Hemodynamic Monitoring Flashcards
Cardiac Output = ___ x ____
HR x SV
heart rate
stroke volume = amount of blood ejected by ventricle w/ each contraction
Normal cardiac output value
4.0 to 8.0 L/min
what is cardiac index?
it is the CO that has been adjusted to individual body size based on BSA (body surface area)
CI = CO divided by BSA
Normal cardiac index value
2.5 to 4.3 L/min/m^2
Normal stroke volume
60 to 100 ml/beat
Stroke volume is dependent on what 3 things
preload, afterload, and contractility
What are the two categories of impairment to the Left ventricle causes decreased stroke volume (which also decreases cardiac output)
1- inadequate ventricle filling
2- inadequate ventricle emptying
Common causes of an increase in pulmonary vascular resistance (PVR)
- pulmonary hyptertension
- pulmonary embolism
- hypoxia
- end stage COPD (cor pulmonale)
Factors that affect contractility (bedsides preload & afterload)
- electrolyte levels
- myocardial oxygenation (ischemia)
- amount of functional myocardium (infarction, cardiomyopathy)
- postive/negative inotropic medications
Arterial catheter (“A-line”)
- how the tubing differs from normal IV tubing
- what type of solution can be used
- how much pressure mm Hg is placed on the IV bag
- most common sites
- it is stiff and noncompliant and is kept as short as possible (no more than 3-4 ft)
- most common- NS but D5W can be used
- 300 mm Hg
- radial- most common; also brachial, axillary, femoral, or pedal
Where is the phlebostatic axis?
The intersection between the 4th ICS and half the AP diameter of the chest
Valsalva maneuver examples
- excessive bearing down during bowel movement
- vomiting
- coughing
- suctioning
Medications that decrease HR (negative chronotropic)
- digitalis
- BB’s
- Calcium channel blockers
- phenlyephrine
Physiologic causes of increased HR
- stress
- anxiety
- pain
- conditions that result in release of catecholamines: hypovolemia, fever, anemia, hypotension
Medications that have direct positive chronotropic effect
epinephrine, dopamine
Two most common causes of low stroke volume
- hypovolemia
- LV dysfunction
What is a normal Ejection Fraction (EF) and how can one measure the EF?
- > 60%
- can be evaluated with a PA catheter or an echocardiogram
3 Etiologies of RV (right ventricular) failure
1) intrinsic disease ie RV infarct, cardiomyopathy
2) secondary factors that increase PVR (ie pulm artery HTN, PE, hypoxemia, COPD, acute ARDS, sepsis)
3) severe LV dysfunction ie: mitral stenosis/insufficiency or LV failure
Normal preload in RV vs LV
Normal RV preload: 2 - 8 mm Hg –> aka RAP
Normal LV preload: 8 - 12 mm Hg –> aka LAP or PAOP/PCWP/PAWP
How to measure preload in RV vs LV
RV: preload measured w/ CVP catheter &/or PA catheter
LV: preload measured w/ PA catheter
3 Factors that alter vascular resistance
1) length of a vessel (constant)
2) viscosity of blood (usually constant)
3) diameter/radius of the vessel
What are common causes of increased Pulmonary vascular resistance (PVR) and which part of the heart does an elevated PVR cause strain on?
- common causes of increased PVR= pulmonary HTN, hypoxia, end stage COPD (cor pulmonale), PE
- causes strain on the R ventricle
Normal range for mixed venous oxygen saturation
60 - 80%
