1) Laparoscopic surgery has become popular as it reduces post-operative pain and recovery time compared to open surgery. However, establishing an insufflated abdominal cavity safely and maintaining adequate visualization during procedures has posed challenges. 2) Over time, medical device companies have developed high-flow insufflators, specialized gas filters, and disposable tubing to optimize pneumoperitoneum and address issues like gas leakage, fluid backflow, and smoke evacuation during increasingly complex endoscopic procedures. 3) Advances in membrane technology have led to hydrophobic gas filters that allow high gas flow until wetted, at which point they block fluids and aerosols from entering insufflators and compromising equipment or

1. Industry News Page 10f5
NBS Group Supply
(Medical Device Division)
Manufacturers & Consultants for the Medical Products Industry
Industry News
Can Surgery Be Made Safer?
By: Charles E Meisch
Endoscopic consultant
NBS Group Supply (Medical Device Division).
257 Livingston Avenue
New Brunswick, NJ 08901
1-888-800-8192
Surgery is the branch of medicine dealing with manual operative procedures for the correction of
deformities, defects, injuries, and the diagnosis of certain diseases. Traditionally, these procedures
required open surgery known as a laparotomy. Within the last few years Minimally Invasive Surgery,
specifically Laparoscopy which deals with the abdomen, has become a replacement for many open
procedures.
Studies have shown major benefits to the patient in terms of reduced post operative pain, increased post
operative comfort, reduced hospital stay, quicker return to normal physical activities and ultimately a
quicker return to work. Improved comes is and reduced wound complications associated with large scars
are also major advantages associated with this technique.
Many of the general procedures are performed using a rigid scope that is placed into the abdominal
cavity with the use of small trocars. A mini scope can be inserted allowing direct visual observation. This
allows the placement of additional trocars that enable the insertion of micro instruments for the repair,
removal, or diagnosis of problems without the need for large surgical cutting of the abdomen.
What is taparoscopy?
Laparoscopy is abdominal exploration using a type of Endoscope called a Laparoscope. Laparoscopy is
a technique which permits the examination and surgical treatment of viscera and organs within the
peritoneal cavity. It is becoming popular, rapidly replacing many procedures that traditionally required
open laparotomy.
To improve visualization of the peritoneal cavity and facilitate instrument manipulation during
laparoscopy, the abdominal cavity must first be filled with an insufflating gas producing a
pneumoperitoneum. Laproscopic insufflators are specialized pressure-limiting gas flow regulators that
make it easy to establish and maintain a pneumoperitoneum. To establish the pneumoperitoneum, one
end of a piece of low pressure tube ranging in length from approximately 8 to 10 feet is connected to the
insufflator outlet port. The other end of the tube is connected to an Insufflation needle know as a Veress
needle. A Laproscopic procedure usually begins with the insertion of the Veress needle into the inferior
portion of the umbilicus, since this region of the abdominal wall is usually devoid of major blood vessels
and nerves. Furthermore, inter-abdominal structures usually do not adhere to the region of the
abdominal wall except in patients who have previously undergone surgery.
Three liters of gas is usually sufficient to produce a space in the peritoneum cavity to allow for adequate
visibility. The exact amount of gas used to establish a pneumoperitoneum depends on the size of the
abdominal cavity, development of abdominal musculature elasticity of the abdominal wall, as well as the
degree of gas leakage and rate of reabsorbing.
Once the pneumoperitoneum is established, the veress needle is removed from the peritoneal cavity.
Then a trocar in a sleeve is used to enlarge the needle puncture. After completely penetrating the
abdominal wall, the trocar is removed, followed by insertion of the Laparoscope. This is done through
the trocar sleeve. Additional trocar punctures are often needed to allow a number of instruments to be
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used in the peritoneum cavity without removing the Laparoscope. Upon completion of the procedure,
most of the Insuffiation gas is expelled manually depressing the abdominal wall through an existing
trocar sleeve. The body innocuously absorbs any gas remaining in the abdomen.
Blind insertion of Insufflation with a Veress needle can cause serious complications. If the Veress needle
was accidentally inserted into a blood vessel, Insufflation could cause the formation of a gas embolism.
The introduction of gas through a Veress needle that has not completely penetrated the abdominal wall
could also produce a subcutaneous or subfascial emphysea. Moreover, the insertion of any sharp object
into the abdomen can perforate the section of the bowel that is adhered to the peritoneum possibly
causing peritonitis.
Filling the abdomen with gas after visually confirming safe interperitoneal placement Significantly
reduces the number of complications associated with the Veress needle. Rather than use a Veress
needle to insufflate the peritoneal cavity, some surgeons prefer to puncture the abdominal wall with a
trocar for creation of the pneumoperitoneum. Once the trocar has penetrated the abdominal wall, the
Laparoscope can be immediately inserted through the trocar sleeve to insure proper interperitoneal
placement. As a result this procedure enables the surgeon to reduce the number of blind insertions
using a Veress needle and trocar to one trocar only.
Twenty years ago the concept of this procedure would never even have been considered. Almost
anything we use or rely on has changed, most have evolved. The same thing has happened in the
medical device industry. Some medical procedures performed today were not thought possible then.
The introduction of Endoscopic surgery also involved the use of scopes to help doctors see areas they
didn't have access to in the past. Endoscopic surgery started in the Gynecological area and moved
quickly into the Urological area. The use of rigid telescopes to see areas that normally would require
open surgery reduced costs and lowered infection rates. After several years, general surgeons started to
become interested in these newer techniques using rigid endoscopes. In the early 1980s, general
surgeons started to use endoscopes for purposes other than diagnosis. They called upon the
manufacturers to develop more sophisticated equipment that could reach further into areas than anyone
could realize. These new smaller Endoscopes were necessary. Everything was being downsized or
being made smaller so that they could reach areas that were harder to reach without open surgery.
Surgeons then began to realize that these instruments were not only useful for diagnosis but could also
be used immediately to resolve certain problems. After the late 1980's, Endoscopes and Endoscopic
procedures became the norm rather than the exception. Companies evolved to try to solve and
supplement the lack of supply.
The difference between the United States and Europe was the accessories. The US wanted as many
disposable accessories as possible while Europe did not see the need to dispose of the accessories due
to costs. In the US, the market for insuffiators and accessories continued to increase.
For instance, colecystectomy procedures are estimated to be 800,000 per year; Myomectomy 125,000
procedures per year; appendectomy 115,000 per year; Nissen Fundoldoplication 100,000 per year.
Other procedures are now being preformed such as, bowel resection, hysterectomy, bladder
suspension, endometriosis, splenectomy, and adrenaletomy along with gastric bypasses and many
more. These procedures can now be done endoscopically.
The primary concern for all manufacturers was the creation of smoke generated by electronic knives or
lasers in the pneumoperitoneum (see figure 1).
As laproscopic procedures evolve and become more complicated,
the original insuffiators could only produce 9.9 liters per minute. All
used C02 gas which is relatively inert is easily absorbed into the
body. Newer units were made to increase the flow, but not the
pressure.
Original insufflators used silicone tubing (generally one-quarter
inch 1.0.) that flowed from the insufflator, through the tube and into
the patient. Recently, within the last 10 years, it became obvious
that putting a foreign gas into the body should be filtered and any
bodily fluid that could accidentally be pushed up through the tube
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should be stopped prior to going into the insufflator. Once into the F,0g re 1
insufflator, it becomes very difficult to cfean and recondition these I U
very expensive units. Most Endoscopic companies who sell insufflators now offer them with disposable
tubing containing filters. The filters are usually rated at .1 micron but can be anywhere from .1 to .3
microns and they are all suppose to be hydrophobic.
The 9.9 liters per minute insufflators were sufficient when using an ordinary gas filter, and inserting it into
the line allowing it to filter the gas and also stop any backflow of fluid from getting into the insufflator. As
procedures increase in complexity, insufflators were made capable of delivering increased liters per min
of gas. This was necessary due to longer procedures, and the use of multiple trocars.
The most common problem is finding a filter that can perform to flow rates upward of 40 liters per
minute.
This is a very high flow from the original 9.9 units. Insufflators work differently. They do not just allow gas
to flow from a machine to a patient. They are critical in nature. They allow the gas to cycle approximately
every 1.8 to 2 seconds at relatively high pressure against the filter and there are mechanisms in the
insufflators that sense the backpressure of the abdomen. Once set, the backpressure will stop the
insufflation process until it senses the need to re-inflate.
The false reading on an insufflator due to the lack of flow caused by the filter, the blocking of the filter, or
other obstacle in the pathway may not allow for an accurate pneumoperitoneum to be achieved, or
maintained.
When using low flow insufflators (by low flow 9.9 UM to 15 UM), most people bought standard off the
shelf gas filters.
They seemed to work fine, however once you get up into the 20,
30 or 40 UM range, specialized filters needed to be develop. Not
all companies have pursued this. Some have and developed
unique filters (see Figure 2). As the gas cycles, it does not directly
hit a flat filter membrane (flat meaning the filter housing itself is flat
in nature encompassing the membrane). After careful testing, it
was determined that a baffle system was necessary to allow large
cycles of gas enough time to get through the filter and not cause
excessive back pressure which would prematurely shut off the
insufflator. The baffled or bulbous shaped back of the filter allows
a reservoir of gas to build up and then migrate through the filter
membrane prior to the next cycfe. Without this, the cycles create Figure 2
excessive back pressure. This can cause problems with the
operation of the equipment and false shut downs along with overpressure alarms.
Membranes themselves have also evolved. Filter companies have been working on gas filters that are
hydrophobic both in the respiratory and in the Insufflation area for some time. Filters are available that
produce the optimum amount of flow at the least amount of cost. Using a flat filter on a high flow
insufflator at 1.8 to 2 cycfes per second can damage and most likely never let the gas pass through the
filter or achieve the rated filter micron size?
The only way to do this is to allow the gas to enter the buffered area that was developed (See figure 1).
Any filter that is used should carry an ULPA or HEPA rating. Any filter manufacturer that will not supply
you with the test data to prove this should not be used.
Insufflators have also evolved from the 9.9 UM to 30 UM or even higher flow rates.
They all function in a similar nature and contain sophisticated
electronic feedback devices. Once set, these new high flow units
will fill the peritoneum to the appropriate pressure and maintain it
as the body absorbs some of the gas. Trocars may also leak
some gas (see figure 3). Aside from the geometry of the filter itself
testing will cfearly show that trying to push a high flow of gas
through a 1/4 inch hole with no reservoir becomes virtually
impossible. With any unit purchased, a specification sheet with
test criteria proving flow through the filter at the advertised flow
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4. Industry News Page 4 of5
rate should be requested of the manufacturer.
Figure 3
Along with the geometry of the filter housing, filter membranes also evolved. Industry discovered that
aerosol droplets can bypass filters causing malfunction of insufflators. This also increases maintenance,
physically restricts the passage of airflow, and more seriously may lead to bacterial growth in the
insufflator.
During the late 1950's, membrane technology began to expand. Osmotic transfer of salts across the
membrane began in the area of de-salini-zation and has lead into kidney dialysis. A hypothesis was
formed that a membrane could be designed that would pass air but would not pass water and also filter
out aerosols and bacteria from the air stream. This membrane would be an analogous to a child's toy for
making soap bubbles which uses a water film formed in a hoop. When a child blows into the hoop a
pressure differential across the hoop causes the film to bulge out and form a bubble. For more
information on thin films refer to 1: Strength of Materials Part 2 by Timoshenko; or 2:Advanced Strength
of Materials by Denhartog.
Reducing the hoops diameter increases the differential pressure (not force) needed to distort the film,
thereby creating a very fine net the size of the original hoop. With the differential pressure increase the
total force across the net is higher. Another characteristic that must be considered is the hydrophobicity.
Air would be free to move through the net until the net was touched by a liquid which would form a film
blocking the movement of air until the differential pressure across the net was too great or the liquid was
evaporated. Obviously, the net would have to be some material which would cause liquid to form a film
across the intercies. The specific composition of membranes with these properties is generally a trade
secret of the membrane manufacturer. However, the most common material is Teflon. The Teflon sheet
is either mechanically perforated or is stretched to form tears or holes in the material. Other methods are
to coat any netlike substrate with a chemical, generally a silicone compound. The effect of this is to
create a hydrophobic membrane that allows free flow of air until the membrane is wetted. At this point
air-flow would be stopped as long as pressure differential is below the maximum level. Air-flow through
the filter must be maintained by the membrane. The membrane must have sufficient small intercies to
stop or entrap aerosol fluids and microbes. The microbes are generally considered to be carried by the
aerosol fluids. The membrane must be capable of being secured either mechanically or by heat sealing
into the exit area of the filter.
Test results of new membranes were extremely encouraging. They allowed air-flow at a normal rate until
liquid covered one side in which case the filter shut down. This saved the insufflator from being
damaged. The bacteriological testing showed that these membranes stopped pathogens and aerosols
as well as any commercial microbial filters and met HEPA and ULPA criteria.
Surgery was not at a stand still during the development of the new filters and membranes. New surgical
tools were introduced that were micro in size along with both laser and electrical knives. Both of these
tools minimized bleeding by cauterizing while cutting, however they produced dense smoke in the
abdomen.
No one really knew what the smoke consisted of, but most agreed
that it was best kept out of the air. The solution was to develop a
new type of filter that could be connected to an exit port of a trocar
and capture the smoke. Lab tests showed that in the presence of
this dense smoke, filters not designed for smoke elimination could
shut down in 30 seconds. Analysis of the smoke showed it to
contain proteins, peptides, amino acids and other breakdown
particles. In other tests, electron microscopic studies showed a
layer of these breakdown products had formed over the surface of
the membrane blocking airflow. Filter companies have spent a
tremendous amount of time and money to develop an inexpensive G.ourto?sY:.f~~l5:~rpJ.!1t:,,,· _
yet disposable smoke evacuator. A filter that combines fluid
stoppage along with smoke and bacterial filtration to cleanse the Figure 4
expelled gas is now available (see figure 4). It is obvious that this
is needed to control cross contamination and infection and to protect operating personnel from smoke
caused by laser and electro surgery. The designs have been rigorously tested and prove reliable.
(additional information on the devices shown in this article can be obtained by contacting the
manufacturers or the author directly.) In the future, technology will continue to improve. This is just
another stepping stone in the final attempt of surgeons to alleviate discomfort, shorten hospital stays,
curtail cross contamination, and protect operating room personnel.
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5. Industry News Page 5 of5
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