The Laryngoscope
Lippincott Williams & Wilkins, Inc.
© 2005 The American Laryngological,
Rhinological and Otological Society, Inc.
Transoral Robotic Surgery: Supraglottic
Laryngectomy in a Canine Model
Gregory S. Weinstein, MD; Bert W. O’Malley, Jr., MD; Neil G. Hockstein, MD
Objectives/Hypothesis: To develop a technique for
computer enhanced robotic transoral supraglottic
partial laryngectomy in the canine model. Study Design: Surgical procedure on the larynx in a canine
model with a commercially available surgical robot.
Methods: With use of the da Vinci Surgical Robot (Intuitive Surgical, Inc., Sunnyvale, CA), the supraglottic
partial laryngectomy was performed on a mongrel
dog that had been orotracheally intubated using general anesthesia. The videoscope and the 8 mm endeffectors of the robotic system were introduced
through three ports, transorally. The surgical procedure was performed remotely from the robotic system
console. The procedure was documented with still
and video photography. Results: Supraglottic partial
laryngectomy was successfully performed using the
da Vinci Surgical Robot, with 8 mm instrumentation.
The robotic system allowed for celerity and accuracy
secondary to findings specific to the surgical approach, including excellent hemostasis, superb visualization of the operative field with expeditious identification of laryngeal submucosal soft tissue and
skeletal landmarks, and multiplanar transection of
tissues. In addition, the use of the robotic system also
was found to have technical advantages inherent in
robotic surgery, including the use of “wristed” instrumentation, tremor abolition, motion scaling, and
three-dimensional vision. Conclusions: The da Vinci
Surgical Robot allowed for successful robotic transoral supraglottic partial laryngectomy in the canine
model. Key Words: Robotic, endoscopic, minimally
invasive surgery, microsurgery, larynx, partial laryngectomy, laryngeal cancer, da Vinci, transoral robotic
surgery (TORS).
Laryngoscope, 115:1315–1319, 2005
The authors wish it to be known that, in their opinion, all three
authors should be regarded as joint first authors.
From the Department of Otorhinolaryngology—Head and Neck Surgery, The University of Pennsylvania, Philadelphia, Pennsylvania, U.S.A..
Editor’s Note: This Manuscript was accepted for Publication May 10,
2005.
Send Correspondence to Dr. Gregory S. Weinstein, Professor and
Vice Chairman, Department of Otorhinolaryngology—Head and Neck Surgery, 5 Ravdin, University of Pennsylvania Health System, Philadelphia,
PA 19104, U.S.A. E-mail: [email protected]
DOI: 10.1097/01.MLG.0000170848.76045.47
Laryngoscope 115: July 2005
INTRODUCTION
The surgical management of supraglottic carcinoma
has evolved from the exclusive use of total laryngectomy
in the 19th century, to the use of open supraglottic partial
laryngectomy for selected cases in the mid to late 20th
century, to the use of transoral laser supraglottic partial
laryngectomy for selected cases in the late 20th and early
21st century. Each subsequent surgical technique was
functionally superior to its predecessor. The open supraglottic partial laryngectomy was superior to the total laryngectomy in allowing the surgeon to preserve enough of
the larynx to perform a temporary tracheostomy and feeding tube, thus avoiding a permanent tracheostoma. The
transoral laser supraglottic partial laryngectomy was superior to the open supraglottic partial laryngectomy in
that it allowed most patients to avoid even a temporary
tracheostomy and shortened the time course of swallowing
rehabilitation.1 In an effort to build on the foundation
created by the pioneers of transoral laser supraglottic
partial laryngectomy, we decided to consider the application of the da Vinci Surgical Robot (Intuitive Surgical,
Inc., Sunnyvale, CA) to transoral supraglottic partial laryngectomy in the canine model.2
Robotic surgery has thus far found its major niche in
cardiac and urologic surgery, with approximately 10% of
radical prostatectomies performed in the United States in
2004 being robotically assisted.3,4 Among the other areas
that have been developing robotic techniques have been
bariatric and gynecologic surgery.5,6 Research using the
da Vinci Surgical Robot (Intuitive Surgical, Inc., Sunnyvale, CA) in the area of otolaryngology– head and neck
surgery has been in the area of surgery of the neck, including procedures such as selective neck dissection.7,8
The da Vinci Surgical Robot consists of a master control
and a remote-manipulator station in which there is a
surgeon’s console (master-control) and a robotic cart
(remote-manipulator), which is next to the patient, with
three arms, two placed laterally for the instruments and
the middle one for the endoscopic camera. Hockstein et
al.,9,10 from the Department of Otorhinolaryngology–
Head and Neck Surgery at the University of Pennsylvania, have recently demonstrated the feasibility of using
robotic surgery in mannequin and human cadaver models
for transoral laryngopharyngeal dissections. We present
the results of a pilot study of the first transoral robotic
Weinstein et al.: Transoral Robotic Surgery
1315
surgery (TORS) supraglottic partial laryngectomy in the
canine model.
MATERIALS AND METHODS
The procedure was performed in accordance with the “Guide
for the Care and Use of Laboratory Animals.”11 The protocol was
approved by the institutional animal care and use committee.
One mongrel dog weighing 28.20 kg was used in this study.
The dog underwent TORS supraglottic partial laryngectomy using the da Vinci Surgical Robot. The preanesthesia used for the
dog was intramuscular atropine sulfate (AmVet, Neogen Corporation, Lexington, KY) then a mixture of tiletamine HCL and
zolazepam HCL (Telazol, Fort Dodge Animal Health, Fort Dodge,
IA) and xylazine base (Tranquived Injection, Vedco Inc., St. Joseph, MO) intramuscularly. For induction, propofol (Propoflo,
Abbott laboratories, N. Chicago, IL) was used followed by orotracheal intubation with a number nine cuffed endotracheal tube
and with maintenance inhalation anesthesia with isoflurane
(Isosol, Rhodia Organique Fine, Ltd., Avonmouth, Bristol, UK).
Paralysis was achieved with intravenous pancuronium bromide
injection (Baxter, Irvine, CA). Positive pressure ventilatory support was achieved throughout the procedure with an Ohmeda
7000 Ventilator, (Ohmeda BOC Health Care, Madison, WI). Monitoring of cardiac status and oxygenations was performed using a
Datex-Ohmeda S/5 (Datex-Ohmeda Division, Instrumentarium
Corp, Helsinki, Finland). The dog’s blood pressure was monitored
throughout the procedure and found to be approximately 100
systolic over 50 diastolic. At the end of the procedure, the animal
was killed.
TORS Supraglottic Partial Laryngectomy
Technique
The procedure was performed by the first author (G.S.W.)
and concurrently evaluated by the coauthors (B.W.O., N.G.H.).
The dog was positioned in the supine position, and the operating
room table was rotated 30 degrees relative to the robotic cart, as
previously described.10 The tongue was retracted using 2– 0 silk
sutures passed through the tongue and attached to a suspension
apparatus. The surgical technique that was used was a modification of the transoral supraglottic partial laryngectomy described
by Rudert et al.1 Although Rudert et al. described using a laryngoscope, an operating microscope, and a CO2 laser, none of these
were used in the current study. Visualization of the laryngopharynx was achieved with a 30 degree, upward facing, threedimensional endoscope inserted transorally in the midline, and
the ports for the 8 mm robotic instrumentation were introduced
transorally into the laryngopharynx at approximately 30 degree
angles from the axis created by the midline position of the endoscope. The surgeon was seated at the surgical console, approximately 10 feet from the surgical table and robotic cart. The
surgeon viewed the operative field by way of a three-dimensional
image while his hands held the master controls at a comfortable
distance below the display. The procedure was documented with
both still and video photography.
The first step in the surgical procedure is the vertical division of the epiglottis (Fig. 1). The incision is followed laterally to
find the hyoid bone. The excision is carried inferiorly along the
thyrohyoid membrane until the superior aspect of the thyroid
cartilage is identified (Fig. 2). The entirety of the preepiglottic
space is dissected from the inner aspect of the thyrohyoid membrane and thyroid cartilage from superior to inferior toward the
anterior commissure and lateral angle of the ventricle. Although
Rudert et al. recommend resection of the suprahyoid portion of
the epiglottis when necessary for visualization, this is not needed
for the canine TORS supraglottic partial laryngectomy. The dissection is continued laterally through the pharyngoepiglottic fold.
Laryngoscope 115: July 2005
1316
Fig. 1. The first step in the surgical procedure is the vertical division
of the epiglottis using the cautery with spatula, which is a small
monopolar cautery unit (instrument on the right side of the surgical
field).
In this area, the superior laryngeal vessels may be cauterized or
ligated with vascular clips or both. The incision is carried inferiorly through the aryepiglottic fold, just anterior to the arytenoids.
The false cord is then transected just anterior to the arytenoids.
The final transection is made through the lateral aspect of the
laryngeal ventricle, and the procedure is repeated on the opposite
side, leaving a wound above the true cords, with the arytenoids
and pyriform sinuses left intact (Fig. 3), resulting in a bisected
surgical specimen (Fig. 4).
Instrumentation Details
An 8 mm instrumentation was used. The instrument entering the laryngopharynx from the left-side port was the precise
bipolar, which is a triangular shaped forceps that allows the
double feature of grasping, and, when needed, functions as a
bipolar forceps (Fig. 4). The plan was to only use these bipolar
forceps for tissue traction with their low-profile serrations but
also to use them for hemostasis. The instrument initially used by
Fig. 2. The excision is carried inferiorly along the thyrohyoid membrane until the superior aspect of the thyroid cartilage is identified.
Weinstein et al.: Transoral Robotic Surgery
Fig. 3. View of the operative field after the resection.
way of the right sided port was the cautery with spatula, which is
a small monopolar cautery unit (Figs. 3, 4, and 5). The cautery
with spatula was replaced with the permanent cautery hook
during the resection of the first half of the procedure (Fig. 4). The
tips of the monopolar cautery could be cleaned of debris either
with the forceps in the opposite hand or by having an assistant
wipe the tips with a gauze pad. The monopolar cautery unit Force
FX (Valley Lab, Boulder, CO) was set to “cautery blend,” initially
at 25, and was then increased to 30. A harmonic scalpel was also
available but not used because this instrument is not “wristed”
and therefore had limited utility.
Fig. 5. The surgeon’s hands holding the master controls at a
comfortable distance below the display while surgeon is seated at
the surgical console.
RESULTS
Operative Time
The operating room setup and animal positioning
was accomplished in under 30 minutes. The length of time
of the resection was 20 minutes, 57 seconds.
Hemostasis
Both the cautery with spatula and the permanent
cautery hook transected mucosa, fat, and muscle with
minimal residual bleeding and minimal residual char. The
need for additional cauterization of either mucosal or submucosal soft tissue bleeders was minimal. There was no
need to suction blood to improve visualization, nor was
there a need to use suction cautery to achieve hemostasis.
A suction catheter was used to evacuate smoke created by
the monopolar cautery.
Visualization of Operative Field
Fig. 4. The precise bipolaris a triangular shaped forceps that allows
the double feature of grasping and, when indicated, functions as a
bipolar forceps (inferior). Resected halves of the supraglottic partial
laryngectomy (middle). The permanent cautery hook is small blunt
ended hooked monopolar cautery unit (superior).
Laryngoscope 115: July 2005
The TORS technique allowed for excellent visualization of the operative field. The use of a 30 degree, threedimensional endoscope allowed the surgeon excellent
depth perception during the resection. The ability to move
the endoscope farther or closer from the tissues being
resected allowed for excellent magnification on close-up
views. The combination of foot petal and hand motions at
the surgical console allows for changing the position of the
tip of the endoscope to the right, left, up, or down in an arc
of rotation, which is limited only by the size of the opening
in the oral cavity rather than by the limitations of line of
sight that are inherent when using laryngoscopes in traditional microscopic laryngeal surgery. The light source
provided excellent and consistent illumination for all angles of view. All key surgical landmarks including the
epiglottis, hyoid bone, thyroid cartilage, pharyngoepiglottic folds, pyriform sinuses, false cords, arytenoids, vocal
cords, and laryngeal ventricle were clearly and readily
identifiable.
Weinstein et al.: Transoral Robotic Surgery
1317
Multiplanar Transection of Tissues
An articulating joint is present just proximal to the
end of the forceps and the cautery unit (Figs. 1, 2, and 3).
Movement around this joint corresponds to the wrist
movements of the surgeon at the surgical console (Fig. 5).
This allows the surgeon to use the tip or entire surface of
the cautery to cut in the axial or sagittal or coronal plane,
or any combination of the three planes, with great accuracy. The permanent cautery hook could be placed under
structures such as the false cord and could then be used to
cut the tissues from a caudal to cranial direction. Caudal
to cranial transactions could also be made with the cautery with spatula.
Impact of Technical Advantages Inherent in
Robotic Surgery on the TORS Supraglottic
Partial Laryngectomy
The well-established advantages of robotic surgery,
noted in the literature, include the use of “wristed” instrumentation, tremor abolition, motion scaling, and threedimensional vision. All of these were found to facilitate the
surgical procedure.
DISCUSSION
The transoral laser supraglottic partial laryngectomy
is functionally superior to open supraglottic partial laryngectomy because, in almost all cases, it obviates the need
for a tracheostomy and shortens the period of postoperative dysphagia.1 Robotic surgery offers several advantages
to the surgeon including three-dimensional visualization,
tremor filtration, and wristed instrumentation. The major
potential necessity for TORS, if it is to become a clinically
viable approach, is the availability of robotic systems,
which at present are limited to 205 systems in 34 states.
The differences between this pilot study of TORS supraglottic partial laryngectomy and the transoral laser supraglottic partial laryngectomy are outlined in Table I.
The experimental data on wound healing and tissue
injury when comparing monopolar electrocautery with
CO2 laser, and its impact on clinical management, remains inconclusive. Carew et al.,12 in a study that evaluated the impact of different types of oral tongue incisions
in rats, reported that the depth of wound healing was
greater with the CO2 laser than with the electrocautery
unit. Liboon et al.13 noted that the acute width of injury
for incisions was greater for wounds made with electrosurgery than with the CO2 laser in a porcine oral mucosal
model. However, by 3 days, Liboon et al. reported no
statistical difference in inflammation between the CO2
laser and the electrocautery unit.13 Finally, both epithelialization as well as formation of granulation tissue was
similar for electrosurgery and CO2 laser at 4 weeks.13
The problem with studies comparing similar linear
incisions in animal models is that they may not accurately
reflect clinical practice. In fact, the laser cuts through
tissue at a much slower rate than does the monopolar
cautery unit, and it takes many passes with a laser to
make the same incision that can be made with a single
swift cut with the robotic cautery arm. For instance, using
the laser to make a vertical midline transaction through
the epiglottis is time consuming and requires multiple
passes with the laser and typically a significant amount of
suction monopolar electrocautery, whereas vertical transaction in the canine model required fewer passes with the
electrocautery unit. It is not clear whether multiple laser
passes create more or less tissue damage than do fewer
passes with the electrocautery.
Clinical data concerning the use of monopolar electrocautery in the supraglottis is sparse. Oluwasmni and
Mal14 performed monopolar diathermy partial epiglottectomy in four patients because of snoring or sleep apnea
and found no significant problems with bleeding or airway
edema, and three patients were discharged on the first
postoperative day and one on the second postoperative
day. Although these authors did suggest performing total
epiglottectomy using monopolar diathermy was safe, from
the perspective of bleeding and airway swelling, to date
this has not been reported.
Suction monopolar cautery has been used, as indicated above, close to the glottis or the arytenoids to control
bleeding during transoral laser endoscopic supraglottic
partial laryngectomy without ill effect.15 Although the dog
in this procedure was killed after TORS supraglottic partial laryngectomy, gross examination of the tissues after
the resection indicated minimal edema and minimal char,
TABLE I.
Differences between Transoral Robotic Surgery (TORS) Supraglottic Partial Laryngectomy and Transoral Laser Supraglottic
Partial Laryngectomy.
TORS Supraglottic Partial Laryngectomy
Transoral Laser Supraglottic Partial Laryngectomy
Instrumentation to
expose the larynx
McIvor or Dingman mouth gag allows for wide mobility
of robotic arms
Nature of resection
Multiplaner transection using instruments that mimic
normal hand movements, including caudal to cranial
transection
Tip of endoscope inside the patient
Surgeon may repeatedly and instantaneously reposition
the robotic arms to change viewpoint during the
procedure
Supraglottic laryngoscopy with or without bivalving
apparatus limits the “line of sight” from the
microscope
“Line of sight” resection with carbon dioxide laser;
no caudal to cranial resection possible; no axial
plane resection possible
Lens of microscope distant from the patient
Surgeon must retract tissues to keep them within the
“line of sight” of the microscope and laser or
remove and reposition laryngoscope to modify
“line of sight”
Carbon dioxide laser
Point of visualization
Exposure of primary site
Surgical incisions
Monopolar diathermy
Laryngoscope 115: July 2005
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Weinstein et al.: Transoral Robotic Surgery
with normal appearing mucosa at margins of resection
(Fig. 5).
8.
CONCLUSIONS
The da Vinci Surgical Robot allowed for successful
completion the TORS supraglottic partial laryngectomy in
the canine pilot study. Further study is indicated.
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