Unit 6 - Hemodynamic Monitors & Equipment Flashcards
(136 cards)
1
Q
what do Korotkoff sounds represent
A
turbulent flow in an artery that was previously occluded by the BP cuff
2
Q
BP auscultation
A
- relies on korotkoff sounds
- SBP is measured at the first sound
- DBP is measured when the last sound disappears
3
Q
what is cuff pressure when korotkoff sounds are produced
A
between SBP and DBP
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
5
Q
when is SBP measured with oscilattory method
A
when oscillations 1st appear (the reappearance of flow after cuff occlusion)
6
Q
when is DBP measured with oscillatory method
A
measured at the minimum pressure where oscillations can still be generated
7
Q
BP measurement reading that’s the most susceptible to error with oscillatory method
A
DBP
8
Q
why won’t NIBP work in a pt on CPD or with LVAD
A
requires pulsatile flow
9
Q
ideal bladder length for BP cuff
A
80% of extremity circumference
10
Q
ideal bladder width of NIBP cuff
A
40% of extremity circumference
11
Q
NIBP reading with a cuff that’s too small
A
overestimates SBP
cuff pressure required to occlude artery is higher
12
Q
NIBP reading when cuff is too large
A
underestimates SBP
cuff pressure required to occlude artery is lower
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
14
Q
SBP, DBP, and PP at aortic root
A
SBP lowest, DBP highest, PP narrowest
15
Q
SBP, DBP, and pulse pressure at radial artery compared to aortic root
A
SBP higher
DBP lower
PP wider
16
Q
BP reading if BP cuff above heart
A
BP reading falsely decreased (less hydrostatic pressure)
17
Q
BP reading if cuff below heart
A
BP reading falsely increased (more hydrostatic pressure)
18
Q
every 10 cm change in BP cuff above/below heart = BP changes by _____
A
7.4 mmHg
19
Q
Complications of NIBP Measurement
A
- pain
- neuropathy (radial, ulnar, median)
- measurement errors
- limb ischemia
- compartment syndrome
- bruising
- petechiae
- interference with IV medications
20
Q
what is measured at the peak of art line waveform
A
SBP
21
Q
what is measured at the trough of art line waveform
A
DBP
22
Q
what does the upstroke of art line waveform represent
A
contractility
23
Q
what part of arterial line waveform represents stroke volume
A
area under curve
24
Q
where does art line monitor BP
A
at level of transducer (not at site of catheter insertion)
25
art line transducer location that won't be affected by changes in body or extremity position
level of RA
26
causes of falsely increased NIBP
* BP cuff too small
* BP cuff too loose
* Bp measured on extremity below level of heart
27
causes of falsely decreased NIBP
* BP cuff too large
* cuff deflated too rapidly
* measured on extremity above level of heart
28
measurement that remains constant throughout arterial tree
MAP
29
where does art line pressure have the greatest pulse pressure
dorsalis pedis
| SBP increases along arterial tree as a function of pressure waves reflec
30
where is arterial DBP measurement lowest
dorsalis pedis
31
what does optimal waveform morphology balance
amount of damping with amount of distortion from transducer system
32
High-pressure flush test (square test):
shows how fast the system vibrates in response to a pressure signal
33
what informs about damping characteristics in art line system
number of oscillations after flush test
34
when is an art line considered optimally damped
baseline is re-established after 1 oscillation
35
when is art line waveform considered under damped
baseline re-established after several oscillations
36
BP measurements with under damped art line
SBP overestimated, DBP underestimated, MAP accurate
37
causes of underdamped art line
* stiff (non-compliant) tubing
* catheter whip (artifact)
38
when is an art line system considered over damped
baseline re-established with no oscillations
39
BP measurements in overdamped art line system
SBP underestimated, DBP overestimated, MAP accurate
40
causes of overdamped art line system
* air bubble in pressure tubing
* clot in catheter
* low flush bag pressure
* kinks
* loose connection
41
how does dicrotic notch change with art line monitoring location
moves further away from systolic peak the further the monitoring site is from the heart
42
where should CVL tip rest
just above the junction of vena cava & right atrium
43
risks assoc. with CVL catheter in heart chambers
↑ risk dysrhythmias, thrombus formation, cardiac perforation
44
where should pulmonary artery catheter tip be
* in the pulmonary artery, distal to pulmonic valve
* 25-35 cm from VC junction
45
3 steps to calculate distance of CVL insertion
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
46
distance from subclavian vein to junction of vena cava and RA
10 cm
47
distance from right IJ to junction of vena cava and RA
15 cm
48
distance from left IJ to junction of vena cava and RA
20 cm
49
distance from femoral vein to junction of vena cava and RA
40 cm (either side)
50
distance from median basilic vein to junction of vena cava and RA
right = 40 cm
left = 50 cm
51
distance from vana cava/RA junction to RA
0-10 cm
52
distance from vena cava/RA junction to RV
10-15 cm
53
distance from vena cava/RA junction to PA
15-30 cm
54
distance from vana cava/RA junction to where PAOP is measured
25-35 cm
55
what should you assume if PAC advanced 10 cm past calculated distance and expected waveform still isn't seen
what should you do?
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
possible complications while obtaining CVL access
* arterial puncture
* PTX
* air embolism
* neuropathy
* catheter knot
* **dysrhythmias** (most common)
57
The best way to treat PACs/PVCs with CVL insertion
withdraw catheter and start over
58
complications assoc with floating PAC
PA rupture, RBBB, dysrhythmias
59
risks of left IJ CVL
risk of puncturing thoracic duct
can cause chylothorax (lymph in chest)
60
when does risk of CVL infection increase
3 days after placement
61
classic presentation of PA rupture
hemoptysis
62
factors that increase risk of PA rupture with PAC placement
* 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
what does the CVP waveform represent
pressure inside RA
64
components of CVP waveform
* 3 peaks (a, c, v)
* 3 troughs (x,y)
65
mechanical and electrical events associated with A wave of CVP waveform
* mechanical: RA contraction
* electrical: just after P wave (atrial depolarization)
66
mechanical and electrical events associated with C wave of CVP waveform
* mechanical: RV contraction (bulging of tricuspid into RA)
* electrical: just after QRS (ventricular depolarization)
67
mechanical and electrical events associated with x descent of CVP waveform
* mechanical: RA relaxation
* electrical: ST segment
68
mechanical and electrical events associated with V wave of CVP waveform
* mechanical: passive RA filling
* electrical: just after T wave begins (ventricular repolarization)
69
mechanical and electrical events associated with Y descent of CVP waveform
* mechanical: RA empties through open tricuspid valve
* electrical: after T wave ends
70
where should CVP be zeroed
at phlebostatic axis
71
CVP reading if transducer is above or below phlebostatic axis
| 4th intercostal space mid anteroposterior level
* Transducer above = underestimates CVP
* Transducer below = overestimates CVP
72
during which part of respiratory cycle should CVP be measured & why
end-expiration
* During this phase of ventilatory cycle, extravascular pressure = atmospheric pressure
* Allows CVP measurement relative to atmospheric pressure
73
intersection between vascular function curve and CO curve
CVP
74
normal CVP value
1-10 mmHg
75
3 things CVP is a function of
1. intravascular volume
2. venous tone
3. RV compliance
76
causes of an increased CVP reading
* transducer below phlebostatic axis
* hypervolemia
* RV failure
* tricuspid stenosis/regurg
* pulmonic stenosis
* PEEP
* VSD
* constrictive pericarditis
* cardiac tamponade
77
causes of decreased CVP reading
transducer above phlebostatic axis, hypovolemia
78
what causes loss of a wave in CVP waveform
* occurs when priming function of the RA is lost
* A fib, V-pacing if underlying rhythm is asystole
79
causes of large a wave in CVP waveform
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
causes of large v wave in CVP waveform
* 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
CVP waveform with tricuspid regurg
* large v wave
* c and v waves may blend into each other
82
normal RA pressure
1-10 mmHg
| same as CVP
83
normal RA pressure
1-10 mmHg
| same as CVP
84
normal RV pressure
15-30 / 0-8
85
normal PA pressure
15-30 / 5-15
86
normal PAOP
5-15 mmHg
87
when is the dictrotic notch formed in PAP waveform
during pulmonic valve closure during diastole
88
where should tip of PAC be
in lung zone 3
89
where is this waveform measured
right atrium
90
where is this waveform measured
right ventricle
91
where is this waveform measured
pulmonary artery
92
what does this waveform represent
PAOP
93
why should PAC tip be in West lung zone 3
Continuous column of blood between tip of PAC and LV in this region
94
where is west zone 3 located when:
* sitting
* supine
* prone
* lateral
* Sitting = lung base
* Supine = towards back
* Prone = towards chest
* Lateral = dependent lung
95
when does PAC placement give the most accurate estimation of LVEDP
when tip placed in West zone 3
96
relationship between Pa, PA, and Pv in West zone 3
Pa > Pv > PA
97
things that suggest the PAC tip is NOT in zone 3
* PAOP > PA end-diastolic pressure
* Nonphaseic PAOP tracing
* Inability to aspirate blood from distal port when balloon in wedged position
98
things that cause PAOP to overestimate LVEDP
| for given PAOP, true volume in LV is less than predicted by PAOP
* Impaired LV compliance (ischemia)
* Mitral valve disease (stenosis or regurg)
* L - R cardiac shunt
* Tachycardia
* PPV, PEEP
* COPD
* Pulmonary HTN
* Misplaced
99
what does it mean for a PAOP to overestimate LVEDP
for given PAOP, true volume in LV is less than predicted by PAOP
100
how does aortic valve insufficiency affect PAOP measurement
will underestimate LVEDV
101
when does thermodilution underestimate CO
injectate too much or too cold
102
when does thermodilution overestimate CO
injectate volume too low or hot, partially wedged PAC, thrombus on PAC top
103
method to improve accuracy of thermodilution CO measurement
Common practice to average 3 separate injections to arrive at final CO (improves accuracy)
104
how is CO measured via thermodilution
* 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
used to calculate and plot temp change vs. time to determine CO
Modified Stewart-Hamilton equation
106
significant drawback of continuous CO monitoring (COO)
30-second delay between time measured and time seen on monitor
107
CCO value averages data over what time frame
3-6 minutes
108
SVO2 calculation and normal values
109
SvO2 is a function of what 4 variables
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
when does SvO2 become an indirect monitor of CO
Hgb, SaO2 and VO2 held constant
111
conditions associated with decreased SvO2
O2 consumption increases or O2 delivery decreases
* ↑ O2 consumption: stress, pain, thyroid storm, shivering, fever, light anesthesia
* ↓ O2 delivery: ↓ PaO2, ↓ Hgb (anemia), ↓ CO
112
conditions that increase SvO2
O2 consumption decreases or O2 delivery increases
* ↓ O2 consumption: hypothermia, cyanide toxicity
* ↑ O2 delivery: ↑ PaO2, ↑ Hgb, ↑ CO
113
how does sepsis affect SvO2
* increases
* creates high CO state with arterial admixture
* O2 bypasses tissues
114
classic example of increased SvO2 d/t impaired O2 uptake by tissues
cyanide poisoning from Nipride
115
how does a L-R shunt affect SvO2
increases
oxygenated blood travels from L to R heart, added to pulmonary venous blood
116
where can a true mixed venous sample be collected
pulmonary artery
must contain blood from SVC, IVC, and coronary sinus
117
CO is a function of what 3 factors
1. preload
2. contractility
3. afterload
118
how does pulse contour analysis allow for accurate fluid balance assessment
by providing more precise measures of fluid responsiveness, O2 delivery, and microcirculatory flow
119
what is pulse pressure variation calculated from
arterial waveform measures max and min pulse pressure values throughout respiratory cycle
percentage change is called pulse pressure variation
120
Pulse contour analysis provides a measure of:
preload responsiveness as a function of how stroke volume changes during respiratory cycle (assumes PPV)
121
as a general rule, when is preload responsiveness assumed
when 200-250 mL fluid bolus improves SV > 10%
122
dynamic measures of pulse contour
PVI, SVV, SPV, PPV
123
when do dynamic measures of pulse contour tend to predict volume responsiveness
when calculated measurement is > 13-15%
124
why will a hypovolemic patient have a greater degree of SV variation throughout respiratory cycle
as a function of intrathoracic pressure’s effect on RV filling and function
125
things that can cause errors in contour analysis
* SV
* small Vt
* PEEP
* open chest
* RV dysfunction
* dysrhythmias
126
gold standard for assessing myocardial function
TEE
127
where should tip of esophageal doppler probe be
~35 cm from incisors (T5-T6 or at 3rd sternocostal junction)
128
how does esophageal doppler give information about fluid status
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
limitations to esophageal doppler use
aortic stenosis, aortic insufficiency, disease of thoracic aorta, aortic cross-clamping, after CPB, pregnancy
130
esophageal doppler contraindication
Esophageal disease is a relative contraindication
131
what does a wave represent in PAOP waveform
LA systole
132
what does c wave represent in PAOP waveform
mitral valve elevation into LA during LV systole/RV contraction (isovolumetric contraction)
133
what does v wave represent in PAOP waveform
passive LA filling
134
PAOP is an estimate of:
LVEDP
135
events associated with a wave of CVP waveform
* atrial systole
* ventricular diastole
136
Best TEE view for LV ischemia
midpapillary muscle level in shot axis
