Methods of distinguishing between vasoconstriction and vasodiltation as a cause of hypotension

• US 20070179384A1
• Filed: 03/04/2005
• Published: 08/02/2007
• Est. Priority Date: 03/05/2004
• Status: Active Grant

• Current Assignee: Atcor Medical Pty Ltd (CardieX Ltd.)
• Original Assignee: Atcor Medical Pty Ltd (CardieX Ltd.)
• Inventors: O'Rourke, Michael
• Granted Patent: US 7,442,169 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis

Abstract

The present invention relates to the use of the arterial pressure waveform recorded invasively or non-invasively, to distinguish between compensatory vasoconstriction with low cardiac output on the one hand from vasodilation from more severe organ damage on the other, as a cause of hypotension in acute emergencies. The waveforms may be subjected to harmonic analysis and the moduli of their harmonic components compared whereby a hypotensive individual can be confirmed to have the higher the first harmonic is considered as having vasoconstriction as a cause of hypotension.

Claims

1. A method for measuring the arterial waveform invasively or non-invasively from a peripheral artery, wherein the waveforms are accurately recorded and secondary pressure waveforms are identified.

2. A method according to claim 1 wherein a series of pressure waveforms are ensemble-averaged into a single waveform to provide consistency of waveform detail.

3. A method according to claim 1 wherein the waveforms are subjected to harmonic analysis and moduli of their harmonic components are compared.

4. A method according to claim 1 wherein a hypotensive individual is confirmed to have the higher (second and above) greater than the first harmonic can be considered as having vasoconstriction as a cause of hypotension.

5. A method according to claim 1 wherein a hypotensive individual in sinus rhythm or without significant arrhythmia is confirmed to have the lowest fundamental harmonic, at heart rate less than 120/min, dominant over all the other harmonics and can be concluded as likely to have vasodilation as the cause of hypertension.

6. A method according to claim 1 wherein, in the hypotensive individual, amplitude of the primary waveform (peak to wave foot) is compared to amplitude of the secondary waveform (secondary peak to wave foot) and the secondary wave confirmed to have amplitude less than 25% of the primary waveform as denoting hypotension due to vasodilation whereas amplitude of the secondary waveform greater than 30% of the primary wave denotes hypotension due to vasoconstriction and acute blood loss, cardiac failure, tamponade or pulmonary embolism.