP cuff too large
  • cuff deflated too rapidly
  • measured on extremity above level of heart
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28
Q

measurement that remains constant throughout arterial tree

A

MAP

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29
Q

where does art line pressure have the greatest pulse pressure

A

dorsalis pedis

SBP increases along arterial tree as a function of pressure waves reflec

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30
Q

where is arterial DBP measurement lowest

A

dorsalis pedis

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31
Q

what does optimal waveform morphology balance

A

amount of damping with amount of distortion from transducer system

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32
Q

High-pressure flush test (square test):

A

shows how fast the system vibrates in response to a pressure signal

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33
Q

what informs about damping characteristics in art line system

A

number of oscillations after flush test

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34
Q

when is an art line considered optimally damped

A

baseline is re-established after 1 oscillation

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35
Q

when is art line waveform considered under damped

A

baseline re-established after several oscillations

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36
Q

BP measurements with under damped art line

A

SBP overestimated, DBP underestimated, MAP accurate

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37
Q

causes of underdamped art line

A
  • stiff (non-compliant) tubing
  • catheter whip (artifact)
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38
Q

when is an art line system considered over damped

A

baseline re-established with no oscillations

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39
Q

BP measurements in overdamped art line system

A

SBP underestimated, DBP overestimated, MAP accurate

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40
Q

causes of overdamped art line system

A
  • air bubble in pressure tubing
  • clot in catheter
  • low flush bag pressure
  • kinks
  • loose connection
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41
Q

how does dicrotic notch change with art line monitoring location

A

moves further away from systolic peak the further the monitoring site is from the heart

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42
Q

where should CVL tip rest

A

just above the junction of vena cava & right atrium

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43
Q

risks assoc. with CVL catheter in heart chambers

A

↑ risk dysrhythmias, thrombus formation, cardiac perforation

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44
Q

where should pulmonary artery catheter tip be

A
  • in the pulmonary artery, distal to pulmonic valve
  • 25-35 cm from VC junction
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45
Q

3 steps to calculate distance of CVL insertion

A
  1. Know the distance from site of entry to VC junction
  2. Know distance from VC junction to where catheter tip should be (only applies if placing PAC)
  3. Add these 2 numbers together to determine distance from site of insertion to catheter tip
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46
Q

distance from subclavian vein to junction of vena cava and RA

A

10 cm

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47
Q

distance from right IJ to junction of vena cava and RA

A

15 cm

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48
Q

distance from left IJ to junction of vena cava and RA

A

20 cm

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49
Q

distance from femoral vein to junction of vena cava and RA

A

40 cm (either side)

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50
Q

distance from median basilic vein to junction of vena cava and RA

A

right = 40 cm
left = 50 cm

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51
Q

distance from vana cava/RA junction to RA

A

0-10 cm

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52
Q

distance from vena cava/RA junction to RV

A

10-15 cm

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53
Q

distance from vena cava/RA junction to PA

A

15-30 cm

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54
Q

distance from vana cava/RA junction to where PAOP is measured

A

25-35 cm

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55
Q

what should you assume if PAC advanced 10 cm past calculated distance and expected waveform still isn’t seen

what should you do?

A

catheter is coiled

  • Deflate balloon, withdraw catheter to junction of VC and RA, try again
  • If resistance encountered when pulling back catheter is possibly knotted or entangled with chordae tendineae  obtain CXR to r/o
56
Q

possible complications while obtaining CVL access

A
  • arterial puncture
  • PTX
  • air embolism
  • neuropathy
  • catheter knot
  • dysrhythmias (most common)
57
Q

The best way to treat PACs/PVCs with CVL insertion

A

withdraw catheter and start over

58
Q

complications assoc with floating PAC

A

PA rupture, RBBB, dysrhythmias

59
Q

risks of left IJ CVL

A

risk of puncturing thoracic duct
can cause chylothorax (lymph in chest)

60
Q

when does risk of CVL infection increase

A

3 days after placement

61
Q

classic presentation of PA rupture

A

hemoptysis

62
Q

factors that increase risk of PA rupture with PAC placement

A
  • anticoagulation
  • hypothermia
  • advanced age
  • inserting catheter too far
  • prolonged balloon inflation
  • chronic irritation of vessel wall
  • unrecognized wedging
  • filling balloon with liquid instead of air
63
Q

what does the CVP waveform represent

A

pressure inside RA

64
Q

components of CVP waveform

A
  • 3 peaks (a, c, v)
  • 3 troughs (x,y)
65
Q

mechanical and electrical events associated with A wave of CVP waveform

A
  • mechanical: RA contraction
  • electrical: just after P wave (atrial depolarization)
66
Q

mechanical and electrical events associated with C wave of CVP waveform

A
  • mechanical: RV contraction (bulging of tricuspid into RA)
  • electrical: just after QRS (ventricular depolarization)
67
Q

mechanical and electrical events associated with x descent of CVP waveform

A
  • mechanical: RA relaxation
  • electrical: ST segment
68
Q

mechanical and electrical events associated with V wave of CVP waveform

A
  • mechanical: passive RA filling
  • electrical: just after T wave begins (ventricular repolarization)
69
Q

mechanical and electrical events associated with Y descent of CVP waveform

A
  • mechanical: RA empties through open tricuspid valve
  • electrical: after T wave ends
70
Q

where should CVP be zeroed

A

at phlebostatic axis

71
Q

CVP reading if transducer is above or below phlebostatic axis

4th intercostal space mid anteroposterior level

A
  • Transducer above = underestimates CVP
  • Transducer below = overestimates CVP
72
Q

during which part of respiratory cycle should CVP be measured & why

A

end-expiration
* During this phase of ventilatory cycle, extravascular pressure = atmospheric pressure
* Allows CVP measurement relative to atmospheric pressure

73
Q

intersection between vascular function curve and CO curve

A

CVP

74
Q

normal CVP value

A

1-10 mmHg

75
Q

3 things CVP is a function of

A
  1. intravascular volume
  2. venous tone
  3. RV compliance
76
Q

causes of an increased CVP reading

A
  • transducer below phlebostatic axis
  • hypervolemia
  • RV failure
  • tricuspid stenosis/regurg
  • pulmonic stenosis
  • PEEP
  • VSD
  • constrictive pericarditis
  • cardiac tamponade
77
Q

causes of decreased CVP reading

A

transducer above phlebostatic axis, hypovolemia

78
Q

what causes loss of a wave in CVP waveform

A
  • occurs when priming function of the RA is lost
  • A fib, V-pacing if underlying rhythm is asystole
79
Q

causes of large a wave in CVP waveform

A

atrium contracts & empties against high resistance (either valve or non-compliant vent.)
* Tricuspid stenosis
* diastolic dysfunction
* myocardial ischemia
* chronic lung disease - RVH
* AV dissociation
* junctional rhythm
* V pacing (asynchronous)
* PVCs

80
Q

causes of large v wave in CVP waveform

A
  • tricuspid regurg - allows a portion of RV volume to pass through closed but incompetent tricuspid valve during RV systole
  • acute increase in intravascular volume
  • RV papillary muscle ischemia
81
Q

CVP waveform with tricuspid regurg

A
  • large v wave
  • c and v waves may blend into each other
82
Q

normal RA pressure

A

1-10 mmHg

same as CVP

83
Q

normal RA pressure

A

1-10 mmHg

same as CVP

84
Q

normal RV pressure

A

15-30 / 0-8

85
Q

normal PA pressure

A

15-30 / 5-15

86
Q

normal PAOP

A

5-15 mmHg

87
Q

when is the dictrotic notch formed in PAP waveform

A

during pulmonic valve closure during diastole

88
Q

where should tip of PAC be

A

in lung zone 3

89
Q

where is this waveform measured

A

right atrium

90
Q

where is this waveform measured

A

right ventricle

91
Q

where is this waveform measured

A

pulmonary artery

92
Q

what does this waveform represent

A

PAOP

93
Q

why should PAC tip be in West lung zone 3

A

Continuous column of blood between tip of PAC and LV in this region

94
Q

where is west zone 3 located when:
* sitting
* supine
* prone
* lateral

A
  • Sitting = lung base
  • Supine = towards back
  • Prone = towards chest
  • Lateral = dependent lung
95
Q

when does PAC placement give the most accurate estimation of LVEDP

A

when tip placed in West zone 3

96
Q

relationship between Pa, PA, and Pv in West zone 3

A

Pa > Pv > PA

97
Q

things that suggest the PAC tip is NOT in zone 3

A
  • PAOP > PA end-diastolic pressure
  • Nonphaseic PAOP tracing
  • Inability to aspirate blood from distal port when balloon in wedged position
98
Q

things that cause PAOP to overestimate LVEDP

for given PAOP, true volume in LV is less than predicted by PAOP

A
  • Impaired LV compliance (ischemia)
  • Mitral valve disease (stenosis or regurg)
  • L - R cardiac shunt
  • Tachycardia
  • PPV, PEEP
  • COPD
  • Pulmonary HTN
  • Misplaced
99
Q

what does it mean for a PAOP to overestimate LVEDP

A

for given PAOP, true volume in LV is less than predicted by PAOP

100
Q

how does aortic valve insufficiency affect PAOP measurement

A

will underestimate LVEDV

101
Q

when does thermodilution underestimate CO

A

injectate too much or too cold

102
Q

when does thermodilution overestimate CO

A

injectate volume too low or hot, partially wedged PAC, thrombus on PAC top

103
Q

method to improve accuracy of thermodilution CO measurement

A

Common practice to average 3 separate injections to arrive at final CO (improves accuracy)

104
Q

how is CO measured via thermodilution

A
  • 5% dextrose or 0.9% NaCl of known quantity and temp bloused through proximal port of PAC
  • Each injection should be in same phase of respiratory cycle and completed in < 4 seconds
105
Q

used to calculate and plot temp change vs. time to determine CO

A

Modified Stewart-Hamilton equation

106
Q

significant drawback of continuous CO monitoring (COO)

A

30-second delay between time measured and time seen on monitor

107
Q

CCO value averages data over what time frame

A

3-6 minutes

108
Q

SVO2 calculation and normal values

A
109
Q

SvO2 is a function of what 4 variables

A
  1. Q = Cardiac output (L/min)
  2. VO2 = Oxygen consumption (mL O2/min)
  3. Hgb = Amount of hemoglobin (g/dL)
  4. SaO2 = Loading of hemoglobin in arterial blood (%)
110
Q

when does SvO2 become an indirect monitor of CO

A

Hgb, SaO2 and VO2 held constant

111
Q

conditions associated with decreased SvO2

A

O2 consumption increases or O2 delivery decreases
* ↑ O2 consumption: stress, pain, thyroid storm, shivering, fever, light anesthesia
* ↓ O2 delivery: ↓ PaO2, ↓ Hgb (anemia), ↓ CO

112
Q

conditions that increase SvO2

A

O2 consumption decreases or O2 delivery increases
* ↓ O2 consumption: hypothermia, cyanide toxicity
* ↑ O2 delivery: ↑ PaO2, ↑ Hgb, ↑ CO

113
Q

how does sepsis affect SvO2

A
  • increases
  • creates high CO state with arterial admixture
  • O2 bypasses tissues
114
Q

classic example of increased SvO2 d/t impaired O2 uptake by tissues

A

cyanide poisoning from Nipride

115
Q

how does a L-R shunt affect SvO2

A

increases
oxygenated blood travels from L to R heart, added to pulmonary venous blood

116
Q

where can a true mixed venous sample be collected

A

pulmonary artery

must contain blood from SVC, IVC, and coronary sinus

117
Q

CO is a function of what 3 factors

A
  1. preload
  2. contractility
  3. afterload
118
Q

how does pulse contour analysis allow for accurate fluid balance assessment

A

by providing more precise measures of fluid responsiveness, O2 delivery, and microcirculatory flow

119
Q

what is pulse pressure variation calculated from

A

arterial waveform measures max and min pulse pressure values throughout respiratory cycle

percentage change is called pulse pressure variation

120
Q

Pulse contour analysis provides a measure of:

A

preload responsiveness as a function of how stroke volume changes during respiratory cycle (assumes PPV)

121
Q

as a general rule, when is preload responsiveness assumed

A

when 200-250 mL fluid bolus improves SV > 10%

122
Q

dynamic measures of pulse contour

A

PVI, SVV, SPV, PPV

123
Q

when do dynamic measures of pulse contour tend to predict volume responsiveness

A

when calculated measurement is > 13-15%

124
Q

why will a hypovolemic patient have a greater degree of SV variation throughout respiratory cycle

A

as a function of intrathoracic pressure’s effect on RV filling and function

125
Q

things that can cause errors in contour analysis

A
  • SV
  • small Vt
  • PEEP
  • open chest
  • RV dysfunction
  • dysrhythmias
126
Q

gold standard for assessing myocardial function

A

TEE

127
Q

where should tip of esophageal doppler probe be

A

~35 cm from incisors (T5-T6 or at 3rd sternocostal junction)

128
Q

how does esophageal doppler give information about fluid status

A

Emits ultrasound beam towards descending aorta & reflects off the blood traveling through it
* By measuring aortic diameter and blood’s velocity through descending aorta, can derive several useful variables to guide fluid management

129
Q

limitations to esophageal doppler use

A

aortic stenosis, aortic insufficiency, disease of thoracic aorta, aortic cross-clamping, after CPB, pregnancy

130
Q

esophageal doppler contraindication

A

Esophageal disease is a relative contraindication

131
Q

what does a wave represent in PAOP waveform

A

LA systole

132
Q

what does c wave represent in PAOP waveform

A

mitral valve elevation into LA during LV systole/RV contraction (isovolumetric contraction)

133
Q

what does v wave represent in PAOP waveform

A

passive LA filling

134
Q

PAOP is an estimate of:

A

LVEDP

135
Q

events associated with a wave of CVP waveform

A
  • atrial systole
  • ventricular diastole
136
Q

Best TEE view for LV ischemia

A

midpapillary muscle level in shot axis

APEX (54 decks)

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