Bladder-based cuff for measuring physiological parameters and method of measuring physiological parameter using same

• US 20080132796A1
• Filed: 07/24/2007
• Published: 06/05/2008
• Est. Priority Date: 10/29/2003
• Status: Active Grant

• Current Assignee: Hema Metrics, LLC (Fresenius SE & Co. KGaA)
• Original Assignee: Hema Metrics, LLC (Fresenius SE & Co. KGaA)
• Inventors: Cox, Douglas L., Miller, David R., Bell, David A., Law, Perry N.
• Granted Patent: US 7,708,694 B2
• Time in Patent Office: Days
• US Class Current: 600/499
• CPC Class Codes: A61B 5/02233 Occluders specially adapted therefor tourniquets A61B17/132
• CPC Class Codes: A61B 5/02241 of small dimensions, e.g. adapted to fingers
• CPC Class Codes: A61B 5/02422 within occluders

Abstract

A cuff for measuring volume and change in volume of a body appendage includes a hollow, rigid tube having an inner surface; and a bladder having an inner surface and an outer surface, the ends of the bladder being sealed to the ends of the tube to create an enclosed internal volume between the inner surface of the bladder and the inner surface of the tube and an external volume defined by the outer surface of the bladder and surrounded by the internal volume, the bladder having a normal, relaxed state, in which the internal volume is filled with a fluid and a retracted state in which the fluid is evacuated from the internal volume. Two stiffener ribs placed on the inner surface of the bladder, parallel to each other and to the lengthwise axis of the tube at diametrically opposite positions. A plurality of emitters and detectors arranged in a linear array are embedded in one of the ribs, so as to emit and detect light through the bladder. A fluid port extending through the tube and communicating with the internal volume, through which the internal volume can be filled with or emptied of the fluid.

Claims

1. A cuff for measuring physiological parameters of an appendage, including volume or change in volume of the appendage, comprising:

a hollow, rigid tube having an inner surface and opposed ends;

a bladder having an inner surface, an outer surface, and opposed ends, the ends of the bladder being sealed to the ends of the tube to create an enclosed internal volume between the inner surface of the bladder and the inner surface of the tube and an external volume defined by the outer surface of the bladder and surrounded by the internal volume, the bladder having a normal, relaxed state, in which the internal volume is filled with a fluid and a retracted state in which the fluid is evacuated from the internal volume; and

emitter means for emitting at least one wavelength of light and detector means separated from the emitter means by a separation distance for detecting the at least one wavelength of light emitted by the emitter means, the emitter means and the detector means being positioned in the enclosed internal volume for measuring volume or change in volume of the appendage, the number of wavelengths of light emitted by the emitter means being governed by the number of physiological parameters being measured other than volume or change in volume, and the number of detector means being governed by the need for spatial differentiation;

wherein the bladder has a sufficient wall thickness and is made from a material tinted with pigments selected such that the bladder material will absorb the specific wavelengths of light emitted by the emitter means to damp light piping but also allow for sufficient transmission of light through the cuff into and out of the appendage to properly illuminate the tissue and to properly detect the light back-scattered from the appendage.

2. The cuff of claim 1, wherein the bladder is made from a material tinted with pigments selected such that the bladder material also will achieve attenuation such as to decrease the intensity of the piped light to below the governing SNR of the detector means.