Exam #2: Hemodynamic Monitoring Flashcards
What is a normal stroke volume?
60-150
What is a normal CVP?
2-8
What is a normal PAWP?
6-12
What is normal cardiac output?
4-8
What is a normal stroke volume index
30 - 65
What is a normal cardiac output index?
2.2-4
What is a normal MAP?
70-100 (goal is to be >65)
What is a normal SpO2?
95-100
What is a normal mixed venous O2 sat?
60-80
Hemodynamic Monitoring
-Measurement of pressure, flow, and oxygenation within cardiovascular system
What is the purpose of Hemodynamic Monitoring?
Assesses heart function, fluid balance, and effects of drugs on CO.
Hemodynamic Monitoring includes
- Systemic and pulmonary arterial pressures
- Central Venous Pressure
- Pulmonary Artery Wedge Pressure
- CO and Cardiac Index
- Stroke volume/Stroke volume index
- Stroke volume variation (SVV)
- SaO2 O2 saturation of arterial blood
- Mixed venous oxygenation saturation (SvO2)
What is cardiac output?
Volume of blood pumped by the heart in one minute
What is Cardiac Index?
CO adjusted for body surface area
Stroke volume
Volume ejected with each heartbeat
Stroke volume index
SV adjusted for body size
What is systemic vascular resistance and pulmonary vascular resistance?
Opposition to blood flow by systemic and pulmonary vasculature
What determines SV?
Preload, afterload and contractility
What is preload?
Volume of blood within ventricle at the end of diastole.
*read notes on slide!
PAWP
Reflects left ventricular end-diastolic pressure
CVP
Reflects right ventricular end-diastolic pressure
What is afterload?
- Forces opposing ventricular rejection.
- These include SVR and PVR.
Afterload: SVR and Arterial Pressure indices of
Left ventricular afterload
Afterload: PVR and pulmonary arterial pressure indices of
Right ventricular afterload
Vascular resistance
- Can be systemic or pulmonary
- Reflect afterload
Contractility
- Strength of ventricular contraction
- No direct clinical measure (therefore need to look at PAWP and CO over time)
*Read notes!! Didn’t get to look at them
Principles of Invasive Pressure Monitoring
Equipment must be referenced and zero balanced to environment and dynamic response characteristics optimized
Principles of Invasive Pressure Monitoring: Referencing
positioning transducer so zero reference point is at level of atria of heart or phlebostatic axis
How can you identify the phlebostatic axis?
- Draw two imaginary lines with the patient supine.
- Draw a horizontal line down from the axilla, midway between the anterior and posterior chest walls.
- Draw a vertical line laterally through the fourth intercostal space along the chest wall.
- The phlebostatic axis is the intersection of the two imaginary lines.
*Look at picture
Placing the monitor on the phlebostatic axis
- Mark this location on the patient’s chest with a permanent marker.
- Position the port of the stopcock nearest the transducer level at the phlebostatic axis.
- Tape the transducer to the patient’s chest at the phlebostatic axis or mount it on a bedside pole.
Principles of Invasive Pressure Monitoring: Zeroing
- Confirms that when pressure within system is zero, monitor reads zero.
- Done by opening reference stopcock to room air
- Done with the initial setup and periodically thereafter
Dynamic Response Test (Square Wave Test)
- Optimizing dynamic response characteristics involves checking that the equipment reproduces, without distortion, a signal that changes rapidly.
- Perform a dynamic response test (square wave test) every 8 to 12 hours and when the system is opened to air or the accuracy of the measurements is questioned. It involves activating the fast flush and checking that the equipment reproduces a distortion-free signal.
Arterial Blood Pressure Monitoring
- Various indications when continuous BP measurements useful
- Non-tapered Teflon catheter is typically used to cannulate artery (into peripheral artery)
- Suture in place
- Immobilize insertion site
Components of Pressure Monitoring System
The catheter, shown entering the radial artery, is connected via pressure (nondistensible) tubing to the transducer. The transducer converts the pressure wave into an electronic signal. The transducer is wired to the electronic monitoring system, which amplifies, conditions, displays, and records the signal. Stopcocks are inserted into the line for specimen withdrawal and for referencing and zero-balancing procedures. A flush system, consisting of a pressurized bag of intravenous fluid, tubing, and a flush device, is inserted into the line. The flush system provides continuous slow (approximately 3 mL/hr) flushing and provides a mechanism for fast flushing of lines.
*Look at picture on slide 15
Arterial Pressure Monitoring
Read Notes on Slide 16
What does the diacritic notch indicate?
Aortic valve closure