a new approach to return electrodes for · pdf filea new approach to return electrodes for...

A New Approach to �

Return Electrodes for Electrosurgery

11506 So. State StreetDraper, Utah 84020

Phone: (801) 576-9669Fax: (801) 576-9698

E-mail: jisaacson@megadyne.net

James D. Isaacson

MEGADYNE Medical Products, Inc.

Abstract:

A new type of patient return electrode has been developed to safely exit the �

electrosurgical current from the patient and return it to the electrosurgical �

generator. This new type of return electrode is as safe as gel pads with contact

quality monitoring systems (CQM) such as REM ®or ARM tm although this technology

does not use any form of CQM. This new return electrode does not rely on direct

contact with the patient’s skin, like commonly used gel pads. This new technology

obviates the need to shave patients and does not stimulate an adhesive reaction from �

the gel pad’s removal. The reusable nature of this non-contact return electrode also

makes it more economically feasible by reducing costs. The new design avoids direct �

patient contact by taking advantage of capacitive coupling technology.

It is designed to have greater impedance per area than commonly used gel pads. The

greater impedance per area eliminates the possibility of having high current �

densities that could cause an unwanted burn at the return electrode site. As the �

coupling contact area between the pad and the patient decreases, so does the �

current flow thereby limiting the current density. While pad site burns are rare using �

gel pad technology, they can and do occur as a result of excessively high current �

densities at the return electrode site. Although this new return electrode has greater �

impedance per area, the electrosurgical effect is not compromised because the patient �

has a greater contact area than with gel pads. This greater contact area yields an �

overall impedance equal to the impedance between a gel pad and the patient’s skin �

resulting in the same level of efficacy as compared to gel pads. This new patient return

electrode technology is interchangeable with gel pads while providing clinical, �

environmental and cost benefits to the hospital.

A New Approach to Return Electrodes for ElectrosurgeryMEGADYNE'S MEGA 2000 tm Patient Return Electrode System

James D. IsaacsonM.S.M.E. – Massachusetts Institute of Technology

B.S.M.E. – University of Michigan

ARM, is a trademark of ConMed Corp.REM, is a registered trademark of Valleylab, Inc.

A New Approach to Return Electrodes for Electrosurgery

MEGADYNE'S MEGA 2000 tm Patient Return Electrode System

J ≡ Current Density ( mA /cm2 )�I ≡ Current ( mA )�A ≡ Contact Area ( cm2 )J = I/A

Gel Pad

A

As contact area (A) decreases:

I = Constant J Increases

J�I

Burn

As contact area (A) decreases:

I DecreasesJ = Constant

MEGA 2000 tm

Electrosurgical Burns Can Occur When J ≥ 100 mAcm2

JI A

Burn100

mAcm2

100 mAcm2

Single Plate PadSimulated Patient Burn

With Small Contact Area

Monitoring PadNo Patient Burn

Due To CQM

MEGA 2000No Patient Burn

Due to Bulk Resistivity

Well CoupledNormal Use

Diminished EffectDue to Bulk Resistivity�

Little Contact

Light Bulb Dims, Decreased Current