CADWELL FOUR-/EIGHT-CHANNEL PREAMPLIFIER

K962458 · Cadwell Laboratories, Inc. · GWF · Jan 13, 1997 · Neurology

Device Facts

• Record ID: K962458
• Device Name: CADWELL FOUR-/EIGHT-CHANNEL PREAMPLIFIER
• Applicant: Cadwell Laboratories, Inc.
• Product Code: GWF · Neurology
• Decision Date: Jan 13, 1997
• Decision: SESE
• Submission Type: Traditional
• Regulation: 21 CFR 882.1870
• Device Class: Class 2

Intended Use

The general purpose of the proposed device is identical to the predicate device: "to perform the measurements needed for electromyography (EMG), nerve conduction velocity (NCV, F wave, and H reflex), and evoked potentials (brainstem, visual, and somatosensory), and repetitive nerve stimulation." The purpose of the proposed device is to allow compatibility with high-impedance electrodes. The design of the device provides inputs that can be made closer to the source of the signal for reduced signal noise during procedures requiring high-impedance electrodes.

Device Story

Device consists of buffered electrode input box with extension cable and cable adapter; designed for use with Cadwell Excel EMG instrument. Input box placed closer to signal source to reduce noise during high-impedance electrode procedures. Input box contains buffer circuit, ESD protection networks, and fault current limiting circuit. Connects to preamplifier via polyvinyl chloride extension cable and adapter. Used in OR or clinic by physicians/technicians. Provides signal input for EMG/NCV/evoked potential measurements. Benefits patient by improving signal quality and reducing noise during electrodiagnostic testing.

Clinical Evidence

Bench and clinical testing performed. Engineering tests confirmed input impedance >10 Mohms after ESD strikes, gain stability, and patient auxiliary current within IEC 601-1 limits for BF connections. Clinical testing (Test 6 and 7) compared nerve conduction and EMG waveforms with and without the device; results showed no distortion of morphology, onset time, peak time, or amplitude.

Technological Characteristics

Materials: white polyethylene foam sheath, polyvinyl chloride cable. Sensing: buffered electrode input. Connectivity: wired connection to preamplifier via DIN connectors. Sterilization: EtO compatible. Safety: Type BF applied part, IEC 601-1 compliant. Input impedance >10,000 Mohms. Noise: 0.6 microvolts RMS typical (10 Hz to 2 kHz).

Indications for Use

Indicated for patients requiring electromyography (EMG), nerve conduction velocity (NCV, F wave, H reflex), evoked potentials (brainstem, visual, somatosensory), and repetitive nerve stimulation studies. Used under direction of trained physician, surgeon, neurologist, or electrophysiologist.

Regulatory Classification

Identification

An evoked response electrical stimulator is a device used to apply an electrical stimulus to a patient by means of skin electrodes for the purpose of measuring the evoked response.

Predicate Devices

• Cadwell Excel (K880088A)

Submission Summary (Full Text)

{0}

K962458

JAN 13 1997

# Section 2 - Summary and Certification

December 20, 1996

## A. 510(k) Summary of Safety and Effectiveness

The proposed device consists of the existing four-/eight-channel preamplifier and a buffered electrode input box with extension cable. These components provide electrode inputs that are closer to the source of the signal during electromyographic (EMG) testing. The intent of this design is to reduce signal noise during procedures requiring high-impedance electrodes. The proposed device is for use with the Cadwell Excel (K880088A) EMG instrument.

All device components are reusable and supplied non-sterile. The extension cable with electrode input box is compatible with EtO sterilization guidelines for procedures requiring a sterile field. The input box is available with separate active and reference input connectors or a single phono jack connector.

The attached extension cable connects the input box to the preamplifier by way of a cable adapter. The existing preamplifier will be fitted with three pin DIN connectors to accept the cable adapter.

## 1. Submitter Name and Identification

Cadwell Laboratories, Inc.
909 North Kellogg Street
Kennewick, WA 99336
[phone]
Contact: Chris Bolkan
Establishment Registration Number: 3020018

## 2. Proposed Device Name and Part Number

Trade Name (Proprietary Name): Cadwell Excel and Cadwell Excel Plus

| Proposed Device | Order Number |
| --- | --- |
| Four-Channel Preamplifier
OR | 199085-200 |
| Eight-Channel Preamplifier | 199088-200 |
| Buffered Input Box with Extension Cable | 197112-200 |
| Cable Adapter | 199155-200 |

Common Name or Usual Name: Electromyography and Evoked Potential Equipment.

Classification: Type II

| Name | Number |
| --- | --- |
| Electromyograph | 84GWP |
| Electromyograph, Diagnostic | 89IKN |

{1}

2

# 3. Identification of the Substantially Equivalent Device

**Reason for Premarket Notification:** Modification to an existing device.

**Modification of Existing Device:** The proposed device is a modification to the existing Cadwell Excel (K880088A) device. The Cadwell four-/eight-channel preamplifier with buffered input box allows electrode inputs to be made closer to the signal source for reduced noise during procedures requiring high-impedance electrodes. The proposed device complies with the same safety standards as the existing device.

## Safety of the Cadwell Excel (K880088A) Device

The original device complies with the following safety standards for medical equipment:

- IEC 601-1 Medical Electrical Equipment. Part 1. General requirements for safety. Type: Class 1 or grounded equipment, continuous operation, with B and BF applied parts.
- IEC 878 (1988) Graphic symbols for electrical equipment in medical practice.
- NFPA 99. Standard for Health Care Facilities.

The original device complies with the following general safety standards for electrical equipment:

- ANSI/NFPA No. 70 (1990) National electric code.
- UL 796 Standard for printed wiring boards.
- UL 94 Standard for tests for flammability of plastic materials for parts in devices and appliances.

## Safety of the Cadwell Excel (K880088A) Four-/Eight-Channel Preamplifier Device

The original device complies with the following standards:

- IEC 601-1 isolated applied part Type BF.
- American Electroencephalographic Society Guidelines for Clinical Evoked Potential Studies, 1984. Section III. Standards for Clinical Evoked Potential Equipment: Minimal Standards, Amplifier Averager. Section IV. Standards for Clinical Evoked Potential Recording: Calibration.

{2}

Effectiveness of the Cadwell Excel (880088A) Device

The original device is designed to perform the measurements needed for electromyography (EMG), nerve conduction velocity (NCV, F wave, and H reflex), evoked potentials (brainstem, visual, somatosensory) and repetitive nerve stimulation. The effectiveness of these clinical protocols is described in standard medical school textbooks. Please refer to the following texts for additional information.

Aminoff MJ: Electrodiagnosis in Clinical Neurology, Churchill Livingstone Inc., 1980.

Chiappa KH: Evoked Potentials in Clinical Medicine, ed 2. Raven Press, 1990.

Delisa JA: Manual of Nerve Conduction Velocity and Somatosensory Evoked Potentials, ed 2. Raven Press, 1987.

Johnson EW: Practical Electromyography, ed 2, Williams & Wilkins, 1988.

Kimura J: Electrodiagnosis in Diseases of Nerve and Muscle: Principles and Practice, ed 2. A Davis Company, 1989.

Spehlmann R: Evoked Potential Primer: Visual, Auditory, and Somatosensory Evoked Potentials in Clinical Diagnosis, Butterworth Publishers, 1985.

Regan D: Human Brain Electrophysiology: Evoked Potentials and Evoked Magnetic Fields in Science and Medicine. Elsevier Science Publishing Co., Inc., 1989.

4. Description of the Proposed Device

The extension cable with buffered electrode input box allows electrode inputs to be made closer to the source of the signal for reduced signal noise during procedures requiring high-impedance electrodes. The electrode input box is available with separate active (labeled •) and reference connectors or a single phono jack connector to accommodate recording electrodes with these connector types.

The input box is enclosed in a white polyethylene foam sheath. The sheath houses a circuit board consisting of a buffer circuit, two electrostatic discharge (ESD) networks (one on each side of the buffer circuit), and a separate circuit designed to limit fault currents.

3

{3}

The circuit board is attached to a polyvinyl chloride extension cable terminated in an eight-pin DIN connector. The input box and extension cable are connected to the preamplifier by way of a polyvinyl chloride cable adapter terminated in a three-pin DIN connector. The adapter cable does not qualify as a class II device.

## 5. Statement of Intended Use

The general purpose of the proposed device is identical to the predicate device: "to perform the measurements needed for electromyography (EMG), nerve conduction velocity (NCV, F wave, and H reflex), and evoked potentials (brainstem, visual, and somatosensory), and repetitive nerve stimulation." The purpose of the proposed device is to allow compatibility with high-impedance electrodes. The design of the device provides inputs that can be made closer to the source of the signal for reduced signal noise during procedures requiring high-impedance electrodes.

## Duration of Use

The four-/eight-channel preamplifier with buffered input box is designed for use during the duration of the procedure only. This device is not for chronic use and is labeled accordingly.

## Intended Use Environment

Use of the proposed device is to be administered under the direction of a trained physician, surgeon, neurologist, or electrophysiologist in a suitable operating room or clinic.

{4}

5
# 6. Comparison of Device Technological Characteristics

The proposed device is a modification to the preamplifier of the Cadwell Excel (K880088A) device. Physical modifications to the predicate device are in the following areas:

1. The recording component (electrode input box) from the existing preamplifier is placed at the end of the extension cable. The proposed device provides closer electrode inputs for reduced signal noise during procedures requiring high-impedance electrodes.

2. The proposed input box and extension cable are compatible with EtO sterilization requirements.

3. To accommodate the proposed input box and extension cable, the existing preamplifier requires a hardware upgrade from the existing five-pin DIN connector to a three-pin DIN connector. The proposed device also requires a preamplifier cable adapter. The cable adapter does not qualify as a class II device.

The proposed device and the predicate device have nearly identical technical specifications and characteristics. The modification consists of adding a remote electrode input box for use with a single, high-impedance electrode. The input box connects to the existing preamplifier by way of an extension cable and cable adapter. The cable adapter requires a three-pin DIN connector in place of the standard five-pin DIN connector currently on the preamplifier.

{5}

| Criteria | Cadwell Excel with the existing four-/eight-channel preamplifier | Cadwell Excel with the proposed four-/eight-channel preamplifier and buffered input box |
| --- | --- | --- |
| **Safety** | Designed to comply with requirements of UL 2601-1, CSA C22.2 No. 601.1-M90, and IEC 601-1. Type BF. | Designed to comply with requirements of UL 2601-1, CSA C22.2 No. 601.1-M90, and IEC 601-1. Type BF. |
| **Electrode inputs** | 20 buffered electrode inputs with built-in full montage selection or 5-pin DIN connector. | • 20 buffered electrode inputs with built-in full montage selection.
• One remote buffered electrode input with separate active and reference pin jack connectors or single phono jack connector.
Preamplifier fitted with 3-pin DIN connector. |
| **Isolation mode rejection** | > 110 dB. | > 110 dB. |
| **Sensitivities** | 2 micro V/div to 25 mV/div in 13 steps. | 2 micro volts/div to 25 mV/div in 13 steps. |
| **Noise** | 0.6 micro volts RMS (3 micro V peak to peak) from 10 Hz to 2 kHz typical. | 0.6 micro volts RMS (3 micro volts peak to peak) from 10 Hz to 2 kHz typical. |
| **Input impedance** | > 10,000 Mohms | > 10,000 Mohms |
| **Impedance measurement** | Built-in individual electrode impedance measurement, including ground. | Built-in individual electrode impedance measurement, including ground. |
| **Calibration** | Built-in calibration signal 10 micro V to 50 mV peak to peak, sine or square wave in 13 steps. | Built-in calibration signal 10 micro V to 50 mV peak to peak, sine or square wave in 13 steps. |
| **Artifact suppression** | Automatic or manual stimulus artifact suppression. | Automatic or manual stimulus artifact suppression. |
| **Low-cut filters** | 2-pole filter. Selectable at 0.04, 0.1, 1, 3, 10, 30, 100, 500 Hz. | 2-pole filter. Selectable at 0.04, 0.1, 1, 3, 10, 30, 100, 500 Hz. |
| **High-cut filters** | Two-channel mode: 2 pole Butterworth--100, 200, 500 Hz; 1, 2, 3, 10, 20 kHz. Four- and eight-channel mode: 2 pole Butterworth--70, 100, 200, 500 Hz; 1, 2, 3, 5 Khz. | Two-channel mode: 2 pole Butterworth--100, 200, 500 Hz; 1, 2, 3, 10, 20 kHz. Four- and eight-channel mode: 2 pole Butterworth--70, 100, 200, 500 Hz; 1, 2, 3, 5 Khz. |

{6}

7

# Testing and Validation

The proposed device underwent engineering and clinical testing to validate that the device functions as a remote buffer preamplifier when used with the appropriate electrodiagnostic device. For validation procedures and results, please see Enclosure 3 of the previous submission dated October 16, 1996.

# Conclusion

The results of engineering tests 1 and 2 indicate that the input impedance is greater than 10 Mohms when the active and reference connectors are subjected to ten strikes of 8-kV ESD each.

The following tests were carried out with the proposed device connected to the intended electrodiagnostic instrument. The results from test 3 show that the gain is not affected by passing the signal through the proposed device. The results of test 4 show that the patient auxiliary current is well below the regulatory limits set forth by IEC 601-1 for BF connections. The results of test 5 show that the measured value of peak-to-peak noise is less than the allowed valued.

Clinical results from test 6 show that the proposed device does not distort the morphology of the nerve conduction waveform, nor does it significantly affect the onset time, peak time, or amplitude when compared to the signal that does not pass through the proposed device. Additional clinical results in test 7 indicate that the proposed device does not distort the morphology of the EMG waveform when compared to the signal that does not pass through the proposed device.