Non-Invasive Central
Venous Pressure Monitor (CVP)
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Hardware for neck
inductive plethysmograph, the sensor utilized, RespiTrak, has 510(k) approval
for marketing. Software requires submission to FDA.
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CVP measurement
based upon well-known clinical observation that raising level of upper
torso of supine subject causes collapse of internal jugular veins.
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Collapse point
is the height above mid-chest level that the venous pulse measure with
NIP is replaced by an arterial pulse.
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Scientific study
has established validity to invasive measurement of CVP (Chest 1991;100:371).
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Non-Invasive Monitor
of Ventricular Volume Curves (Thoracocardiography [TCG])
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Uses inductive
plethysmographic band placed around chest below xiphoid process as sensor.
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Depicts ventricular
volume curve which strongly resembles ventricular volume curve obtained
simultaneously with Automatic Border Edge Detection Echocardiogram.
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Measures changes
in stroke volume & cardiac output.
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Provides measures
of systolic & diastolic function.
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Four papers
on TCG technology in peer-reviewed journals (Chest 1991;99:613;
Chest 1991; 99:896; Chest 1994;106:1668; Am.J.Respir.Dis Crit.Care
Med. 1997;155:26).
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TCG compares well
to thermodilution determined cardiac output in critically ill ICU patients
over several hours.
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TCG compares well
to systolic time intervals obtained from carotid pulse.
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Derivative of
diastolic portion of ventricular volume curve (TCG) corresponds to Echo-Doppler
E&A waves; deceleration time of E wave correlates with Pulmonary Capillary
Wedge Pressure. Therefore, TCG might be a non-invasive alternative to Swan-Ganz
catheter!
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