hemodynamic montoring Flashcards
- what is the gold standard of BP monitoring?
2. what are the pros of this monitoring?
- arterial blood pressure
2. continuous “beat to beat” monitorning, immediate assessment of treatment efficacy, and access for blood sampling
- identify characteristics of arterial pulse pressure waveform as it is transmitted
- what is pulse pressure? what can high or low PP indicate?
- describe the components of the arterial waveform and what they indicate
- describe aPPV. Why do we use it in the OR?
- regcognize the components of a CVP/RAP waveform and their corresponding medical events (a,c,v waves and x and y descents).
- dexcribe the impact of ventilation on pressures (particularly wedge) in a spontaneously breating and mechanically breathing patient
- Identify positioning for the PA catheter in centimeters for a PAOP reading. What physiologic location does this correspond to?
- In broad terms, recognize the factors that might alter the relationships among central cardiovascular pressures and volumes. (see top of page 7 in your notes and pg 319)
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indications for arterial line:
name 9 indications:
- large or rapid swings in BP are predicted
- when BP must be kept within narrow parameters
- controlled hypotension
- aortic cross clamping
- cardiopulmonary bypass
- when non invasive BP is unreliable or impossible
- when repeat blood gas or labs are needed
- respiratory failure
- trauma (burns, shock).
A. indications of arterial line: what patient populations:
large swings in blood pressure or when tight BP parameters needed:
A. large swings in blood pressure or when tight BP parameters needed:
- CAD, valve disease, carotid disese
- impaired intracerebral autoregulation
- intracerebral or aortic aneurysm
what CV surgical actions will warrant an arterial line
- cross clamping of aorta
2. cardiopulmonary bypass
what factors make noninvasive pressure measurement is unreliable or impossible:
- positioning
2. morbid obesity
what needs (along with any of the other indications) warrant an art line?
need for frequent labs or abgs
what respiratory needs warrant an art line?
- weaning from vent
- metabolic and acid base abnormalities
what acute issues warrant an art line (think ER etc.)?
burns, shock, trauma
what does arterial blood pressure (waveform/monitor) show?
- volume status
- contractility
- SVR
- HR
what is the phlebostatic axis?
the standard reference point to calibrate a transducer to atmospheric pressure (4th intercostal space/ midaxillary line)
what 5 factors determine peak Systolic Blood Pressure?
- Volume and velocity of left ventricular ejection
- Peripheral arteriolar resistance
- Dispensability (flexibility) of the arterial wall
- Viscosity of the blood
- End-diastolic volume in the arterial system
what 4 factors influence diastolic blood pressure:
- Blood viscosity
- Arterial dispensability (how much does it factor)
- Peripheral resistance to flow
- Length of the cardiac cycle
what is pulse pressure
the difference between the systolic and diastolic pressure
- define a narrow blood pressure
2. what is a normal pulse pressure? therefore wide and narrow are…
- an increase in the diastolic blood pressure or a decrease in the systolic blood pressure causes a small difference between the two numbers.
- normal pulse pressure=40 mmHg; high is >40; low is <40.
- what are general causes of widened pulse pressure?
2. what are specific causes?
- issues that increase increase systolic or decrease diastolic
- systemic HTN
- atherosclerosis (may increase systolic d/t tight vessels)
- aortic insufficiency/ regurg (higher systolic volumes d/t regurgitated blood)
- aortic dissection
- hyperthyroid (increases metabolism=increased bp)
- anemia (
- what are the general causes of narrowed pulse pressure?
2. what are the specific causes?
- decreased systolic or increased systolic
- cardiac tamponade (pressure on heart causes decreased filling which decreases systolic; diastolic is higher d/t increased pressure during rest).
- hypovolemia (less volume causes lower systolic pressure)
- CHF (higher diastolic pressures d/t full heart, lower ejection d/t stretched heart=lower systolic)
- cardiogenic shock (less pump strength=low systolic)
- aortic stenosis(causes decreased systolic d/t low ejection volume)
what are the 3 componets of arterial pressure waveforms:
- anacrotic limb
- dicrotic limb
- dicrotic notch
- what is the anacrotic limb?
- what wave of ECG does it correspond with?
- what does it reflect? and as far as blood flow?
- what is it the “peak” of?
- the initial upsweep of the arterial waveform
- corresponds with QRS complex
- Reflects contractility (i.e reflects velocity of blood ejected from left ventricle through the aortic valve)
- Peak is systolic BP
the anacrotic limb Reflects contractility (i.e reflects velocity of blood ejected from left ventricle through the aortic valve)
- what does a steep upstroke mean?
- what does a slow upstroke mean?
- -• A steep upstroke = strong LV function.
- -• (Upstroke more vertical in patients with regurgitation, anemia, fever and hyperthyroidism
- -• Slower upstroke in aortic stenosis or ventricular failure)
Dicrotic Limb (2) A. what part of the waveform is this? 1. what does it reflect? what does it reflect in the blood pressure? 2. what does a steep downstroke with a low dicrotic notch indicate? 3. where does it begin and end?
A. Dicrotic Limb (2) – the downstroke
1• Reflects decreasing SVR (decreased BP and blood flow to the periphery)
2• A steep downstroke with a low dicrotic notch indicates a low SVR and a rapid diastolic runoff
3• Begins at end of anacrotic limb and goes back to baseline.
A. Dicrotic Notch (3) also known as…?
- what does it reflect?
- what type of cardiac condition will cause a less distinct dicrotic notch?
- when does the dicrotic notch occur?
- how does the position of the dicrotic notch relate to SVR?
o Dicrotic Notch (3) – the groove
1• Reflects aortic valve closure with onset of diastole
2• will not see a distinct dicrotic notch with aortic valve regurg/insufficiency
3• Occurs at end of T wave
4. The lowerv the notch is on the dicrotic limb, the lower the SVR
dicrotic notch: what happens pressure wise to cause it?
-when the LV pressure decreases to less than aortic root press and the aortic valve snaps shut. A tiny upstroke occurs on the waveform due to the P increase as blood pushes back against a closed valve.
How does the position of the dicrotic notch relate to SVR?
• The position of the dicrotic notch correlates with the SVR
- -a notch that is high on the downslope suggests a high SVR
- -a low SVR will have a notch that’s lower
• Pulse Pressure Transmission to periphery
1. how does pulse pressure increase as it is propelled from the heart to the periphery?
• Pulse Pressure Transmission to periphery
- Pulse pressure increases as it is propelled centrally →peripherally
- Affected by stroke volume and compliance of arteriole tree
Large Arterial Branches=7-10 m/sec
Small Arteries=15-35 m/sec
(The dorsal is pedis pulse reflects the highest SBP in the body).
- how does the Velocity of Transmission change
- Normal Aorta=
- Large Arterial Branches=
- Small Arteries=
1• Velocity of Transmission:
• As the arterial pulse leaves the heart, pulse pressure increases (i.e. a more pronounced anacrotic limb) due to the decreasing arterial lumen size and the reflection of the BP wave also increases as it moves toward the periphery:
2. Normal Aorta=3-5 m/sec
3. Large Arterial Branches=7-10 m/sec
4. Small Arteries=15-35 m/sec
(The dorsal is pedis pulse reflects the highest SBP in the body).
what conditions cause abnormal arterial waveforms?
Abnormal Arterial Pressure Waveforms – occurs with various cardiac diseases or issues (ex. Aortic regurg, stenosis, patent ductus arteriosus).
Arterial Pulse Pressure Variation and Volume Monitoring
• Volume status can be measured by: 9 things-
Arterial Pulse Pressure Variation and Volume Monitoring
• Volume status can be measured by
1- HR – a late symptom of ↓volume (15-30% ↓volume before tachycardia)
2- BP- a large disparity between arterial and NIBP. Also a late s/s
3- CVP – an inaccurate predictor Affected by ventilation, position. “Trends” are followed
4- UO –poor accuracy
5- TEE
6- Shock Index = HR/SBP
(a SI >0.7 = hypovolemia shown to be very sensitive to early acute hypovolemia than HR or BP alone)
7- Transesophogeal Doppler – invasive, expensive, requires significant training
8- Tracer Dye Analysis- invasive, expensive
9- Arterial Pulse Pressure Variation- invasive but not so expensive…so what is it? (see aPPV slide).
controlled hypotension:
- when aggressively using what type medications?
- with what specific hypertensive crisis (disease)?
- aggressive vasodilation or inotrope therapy
2. pheochromocytoma
