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NOTES Applications in Veterinary Medicine
Lynetta J. Freeman & Karine Pader
Purdue University, West Lafayette, IN, USA
Introduction
A primary goal in surgical research involving animals is
translation – to develop and validate the safety and effi cacy
of new procedures fi rst in animals before performing them
in humans. Swine and dogs are frequently used as animal
models due to the similarities in anatomy and physiology.
Both species were used in developing early cardiac bypass
and open heart procedures. During the 1990s, swine were
used extensively to develop instrumentation and train physicians in laparoscopic and thoracoscopic surgery. Apparently in the history of laparoscopy, the fi rst translumenal
surgery was performed in dogs by George Kelling in 1901
using a transvesical approach to the abdominal cavity to
study the effect of pneumoperitoneum on hemostasis.
Kalloo et al. reported the fi rst NOTES technique (peritoneoscopy) using swine as the model for abdominal exploration
and biopsy procedures [1]. Researchers around the world
have performed experimental NOTES tubal ligation, cholecystectomy, splenectomy, intestinal anastomosis, gastrojejunostomy, nephrectomy, lymphadenectomy, thoracic access,
and colon resection in swine [2] and, recently, hybrid transvaginal ovariohysterectomy [3], bilateral NOTES oophorectomy [4], and NOTES inguinal mesh placement in dogs [5].
In doing so, instrumentation was developed, the safety of
translumenal access and infection control methods were
established, and the physiology of NOTES procedures and
closure of the access means were investigated [2]. These
experimental animal studies provided a strong foundation
for clinical trials of NOTES procedures.
Clinical utilization of new technology in veterinary medicine for MIS in animals has lagged behind human medicine,
primarily limited by fi nancial constraints of practice owners
in purchasing equipment, the need for specialized training,
and the additional costs for the procedure. Veterinarians
must address a wide variety of medical and surgical procedures in many species ranging in size from a few hundred
grams to >1000 kg, each with its own unique anatomy and
physiology. Although specialists in equine surgery were the
fi rst to use diagnostic arthroscopy in horses as early as 1973
and equine surgeons were the fi rst to adopt surgical laparoscopy in the early 1990s, the use of MIS in other species
has lagged behind other fi elds. Small animals, e.g., dogs and
cats, can be safely anesthetized, recover quickly from open
surgery, rarely suffer from wound complications, and owners
have less concern for cosmetic outcome. The safety of laparoscopic procedures in animals is well accepted among both
large and small animal veterinarians. Several investigators
have demonstrated less postoperative analgesic requirements for dogs undergoing laparoscopic as compared to
open procedures [6–8]. Recent studies have shown that
small dogs undergoing laparoscopic ovariectomy recover
their pre -surgical activity levels more quickly than those
undergoing an open laparotomy [6]. However, even with
established safety and effi cacy and rapid recovery from MIS,
the apparent driving factor for adoption of MIS in small
animal veterinary medicine is that animal owners desire the
same level of care for their pet that they are able to obtain
for themselves. As more veterinarians receive postgraduate
training and purchase equipment, laparoscopic procedures
for routine operations are becoming more widely practiced;
however, it is not yet a standard of care in veterinary medicine as it is in human surgery.
To continue a contribution to NOTES development, and
to expand application of MIS in veterinary medicine, we and
others began to explore the feasibility of performing clinically relevant NOTES procedures in companion animals. We
Natural Orifi ce Translumenal Endoscopic Surgery (NOTES): Textbook and Video Atlas, First Edition. Edited by Anthony N. Kalloo, Jacques Marescaux,
Ricardo Zorron.
© 2012 John Wiley & Sons, Ltd. Published 2012 by John Wiley & Sons, Ltd.
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SECTION 3 Perspectives on NOTES
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did not presuppose that NOTES procedures would be widely
applicable for clinical use; rather, our goal was to compare
NOTES approaches to traditional techniques of open and
laparoscopic surgery in order to understand the potential
advantages of NOTES over other MIS approaches. Finally,
we wanted to study the learning curve associated with the
new techniques and explore the feasibility of performing the
techniques with conscious sedation, rather than general
anesthesia. This chapter summarizes the results of these
studies.
Advantages and disadvantages of NOTES
in animals
One of the primary advantages to NOTES in human medicine is improved cosmetic outcome from the lack of a skin
incision. Because animal skin is covered with an extensive
hair coat, except for exhibition animals, improving cosmetic
outcome by lack of scarring is not generally a goal in veterinary medicine. Procedures that promote a faster return to
the animal ’s pre -surgical activity level are of benefi t, especially in working animals and athletes. Procedures that minimize adhesion formation would be especially benefi cial for
horses because they frequently demonstrate colic behavior
as a result of internal adhesions. Wound infections occur in
veterinary medicine, with surgical site infections noted in
3.4% of dogs undergoing clean -contaminated surgical procedures [9]. Wound infections develop in 7.4 –37% of horses
undergoing midline celiotomy [10,11]. Incisional hernias
developed in 11% of horses undergoing midline celiotomy
[12]. In small animals, incisional hernias are rare and are
usually attributed to technical failure during wound closure.
Reducing pain at the incision site, with its attendant reduced
requirements for postoperative analgesia, promotes faster
return of intestinal mobility and eating is a theoretical
advantage in all species.
Since laparoscopic procedures require insuffl ation to
provide an optimal visual fi eld, the side effects are decreased
functional residual lung capacity and total lung capacity.
Increased intra -abdominal pressure, in combination with
general anesthesia, can impair venous return, reduce cardiac
output, and induce systemic hypotension that impairs renal
and vital organ perfusion. One of the proposed benefi ts of
NOTES is that lower insuffl ation pressures can potentially
be used, preserving total lung capacity and providing better
hemodynamic stability during anesthesia [13].
As for disadvantages of NOTES, equipment limitations
combined with anatomical variation in certain animals
present the fi rst challenge for wide utilization of NOTES in
veterinary medicine. The natural orifi ce must be of suffi cient
diameter to accept the endoscope and the endoscope length
must be able to reach internal structures. In cattle, for
example, a four -chambered stomach prevents using the
transgastric approach to access the abdominal cavity. The
entry site must be prepared suffi ciently to minimize introduction of microbes into the body cavity. Swine have a spiral
colon that is diffi cult to prepare adequately for NOTES procedures that involve transcolonic access. Apparently, the
microbial fl ora of the pig ’s stomach is also quite different
from that of the dog ’s stomach. As with human surgery, poor
visualization, and issues with navigation, maneuverability,
and grasping and/or tissue extraction are additional issues
that must be solved with technical improvements in equipment. Veterinary medicine and human medicine share a
common need to quickly address procedure -related complications such as bleeding and organ damage during NOTES
procedures.
Advanced skills in both endoscopy and surgery are
required for NOTES procedures and are addressed in human
surgery by experienced teams of surgeons and gastroenterologists. Because most veterinary internists lack the advanced
endoscopic skills of their human counterparts and, similarly,
many veterinary surgeons lack advanced laparoscopic skills,
the learning curves for NOTES techniques in veterinary
medicine are quite steep. The “totally” NOTES procedures
nearly always result in longer operative times, and our
studies have shown that transgastric access requires approximately 10 procedures to be performed by the same team
before approaching profi ciency [14] (Figure 20.1). As veterinarians transition to performing NOTES procedures on
client-owned animals, our recommendation is to perform
these studies under research protocols with signed owner
consent and utilize a means for safety monitoring.
Figure 20.1 Learning curve for canine NOTES oophorectomy. A
minimum of 10 surgical procedures were required for the operative time
to drop below 100 minutes, which is the upper value for the 95%
confi dence interval for predicted operative time. (Reproduced with
permission from Evaluation of the learning curve for natural orifi ce
translumenal endoscopic surgery: bilateral ovariectomy in dogs. Vet Surg
2011;40:140–50.)
216
Table 20.1 Instrumentation used in NOTES procedures in veterinary medicine.
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CHAPTER 20 NOTES Applications in Veterinary Medicine
Instruments Canine transgastric NOTES
oophorectomy
Endoscope Dual-channel therapeutic endoscope
(Olympus GIF 2T -160, Olympus America
Inc., Center -Valley, PA, USA)
Access
instruments
Grasping
forceps
Local
anesthesia
Coagulation
device
Closure
supplies
Laparoscopic
monitoring
Overtube (US Endoscopy, Mentor, OH, USA)
16 gauge intravenous catheter
0.035″ guidewire (Tracer
Wire Guide, Cook Medical, Bloomington,
IN, USA)
Balloon tipped through -the-scope catheter
(CRE™ Esophageal/Colonic Wire -guided
Balloon, Boston Scientifi c Corporation,
Natick, MA, USA)
Tripod grasping forceps (Polygrab ™ Tripod,
Olympus Endoscopy)
Laparoscopic spay hook (SPAY hook, Karl
Storz Veterinary Endoscopy, Goleta, CA,
USA)
NA 17 G endoscopic injection needle
Monopolar snare (AcuSnare ®; Cook
Medical)
T-fasteners swaged to 2 -0 nylon suture and
suture clip (Cook Medical)
NA NA Laparoscopy equipment (laparoscope, video
®
Metro Direct ™
Equine transvaginal NOTES
oophorectomy
Flexible endoscope (Olympus GIF
P-140 or GIF 2T -160)
15 mm diameter optical trocar
modifi ed to accept the fl exible
endoscope (Ethicon Endo Surgery, Cincinnati, OH, USA)
33 mm diameter Large -Port
assembly (LTK33, Ethicon
Endo-Surgery)
Laparoscopic claw grasping
forceps with 60 cm shaft length
(ARO910136BM, Arrow
Medical Supply, Inc.,
Libertyville, IL, USA)
(Lance-A-Lot, Mila International,
Inc., Erlanger, KY, USA)
2–10 mm bipolar sealing devices
(LIGASURE, Valley Lab, Boulder,
CO, USA) modifi ed to make
one instrument with a 60 cm
shaft length
#1 or #2 absorbable suture
material for vaginal closure
10 mm laparoscopic needleholders
with 45 cm shaft length
(V444-R, Endoplus, Inc., Buffalo
Grove, IL, USA)
Canine NOTES gastropexy
Dual-channel therapeutic endoscope
(Olympus GIF 2T -160)
Overtube (US Endoscopy, Mentor, OH, USA)
16 gauge intravenous catheter
0.035″/450 cm guidewire (Tracer
Direct ™ Wire Guide, Cook Medical)
Balloon tipped through -the-scope catheter
(CRE™ Esophageal/Colonic Wire -guided
Balloon, Boston Scientifi c Corporation)
NA
NA
Huibregtse triple lumen needle knife (Cook
Medical)
T-fasteners swaged to 2 -0 nylon suture and
suture clip (Cook Medical)
camera, light guide cable, insuffl ator,
insuffl ation tubing, CO
monitor)
10 mm blunt -tip trocar -cannula
®
Metro
tank, video
2
Instrumentation
The size of the animal will determine the diameter and
length of the scope needed, and the scope diameter will
determine the size of the accessory channel and the fl exible
endoscopic instruments needed for the procedure. Specifi c
instrumentation for selected veterinary NOTES procedures
is detailed in Table 20.1.
Dogs
For transgastric access, the 12.8 mm outer diameter dual channel scope works well for dogs weighing more than
15 kg. A mouth speculum or overtube facilitates introduction into the esophagus and prevents damage to the scope
if the animal becomes too light during the procedure. Basic
endoscopic accessories may include grasping forceps with
alligator -type jaws, teeth, or two - or three -prong jaws.
Snares are available in a variety of sizes ranging from 25 mm
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to 60 mm and in oval, hexagonal, and crescent confi gurations. An endoscopic needle -knife or sphincterotome are
needed if tissue cutting is anticipated and endoscopic scissors
are needed to cut suture. A method of achieving monopolar
coagulation is needed for dissection and hemostasis. The
0.035” guidewire and several types of over -the-wire disposable balloon dilators are available. A pressure -monitored
injection means is needed if balloons are to be used.
A means of closing the access site must be provided.
Sutures, staples, endoscopic clips or tacks, suturing devices,
T-fasteners and tissue anchors, rivets, bioabsorbable plugs,
and occlusion devices have been tried experimentally;
however, few devices are commercially available. Novel
techniques, such as gastropexy, submucosal tunneling, and
omental sealing have been used to achieve gastric closure in
experimental NOTES procedures; however, reliable gastric
closure remains a signifi cant unmet need in NOTES procedures [15].
A surgery table that tilts in four directions is necessary to
gain adequate exposure and ensure smooth transition of
procedural steps. A water -circulated heating pad or other
ancillary warming device will assist in maintaining core
body temperature during the procedure. If control of intra abdominal pressure is desired, an automatic insuffl ator and
CO
tanks are needed.
2
Figure 20.2 The prototype long bipolar sealing device made by
assembling two LIGASURE instruments into a single device. The handle
and shaft of one device were joined to the tip of a second one by
stainless steel couplings. The wiring to the bipolar electrodes was
extended and the entire unit was sealed with heat shrink tubing.
Horses
Transvaginal NOTES procedures in horses utilize large diameter endoscopes because greater light transmission is required
within the equine abdomen. The 12.8 mm dual -working
channel endoscope is ideal but not commonly available in
equine practices. Our studies used a 103 mm long, 9.8 mm
diameter endoscope with a single working channel of
2.8 mm diameter (Olympus
®
GIF P -140, Olympus America,
Inc., Center Valley, PA) for NOTES. Because of the heavy
weight of equine viscera, most commercialized endoscopic
instrumentation cannot be used for manipulating and grasping target organs during equine NOTES. Therefore, laparoscopic instruments are introduced alongside the endoscope.
Often in veterinary medicine, devices must be modifi ed to
achieve surgical goals. For the horse, instruments should
have a minimum shaft length of 60 cm. To achieve this, a
prototype bipolar vessel -sealing device was made longer by
cutting and joining two instruments together (Figure 20.2).
Pre -operative preparation
One of the concerns with translumenal access is the potential for introduction of pathogenic microorganisms into the
peritoneal cavity [16]. When investigators fi rst began to
perform NOTES procedures in swine, systemic antibiotics
were administered [1]. As infections were noted, efforts
were then directed toward sterilizing the instruments that
would be used during the procedure and instilling agents
into the stomach or colon for local cleansing [17]. It appears
that local lavage with Betadine or antibiotics is effective in
reducing infection rates in NOTES procedures [16,18]. In the
dog studies involving transgastric access, we have utilized
cephazolin 22 mg/kg administered intravenously every 90
minutes during the procedure and gastric lavage with a
10 min dwell time of 1 g cephazolin in 200 ml saline. We
have not utilized proton pump inhibitors as advocated by
others. In the horse, the vulva and vagina are prepared by
scrubbing with chlorhexidine gluconate.
Anesthesia and postoperative analgesia
Dogs
Laparoscopic procedures and all endoscopic procedures in
small animals are routinely performed under general inhalation anesthesia. The feasibility of using conscious sedation
for NOTES procedures in dogs is currently being explored.
Propofol as a standalone agent had not been used for endoscopic procedures in dogs, so we began by using propofol for
upper gastrointestinal endoscopic procedures in fi ve research
dogs (unpublished results). Following a loading dose, propofol was given intermittently to maintain moderate sedation. Supplemental oxygen was given by placing an oxygen
source at the side of the mouth. Each animal was monitored
with ECG, SpO
, end -tidal CO 2, blood pressure, heart rate,
2
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CHAPTER 20 NOTES Applications in Veterinary Medicine
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respiratory rate, and body temperature. Physiologic parameters remained within clinically acceptable ranges during
the 11 –15 minute gastroscopy procedure. There were no
instances of apnea. At the end of the procedure, recovery
was smooth and the dogs were able to walk within 10
minutes, and were considered completely recovered within
20 minutes. Based on these positive preliminary results, our
group has now successfully performed NOTES oophorectomy on nine dogs with propofol sedation without airway
control. The outcomes appear to be comparable to inhalant
anesthesia [19]. Dogs undergoing NOTES oophorectomy
procedures are usually given a single dose of hydromorphone 0.05 mg/kg postoperatively and monitored for pain.
In most cases, additional analgesia is not required.
Horses
Flank incisions in horses are routinely performed under
local anesthesia with the animal sedated, but standing, to
provide access to organs in the dorsal aspect of the abdomen.
The mares undergoing transvaginal NOTES procedures were
given an intravenous infusion of detomidine, an alpha -2
adrenoreceptor agonist, and butorphanol, an opioid analgesic. In order to provide further analgesia of the pelvic
and caudal abdominal organs, caudal epidural analgesia
with morphine can be administered. Additional intravenous
injections of detomidine and butorphanol are given, if there
is discomfort. With special care given to monitoring in our
studies, there were no falls, and all mares were able to walk
back to their stalls when the procedure was completed.
Postoperatively, horses are given fl unixin meglumine, a
non-narcotic, non -steroidal, analgesic agent with anti infl ammatory and anti -pyretic activity at a dose of 1.1 mg/
kg IV every 12 hours for 2 days following surgery.
instills CO 2 when the intra -abdominal pressure falls below
a pre -set level, usually 12 –14 mm Hg. Methods for safe
access to the abdominal cavity and creation of the optical
cavity in NOTES evolved from these techniques.
Transgastric access
The PEG technique was used to gain transgastric access to
the abdominal cavity. With increasing experience, the technique evolved over time. The exit site location on the
stomach was located on the dog ’s left side for the oophorectomy procedures and in the gastric antrum on the dog ’s right
side for the gastropexy procedures. In dogs, overinfl ation of
the stomach with air caused the stomach to rotate and the
exit site was more often located either on the posterior or
dorsal aspect of the stomach or near the greater curvature
and the location of the gastroepiploic vessels. With posterior
access, accidental entry into the omental bursa, the potential
space between the two leaves of the greater omentum, made
navigation with a fl exible endoscope quite diffi cult (Figure
20.3). The initial procedures involved using a dual -channel
endoscope, keeping the guidewire through one channel,
passing a needle -knife through the other channel, and using
it to make an incision in the gastric wall close to the
guidewire. Another technique utilized a sphincterotome
passed over the guidewire to enlarge the opening around it.
Both of these techniques could be associated with electrocautery injury to the abdominal wall or internal organs. As
the technique evolved, it was determined that by creating a
loop with the guidewire inside the abdominal cavity, the
balloon dilator could be passed over the guidewire and
rather easily positioned to transverse the gastric wall without
needing to enlarge the gastric opening around the guidewire.
Access
Endoscopists are very familiar with the techniques for percutaneous endoscopic gastric (PEG) tube placement and
using air to distend an organ for proper examination. Access
in the PEG procedure is gained by infl ating the stomach with
air via a fl exible endoscope, transilluminating the abdominal
wall, applying pressure with a fi ngertip, and observing it
with an endoscope. A catheter and suture or guidewire are
introduced percutaneously into the stomach at the safe site
and grasped with a snare passed through the accessory
channel of the endoscope. In laparoscopic procedures, access
is gained either by direct access using the open Hasson technique, or by insuffl ating the peritoneal cavity with gas,
usually CO
trocar is then inserted into the abdominal cavity at a safe
location and the residual cannula subsequently serves as a
port for introduction of the telescope. The pneumoperitoneum is maintained by an automatic insuffl ator, which
, to create an optical cavity. A safety -shielded
2
Figure 20.3 Endoscopic view of entry into the omental bursa, the
potential space between the two leaves of the greater omentum,
in the dog.
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3
1
2
Figure 20.4 Laparoscopic view of entry of the catheter into the
stomach during NOTES endoscopic gastropexy in the dog.
The 20 mm balloon dilator was then passed over the
guidewire and the balloon was infl ated to 6 atmosphere
pressure and held for approximately 2 minutes. As the
balloon was defl ated slight, the endoscope was advanced so
that it would follow the balloon into the abdominal cavity.
The balloon was then defl ated and withdrawn from the
scope, leaving the guidewire in place. An alternative to using
the looping technique is to use blind insertion of a Veress
needle to infl ate the abdomen with CO
and then using a
2
needle-knife to create the opening in the stomach at a safe
location [20].
Laparoscopic monitoring of gastric access may be used in
client-owned animals. In our studies, the primary camera
port was placed just below the umbilicus using the Hasson
technique. The abdomen was insuffl ated with CO
to
2
10 mmHg and a laparoscope was inserted. Light from the
endoscope inside the stomach was readily visualized. The
PEG technique was performed with a 5” long 19 gauge
catheter introduced through the body wall and into the
stomach at a predetermined site (Figure 20.4).
Transvaginal access
The fi rst procedures in horses were performed with blind
entry through the vaginal wall with the tip of a scalpel blade.
When this maneuver resulted in fatal hemorrhage from
laceration of a branch of the deep femoral artery in one
horse, the technique was changed so that abdominal access
could be performed more carefully. Laparoscopic monitoring
provided inadequate visualization for safe entry through the
vagina in the horse. An optical trocar was then modifi ed to
accept a fl exible endoscope for visualization during entry
through the vaginal wall (Figure 20.5). Following this, a
Seldinger technique was used to replace the 12 mm trocar,
Figure 20.5 An optical trocar (1) that was modifi ed to accept the
fl exible endoscope. Entry through the layers of the vaginal wall were
visualized during entry into the abdomen in the horse. The outer canula
of the trocar (2) and the transition from vaginal wall (3) to the yellow
color of abdominal adipose tissue is clearly seen.
1
3
2
Figure 20.6 Endoscopic view of the 33 mm port placed through the
colpotomy in the horse. The dorsal aspect of the vagina (1), the ventral
aspect of the vagina (2), and the external seal of the entrance to the
trocar (3) are identifi ed.
dilate, and then place a 33 mm trocar into the abdomen
through the colpotomy incision (Figure 20.6). The NOTES/
laparoscopic hybrid techniques for oophorectomy or ovariohysterectomy in dogs that utilize a transvaginal port for
removal of the uterus and ovaries are performed by introducing a 5 mm trocar through the vagina under laparoscopic
monitoring with the camera port placed at the umbilicus.
220
Figure 20.7 A Hasson trocar that will be placed for laparoscopic
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procedures in the dog. Two sutures are secured to the olive plug on the
trocar shaft.
Laparoscopic monitoring
For laparoscopy, many veterinarians prefer the open
approach as a safer means to gain entry to the abdominal
cavity. The Hasson technique uses a blunt trocar with an
olive plug inserted into the abdomen under direct visualization (Figure 20.7). A skin incision is made at or near the
umbilicus, the subcutaneous tissue is excised to expose the
external abdominal fascia, and a small midline incision is
made through the linea alba. Sutures are placed on each side
of the incision, the trocar is inserted, and the sutures are tied
to the olive plug of the trocar. The insuffl ation tubing is
attached to the trocar and the abdominal cavity is automatically insuffl ated with CO
to 10 mmHg to provide a viewing
2
cavity in which to monitor the subsequent procedure. At the
end of the procedure, the trocar is removed, air is allowed
to escape, and the abdominal fascia, subcutaneous tissue,
and skin are closed with sutures.
Insuffl ation
Although CO 2 has been used to create pneumoperitoneum
in both human and veterinary laparoscopic surgery
for many years and is relatively quickly absorbed and
excreted, investigators are now taking a second look at air
insuffl ation because air can be manually instilled through
the fl exible scope in NOTES procedures [21]. CO
tate visceral surfaces and absorption can possibly lead to
hypercapnia, sympathetic stimulation, vasodilation, hypertension, tachycardia, and arrhythmias. Previous studies have
demonstrated that CO
is associated with less peritoneal
2
infl ammatory response than room air [22,23]. Air may
support combustion when lasers or electrocautery are used.
may irri-
2
CHAPTER 20 NOTES Applications in Veterinary Medicine
At least one study has compared air to CO 2 for NOTES procedures and found little difference in visualization of organs
and hemodynamics [24]. Peak intra -abdominal pressures
with hand -activated on -demand insuffl ation with air are
higher than with regulated CO
[25,26].
2
Dogs
Our initial studies used on -demand air insuffl ation and
overdistention of the abdomen was frequent. To relieve
pressure, a 19 gauge catheter was placed percutaneously. If
the catheter was dislodged, the air then dissected into the
subcutaneous space through the catheter puncture sites,
resulting in signifi cant subcutaneous emphysema. We then
began using pressure -regulated CO
, rather than, or in addi-
2
tion to, air. Intra -abdominal pressures were then more
closely monitored by using the insuffl ator alarm to indicate
pressures exceeding the pre -set threshold. We rarely have
severe postoperative subcutaneous emphysema and there is
fast resolution of emphysema that does develop. However,
controlled studies monitoring peritoneal infl ammation following insuffl ation with air and CO
or combinations in
2
NOTES procedures in dogs remain to be completed.
Horses
With the transvaginal approach in horses, it is usually not
necessary to use a method for controlled pneumoperitoneum as there is adequate visualization with on -demand
insuffl ation of room air. It is unknown which gas incites less
peritoneal infl ammatory response in the horse as there have
been no comparative studies to date.
Exposure and navigation
Dogs
The oophorectomy procedure requires both working channels, so the endoscope is removed, taken off the guidewire,
and replaced alongside the guidewire into the abdominal
cavity. Considerable endoscopic skill is required for reintroduction of the endoscope into the abdominal cavity, as the
gastric infl ation is lost and the endoscope usually has to be
partially retrofl exed to enter the opening. During the gastropexy procedure, the guidewire is left in the working
channel. The guidewire is then used to pull the endoscope
up to the anterior abdominal wall so that the abdominal
musculature can be incised to prepare the site for gastropexy
(Figure 20.8). During this maneuver, the endoscopist fi xes
the guidewire at the accessory channel exit and traction is
applied to draw the tip of the endoscope toward the abdominal wall. This maneuver gives some rigidity to the endoscope
and helps to keep the abdominal wall incisions centered
around the guidewire.
While a tilting table allows the use of gravity for exposure
of internal organs, maintaining ovarian exposure with
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Figure 20.8 Laparoscopic view of a series of incisions in the peritoneum
of the dog in preparation for the gastropexy procedure.
Figure 20.9 Endoscopic view of the ovary suspended from the body
wall with the electrocautery snare in position below the ovary.
Figure 20.10 The laparoscopic spay hook has a weighted handle that is
used to retain the hook in place while suspending the ovary during
oophorectomy procedures.
limited numbers of instruments is diffi cult. Recently, we
began using a percutaneous suspension technique for the
ovary (Figure 20.9). A large needle or laparoscopic spay
hook (Karl Storz Veterinary Endoscopy America, Goleta,
CA) is placed through the abdominal wall (Figure 20.10).
When the needle enters the abdominal cavity, the ovary is
draped over the tip and the needle is then rotated into the
abdominal wall. Traction can then be applied to lift the
abdominal wall and ovary to further improve exposure.
Horses
A fasting regimen prior to surgery is absolutely required to
decrease the intralumenal volume and motility of loops of
small intestine. Visualization of the ovary can be signifi cantly impaired if loops of bowels are present in the caudal
abdomen, which render the procedure long and diffi cult to
complete. The 33 mm port allows a long grasping instrument
to be inserted beside the endoscope to aid in retraction and
exposure of abdominal organs.
Closure
Closure of the access site remains the most challenging
aspect of NOTES procedures in veterinary medicine, primarily due to the lack of commercially available devices. Tissue
apposition, prevention of infection, and sealing of the
opening against leakage are critical factors in the healing of
incisions.
Dogs
Our studies utilized pairs of T -fasteners for the transgastric
closure and the outcomes have been favorable. The omentum
appears to play a role in sealing the incisions. Despite considerable experience with using the T -fastener device, the
time required for gastric closure accounts for a major portion
of overall operative time. One of the limitations to the use
of T -fasteners is that the tip may incorporate tissue on the
outside of the stomach if they penetrate too deeply during
deployment. Our studies have utilized a cap on the end of
the endoscope to help avoid injury to adjacent tissue (Figure
20.11). Judging by early assessment of histologic healing and
postoperative outcomes, the closure is secure; however,
others have found that clips may result in a better histologic
healing [27]. Given the adverse clinical consequences of
222
Figure 20.11 A cap on the end of the endoscope is designed so that
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as the needle is advanced from the working channel, it is deployed in
the center of the cap.
gastric leakage, more studies are needed to document the
safety of this device and technique before widespread use in
NOTES procedures. The transvaginal access site is not closed
in dogs. Bleeding has been noted in a few animals in the
postoperative period.
Horses
The size of the equine vagina permits manual suturing of
the colpotomy using laparoscopic needle holders. A single
cruciate suture of absorbable suture material is placed under
endoscopic guidance and the knots are tied extracorporeally
and advanced to the operative site.
Complications
In veterinary medicine, the frequency and severity of various
complications related to minimally invasive surgery has not
been studied. However, it is reasonable to expect that complications will occur with NOTES. Avoiding complications
starts with knowing how and why they occur. Iatrogenic
trauma during access procedures can cause injury to major
vessels, underlying organs, or the abdominal wall [28]. In
our studies, issues with insuffl ation can lead to subcutaneous emphysema or inappropriate insuffl ation of the omental
bursa. In NOTES, technical limitations of a two -dimensional
view may occur more often with coaxial maneuvers. Surgeons may have less familiarity with endoscopic equipment,
and fl exible endoscopic procedures present a more restricted
range of motion and less tactile feedback to the operator.
Inability to obtain a clear view of the operative site can be
caused by equipment limitation or malfunction and is a
reason for conversion to an open procedure. Minor bleeding
can be diffi cult to control and obscures visibility. By pre operative preparation, close monitoring, ideal positioning,
CHAPTER 20 NOTES Applications in Veterinary Medicine
wide surgical preparation, proper instrument care and use,
proper technique, and proper training of the operating room
staff, many complications can be avoided or minimized.
Veterinary procedures
Canine transgastric NOTES oophorectomy
Indications
Oophorectomy is performed for elective sterilization to
prevent reproductive cycling and associated behavior
changes. When both ovaries are completely removed, studies
have shown no evidence of infection in the remaining
uterus or any other complications that occur at a higher rate
than when total ovariohysterectomy is performed.
Pre-operative preparation and anesthesia
Animals are fasted for 12 to 20 hours but given access to
water. A non -steroidal anti -infl ammatory drug is given subcutaneously for analgesia and the animal is given a general
anesthetic. Usually, intravenous propofol is given for anesthetic induction, followed by endotracheal intubation and
maintenance anesthesia with isofl urane and oxygen. Intravenous fl uids are given and the animal is placed on a
warming blanket, and monitored with indirect blood pressure, SpO
, end -tidal CO 2, electrocardiogram, and tempera-
2
ture probe. The abdomen is prepared for aseptic surgery. A
peri-operative antimicrobial is given every 90 minutes. The
overtube is placed. Following endoscopic examination and
cleansing of residual food particles, an antimicrobial, such
as cefazolin, 1 g in 200 ml saline, is instilled into the stomach
and allowed to remain for 10 minutes. A diagram of the OR
set-up is given in Figure 20.12.
Technique
A standard PEG technique is used to introduce a 0.035”
guidewire through a 16 gauge catheter from the animal ’s
left side (Figure 20.13). A balloon -tipped through -the-scope
catheter is introduced over the guidewire to traverse the
stomach wall. The balloon is infl ated to 6 atmospheres pressure for approximately 2 minutes to dilate the opening in
the stomach to 2 cm around the guidewire (Figure 20.14).
The balloon and endoscope are then passed into the abdominal cavity. The balloon is then defl ated and withdrawn and
the endoscope is removed and reinserted beside the
guidewire into the abdominal cavity. To provide an adequate
optical cavity, air or CO
is instilled. For access to the left
2
ovary, the table is tilted to the right. For a “totally NOTES ”
oophorectomy (meaning that no supplemental laparoscopic
ports are used), each ovary is elevated with grasping forceps
through a monopolar snare. Alternatively, the ovary can be
suspended from the body wall by a large hook or needle
placed percutaneously (Figure 20.9). Energy is applied to the
snare as it is closed and ultimately transects the tissue. The
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SECTION 3 Perspectives on NOTES
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Figure 20.12 Operative set -up for canine NOTES procedures showing the position of the patient, anesthesia machine, endoscopic tower, and
laparoscopic tower, if used for monitoring.
Figure 20.13 The guidewire being introduced through the scope in the
PEG technique.
ovary is then grasped with both the snare and the endoscopic forceps and withdrawn with the endoscope. After
examining the ovary to ensure complete removal, the endoscope is reintroduced and the surgical site is inspected to
ensure hemostasis. To access the right ovary, the table is
tilted left. The endoscope is passed and retrofl exed cranially
from the right inguinal area to visualize the right ovary
(Figure 20.15). Ligation and transection of the right ovary
with the monopolar snare are performed and the ovary and
endoscope are removed. The guidewire is left in place during
the procedure to assist in visualizing the gastric incision.
The gastrotomy is closed with two sets of T -fasteners positioned at 12 and 6 o ’clock and 3 and 9 o ’clock, each held
together by a suture clip. A beveled cap is secured to the
224
Figure 20.14 Endoscopic view of over -the-wire balloon catheter being
used to dilate the gastrotomy incision.
outside of the gastroscope and the scope is passed into the
stomach. A T -fastener is loaded into a delivery device and
passed through the working channel of the endoscope so
that the tip is visualized inside the cap. The gastrotomy is
identifi ed by the guidewire and the cap is positioned on
gastric mucosa adjacent to the incision. Vacuum is applied
to pull gastric mucosa into the cap. The needle is quickly
advanced into the gastric submucosa and the T -fastener is
deployed. The tissue is inspected as the vacuum is released
and a slight tug is applied to ensure that the T -fastener is
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