BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 illustrates an embodiment of a block diagram of a method of signal acquisition and amplification.
FIG. 2 illustrates a schematic diagram of an embodiment of digital amplifier and acquisition system.
FIG. 3 illustrates a graphical representation of another embodiment of the system of a digital amplifier and acquisition system.
DETAILED DESCRIPTION
The digital signal amplifier and acquisition system relocates the cardiac signal digitization from a point many feet away from the patient, up to the patient's bedside, thereby eliminating a significant amount of noise induced by analog cabling. It has been found that analog cabling causes approximately half of the noise found in current acquisition systems, and current systems include catheter input modules (CIMs) that do not include digitizers, but rather act only as inputs with analog cables that connect to the digitizer, typically in the base several feet away, or attached to the underside of the bed. The present digital signal amplifier and acquisition system also directly converts the analog signal to a digital signal without amplifying the analog signal or applying any band pass filtering, which also reduces a significant amount of signal noise.
FIG. 1 shows an embodiment of the acquisition system 100 that includes one or more catheter input modules (CIM) 102 which have a technical effect to receive incoming cardiac signals from a catheter, and route and digitize those signals. The system 100 will be able to accommodate four such CIMs, each with 30 channels for a total of 120 channels. The catheters (not shown) will connect via the 6, 10-pin connectors 103, in each of the CIMs 102. As illustrated in FIG. 1, all of the CIMs 102 are manually stacked and electrically daisy-chained (FIG. 2) via a short cable on the rear of the CIM 102, and held on the patient's bedside with a mount platter 104. The CIM 102 is a 4 KHz 24-bit sigma delta A/D digitizer, bipolar or unipolar with respect to a Wilson central terminal or auxiliary reference, respectively.
Still referring to FIG. 1, the mount platter 104 is configured to hold and support the CIMs 102, and provide emergency and reference input sources 105, 107, 109. The mount platter 104 utilizes an attachment pole 106 in order to clamp the mount platter 104 to the bedrail of the patient's bed. The mount platter 104 also includes a single CIM cable 108, which provides digital signals from the CIMs 102 to the base 120. The mount platter 104 also includes emergency stimulator connectors 105, as well as an auxiliary reference input 107 and a test signal generator 109. The emergency stimulator connectors 105 provide the ability to utilize the catheters placed in the patient as emergency pacemakers in the event of total failure of the system 100. The emergency stimulator connectors 105 provide for a direct electrical connection to the STIM inputs number 1 and 2 provided on the STIM connector 127 on the base unit 120. The auxiliary reference input 107 allows a physician to build an analog channel without using a catheter and the CIMs 102. In other words, a physician may utilize a device such as a patch on the back of the patient or an electrode in the leg of the patient and plug this device into the auxiliary reference input 107 to provide an additional input. The test input 109 allows a test of any of the CIMs 102 by plugging a connector from the test input 109 into any of the ten pin connectors 103 in any of the CIMs 102 in order to see if the CIM 102 is working properly.
Referring now to FIGS. 1 and 2 the system 100 also includes an acquisition module 110 and a base 120. The base 120 is configured to receive the digital signals from the mount platter 104 through the CIM cable 108 and filters and distributes this acquired data. The base 120 is also configured to give a digital command to the CIMs 102 in order to instruct the CIMs 102 when to digitize the information, and is further configured to package the digital data from the CIMs 102 in order to send it to a PC or outside device for additional processing. The base 120 is preferably mounted on the base of the patient's bed 210 (FIG. 3). The acquisition device 110 is mechanically and electrically coupled with the base, and is configured to collect a number of physiological parameters from the patient such as blood pressure, heart rate, respiratory data, and blood oxygen saturation level. The base 120 includes 8 bipolar simulator inputs which are digitized and routed, 4 analog inputs, which are digitized in synchronous with CIM sampling, 12 lead ECG and 4 IBP analog signals shared with the acquisition module 110, and 16 low-latency analog outputs.
Referring back to FIG. 1, the base 120 includes an analog out 122, which provides a digital signal through the cable 132 to the analog output module 130. The base 120 also includes an analog input 124, a vital sign output 126, a simulator input 127 and a network connection 128. Referring again to FIG. 2, the stimulator input 127 receives inputs from the stimulator 135, while the outside devices 140 send request and receive processed and filtered data from the base 120 for physician review.
The system 100 also includes an analog output module 130. The analog output module 130 is configured to receive a digital signal from the analog out 122 of the base 120 through the cable 132, and reconstruct an analog signal, preferably with up to 16 filtered digital data streams at a time. The analog output module 130 is configured to reconstruct the analog signal for a strip chart recorder, or any other outside device that requires a representation of the signal.
Referring now to FIG. 3, a graphical representation of an embodiment of the system 100 of the present invention is depicted. Here, the catheters 220 are connected into the CIMs 102, which are mechanically stacked and daisy-chained to the mount platter 104. The attachment pole 106 allows the mount platter 104 to be attached to the bedrail of the patient's bed 210, and a single CIM cable 108 allows digital signals to be communicated from the mount platter 104 to and from the base 120. As is shown, the base 120 is mounted on the patient bed 210 and an acquisition device 110 is coupled with the base 120.
The system 100 reduces a large amount of system noise by digitizing the analog signals at a close proximity to the patient, eliminating many feet of analog cable from the systems of the prior art. Furthermore, a large amount of system noise is removed by eliminating analog switching and filtering circuits, which is done by performing all signal processing after the CIMs in the digital domain.
Furthermore, an embodiment utilizes a 4 KHz, 24-bit A/D converter which provides greater than 20 bits of signal resolution when noise is accounted for. This large number of bits provides the system 100 the ability to record signals down to the physiological minimal level of interest of 6 uV over an input range of almost 5 volts. A range and resolution this large allows for recording all data of interest even in non-ideal conditions such as pacemaking or ablating. In other words, the system 100 has a much higher resolution and range than conventional systems.
The system 100 of the present invention also embodies a real-time response. It is important that data be captured and displayed or sent to other equipment as quickly as possible in such systems. The digital base 120 of the system 100 includes a high-speed processor and programmable logic able to receive over 150 channels of data at 24 bits and 4 KHz. Preferably, the data is placed in Ethernet frames and sent at 250 Hz at the same time it is filtered and sent out in analog form in less than 2 mS.
Furthermore, the system 100 of the present invention is versatile from a market standpoint, as it incorporates a set of modular CIMs 102. Preferably, each CIM 102 accepts 60 inputs, captures 30 unipolar or bipolar channels, and the system 100 is configured to support from 1 to 4 CIMs 102. Additionally, two analog outputs are provided on the base 120, and with additional analog output module support, such analog outputs are expanded to 16 outputs.
Subject matter has been described in terms of specific embodiments incorporating details to facilitate the understanding of the principals of construction and operation of the invention. Such reference herein to specific embodiments and details thereof is not intended to limit the scope of the claims appended hereto. It will be apparent to those skilled in the art that modifications may be made in the embodiment chosen for illustration without departing from the spirit and scope of the invention.
Patent Application
20070276272
