Term
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Definition
Method commonly used when a pulomnary artery catheter is in place
Depends on the Stewart-Hamilton Formula |
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Term
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Definition
| amount of injected indicator/area of dilution curve |
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Term
| The introduction of the Cold Injectate |
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Definition
| Causes a rapid upslope to a peak, a gradual downslope, and an exponential decay of the thermal signal |
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Term
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Definition
| Begins integration of the area under the TD curve unitl the exponential decay reaches a valve of about 30%, and extrapolates the exponential decay to baseline in order to minimize artifacts due to recirculation of the indicator |
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Term
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Definition
Reduced Volume of Injectate
Slow Injection of Injectate
Use of warm indicator
Tricuspid regurgitation
Assumed precision is +-20% |
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Term
| Slow Injection of Injectate |
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Definition
| Allows Tissue Warming of Solution |
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Term
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Definition
| Usually not a problem unless well above room temperature |
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Term
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Definition
+-20%
Repeated testing can improve precision |
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Term
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Definition
| Possible with a heating Probe built into the PA catheter |
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Term
| Thermodilution can also be Accomplished |
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Definition
| With a CVP and an aortic thermistor placed via femoral artery |
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Term
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Definition
Compares end tidal carbon dioxide partial pressure obtained during a non-rebreathing period with that obtained during a subsequent rebreathing period
Measures pulmonary capillary blood flow- difficulty with presence of significant shunting
Accuracy of this technique remain limited and is currently not recommended as a guide to fluid therapy |
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Term
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Definition
| The degree of accumulation and subsequent removal of CO2 correlates with cardiac output |
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Term
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Definition
Doppler probe is place to assess diameter of aorta and measured flow velocity
Assumes a fixed percentage of CO is directed to the head and upper extremity circulation
Requires proper placement of probe |
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Term
| Requires Proper Placement of Probe |
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Definition
Probe angulation cause falsely low readings
Significant user experience is required |
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Term
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Definition
Based on the relationship among blood pressure, SV, arterial compliance, and SVR
The SV or CO can be calculated from the aterial pressure waveform if the arterial compliance and SVR are known
Initial calibration with a dilution technique is often required |
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Term
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Definition
| Becoming available, but experience is limited |
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Term
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Definition
Application of a high-frequency electric current of known amplitude and frequency across the thorax and measure changes in voltage (amplitude of the returning signal compared with the intial signal)
The instantaneous rate of the change of impedence is believed to be related to the instantaneous blood flow in the aorta
Accuracy of this technique has not been acceptable, although improved algorithms are being developed |
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Term
| Bioreactance (Cheetah System) |
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Definition
Measures the 'bioreactance' or phase shift in voltage across the thorax
This is truly non-invasive system superior accuracy |
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Term
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Definition
| Can be described as an electric circuit with a resistor (R) and a capacitor (C), which together create the thoracic impedance |
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Term
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Definition
| Determine the 2 components of impendance, which are amplitude (a), the magnitude of the impedance (measured in ohms); and phase (phi), the direction of the impedance (measured in degrees) |
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Term
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Definition
| Occur only as the result of pulsatile flow |
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Term
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Definition
High frequency (75 kHz) sine wave generator and 4 dual electrodes
One electrode is used by the high-frequency current generator to inject the high-frequency sine wave into the body, whereas the other electrode is used by the voltage input amplifier
Two electrodes are placed on the right side of the body, and 2 electrodes are placed on the left side of the body |
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Term
| The electrodes on a given side of the body |
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Definition
| Are Paired, so currents are passed between the outer electrodes of the pair, and voltages are recorded form between the inner electrodes |
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Term
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Definition
| Determined separately from each side of the body, and the final noninvasive CO measurement signal is obtained by averaging these 2 signals |
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Term
| The system's signal processing unit |
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Definition
Determines the relative phase shift between the input and output signals
The peak rate of change is proportional to the peak aortic flow during each beat |
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