Patent GB-1467344-A (GB)
Title: Life sign monitoring apparatus
IPC: A61B5/274
Filed: 1974-05-08
Abstract: 1467344 Cardiac resuscitator and monitoring apparatus CARDIAC RESUSCITATOR CORP 8 May 1974 20382/74 Heading G1N(E) [Also in Division H4] In a cardiac resuscitator for a patient suffering from a heart attack, means for monitoring electrical activity associated with a patient's heart and means for sensing bodily movement are connected to a logic circuit, which may supply a regular pacing impulse Fig. 12 (not shown) or a defibrillating pulse Fig. 13 (not shown), in dependence upon the sensed electrical activity and movements (Table I) Fig. 6 (not shown).  An oropharyngeal airway 10 of the type used for mouth-to-mouth resuscitation is adapted to carry two opposite, positive and negative, electrodes 1 and 2 and a neutral electrode 3. These electrodes are used with a further separate external electrode 5 (for placing over the heart) to supply signals to the logic circuitry and pulse generators 24, Figs. 6, 7, 12 and 13 (not shown). To indicate body movement, the logic circuitry may also receive a signal from a microphone 22, positioned as shown, also Fig. 10 (not shown) sets out its associated signal processing circuit. The microphone may be separate from the airway 10 and may be placed over the patient's neck near a constricted blood vessel to sense sounds indicating body movement. An associated signal processing circuit is disclosed Fig. 11 (not shown) that provides a signal indicating any movement or a signal corresponding to any pulse rate. Fig. 4 shows an elastic belt 26 for fitting around the patient's chest. The belt is joined by a strain gauge 28 whose electrical output is processed  Figs. 8 or 9 (not shown) to provide an electrical signal indicating any breathing movements. An alternative arrangement Fig. 5 (not shown) consists of a pair of flexible plastic tongs (36), (38) hinged together in a spring-like manner for making firm contact with the patient's chest. The ends of the tongs carry electrodes and the centre hinged portion carries a conductive sponge material whose resistance varies as it becomes compressed during breathing. All the aforementioned electrodes may be used for receiving electrical signals from the body may also be used to apply the signals from the pacemaker circuit Fig. 12 (not shown) and the defibrillating circuit Fig. 13 (not shown). The description discloses block diagrams of a combined signal processing circuit Figs. 14, 15, 16 and 17 (not shown), together with an alternative circuit Fig. 18 (not shown) which uses cathode ray storage tubes for retaining one or more E.C.G. signals or breath sound traces on a cathode ray tube. A block diagram circuit Fig. 20 (not shown) for providing a numerical indication of the pulse rate is disclosed and a mechanical arrangement Fig. 19 (not shown) for recording the E.C.G. signal on a strip of paper is disclosed. As a substitute for the oro-pharyngeal airway of Fig. 1, a plastic inter tracheal tube 270, Fig. 21, may be employed. A helical conducting wire or ribbon 272 embedded in the surface of the tube, extends from an electrode 274 to electrodes 273 and 277 that are mounted on an expandable portion 275. As before a microphone 276 may be attached. Electrodes in the form of conducting wires 294, Fig. 22, or nasal tubes 290, 292 provide another means of receiving/or applying electrical signals. The nasal tubes may be connected via flexible tubes 282, 284 to a connector 288 for supplying oxygen. As well as serving its normal function a catheter may be converted to become an electrode by winding wire helically on the outside of the catheter. If the patient is conscious, the airway tubes, Figs. 1 and 21 are not practical so the description discloses three types of spring clip electrodes Figs. 24, 25 and 26, Figs. 24 and 25 (not shown), that are intended to be clamped on to the lip or cheek of the patient, to contact the inside and the outside of the mouth. The spring clip electrode may also carry a microphone. Stainless spring steel rings Figs. 27 and 28, Fig. 27 (not shown) may be used as electrodes that are fitted on the fingers of the patient. The ring is normally carried in the distended condition Fig. 27 (not shown), with a ball 342 on one end. After it is placed on the patient's finger, the ball is sprung out of its socket causing the ring to grasp the finger. A similar large wrist bracelet arrangement Figs. 29 and 30 (not shown) but made out of mallable metal is disclosed. The bracelet carries a sponge containing an electrolyte on its inside. The description mentions using temperature sensitive devices to detect body movement.