Biomedical Engineering Reference
In-Depth Information
trauma to the rectal mucosal surface when using this
technique.
Fecal samples needed for bacterial culture are collected
using a cotton-tipped swab or a disposable fecal collection
kit. The swab is inserted through the anus and gently
rotated around the internal mucosal surface of the rectum.
Swabbing increases the recovery of mucosal surface-
dwelling bacteria, and is therefore superior to merely
inserting then removing the swab from the anal canal. As
certain bacterial organisms are relatively sensitive to the
effects of drying, the specimen must be quickly placed in
the proper transfer media.
(13.3-mm diameter, 168-cm working length) may be
inserted approximately 100 cm to reach the cecal colic
junction. For tamarins and marmoset a procedure has been
described using a pediatric bronchoscope with a 4.8-mm
insertion tube (
Clapp et al., 1987
). The colon is expanded
with air to permit improved visualization of the colonic
mucosa, which takes place during insertion rather than
extraction of the device. It is essential to remain mindful of
the fact that the endoscope itself may cause trauma to the
intestine, potentially resulting in misdiagnosis.
Liver
Liver biopsies are sometimes needed as a clinical diag-
nostic tool and may be performed using the open, closed
(
Miller et al., 1978
), or laparoscopy (
Fanton, 2005
)
approach. The major advantage of the closed technique is
that it is rapid, does not require major survival surgery, and
allows for a quicker recovery. The open procedure offers
the advantages of visualization of the liver, selection of the
biopsy site, and better control of any associated hemor-
rhage from the biopsy. Endoscopy offers visualization of
the liver while still having a very small incision.
Needle biopsy techniques are performed blindly or with
ultrasound guidance or endoscopic visualization. One
report (
Miller et al., 1978
) described a method performed in
rhesus monkeys. After surgical depth of anesthesia has
been reached, a 1.9
Endoscopy/Colonoscopy
Upper endoscopy is indicated for problems associated with
the esophagus, stomach, and proximal duodenum. Because
upper
endoscopy requires
an empty stomach,
the
nonhuman primate should be fasted for 12
16 hours. For
this procedure, heavy sedation or light anesthesia is needed.
A bite guard should be placed in the animal's mouth to
prevent damage to the endoscope. Speculums are
commercially available but can also be readily fashioned
from a syringe case, block of wood, or hard plastic tube. In
young adult rhesus monkeys, a 9.5-mm diameter insertion
tube may be used (
Authier et al., 2006
). A sterile lubricant
is used to facilitate introduction into the esophagus. To
visualize the pylorus, the stomach is slightly inflated and
the endoscope advanced along the greater curvature and
into the antrum.
For diagnosing diseases of the large intestine, endo-
scopic evaluation of the colon using a flexible endoscope
can be of value. A bowel preparation procedure has been
well described (
Blackwood et al., 2008
). In order to
completely empty the gastrointestinal tract, animals should
be fasted for 36 hours prior to colonoscopy. Anything
ingested during this time may increase the difficulty and
reduce the diagnostic capacity of the examination.
Approximately 24 hours prior to the procedure, a bowel
cleansing agent (GoLytely, Braintree Laboratories, Brain-
tree, MA) is administered. The initial 30 ml/kg of the
solution is given slowly to an anesthetized animal through
an orogastric tube. The remaining solution is decanted into
a cage water bottle for the animal's voluntary consumption
during the day. If, toward the close of the day (approxi-
mately 6 hours later) fluid remains in the water bottle, the
animal is again sedated and dosed to fulfill the required
ingestion of 60 ml/kg.
Colonoscopy begins by placing the animal in sternal or
left lateral recumbency. The scope is lubricated, inserted
into the rectum and, depending on the animal's size, slowly
advanced into the colon approximately 8
e
70 mm biopsy needle is inserted into
the right side of the abdomen at a point where maximum
dullness is heard by percussion between the seventh and
ninth ribs at the mid-axillary line. Once through the inter-
costal muscles into the abdominal cavity, the nonhuman
primate is rotated to a dorsal recumbent position. The
biopsy needle is then flushed with saline to flush out any
muscle tissue encountered when penetrating the intercostal
muscles before being inserted into the liver. Suction may be
used to assist in recovering liver tissue in the biopsy needle.
Ultrasound visualization allows accurate percutaneous
placement of a Tru-Cut biopsy needle while avoiding major
blood vessels. The liver is approached through a right
subcostal skin incision made after aseptic preparation.
Alternatively, insertion of an endoscope may be used to
visualize percutaneous placement of a Tru-Cut biopsy
punch. The nonhuman primate is positioned in a slight
reverse Trendelenburg and the biopsy instrument is inserted
through an aseptically prepared subcostal skin incision and
into the liver (
Fanton, 2005
).
URINARY SYSTEM
Free Catch
Urine samples may be collected by training nonhuman
primates to urinate into pans at the onset of the light period
25 cm proximal
to the rectum (
Blackwood et al., 2008
). For larger primates
such as baboons and chimpanzees, a human colonoscope
e
