Page 119 - Clinical Manual of Small Animal Endosurgery

Diagnostic Laparoscopy 107

in fact not become evident for several hours, as volume expansion with
fluid shifted from the extravascular space takes approximately 4 h, and
splenic recruitment of red blood cells offsets the fall in packed cell
volume even longer (Villiers, 2005). When the blood loss is less than
20%, crystalloids will suffice, whereas if the blood loss is between 20
and 30% colloids are necessary. Blood transfusion should be considered
if the blood loss approaches 30%, as physiological mechanisms are no
longer able to compensate.
Carbon dioxide embolism presents with a severe and sudden drop in
blood pressure, development of a heart murmur, cardiac dysrhythmias
and cyanosis. A rapid and transient rise in end-tidal carbon dioxide as
the gas embolises is followed by a steep decline in this parameter, due to
reduction of blood delivery to the pulmonary circulation (Staffieri et al.,
2007). Capnography, together with ECG and blood-pressure monitor-
ing, will assist in rapidly detecting carbon dioxide embolism.
An accidental perforation of the diaphragm, or a pre-existent congeni-
tal or acquired defect, may cause pneumothorax, which manifests itself
with a change in ventilator pattern, accompanied by cyanosis, drop in
PaO2 and caudal bulging of the diaphragm. Due to the positive perito-
neal pressure, a tension pneumothorax will develop, which may be fatal
if not rapidly recognised and treated. Increase in the minute ventilation,
evacuation of the gas from the thorax with a thoracostomy tube, and
abdominal desufflation are able to reverse the physiological effects while
the laceration in the diaphragm is repaired. Conversion to open surgery
is often necessary.
Postoperative care of animals undergoing laparoscopy includes multi-
modal analgesia, with parenterally administered opioids, and non-
steroidal anti-inflammatory agents whenever possible. Although the
discomfort after laparoscopy is mostly due to formation of carbonic acid
on serosal surfaces, causing peritoneal inflammation and phrenic nerve
irritation rather than incision-related pain (Magne and Tams, 1999),
injection of local anaesthetic agents at the port sites at the beginning or
at the end of the procedure is considered beneficial. Long-acting local
anaesthetic agents such as bupivacaine or ropivacaine are always used;
as their onset of action is delayed, a cocktail with lidocaine is preferred
when the block is carried out at the end.
In preparation for laparoscopy the bladder should be emptied to mini-
mise the risk of accidental puncture with the Veress needle or a trocar.
The stomach and occasionally colon may need to be evacuated if they
are distended. Distended viscera will also decrease visualisation of the
surrounding areas.
The animal should always be clipped liberally, from 5 cm cranial to
the xiphoid process to the pubis. Laterally, the patient is clipped as for
a traditional open coeliotomy, and the whole clipped area is prepared
aseptically. This will enable conversion to an open procedure should
the necessity arise. This may happen because of technical difficulties or
complications, or in case a surgically correctable lesion is encountered.