Respiration Motion Detection and Health State Assesment System

Abstract

A wearable platform embodied in a belt or flattened patch-like central body shaped to conform to the abdomen provides physiological monitoring of soldiers during field operations or trauma victims at accident sites and makes health state assessments. The platform includes sensors for heart rate, body motion, respiration rate and intensity, and temperature and further contains a microprocessor and short range transmitter. The respiration sensor uses conductive ink in a novel manner. A small square of the ink is coated on an arched structure so that flexing of the arch either to increase or decrease its radius of curvature modifies the resistance of the structure. This is utilized to set the unstressed resistance of the arch structure and to allow a greater range of resistance values capable of measuring distortions in different deformations of the arch. The respiration sensor supplements the motion information provided by an accelerometer sensor.

Description

[0001] This patent claims the benefit of the priority of Provisional Patent Application 60 / 517,149, filed Nov. 4, 2003 and entitled “Life Sign Detection and Health State Assessment System”, the full disclosure of which is incorporated by reference.FIELD OF THE INVENTION [0002] This invention relates to compact wearable systems for measuring a subjects vital signs, such as respiration rate and motion, processing those measurements and transmitting the results of the processing wirelessly for remote monitoring. It also relates to specific sensor transducers and processing algorithms for generating electrical signals indicating vital signs, and more generally for developing diagnostic information from groups of sensor readings. BACKGROUND OF THE INVENTION [0003] Electronic devices for monitoring a patient's vital signs at bedside are in common use in hospitals. Typically these measure, display and transmit to nursing stations EKG traces, blood pressure values, body temperature values, ...

AI Technical Summary

Benefits of technology

[0055] An additional component, called the Local Hub, is also worn by the subject. In its simplest form the local hub contains an RF receiver, a medium or long range RF transmitter or transceiver, and a microprocessor. The local hub receives the transmitted data from the LSDS wearable package and retransmits the signals to a remote station or base station. Retransmission is not necessarily synchronous with reception; the microprocessor may perform additional processing on the received data and may reconfigure the data for more efficient transmission.

[0084] It is a still further object of the invention to provide the electronics that allows most processing to take place on the PC board including in the sensor housing. This local processing reduces the bandwidth requirements for transmission, since it is not necessary to transmit waveforms for remote analysis. In addition the electronics are designed to conserve battery power to enhance the battery lifetime.

Problems solved by technology

In particular there do not exist devices that could be worn by a soldier in the chaotic battlefield environment to provide enough useful information on vitals to say with confidence that the soldier is beyond the point where medical intervention would be useful, so as to be able to terminate rescue attempts that place a rescuer's life in jeopardy.

Thus medics and other rescue personnel have been killed or seriously injured attempting to rescue soldiers where rescue was already hopeless.

Despite the great need for systems to avoid such unnecessary casualties there has heretofore been no satisfactory system economical enough to provide to large numbers of armed forces.

For example ambulances and emergency vehicles are often equipped with diagnostic equipment that can be overwhelmed in situations where there are several injured to treat simultaneously.

Again, there is not available at reasonable cost health assessment systems that could be applied to multiple subjects to allow triaging to take place rapidly by persons remote from the scene of injury.

Nevertheless, despite these suggestions and the great need, the prior art has not advanced to the point where such systems have been built and made practical.

However, there are significant limitations in the respiration sensors disclosed in the prior art.

There are a number of deficiencies in these types of devices: The piezo element is only moderately expensive, but it requires means for making electrical connections, attachment to a flexible belt, and pre-setting with a correct amount of flexure to operate properly.

These all add to the cost of the application.

This adds additional cost to the application and may cause susceptibility to electrical noise interference.

Typically the decay time constant is on the order of 5 seconds, so it is difficult to accurately reproduce a waveform with a frequency of less than 0.2 Hz.

Conversely, the piezo element produces a large output signal at high frequencies and requires extensive filtering to remove extraneous high frequency components from the signal.

The rubber strip type of sensor can produce a fixed voltage output, but is also has a very low output level because the amount of elongation during breathing is a very small fraction of the overall length.

However, it has the disadvantage that the belt must be specially constructed for, and be an integral part of the application.

The belt cannot easily be detachable or be an ordinary commercial component.

Other types of respiration sensors do not appear to be well suited for the types of applications described above.

Sensors that are placed adjacent to the mouth and nose and which measure air velocity or oxygen and carbon dioxide content are obtrusive, expensive, and generally impractical for field applications.

Further, the device is highly sensitive to any externally applied compression such as may occur if the subject is reclining or carrying an object so that it presses against the abdomen.

The deficiencies of this type of device are several.

The pressure sensor adds significant cost.

They tend to be imprecise because they employ resistive material distributed along the length of the flexible element, which can bend or twist at any point.

They are capable of measuring rotational motion but not force or torque loads and cannot directly sense linear motion or loads.

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