APPARATUS AND SYSTEM FOR MONITORING

Abstract

A monitoring device wearable by a person to be monitored, comprising: one or more sensing means for sensing cardio, respiratory, physiological and/or other information from the person; processing means for analysing the sensed information; memory means for storing the sensed and/or analysed information; and communication means for transmitting at least the analysed information. At least one waveform acquired from the sensed cardio, respiratory, physiological and/or other information is digitised in real time; analysis of the sensed and/or digitised information is performed in real-time and a welfare indication of the person computed in real-time; and the computed welfare indication of the person is transmitted by the communication means and/or stored in the memory means.

Claims

1-134. (canceled)

135. A monitoring device wearable by a person to be monitored, comprising: one or more sensing means for sensing cardio, respiratory, physiological and/or other information from the person; processing means for analysing the sensed information and capable of processing the (primary) cardio, respiratory, physiological and/or other information to derive secondary cardio, respiratory, physiological and/or other information; memory means for storing the sensed and/or analysed information; and communication means for transmitting at least a portion of the analysed information, wherein: at least one waveform acquired from the sensed cardio, respiratory, physiological and/or other information is digitised in real-time; analysis of the sensed and/or digitised information is performed in real-time and a welfare indication of the person computed in real-time; and the computed welfare indication of the person is transmitted by the communication means and/or stored in the memory means, the welfare indication is determinable by analysis and/or comparison of at least two forms of information selected from the primary and/or secondary cardio, respiratory, physiological and/or other information, with thresholds from configurable data stored in the memory, wherein the thresholds and configurable data are modifiable for a type or range of activities or environments.

136. A monitoring device as claimed in claim 135, wherein the one or more sensing means comprises at least two sensing means.

137. A monitoring device as claimed in claim 135, wherein the processor is capable of processing at least two forms of information selected from cardio, respiratory, physiological and/or other information, to derive data relating to a welfare indication of a wearer.

138. A monitoring device as claimed in claim 135, wherein the monitoring device is capable of detecting cardio, respiratory, physiological and/or other information relating to one or more of the following: a) an electrical view of the heart of a person; b) the respiration effort of a person; c) the blood oxygen level of a person; d) the skin surface impedance of a person; e) whether there is correct skin electrode and person contact; f) the skin surface temperature of a person; g) whether a specific activity is being undertaken by a person; h) whether a person has been effected by an impact; i) the body orientation of a person; j) the movement of a person; k) the level of ambulation of a person; l) the absence of expected data; m) the cognitive state of a person; n) a person's own assessment of welfare; and/or o) whether excessive gravitational forces are being exerted on a person.

139. A monitoring device as claimed in claim 135, wherein the thresholds and configurable data are automatically, manually or remotely modifiable or learned for a specific person, or derivable from previous analysis, and/or comparison of cardio, respiratory, physiological and/or other information and the thresholds.

140. A monitoring device as claimed in claim 135, wherein the thresholds and configurable data are modifiable as a result of contextual information relating to a person, wherein the contextual information relates to one or more of the following: a) whether a person is moving; b) whether a person has been effected by an impact; c) whether a person is carrying out a specific activity; d) the current or recent level of ambulation or activity levels of a person; e) environmental factors experienced a person; or f) the cognitive state of a person, wherein the environmental factors include: i) ambient temperature; ii) ambient pressure; iii) altitude; iv) humidity; or v) relative motion of the person.

141. A monitoring device as claimed in claim 135, capable of providing the configurable data from analysis of time-thresholds which conditions must be measured before a transition in the welfare indication occurs for one or more of the following conditions: a) high, low or intermediate signal rates; b) an absence of measurable signal rates; c) the rate of change of an averaged signal rate; d) averages of a measured signal rate; e) the short-term average of a measured signal rate; f) the long-term average of a measured data signal rate; e) the normal or abnormal characteristics of a waveform; f) intermediate average of a measured signal rate; or g) the time-threshold periods for transitions and/or average windows.

142. A monitoring device as claimed in claim 135, wherein the welfare indication is capable of being overridden or reduced in severity by additional contextual information experienced by a person.

143. A monitoring device as claimed in claim 135, wherein the sensitivity of detection is modifiable in response to the activity status, level of ambulation and/or body position detected by the monitoring device, and/or contextual information experienced by a person.

144. A monitoring device as claimed in claim 135, capable of comparing more than one measurement of cardio information to provide a cardio confidence score and/or capable of comparing more than measurement of respiratory information to provide a respiratory confidence score.

145. A monitoring device as claimed in claim 144, capable of analysing the cardio confidence score and the respiratory confidence score, together with data relating to the individual signal quality or contextual information to provide an overall confidence score.

146. A monitoring device as claimed in claim 135, wherein the welfare indication comprises a state of: absence or substantial absence of vital signs, following an absence of vital signs over a time threshold.

147. A monitoring device as claimed in claim 135, wherein the monitoring device is capable of modifying the severity of its welfare indication and the time threshold for indicating the welfare indication following detection of the absence, or substantial absence, of one or more cardio or respiratory measures.

148. A monitoring device as claimed in claim 135, wherein, when a person has initially a normal welfare indication or a low-level abnormal welfare indication, a second cardio and/or respiratory measurement is triggerable automatically following determination of an abnormal welfare indication or progressively abnormal welfare indication.

149. A monitoring device as claimed in claim 135, wherein a secondary welfare indication is provided by analysis of thermal and/or neurological information.

150. A monitoring device as claimed in claim 149, wherein a cognitive state of a person is manually determinable by a monitoring station requesting the wearer to carry out an action.

151. A monitoring device as claimed in claim 149, wherein a/the cognitive state of a wearer is automatically determinable following: a variable or set time period; an abnormal welfare indication; or evidence of excessive g-shock to a person, by the person being automatically requested to carry out an action by visual, audible, vibrational or other sensory means.

152. A monitoring device as claimed in claim 150, wherein an abnormal welfare indication is cancellable or movable towards normal, or a worsening of his/her welfare can be indicated, by a person responding to the request to carry out the action.

153. A monitoring device as claimed in claim 135, wherein the monitoring device is capable of abbreviated disclosure, when only a subset of the information is communicated to the monitoring station, or full-disclosure, when all digitised information, or some or all of the waveforms of the cardio, respiratory, physiological and/or other information, is communicated to the monitoring station.

154. A monitoring device as claimed in claim 153, wherein full-disclosure can be activated automatically by determination of an abnormal welfare indication, or is manually-activatable by a person or by the monitoring station.

155. A monitoring device as claimed in claim 153, wherein the subset comprises one or more of: a) primary and/or secondary welfare indication; b) heart and/or respiration rate; c) skin temperature; d) motion and/or activity level; e) body orientation; f) user identification information; g) unit identification information; h) unit self-check diagnostics; and/or i) confidence scores.

156. A monitoring device as claimed in claim 135, further comprising a request and response device, wearable by a person, for communication with the monitoring device and/or the monitoring station.

157. A monitoring device as claimed in claim 135, wherein assessment of a person's welfare is optimised by transmittal and storage of wearer-personalisation information, environment information and/or activity information by the monitoring station, any intermediate equipment and/or the monitoring device.

158. A monitoring device as claimed in claim 135, further comprising connectable external sensors for detection of further cardio, respiratory, physiological and/or other information.

159. A monitoring device as claimed in claim 135, capable of detecting the presence of motion of a person and using the evidence of motion to reduce the bandwidth of the cardio signal receiver to improve the signal to noise ratio and improve performance, and/or the monitoring device is capable of detecting the presence of motion and body position of a person and using evidence of motion and body position to modify the signal gain, bandwidth and sensitivity of the respiratory signal receiver to improve performance.

160. A monitoring device wearable by a person to be monitored, comprising: a detachable anatomically-shaped sensor electronics module comprising processing means, memory means and communications means; and a connector, harness and/or other support wearable by a person, capable of attaching, or holding in sensory/sensing proximity, the sensor electronics module to a person, and comprising one or more sensing means, wherein the monitoring device: senses cardio, respiratory, physiological and/or other information from a person; and performs real-time analysis of the sensed information and computes a real-time welfare indication of the person for onwards transmission/communication.

161. A monitoring device as claimed in claim 160, wherein the one or more sensing means comprise at least two sensing means.

162. A monitoring device as claimed in claim 160, the monitoring device comprises means for detecting skin temperature, wherein the means for detecting is a thermistor.

163. A monitoring device as claimed in claim 160, the monitoring device comprises means for detection of motion, body position and/or impact, wherein the means for detection is an accelerometer.

164. A monitoring device as claimed in claim 160, wherein the monitoring device further comprises a chest-expansion sensor, wherein the sensor is a variable strain sensor.

165. A monitoring device as claimed in claim 160, wherein the monitoring device comprises means for detecting blood oxygen levels of a user, wherein the means is a reflectance-type sensor for pulse oximetry analysis.

166. A monitoring device as claimed in claim 160, wherein the sensor electronics module is capable of measuring, processing, analysing and/or onwards transmission of information relating to one or more of the following: a) an electrical view of the heart of a person; b) the respiration effort of a person; c) the blood oxygen level of a person; d) the skin surface impedance of a person; e) whether there is correct skin electrode and person contact; f) the skin surface temperature of a person; g) whether a specific activity is being undertaken by a person; h) whether a person has been effected by an impact; i) the body orientation of a person; j) the movement of a person; k) the level of ambulation of a person; l) the absence of expected data; m) the cognitive state of a person; n) a person's own assessment of welfare; and/or o) whether excessive gravitational forces are being exerted on a person.

167. A monitoring device as claimed in claim 160, wherein the sensor electronics module is anatomically-shaped to fit the thoracic region, or in the region of the sternum and upper abdomen, of a person.

168. A monitoring device as claimed in claim 160, wherein the wearable monitoring device comprises three skin electrodes.

169. A monitoring device as claimed in claim 160, wherein the connector harness and/or other support comprises one or more of the following: a) an adhesive pad; b) a yolk; c) an item of clothing; or d) standard electrocardiograph adhesive skin electrodes.

170. A monitoring device as claimed in claim 169, wherein the adhesive pad is anatomically-shaped to fit the thoracic region, or in the region of the sternum and upper abdomen, of a person.

171. A monitoring device as claimed in claim 160, wherein the sensor electronic module comprises an electrical interconnect which enables connection of one or more of the following: wired computing terminals; auxiliary sensors; an auxiliary pulse oximetry module; and/or a power source, or a data link for connection of: auxiliary sensors; monitoring equipment; transmission equipment; or any auxiliary electrical equipment, in the form of a request and response device.

172. A monitoring system for monitoring of one or more persons comprising: a monitoring device as claimed in claim 135, wearable by the or each person being monitored; and one or more monitoring stations, wherein: the or each monitoring device is in communication with the one or more monitoring stations; and the one or more monitoring stations receive and monitor the computed welfare indication from the or each monitoring device to assess the wellbeing of each person being monitored.

173. A monitoring system as claimed in claim 172, wherein configurable parameters may be determined, and adjusted, recorded and stored within the monitoring device whilst in a ‘training mode’, for use when the monitoring device is not in a training mode.

174. A monitoring system for monitoring of one or more persons comprising: a monitoring device as claimed in claim 160, wearable by the or each person being monitored; and one or more monitoring stations, wherein: the or each monitoring device is in communication with the one or more monitoring stations; and the one or more monitoring stations receive and monitor the computed welfare indication from the or each monitoring device to assess the wellbeing of each person being monitored.

175. A monitoring system as claimed in claim 174, wherein configurable parameters may be determined, and adjusted, recorded and stored within the monitoring device whilst in a ‘training mode’, for use when the monitoring device is not in a training mode.

176. A monitoring device wearable by a person to be monitored, comprising: one or more sensing means for sensing cardio, respiratory, physiological and/or other information from the person; processing means for analysing the sensed information and capable of processing the (primary) cardio, respiratory, physiological and/or other information to derive secondary cardio, respiratory, physiological and/or other information; memory means for storing the sensed and/or analysed information; and communication means for transmitting at least a portion of the analysed information, wherein: at least one waveform acquired from the sensed cardio, respiratory, physiological and/or other information is digitised in real-time; analysis of the sensed and/or digitised information is performed in real-time and a welfare indication of the person computed in real-time; and the computed welfare indication of the person is transmitted by the communication means and/or stored in the memory means, the welfare indication is determinable by analysis and/or comparison of at least two forms of information selected from the primary and/or secondary cardio, respiratory, physiological and/or other information, with thresholds from configurable data stored in the memory, wherein the thresholds and configurable data are modifiable for a type or range of activities or environments, and the thresholds and configurable data are automatically, manually or remotely modifiable or learned for a specific person, or derivable from previous analysis, and/or comparison of cardio, respiratory, physiological and/or other information and the thresholds.

177. A monitoring device wearable by a person to be monitored, comprising: one or more sensing means for sensing cardio, respiratory, physiological and/or other information from the person; processing means for analysing the sensed information and capable of processing the (primary) cardio, respiratory, physiological and/or other information to derive secondary cardio, respiratory, physiological and/or other information; memory means for storing the sensed and/or analysed information; and communication means for transmitting at least a portion of the analysed information, wherein: at least one waveform acquired from the sensed cardio, respiratory, physiological and/or other information is digitised in real-time; analysis of the sensed and/or digitised information is performed in real-time and a welfare indication of the person computed in real-time; and the computed welfare indication of the person is transmitted by the communication means and/or stored in the memory means, the welfare indication is determinable by analysis and/or comparison of at least two forms of information selected from the primary and/or secondary cardio, respiratory, physiological and/or other information, with thresholds from configurable data stored in the memory, and the thresholds and configurable data are modifiable for a type or range of activities or environments, wherein the sensitivity of detection is modifiable in response to the activity status, level of ambulation and/or body position detected by the monitoring device, and/or contextual information experienced by a person.

178. A monitoring device wearable by a person to be monitored, comprising: a detachable anatomically-shaped sensor electronics module comprising processing means, memory means and communications means; and a connector, harness and/or other support wearable by a person, capable of attaching, or holding in sensory/sensing proximity, the sensor electronics module to a person, and comprising one or more sensing means, wherein the monitoring device: senses cardio, respiratory, physiological and/or other information from a person; and performs real-time analysis of the sensed information and computes a real-time welfare indication of the person for onwards transmission/communication, wherein the monitoring device comprises means for detecting blood oxygen levels of a user.

Description

[0274] In order that the invention can be fully disclosed, embodiments of the invention are described, by way of example only, with reference to the accompanying drawings, in which:

[0275] FIG. 1 is a diagram showing a monitoring a system according to the present invention;

[0276] FIG. 2a is a front view of a person, showing approximate location of a sensing means according to the present invention;

[0277] FIG. 2b is a back view of a person of FIG. 2a;

[0278] FIG. 3a is a front view of a person, showing location of a sensor electronics module and connector (yolk) according to the present invention;

[0279] FIG. 3b is a back view of a person of FIG. 3a;

[0280] FIG. 4 is a view of the sensor electronics module and connector of FIGS. 3a and 3b, showing the manner of connection therebetween;

[0281] FIG. 5 is a view of the plate of the connector of FIGS. 3a and 3b, showing the location of electrical and physical connectors on a strap-based harness;

[0282] FIG. 6 is an adhesive connection assembly according to the present invention, showing the location of electrical and physical connectors on the adhesive pad;

[0283] FIGS. 7a and 7b are views of items of clothing incorporating a sensor electronics module according to the present invention;

[0284] FIG. 8 is a view of a sensor electronics module according to the present invention, as used by a healthcare practitioner or paramedic;

[0285] FIG. 9 is a block diagram showing the operation of a monitoring device according to the present invention;

[0286] FIG. 10 is a block diagram showing a state transition diagram of the monitoring device according to the present invention for a welfare indication derived from cardio, respiratory, physiological and/or other information (primary welfare indication); and

[0287] FIG. 11 is a block diagram showing a state transition diagram of the monitoring device according to the present invention for neurological response and thermal welfare indication (secondary welfare indication).

[0288] A monitoring system of the present invention is shown in FIG. 1, in particular. A person or user wears a monitoring unit, the person and/or unit indicated generally by reference 1, which records multiple physiological signals from the user 1 and processes them in order to determine a welfare status (welfare indication). The user monitoring unit 1 communicates to a mobile radio terminal 2 via a communication link 3, in order to send data to, and receive data from the mobile radio terminal 2, which in turn communicates, via a communication link 4, to an infrastructure 4,5,6 to which a remote monitoring station 7 is connected. This provides remote access to a user to information from the user monitoring unit 1. The communication system may be, for example, a land-based mobile communications system, such as, a GSM mobile cellular network—which is shown by reference 6. Those skilled in the art will be aware that alternate networks, both terrestrial 6 and/or satellite 5, based may be used to transport the data to and from the remote user, at the monitoring station 7, and that the remote user may be, additionally, not in direct connection with the mobile communications network. In addition, a local monitoring station 8 may be used to communicate with the monitoring unit 1 directly, either by wired or wireless means. In a preferred embodiment, the local monitoring station 8 may be a hand-held computer 8, such as a Pocket PC.

[0289] FIGS. 2a and 2b show respective front and back views of a user. The signals of interest may be derived from an approximately horizontal set of electrodes applied to the central thoracic cavity.

[0290] By the use of differential electrical amplification, the heart's electrical activity can be measured between electrode positions 11 and 12, 11 and 13, and 13 and 12. Those skilled in the art will be aware that, whilst the electrode spacing is small, for example 10 cm, the proximity of the sensor to the heart will compensate to allow a reasonable signal to noise ratio to be achieved. Respiration effort may be measured across electrodes 11 and 12, or 11 and 13 simultaneously, by presenting a high frequency AC signal from a constant current source, such that variation in the impedance of the diaphragm, owing to respiration, will result in a voltage waveform which approximates to respiration effort. This signal may be used to derive respiration rate after appropriate filtering. The same technique can also be used to determine the impedance of the electrode 11, 12, 13 connection to the skin and to flag a “lead-off” condition if they exceed a certain threshold.

[0291] Those skilled in the art will also be aware that blood oxygen percentage level (SpO.sub.2) and pulsatile waveform can also be measured using the established technique of pulse oximetry, and a reflectance-type sensor placed can be placed on the sternum bone within the same approximate area, as indicated by reference 10. The use of this sensor 10 may be optional depending on the user's requirements.

[0292] Skin surface temperature may be measured from a site close to reference 15, which is preferred because of its proximity to the user's liver.

[0293] Respiration effort may also be measured by the measurement of the rib cage expansion and contraction measured around some or all of the circumference of the thorax, as denoted by the dotted line referenced as 14. Those skilled in the art will know this measurement location to be consistent with a body function known as the ‘zyphoid process’, which can be used to derive respiration effort.

[0294] FIGS. 3a and 3b show the respective front and back of a user. The monitoring device electronics is housed in a unit 28 (sensor electronics module [SEM] 28) which is attached to a sensor connection harness 21. The sensor connection harness 20,21 contains within it, the necessary skin-contacting electrodes 23,24,25. These electrodes 23,24,25 can be made from silver coated fabric or a silver-loaded, silicon elastomeric block—as shown at reference 26. The harness 20,21 is held to the body firmly by an elastic waistband 21, which also contains a resistive (or variable) strain sensor 22—which resistance changes with chest expansion. The horizontal band 21 is held in place by an over the shoulder strap 20, to reduce the chance of the harness 20,21 slipping down the torso during exercise. The tension on the horizontal strap 21 may be adjusted using an adjuster strap 27. The non-skin contacting side of the harness may be finished with a decorative fabric cover to protect the sensors within the strap. The harness 20,21 may be produced in varying sizes, for example small, medium and large, so as to cope with size variations of users. In addition, in the region of point indicated by reference 29, at which the strap 20 attaches to the central point 25, an aperture may be provided to place the reflectance pulse oximetry sensor in position above the sternum.

[0295] With reference to FIG. 4, the SEM 30 is electrically and mechanically connected to a sensor connection assembly 42, which is secured to the body of a user using a strap-based harness 35. The sensor connection assembly 42 has a central mounting point (mounting plate) 40 made from, for example, a suitable non-conductive body-conformal material, for example, polycarbonate. The central mounting point 40 is attached, for example, by means of clothing stitching, to semi-flexible straps 35, which are passed around the body to secure the connection assembly 42 in place and hold the assembly 42 to the body with a degree on tension such that unwanted movement of the assembly is minimised. The SEM 30 is housed in a suitable plastic environmentally sealed enclosure 30 and can be designed to be compact, for example, around 73 mm high by 123 mm wide by 16 mm thick. The SEM 30 comprises an upper case 31 and lower case 32, which may be separated in order to fit the electronics hardware inside, as part of the manufacture of the SEM 30. The rear (or body-side) of the case also contains a skin probe 39 to contact the user's skin, in order to measure temperature. Electrical and mechanical connection is achieved using electrically conductive male snap-rivets 41 (for example Micron E391282-085 and E311-a2cl). The SEM 30 contains the matching female snap-fixings 33, allowing the module to be connected to the central mounting point by pressing the two parts together. An advantage of these snap-connections is that the unit may be separated with moderate hand pressure and, hence, can be done by the user when needed. Additionally, the SEM 30 provides an extra electrical interconnect interface 38 to allow charging of its internal battery, wired transfer of data, and connection to the pulse oximetry sensor. When not required, a moulded plastic bung (38) can be used to seal the connector interface.

[0296] FIG. 5 shows the body-facing side of the central mounting point 50,57 of the sensor connection assembly 42, showing part of an over the shoulder strap 52. The snap rivets 55 pass through the mounting point and allow electrical connection to the front electrodes 50,51. The third electrode and respiration band are connected by remote connection means 58. Those skilled in the art will be aware that this can be achieved by a number of means including, for example, flexible wires or flexible conductive printed circuit boards. The reflectance pulse oximetry sensor 53 is optionally held within the assembly 42 with an aperture to allow the sensor head to protrude and contact the body. It is electrically connected by wire to the SEM 30, the positioning of which is shown by the dotted line referenced as 54. Further electrical connectors are shown by references 59 and 60. Further, a protective, waterproof fabric layer 56 may be overlaid on the central mounting point 50 to cover the electrical connections and protect them from damage.

[0297] FIG. 6 shows an adhesive sensor connection assembly 70. The use of an adhesive connection assembly is an alternative to the strap-based harness, discussed above. The assembly comprises a sculpted adhesive membrane 72 (for example the Intellicoat 5230 range) to hold the sensor to the skin of a user. The three electrodes 73,74 and 75 are provided by a circular hydrogel disk (for example Ludlow RG63B) of which one side contacts the skin and the other side is a flexible polyester membrane 76, printed with conductive silver/silver chloride ink tracks 77 for connecting between the electrode points 78 and the snap rivets 79, which are arranged in the same locations as used in the earlier strap harness example. 71 is a release liner material (e.g. Flexcon 94PRTPFW) used to protect the adhesive membrane before application to the body.

[0298] Those skilled in the art will also be aware that alternative electrode assemblies are commonly provided with conductive snap fittings, for example, Ambu® BlueSensor L, and that these could also be used with the present invention.

[0299] FIGS. 7a and 7b show further alternative ways of attaching the monitoring device to a user and show, in particular, how the monitoring device can be incorporated into a user's apparel, either as part of a male-user's vest 82 or as part of a female-user's vest 83. The vests 82,83 may be constructed from a suitable fabric, such a Lycra™, and have sewn internal to the vest electrodes of the style discussed earlier, such that it connects to the SEM 80, via the same conductive snap-rivet method discussed above. The vests 82,83 can also have integrated into them a flexible semi-conductive strap 81, as discussed earlier, to detect a user's respiratory chest movement.

[0300] FIG. 8 shows diagrammatically how the monitoring device 94 can be remotely mounted from the user by a paramedic or healthcare practitioner. Commonly used ECG electrodes 91, 90 and 92 are used to connect to the users skin and, thus, to provide, through wires 93, an ECG signal view, as desired by the medic. For example, the configuration in FIG. 8 provides an ECG view those skilled in the art will recognise as Lead I between 90 and 91 and Lead II between 91 and 92. Such conventional ECG views may offer an advantage of familiarity to a medic. Respiratory effort may also be measured between 91 and 92. The electrodes 90,91,92 connect to the SEM 94 by a special remote sensor connection device which has a connection plate comprising a plastic carrier and aforementioned conductive snap rivets connecting to flying electrode wires 93, with a suitable termination to connect to the electrodes 90,91,92. Additionally, the device contains a wired connection to a pulse oximeter device 95, for example, the NONIN XPOD, which provides a variety of sensor clip assemblies 96 to connect to the users body, for example, a finger, toe or ear clip. In this configuration, the medic may observe the sensor output by means of a portable computing device 97, for example an IPAQ, communicating to the sensor electronics module by wire or wireless means (for example Bluetooth™).

[0301] Referring to FIG. 9, a preferred embodiment of the monitoring device of the present invention may be achieved as follows. ECG measurements are taken from the subject from electrodes sensors attached to the skin and connected to the electronics via connections 100. Considering a single channel of ECG, the ECG signal between two electrodes may be differentially amplified by an amplifier and filter stage contained in the signal conditioning circuit 115, greatly reducing the effect of noise, particularly mains electrical hum. After amplification, the ECG signal is filtered using a band pass filter to select only those frequencies of interest. This is followed by further amplification and low-pass filtering before presentation of the signal to an analog to digital converter (A/D) input of the microprocessor unit 104, which may be an embedded microcontroller such as a Philips 80051. Additional noise immunity may be provided by, for example, reducing the ECG bandwidth to, for example, 5 Hz to 50 Hz, when a user is moving and this may be controlled by the microcontroller, which is able to detect the presence of motion via the accelerometer 102. The additional ECG2 and ECG3 channels would be provided using the same methodology. One or more of the channels contained with the signal conditioning 115 can be have power switched to it by the microcontroller 104 in order to minimise power consumption when the additional signal is unnecessary. Once digitised the microcontroller 104 can performs additional filtering and thresholding specifically designed to detect the presence of the characteristics of an ECG waveform and from this data additional measures, such as ECG heart rate, by counting the number of ECG pulses seen in a window. A signal quality measure can be provided by the microcontroller 104 by measuring the signal to noise ratio of the ECG waveform. Those skilled in the art will recognise several methods exist to undertake this computation within a microcontroller 104. Additionally, the same characteristics may be detected by a hardware circuit contained in 115, which is tuned to notch out the central energy contained in the ECG waveform. Those skilled in the art will recognise this as an R-wave detector. Such circuits have an advantage over the full-ECG derived method described earlier as they reduce power consumption, as the microcontroller receives only a single logic pulse per heart beat and has to undertake less computation. The circuits have a disadvantage in that they are less sensitive to extreme low heart rates and do not adapt as well to a users specific ECG characteristics. Hence, R-wave analysis is also incorporated within the module to provide an alternate heart rate (HRr) and is used preferably when the user's physiology is well within normal expected values. A measure of signal quality can be derived from the R-wave pulse rate signal by measuring its periodicity which should be nominally regular. An overall confidence can then be derived, for example, a figure between 1 and 100, by the mathematical combination of the signal qualities and level of agreement of the two sensed heart rates. Those skilled in the art will recognise that several statistical and mathematical techniques exist to undertake such a computation. A chest expansion sensor is used to provide a primary method of measuring respiration effort (BRb). The sensor 101 is physically attached to the subject as part of the harness or assembly, and electrically connected as part of an impedance measurement network, with its centre point fed into an amplification stage 115 and a band pass filter. Further, amplification may be provided and low-pass filtering can be applied before presentation of the signal to an A/D input of the microprocessor unit 104. The level of gain may be dynamically switched by a logic line from the microcontroller 104 into the signal conditioning section and this may be set depending on the peak to valley levels measured by the microcontroller 104 or on other criteria such as body position. Once digitised by the microcontroller 104, it may deduce a rate by measuring peaks and troughs which will occur in relation to the breathing process. A signal quality indication can be derived from a combination of the symmetry of the breath peaks and troughs, the area of the breathing peak and the number of believed false breathing peaks detected. Respiration measurements may also be derived from the ECG signal. It is well-known in the art that, in a normal subject, the amplitude characteristic of the ECG signal varies over time, and this variation is associated with the respiration effort rate. The microcontroller contains an algorithm which measures this variation and then uses the derived signals to detect breathing peaks and troughs. A third method to measure breathing rate is also employed which is impedance respiration effort, which is measured using a known technique called impedance thoracic pneumography. This is measured using a simple current source amplifier to drive an impedance signal to two of the ECG electrodes 100. The frequency of the current source amplifier output could be in the range of 50-150 kHz. The impedance of the thoracic cavity will vary as the signal passes through it and the wearer breaths in and out. This variation will induce an amplitude change known as amplitude modulation to the constant current signal. The same electrodes (100) can be used to sense this voltage using a differential amplification stage contained in 115 and, after band-pass filtering a simple diode detector followed by further amplification and low-pass filtering, it can then be presented to an A/D input of the microprocessor unit 104. Breathing frequency detection can then be performed as discussed earlier. An overall confidence can also be derived by the microcontroller using similar techniques to those discussed for the heart rate. The preferred embodiment has provision for an accelerometer 102, which is assumed to be two orthogonally mounted two-axis devices, for example the Analog Devices AD XL202E, but may also be a single three axis device. These devices provide the microcontroller 104, via an A to D port with a waveform indicating the g-force applied to the sensor. Thus, by suitable software processing, a body orientation may be deduced by the relative positions of each axes value and also activity and ambulation detected by the frequency and depth of the short term variation in each axes. In addition, high g-load may be measured by monitoring the short term peak value of the accelerometers output and, above a certain level, this signal can be used to assist the computation of welfare indication. Skin temperature is shown being measured by a simple thermistor 103, the output of which is amplified before being presented to an A/D input of the microprocessor unit 104. It will be clear to those skilled in the art that other methods of deriving the physiological parameters would be possible, and that other parameters could also be measured using well-known techniques. The monitoring device contains an alerting device 108 (request and response device 108) which can provide a vibrating sensation to the user in order to trigger a response from the user. Such devices are commonly used in mobile handsets to provide a covert alert and this may be advantageous in certain circumstances. Those skilled in the art will be aware that an audible or visual alert may also be easily incorporated into the sensor. A user's response can be measured by the operation of a button on the SEM or by asking the user to strike the SEM (monitoring device) and detecting the blow using accelerometers sensors contained within the SEM. The circuits described are powered by a cell or cells 106 which may be either primary (for example Alkaline LR03 cells) or secondary rechargeable (for example Varta LIP 553048), which may be regulated to provide a stable and controlled voltage to the circuit elements. After digitising information presented to it, the microcontroller 104 processes the signals further and may undertake further signal conditioning, filtering and numerical computation, in order to derive secondary measures from the signals, such as, rates. The device then uses this data to compute the welfare indication. The monitoring device sends the required data either to an rf transmitter 105, which may be, for example, a wireless transceiver such as a radio modem (for example, a Wireless Futures Bluewave™ or a Zigbee™ radio transceiver). Alternately, a wire-based communications driver 107 can be used. This communications driver 107 also provides a serial data communication interface for the connection of a pulse oximeter sensor 110 to the monitoring device.

[0302] With reference to FIG. 10, the cardio respiratory enumeration is computed according to the states and transitions shown. On application of power to the sensor, it will start at the UNKNOWN state 220 until it has completed its self-checks to determine the unit is working correctly and connected to a body. It will then transit into the NORMAL state 200, via 280. In the NORMAL state 200 it will monitor: [0303] a user's heart and respiration rate per minute (HR and BR); [0304] short-term near-instantaneous heart rate (HRst); [0305] short-term near-instantaneous breathing effort rate (BRst); [0306] long-term average heart rate over a number of different time windows (HRlt); [0307] the rate of change of heart rate over a time window; and, [0308] optionally, a user's blood oxygen level (Sp02).
The device will then compare these levels against a series of configurable thresholds and values, for example, as shown in the following table and if necessary it will determine a transition to an alert state.

TABLE-US-00001 Parameter Description Range Heart Rate High Upper limit for average heart 0 - No Limit Threshold rate per minute 1-255 beats per min (bpm) Heart Rate Low Lower limit for average heart 0 - No Limit Threshold rate per minute 1-255 bpm Breathing Rate Upper respiration limit for 0 - No Limit High Threshold average respiration rate per 1-255 bpm minute Breathing Rate Lower respiration limit for 0 - No Limit Low Threshold average respiration rate per 1-255 bpm minute Short-Term Heart Time period over which a short 0 - None Rate term average heart rate is 1-255 (HRst))TimeWindow measured in order to provide seconds an early indication of failure to detect any heart beats Short Term Time period over which a short 0 - None Breathing Rate term average breathing rate is 1-255 (BRst)TimeWindow measured in order to provide seconds an early indication of failure to detect respiration effort Sp02 Min Lower limit of adequate blood 0-100% Threshold oxygenation Long Term Heart Upper limit for an average 0 - No Limit Rate heart rate or rates measured 1-255 bpm (HRlt)Threshold (s) over several different time window Heart Rate Max Maximum change in heart rate 0 - No Limit Rate Threshold without ambulation which may 1-255 bpm occur over time threshold 6 Time Threshold 1 Time required for an out of 0 - threshold rate to exist before Infinite an indication is raised 1-255 minutes Time Threshold 2 Time period when HR(st) = 0 0-255 before an indication is raised seconds Time Threshold 3 Time period that BR(st) = 0 0-255 before an indication is raised seconds Time Threshold 4 Time period to indicate 0 - sustained absence of vital Infinite signs. 1-255 minutes Time Threshold 5 Time period when HR = 0 and 0 - BR = 0 after which we indicate Infinite the high alert (red) state 1-255 minutes Time Threshold 6 Time period over which we 0 - measure if we exceed HR Max Infinite Threshold Change and an 1-255 exception condition is raised seconds Time Threshold 7 Time period that Temp >39 or 0-255 mins PSI is > PSIMax before an indication is raised Time Threshold 8 Time Period that we will wait 0-255 mins for a neurological stimulation test response Temp Hi Threshold Surface temperature measurement 0-45 deg C. (chest) upper limit for safe temperature regulation PSI Max Modified physiological strain 0-10 index incorporating surface temperature and heart rate measures MPSI Heat Strain 0 1 No/little 2 3 Low 4 5 Moderate 6 7 High 8 9 Very high 10

[0309] If a users condition recovers back to within the boundaries defined in the sensor configuration, the welfare indication will return, via 204, to NORMAL 200. Those skilled in the art can see that the separation of certain combinations of physiology offers higher alert priority 205, 206, 207 to more immediately serious vitals signs states. Additionally, the detection of a condition known as ventricular fibrillation 206 is specifically identified for the same reasoning. In the alert states a neurological response test is automatically triggered and if the result is positive the indication transitions 216, 217, 218 to NORMAL 200. If the user indicates the need for assistance in his response the indication will remain or move to the ALERT 230 state, via 212,213. In the PRIORITY ALERT state 240, if the user condition does not recover by a time threshold then the indication will move to a SUSTAINED ABSENCE OF VITAL SIGNS 250, via 209. In the PRIORITY ALERT 240 or SUSTAINED ABSENCE OF VITAL SIGNS 250 state the detection of ambulation will cause the indication to transition to UNKNOWN 220, via 208,210, as this is inconsistent with the physiology being recorded.

[0310] Referring to FIG. 11, the secondary welfare indication is provided alongside the cardio respiratory welfare indication. The indication provides two alerts THERMAL ALERT 260 and NEUROLOGICAL RESPONSE ALERT 270. If a thermal exception is detected either due to the physiological index exceeding the configured value in the sensor or the skin temperature exceeding the maximum skin temperature, for a defined time period, then the indication will transition to this state 260, via 252. If this exception clears, then the indication will return to NORMAL 200, via 253. If the indication is in the NORMAL state 200 and a high gravitational shock to the body has been detected, a neurological test will be triggered and if no response is received within a defined time period and no ambulation is also detected then the indication will move to the NEUROLOGICAL RESPONSE ALERT state 270, via 256. The state may be cleared if subsequent ambulation is detected, or the user responds to a repeated neurological stimulation test, and the state is returned to NORMAL 200, via 257.

[0311] In all states, if the sensor detects a hardware failure which means its operation cannot be considered reliable, or the overall confidences in the cardio respiratory measures is reduced beyond a point where they may be inoperative, then indication will change state via transitions 215,214,211,201,254,255 to UNKNOWN 220.