Exam 3 Flashcards
1
Q
Factors that increase CVP
A
Hypervolemia (volume overload/perfusionist overfilling) Forced Exhalation Tension pneumo Heart failure Pleural effusion Decreased cardiac output cardiac tampenade Mechanical ventilation and the application of PEEP
2
Q
Factors the decrease CVP
A
Hypovolemia (perfusionist underfilling)
Hypovolemia
Deep inhalation
shock
3
Q
Six Factors Affecting Venous Return
A
- Musculovenous pump
- Decreased venous capacitance
- Respiratory pump
- Vena Cava Compression
- Gravity
- Pumping Action of the Heart
4
Q
Musculovenous pump
A
Contraction of limb muscles during normal locomotion (walking, running, swimming) promotes venous return by the muscle pump mechanism (n/a on CPB)
5
Q
Decreased venous capacitance
A
Sympathetic activation of veins decrease venous compliance, increase venous tone, increase CVP and venous return which increases blood flow through the circulatory system
6
Q
Respiratory pump
A
during inspiration, the intrathoracic pressure is negative and abdominal pressure is positive
7
Q
Vena Cava Compression
A
an increase in the resistance of the vena cava, when the thoracic vena cava becomes compressed decreases venous return
8
Q
Gravity
A
the effects of gravity on venous return seem paradoxical, when a preson stands up hydrostatic forces cause the RAP to decrease and the venous pressure in the limbs to increase. This increases the pressure gradient for venous return from the dependent limbs to the right atrium; however, venous return decreases
9
Q
Why do the effects of gravity cause venous return to DECREASE?
A
CO and arterial pressure decrease when standing (because RA pressure falls)
Flow decreases; arterial P falls more than RAP. Pressure gradient driving flow through the entire circulatory system is decreased.
(Orthostatic hypotension)
10
Q
Pumping action of the heart
A
Atrial pressure changes alter CVP during cardiac cycle. CVP is altered because there is no valve between the heart’s atria nad veins. Atrial pressure changes venous pressure and therefore alters venous return
No valve; can assume pressures are equal
11
Q
Subclavian vein & internal jugular vein insertion catheter length
A
20 cm
12
Q
Femoral venous access catheter length
A
60cm
13
Q
CVP Insertion Sites
A
Subclavian internal jugular external jugular femoral antecubital
14
Q
Seldinger Technique
A
Catheter over guidewire
15
Q
Do peds use swan ganz catheters?
A
No, they don’t make them small enough
16
Q
Central Line Complications
A
Cardiac Tampenade Wire or catheter embolism Vascular injuries (non PA) -Hemothorax -Hydrothorax -Carotid artery injury -subclavian a. aneurysm Pulmonary artery rupture Pneumothorax Air Embolism Fluid extravasation
17
Q
A Wave
A
Increased Atrial Pressure during right atrial contraction. Correlates with P wave on EKG
18
Q
C Wave
A
Slight elevation of the tricuspid valve into the right atrium during early ventricular contraction. Correlates with QRS
Due to isovolumic RV contraction; closes tricuspid valve and causes it to bow back into RA
“tricuspid valve close and ventricular contraction”
19
Q
X Wave
A
Downward movement of ventricle during systolic contraction. Before T wave on EKG.
Midsystolic Event
“Systolic collapse in atrial pressure”
20
Q
V Wave
A
Pressure produced when blood filling the right atrium comes up against a closed tricuspid valve. Occurs as the T wave is ending on an EKG
Last atrial pressure increase caused by filling of the atrium with blood from the vena cava; late systole with tricuspid still closed
“venous filling of the atrium”
21
Q
Y Wave
A
Tricuspid valve opening the diastole with blood flowing into the RV. Occurs before P wave on EKG
“Diastolic collapse in atrial pressure”
Decrease in atrial pressure as tricuspid open and blood flows from atrial to ventricle
22
Q
What determines change in CVP?
A
CVP = V/ Compliance
23
Q
What part of CVP waveform coincides with point of maximal filling of the right ventricle?
A
Peak of “a” wave
24
Q
What part of CVP waveform should be used for measurement of RVEDP?
A
Peak of “a” wave
Should be measure at end-expiration; machines just “average” the measurement
25
Systolic Events of CVP waveform (ventricular events)
cxv
26
Diastolic events of CVP waveform (ventricular events)
ay
27
Tachycardia and CVP
Short PR interval can cause "a" and "c" waves to fuse
Reduces time spent in diastole causing short "y" descent
"V" and "A" may appear to merge
28
Bradycardia and CVP
Each wave becomes more distinct
"H" wave may become evident- plateau wave in mid or late diastole
"H" wave has little clinical significance
29
A Fib and CVP
"A" wave disappears (no atrial contraction)
"C" wave more prominent (atrial volume is higher at the beginning of systole because the atrium did not empty)
30
PVCs and CVP
Large a wave
| a wave at expected time (not premature)
31
Tricuspid Regurgitation and CVP
RA gains volume during systole so "c" and "v" wave is much higher
RA sees RV pressure curve becomes "ventricularized"
32
Tricuspid Stenosis and CVP
Problem with atrial emptying and a barrier to ventricular filling on the right side of the heart
Mean CVP elevated
"a" wave usually prominent as it tries to overcome the barrier to emptying
"Y" descent muted as a result of decreased outflow from atrium to ventricle
33
Pericardial Constriction and CVP
Limited venous return to heart, elevated CVP, end diastolic pressure, equalization in all cardiac chambers
Prominent "a" and "v" waves; steep "x" and "y" descnets
Characteristic M or W pattern, dip and plateau (square root sign)
34
Cardiac Tampenade and CVP
Changes in atrial and ventricular volumes are coupled so total cardiac volume doesnt change
CVP monophasic with single, prominent "x" descent and a muted "y" descent
Similar to pericardial constriction but not exactly the same
35
CVP and Respiration
Increases during Expiration
| Decreases during inspiration
36
What is CVP when on bypass?
0
If not zero, you're not emptying; get better venous return!!
37
As you restrict your venous line, what is the relationship between arterial flow and venous return?
Arterial Flow > Venous Return
This will fill your heart. CVP rises (preloads RV); Pa Volume rises (preload LV) arterial P rises
Therefore, perfusionists control preload!!
38
Who invented the Swan Ganz catheter and in what year?
Dr. Jeremy Swan & Dr. William Ganz
Cedars-Sinai Medical Center
Invented in 1970
Fabricated by Edwards Laboratories
39
Indications for PAP Monitoring
- Management of cardiopulmonary pressures and flows
- Assess CV Function
- Perioperative monitoring in surgical pts
- Shock
- Assess pulmonary status
- Assess fluid requirements
- Assess obstetric pts
- Therapeutic & diagnostic indications
40
Indications for Swan-Ganz PA Catheter
Assessment of respiratory distress
Assessment of Shock
Assessment of Therapy
Assessment of fluid requirement in critically ill patients
Assessment postoperative in heart surgery pts
Assessment of valvular disease
Assess cardiac tamponade/constriction
41
What is the #1 use for a swan?
assess fluid requirement in critically ill patients
42
What types of things are we looking at when assessing therapy?
Afterload reduction
Vasopressors
Beta Blockers
Intra-aortic balloon counter-pulsation
43
What do we look at when we assess fluid requirement in critically ill patients?
Hemorrhage
Sepsis
ARF aka Acute kidney injury
Burns
44
What can a Swan-Ganz Catheter do and measure?
```
Preload
Afterload
SVR
PVR
Cardiac Output (thermal dilution)
Cardiac Index
Venous Sat (Oximetric Swan)
Pacemaker (paceport swan)
```
45
Preload
Reflected by end-diastolic pressures of ventricles, as generate by volume of blood into ventricles just before next contraction
46
What measures RV preload?
CVP measures right filling pressures
47
What measures LV preload?
PAWP measures left ventricular filling pressures
48
Afterload
pressure the ventricles must pump against to eject blood; resistance to ventricular systole
49
What are the determinants of CO?
```
Preload
Afterload
Contractility
Heart Rate
Heart Rhythm
```
50
Where is the thermistor located?
About 3cm behind the tip
51
Two ways to measure CO (thermal dilution)
10ccs of cold saline under 10C or room temp injected through RA. Drop in blood temp recorded as cooler fluid passes the tip of the thermistor
Incorporation of heating coil on catheter 30cm from tip, residing in atrium area, eliminates the cold fluid bolus
52
Cardiac Index
Measurement considered more accurate than CO, individualized to heigh and weight of pt
53
What type of swan used for venous saturation?
Oximetric Swan
54
Venous Saturation Measurement
Catheter with fiber-optic based probe extended and lodged into ventricle wall provide instant readings of SvO2 or oxygen saturation of ventricle tissues. Finite life as sensor becomes coated with protein and it can irritate ventricle via the contact area
55
What type of swan used for pacemaker?
Paceport Swan
56
PAOP
Pulmonary artery occlusion pressure (PAWP)
57
PADP
pulmonary artery diastolic pressure
58
What does PCWP tell us?
Indirect measure of LAP (become of large compliance of pulmonary circulation)
Cause of acute pulmonary edema (PCWP >20mmHg)
Diagnosis severity of LV failure and mitral stenosis
Diagnosis of ARDS
59
What is PCWP the gold standard for determining?
Cause of acute pulmonary edema
60
What PCWP indicates acute pulmonary edema?
>20mmHg
61
What is ejection fraction related to?
LVEDP
62
Potential Problems Getting Accurate Hemodynamic Data
```
Body position relative to transducer
Conncetion of transducer to wrong catheter port
Cardiac dysfunction
Catheter Whip
Ventilatory Effects
```
63
Catheter Whip
Hyperdynamic Heart
| Excessive catheter length
64
What are some problems with cardiac dysfunction that create problems getting accurate data?
```
Mitral Regurgitation (PCWP elevated due to elevated v wave)
LV dysfunction- (PCWP elevated due to amplified a wave)
Tachycardia (not enough time for PCWP and LVEDP to equilibrate)
```
65
Complications of Pulmonary Artery Catheterization
```
Cardiac arrhythmias
Bundle Branch Block
Balloon Rupture
Catheter Knotting
Infection
Thrombus formation
Pneumothorax
Pulmonary Ischemia or infarction
Damage to or rupture of PA segment
Cardiac perforation & tamponade
```
66
Why Wide range of results in benefits of swan?
- Knowledge of basic principles varies
- Hemodynamic end-points of tx varies
- Distance of catheter tip from LV varies
- Delay in decision to use a PA catheter
- Patients very ill, one piece of puzzle only
67
Surgical Cutdown Insertion Technique
Direct needle-puncture of vessel or tiny incision
68
Percutaneous Insertion Technique
More common
Introducer to access the vessel
Guide wire; wire removed; catheter introduced through insertion sheath
69
What affects stroke volume?
Preload
Afterload
Contractility
70
What variables affect cardiac output?
Metabolic rate and oxygen demand
Gender
Age
Body Size
71
What is the most potent determinant of CO?
Metabolic rate and oxygen demand
72
Critially ill/injured patients usually need a CO that is _____% higher than normal.
50%
73
Co normally is ______% less in a female than a male with equivalent BSA.
10 %
74
Neonatal Demand Range
150-200 cc/kg
75
Normal BSA Range
1.8 l/m/m^2 to 2/4 l/m/m^2
76
Normal CPB Flow- Kg
50-75 cc/kg/min
77
____% to _____% of people have PFO's
20-30%
78
Anatomic Shunt
Volume and circulatory flow changes that create differences in saturation, pressure, and flow in the chambers
79
L to R Shunting
Overloads R ventricle, PBF>SBF. Seen in ASD, VSD, PFO, and acyanotic congenital abnormalities.
80
R to L Shunting
PBF < SBF, TOF and cyanotic congenital defects (skips the heart)
81
Invasive Ways of Measuring CO
Fick oxygen consumption method
Indicator- dilution method
Thermodilution method
82
Fick Principle: Minute volume may be calculated if...
1. Tracer substance amt entering or leaving an organ are unknown
2. Tracer concentration entering and leaving an organ are known (ex. the lungs)
83
Fick Principle Equation
CO= Oxygen Consumption (cc/min)/ A-VO2 Content difference (cc/dL blood)
84
Fick Method Simultaneously Measures....
Arterial oxygen content
Mixed venous oxygen content
Oxygen uptake by lungs
85
How to measure oxygen uptake by lungs?
1. Assume 3.5 ml/kg/min (avg adult)
2. Analyze o2 content different of inspired minus expired air collected over 3 minute period
3. use breath-by-breath metabolic monitor
86
Fick Technique Advantages
Low CO
| Better than thermodilution for regurgitant tricuspid or pulmonary valves
87
Fick Technique Disadvantages
```
Steady hemodynamic & metabolic state- 3 min
Requires multiple people
Time consuming
Requires meticulous technique
Not easily repeatable/ not continuout
Results not readily available for immediate clinical intervention
Not valid in presence of shunts
Not accurate for high cardiac outputs
```
88
What does indicator dye measure?
Flow! (Not velocity)
89
Indicated Dye Characteristics
```
Mixes well with blood
Easy to determine concentration
Stable
Not retained by the body
Not toxic
```
90
Indicator Dye Examples
Radio-iodated serum albumin
Indocyanine dye (cardiogreen)
O2
Temperature (iced or room temp saline or 5% dextrose)
91
Dye Dilution Principle
PA Injection of dye
Continuous sample drawn in systemic artery
Plot concentrations graphically
92
Does an open system have recirculation?
No recirculation
93
Does a closed system have recirculation?
Yes, has recirculation
94
What is QP/QS normally?
1
95
What is QP relate to in QP/QS
Right heart
96
What is QS relate to in QP/QS
Left heart
97
If QP/QS is greater than one, which side output is greater?
RV output greater than LV output
98
If QP/QS is less than one, which side output is greater?
LV output greater than RV output
99
Dye dilution Advantages
Most accurate with high-cardiac output
| Overall accuracy plus/minus 5%
100
Dye Dilution Disadvantages
```
Not valid with shunts, regurg, shock
Dye unstable/photosensitive
Risk of allergic rxn to dye
Calibration using sample of pts blood
Careful metered blood withdrawal
Not repeatable or have continuout measurement
Patient must be stable metabolic state for 40 sec
Time consuming
Not accurate with low output
```
101
Thermodilution Modified Equation
CO = (60)(1.08)(C)(V) (T-Ti)/ int Tb*dt
102
Thermodilution Technique
```
Patient supine (less than 20 degrees)
Injectate volume (10, 5, or 3 ml)
Injectate temp (room or iced)
Set stopcocks, computers
4 second injection or less
Repeat 3x, 90 seconds apart
should have 3 values within 10% of each other
```
103
What type of cardiac output does thermodilution work with
High cardiac output
104
Patient generated errors with thermodilution method?
Low CO
Arrythmias
Flow abnormalities (regurg)
105
Technique generated errors with thermodilution method?
```
Wrong injectate, temp, volume
Injection too slow
THrombus or plasma protein on catheter
Thermister defect
INcorrect computation factor entered
```
106
Thermodilution Method Advantages?
No blood withdrawal
Easy and quickly performed
Continuous info can be available (venous pulmonary artery catheter)
Results readily available
107
What method has continuous information available?
Thermodilution via venous pulmonary artery catheter
108
Thermodilution method disadvantages
Not accurate in presence of tricuspid regurg and shunts
| Least accurate if CO is low
109
Non-Invasive Ways of Measuring CO
Doppler Ultrasonography & Echo
Thoracic electrical bioimpedence
Electromagnetic Flow Probes
110
What is are the normal frequencies in dianostic ultrasound?
2 and 18 MHz
111
Two approaches to ultrasonic BF
Transit time
| Doppler Principle
112
Doppler Ultrasonography is used to assess...
Insufficient valves
LV function
EF
113
Systole: Thoracic blood volume _________ and impedence _________
increases; decreases
114
Diastole: Thoracic blood volume _______ and impedence _________
decreases; increases
115
TEB Routinely Displayed Parameters
```
HR
BP
MAP
Thoracic fluid content
CO/ CI
Acceleration index
Velocity index
Systolic Time ratio
SVR/SVI
LV ejection time
```
116
Acceleration Index
how fast the ventricular volume change occurs
117
Velocity index
maximum speed of blood flow
118
TEB Advantages
```
Continuous Real-time data
Noninvasive
Rapid computer processing
no extensive training required
cost effective
not affected by mitral or pulmonic regurg
```
119
TEB Disadvantages
Accuracy affected by LBBB, L to R intra cardiac shunts, aortic regurg, sepsis
Uncontrolled muscle movement and patients inability to cooperate creates artifact
120
Principle of magnetic induction
move electrical conductor through magnetic field get induced voltage proportional to velocity of motion
121
What does electromagnetic flow probe measure?
Mean velocity of flow
| Calculates flow
