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Pressure Monitoring Systems Flashcards

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1
Q

How long is a typical PA catheter?

A

110cm

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2
Q

How large is the balloon on the tip of a PA catheter?

A

1.5cc

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3
Q

Where do the lumens of a PA catheter sit?

A

-PA tip sits in the PA
-two additional lumens at 19cm and 30 cm, sit in the RV, RA or SVC

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4
Q

What is the phlebostatic axis?

A

-located mid axilla under the sternal angle
-make sure the transducer is “zeroed” in relation to atmospheric pr at this height
-transducer needs to be at the level or the RA

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5
Q

If the transducer is placed below the mid chest position the pr will be ______ than the true value.

A

Higher

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6
Q

If the transducer is place above the mid chest position the pr will be _____ than the true value.

A

Lower

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7
Q

If transducer is placed off the mid chest level, how different will the pr reading be?

A

For every 2.5cm off the mid chest level, the displayed pr will be about 2mmHg higher or lower than the actual pr.

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8
Q

Should fluid filled monitoring display the pulse pr?

A

Yes. To test this you can use a square wave (flush) test.

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9
Q

What does overdamping of a waveform do to BP measurement?

A

-underestimation of SBP
-overestimation of DBP

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10
Q

What does underdamping do BP measurement?

A

-overestimated SBP
-underestimated DBP

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11
Q

After flush test, an optimally damped system will have ____ oscillations.

A

2-3

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12
Q

After a flush test, an overdamped system will have ____ oscillations.

A

0

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13
Q

What causes an overdamped system?

A

-system leaks
-blood clots
-air bubbles in tubing or transducer

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14
Q

After a flush test, an underdamped system will have ____ oscillations.

A

greater than 3

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15
Q

What causes an underdamped system?

A

Usually a small air bubble in the system.

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16
Q

Why is hemodynamic monitoring performed?

A

-evaluate intravascular fluid volume
-evaluate cardiac function
-evaluate vascular function
-identify sudden changes in hemodynamic status

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17
Q

What does the dicrotic notch represent on an arterial waveform?

A

Pulmonary and aortic valve closure.

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18
Q

How is volume displacement in the heart seen on an arterial waveform?

A

From the anacrotic notch to the beginning of downstroke. (Ventricular pr exceeds aortic pr and valve opens with ejection of blood).

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19
Q

What does an increased inotropic component of an arterial waveform represent?

A

-increased ventricular contractility
-increased pressure wave reflection from periphery

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20
Q

What does a decreased inotropic component of an arterial waveform indicate?

A

-decreased ventricular contractility
-hypovolemia
-decreased SVR
-these cause upstroke to be longer and a dulled peak

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21
Q

Can true systolic pr be measured?

A

No- monitor chooses tallest component of the waveform.

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22
Q

Why does breathing not normally affect the baseline of an arterial waveform?

A

The monitor scale of 0-300mHg is too large to detect the small variations.

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23
Q

What is pulsus paradoxus?

A

A decrease in SBP and pulse amplitude of greater than 10mmHg during inspiration.

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24
Q

What happens to the arterial waveform as the wave moves towards the periphery?

A

-anacrotic notch and dicrotic notch diminish and disappear
-SBP increases and the waveform narrows while DBP decreases

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25
What happens to BP as we age?
Increases- due to decreased compliance of arteries
26
MAP is the most important indicator of arterial pr measurements. What is normal MAP? At what measurement of MAP is perfusion of vital organs impaired?
Normal= 70-105mmHg -perfusion impaired when MAP <60mmHg
27
Calculation for MAP?
SBP + (DBPx2) / 3
28
What is normal pulse pr (difference b/w SBP and DBP)?
30-40mmHg
29
What is pulse pr reflective of?
SV and arterial compliance.
30
Hypotension is present if SBP is ___, or if MAP is ____.
-<95mmHg -<60mmHg
31
Causes of hypotension include:
-v.dil (decrease in SVR) -hypovolemia -decreased myocardial contractility
32
What changes are seen on an arterial waveform during hypotension?
-loss of inotropic peak; dicrotic notch may disappear -slope and amplitude of anacrotic rise decrease -waveform appears damped
33
Hypertension is present if SBP ___, or if DBP is ___.
->140mmHg ->95mmHg
34
Causes of hypertension include:
-v. cons (increased SVR) -hypervolemia (fluid overload) -increased myocardial contractility (increased catecholamine levels)
35
What changes are seen on an arterial waveform during hypertension?
-each phase is clearly visible and enlarged; reflected waves often visible in descending limb
36
What is the purpose of CVP monitoring?
Approximation of the adequacy of circulating volume and the contractile state of the RV; best indicator of hyper/hypovolemia.
37
What is normal CVP?
8-12mmHg
38
Indications for CVP monitoring:
-major blood loss, dehydration, cardio or non-cardiogenic pulmonary edema -volume resus when peripheral cannulation not possible -TPN and acute hemodialysis -transvenous pacing
39
What are the sites of insertion for CVP?
-subclavian -right internal jugular vein -femoral vein
40
Where should a CVP pr transducer be placed?
Phlebostatic axis (same as for arterial line), but much more important bc the pr reading are small to begin with.
41
Where should the tip of a CVP line be placed?
Proximal SVC
42
What does a CVP measure?
Direct measurement of CVP, RA pr, and RVEDP.
43
On a CXR where should the tip of a CVP line be seen?
Should lie just above the level of the carina.
44
What are the three main wave components of a CVP line and what do they indicate?
- "a" wave: caused by atrial contraction (correlates with p wave) - "c" wave: occurs due to bulging of the tricuspid valve toward atrium during ventricular systole (correlates with QRS) - "v" wave: caused by atrial filling during ventricular systole (a large v wave can indicate tricuspid valve regurge)
45
What factors can make CVP look normal in the presence of hypovolemia?
-systemic v.cons -tricuspid valve dx -decreased RV compliance -therefore; CVP must be interpreted related to HR, BP, and UO
46
How big of a fluid bolus is given during a fluid challenge test for a CVP line?
250-500ml for adults
47
What is the normal response of CVP for a fluid challenge test?
-2-4 mmHg increase in CVP that returns to baseline in 10-15 mins
48
What does it imply if CVP doesn't return to baseline after about 10mins after a fluid challenge test?
Indicates increased circulating volume or decreased RV compliance.
49
What does it imply is the CVP doesn't increase or an increase returns to baseline w/i 5 mins after a fluid challenge test?
Indicates decreased circulating volume (because CVP represents preload).
50
What respiratory factors need to be considered when looking at CVP value?
PPV and PEEP (usually greater than 10cmH2O will start to cause interreference).
51
What does it mean if CVP waveform is not sinusoidal reflective of respiration?
Indicates improper placement of catheter tip.
52
Does CVP increase or decrease with spontaneous inspiration?
Decrease.
53
Does CVP increased or decrease with positive pr inspiration?
Increase.
54
When distinguishing whether increased CVP is due to RV failure or volume overload, what are some signs seen with RV failure?
-weak pulses -tachycardia -dependant edema -decreasing UO
55
When distinguishing whether increased CVP is due to RV failure or volume overload, what are some signs seen with volume overload?
-bounding pulses -increased UO and decreased urine specific gravity -pulmonary edema may be present (ex. CHF pt)
56
What are 3 causes of decreased CVP?
-v. dil (can be due to drugs ex. propofol) -decreased circulating volume -decreased intrathoracic pr
57
How is SVR calculated?
SVR= ((MAP-CVP) / CO) x 80
58
What is the normal range for SVR?
1200-1600 dynes/sec/cm5
59
What is SVRI and how is it calculated?
Intrinsic SVR, accounts for body mass. SVRI= SVR/BSA (normal range is 1600-2400)
60
What the indications for a PA catheter?
No clear group who should automatically receive one. Cardiogenic pulmonary edema, ARDS, and major thoracic sx are possible examples.
61
What does PA catheter allow the measurement of?
-LV preload -pulmonary vascular resistance -CO
62
Contraindications for PA catheter:
-if you won't use the data obtained -right heart mass (tumour/thrombus) -tricuspid or pulmonary valve endocarditis -prosthetic right heart valves (can loop around and cause malfunction) -endocardial pacemakers (can dislodge electrode)
63
What is the purpose of the thermistor located 4cm proximal to to the balloon tip of a PA catheter?
To measure temperature changes for the calculation of CO.
64
According to CRTO, insertions of a PA catheter is...
A delegated procedure.
65
Where is a PA catheter pr transducer placed?
Phleobostatic axis (same as art line, but much more important to be positioned correctly bc a smaller pr is used).
66
Entry of the PA catheter into the pulmonary artery is recognized by a change in _____ pressure.
Diastolic
67
What are normal RV SBP and DBP?
SBP: 15-25mmHg DBP: 1-8mmHg
68
What zone should the tip of the PA catheter sit? Why?
-zone 3 -blood flow is continuous, for accurate measurements
69
At what cm mark is the PA catheter usually in good place at?
50cm
70
What is normal PA SBP and DBP?
SBP: 20-30mmHg DBP: 6-15mmHg
71
Do PA pressures increase or decrease when there is a reduction in blood ejected from RV or a decrease in PVR?
Decrease
72
What causes increased PA pressure?
-PE -decreased PAO2 (pulm v. cons) -increased intrathoracic pr (could be PEEP) -left heart failure or mitral regurge (back pressure)
73
PA catheter is exposed to pr from where in the heart?
LA and LV
74
What is the max balloon inflation time on a PA catheter before infarction occurs?
10-15 seconds
75
Should PAWP be measured during inspiration or expiration? Why?
-end exhalation (least amount of intrathoracic pr when getting reading)
76
Should PAWP be higher or lower than mean PAP?
Lower
77
If PAWP appears higher than mean PAP what does this imply?
-the catheter is not in zone 3 -analytical error -PAWP might be reflecting alv or airway pr
78
Should PAWP be higher or lower than pulmonary artery diastolic pr? Why?
Lower (bc the higher pr in the pulmonary artery is needed to push the blood into the LA).
79
How do high alv pressures cause PAWP reading to be inaccurate?
Decreased venous return caused by increased intrathoracic pr will cause inaccurate readings.
80
What is normal pulmonary artery diastolic pr?
6-15mmHg
81
What is normal PAWP?
4-12mmHg
82
How do you calculate left ventricular preload?
PVR = ((Mean PAP-PAWP) x 80) / CO
83
What is the normal range for PVR (left ventricular preload?
120-140 dynes/sec/cm5
84
How do you calculate intrinsic PVR?
PVRI= PVR/BSA
85
What is the normal range for PVRI?
200-400 dynes/sec/cm5
86
Which port should a mixed venous sample be taken from a PA catheter? How fast should the sample be taken?
Distal port- to allow for best mixing of blood. Sample should be aspirated slowly (1ml per 20 sec) to prevent contamination with oxygenated blood. You also don't want to cause back pr in the heart.
87
What is normal SV?
60-130ml/beat
88
What is normal CO?
4-8L/min
89
What is the gold standard for measuring CO?
Thermodilution cardiac output technique.
90
What solution is used for CO thermodilution technique?
D5W
91
How does the thermodilution technique work to measure CO?
-baseline body temp and D5W temp are established -cold solution is injected into the proximal port and temp is recorded at thermistor -temp-time curve is created -CO is inversely proportional to the area under the curve (more temp change= lower CO)
92
When looking at CO temp-time curves what does a low CO state look like vs. a high CO state?
Low CO: Higher and longer curve to get to the top High CO: Shorter and smaller curve
93
What used to be the gold standard for measuring CO?
Fick CO- involved analyzing inhaled and exhaled gases and determining C(a-v)O2
94
What are some other methods of analyzing CO?
-continuous CO monitoring (not done often anymore) -continuous SvO2 monitoring -transtracheal, transesophageal (esophageal balloon), and intravascular U/S -doppler U/S (non-invasive) -thoracic bioimpedance (non-invasive)
95
What are some complications of PA catheter insertion?
-arterial puncture -pneumothorax -arrhythmias (most common complication- PVCs or non sustained v tach) -infection is fairly common -pulmonary infarction (not common) -PA rupture (not common)

Cardiopulmonary (4 decks)

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