Page 122 - Clinical Manual of Small Animal Endosurgery

110 Clinical Manual of Small Animal Endosurgery

Surgical technique

The first step in laparoscopy is induction of pneumoperitoneum. This
can be achieved with the use of either a Veress needle (closed technique)
or a Hasson trocar (open or paediatric technique). Palpation of the
abdominal cavity is recommended before needle insertion, in order to
identify underlying organs – most commonly the spleen – which must be
avoided. The Veress needle is usually inserted at the same site as the first
telescope portal; this is often located caudolateral to the umbilicus, where
the abdominal wall is consistently thin (Kolata and Freeman, 1999a). A
1 mm skin incision is performed at the selected site, and the abdominal
wall is lifted and tented by grasping it with forceps. The Veress needle
is then inserted directed caudally at an angle with the skin, thus avoiding
the spleen and the falciform ligament. Other measures directed at mini-
mising risk of iatrogenic organ damage are placing the animal with the
head slightly down (Trendelenburg position), and resting the heel of the
non-dominant hand on the abdominal wall, to control the needle entry.
The Veress needle is grasped by the hub during abdominal wall inser-
tion, thus allowing retraction of the inner blunt stylet. Once the abdomi-
nal cavity is entered, and no more resistance is encountered, the outer
trocar retracts, and the spring-loaded blunt stylet protrudes, minimising
the risk of trauma to the abdominal organs. After insertion, the needle
is gently swept in a circular pattern against the abdominal wall, thus
freeing it from any adhesions or omentum.
To verify appropriate intra-abdominal placement, the ‘hanging drop
test’ is performed. This entails attaching a syringe partially filled with
saline to the hub of the Veress needle. After having applied gentle suction
to confirm the absence of blood or fluids, a drop of saline is placed into
the hub of the needle, and the abdominal wall is tented. If the needle is
properly placed in the peritoneal cavity the negative pressure present in
the abdominal cavity aspirates the drop into the needle hub. Correct
placement is extremely important, as placement into an organ, vessel or
mass causes haemorrhage, which interferes with visualisation, and can
also result in a fatal embolism.
The needle can also be incorrectly placed into the subcutaneous tissue,
or into the omentum or falciform ligament. Subcutaneous placement
results in subcutaneous emphysema, which will greatly increase the
difficulty of the procedure. Subcutaneous emphysema will resolve in
approximately 48 h. Similarly, insufflating carbon dioxide below the
omentum or within the falciform ligament causes expansion of these
structures, and consequent obscuration of the field of view.
Once correct placement of the needle is confirmed, the Luer-lock
attachment at the hub of the needle is connected to the insufflation
tubing, and pneumoperitoneum is established (Fig. 4.4). The pressure
within the abdominal cavity should be initially low (2–3 mmHg), and
carbon dioxide should be delivered at a rate of at least 1 L/min. Greater
intra-abdominal pressure, or a flow rate close to zero, are suggestive of