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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_605_Библиотеки_им_академика_М_И_Перельмана.pdf
Classical (Open) Surgery
Figure 6.16 (A) A selection of dedicated vascular clamps: (a) Bulldogs forceps: This
is a class of forceps differing considerably from normally hinged forceps. It is spring
loaded. By squeezing the proximal shanks, the tip opens and the forceps is positioned on the artery. By releasing the pressure, the vessel is occluded. (b) Satinsky
clamp; (c) Cooley clamp. Particularly suitable for tangential temporary exclusion
of larger vessels; (d) Dardik; (e) De Bakey: The long tips enable to modify the pressure
exerted to the tissue: The closer to the articulation the tissue is positioned, the
stronger is the force. (B) Straight and curved Bulldog clamps (magnified). All from MITI.
231
exerts significantly less trauma. After successful surgical repair, blood flow
is reestablished by releasing the clamps. Any pressure damage to the vascular
wall—in particular of the intima (innermost layer)—favors the formation of
thrombosis and endangers the success of the surgery.
The difficult combination of (elastic) strength and gentle manipulation
of the tissue stimulated the design of very sophisticated vascular clamps
(
Fig. 6.16).
Bulldog clamps are a particular subtype of hemostats with a very short
handle. They can be positioned in the surgical site when it is very
crowded. The jaws are opened by squeezing the handle. When the
pressure is released from the handles, the clamp closes and stops blood
flow until it is removed again.
Vascular clamps are not exclusively used by vascular or cardiac surgeons
but by visceral surgeons as well.
6.1.5 Retractors
Surgical retractors are medical instruments used to separate the edges
of a wound or incision. This instrument offers surgeons access to an area,
while inflicting a min imal amount of damage to the wound. Surgical
technologists or assistants may be responsible for holding these
232
Biomedical Engineering in Gastrointestinal Surgery
Figure 6.17 (A) Handheld retractors: (a) Gillies hook with sharp, thorn-shaped tips
for skin retraction; (b) Volkmann hook: Sharp teeth to retract skin/subcutaneous
tissue; (c) Langenbeck hook: Smooth blades; (d) Roux hooks; (e) Abdominal wall
retractor (Fritsche); (f) Retractor for internal organs (Doyen), such as liver and small
bowel. (B) Instrument tray with a variety of retractors. All from MITI.
Figure 6.18 (A) A pair of Roux hooks to separate the edges of an inguinal incision;
(B) Liver hook (1) maintains the adequate position of the liver to give access to the
hepatoduodenal ligament. All from MITI.
instruments in place during an operation. In addition to handheld retractors (
Fig. 6.17A), so-called self-retaining retractors are available. They are
usually provided together in the so-called retractor tray (
Fig. 6.17B).
For an optimal exposure of the surgical site, it is of utmost importance
to hold back the adjacent tissues and organs, which is often a tedious and
boring task for the assistant whose task it is (
Fig. 6.18).
6.1.6 Self-Retaining Retractors
Retractors have to distract incisions and accesses by exerting traction
forces on both sides of the access. Accordingly, two hooks are required.
Classical (Open) Surgery
233
Figure 6.19 Two types of self-retaining retractors: (A) Self-retaining retractor for skin
incision (Weilander). The jaws are kept within their selected position by the arresting
mechanism with the liver. (B) Four (or more) hooks are mounted on a ring to keep
an abdominal incision open (Zenker). From MITI.
If these are connected by a hinge, the distension force can be maintained
mechanically (
Fig. 6.19).
Self-retaining retractors often enable the surgeon to do the operation
(usually smaller ones) without the help of an assistant (“solo surgery”)
(
Fig. 6.20).
For larger incisions, in particular of the abdominal wall, more complex
devices are in use. In
Fig. 6.21 a ring-shaped retractor (Zenker) and an addi-
tional pulled hook are shown. The pulled hook is connected to an anchor.
The traction can be varied to permit a wide access to the abdominal cavity.
6.1.7 Needle Holders
The purpose of this hemostat-like instr ument is to hold the surgical
needle firmly during surgery. Whereas a tailor is able to manipulate the
234
Biomedical Engineering in Gastrointestinal Surgery
Figure 6.20 Self-retaining retractor in situ. The two edges of skin/subcutaneous tissues are kept apart, facilitating further tissue dissection in deeper layers. From MITI.
Figure 6.21 Abdominal incision. Hooks mounted to the metal ring permit a good
access to the abdominal organs. Note the additional pulled hook. From MITI.
needle with bare fingers, suturing in surgery is only feasible by the use of
needle holders. Usually, needle holders have an integrated clamp mechanism which locks the needle in place as long as it is required. Two main
types exist: The Mayo-Hegar (
(
Fig. 6.22B). In a Mayo-Hegar needle driver the clamp mechanism is
Fig. 6.22A) and the Mathieu variant
released by lateral pressure to the bows. The Mathieu-type needle holder
is opened by squeezing the handles beyond the point of arrestment.
Classical (Open) Surgery
Figure 6.22 The most often used needle drivers in abdominal surgery: (A) MayoHegar; (B) Mathieu. From MITI.
235
The design of the tip is a particular challenge. On the one hand,
a firm grip on the needle has to be maintained. On the other hand, any
mechanical deformation of the needle has to be avoided strictly. The
texture or structure of the jaws must offer the best trade-off. As soon
as they are becoming blunt, they have to be exchanged (
Fig. 6.23).
In surgical ORs all over the world, it is striven to provide the
instruments in a very standardized manner and adapted to the particular
application. Standardized containers for basic surgical operations (
Fig. 6.24)
are complemented by additional specialized containers.
6.1.8 Others
In addition to the “general purpose” instruments as mentioned above,
a wide range of highly specialized instruments is additionally provided.
They are designed to enable the surgeon to perform only one or just
a few well defined—but cr ucial—steps of the operation.
Stone forceps are a typical example. These funny shaped instruments
are required to remove stones out of the common bile duct or the pelvis
of the kidney/ureter (
Fig. 6.25).
Figure 6.23 Needle driver in action. It is locked, keeping the needle in a
stable position which overcomes tissue resistance. The needle is fixed in a rectangular position. From MITI.
Figure 6.24 Two instrument trays for basic surgical interventions. (A) Clockwise:
Hemostats, retractors, scissors, forceps. (B) Clockwise: Pads, kidney dishes, clip
applier. All from MITI.
Classical (Open) Surgery
Figure 6.25 Stone forceps. The different angles allow for a good anterograde and
retrograde positioning of the forceps within the duct system. From MITI.
237
Another instructive example of a highly specialized instrument is the
so-called purse string clamp. If it is considered necessary to perform a socalled “staple anastomosis” using a circular stapler, the stump of the GI
tract which will later on bear the anvil of the stapler (usually distal esophagus or proximal colonic stump) has to be prepared by means of a purse
string (see
Section 6.5: Stapling Devices). A purse string is a continuous
suture which is stitched around the circular edge of the stump.
When it is closed by knotting, the shaft of the anvil will fit snugly
into the stump. This time-consuming process of stitching the suture
around the edge can be considerably simplified by applying the suture
clamp (
Fig. 6.26).
For the nonsurgical reader, the detailed mode of action is perhaps difficult to understand, but the message should be clear: Even in conventional surgery, particular problems which were valid in surgery for many
decades can be overcome by the invention of an apparently simple and
logical new approach (“the egg of Columbus”). The authors are convinced that there is—still after about 150 years of conventional surgery—
a high potential for improvements, like the one shown above.
6.2 ELECTROSURGERY
When using the principles of electrosurgery to cut tissue, heat is applied
only to small locally distinct tissue areas. Electrosurgery does not have
an impact on the systemic temperature of the patient, but it does have
Figure 6.26 The purse string clamp: (A) The highly sophisticated jaws have specially
designed teeth with needle canals. After correct positioning of the clamp, the surgeon
just has to place the two needles of a double armed suture through the two needle
channels and to remove the clamp. (B) Sigmoid resection: The upper part has to be
removed. The lower part remains in the body. Later, it has to receive the anvil of the
circular stapler (see
der. (C) The two needles of a thread are inserted into the needle channels. (D) The upper
part of the sigmoid is cut off with a scalpel. (E) The clamp is removed. Note the two
ends of the purse string suture (above). The anvil can now be introduced. All from MITI.
Section 6.5: Stapling Devices). The clamp is positioned on the bor-
239Classical (Open) Surgery
a severe impact on local tissue and therefore cells adjacent to the heat
input. Thermal effects occur if cells are exposed to temperatures out of
the thermo-neutral zone between 35˚C and 41.5˚C. All thermal effects
are dependent on the intensity and duration of the thermal input. It is,
therefore, not important how the specific temperature is reached and how
it is induced. This chapter will further breakdown low- and hightemperature effects into five groups of thermal effects that biological tissue
can pass through when it is heated above 37˚C.
6.2.1 Thermal Low-Temperature Effects
Human beings are homeothermic. That means that the core temperature
is regulated by internal metabolic processes within a narrow bandwidth
of 0.5 K. The human body core temperature is 37˚C independently
of the ambient conditions. This core temperature is needed to maintain
all physiological processes running and is regulated by the hypothalamus
by dilation and contraction of blood vessels. Human cells are very sensitive to temperature changes. The first effects occur at around 35˚C if the
temperature is lowered and 41.5˚C if the temperature is increased. Both
effects are used for medical purposes.
Targeted lowering of local temperature is used, e.g., for cryotherapy
to destroy lesions. Heating of tissue has an influence which is used for different purposes. Since electrosurgery is mainly based on heat, only tissue
effects due to increasing temperature are described in detail.
gives an overview of the low-temperature effects of hyperthermia, devitalization, coagulation, and desiccation, furthermore showing the different
thermal effect zones exemplified for a monopolar active electrode
The thermal effect which is induced by the highest thermal input always
lies in the closest proximity to the active electrode.
Fig. 6.27A
[5].
6.2.2 Hyperthermia and Devitalization
When normal body temperature is raised no irreversible effects will occur
until the tissue temperature reaches 41.5˚C. This temperature zone is
called “hyperthermia.” If the temperature of human tissue is raised above
41.5˚C an irreversible “devitalization” effect will occur. At this temperature level time is of great importance. With increasing temperature the
devitalization will stride forward and will irreversibly damage the tissue.
The devitalization effect is time-dependent up to a temperature of 49˚C.
If temperatures of more than 49˚C are reached the devitalization of the
240
Biomedical Engineering in Gastrointestinal Surgery
Figure 6.27 Thermal low- and high-temperature effects—high-frequency current
application to tissue through a monopolar electrode causes diverse thermal defects.
(A) Low-temperature effects are caused through ohmic current flow from the electrode to the tissue and can be divided into three zones: temperatures above 41.5°C
lead to devitalization; temperatures above 60°C lead to coagulation; and temperatures up to 100°C lead to desiccation. (B) High-temperature effects are caused by
electrical arcs sparking from the electrode to the tissue and can be divided into two
zones: temperatures above 200°C leading to carbonization and temperatures above
500°C leading to vaporization of tissue. To achieve high-temperature effects temperature ranges that cause low-temperature effects have to be passed through. Thermal
effects occurring at the highest temperatures are always in closest proximity of the
electrode. From MITI.
target tissue will occur almost instantaneously. One of the two treacherous
characteristics of devitalization is the low-temperature difference to the
standard tissue temperature by only 4.5˚C. Furthermore, the fact that
devitalized tissue does not change in tissue color or structure and therefore cannot be seen with reasonable effort is cr ucial. If heat input has
raised the tissue temperatures above 41.5˚C and below 60˚C, the tissue
will be damaged irreversible, nevertheless not noticeable for the human eye
[6]. Surgeons and endoscopists do not have the ability to make the devitali-
zation zone visible. If the devitalization reaches into the muscularis propria
and the damaged muscle tissue disintegrates several hours after the intervention, delayed perforations and bleedings may occur. These are dangerous
to life and must be surgically treated instantly. During cutting and coagulation processes, the devitalization is an unintended side effect, but it can also
be used meaningful, e.g., for tumor destruction.
6.2.3 Thermal Coagulation
The second low-temperature effect is called “thermal coagulation” and sets
in at a temperature level above 60˚C. Coagulation is defined as the