Venous pressure measurement apparatus

Abstract

A non-invasive venous pressure measurement apparatus is provided, including: a first cuff attached to a portion including a vein and an artery in a living body; a pressure control unit that changes a first applied pressure applied by the cuff to the portion; a pulse wave detection unit that detects a pulse wave from a pressure received by the cuff from the portion; another pulse wave detection unit that detects another pulse wave including at least an arterial pulse wave in another portion of the living body; an analyzing unit that analyzes a correlation between the two pulse waves, which are changed as the applied pressure is changed by the pressure control unit changes; and a venous pressure calculation unit that calculates a venous pressure based on the applied pressure and a result of analysis by the analyzing unit.

What is claimed is: 
     
       1. A venous pressure measurement apparatus comprising:
 a first cuff configured to be attached to a first portion including a vein and an artery in a living body; 
 a pressure control unit that changes a first applied pressure applied by said first cuff to said first portion by sending a flow of air to the first cuff; 
 a first pulse wave sensor that detects a first pulse wave from the pressure received by said first cuff from said first portion; 
 a second pulse wave sensor configured to detect a second pulse wave including at least an arterial pulse wave in a second portion different from said first portion of from said living body; 
 a pressure waveform analyzing processor, comprising an analyzing unit that analyzes differences between said second pulse wave detected by said second pulse wave sensor and said first pulse wave detected by said first pulse wave sensor as a correlation a difference between the first pulse wave and the second pulse wave, which are changed as said first applied pressure is changed by said pressure control unit; and 
 a venous pressure calculation unit that calculates a venous pressure based on said first applied pressure and a result of analysis by said analyzing unit. 
 
     
     
       2. The venous pressure measurement apparatus as claimed in  claim 1 , wherein
 said venous pressure calculation unit calculates said venous pressure based on the first applied pressure when said correlation is minimized as a result of the analysis by said analyzing unit.   
     
     
       3. The venous pressure measurement apparatus as claimed in  claim 1 , wherein said analyzing unit obtains a venous pressure wave component by subtracting a component correlated with said second pulse wave from said first pulse wave. 
     
     
       4. The venous pressure measurement apparatus as claimed in  claim 3 , wherein
 the component correlated with said second pulse wave is an arterial pulse wave component of said first pulse wave calculated from an arterial pulse wave component of said second pulse wave and said first pulse wave. 
 
     
     
       5. The venous pressure measurement apparatus as claimed in  claim 3 , wherein
 said venous pressure calculation unit calculates said venous pressure based on said first applied pressure when an amplitude of said venous pulse wave component is maximized. 
 
     
     
       6. The venous pressure measurement apparatus as claimed in  claim 1 , wherein
 said first cuff is configured to be attached to an upper arm in the vicinity of a neck or an axilla. 
 
     
     
       7. The venous pressure measurement apparatus as claimed in  claim 1 , wherein
 said second pulse wave sensor is a second cuff configured to be attached to said second portion distal to said first cuff with respect to the heart of said living body, and   said pressure control unit further controls a second applied pressure applied by said second cuff to said second portion.   
     
     
       8. The venous pressure measurement apparatus as claimed in  claim 7 , wherein
 said first cuff is configured to be attached to an upper arm in the vicinity of an axilla, and said second cuff is configured to be attached to a portion distal to said first cuff with respect to the heart in the upper arm where said first cuff is attached.   
     
     
       9. The venous pressure measurement apparatus as claimed in  claim 1 , wherein
 said second pulse wave sensor is a photoplethysmographic pulse wave sensor.   
     
     
       10. The venous pressure measurement apparatus as claimed in  claim 7 , wherein
 said pressure control unit controls such that said first applied pressure of said first cuff is equal to said second applied pressure of said second cuff.   
     
     
       11. The venous pressure measurement apparatus as claimed in  claim 7 , wherein
 said pressure control unit maintains said second applied pressure constant at a pressure equal to or higher than a venous pressure anticipated in advance.   
     
     
       12. The venous pressure measurement apparatus as claimed in  claim 1 , wherein the pressure waveform analyzing processor, further comprises a phase correction unit that performs correction to reduce a phase difference between said first pulse wave and said second pulse wave. 
     
     
       13. The venous pressure measurement apparatus as claimed in  claim 7 , further comprising:
 a third cuff configured to be attached between said first cuff and said second cuff which are each configured to be attached to the same upper arm to measure an arterial pressure,   wherein these three cuffs are integrated into a single unit.   
     
     
       14. The venous pressure measurement apparatus as claimed in  claim 1 , wherein
 said venous pressure calculation unit corrects the calculated venous pressure by a relation between said venous pressure measured in advance and said first applied pressure. 
 
     
     
       15. A venous pressure measurement method comprising:
 changing a pressure applied by a cuff, which is adapted to be attached to a portion including a vein and an artery in a living body, to the portion;   detecting a first pulse wave from the pressure received by the cuff from the portion;   detecting a second pulse wave from the living body;   analyzing a difference between the first pulse wave and the second pulse wave, which are changed as the pressure is changed; and   calculating a venous pressure based on the pressure and a result of analysis.