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A New Approach to �
Return Electrodes for Electrosurgery
11506 So. State StreetDraper, Utah 84020
Phone: (801) 576-9669Fax: (801) 576-9698
E-mail: [email protected]
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