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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1841_Библиотеки_им_академика_М_И_Перельмана.pdf
RESECTION PRINCIPLES
113
Mobilization of the liver
In order to perform a liver resection, mobilization of the liver will usually be
required. Whilst small wedge resections or left lobe tumours may require
much less mobilization than right-sided tumours, the general principles apply
but can be tailored for the particular tumour or tumours requiring excision,
but avoid unnecessary mobilization because of the possibility of a subsequent
further hepatic resection.
Incision
A rooftop incision is performed 2–3cm below the costal margin ( Fig. 3.8 ).
If doubt exists about operability, a right subcostal is first made and an assess-
ment performed of the liver and abdominal cavity. The rooftop incision with
a vertical ‘Mercedes Benz extension’ if required, combined with forceful retrac-
tion under the ribs towards the patient’s head ( Fig. 3.9 ) generally provides
adequate access for primary liver resections.
As many patients have had previous abdominal surgery, intra-abdominal
adhesions are not uncommon and slow, meticulous dissection may be required
Fig. 3.8 Rooftop incision
with possible vertical
midline extension.
LIVER
114
to gain exposure to the liver. For right-sided resections, the gallbladder is
removed incidentally using the principles described in Section 5. For segments
II and III it is usually not removed. Initially a tape is placed around the portal
vein, CBD, and hepatic artery and a clamping system is used (see Fig. 3.6 )
which enable a Pringle manoeuvre to be performed if required. Many regi-
mens for such clamping and releasing exist and we currently routinely perform
10–15-min occlusion, 5 min release. It should be noted that not all resections
require a ‘Pringle’ manoeuvre and if a safe bloodless resection is possible with-
out clamping liver inflow, this is clearly desirable. Attention now moves to the
falciform ligament. This needs to be freed from the liver by diathermy close to
the liver capsule until it begins to diverge around the vena cava. At this point,
sharp dissection is used to identify the cava and anterior surfaces of the right
and left hepatic veins. If a left segment II and III lobectomy is to be performed,
the left lobe is mobilized from the diaphragm and the left phrenic vein identi-
fied on the inferior surface of the diaphragm and used to identify the left
hepatic vein into which it drains.
For right hepatectomies, a more demanding mobilization is required. The
peritoneal reflection inferiorly on the right lobe can be divided. The cava is
then slung above and below the liver ( Fig. 3.10 ). The right lobe is then retracted
Fig. 3.9 Forceful fixed upward retraction together with a slight degree of ‘head up’.
RESECTION PRINCIPLES
115
by an experienced assistant standing on the left side of the patient and the
small veins connecting the liver to the vena cava are ligated and divided. Clips
can be used for the smaller caval vessels but those greater than 2–3mm need
suture ligation with a 4/0 Prolene stitch. This process continues cephalad and
anterior to the cava until the liver is seen to be free of any caval connections.
Care must be taken at this point to identify the right adrenal gland and its vein
and ensure that it is displaced posteriorly. This is usually straightforward with
problems only occurring if there is tumour adjacent to, or involving the gland.
As the dissection proceeds towards the right hepatic vein a small band of
fibrous tissue on the right side of the right hepatic vein (the hepatocaval liga-
ment) needs to be carefully divided. Once this is achieved, it is almost always
possible to isolate the right hepatic vein outside the liver and it can have a vas-
cular loop passed around it ready for later vascular stapling or ligation. At this
stage, with control of the inflow possible and slings around the inferior vena
cava (IVC) above and below the liver, the liver is now ready for transection.
In these circumstances, it is important to have the central venous pressure as
low as possible. This helps minimize blood loss from back bleeding through
the hepatic veins which have no valves. Inflow control can be simply achieved
by a number of methods (clamping the pedicle or a formal Pringle manoeu-
vre) but hepatic venous back pressure and flow is more difficult to achieve
mechanically and maintaining a reduced central venous pressure is extremely
helpful. Close cooperation with the anaesthetist is essential in order to achieve
Fig. 3.10 The inferior vena cava can be mobilized superiorly above the hepatic veins
and inferiorly above the renal veins to provide venous control if required.
LIVER
116
a central venous pressure between zero and 4mmHg, minimizing the risk of air
embolus and venous bleeding. When this is achieved blood loss is significantly
reduced.
Intraoperative ultrasound has become a basic tool for the hepatobiliary sur-
geon (Bloed et al ., 2000 ; Zacherl et al ., 2002 ). It can be used over the liver, once
it has been freed of attachments and any adhesions, to assess the extent of
tumours present. Complete ultrasound assessment must wait until the right
hepatic lobe has been fully mobilized. This combined with bimanual palpation
will reveal most disease. It is vital not to forget to assess the caudate lobe by
both palpation and intraoperative ultrasound. While intraoperative ultra-
sound is an essential tool for hepatobiliary and pancreatic surgery, it is worth
acknowledging that identifying additional tumours not detected by bimanual
palpation alone is only likely in 10% of patients (Kane et al ., 1994 ; Jarnagin
et al ., 2001 ).
The hepatic pedicle
Hilar dissection
The anatomy at the hilum is complex and the variability of the arterial and
biliary components in the hepatoduodenal ligament ( Fig. 3.11 ) and at the
Fig. 3.11 Vascular and biliary anatomy at the hilum.
RESECTION PRINCIPLES
117
hilum means that the dissection in this area must be based on sound principles
rather than the expectation that a detailed knowledge of all possible variations
will allow a specific pattern to be identified, and the procedure blindly based
on this ( Fig. 3.12 ).
A safe and standard approach adds flexibility if the planned resection has to
be changed due to unexpected intraoperative findings. The approach to the
hilum must also allow different conditions and pathologies, including tradi-
tional anatomy in liver resections (metastases and primary liver tumours),
hilar cholangiocarcinoma, bile duct injuries, and penetrating trauma to be
approached with confidence.
The initial step in the hilar dissection is to exclude tumour involvement by
manual palpation after division of the lesser omentum. This is assisted by the
use of intraoperative ultrasound, which gives excellent views of the hilum and
tumours and allows their relationships to be precisely determined. Having
shown that the tumour does not directly involve the hilar structures, a stand-
ard cholecystectomy is performed as described in Section 4 ( Fig. 3.13 ).
The cystic artery and duct are ligated and transfixed. Biliary structures are
transfixed distal to the ligature and arterial proximal; the rationale is based on
securing the watertight closure of the bile duct but preventing problems with
upper abdominal vessels where ligatures cut in and may completely divide the
vessel and bleed unless transfixation is proximal. The hepatoduodenal liga-
ment is then carefully re-examined to determine the arterial anatomy by pal-
pation. This frequently identifies abnormal and additional vessels together
with any early division. An accessory left hepatic artery should also be sought
Fig. 3.12 Common variations in the biliary anatomy at the hilum and the approximate
frequency with which they occur: 1:57%, 2:16%, 3:12%, 4:5%, 5:4%, 6:2%, 7:2%,
8:1%, 9:1%.
LIVER
118
in the lesser omentum. The presence of this vessel not only aids resection
planning, but if it is large it is often associated with a small, difficult to feel
(especially after dissection) left hepatic artery.
An early division of the hepatic artery occasionally allows it to be slung at
this stage but we prefer dissecting more fully before slinging structures. Initially,
the bile duct is generally identified by following the cystic duct to its junction
and dissected free and slung ( Fig. 3.14 ).
The tissue in the right free border of the hepatoduodenal ligament is then
dissected and removed by ligation and division to avoid lymphatic leaks. The
portal vein is identified and slung ( Fig. 3.15 ). Developing the plane anterior to
the vein allows the bile duct and artery to be mobilized forwards and the bifur-
cation of the vein to be identified—the branch to the residual side to be retained
must be clearly identified.
At this point, the tissue in front (the hilar plate) should be freed from the
base of the liver and this allows all the structures which bifurcate at that point
to be ‘lowered’. The artery and duct are then separated at the bifurcation and
slung just below it.
Attention is then turned to the division of the bile duct and depending on
the resection planned, the ducts and arteries to that side are identified and
slung. With the bile duct it is crucial to remember that the cylindrical structure
represented in line diagrams is frequently not present. Most common techni-
cal problems relate to early division of the right side and this is often likened to
the left hand ( Fig. 3.16 ).
Fig. 3.13 Cholecystectomy
is performed as the first
stage of the hilar dissection.
RESECTION PRINCIPLES
119
Fig. 3.15 The portal vein is
identified and slung.
Fig. 3.14 The hepatic duct
is identified, isolated, and
slung.
LIVER
120
Dissection of the right side must take this into account and unless it is
sufficiently deep then resistance will be mistaken for the posterior aspect of the
‘hilar plate’, the bile duct will be punctured just beyond the bifurcation result-
ing in a bile leak which will need to be repaired.
Lifting the hepatic artery and bile duct forward will then allow the portal
vein to be further exposed and the bifurcation clearly seen. The side to be
ligated is then slung and soft clamps temporarily applied to the artery and
veins ( Fig. 3.17 ).
This will produce a line of demarcation confirming that the structures can
then be safely divided ( Fig. 3.18 ).
The division of these structures should always occur as far away from the
hilum as possible to avoid narrowing after ligation and subsequent transfixa-
tion ( Figs. 3.19 and 3.20 ).
If the distance from the division to the liver is very short, then occasionally,
it is necessary to dissect a short segment intra-parenchymally to ensure a safe
transection. All the three structures are ligated, divided, and transfixed (vascu-
lar proximal, biliary distal).
After division of the major structures, the portion of the liver to be resected
will again demarcate. Any accessory vessels or bile ducts must also be identi-
fied, and the areas they supply or drain defined. If necessary these vessels
too will be divided. This produces a much clearer field when the parenchy-
mal phase of the resection reaches the hilum, and prevents problems with
structures being tethered by these small radicles.
Fig. 3.16 The hilar structure
can be viewed as a left
hand with the thumb at
right angles to the fingers.
The thumb represents the
left main bile duct and
the fingers the division
and orientation of the
right-sided ducts.
RESECTION PRINCIPLES
121
Fig. 3.18 The right hepatic artery and the right branch of the portal vein have been
divided producing a line of demarcation.
Fig. 3.17 The right hepatic
artery and portal vein are
clamped producing a line
of demarcation along the
central fissure.
LIVER
122
Fig. 3.20 The left hepatic
artery, portal vein, and
hepatic duct divided in
preparation for a formal
left hepatectomy.
Fig. 3.19 Right hepatic artery, right branch of the portal vein, and right-sided
hepatic duct divided in preparation for a formal right hepatectomy.