1-8: Hemodynamic Monitoring Flashcards
What is the most important aspect of hemodynamic monitoring?
determination of the CO
What is stroke volume
the amount of blood ejected from the ventricles in each heartbeat
What can affect the stroke volume?
- cardiac contractility (ejection fraction)
- preload
- afterload
What is preload
also known as left ventricular end diastolic pressure (LVEDP) or CVP (RVP)
- the amount of ventricular stretch at the end of diastole
What is afterload
also known as systemic vascular resistance (SVR)
- the amount of resistance the heart must overcome to open the aortic valve and push blood into systemic circulation
What is cardiac output
the volume of blood ejected by the heart per minute
What is the normal range for cardiac output?
4-8 L/min
What is the equation for CO
SV x HR
What are some causes of elevated CO?
- stimulation of the sympathetic nervous system (pain, epi)
- positive inotropic stimulation
- hyperthyroidism
- hypervolemia
- anemia
What are some causes of decreased CO?
- an increased HR that doesn’t allow for adequate preload ( >150)
- decreased HR
- decreased myocardial contractility
- increased afterload
Why does increased afterload decrease CO?
- afterload is SVR
- the pressure in the ventricle (4-16) must be higher than the pressure in the aorta (80) to get forward flow
- afterload is anything that makes it harder to get blood OUT of the heart.
- Increasing afterload (SVR) is having a higher diastolic BP
- if your ventricle has to work harder to push blood out of the heart, ultimately LESS blood will be let out.
What is cardiac index?
CO / BSA
What is the normal range for cardiac index?
2.5 - 4 L/m/m2
and these are hard values, if it hits 2.4, as a medic you need to do something
What value will cardiac index fall below in cardiogenic shock?
1.8
What is SvO2 and what is the range?
The saturation of hemoglobin on the venous side
normal saturation is 65-75%
What do low and high levels of SvO2 mean?
low: more oxygen is jumping off at the tissues, which indicates a decreased tissue perfusion issue.
high: less oxygen is jumping off at the tissues, indicates decreased O2 consumption at the tissue level
What affects preload?
- intravascular volume
- venous tone (size of the pipes)
Right ventricular preload is the same as CVP, so has a range of:
2-8 mmHg
Left ventricular pressure is the same as:
LVEDP
What is the range for SVR?
800-1200
What is the value for pulmonary vascular resistance?
<250 dynes/sec/cm5
Can a single measurement be used in isolation to assess hemodynamics?
no, silly
What are the parameters of hypotension?
- SBP < 90
- SBP decrease of >40 under baseline
- MAP <65
Is it possible for a patient to have a normal BP yet have hypoperfusion and be in shock?
yes
What is the formula for shock index?
HR / SBP
What is the normal range for shock index?
0.5 - 0.7
What is the value of shock index that indicates early circulatory collapse and shock?
0.9
skin discoloration on what part of the body indicates poor perfusion (for adults vs. kids)
- adults: over knee/leg
- kids: hands and feet
How many lumens does the Swan cath have and what are they?
4 lumens
1. proximal ( right atrial)
2. distal ( pulmonary artery)
3. balloon inflation port
4. infusion port
Transducers must be calibrated to:
ambient air pressure
What does the transducer ned to be placed level with? What is another name for it?
transducer must be level with the right atrium, also called the phlebostatic axis
How does the pressure reading correlate to the position of the transducer?
the higher the transducer, the falsely lower the pressure
the lower the transducer, the falsely higher the pressure
How should the stopcock be when zeroing the transducer?
“off to the patient, open to the air”
When should you zero the transducer?
- whenever a reading is taken
- insertion
- change in the pts position
under what conditions do you leave the swan balloon inflated?
none, you silly goose
What are some complications that could occur DURING Swan catheter placement?
- dysrhythmia
- pneumothorax
- arterial puncture
- mechanical injury (RV puncture)
- kinking of the catheter
What are some complications that could occur AFTER Swan catheter placement?
- forward catheter displacement (aka spontaneous wedging)
- backward catheter displacement (tip in RV)
- pulmonary artery rupture
- pulmonary artery infarction
How can spontaneous wedging be seen and avoided?
can be seen: waveform change, lose dichrotic notch
prevented by: taping a reference strip to the monitor for transport
What should you do if you suspect forward catheter displacement?
- check to make sure the balloon is deflated
- check for effect of position change (raise arm above head and cough)
- turn the pt onto their left side
- call the physician
what is the main concern regarding backward cath displacement of a swan catheter?
The catheter needs to be repositioned because catheter whip might cause arrhythmias
What are the parts of a CVP waveform and what do they mean?
(be able to draw it out and label it)
“a” - produced when the atria contract.
this is the beginning of the cycle
“c” - caused by the closure of the tricuspid valve
“x” and “y” - atrial diastole
“v” - venous filling of right atrium
What is the CVP and ranges
Central venous pressure
2 - 8
What is the RAP and ranges
right atrial pressure
2 - 8
What do the CVP and RAP reflect?
the right ventricular end-diastolic pressure or PRELOAD
What causes elevated CVP/RAP?
anything that blocks forward flow
- right sided heart failure
- cardiac tamponade
- pulmonary hypertension
- volume overload
- PPV
Causes of low CVP/RAP
- volume depletion
- vasodilation
- venous vasodilator
right ventricular pressure (RVP) normal range
0 - 8
What causes elevated RVP?
** anything that causes higher pressures downstream of the RV**
- pulmonary disease
- hypoxemia
- chronic heart failure
- RV failure or infarction
- ventricular septal defect
Causes of low RVP
- hypovolemia
- vasodilation
normal values of PAP
5 - 15
Causes of elevated PAP
- hypervolemia
- pulmonary hypertension
- PPV
- cardiac tamponade
- left ventricular failure
Causes of low PAP
- hypovolemia
- vasodilation
what is the most amount of air used to inflate the swan catheter and when do you stop inflating it?
1.5 mL
stop inflating when the waveform changes from PA to PAWP
Wedging should last no longer than _____
15 seconds
What is the range for wedge / PAWP / PCWP / PAOP?
4 - 12 mmHg
wedge pressure: in spontaneously breathing patients, inspiration is a ____ in pressure and expiration is a ____ in pressure
fall, rise
Where should the wedge pressure be taken?
at end expiration pressure (it is as close as it will get to atmospheric pressure and therefore provides the most accurate reading)
Causes of elevated wedge
blockage of forward flow
- PPV
- hypervolemia
- left ventricular failure (CHF)
- severe aortic stenosis
Causes of low wedge
- hypovolemia
- vasodilation
All ranges:
MAP
CVP
PAS
PAD
PAWP
CO
CI
RVP
PVR
SVR
MAP (mean arterial pressure) 70-100
CVP (central venous pressure) 2-8
PAP (pulmonary arterial pressure)
- systolic: 15-30
- diastolic: 5-15
PAWP (wedge) 4-12
CO (cardiac output) 4-8 L/min
CI (cardiac index) 2.5-4
RVP (right ventricular pressure)
- systolic: 15-30
- diastolic: 0-8
PVR (pulmonary vascular resistance) < 250
SVR (systemic vascular resistance) 800-1200
The causes of a dampened waveform are the same for an art line and swan cath except for one thing, what is it?
A spontaneous wedge can occur in a swan, causing dampened waveform
what is the treatment for a dampened waveform on swan?
- pull cath back to RA if it has spontaneously moved forward
- pull cath back to PA if waveform indicates a spontaneous wedge and the balloon isn’t inflated
Causes of right ventricular waveform:
- if the cath gets pulled to the right ventricle
- RV waveform looks similar to v-tach
Causes of no waveform:
- stopcock turned off to the pt
- catheter tip is clotted
- monitor or system is set up incorrectly/ equipment not working
Which intercostal space is the phlebostatic axis located
4th
which reading indirectly reflects left atrial pressure and LVEDP?
wedge
