Endoscopy In Small Animal Medicine And Surgery

Compendium April 2000

20TH ANNIVERSARY

EMERGING TECHNOLOGY

Small Animal/Exotics

V

Endoscopy in Small Animal Medicine and Surgery Elizabeth A. Carsten, DVM, Diplomate, ACVIM, and Stephen D. Gilson, DVM, Diplomate, ACVS Sonora Veterinary Specialists Phoenix, Arizona

E

ndoscopy refers to fiberoptic, video, and rigid endoscopy. The principle of total internal reflection in fiberoptics allows light to be transmitted through a flexible system for both illumination and visualization. A large number of very fine, coated glass fibers are combined to form a flexible bundle that is used for image transmission and illumination. Video endoscopes replace the image bundle with an electronic signal transmission system; the image is “read” by a video chip and displayed on a monitor. Special video cameras (endocouplers) can also be attached to fiberoptic endoscopes to produce a combination system for video display and recording. Flexible fiberoptic and video instruments are used to evaluate the respiratory, gastrointestinal (GI), and urogenital tracts. Rigid endoscopes use a noncoherent fiber light transmission bundle for illumination but a series of glass lenses for optical transmission. Rigid endoscopes are used for rhinoscopy, arthroscopy, cystoscopy, laparoscopy, and thoracoscopy procedures.

History Endoscopy was first described in the early 1800s, but advances were

not made in the discipline until the late 1800s, when optical lenses were incorporated into viewing devices and incandescent bulbs were invented.1 Laparoscopy was pioneered by Kelling in 1902 when he inserted a cystoscope into the abdomen of a dog.2 Thoracoscopy quickly followed in the early 1900s when a cystoscope was used in humans in an attempt to break down adhesive tuberculosis lesions.3 In 1987, Mouret performed the first laparoscopic cholecystectomy; an explosion of simultaneous work developing endless endoscopic surgical techniques and equipment soon followed.4

Uses When using flexible endoscopes, gastroduodenoscopy and colonoscopy allow direct examination and mucosal biopsy of the GI tract from these areas and in many cases, retrieval of gastric foreign bodies without the need for invasive exploratory laparotomy. Endoscopy is considered more reliable than is barium series for diagnosing esophagitis, chronic gastritis, GI ulceration, gastric neoplasia, inflammatory bowel disease, and colitis. Biopsy samples obtained with endoscopy are associated with less morbidity and thus should be obtained regardless of gross mucosal appearance. The most significant limitation of GI endoscopy is the inability to examine the entire length of intestine (especially the jejunum and ileum). Flexible endoscopic bronchoscopy is one of the best diagnostic tests for evaluating canine and feline lower air-

way disease. No other procedure allows direct evaluation of both anatomic and functional aspects of the airways while simultaneously allowing collection of samples. Before proceeding with the bronchoscopy, thoracic radiographs should be obtained to fully evaluate all thoracic structures (heart, pleural space, chest wall, lungs, airways) and help identify areas of concern to evaluate during the bronchoscopy. Similarly, rhinoscopy is a noninvasive technique that is considerably less traumatic than surgical exploration but allows direct visualization of and sample collection from the nasal cavity, nasal turbinates, and nasopharynx. Occasionally, the frontal sinuses can be examined through the nasal cavity, or they can be accessed directly by trephining a hole in the outer table of the frontal bone. Typically, a flexible endoscope is used to evaluate the nasopharynx, and rigid endoscopes are used to evaluate the rest of the nasal cavity. Rhinoscopy is essential to diagnosing nasal disease but cannot always be relied on to provide a diagnosis by itself. Successful diagnosis of chronic nasal disease is considerably enhanced by taking a thorough and systematic approach centered around effective rhinoscopic examination. Depending on the size and sex of patients, both small flexible fiberoptic and rigid endoscopes are used for cystoscopy and vaginoscopy. The advantages of using cystoscopy instead of other diagnostic techniques are many: It provides minimally invasive direct visualization of the vagina, urethral

Small Animal/Exotics

opening, urethra, bladder, and ureteral openings. Visualization of these structures, even where accessible by surgery, is superior with cystoscopy because of the magnification provided and elimination of distortion. Arthroscopy is a minimally invasive technique that evaluates soft tissue structures and joint cartilage not visible on radiographs. In addition, some structures can be visualized better with arthroscopy than with surgery. Decreased morbidity and shortened recovery times are two advantages of arthroscopy over arthrotomy. Thus arthroscopy is rapidly becoming the diagnostic tool of choice in evaluating shoulder lameness. Disadvantages include its limitation during diagnostic and corrective surgical procedures in small patients. Although all these procedures are widely used in veterinary medicine, laparoscopic and thoracoscopic techniques are more recent advances. Laparoscopy is a minimally invasive method for evaluating intraabdominal structures. Organs that can be visually inspected and/or biopsied include the liver, gallbladder, spleen, kidneys, urinary bladder, prostate, vas deferens, ovaries, uterus, adrenal glands, stomach, pancreas, small and large intestine, lymph nodes, and peritoneal surfaces. At this time, laparoscopy is used most frequently in veterinary medicine to obtain hepatic and renal biopsy samples. The greatest advantage of laparoscopy compared with exploratory laparotomy is the lower morbidity and mortality because trauma to the patient is minimized. However, the potential benefits for veterinary patients are only beginning to be explored. Many laparoscopic techniques currently being used in human medicine (i.e., cholecystectomy, intestinal biopsy, gastrotomy/enterotomy, GI resection and anastomosis, gastrostomy/enterostomy tube placement, gastropexy) are being evaluated for their applicability in veterinary patients. The main disadvantage of laparoscopy may be the inabili-

Compendium April 2000

ty of veterinarians to evaluate deeper parenchymal lesions. With expanded efforts to explore minimally invasive surgical techniques, thoracoscopy has stimulated renewed interest in human thoracic medicine and surgery. The use of thoracoscopy has been limited to a few veterinarians and referral centers, with only a few reports of thoracoscopy in the veterinary literature. The technique is considerably less invasive than is traditional thoracotomy and has much lower morbidity and mortality. The view obtained with thoracoscopy is often better than that obtained with traditional thoracotomy because any structure within the thorax can be visualized and is magnified by the endoscope. In veterinary medicine, thoracoscopy has been used to diagnose intrathoracic pathology (especially hilar and mediastinal masses), evaluate fluid loculation versus solid masses, and treat malignant pleural effusions and pericardial diseases.1 In human medicine, thoracoscopy has also been used for general thoracoscopic exploration, staging of neoplasia, assessment of lesion resectability, implantation of pacemaker lead wires, and correction of vascular anomalies.3 Currently, endoscopy is most widely applied for diagnostic procedures in veterinary medicine, and the limitations are being reached. The future of endoscopy in veterinary medicine centers around therapeutic and interventional procedures. Therapeutic endoscopy is only limited by the innovation and skill of endoscopists.

Equipment The type of flexible fiberoptic or video endoscope purchased (see Common Equipment Manufacturers) depends on personal preference. Because the image is displayed on a screen, video endoscopes are advantageous for sterile applications during surgery and as a teaching tool, with examinations recorded onto a standard videotape for further review. However,

Common Endoscopy Manufacturersa Karl Storz Veterinary Endoscopy 175 Cremona Drive Goleta, CA 93117 800-968-7776 www.karlstorz.com Pentax Precision Instrumentation Corp. 30 Ramland Road Orangeburg, NY 10962-2699 800-431-5880 www.pentaxmedical.com Olympus America Inc. 2 Corporate Center Drive Melville, NY 11747-3157 516-844-5000 www.olympus.com aIn

addition to these major manufacturers of endoscopic equipment, numerous dealers also sell the equipment.

video capability is not required for the procedure. In addition, if a flexible fiberoptic endoscope is initially purchased, a video camera can be purchased later. Flexible endoscopes are available in various diameters and lengths (Figure 1). The flexibility of endoscopes varies between two- and four-way directional bending. Four-way bending allows greater manipulation of the endoscope tip, thus providing endoscopists with a better view of the area being examined; however, this feature costs more. The size of the biopsy port should also be considered, especially if multiple endoscopes are being purchased, because one set of instruments can be used in multiple flexible endoscopes if the diameter of the biopsy port is the same on all of them. Rigid endoscopes (Figure 2) are available in various diameters, ranging from 1.9 to 10 mm. Larger-diameter rigid endoscopes provide more light for better visualization and photo-

Compendium April 2000

Figure 1—Flexible endoscope with 7.9-mm outer diameter, 2-mm channel, 100˚ field of view, 210˚ up angulation, 90˚ down angulation, and 100˚ right and left angulation.

graphic results and thus serve as a better teaching tool. Smaller-sized endoscopes facilitate applications in small patients but have less field of view and transmit less light. Although traditional thoracoscopic instrumentation is shorter than that commonly used in laparoscopy, laparoscopic instruments can easily be substituted in veterinary patients, which markedly decreases the cost of obtaining specific thoracic instrumentation in practices that already perform laparoscopy. In addition, for such procedures as rhinoscopy, cystoscopy, and arthroscopy, rigid endoscopes can be used instead

Common Endoscopic Accessories Aspiration tubes Biopsy forceps and needles Bougies for stricture dilation Cryosurgery probes Curettes Cytology brushes Dissectors Electrocoagulation forceps and snares Exploration probes Forceps and baskets for removing foreign bodies Forceps for removing sutures Gastrointestinal staplers Hemostatic clip applicators Needle holders Power-driven cartilage shavers Rongeurs Scissors Special suture material Tissue graspers

Small Animal/Exotics

Figure 2—Arthroscope with 2.8-mm diameter and 30˚ angle.

of small flexible endoscopes, which are more expensive. Accessory equipment (e.g., sleeves, bridges) is needed to use rigid endoscopes for diagnostic and therapeutic procedures (e.g., guided biopsies, foreign body retrieval). The gastroscope (Figure 1) and 2.8mm diameter 30˚ arthroscope (Figure 2) are the workhorse endoscopes in veterinary practices. The gastroscope can be used for all GI procedures and bronchoscopy in medium- and largebreed dogs. The arthroscope can be used for rhinoscopy, sinoscopy, and bronchoscopy in small dogs and cats, laparoscopy, cystoscopy, vaginoscopy, prepuceoscopy, otoscopy, and arthroscopy. Additional endoscopes depend on the demands of each practice but might include a 4-mm diameter rigid cystoscope and 5-mm diameter flexible endoscope.

The light source for endoscopy is remote from the area of examination to allow a much brighter light to be used and avoid the problems of inadequate lighting and heat damage to tissue. The term cold light source evolved because light is transmitted by the fiberoptic bundle but heat is not. Although a 150-watt tungsten light source is less expensive, it may not be adequate in some situations. Greater illumination can be produced by a 300-watt xenon source, but many of today’s more sensitive cameras do not require excess lighting. In addition to the endoscope and light source, accessory instrumentation (see Common Endoscopic Accessories) is needed to collect samples, perform certain surgical procedures, and remove foreign bodies. Although accessories are relatively expensive, they are not cost prohibitive. Maintenance costs are minimal if accessories are cared for properly (Table One).

Space Considerations The amount of space devoted to endoscopy depends on the goals of the practice. Flexible endoscopes and accessory instruments should be stored hanging vertically, with care to protect

TABLE ONE Endoscopic Equipmenta Equipment Flexible fiberoptic endoscope Endocoupler Video endoscope light source Rigid endoscope Light cable Tungsten light source Xenon light source Monitor, printer, and video recorder Insufflator Flexible endoscopic accessories Rigid endoscopic accessories

Estimated Cost (New) $8000–$16,000+ $700–$900 $6500 $1800–$3000 $200 $400–$750 $3500 $700–$3500 $4000–$5000 $200–$500+ $200–$500+

aAnnual maintenance costs approximately $1000 to $2000 per endoscope, and the average lifetime of endoscopes is about 10+ years with good maintenance.

Small Animal/Exotics

the camera at the distal end. Thus a storage closet should be included in the purchasing plans. Except for rigid endoscopes, endoscope cases should only be used for transporting the endoscope and not for routine storage. Rigid endoscopes can be stored in their case or a padded drawer. A standard cart can be lined with foam for storing most rigid endoscopic equipment, with the light source and video equipment on top. No additional surgical space is needed to perform endoscopic procedures.

Cleaning and Sterilization In general, manufacturers will instruct veterinarians and their staff on appropriate cleaning and care of endoscopic equipment. After each procedure has been completed, endoscopes and accessories should be cleaned according to the manufacturer’s instructions. Most rigid endoscopes can be routinely sterilized for such procedures as arthroscopy, cystoscopy, laparoscopy, and thoracoscopy. Flexible endoscopes used for sterile procedures need to be chemically or gas sterilized according to the manufacturer’s instructions.

Compendium April 2000

Training and Education Endoscopy must be learned hands-on. Many universities and national meetings now offer courses in endoscopy, complete with wet labs to familiarize veterinarians with techniques and applications of a variety of equipment. For the novice endoscopist, learning proper technique for endoscopic procedures will initially be slow and cumbersome. Handson completion of multiple procedures is usually needed before manipulation of the endoscope becomes familiar and the endoscopist becomes more adept and efficient. References 1. Bailey JE, Freeman LJ, Hardie RJ: Endosurgery, in Bojrab MJ, Ellison GW, Slocum B (eds): Current Techniques in Small Animal Surgery, ed 4. Baltimore, Williams & Wilkins, 1998, pp 729–746. 2. Kelling G: Ueber oesophagoskopie, gastroskopie und kölioskopie. Munch Med Wochenschr 49:21–24, 1902. 3. Walton RS: Diagnostic video-assisted thoracoscopy. Sixth Annu ACVS Symp Small Anim Proc:393–396, 1996. 4. Cushieri A, Dubois F, Mouiel J: The European experience with laparoscopic cholecystectomy. Am J Surg 161:385–387, 1991.