Hemodynamic Monitors And Equipment Flashcards
What is the first sound measured in a manual BP?
SBP
What is the last sound that disappears in a manual BP?
DBP
What method do automatic BP machines use to measure BP?
Oscillometric
What is the most accurate data provided by the oscillometric method of BP measurement?
MAP
What is the ideal length of the bladder in a BP cuff?
80% of the extremity circumference
What is the ideal width of the bladder for BP measurement?
40% of the extremity circumference
A cuff that is too small what?
Overestimates the BP. The cuff pressure required to occlude the artery is HIGHER with a cuff that is too small.
A cuff that is too large?
Underestimates the SBP. The cuff pressure required to occlude the artery is lower with a cuff that’s too large.
What are some causes of an over-dampened arterial line?
(Underestimated SBP and overestimated FBP)
Common causes are air bubbles, clot at the end of the catheter tip, and low flush bag pressure.
What does it mean for your arterial line to be optimally dampened?
Baseline is established after 1 second (of square test-flush)
What does it mean for your arterial line to be under-dampened?
Baseline is established after several oscillations (SBP is overestimated, DBP is underestimated) ~ MAP is accurate
Causes: stiff tubing; catheter whip
What does it mean for your arterial line to be over-dampened?
Baseline is re-established with NO oscillations.
SBP is underestimated; DBP is overestimated. ~ MAP is accurate
Causes: air bubble, clot in tubing, low flow flush bag, kinks, or loose tubing.
How far is the insertion site from the subclavian to the vena cava/Rt atrial junction?
10 cm
How far is the insertion site from the Rt IJ to the vena cava/rt atrial junction?
15 cm
How far is the insertion site from the left IJ to the vena Cava / rt atrial junction?
20 cm
How far is the insertion site from the femoral to vena cava / rt atrial junction?
40 cm
What is the distance from the vena cava / rt atrial junction to the Catheter tip in the rt atrium?
10 cm
How far is the distance from the vena cava to the art ventricle?
15 cm
How far is the distance from the vena cava to the Pulmonary artery?
15-30 cm
How far is the distance from the vena cava to the PAOP location?
35
What is the added risk of accessing from the Lt IJ for central line?
Puncturing the thoracic duct. (This can cause chylothorax)
When should you NOT float a PA cath?
If the patient has a current LBBB ~ if the PA catheter causes a RBBB ~ complete heart block could ensue.
What is the classic presentation of pulmonary artery rupture?
Hemoptysis
What are the 3 peaks in a CVP waveform?
a, c, and v
What does the a wave correlate with?
Atrial contraction
**just after atrial depolarization
What does the c wave correlate to?
Tricuspid valve elevation into the right atrium ~ RV pressure causes the valve to bulge (isovolumetric contraction)
**just after QRS complex (ventricular depolarization)
What does the v wave correlate to?
Atrium passive filling
**just after T wave begins (ventricular repolarization)
What are the two troughs of the CVP waveform?
x and y
What does the x part of the CVP waveform mean?
Downward movement is contracting RV
**ST segment
What does the y portion of the CVP waveform mean?
Atrium passively empties in the RV
**after T wave ends
Where should the CVP be zeroed?
Phlebostatic axis
Where is the phlebostatic axis?
Fourth intercostal space mid anteroposterior level
When should the CVP be measured?
End expiration
What are some factors that increase CVP?
Hypervolemia
RV failure
Tricuspid stenos
PEEP
VSD
Pulmonic stenosis
Cardiac tamponade
Constrictive pericarditis
What are some factors that decrease CVP?
Hypovolemia (hemorrhage)
What is the normal CVP?
0-10
In what conditions would you have a loss of the a wave in the CVP waveform?
Afib
V-pacing
In what conditions would you have a large/increased a wave in the CVP waveform?
Anytime the atrium has to contract against a high resistance
Tricuspid stenosis
Diastolic dysfunction
Myocardial ischemia
Rv hypertrophy
PVCs
AV dissociation
In what conditions would you have an increased/large v wave in the CVP waveform?
Tricuspid regurge
Acute increase in intravascular volume
RV papillary muscle ischemia
What are some traits of the PA waveform in the RV
Systolic pressure increased; diastolic pressure = CVP (valve is open)
How does the PA waveform change in the Pulmonary artery?
Diastolic pressure increases
Dicrotic notch appears
how does the PA waveform change when is enters occlusion (PAOP) wedged?
This waveform is basically the CVP for the left side. The values mean the same (just on the left side)
Where should the tip of the PA cath be placed?
Zone 3
In this zone, there is a continuous column of blood between the tip of the PAC and the left ventricle ~ provides the most accurate LVEDP
What are some conditions that here PAOP overestimates LVEDP?
Impaired LV compliance
Mitral valve disease
Left to right cardiac shunt
Tachycardia
PPV
PEEP
COPD
pHTN
What are some conditions that would cause the PA cath to underestimate LVEDV?
Aortic valve insufficiency
(In thermodilution) If CO is high and the injectate rapidly travels towards the distal tip of the PA cath, the area under the curve (AUC) is what?
Smaller
Area is inversely proportional to cardiac output.
Better CO = small AUC
(In thermodilution) If CO is low and the injectate slowly travels towards the distal tip of the PA cath, the area under the curve (AUC) is what?
Larger
Area is inversely proportional to cardiac output.
Worse CO = larger area under the curve
What are some conditions that may underestimate your CO when using thermodilution?
Injectate volume is too high
Injectate volume is too cold
What are some conditions that overestimate CO when using thermodilution?
Injectate volume is too low
Injectate solution too hot
Partially wedged PAC
Thrombus in tip of PAC
What are two conditions that make it difficult to predict CO when using thermodilution?
Intracardiac shunt
Tricuspid regurgitation
What is the equation for a mixed venous (and/or) SvO2?
SaO2 - VO2 / Q (CO) x 1.34 x Hgb x 10
What is a normal SvO2?
65-75%
When does SvO2 decrease?
Oxygen consumption increases or oxygen delivery decreases
What are some conditions that will increase O2 consumption? ~ resulting in a decreased SvO2
Stress
Pain
Thyroid storm
Fever
What are some conditions that result in a decreased O2 delivery? Thus decreasing SvO2?
Decreased PaO2
Decreased Hgb
Decreased CO
What are some conditions that decrease O2 consumption, ~ thus resulting in an increased SvO2?
Hypothermia
Cyanide Toxicity
What are some conditions that result in an increased O2 delivery ~ thus resulting in an increased SvO2?
Increased PaO2
Increased Hgb
Increased CO
Why does sepsis cause an increased SvO2?
Even though sepsis creates a high cardiac output, oxygen bypasses tissues restyling in end-organ hypoxia
Preload responsiveness is expected to be present if a 200-250 mL bolus increases stroke volume in excess of what?
10%
(Pulse pressure variation)
During inspiration, what happens to RV pressure, LV pressure, and stroke volume?
A positive breath augments LV filling ~ compression of the pulmonary veins and pleural restriction impedes RV filling.
Increased LV filling increases stroke volume
(Pulse pressure variation)
During expiration, what happens to RV filling and LV filling, and stroke volume?
LV filling decreases (decreased RV preload on previous beat reduces LV preload)
Decreased LV filling results in reduced stroke volume
What are 6 situations where pulse contour analysis won’t provide reliable data?
Spontaneous breathing
PEEP
Small tidal volumes
Open chest
RV failure
Dysrhythmias
Where should the esophageal Doppler be placed?
The tip should be placed 35 cm from the incisors or T5/T6
(Esophageal Doppler)
What is peak velocity?
Index of contractility
(Esophageal Doppler)
What is flow time?
Timing of flow from the left ventricle during systole
(Esophageal Doppler)
What is mean acceleration?
The average speed on the upstroke of the waveform
(Esophageal Doppler)
What is cycle time?
The time of one cardiac cycle
(Esophageal Doppler)
What is stroke distance?
How far SV is pumped along the aorta per beat
(Area under the curve)
What is a relative contraindication to the esophageal Doppler?
Esophageal disease l
What are some limitations to the esophageal Doppler?
Aortic stenosis
Aortic regurgitation
Dx of thoracic aorta
Aortic cross-clamping
After CPB
Pregnancy
What is the conduction velocities in the SA and AV nodes?
.02-.10 m/sec (slow conduction)
What is the conduction velocities for myocardial muscle cells?
0.3 - 1 m/sec (intermediate conduction)
What is the conduction velocities for the bundle of his, bundle branches, and purkinje fibers?
1-4 m/sec (fast conduction)
Which accessory pathway connect the atrium to the AV node?
James fiber
Which accessory pathway connects the atrium to His bundle?
Atrio-hisian fiber
Which accessory pathway connects the atrium to the ventricle?
Kent’s bundle
What accessory pathway connects the AV node to the ventricle?
Mahlon bundle
In the ventricular action potential, what does phase 0 correlate with on the EKG?
Rapid depolarization (QRS)
** Na+ in
In the ventricular action potential, what does phase 1 correlate with on the EKG?
Initial repolarization (QRS)
**Cl- in, K+ out
In the ventricular action potential, what does phase 2 correlate with on the EKG?
Plateau phase (QT interval)
**Ca in, K+ out
In the ventricular action potential, what does phase 3 correlate with on the EKG?
Final repolarization (T wave)
**K+ out
In the ventricular action potential, what does phase 4 correlate with on the EKG?
Resting phase (T—> QRS)
**K+ leak
What is the electrical event of the atria during by the P wave?
Depolarization begins
What is the electrical activity of the atria during the PR interval?
Depolarization complete
What is the electrical activity of the atria AND ventricle during the QRS?
Atria: repolarization
Ventricles: depolarization begins
What is the electrical activity of the ventricle during the ST segment?
Depolarization complete
What is the electrical activity of the ventricle during the T wave?
Repolarization begins
What is the electrical activity of the ventricle after the T wave?
Repolarization complete
What is the J point?
Where the QRS complex ends and the ST segment begins
(By measuring this point relative to the PR segment, we can quantify the amount of ST elevation or depression)
As a rule, what elevation/depression of the J point is deemed significant?
+ 1 or - 1
How does too low of potassium affect the EKG?
U wave
ST depression
Flat T wave
Long QT interval
How does too high of potassium affect the EKG?
(In order of appearance ~ early to late)
Narrow and peaked T waves
Short QT
Wide QRS
Low P amplitude
Wide PR
Nodal block
Sine wave fusion of QRS and T ~ VF
How does hypercalemia affect the EKG?
Short QT
How does hypocalcemia affect the EKG?
Long QT
How does hypermagnesia affect the EKG?
No effect unless very very high
Heart block
Cardiac arrest
How does hypomagnesia affect the EKG?
No significant effect unless very low ~~
Long QT
When does a positive deflection occur?
When the vector of depolarization travels towards the positive electrode
When does a negative deflection occur?
Vector of depolarization travels away from the positive electrode
When does a biphasic deflection occur?
When the vector of depolarization travels perpendicular to the positive electrode
When the heart depolarizes, the direction of the vector goes from?
Base to apex
Endocardium to epicardium
When the heart repolarizes, the direction of the vector goes from?
Apex to base
Epicardium to endocardium
