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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_605_Библиотеки_им_академика_М_И_Перельмана.pdf
272 Biomedical Engineering in Gastrointestinal Surgery
Figure 7.2 The difference of tissue trauma induced by an incision (A) or trocar
insertion (B). Once the fibers of the fascia are cut, its original stability can never be
regained again. In opposition, the microscopic structure is practically not altered by
the trocar: As soon as it is withdrawn, the original configuration of the fiber net
is restored. All from MITI.
Table 7.2 The introduction of laparoscopic surgical procedures
1981 Semm Appendectomy
1985 Mu¨he Cholecystectomy
1987 Mouret Cholecystectomy
1990 Pinotti, Shim i Cardiomyotomy
1990 Dallemagne Fundoplication
1991 Wexner Colonic resection
1992 Ablaßmaier Gastric resection
1993 Grundman Whipple’s procedure
Appendectomy: removal of the appendix; cholecystectomy: removal of the gallbladder;
cardiomyotomy: dissection of the muscles of the esophagogastric junction; fundoplication:
reinforcement of the lower esophageal sphincter to prevent reflux; colonic resection: removal of
a part of the large bowel; gastric resection: subtotal/partial or complete removal of the stomach.
7.1 BASICS
Regardless of the procedure, certain basic instruments are always required
in laparoscopic surgery. These include the Veress needle, trocars, telescope, various hand instruments, graspers, and cautery electrodes that can
also irrigate and aspirate and an electronic insufflator as well as the visualization chain.
7.1.1 Pneumoperitoneum
7.1.1.1 Creation of the Necessary Space
Under physiological conditions, there is no space left between the
abdominal wall and the viscerum. Accordingly, sufficient space has to be
created first before a visual exploration and the use of instruments is
considered. To this end, gas is pumped (insufflated) into the abdomen to
273Operative (Surgical) Laparoscopy
establish a so-called pneumoperitoneum. In principle, three different
options are available:
Historically, normal air was used. Air is available everywhere and
is free. One particular drawback, however, is that it causes air embolism
(blockade of the pulmonary arteries) if it accidently enters the venovascular system. Carbon dioxide (CO
) is a better option, since the risk
2
of air embolism is significantly lower and it is chemically inert. Inert gases
like helium or argon would be suitable as well, but they are far too
expensive for routine use. In the past, N
O was used in some centers but
2
is now obsolete because of severe accidents (intraabdominal explosions
after contamination with colonic gas). Currently, CO
insufflation is the
2
most popular technique worldwide.
Since more than 15 years, alternatives to the pneumoperitoneum have
been also on the market. “Gasless laparoscopy” is carried out by elevating
the abdominal wall by means of specially designed hook systems. Thus,
a tent-like space can be created. Due to many specific drawbacks, this
method did not become really popular. Nonetheless, lifting hooks are still
commercially available (
Table 7.3).
In some instances (e.g., preperitoneal hernia repair, retroperitoneal
tumors), artificial space has to be created which is usually accomplished
by balloon dilatators. A large variety of dedicated balloon systems is
available on the market.
Since creation (and maintenance) of an adequate pneumoperitoneum
is decisive for successful and safe laparoscopy, the first challenge now is
how to bring the gas safely into the peritoneal cavity. One option is to
make a tiny surgical incision into the abdominal wall and to introduce
the first trocar under visual control to avoid lesions to the internal organs
(semiopen approach, often also denominated as the “Hasson” approach).
Many surgeons like it since they feel safer, but an incision, of course,
offends against the philosophy of the laparoscopic technique.
Table 7.3 Providing intraabdominal space
Pneumoperitoneum
CO
2
Air
O
N
2
Helium
Gasless laparoscopy
274
Biomedical Engineering in Gastrointestinal Surgery
A more elegant method is the use of the Veress needle which has
been the common technique in laparoscopy since 70 years ago.
7.1.2 The Veress Needle
The needle consists of a sharp outer sheath and a blunt spring-loaded
obturator designed to guard against organ injury upon penetration.
As long as the needle passes through the tissue of the abdominal wall,
the blunt tip of the inner mandrin is pressed into the lumen of the sharp
outer cannula. As soon as the peritoneal cavity is reached, the blunt tip
can move forward and gas is able to flow into the abdomen via the lateral
window. Disposable needles are based on the same design, their advantage
being a sharper tip and visible introduction mechanisms (
The “Veress” principle is imitated still today in many similar applications.
The sophisticated construction of reusable Veress needles gives way
to several causes of malfunction. If the lumen is obstructed by blood or
tissue due to inadequate instrument reprocessing, gas flow will be impaired
or completely blocked. The surgeon could assume, during insertion, that
the peritoneal space has not yet been reached and proceed the needle
mistakenly too deep into the bowel.
The same will occur if a free motion of the internal mandrin is
restrained. This is caused by kinking of the needle or if the space between
mandrin and trocar is soiled.
The potential sources of risk are avoided if disposable Veress needles
are applied. However, the cost factor has to be considered (
Fig. 7.3).
Fig. 7.4).
Figure 7.3 (A) Classical Veress needle. (B) Veress needle disassembled for cleaning
with spring for closing the sharp tip after entering the abdominal cavity visible. All
from MITI.
Figure 7.4 A selection of commercially available disposable Veress needles. From MITI.
Operative (Surgical) Laparoscopy
275
7.1.2.1 Insertion of the Veress Needle
After a small incision of the skin the abdominal wall is elevated to induce
an intraabdominal vacuum. The Veress needle is now cautiously inserted.
As soon as the sharp tip of the needle perforates the parietal peritoneum
and enters the separation line between parietal and visceral peritoneum, the
inner spring-loaded stylet moves forward. Now the lateral hole is given
free which enables CO
gas to be delivered intraabdominally (Fig. 7.5).
2
7.1.3 Gas Insufflators
7.1.3.1 Insufflation Device
The insufflator is a pump to deliver the CO
required to create the artificial space to perform surgery. It is designed to
produce adequate pressure (ca. 15 mmHg) and to maintain it during the
into the abdomen which is
2
Figure 7.5 Pneumoperitoneum: (A) Elevation of the abdominal wall; (B) after the
incision of the skin, the abdominal wall is punctured with the needle. The resistance
of the tissue pushes the mandrin back. As soon as the peritoneal space is reached
the blunt tip moves forward. From M. Scholle.
276
Biomedical Engineering in Gastrointestinal Surgery
procedure even in case of gas leaks, but, simultaneously, pressure
peaks which would be harmful for the patients have to be avoided.
Accordingly, pressure and flow sensors are essential components of an
insufflator (
Fig. 7.6).
Insufflators are equipped with displays indicating the preselected and
the effective intraabdominal pressure as well as gas flow and the total
amount of insufflated gas (
Figs. 7.7 and 7.8).
If there is no central gas supply provided in the OR, gas cylinders
have to be used. In this case, it is important to know when a change of
the bottle is imminent. A gas supply display is therefore an integral part
of the device.
Figure 7.6 Block diagram of an insufflator. The pressure regulation unit reduces the
pressure from the source to a certain limit, the flow control unit regulates the flow
depending on user preferences and measured intraabdominal pressure. From MITI.
Figure 7.7 Gas insufflator, front panel: a, power switch; b, gas supply; c, intraabdominal pressure; d, insufflation flow; e, insufflated volume; f, tube to patient connector.
From MITI.
Operative (Surgical) Laparoscopy
Figure 7.8 Gas insufflator, rear panel: a, gas inlet; b, ground connector; c, mains
plug; d, SCB (STORZ Communication Bus) connector, bus system to transfer data to
other peripheral devices; e, holder for small gas bottle if the insufflator is mounted
on a trolley. From MITI.
277
To avoid critical pressure peaks an acoustic/visual alarm is activated
as soon as the intraabdominal pressure exceeds the preselected setting,
e.g., due to contraction of the abdominal muscles if relaxation decreases.
Medical grade CO
is insufflated passing through a filter, commonly
2
at room temperature, with a relative humidity approaching 0%.
Currently, there is a trend to integrate additional devices to warm and to
humidify the insufflated gas to avoid the potential detrimental effects
of desiccation and the loss of temperature. The real clinical significance is
still a matter of debate.
7.1.3.2 Creation of the Pneumoperitoneum
Prior to the insertion of the Veress needle a small incision of the skin has
to be made to reduce resistance of the skin (
Fig. 7.9).
The next step is to lift up the abdominal wall, e.g., by using Backhaus
clamps as seen in
Fig. 7.9B to create an intraperitoneal negative pressure.
The Veress needle is, then, inserted. It is important to keep the needle
firmly at the outer trocar (
Fig. 7.10).
In the beginning, a low flow (1 L/min) has to be selected to reduce
the risk if the Veress needle is in a wrong position. If it is correctly placed
within the peritoneal space, the intraabdominal pressure will be zero or
even negative in the beginning.
If the gas can flow in freely, the actual flow should be as high as the
preselected flow.
With a continuing insufflation, the intraabdominalpressurewillgradually
increase until the preselected intraabdominal pressure (usually 15 mmHg) is
278
Biomedical Engineering in Gastrointestinal Surgery
Figure 7.9 (A) A scalpel is used to cut through the skin, to facilitate the insertion of
the Veress needle; (B) the abdominal wall is lifted up and the Veress needle is
advanced. All from MITI.
Figure 7.10 (A) Insufflated abdomen before removing the Veress needle; (B) measuring the key parameters during initial insufflation to make sure that the Veress needle
is positioned correctly. All from MITI.
reached. Higher intraabdominal pressure causes postoperativ e pain. Lower
pressure is potentially more comfortable for the patient in the postoperative
phase, but reduces the available space intraoperatively
[1].
As soon as the first trocar has been inserted safely into the abdomen,
gas flow is switched to the maximum (30 L/min in most devices).
Recently, a revolutionary new approach was presented on the market.
The so-called Air Seal system (SurgiQuest, Milford, CT, the United States)
does not require tight fittings of the instrument but allows free use of
instruments of large and small diameter. This valve- and membrane-free
system is based on a high duty gas pump which provides a gas stream which
creates a sealant layer of gas serving as a fitting. Responding immediately to
the slightest changes of intraabdominal pressure, a stable pneumoperitoneum is continuously maintained, even under suction. Continuous smoke
279Operative (Surgical) Laparoscopy
evacuation always provides good visuability [2]. The system, however,
is significantly more expensive than standard insufflation technology. The
noise produced may be irritating. Clinical evaluation is currently being
performed
[3].
7.1.4 Trocars
Trocars are devices made up of an obturator, the cannula (a hollow tube),
and a seal. Frequently, an insufflation tap is also integrated.
With trocars, pathways into the abdominal cavity are created to
insert the camera and the instruments into the abdomen. Cannula sleeve
diameters are usually 1 mm larger than the instruments to be introduced
through them. Of note, 1012-, 10-, and 5-mm trocars with pyramidal
or conical obturators are usually employed for laparoscopic surgery. The
stylets on reusable trocars should be sharpened regularly. Disposable
trocars offer sharp stylets and tip shields that may help avoid organ injury.
These, however, are not foolproof and do not supplant proper insertion
techniques. The newest single-use trocars incorporate antisplashback
features and universal valves that allow instruments ranging from 5 to
11 mm to be introduced without attaching converters. If the patient has
had previous surgery, and difficulties are encountered in achieving the
pneumoperitoneum, an open laparoscopy may be attempted, using
a Hasson cannula. A direct cutdown is made into the abdominal cavity,
followed by stay sutures placed in the fascia. The cannula is placed in the
abdomen and secured in place with the stay sutures. CO
attached, and insufflation commences through the Hasson cannula.
Both reusable and disposable trocars have in common the following
items (
Fig. 7.11).
Trocars are a very lucrative market. Accordingly, the spectrum of
commercially available products is very broad.
tubing is then
2
7.1.4.1 Reusable Trocars
This market is dominated by STORZ, WOLF, AESCULAP, and others,
mostly German companies. This type of trocars is usually made of metal
(
Fig. 7.12). For cleaning, reusable trocars can be disassembled. A major
problem of this type of trocars is to provide adequate caliber reduction if
instruments are used which have a smaller diameter than the maximum
diameter of the trocar. Specially designed converters and reduction tubes
are provided.
280
Biomedical Engineering in Gastrointestinal Surgery
Figure 7.11 (A) Disposable trocar; (B) reusable trocar. All from MITI.
Figure 7.12 (A) Pyramidal, sharp tip. The valve can be opened actively using the
lever. Standard length and diameter (10 mm); (B) like in (C) and (D), the shaft bears a
helical structure to prevent slipping of the trocar within the port site; (C) Like B with
prolonged blunt obturator; (D) trocar for pediatric surgery: it is shorter with a smaller
diameter. From MITI.
Operative (Surgical) Laparoscopy
Figure 7.13 Disposable access systems. These instruments are designed for single
use. A 12-mm internal diameter with a deployable blade access system is shown in
(A). The next device (B) also has a 12-mm internal diameter, but has a blunt tip that
is used to pass through the abdominal wall. (C) is a trocar for the semiopen access
(Hasson technique). On the left, the inflatable balloon is seen to seal the abdomen.
On the right, an additional nozzle is visible below the insufflation cock to inflate/
deflate the distal balloon. (D) is a simple trocar for 5-mm instruments. No connection
to the insufflation system is provided. (B) and (D) bear a helical structure on the shaft
to prevent slipping. From MITI.
281
7.1.4.2 Disposable Trocars
This type of trocars is usually produced as a plastic device. After a single
use, they are discarded (
Fig. 7.13).
7.1.4.3 Hybrid Systems
Some companies try to combine the advantages of reusable trocars with
the advantageous features of disposable trocars by offering partly reusable
and disposable systems.
7.1.5 Visualization
7.1.5.1 Laparoscopes (Laparoscopic Telescopes)
The quality of the video image is the key to a safe and fast surgical intervention. Up to now, Hopkins rod lens systems are the gold standard. Rod
lens systems were developed by the physicist Harold Hopkins in the 1960s.