Patent Publication Number: US-2009227849-A1

Title: Medical Instrument

Description:
RELATED APPLICATIONS 
     This application is a Continuation of PCT application serial number PCT/IL2007/001087, filed on Sep. 4, 2007, which in turn claims the benefit under 35 USC 119(e) of U.S. Provisional Application No. 60/842,159, filed on Sep. 5, 2006, both of which are incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The invention concerns a medical instrument that is adapted for receiving physiological signals from the body of a subject and which is adapted for communication with a computer for the purpose of analysis, storage and display of the recorded signal or a processed product thereof. 
     BACKGROUND OF THE INVENTION 
     It is a trend is modern medicine to transfer many of the medical and diagnostic procedures hitherto performed in hospitals or specialized clinics, to a doctor&#39;s office. Additionally, there is also a trend to switch medical instruments from a stand-alone configuration into a configuration in which they are integrated with a computer. For this the instrument has to be provided with some means for interfacing with the computer. For a doctor&#39;s office use as well as for use in the medical facility without specialized computer technicians, such interfacing should be designed to be relatively simple. 
     Hitherto, computer-interfacing medical instruments were typically provided as separate units connectable to a computer via one of the computer&#39;s standard communication ports. 
     SUMMARY OF THE INVENTION 
     The present invention provides a new design for a medical instrument of the kind that is adapted to receive signals representative of physiological signals and transmit them, typically after initial processing, to a computer. In accordance with the invention such a medical instrument is provided with a housing configured such that it can be installed in a compact disc (CD) drive bay of a computer, typically a portable computer, e.g. of the kind usually referred to as “laptop” or “notebook” computers. 
     Thus, in accordance with the present invention there is provided a medical instrument comprising a housing, a first communication utility in the housing for receiving input signal indicative of physiological signals and a second communication utility for communicating with a computer, said housing being configured for removable installment in a CR drive bay of a computer. 
     The term “medical instrument” means to denote any instrument that is intended to record physiological signals and includes, but not limited to, medical instruments intended to record cardiovascular parameters. In addition, the medical instrument may be adapted for recording of brainwaves, parameters of the skin, parameters indicative of tissue composition, sound signals from various body parts, etc. As will be appreciated, the invention is widely applicable and is not limited for the aforementioned medical applications. 
     The first communication utility comprises, according to an embodiment of the invention, one or more signal receivers, and optionally initial signal conversion or amplifier stage. Also, according to some embodiments of the invention, the medical instrument may also comprise an emitting utility for outputting a signal, e.g. a stimulating signal, to a subject body, such as a signal generator for emitting a low voltage electrical stimulation signal for inducing evoked potentials in nerves or muscles, an ultrasound transducer for emitting an ultrasound signal, a laser for emitting a light signal, and others. 
     Said second communication utility may, according to one embodiment of the invention, have a port disposed on a face of the housing which is externally accessible when the instrument is in said bay. Said second communication utility, according to such embodiments, may communicate with the computer via a wired or wireless communication connection arrangement. 
     According to other embodiments of the invention, said second communication utility is on a face which, once the instrument is in said bay, is internal, and is adapted for connection to a communication port that is within said bay, e.g. a communication port that is adapted for communication with standard computer accessories. 
     According to an embodiment of the invention, said housing is configured for installment in the bay of a portable computer. Typically, such housing is configured for installment in a bay intended for a CD disc-drive. According to an embodiment of the invention, the housing also houses a processor utility for processing the input signal and generating an output signal corresponding thereto for communicating to the computer. According to some embodiments of the invention, said processing utility is adapted also for receiving control signals from the computer. According to other embodiments of the invention, the medical instrument also comprises an application software utility, e.g. a software utility which is intended to permit the computer to integrate with said instrument. 
     A medical instrument, according to an embodiment of the invention, is adapted for use in determining one or more cardiovascular parameters. The cardiovascular parameters may be one or more of the following: ECG, blood pressure, stroke volume, heart rate or cardiac output. 
     According to an embodiment of the invention, the first communication utility comprises two or more signal receivers, each for receiving an input signal indicative of a different physiological parameter. According to a specific embodiment, said first communication utility comprises a first receiver for receiving a signal indicative of a parameter relating to cardiac output, a second receiver for receiving a signal indicative of an ECG and a third receiver for receiving a signal indicative of blood pressure. 
     The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       In the accompanying drawings, reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale; emphasis has instead been placed upon illustrating the principles of the invention. Of the drawings: 
         FIG. 1  is a schematic illustration of a medical instrument in accordance with an embodiment of the present invention; 
         FIG. 2A  is a block diagram illustrating the main elements within the medical instrument in accordance with an embodiment of the invention and its connectivity to external measurement unit and to a host computer; and 
         FIG. 2B  exemplifies more specifically an embodiment of the bioimpedance unit of the medical instrument of  FIG. 2A . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     Reference is made to  FIG. 1  illustrating schematically an example of a medical instrument  10  according to the present invention. The medical instrument of the present invention is designated as a so-called Medical Gear In Contrivance (MEGIC) device. Instrument  10  includes a housing  12  configured for removable installment in a standard CD drive bay  14  of a computer, e.g. that of a portable computer such as a Laptop. Housing  12  includes a first communication utility  16  for receiving one or more input signals, two such signals IS 1  and IS 2  being considered in the present specific but not limiting example, and includes a second communication utility  18  for communicating with a computer  20 . Input signal(s) is/are indicative of physiological signal(s). 
     It should be noted that generally the first communication utility may be formed by a single port for receiving one or more input signals. In the present example, two such ports  16 A and  16 B are shown. The use of multiple receiving ports might be associated with concurrent receipt of multiple different input signals, or with a need for selective operation of either one of them, for example when the other is being corrupted, as the case may be. 
     Second communication utility  18  also may be formed by one or more ports—one such port being shown in the present example. Second communication utility  18  is adapted for communication via a connection unit  22  to a communication port  24  of the computer. In the present example, such a connection unit is a wire-based connector, but it should be understood that wireless communication can be used as well. 
     In the present example, the ports of first and second communication utilities  16  and  18  are located on a face  12 A of the housing which is externally accessible once the instrument is in the computer bay. It should however be noted that at least some of the ports of the first and second communication utilities, typically that associated with connection to the computer&#39;s utilities, may be located on a face of the housing which is internal once the instrument is in the bay. A connection base in a computer, such as that known as a laptop or notebook computer, is generally equipped with standard internal communication ports adapted for connection with counterpart connectors in computer accessories which are intended for installment in such ports. According to embodiments of the present invention, the medical instrument may be fitted with corresponding connection ports which then connect into the standardized connection ports within the base. 
     Housing  12  includes a processor utility (not shown in  FIG. 1 , and described further below with reference to  FIG. 2A ) for processing the input signal(s) IS 1 , IS 2  and generating an output signal OS to the computer. The processor utility features are appropriately set for the requirements of various applications of the invention, for monitoring various physiological parameters of individuals. 
     In some embodiments of the invention, the processor utility of the medical instrument operates as an application program interface utility between the computer and external measurement unit(s), while the data processing is mainly carried out by the computer. For example, the processor utility can perform the signal amplification, filtering, etc. In some other embodiments, the processor utility is installed with a certain software product operating to perform the entire medical data processing, and the computer serves for displaying the processing results and provides a user interface for operating the medical instrument, data storage, etc. In yet another embodiment of the invention, medical instrument  10  includes an application software utility configured for the so-called distributed data processing in integration with said computer. 
     In a specific non-limiting example of the invention, medical instrument  10  is adapted for use in determining one or more cardiovascular parameters of a patient. The cardiovascular parameters may be one or more of the following parameters: ECG, blood pressure, stroke volume, heart rate or cardiac output. 
     Reference is made to  FIGS. 2A and 2B  showing schematically the internal components of a medical instrument according to an embodiment of the invention.  FIG. 2A  shows the components of the processor utility  100  of a medical instrument, according to an embodiment of the invention and  FIG. 2B  shows more specifically a bioimpedance unit of the processor utility. 
     Processor utility  100  includes a bioimpedance unit  30  constituting a signal receiver, and a microcontroller  32 . Bioimpedance unit  30  is connected at its input end to input port  16 A of the medical instrument and is connected at its output end  33  to microcontroller  32 . Bioimpedance unit  30  is configured for receiving and performing the processing of an electrical output IS 1  from an electrodes&#39; unit  35 A on a patient P for determining the patient&#39;s cardiac parameters, such as stroke volume. In a non-limiting example, processor utility  100  also includes another signal receiver  34  for receiving, via an input port  16 B, an input signal IS 2  from an ECG-related electrodes&#39; unit  35 B. In the present example different input signals are received by different input ports, but it should be understood that this is an optional solution, and all the signals can be input through the same port. Also, in this example, the medical instrument receives, through either one of ports  16 A and  16 B, an input signal IS 3  from a non-invasive blood pressure (NIBP) measurement unit  36  (wire or wireless). 
     The outputs of microcontroller  32  are connected to an output port ( 18  in  FIG. 1 ) of the medical instrument connected to a HOST processor  40  of the computer ( 20  in  FIG. 1 ). This connection may be implemented via an isolation data unit  42  (such as opto-isolators HCPL2611HP), and via a Driver circuit  44  (such as the driver RS232C or USB) and suitable interface utility  46 . Alternatively the connection may be through dedicated port in the instrument that connects to a standardized connection port in the bay. These connection elements may be part of the medical instrument and/or the computer. As indicated above, the connection between the medical instrument and the computer may be wire-based or wireless. In the latter case, the medical instrument and the computer are appropriately provided with IR and/or RF and/or acoustic transmitter/receiver. Such communication techniques are known per se and therefore need not be described in detail herein. The medical instrument of the illustrated embodiment is power supplied (e.g. +5V) from the HOST processor via an isolating DC/DC circuit  48  and feeding a power supply unit  50  which stabilizes the voltage value. In the present not limiting example, the processing is a distributed processing, namely bioimpedance unit  30  and local microcontroller  32  perform certain initial processing (as will be described below with reference to  FIG. 2B ), while HOST processor  40  performs the final processing, which includes analysis of the measured signal, selection of a model (which is stored in a memory utility of either computer  20  or medical instrument  10 ) for calculation, and calculation of the desired parameter(s). For example, the cardiac parameter(s) may be calculated based on the models utilizing the ΔR/R volumetric parameter and the ((dR/dt)·T) blood velocity parameter. To this end, the known Frinerman formula (see U.S. Pat. No. 5,469,859 assigned to the assignee of the present application) and the dR/dt-based equation [Kubicek et al. Biomed. Eng. 1974, 9:410-16] can be used for the stroke volume calculation. The principles of these bioimpedance measurement techniques are known per se and therefore need not be specifically described. 
     An example of the construction and operation of bioimpedance unit  30  will now be described with reference to  FIG. 2B . As indicated above, this is a specific but not limiting example of the invention configured for use in determination of one or more cardiac parameters of a patient. Bioimpedance unit  30  includes a current source  52  for supplying electrical current to electrodes&#39; unit  35 A, and a direct digital synthesizer (DDS) generator  54 , which is in turn operated by microcontroller  32 . The provision of DDS generator  54  is associated with the following: a human body behaves, from an electrical point of view, as a resistance-capacitance (RC) impedance; the value of impedance is influenced by the injection current frequency; the DDS generator operates to control this frequency to be about 32 KHz. Microcontroller  32  operates the DDS generator to control the stability of the output frequency and amplitude of a sinusoidal signal from the DDS generator, which signal operates current source  52 . Bioimpedance unit  30  preferably includes a leadoff detector  56 , which is used to sense the absence of a contact between the electrode and the body (for bioimpedance electrodes and preferably also for ECG electrodes). 
     A read voltage signal IS 1  from electrodes&#39; unit  35 A is input to a high precision instrumentation amplifier  58 . This input signal IS 1  is proportional to the human body impedance Z (i.e. an integral bioimpedance). An output of instrumentation amplifier  58  is connected to a first input of a synchronous detector  60 . The latter operates to rectify the integral bioimpedance signal, and to provide simultaneous derivation of the active component R of the integral bioimpedance signal vector. This component R is directly proportional to the resistive component of the lead (resistance of the blood system). Linearity of the synchronous detector  60  simplifies the calibration process and reduces it to a single-step initial adjustment of the medical instrument (instead of a per cycle calibration). An output of detector  60  is connected to a low frequency filter  62  which may for example be a low pass Bessel filter. Filter  62  cuts off high frequency components, for example above 32 KHz, and delivers an operating signal, which has the active bioimpedance component (DC) R, and the waveform bioimpedance signal (AC) ΔR. The operating signal is input to an R SCALE AMPLIFIER  64  and to a Bioamplifier and Filter  66 . Amplifier  64  produces an output signal proportional to the active bioimpedance component R and transmits the same to an input ADC (Analog-to-Digital Converter) of the microcontroller  32 . Bioamplifier and Filter  66  separates from the operating signal the waveform ΔR component. The output of the Bioamplifier and Filter  66  is connected to another input ADC of microcontroller  32 . The latter communicates with HOST processor ( 40  in  FIG. 2A ) of the computer. 
     Thus, the present invention provides a novel medical instrument configured to be installable in a standard computer bay, typically a disc drive bay. The medical instrument is preferably constructed as an application program interface for communicating with a measurement unit, such as electrode unit(s), and for communicating with a computer processor. 
     It should be understood that the invention is not limited to the above-described examples of determining cardiovascular parameters, but may be used for determining any other physiological parameters. To this end, the processor utility of the medical instrument is installed with suitable hardware and/or software products to be responsive to predetermined input signals and process them to produce desired output. 
     While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.