Ch 6 Pinsky Hemodynamic Monitoring Flashcards
What is the purposes of hemodynamic monitoring?
To characterize the cardiovascular state of the individual, identify cardiovascular insufficiency and its most probable causes, and monitor response to targeted therapies aimed at restoring cardiovascular sufficiency.
T or F: The basic tenet of resuscitation is to provide adequate oxygen (02) delivery (DO2) to meet metabolic demand and reverse any existing tissue hypoperfusion.
True
T or F: In general, noninvasive continuous monitoring, if available and accurate, is preferred to invasive intermittent monitoring.
True
What are the principal hemodynamic monitoring biomarkers?
Arterial pressure, central venous pressure, pulmonary artery pressure and its occlusion pressure, estimates of cardiac output (CO), and the various ways of assessing oxygenation.
What is required for hemodynamic monitoring?
An open tubing system without obstruction at the tip (often due to blood clots), elimination of air bubbles in the tubing that dampen the signal, and hydrostatic zeroing to the isosbestic point (5 cm below the manubrium sterni) in order to measure dynamic and mean pressure and arterial pressure-derived estimates of CO.
What is the primary force driving blood pinto the tissues?
Arterial blood pressure.
What is Systolic pressure?
The maximum pressure during ventricular ejection/
What is Diastolic pressure?
The lowest pressure in the blood vessels between heartbeats during ventricular filling as the stored arterial blood runs off into the periphery.
What is the difference between the systolic and diastolic pressures called?
Pulse pressure and is determined by left ventricular stroke volume, central arterial capacitance, and to a certain extent the rate of LV ejection.
T or F: Systolic pressure usually decreases from central to peripheral sites whereas diastolic pressure increases slightly.
False. Systolic pressure usually increases from central to peripheral sites whereas diastolic pressure decreases slightly.
What is the primary driving pressure for cerebral and peripheral organ perfusion?
Mean Arterial Pressure (MAP)
Mean Arterial Pressure (MAP) is estimated how?
As the sum of diastolic pressure plus one-third of the pulse pressure.
What is the most common way of measuring arterial pressure?
Sphygmomanometer
What are some issues of Sphygmomanometer use?
It often gives slightly higher systolic pressure and lower diastolic pressure than those reported from simultaneous direct measurement using an intra-arterial catheter.
T or F: Intra-arterial catheterization is the reference method for blood pressure measurement and should be used in all hemodynamically unstable patients in whom accurate and continuous measures of arterial pressure and required.
True.
What does intra-arterial catheterization provide?
Instantaneous measures of MAP, arterial pulse pressure, pulse pressure variation, and CO with newer transducer technologies.
What does hypotension do to a person’s body?
Decreases oxygen perfusion pressure and blood flow, stimulating a sympathetic response to increase vasomotor tone, heart rate, and contractility.
What is a reasonable target MAP?
Between 90-60 mm Hg, although the optimal MAP will vary depending on the underlying cause of hemodynamic instability. When MAP decreases below 65 mm Hg in a previously nonhypertensive patient, organ perfusion becomes compromised.
What is the target MAP for traumatic brain injury?
90 mm Hg
Is it okay to use CVP for assessing intravascular volume?
No, CVP is not a measure of central blood volume nor can its values be used to determine whether a patient will be volume responsive.
What do high CVP values (> 12 mm Hg) indicate?
A larger than normal mean systemic pressure allowing an adequate perfusion pressure gradient to sustain venous return.
What is a noninvasive way to measure CVP?
Through inspection of the jugular venous pulsation.
Where is CVP measure from?
The IJ or subclavian vein.
All intrathoracic vascular pressures should be measured when?
At end-expiration to minimize the pressure artifact.
How is Pulmonary artery pressure measured?
It is measured from the tip of a nonoccluded pulmonary artery catheter once this catheter has been floated past the pulmonic valves into the main pulmonary arteries.
What is pulmonary artery occlusion pressure used for?
To assess PVR, pulmonary edema, intravascular volume status and LV preload, and LV performance.
What happens with increased pulmonary arterial pressure?
Increased pulmonary arterial pressure impedes right ventricular ejection, causing RV dilation and decreased CO.
What contributes to pulmonary hypertension?
An increase in pulmonary vasomotor tone, pulmonary vascular obstruction or passive increases in Ppao due to LV failure.
What causes pulmonary edema?
Elevations of pulmonary capillary pressure, increased capillary or alveolar epithelial permability, or a combination of both.
What are the primary determinates of LV performance?
Preload (LV end diastolic volume), afterload (LV wall stress), heart rate, and contractility.
What are the most commonly used noninvasive techniques to measure cardiac output?
Echocardiography, pulsed esophageal Doppler, and continuous wave suprasternal notch ultrasound.
How does Esophageal Doppler ultrasound work?
It uses an esophageal probe similar in size to a nasogastric tube to measure descending aortic flow as it parallels the esophagus. A Doppler transducer probe is inserted orally or nasally to midthoracic level and rotated until the probe senses a characteristic aortic velocity signal profile.
How does Transcutaneous Doppler US work?
It uses a handheld probe placed at the suprasternal notch with the transducer aimed downward at the aortic valve. This technique is easy to learn and gives accurate measures of LV stroke volume and CO.
What is the primary invasive measurement used to measure CO?
Pulmonary artery catheter.
T or F: An increase in CO of greater than 15% after a fluid challenge has been considered the gold standard reflecting fluid responsiveness.
True.
Hypoxemia is usually defined as a SPO2 less than ___.
90%
