Carefusion 207, Inc.

Nicolet Instrument Corporation

Viasys Healthcare, Inc.

Cardinal Health 209, Inc.

Daniel J Lombardi

Eric Garz

William J Lutz

William Kolasa

Steven Vos

Geoffrey Reber

A cable for enhancing biopotential measurements, including a core, the core including a first conductive line, a first shield that surrounds the first conductive line, and a first insulator that surrounds the first shield. The cable further includes a control section located outside the core, which includes a second conductive line, a second shield that surrounds the conductive line, and a second insulator that surrounds the second shield.

Cable for enhancing biopotential measurements and method of assembling the same

Amplification of an evoked potential signal is carried out utilizing a high pass filter implemented as an integrator in a feedback loop which drives the DC offset voltage to zero. As a result, the feed-forward amplifier circuit has almost zero volts at its output since the only voltage remaining is the offset voltage of the operational amplifier, which is selected so as to maintain this parameter as low as possible. Because the voltage impressed across the feed-forward amplifier section is close to zero, the gain of this section can be set to zero during the time that the electrical stimulus pulse is present without introducing any additional artifacts and subsequent amplifier stages are not driven into saturation. When the electrical stimulus potential is no longer present or is significantly reduced in amplitude and before the time of receipt of the response signal, the feed-forward amplifier is brought back into the circuit to provide the high gain required to amplify the response signal, which can be measured without interference from saturation of any of the amplifier stages as they recover to baseline.

Method and apparatus for stimulus artifact suppression

A combination referential and differential amplifier circuit for a medical signal monitoring system includes a plurality of electrode inputs, including at least one reference electrode input, a plurality of medical signal amplifiers, and switching means for selectively coupling each of the plurality of electrode inputs to each of the inputs of the plurality of medical signal amplifiers. Each electrode input may be selectively coupled to several amplifier inputs. The output of a medical signal amplifier with the amplifier inputs thereof coupled to electrode inputs, neither of which is a reference electrode input, produces a differential amplifier signal output. A medical signal amplifier with the inputs thereof coupled to electrode inputs, one of which is the reference electrode input, produces a referential signal output. Thus, a combination of differential and referential electrophysiologic signal channels may be provided.

Combination referential and differential amplifier for medical signal monitoring

A method and apparatus for stimulating evoked potentials in a human subject maintains the common mode voltage at the stimulation electrodes substantially constant both before and during application of a stimulus pulse of constant current. A pair of resistors are connected between the stimulation electrodes and are joined at a reference node. One stimulation electrode (e.g., the anode) is connected through a field effect transistor to the power supply voltage and the other electrode (e.g., the cathode) is connected to the supply common return through a transistor which, when turned on, is controlled to conduct a constant current. The voltage at the reference node is supplied to the gate of a second field effect transistor which has its source clamped to a reference voltage. The voltage at the drain of the second field effect transistor is suppled back to the gate of the first field effect transistor. The two field effect transistors cooperate to supply a voltage to the anode electrode which is controlled such that the voltage at the reference node remains substantially constant before, during and after the switching transistor switches to provide a stimulation pulse. The common mode voltage at the anode and cathode is thus maintained substantially constant during stimulation pulses to minimize stimulus artifacts at the sensing electrodes.

Growing community of inventors

Verona, WI, United States of America

Daniel J Lombardi