Page 26 - Clinical Manual of Small Animal Endosurgery

14 Clinical Manual of Small Animal Endosurgery

Irrigation can be provided by devices that apply pressure on a fluid
bag, but electronically controlled irrigators guarantee precise flux and
irrigation pressure. Suction tips can be reusable or disposable: the latter
are preferable, especially in laparoscopy, as they allow fine regulation
of the intensity and duration of suction. This avoids loss of pneumoperi-
toneum, which otherwise can occur with excessive removal of gas by
suction.

Insufflator
In flexible endoscopy an air pump is adequate for displacing the
mucosa from the distal end of the endoscope, thus allowing visualisa-
tion. In thoracoscopy, a working space is created by creation of
a controlled partial pneumothorax and/or selective lung ventilation,
and thoracic insufflation is needed only rarely. In laparoscopy, intro-
duction of gas is instead required to induce pneumoperitoneum.
Air, nitrous oxide and carbon dioxide have all been used for this
purpose; carbon dioxide is the gas of choice because it is more readily
absorbed in blood, thus minimising the risk of gas embolism, and
spark ignition is prevented when diathermy is used. The carbon
dioxide is delivered from a cylinder of compressed gas (or via piped
gas supply) by an insufflator (Fig. 1.14).
Carbon dioxide can be delivered initially either with a Veress needle
or using a semi-open technique (Hasson or paediatric technique), in
which the gas is insufflated directly through a cannula. After cannula

Fig. 1.14 An electronic insufflator. The operator sets the pressure level at
which insufflation is maintained as well as the maximum instantaneous
flow rate.