GB2465817A

GB2465817A - CPR feedback system

Info

Publication number: GB2465817A
Application number: GB0820508A
Authority: GB
Inventors: Rashid Mazhar; Umar Rashid
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-11-10
Filing date: 2008-11-10
Publication date: 2010-06-09
Also published as: GB0820508D0

Abstract

An apparatus provides feedback during cardiopulmonary resuscitation (CPR) regarding the adequacy of the pulse generated by the action of chest compressions (e.g. to avoid brain damage). The apparatus comprises a non-invasive sensor B to measure parameters of the generated pulse (pressure, flow & rate), and a processing and display unit F. The sensor registers the pressures generated above a pre-determined, threshold, "optimum" blood-pressure. The sensor may be placed in an inflatable cuff A or adhered to the body along the course of an artery using base B. Inflatable cuff may include a local processing and display unit D. The display provides feedback on the number of pulses provided that are of sufficient quality. Feedback may be in various forms (e.g. visual, audible). Measured data is stored and transmitted, either locally or remotely.

Description

TECHNICAL FIELD:

The invention relates to emergency medical devices used in the field of cardiopulmonary resuscitation (CPR) of patients with cardio-respiratory arrest.

BACKGROUND:

Chest compression is an essential part of CPR during cardiac arrest. It aims at maintaining circulation until expert help and gadgets arrive and heart could be revived to pump on its own. Chest compression provides the mechanical force to start and maintain a circulation of otherwise stagnant blood. It is also now known to help oxygenate the patient by moving significant amount of air in and out of the chest, giving rise to the trend of "compression alone CPR". Each chest compression squeezes the heart between the sternum and the vertebral column to produce a pulse.

The main target of this generated pulse of oxygenated blood is the brain. It is the neurological preservation during CPR which is most relevant from the morbidity and mortality view point. While minimum coronary artery perfusion pressure required for survival of the myocardium is only 15 mm Hg; a cerebral perfusion pressure of 30 mmflg, corresponding to an Aortic/Carotid pressure of 55-60 mm Hg is required to avoid significant neurological injury during CPR. Hence if CPR is being conducted in such a way that an "adequate" cerebral perfusion is maintained, the heart muscle is protected in tandem. However the reverse is not true. The ultimate assessment of the value of any CPR is the neurological outcome after the resuscitation. Lack of emphasis on this point and to set a perfusion goal to protect the brain during CPR, currently results in significant number of so called successful revivals (of the heart) with serious brain damage.

The problem with the current way of doing chest compressions during CPR, whether manual or by a mechanical/automated device is that it is an almost "blind" procedure. There is no objective, precise account of the "power or pressure and flow of the pulse" being generated. There seems to be a common reliance upon visual or measured, degree of displacement of the sternum, to a level of 4-5 cm, as stipulated in the resuscitation manuals. However this displacement of sternum with chest compression is only a guideline to the usual desired force needed to produce an "effective pulse". It is by no means a certainty that by moving the sternum to this level a viable pulse, good enough for cerebral protection is being generated. A thin person with shallow chest may not need such force to displace the sternum to a predetermined 4-5 cm and in fact unnecessary and harmful force may he applied to the patient and vice versa. Another relevant example is of a hypovolaemic person in whom any degree of force and displacement of the sternum and chest wall may not produce the "effective pulse" while the CPR is apparently effective, if one relies upon the rule of 4-5 cm displacement of the sternum.

The only available method, at present, to the leader of the CPR team is to clinically check a pulse, with ongoing chest compressions, to make sure that a pulse is being generated. This method however is highly erratic; a pulse present may not be felt and vice versa, especially during the movements and shaking involved in CPR.

Furthermore, clinical check on the pulse is highly unreliable in judging its pressure, flow and hence the quality.

In summary, at present CPR is conduced without an objective assessment and feedback of the quality of the pulse being generated by the action of the chest compressions. It leaves the resuscitator in darkness whether the CPR is achieving its desired objective, a pulse which produces adequate cerebral perfusion or not. This void contributes to a large number of death and disability seen after CPR at the present times.

STATEMENT OF INVENTION:

To overcome this, the present invention proposes a system of surface sensing the rate, pressure and flow generated in the pulse of an artery, during chest compressions. A system is provided whereby the pressure, flow and the rate of the pulse is monitored against a range of pre-determined values, deemed desired or optimal, for a viable perfusion.

There is provided a system whereby the resuscitator would be visually/audibly informed, if the pulse generated by chest compressions is "adequate"/"optimum" or otherwise, in terms of rate, flow and the force of the arterial pulse produced by the compressions.

There is also provided a system of storing, displaying, transmitting and printing this data by an attached or remote monitor or computing device.

ADVANTAGES: The present invention provides an objective measurement and display of the pressure, flow and the rate of the PULSE generated by the chest compressions.

It would display the number of "adequate" compressions per unit time, which are above a pre-determined pressure level which is desirable or optimal for cerebral, cardiac and systemic circulation and viability.

The feedback system is provided with means to store, display, print and transmit the data; visually, audibly, digitally or graphically, locally or remotely, from a single or multiple sensors and processing units.

Unlike the other CPR feedback systems, the present invention is directed towards the quality of the generated pulse, rather than the action of chest compression itself. It provides a feedback on the quality and efficacy of the pulse, rather than the action of the chest compression generating the pulse. It warns the resuscitator, in a real-time and interactive way, of suboptimal or ineffective pulses, as judged from a set of pre-determined values on pressure, flow and rate of an "optimal" and adequate pulse.

INTRODUCTION TO DRAWINGS:

An example of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 shows a sketch of a victim's torso undergoing CPR with one particular embodiment of the CPR feedback system wrapped around the left arm, including the inflatable cuff with attached sensor and the associated processing-cum-display unit as well as a distant processing-cum-display unit.

Figure 2 shows a sketch of a victim's torso undergoing CPR with one particular embodiment of the CPR feedback system where the sensor units, carrying data sensing, displaying and transmitting means, are applied along the course of an artery along with a distant processing-cum-display unit.

Figure 3 shows one of the embodiments of the sensor part of the CPR feedback system.

Figure 4 shows a cross-section of one of the embodiments of the sensor along with some of its main components.

Figure 5 shows one of the embodiments of the mounting platform of the sensor with a sticking base and a removable cover.

Figure 6 shows one of the embodiments of a stick-on inflatable cuff, upon which is mounted at least one sensor and an associate processing/display/storage/transmission unit.

Figure 7 shows one of the embodiments of the processing-cum-display unit with its external features.

Figure 8 shows the cross-section of one of the embodiments of the processing-cum-display unit with its main components.

DETAILED DESCRIPTION:

Referring to the drawings the CPR feedback system comprises of figure 1, where one particular embodiment of the CPR feedback system is shown with an adjustable inflatable cuff A' wrapped and secured around the arm of the victim. The cuff A' has attached to it at least one sensor B' provided with the means to sense the pressure, flow and rate of the pulse generated by the action of chest compressions C', either by manual or mechanical means. The inflatable cuff A' has attached on it an associated processing-cum-display unit D' which has display surfaces E' to display the actual as well as processed data, in digital, graphic or auditory format. The unit D', stores, analyses and transmits the data to a distant processing-cum-display unit F'. The unit F' receives its data from the unit D' as well as from sensor B' for processing, storing, displaying and printing the same.

In figure 2, one particular embodiment of the CPR feedback system is shown where the sensor units B', provided with the means to sense, process, display and transmit the pressure, flow and rate of the pulse generated by the action of chest compressions C', either manual or mechanical, are applied along the course of an artery. The figure also shows a distant processing-cum-display unit F' to which the sensors B' send its data either by wired or wireless means. Here the sensors B' are mounted on the base G', with an adhesive undersurface, covered by a peel able cover, which is applied to the skin surface.

Figure 3 shows one of the particular embodiments of the external view of the sensor B' depicting an encased body H' with a sliding, clip-on base I' and a display screen/portal J' which displays auditory/visual prompts and data.

Figure 4 shows a cross-section of the embodiments of the sensor B' as depicted in figure 3 along with some of its main components. It shows the pressure/flow/rate sensor K' overlying an air/fluid filled interface L', which is pressurized to a pre-determined level by the pump M', driven by the on board power source N'. There is also depicted means of data storage, 0', data transmission P', circuitry for data processing Q', auditory portal R' for signals &/or interactive linguistic feed back and visual display means S' displaying with light flashes, data values &/or graphs.

Figure 5 shows an embodiment of the mounting platform G' of the sensor B' as depicted in the figures 2 & 3. The platform is provided with a central gap T' for the air/fluid filled interface L', as depicted in figure 4. It is also provided with a locking mechanism U' for the clip-on base I' of the sensor B', as well as a sticking base with an underlying removable cover V'.

Figure 6 shows one of the embodiments of the sensor B' as depicted in figures 2, 3 & 4 mounted on the platform G' depicted in figure 5.

Figure 7 shows one of the embodiments of an inflatable, adjustable, cuff A', as shown in figure 1, upon which is mounted at least one sensor B' as shown in figures 1-4 and an associated processing/display/storage/transmission unit D' as shown in figure 1, with some of its external features, thus depicting display areas/portals E' to display the actual as well as processed data, in digital, graphic &/or auditory format. The embodiment also depicts a means W', for setting up and changing the pre-determined, "optimum" or adequate levels of the pulse rate, flow and pressure.

Figure 8 shows the cross-section of one of the embodiments of the processing-cum-display unit D' as shown in figures 1& 7 with some of its components, thus depicting the pump M', driven by the on board power source N'. There is also depicted means of data storage, 0', data transmission F', circuitry for data processing Q', auditory portal R' for signals &/or interactive linguistic feed back and visual display means S' displaying with light flashes, data values &/or graphs as well as a means W', for setting up and changing the pre-determined, "optimum" or adequate levels of the pulse rate, flow and pressure.

With reference to the figures 1 to 8, which represent only a selected embodiment of the invention, it is expressed that the scope of the invention is to assess the quality and the effectiveness of the pulse which is produced during CPR, whether the chest compressions are done manually or mechanically. The hitherto presented "CPR feedback system" may be a self-contained unit, as shown in the figures 1 & 7, which may have data processing, storage, printing and displaying means as well as links with a distant display unit F', as depicted in figure 1.

The sensor B' may be part of the unit, with an interface A' and an associated processing-cum-display unit D' as depicted in figures 1 & 7 or it may be an independent, sensing, processing, transmitting and displaying unit as shown in figure 2, with means of communicating the data to a distant unit F', for processing, storing, printing, displaying, transmitting and for visual and auditory, interactive feedback to the rescuer.

The processing-cum-display units, either associated as in item'D' of the figure 1 & 7 or a distant one, as in item F' of figures 1 & 2, process and display the produced rate, pressure and flow data of the pulse generated by the action of the chest compressions and at the same time compare these data with a predetermined set of desired "adequate" and "optimum" values, thus deducing the number of "effective" pulses produced by chest compressions. The rescuer would receive feedback in the form of auditory signals, spoken language &/or visual display of numbers, flashing lights and graphic display, through the display portals provided, exemplified by item E' in figures 1 & 7, and items S' & R' in figures 4 & 8.

When the sensor B' is used as a stand-alone device as shown in figure 2, it is also provided with a visual/auditory means of display of the above mentioned information by means of visual and auditory portals as shown in item J' of figure 3 and items S' & R' of figure 4.

The processing-cum-display units, either associated as in item'D' of the figure 1 & 7 or a distant one, as in item F' of figures 1 & 2 are provided with the mean, as depicted in the item W' of figures 7 & 8, to select the predetermined parameters in terms of pressure, rate and flow of the generated pulse. This provision would be of use for in-vitro training, research and quality assurance purposes.

The feedback received by the rescuer would allow them to correct the CPR quality towards the "desired" and the "optimum" parameters.

Thus the preferred embodiments of the present invention has been described in reference to their application environment; however these depictions are merely illustrative of the principles underlying the present invention. Other embodiments, designs and configuration may be devised without departing from the principles, spirit and scope of the appended claims.

Claims

CLAIMS: 1: A CPR feedback system regarding the pulse generated by the action of chest compressions, either manual or machine-aided, comprising a measuring means, a processing means and a display, storage and transmitting means, where the sensing/measuring means comprises sensor/s capable of recording the arterial pulse dynamics, the processing means comprises a pressure, flow, pulse rate and threshold sensing circuitry and the display means comprises provisions for storage, display, printing and transmission of the received and processed data.

2: A CPR feedback system according to the claim 1, where the measuring means is provided by at least one, pressure, flow characteristic and rate sensor, for the generated pulse, functioning on mechanical, electromechanical, photometric or ultrasonic principle.

3: A CPR feedback system according to the claim 1, where the measuring means comprise sensor/s which senses the maximum and the minimum pressure, flow and rate produced in the pulses generated by the chest compressions.

4: A CPR feedback system according to the claim 1, where at least one measuring sensor is mounted either through an air/fluid or other suitable interface or applied directly to the body of the patient along the course of an artery.

5: A CPR feedback system according to the claim 4, where in one specific embodiment the measuring means is provided with at least one sensor which is mounted on an adjustable air/fluid inflatable cuff placed around the limb of the patient.

6: A CPR feedback system according to the claim 5, where the inflatable cuff is provided with means of inflating it to, and keeping it at, a pre-determined "threshold" pressure, allowing the sensor to monitor the pressure in the pulse above that threshold.

7: A CPR feedback system according to any of the preceding claims where the measuring sensor is capable of transmitting the data to the processing means, either by wired or wireless means.

8: A CPR feedback system according to the claim 1, where the processing means comprises a maximum and minimum pressure, flow characteristic and rate sensing circuitry and means for comparing it to a set of threshold values.

9: A CPR feedback system according to the claim 8, where the processing means comprises provision for selecting, changing and adjusting all or one of the threshold values.

10: A CPR feedback system according to the claim 8, where the processing means comprises provisions for constantly comparing the data received from the sensing means against the pre-determined "optimum" threshold values for the pressure, flow and rate of the pulse, deducing the number and rate of "optimum" pulses generated.

11: A CPR feedback system according to the claim 8, where the processing means comprise provision for a system of storing the data from the sensing means along a time recording.

12: A CPR feedback system according to the claim 8, where the processing means comprise provision for a system of transmitting the received and stored data to other data storage devices, fixed or detachable, to other computers or distant display means, either by wired or wireless means, either in stored form or in real-time.

13: A CPR feedback system according to the claim 1, where the display means comprises provisions for visual and/or auditory display of the data received from the measuring means.

14: A CPR feedback system according to the claim 13, where the display means comprises provisions for displaying real-time, ongoing, as well as recorded data over a period of time.

15: A CPR feedback system according to the claim 13, where the display means comprises provisions for displaying the data in the form of light indicators, digital numerical display and digital graphic format.

16: A CPR feedback system according to the claim 13, where the display means comprise provisions for displaying the actual rate, pressure and flow of the pulse as well as the number of "optimum" pulses generated which are at or above the pre-determined threshold values, either in absolute or in relative terms.

17: A CPR feedback system according to the claim 13, where the display means is provided with provisions for giving auditory display in signal format or in various spoken languages' format.

18: A CPR feedback system according to the claim 13, where the display means comprises provisions for printing the data being displayed.

19: A CPR feedback system according to the claim 13, where the display means comprise provisions for a real-time, interactive, visual or spoken prompt to change the speed and/or force of the chest compressions to a predetermined optimal level.

20: A CPR feedback system according to any of the preceding claims where the system could be a stand-alone device, or it could be linked to, or be part of an automated chest compression &/or ventilatory device.

21: A CPR feedback system according to any of the preceding claims where the system would provide clear, recordable, transmittable, audiovisual, interactive information about the quality of all the pulses generated by the chest compressions, and to display the absolute number and/or the ratio of the "optimum" pulses, per unit time, which are at or above the pre-determined "optimum" level, in terms of pressure, flow and frequency.