Apparatus for detecting blood pressure and electrocardiographic waveforms

Abstract: An apparatus that detects both the blood pressure and the electrocardiographic waveform of a living subject and that can be quickly and easily fitted to the living subject includes a cuff (10) that is wrapped around a portion of the living subject for detecting the subject's blood pressure, and a flexible electrocardio electrode (21) on the inner surface (18) of the cuff for detecting the electrocardiographic waveform generated by the living subject's cardiac muscle. When the cuff is wrapped around a portion of the living subject, the electrocardiographic electrode is automatically fitted and correctly positioned on the living subject. Because the electrocardio electrode does not have to be separately fitted and attached to the living subject, the "set up" time is significantly reduced. Thus, the apparatus of this invention is especially useful in emergency medical situations, where rapid measurements are required.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to blood pressure measuring devices. More specifically, this invention is directed to an apparatus for detecting both the blood pressure and electrocardiographic waveform of a living subject. 2. Description of Related Art The blood pressure of a living subject is typically measured with the use of a cuff that is wrapped around a portion of the living subject. The cuff applies pressure to the living subject and the living subject's blood pressure is measured using a well known oscillometric method, which is based on detecting changes in the amplitude of a synchronous wave pulsation as the pressure applied by the cuff is gradually released. In certain medical situations, it is desirable to obtain both the blood pressure and an electrocardiogram of the living subject. In order to obtain an electrocardiogram, the electrocardiographic waveform, generated as a result of the action potential of the subject's cardiac muscle, must be detected. The electrocardiographic waveform is typically detected with electrocardio electrodes that are attached to the living subject. In order to detect both the electrocardiographic waveform and the blood pressure of the living subject, the cuff for measuring the blood pressure and the electrocardio electrodes for measuring the electrocardiographic waveform must be separately fitted and attached to the living subject. The additional time required to separately attach and fit the cuff and electrocardio electrodes to the living subject may be detrimental to the living subject in situations where a rapid measurement is required, e.g., an emergency medical situation. EP 553 372 A1 discloses a method and system for monitoring vital signs. In particular, a combined system is described for measuring blood pressure and an electrocardiogram by means of a cuff having an electrocardiogram electrode arranged at the inner wall of the cuff. SUMMARY OF THE INVENTION This invention provides an apparatus in accordance with claim 1 that detects both the blood pressure and the electrocardiographic waveform of a living subject and that can be quickly and easily fitted to the living subject. The apparatus comprises a cuff that is wrapped around a portion of the living subject for detecting the subject's blood pressure, and a flexible electrocardio electrode on the inner surface of the cuff for detecting the electrocardiographic waveform generated by the living subject's cardiac muscle. The apparatus of this invention is attached to the living subject by wrapping the cuff around a portion of the living subject. When the cuff is wrapped around a portion of the living subject, the electrocardiographic electrode is automatically fitted and correctly positioned on the living subject. Thus, the living subject's blood pressure and electrocardiographic waveform can be detected simultaneously. Because the electrocardio electrode does not have to be separately fitted and attached to the living subject, the "set up" time is significantly reduced. Thus, the apparatus of this invention is especially useful in emergency medical situations, where rapid measurements are required. In the apparatus according to the invention, the electrocardio electrode comprises a separate piece of conductive fabric that is attached to the inner surface of the cuff with a quick-release attachment mechanism. Thus, the electrocardio electrode can be easily removed and replaced if it becomes inoperative. These and other features and advantages of this invention are described in or are apparent from the following detailed description of the preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS The preferred embodiments of this invention will be described in detail, with reference to the following figures, wherein: Figure 1 and 2 are plan views of the blood pressure/electrocardiographic waveform detecting apparatus of this invention; Figure 3 is a sectional view of the embodiment of Figs. 1 and 2 taken along the section line 7-7 of Fig. 2; and Figure 4 is a schematic diagram of a blood pressure/electrocardiographic waveform measuring system that incorporates the blood pressure/electrocardiographic waveform detecting apparatus of this invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Figures 1-3 illustrate a preferred embodiment of the blood pressure/electrocardiographic waveform detection apparatus of this invention. In this embodiment, the cuff 80 comprises an outer member 82 and an inner member 84. The outer member 82 and the inner member 84 preferably have substantially the same shape, and are preferably joined together along an outer area indicated by the dashed lines 89 and 93. The outer member 82 and the inner member 84 are preferably made of a synthetic resin material, suitably a material made of soft vinyl chloride or nylon, and are preferably joined with an adhesive or by high frequency welding. When the outer member 82 and the inner member 84 are joined along the area indicated by dashed lines 89 and 93, airtight bag portions 88a and 88b are created. In the preferred embodiment, only the airtight bag portion 88a is used to apply pressure to the living subject. At the time the outer member 82 and the inner member 84 are joined, a connection cylinder 86 is preferably positioned between the outer member 82 and the inner member 84. The connection cylinder 86 partially extend into and out of the airtight bag portion 88a. A flexible electrically conductive fabric 90, preferably a non-woven fabric, is attached to the inner member 84 within the boundary of the airtight bag portion 88a. The electrically conductive fabric 90 is suitably a blended yam formed from 35% rayon, 35% polyester and 30% carbon fiber, and is preferably approximately 0.55 millimeters thick with a density of 60 g/m 2 . The electrically conductive fabric 90 is attached to the inner member 84 with a quick-release mechanism, suitably a double-sided adhesive tape 91. The electrically conductive fabric 90 is preferably attached in close proximity to the connection cylinder 86. An inflation tube 94 is attached to connection cylinder 86. A lead wire 92 is disposed inside the inflation tube 94. One end of the lead wire 92 is disposed between the conductive fabric 90 and the inner member 84 to electrically contact the electrically conductive fabric 90. A pair of fasteners 96 and 98 are attached to the outer member 82 and the inner member 84, respectively. The fasteners 96 and 98 are preferably sewed onto the cuff 80. The fasteners 96 and 98 are preferably Velcro™-type fasteners, with one of the fasteners comprising a plurality of hooks made of synthetic resin and the other fastener comprising a plurality of loop-shaped fibers that engage the plurality of hooks when the fasteners 96 and 98 are brought into physical contact. The fasteners 96 and 98 are positioned to come into physical contact when the cuff 80 is wrapped around a portion of a living subject. Figure 4 shows a blood pressure/electrocardiographic waveform measuring system 70 that incorporates the blood pressure/electrocardiographic waveform detecting apparatus of this invention. The cuff 80 is wrapped around the upper arm 68 and is held in place by bringing the two fasteners 96 and 98 into physical contact. The cuff 80 is attached so that the connection cylinder 86 is closest to the elbow. The inflation tube 94, which extends from the connection cylinder 86, is connected to the air pump 74 through the compressed air inflation valve 72. The lead wire 92 is connected to the electrocardiographic device 75. In the embodiment of Figures 1-4, the conductive fabric 90 functions as the electrocardio electrode for detecting the electrocardiographic waveform. Because the conductive fabric 90 is attached with a quick-release mechanism, it can be easily removed and exchanged if it becomes inoperative. While this invention has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. For example, in the embodiment of Figures 1-4, the outer member 82 and the inner member 84 are attached together along substantially their entire perimeters. However, the outer member 82 and the inner member 84 may be only partially attached together. For example, the outer member 82 and the inner member 84 may be attached together only along the area that corresponds to the bag portion 88a, i.e., the area indicated by dashed line 89. Furthermore, in the embodiment described above, the lead wire 92 is disposed inside the inflation tube 94. However, other means of guiding the lead wire from the cuff may be utilized. For example, the lead wire 92 may be wrapped around the inflation tube 94. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative not limiting.

Claims: An apparatus for detecting a blood pressure and an electrocardiographic waveform of a living subject, comprising: a cuff (80) wrapable around a portion of the living subject and having an inner surface (84) and an outer surface (82), the inner surface (84) making physical contact with the living subject when the cuff (80) is wrapped around the portion of the living subject; and an electrode (90) positioned on the inner surface (84) of the cuff (80) for detecting the electrocardiographic waveform of the living subject, characterized in that the electrode (90) comprises an electrically conductive fabric (90) that is attached to the inner surface (84) of the cuff (80) with a quick release mechanism (91). The apparatus of claim 1, wherein the electrically conductive fabric (90) comprises 35% rayon, 35% polyester and 30% carbon fiber. The apparatus of claims 1 or 2, wherein the cuff (80) comprises: an inner member (84); and an outer member (82) attached to the inner member (84) to form an inflatable airtight bag portion (88a, 88b) between the inner member (84) and the outer member (82). The apparatus of claim 3, further comprising: a connection cylinder (86) positioned between the inner member (84) and the outer member (82), the connection cylinder (86) partially extending into and out of the airtight bag portion (88a); a flexible inflation tube (94) connected to the connection cylinder (86); and a wire (92) disposed inside the flexible inflation tube (94) and capable of electrically contacting the electrically conductive fabric (90). The apparatus according to anyone of claims 1 to 4, further comprising: an air pump (74) connected to an inflatable portion (88a) of the cuff (80); and an electrocardiographic device (75) connected to the electrode (90), the electrocardiograhic device (75) capable of processing the electrocardiographic waveform detected by the electrode (90).

Inventors: INUKAI HIDEKATSU, SAKAI HIROSHI, INUKAI, HIDEKATSU, SAKAI, HIROSHI
Applicants: COLIN CORP, COLIN CORPORATION
Application year: 1997
Main classification: A61B5
IPC codes: A61B5