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Neurosurg Rev (2006) 29: 93–96
DOI 10.1007/s10143-005-0012-6
REVIEW
Ketan R. Bulsara
.
Sunny Sukhla
.
Shahid M. Nimjee
History of bipolar coagulation
Received: 13 July 2005 / Revised: 25 August 2005 / Accepted: 28 August 2005 / Published online: 16 March 2006
# Springer-Verlag 2006
Abstract Bipolar coagulation heralded an age of improved
hemostasis for microneurosurgery. This, coupled with an
improved understanding of microsurgical anatomy, has al-
lowed access to areas of the brain once considered inac-
cessible. In this review, we trace the history of bipolar
coagulation
.
Keywords Bipolar cautery
.
Hemostasis
.
Microsurgery
Background
Maintaining hemostasis during neurosurgical procedures is
critical to favorable outcomes in the operating room. The
fundamental process of electrocauterization utilizes heat
generated from an electrical current that flows through a
metal probe to locally burn or destroy tissue, thereby pre-
venting bleeding. The use of heat-mediated hemostasis is
not a novel concept. In fact, the use of thermal cautery dates
as far back as 3000 B.C., when tools heated in fire were
used to reduce hemorrhage in accidental injuries [ 14].
Historically, boiled oil was initially used to achieve
hemostasis. The oil helped achieve hemostasis in the areas
in which it was employed during an operating procedure,
cauterizing the tissues to which it was applied. The result-
ing charred mass eventually sloughed away [11]. However,
this method fell out of favor because it charred adjacent
living tissue due to its large release of energy.
In 1926, Dr. Harvey Cushing worked with a physicist
named Dr. William T. Bovie, after whom the current elec-
trocautery instruments are named. Dr. Bovie was at The
Cancer Commission at Harvard University. They collabo-
rated to develop a more efficient electrocautery system and
synchronized circuits and electrodes, which became the
mainstay of electrical coagulators in neurosurgery [16]. The
principles and instruments of neurosurgery established in
the late 19th and early 20th century by Dr. Cushing have
largely remained consistent today. Dr. Cushing’s pursuance
of electrocautery stemmed from his guiding principle of
avoiding of injury to the brain by careful and gentle ma-
nipulation of the tissue and by maintaining hemostasis
throughout surgical procedures. This credo echoed that of
his mentor, William Halstead, largely recognized as the
father of surgery in the Western Hemisphere [9, 12, 16].
On October 1, 1926, Dr. Cushing completed his first re-
moval of a brain tumor using electrocautery [15]. At the
inception of the use of diathermy by Dr. Cushing, an amus-
ing event took place. Hugh Cairns, Dr. Cushing’s assistant
at the time, inhaled the smell of the tissue undergoing elec-
trocautery and subsequently fainted [5, 15]. In his post-
operative note, Dr. Cushing described the success of the
operation,
...Then with Dr. Bovie’s help I proceeded to take off
most satisfactorily the remaining portion of tumor
with practically none of the bleeding which was oc-
casioned in the preceding operation. The loop acted
perfectly and blood stilling was almost complete...[15]
Discussion
A common problem encountered by neurosurgeons in
utilizing electrocautery was the fact that, when heat was
applied, it was done so externally to the site where
coagulation was needed. In order to improve the existing
technology, Dr. William L. Clark, a gener al surgeon from
Philadelphia, designed an ele ctrosurgical to ol that provided
K. R. Bulsara (*)
.
S. Sukhla
Division of Neurosurgery, University of Missouri-Columbia,
Columbia, MO 65211, USA
e-mail: ketan.bulsara@hotmail.com
S. M. Nimjee
Duke University Medical Center,
Durham, NC, USA
an important “spark.” The devic e had a motor-driven rotating
disk that acted as a static generator with a spark gap. In
addition to the static generator , a Leyden jar served as a
capacitor , and a resonating coil was also used [16]. Dr. Clark
then realized that, when the device was attached to a current
and applied to a tumor, it destroyed the cells by desiccation.
These results illustrated that cancer cells were more
vulnerable to heat than normal body cells. The heat produced
by the coagulation and desicc ation killed th e malignant cells,
thereby exposing blemishes in the actual tumor .
The mechanism by which bipolar coagulation works is
diathermy. Very high frequency of applied alternating cur-
rent causes motion of water molecules that then generates
the heat. Cutting currents are comprised of sine waves, while
coagulating currents contain jagged waves.
In monopolar cutting, an electric current at a high volt-
age is channeled to a fine tipped electrode, with the patient
serving as a ground via a ground plate. The current is di-
rected as a single point, and later branches out into the
surrounding tissues that are present. This branching limits
the utility of monopolar cautery as it cannot come into
contact with bone or metal and will not work in wet fields.
There is a significant amount of current and heat generated
from 1−2 cm away from the contact site which can cause
additional damage to the surrounding anatomy of the sur-
gical site. Bipolar cautery was developed in order to mini-
mize the non-specific activity of monopolar cautery and led
to more specific and controlled cauterization of tissue.
In 1940 bipolar cautery was pioneered by Dr. James
Greenwood, chief of the neurosurgical service at The
Methodist Hospital in Houston. At the time that bipolar
coagulation was invented, Baylor College of Medicine
was in Houston, not Dallas. Dr Greenwood introduced the
concept of two-point coagulation into the field of
neurosurgery. James Greenwood was aided in the devel-
opment of bipolar cautery by being gifted in the
electronics of his time. He was an amateur short-wave
radio operator. In his initial observations about electro-
cautery in neurosurgery, Greenwood stated that a strong
current maintained hemostasis of vessels in the scalp,
dura, or brain, but produced damage to the surrounding
tissue, with slight carbonization, necrosis, and later tissue
reaction [6]. He also mentioned how it was undesirable for
current to pass through vessels, since they would coagulate
and subsequently shrink beyond the field of vision, even
before the complete hemostasis occurred. This led
Greenwood to replace the conventional ball-type electrode
with fine-tipped forceps, which were attached to a current-
generating power source. “In order to use the instrument,
vessels must be picked up so that the vessel actually lies
between the tips,” Greenwood concluded [6]. He also
noted that the instrument was of exceptional value when
the neurosurgeon was involved in cortical dissection as
well as in the dura. The replacement of the ball-type
electrode with the forceps also facilitated fine manipula-
tion of the tissues and vessels in order to apply the current
in a specific and efficient manner [6]. In one instance,
Greenwood connected the bipolar forceps to the mono-
polar coagulating machine, and this led to only one side of
the bipolar forceps being active, which still provided
sufficient current to induce hemostasis during a neuro-
surgical procedure [17].
Dr. Greenwood modified his bipolar device, making one
of the two forceps blades hollow and attaching suction to
it. This “bipolar suction” allowed him to achieve the first
series of complete removals of intramedullary ependymo-
mas, with excellent results. The Greenwood bipolar-suction
device is still available and useful for lesions such as
acoustic neuromas and intramedullary gliomas.
A critical modification of the two-point coagulation sys-
tem, by Dr. Leonard Malis, led to the development of
bipolar cautery as it is used today. Dr. Malis trained in
neurosurgery at Mount Sinai in New York and completed
physiological research in Dr. John Fulton’s laboratory at
Yale University. He subsequently became the Chairman of
Neurosurgery at Mount Sinai. Dr. Malis designed and built
the first commercial bipolar coagulator in 1955 [11]. Malis
later carried out the first microneurosurgical operation in
1965 and designed the first practical course on microneu-
rosurgery in the United States of America in 1969. Jerry
Malis, Dr. Malis’s brother and a physiologist, designed the
Malis CMC-II solid-state unit. Figure 1 shows a Malis
bipolar device that is currently available.
The bipolar system, first developed by Malis, uses a
1 MHz waveform for cutting and coagulation. A benefit of
bipolar cautery is that it does not require a grounding pad
as is required in monopolar cautery. The energy at the tips
is separate, so the current passes only between the two tips
of the instrument, eliminating the heat and current
spreading to the surrounding area. If the actual tips of
the bipolar forceps come into contact with each other
without a vessel passing between the tips, coagulation does
not occur. A majority of monopolar systems use 2,500 V,
while a bipolar system uses only 140 V [ 7]. Thus, bipolar
cautery requires only a fraction of the actual power that a
monopolar system uses. In fact, if a monopolar cautery
system is set to the same level as that of a bipolar system,
the power level is insufficient for operational use.
Fig. 1 A commercially available Malis bipolar system
94
Bipolar cautery has been noted to be far superior to
monopolar coagulation. A laboratory comparison between
bipolar and unipolar coagulation demonstrates the differ-
ence in efficiency between to the two systems. In a study
done on one side of a rat brain, several surface vessels can
be sealed with the monopolar system at the lowest possible
power setting; on the other side of the brain, stroking with
bipolar forceps set at the lowest bipolar coagulating power
can coagulate all the surface vessels. After Evans’ blue dye
is injected, it is clear that, in comparison to the bipolar
system, the monopolar system causes excessive damage
that extends deep into the brain, the result of deliberate
destruction of the entire cortical vascular supply [11]. Sup-
portive findings in experiments conducted on rats showed
that damage from the unipolar system was far greater than
that from the bipolar system [11].
In addition to maintaining hemostasis, bipolar cutting
current may also be used for the removal of tumors. Sharp
forceps may be used to make almost parallel orange-slice
type cuts and then take out the segments. Another method
utilizes a loop attachment on the tips of the forceps. As the
paired loop tips are brought together in the tissue, the cut-
ting current removes neat cylindrical cores of the tumor,
thus permitting virtually bloodless decompression. For a
soft acoustic neuroma, a setting of 45 Malis units is suf-
ficient for tumor excoriation, and this level may be in-
creased to 50 Malis units in regions of the neuroma that
are more fibrotic. Most meningiomas require a setting of
60 Malis units, and, for densely fibrous meningiomas, a
setting of 70 is used. Calcified craniopharyngiomas can
be cut well, and fragment at 40 to 45 Malis units [11].
Neurovascular surgery with bipolar cauterization on middle
meningeal, superficial temporal, or occipital arteries are
easily closed with the use of a bipolar cautery [17].
While bipolar forceps have provided significant pro-
cedural advances in neurosurgery and reduced morbidity
during procedures, there are minor drawbacks to the tech-
nology. Sticking and charring are procedural problems
that affect traditional bipolar forceps. In most cases,
neurosurgeons are used to pausing while they are
performing a procedure, in some cases just to avoid
overheating or to pass the instrument to a surgical
technologist to be cleaned. In certai n situations the
forceps generate a significant amount of heat while
coagulation is being performed. This causes them to
adhere to and even tear blood vessels and tissue with
which it comes into contact during the procedure. Another
dilemma faced by neurosurgeons is that, when they pass
off their instruments, they must reposition themselves as
well as reorient their instruments to the site they are
actually working on. In 1966 the bipolar coagulator cost
$120; these days it may cost as much as a few thousand
dollars. Local heat is generated and causes tissue burns and
clot formation which adhere to the tips of forceps. Thus, it is
important to help irrigate the site where a neurosurgeon
intends to coagulate, since this prevents the adherence of
the tips of the forceps. A very important adaptation, by Dr.
Manuel Dujovny and his team in 1975, was the use of
automatic simultaneous irrigation [5]. The major advan-
tages included adjustable fluid pressure and the presence
of constant irrigation, and it also eliminated the need for
an associate to help irrigate the site [4]. Other minor
improvements included scratch pads and scalpels that were
used to clean forceps that had accumulated charred blood
and tissue, which hindered the coagulation process.
Another novel advancement was insulating forceps,
which limited the actual charring of tissues and limited
adjacent damage. A thermistor-regulated bipolar forceps
was later introduced by Sugita and Tsugane, but, although it
minimized local overheating or sparking, irrigation was still
necessary [5]. Greenwood and, later, T.B. Scarf developed
suction irrigation forceps; however, their use was compli-
cated by the fact that irrigation was not easily controlled [4].
Later, a continuous saline drip irrigation system was in-
vented by T.T. King and R. Worpole, but it was undesirable
because (a) it was difficult to regulate the amount of ir-
rigation required during coagulation and (b) it provided
continuous flow even if the bipolar cautery was not being
used [5]. Other solutions that have been used to irrigate the
Table 1 The advantages of bipolar tissue management (adapted
from http://www.dentalexplorations.com/articles/23.html)
Advantages of bipolar tissue management
Less tissue dehydration, carbonization and further tissue reaction
Permits the control of hemorrhage
May be used on patients with pacemakers, and with defibrillators
Permits planning of soft tissue, a procedure unique to bipolar
electrosurgery
Provides a clear and improved view of the operative site
Increases the efficiency of the operation
Reduces chair time for each operation
There is no shrinking of the blood vessels being coagulated
Reduces fatigue of the surgeon
No shrinkage of the dura when a vessel is coagulated
Cuts and coagulates in irrigated, minimal blood, or dry fields
No grounding pads are needed
Coagulation is possible under saline and other fluids
May be able to control actual current being used
No tissue charring seen
Risk of thrombosis is minimized
Minimal damage being produced in coagulation since current flows
only between the forceps’ tips
Distinct circuitry and waveforms
Current is not carried along a blood vessel into deeper tissues
Voltage used may be kept constant throughout the procedure
Can handle vessels in certain areas where monopolar cautery may
not be possible
Cuts and coagulates at energy levels that are a fraction of those
required for monopolar electrosurgery
Eliminates heat and current spread to surrounding tissues
Cost efficient, very good results, and relatively safe
95
site of coagulation are physiological saline and artificial
cerebrospinal fluid. The use of mannitol is beneficial in
limiting the adherence of coagulated tissue and clots, and it
keeps the tissues cool at the same time.
The most important benefit seen in the use of bipolar
cautery is that the length of surgery is markedly decreased
and there is a significant reduction in intraoperative blood
loss. There is also a smaller portion of the tissue in the elec-
trical field and decreased heat production, which decreases
tissue damage. Finally, an important but overlooked fact
is that the forceps used in bipolar cautery facilitate gentle
and precise manipulation of the tissue. Bipolar cautery for-
ceps are available in many different lengths, which helps
surgeons to adjust to coagulating vessels, such as longer
forceps for use deeper in the cranium. Typically, six grad-
uations are found that are indicative of the current intensity.
A graduation of 1 may be best used on vessels 0.05−0.5 mm
in size; graduation 2 for vessels 0.5−1.0 mm, and grad-
uation 3 for vessels1.5−2.5 mm [17]. In addition, a great
improvement encountered in bipolar cautery was the use of
titanium forceps, because of their ability to remain cool on
the exterior and since tissues did not attach to the forceps.
The advantages of bipolar tissue management are shown
in Table 1.
In recent years many other surgical specialties have also
incorporated the use of bipolar cautery. In obstetrics and
gynecology, cauterization may help arrest excessive bleed-
ing that occurs during surgical procedures or that is related
to bleeding in the female genital tract [2]. Also, in general
surgery, bipolar cautery plays an important role in the
treatment of hemorrhoids, when there is a great deal of
bleeding [10]. Through the pioneering work of bipolar
cautery by Dr. James Greenwood and Dr. Leonard Malis,
neurosurgeons have seen improved outcomes in their sur-
gical procedures. These intraoperative improvements have
also extended to post-surgical benefits, as patients do not
require blood transfusions as was needed in earlier cases,
and there is also a reduced incidence of infection from
focused hemostasis of bipolar cautery compared to pre-
vious techniques [8]. Further modifications by pioneers
such as Drs. Yasargil, Fukushima and Spetzler have facil-
itated its use in microneurosurgery and deep-seated brain
tumors [1, 3, 13].
Summary
Bipolar cautery is a significant invention in the field of
neurosurgery. It was designed to deal with the complica-
tions that resulted from the available devices of the time,
and, moreover, it responds to the key principle of gentle
tissue management espoused by Halsted and Cushing [12].
The development of bipolar cautery represents a classic
paradigm of scientists from a variety of disciplines working
together towards improving therapy that has had a direct
impact on procedural outcomes, not only in neurological
surgery but also in other surgical subspecialties.
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Comment
David Rojas-Zalazar, Jorge Mura, Evandro de Oliveira, São Paulo,
Brazil
Bulsara et al. present an interesting review about the “History of
bipolar coagulation”. Starting with the electrocautery used by
Professor Cushing to remove a brain tumor in 1926, today, a modern
operating room for any neurosurgical procedure is not conceived
without available bipolar coagulation. This article shows how
modern microvascular and tumoral neurosurgery is possible because
of the advantages of using diathermy coagulation. This 50-year-old
tool is as important as the operative microscope, modern neuro-
anesthesia and the evolution of neuroimaging for current state-of-the-
art microneurosurgery. Professor Yasargil and others mastered the
use of modern bipolar coagulation not only to maintaining hemo-
stasis; the bipolar forceps can be used as well for gentle dissection of
the neural structures or for the remodeling of the aneurysm neck for
proper clipping, among many other useful microsurgical technical
applications. This is an interesting historical review of this milestone
device of the neurological surgery operating room and it must be read
by residents and young neurosurgeons.
96
