Dual bag blood pressure cuff

[57] ABSTRACT

An inflatable cuff for deriving blood pressure data by uniform vessel occlusion in all shape limbs to provide accurate compression comprising first and second inflatable bags positioned lengthwise in the cuff and in an overlying relationship within the cuff, the second bag being smaller than the first in its width dimension and distally positioned on the cuff, and the first and second bags connected so as to initially supply the second bag with a greater air pressure than that supplied to the first bag to anchor the cuff to the subject’s extremity and generate a uniform pressure compression pattern along the extremity length under the cuff.

Claims, 2 Drawing Figures

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PATENTED AUG 141973

3,752,148

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3,752,148

DUAL BAG BLOOD PRESSURE CUFF

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an improved inflatable blood pressure cuff for use with sphygmomanometers or similar equipment for deriving a patient’s blood pressure data.

2. Description of the Prior Art

As is well known, measurements of arterial blood pressure are commonly obtained by use of sphygmomanometers including a pneumatic cuff encircling a patient’s extremity, normally the arm, which have become standard instruments. For the most part, commercially available pneumatic cuffs have been found to work well on the upper extremities.

Major problems, however, have been incurred in those instances where the cross-section of the extremity varies significantly along short distances of the extremity length, such as commonly occurs at a patient’s thigh. Normally, with the standard cylindrical bag used on an irregular shaped or tapered leg where a crosssection along the extremity length varies significantly, there is experienced a slipping of the cuff when the bag is being inflated. In addition, in utilizing a transducer under the cuff, when applied to the thigh for detecting Korotkoff sounds, arterial wall motion, or blood flow, problems are incurred due to the cuff inability to generate the uniform pressure compression pattern on the arteries, which results in poor contact between the transducer and the leg. We have found that inaccurate data is derived as a consequence of these problems, to the extent that as a whole, such an approach is frequently unreliable.

SUMMARY

The purpose of the present invention is to obviate the problems of the type enumerated above. This is accomplished by provision of a cuff comprising a dual inflatable bag overlapping configuration where the second smaller bag is distally placed under the first bag as applied to a patient, whereby in operation of the cuff, the first bag is filled first to, in effect, anchor the cuff to the leg. After the first bag is partially filled the second begins to fill through a tube connection between the two bags, until both are brought to the desired pressure at which time the filling is terminated. Such an arrangement not only prevents slippage, but additionally allows for generation of uniform pressure compresssion pattern and better couples a transducer to the leg which transducer is positioned under the cuff. The latter improvement provides for a better transfer of energy to and/or from the artery area being constricted by the cuff.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a preferred form of the present invention.

FIG. 2 is a perspective view of a section of the cuff containing the dual bag configuration.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the drawings there is shown in FIG. 1 a cloth cuff generally referred to as 11, having a first compartment for containing a first bladder or bag 12, and a second compartment for containing a second bladder or bag 13. As is illustrated, the larger bag 12 virtually extends across the entire width of the cloth cuff 11. The small bag 13, on the other hand, is positioned, in its own compartment underneath the larger bag so as to be centered lengthwise with the larger bag. Widthwise, however, the small bag 13 is positioned with one edge substantially aligned with one edge of the large bag 13.

Suitable apertures are provided in the bags 12,13 for an inlet-outlet air tube 14 which is coupled to the smaller bag 13 and for a connector tube 15 coupling small bag 13 with larger bag 12, the latter having a supplemental outlet air tube 16 coupled therefrom. The edge of the large bag 12, along which an edge of the small bag 13 is aligned, would be the distal edge of the cuff when applied about the patient’s thigh or other extremity. In the preferred embodiment, the length of the smaller bag may be anywhere from 60 to 80 percent of the large bag length and roughly anywhere from 47 to 67 percent of the large bag width.

IF desired, an affixing unit 17 which might comprise of a pocket, Velcro member or other suitable receiving member, could be employed at the surface of the samll bag 13 to secure a transducer member utilized with the cuff such as, for example, a microphone, piezoelectric crystal for ultrasonic application, strain-gauge member, etc., through which transducer suitable signals could be derived for acquiring blood pressure or blood flow data.

In operation, cuff 11 is applied around an extremity such as a thigh so that the small bag 13 is distally positioned. Air pressure is then applied from a suitable manual or automatic source through the tube 14 to the first or small bag 13 which fills to anchor the cuff 11 to the extremity thereby holding the cuff firmly in place. After the small bag is filled, the large bag 12 which placed in series with small bag 13, is filled by air passing through the connecting tubing 15, the connecting tubing serving as a tubing resistor.

Air continues to flow until both bags 12 and 13 are brought to the desired pressure at which time the filling is terminated, the pressure in each bag being the same. This balancing of pressures in the cuff with the configuration of the two-bag arrangement, maintains a pressure profile in the thigh which is constant along the length of the cuff so as to maintain a uniform pressure compression pattern for compression of the arteries of the leg and simultaneously maintains the transducer employed in firm engagement with the leg surface.

The second stage of process, of course, is the emptying phase where air is exhausted to the atmosphere back through the tube 14. Because of its much larger size, the large bag empties into the small bag at a rate to maintain the pressure in the small bag almost equal to itself as the bag is being exhausted to the atmosphere allowing the small bag to maintain the cuff anchored to the extremity and insure optimun pressure distribution at this critical stage in which blood pressure data is being collected, such data being essential for diagnostic purposes. If it is desired to empty the large bag at a more rapid rate, this can be accomplished by a simple valve adjustment of the supplemental outlet tube 16 which is otherwise in a mormally closed condition.