Hemodynamics Flashcards
Hemodynamic Principles:
Flow of _____ and factors affecting it
Study of _____ circulation
Hemodynamic Principles:
Flow of BLOOD and factors affecting it
Study of BLOOD circulation
Evaluates:
- Intravascular _______ and ______
- Intracardiac _______
- _______ function
These all affect the body’s ability to ensure adequate tissue ________ and _______
Evaluates:
- Intravascular VOLUME and PRESSURES
- Intracardiac PRESSURES
- CARDIAC function
These all affect the body’s ability to ensure adequate tissue PERFUSION and OXYGENATION
Invasive vs Non-Invasive HD Monitoring
Non-invasive: no device inserted into the body - does not breach skin (BP, HR, O2, U/O, JVD)
Invasive: Breach of skin (Art line, pulm-art catheter, CVP)
Determinants of Oxygen Delivery
Cardiac output x Oxygen Content
- Cardiac output: HR x SV (preload, afterload, contractility)
- Oxygen content: oxygen saturation & hemoglobin
Cardiac Output:
Amount of blood pumped out of the ____ in a _____
CO: ____ x ____
HR: # of _____ of the _____ in a _____
SV: Amount of blood ___ out of the ___ per _____. It is the difference between ______ and ______
Cardiac Output:
Amount of blood pumped out of the LV in a MINUTE
CO: HR x SV
HR: # of CONTRACTIONS of the HEART in a MINUTE
SV: Amount of blood PUMPED out of the LV per BEAT. It is the difference between EDV and ESV
How to calculate EF?
Normal EF?
SV / EDV x 100
50-70%
3 factors that affect stroke volume?
Preload, afterload, and contractility
Contractility:
AKA _______
Ability of the cardiac muscle to _____
Strength of the cardiac muscle to ____ blood from the _____
Primary parameter that affects _____
Increased _______ = Increased ______ = Decreased _______
Contractility:
AKA INOTROPY
Ability of the cardiac muscle to CONTRACT
Strength of the cardiac muscle to PUMP blood from the VENTRICLES
Primary parameter that affects ESV
Increased CONTRACTILITY = Increased SV = Decreased ESV
Medications that Affect Contractility:
Positive Inotropes:
Negative Inotropes:
Digoxin, dopamine, atropine
BB, BBC, lidocaine, adenosine
Electrolytes that increase contractility
Electrolytes that decrease contractility
Increase: HyperMg, HyperCa
Decrease: HypoMg, HyperK, HypoNa
How does HR affect contractility?
Increased HR increases contractility, but sustained tachycardia leads to decompensation - decreased contractility
Vagal stimulation will ________ contractility
Decrease
EDV
ESV
SV
EDV - Amount of blood that fills the ventricles prior to contraction (affects preload)
ESV - Amount of blood that remains in the ventricles after contraction (affected by afterload)
Difference between EDV - ESV (amount of blood ejected)
Ie. If EDV is 100cc and SV is 60cc, then the ESV is 40cc
What is preload?
Degree to which cardiac muscle fibres are ______ prior to _________
Anything that affects ______ will affect preload
Increased ____ = increased ______ = increased _____ = increased ______ = increased _______ (up to a point)
The amount of stretch caused by the EDV
Degree to which cardiac muscle fibres are STRETCHED prior to CONTRACTION
Anything that affects VENOUS RETURN will affect preload
Increased EDV = increased STRETCH = increased PRELOAD = increased CX = increased CO (up to a point)
Frank-Starling Mechanism
- Force of cardiac contraction is directly ______ to the length of the muscle fibre
- The greater the _______, the stronger the ______ = increased ________
- However, after a certain threshold, the stretch will _______ contractility
Frank-Starling Mechanism
- Force of cardiac contraction is directly PROPORTIONAL to the length of the muscle fibre
- The greater the STRETCH, the stronger the CX = increased SV
- However, after a certain threshold, the stretch will DECREASE contractility
Afterload:
The __________ or __________ ventricles must overcome to pump blood out
LV: ______
RV: ______
Any condition that increases the resistance (afterload) will require more ____ to open the semilunar valves and pump blood out
_____ in afterload = _______ SV = ______ ESV
_____ in afterload = _______ SV = ______ ESV
Afterload:
The RESISTANCE or PRESSURE ventricles must overcome to pump blood out
LV: SVR
RV: PVR
Any condition that increases the resistance (afterload) will require more FORCE to open the semilunar valves and pump blood out
INCREASE in afterload = DECREASED SV = INCREASED ESV
DECREASE in afterload = INCREASE SV = DECREASED ESV
How do hyper- and hypo-volemia affect afterload?
How do hyper- and hypo-tension affect afterload?
Hypervolemia = increased AL = decreased SV
Hypovolemia = decreased AL = increased SV
Same with BP
Ventricles create very ______ pressure vs the atria which has very _____ pressure
The bigger the difference between the two - the _______ a litre of blood will flow through your body
Ventricles create very HIGH pressure vs the atria which has very LOW pressure
The bigger the difference between the two - the FASTER a litre of blood will flow through your body
The body maintains homeostasis, by monitoring the _____
The MAP needs to be high enough to ensure sufficient driving ___________ to deliver oxygenated blood to the body’s tissues
The body maintains homeostasis, by monitoring the MAP
The MAP needs to be high enough to ensure sufficient driving PRESSURE to deliver oxygenated blood to the body’s tissues
What does the QRS complex represent?
Ventricular contraction - systole
What does the time between each R-R represent?
Diastole
Normal MAP
65-110 mmHg
___________ respond to MAP, not ____ or ____ pressures
BARORECEPTORS respond to MAP, not SBP or DBP pressures
Is MAP a sufficient indicator of perfusion?
NO - SBP and DBP also need to be monitored in conjunction with MAP
What are the two main factors that affect MAP?
CO and TOTAL PERIPHERAL RESISTANCE (AFTERLOAD)
Indications for arterial line
BP monitoring
Admin vasoactive meds
Frequent ABG monitoring
Arterial Line sites: Radial vs Femoral - which is preferred?
Radial
3 Elements of Arterial Monitoring
Where do you zero the transducer?
Pressure tubing
Transducer
Monitor
Zero at the phlebostatic axis - 4ICS
Arterial Pressure Waveform:
Arterial pressure measures the ejection of blood from the ___, out the __ and into the _______ system
Blood ejected from the ____, generates pressure in a _________ manner
3 Components of Arterial Waveform:
1) Anacrotic limb: ________ upstroke - increase in pressure caused by blood ejected from ____ during ____. Reaches a peak = _______
2) Dicrotic limb: _______ decline - as pressure falls, aortic valve closes marking the end of ventricular ______ and onset of ________. As ______ progresses, the pressure falls to its lowest level = _______
3) Dicrotic notch: ______ of aortic valve
4) One wave = one ________ cycle
Arterial Pressure Waveform:
Arterial pressure measures the ejection of blood from the LV, out the AORTA and into the ARTERIAL system
Blood ejected from the AORTA, generates pressure in a PULSATILE manner
3 Components of Arterial Waveform:
1) Anacrotic limb: SYSTOLIC upstroke - increase in pressure caused by blood ejected from LV during SYSTOLE. Reaches a peak = SBP
2) Dicrotic limb: SYSTOLIC decline - as pressure falls, aortic valve closes marking the end of ventricular SYSTOLE and onset of DIASTOLE. As DIASTOLE progresses, the pressure falls to its lowest level = DBP
3) Dicrotic notch: CLOSURE of aortic valve
4) One wave = one CARDIAC cycle
What term is used to describe the difference between SBP and DBP?
Pulse Pressure
What does increased pulse pressure mean?
Increased blood flow - it is the force the heart generates each time it contracts
__________ stimulation (____) is always first and then the _______ waveform
Ie - the peak ________ pressure occurs immediately following ventricular depolarization (____)
ELECTRICAL stimulation (QRS) is always first and then the ARTERIAL waveform
Ie - the peak SYSTOLIC pressure occurs immediately following ventricular depolarization (QRS)
Fast-Flush Test:
Normal: __-__ bounces
Underdamped: _____ SBP, _____ bounces, narrow/pointy waveform
Overdamped: _____ SBP, no more than ____ bounce, wide/round waveform
Fast-Flush Test:
Normal: 1-2 bounces
Underdamped: OVERESTIMATES SBP, 3 bounces, narrow/pointy waveform
Overdamped: UNDERESTIMATES SBP, no more than 1 bounce, wide/round waveform
Is cuff pressure and arterial pressure related?
Non-invasive measures ________. Invasive measures __________.
When is cuff pressure indicated?
No, there is no relationship.
Non-invasive measures FLOW. Invasive measures PRESSURE.
Insertion of art line + if art line becomes unreliable/dislodged
CVP: Pressure in the ______. Measured at the junction of the ____ & ______.
Represents the driving force for filling the ______
Used as a marker of __________ or ________
CVP: Pressure in the RA. Measured at the junction of the SVC & RA.
Represents the driving force for filling the RA/RV
Used as a marker of FLUID VOLUME or PRELOAD
CVP Waveform Components:
A - “______” - ____ contraction + correlates with ____-_____ on ECG
X - atrial ________
C - “_________” - closure of the ______ valve as ________ contract (_____ complex on ECG)
V - Blood filling the ________, just after the ___-______ on ECG
Y - _______ valve opening and blood filling the ventricles
CVP Waveform Components:
A - “ATRIUM” - ATRIAL contraction + correlates with P-WAVE on ECG
X - atrial RELAXATION
C - “CUSP CLOSURE” - closure of the TRICUSPID valve as VENTRICLES contract (QRS complex on ECG)
V - Blood filling the ATRIUM, just after the T-WAVE on ECG
Y - TRICUSPID valve opening and blood filling the ventricles
CVP Abnormalities:
Loss of an ‘a’ wave: no _______ __________
Dominant ‘a’ wave: increased _______ of flow from the atrium to the ventricle. Seen with _____ and ______ stenosis
Steep X and Y descent: increased ______ pressures
Fused “a” and “c” waves: atrial _____ and ventricular ____ occur at _____
Fused “c” and “v” waves: backflow of blood out of the right ________
CVP Abnormalities:
Loss of an ‘a’ wave: no ATRIAL CX
Dominant ‘a’ wave: increased RESISTANCE of flow from the atrium to the ventricle. Seen with PULMONARY and TRICUSPID stenosis
Steep X and Y descent: increased ATRIAL pressures
Fused “a” and “c” waves: atrial CX and ventricular CX occur at SAME
Fused “c” and “v” waves: backflow of blood out of the right VENTRICLE
How to measure CVP:
1) Find top of __ wave
2) Find bottom of __ descent
3) Add values and / by ____
How to measure CVP:
1) Find top of A wave
2) Find bottom of X descent
3) Add values and / by 2
Which are the lowest points of pressure?
Which are the highest points of pressure?
Lowest - RA/LA
Highest - Pulmonary artery and Aorta
What does the surface area under an arterial waveform represent?
MAP
Can you use a femoral CVAD to obtain a CVP reading?
Yes - but the reading will not be as accurate as the tip will be too far from the RA to provide pressure readings
What 2 things might be ordered to help lower a patient’s preload?
Diuretics
Fluid Restriction
In what situations can venous return be greater than cardiac output?
NEVER - venous return must always = CO
