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Imaging Equipment and Operating Room Setup
Fausto Brandão and Christopher Chamness
Imaging Equipment
While human medicine has defined the major trends and achievements in minimally invasive surgery (MIS) over the past 2 decades, veterinary medicine has followed in its path and developed specialized techniques and instrumentation. The high costs and enormously diverse options of equipment sets available may seem discouraging to many veterinary practices. The goal of this chapter is to help practitioners to make rational choices for a fully equipped MIS operating room (OR). Careful selection of the most versatile, durable, and modular devices is often the best choice for veterinary practitioners.
Imaging Chain
The most basic video endoscopy imaging system consists of a light source, light-transmitting cable, endoscope, camera, and monitor (Figure 3.1). Each component is essential, and the resulting endoscopic image can only be as good as the weakest link in the chain. For example, if a surgeon has a very high-quality camera, telescope, and light cable but chooses to use a low-resolution consumer-grade television as a monitor, the resulting image quality will be limited by the monitor. Even an old, damaged, or dirty light cable can degrade the image quality of an otherwise high-end endoscopic imaging system.1-4 An image troubleshooting guide is presented in Table 3.1.
Table 3.1 Image Troubleshooting Guide
| Problem | Possible Cause | Resolution |
| Image is not clear | Fogged or dirty lens | Blot distal lens of telescope on live tissue or apply antifog agent to lens. |
| Fogged distal lens | Immerse telescope in warm sterile water or apply antifog agent to lens. | |
| Dirty eyepiece, camera, or adapter | Clean using cotton swab moistened with sterile water. | |
| Lens not adjusted to operator’s eyesight | Rotate focus adjustment ring on camera head until image is clear. | |
| Internal fluid damage or cracked rod lens | Moisture within telescope will permanently cloud lens in distal end or eyepiece (repair by manufacturer). | |
| Misconnected camera on telescope eyepiece | Check for proper coupling and positioning of camera head to telescope by adjusting adapter. | |
| Image is too dark or too bright | Dirty light guide | Clean light-guide connector and distal tip using gauze moistened with sterile water. |
| Improper light source or camera settings | Adjust brightness control knob, camera gain, or manual aperture setting. | |
| Old or improperly installed lamp | Properly install lamp; replace old lamp. | |
| Image is too blue | White balance improperly done or not done before telescope insertion into patient | Remove telescope from patient, clean distal lens, and perform white balance correctly. |
| Deficient illumination | Bulb lifespan ending | Check working hours on light source; replace bulb or activate alternate bulb inside light source. |
| Improperly connected light cable | Check for correct and full insertion of light-transmitting cable. | |
| Worn light cable (broken fibers) | If >30% of light-transmitting capacity is lost, then substitute cable. | |
| Light source on stand-by mode | Check and press stand-by button to activate light output. | |
| Light source is turned down | Increase light source output. | |
| Loss of pneumoperitoneum | Empty tank or closed valve from gas supply | Check gas remaining in tank; replace tank; open valves of general gas supply. |
| Open Luer-lock on one or more trocars, leaking gas | Check and close all stopcocks except the one coming from insufflator. | |
| Blockage of line going to patient | Be sure tip of Veress needle is not blocked by tissue and that the valve on the Veress needle or gas input cannula is open to incoming gas. | |
| Leaky cannula valve or sealing cap | Assure proper assembly and functioning of each cannula and replace any worn sealing caps. | |
| Leakage around portal sites | Check for leakage around wounds and suture closed where necessary. | |
| No image on screen or monitor or black and white image only | Connector into front of the camera control unit (CCU) is not fully inserted, dirty, or wet | Clean and dry the connector and replace securely. |
| Video cables between the CCU and monitor are faulty or not tightly connected | Tighten connections and replace cables, if necessary. | |
| Camera head cable that connects to CCU is damaged | Send to manufacturer for repair. | |
| One or more devices in the video chain are not activated or damaged | Check that all devices in the video chain are turned on and have proper and tightly connected power cords. |
Figure 3.1 The basic endoscopic imaging chain. (© 2014 Photo Courtesy of KARL STORZ GmbH & Co. KG.)
The light generated by the light source is transmitted by the fiberoptic light cable, and farther down the telescope, by fiberoptics to illuminate the anatomy being observed. The image is transmitted through a series of lenses from the distal end of the telescope to the eyepiece, where the chip in the video camera head senses the image and transmits it to the camera control unit (CCU), which processes the endoscopic image and transmits it to a monitor for viewing. This video projection enables the surgeon to maintain an ergonomic posture and to share the visual information with observers. Furthermore, video imaging facilitates documentation of procedures, in several formats, valuable for client education, medical records, teaching, or consultation purposes.1-4 Video imaging also enables remote access to a live procedure via streaming video.5
Telescopes
Rigid endoscopes are more convenient than flexible endoscopes for examining and performing procedures in body cavities.6-8 Rigid scopes (i.e., telescopes) are also much simpler in design and less expensive than flexible endoscopes. Despite containing lenses and fiber optics, they do not contain flexible materials, are easier to clean and maintain, and have a longer working lifespan.9 Some models may include a working channel, integrated instrument, or a variable viewing angle, which allows a wider viewing field. State-of-the-art rigid telescopes are constructed with high-quality optical glass rod lenses (Hopkins rod lenses), producing high-quality images that are bright, magnified, wide angle, and of high resolution and contrast.1-4,8 No single model of rigid endoscope is universally suitable. The appropriate sized telescope should be selected based on the surgical procedure, size and morphology of the patient and ultimately by the preference and experience of the surgeon. Although smaller scopes tend to be more versatile, they are also more prone to breakage, and their illumination capacity is limited when used in larger, more light-absorptive cavities such as the abdomen or thorax of large breed dogs.
Standard surgical telescopes come in a variety of sizes (Figure 3.2). The most versatile and popular rigid telescopes used in small animal laparoscopy and thoracoscopy are 5 mm in diameter and approximately 30 cm in length. Smaller rigid endoscopes, 2.7 or 3 mm in diameter and 14 to 18 cm long are ideal for cats, puppies and toy breeds. With a smaller diameter and shorter shaft, these are easier to maneuver in smaller patients but too short in larger patients, and light-carrying capacity may be inadequate in larger cavities. Telescopes larger than 5 mm in diameter have decreased in popularity, mostly because of the improvements in image size and brightness of 5-mm telescopes.1-4,7,8
Figure 3.2 Rigid endoscopes. From top to bottom: 10-mm ENDOCAMELEON, 10 mm, 5 mm, and 4 mm. (© 2014 Photo Courtesy of KARL STORZ GmbH & Co. KG.)
Conversely, the 10-mm-diameter operating laparoscope has become popular. It contains optics similar to that of a 5-mm telescope but has an integrated working channel that allows passage of 5-mm instruments down the same shaft. Operating scopes are available in two types, right angled or oblique (Figure 3.3). Some surgeons prefer this style of telescope for certain routine procedures such as biopsies and ovariectomies because the instruments are always under visual control. For this reason, an operating telescope may also be recommended for novice endoscopic surgeons.1-4
Figure 3.3 Operating laparoscopes. A. Right angled. B. Oblique. (© 2014 Photo Courtesy of KARL STORZ GmbH & Co. KG.)
The viewing angle of a telescope is an important consideration because it affects both orientation and visual access (Figure 3.4). Standard forward-viewing telescopes (0 degree) provide the simplest spatial orientation, centered on the axis of the telescope, but they present a relatively limited viewing field. A 30-degree viewing angle allows the surgeon to view a larger area by simply rotating the shaft of the telescope on its longitudinal axis.7,8 With experience, the operator becomes proficient at using angled telescopes and gaining a wider viewing field. Telescopes with more acute tip angulations are also available (70, 90, and 120 degrees), but they are rarely used in small animal laparoscopy and thoracoscopy.1-4
Figure 3.4 Telescope viewing angles. A. Zero degree. B. 30 degree. (© 2014 Photo Courtesy of KARL STORZ GmbH & Co. KG.)
New 10-mm-diameter rigid telescopes are available with a variable viewing angle, allowing the surgeon to control angulation from 0 to 120 degrees, with a mechanical twisting mechanism near the eyepiece (ENDOCAMELEON; Karl Storz GmbH & Co., Goleta, CA; Figure 3.5). These newer telescopes are only beginning to gain popularity among veterinary surgeons, mainly because of cost and large diameters.
Figure 3.5 Telescope with variable viewing angle, adjusted by turning the collar on the eyepiece. (© 2014 Photo Courtesy of KARL STORZ GmbH & Co. KG.)
Using a telescope and instruments of the same diameter (i.e., 5 mm) is convenient for maximum flexibility during surgery and allows exchanging location of the telescope and instruments during a procedure without exchanging ports.1-4,8 Nevertheless, trocar cannulae can be fitted with a reducer (Figure 3.6) to accommodate smaller diameter instrumentation without loss of pneumoperitoneum.8
Figure 3.6 A 10-mm trocar and cannula fitted with a 10/5 reducer that can be flipped into place for 5-mm instruments. (© 2014 Photo Courtesy of KARL STORZ GmbH & Co. KG.)
Light Sources
The power (expressed in watts) and type of a light source are two of the main factors determining the brightness, clarity, and color accuracy of an endoscopic image. Condition and quality of light-transmitting cables, cleanliness of lens surfaces, light sensitivity of the camera, and monitor type also contribute to image brightness and quality.1-4,7,10-13
The most common types of high-quality light sources today are Xenon, Hi-Lux, and LED, typically ranging in power from 50 to 300 W. The wattage of a light source is not necessarily indicative of its brightness but indicates the energy required to power it, which does not directly correlate to brightness (expressed in lumens). Therefore, wattage alone is not valid for comparison of light sources of different types. As a general rule Xenon, Hi Lux, and LED light sources produce brighter, whiter light (∼6000–6500° Kelvin) than older halogen light sources (3400° Kelvin). For example, a 50-W Hi-Lux light source emits an amount of light similar to a 125- to 175-W Xenon light source.1-4
Currently, the Xenon light source is the most popular because it offers excellent tissue color reproduction with light closely approximating that of pure sunlight (5800° Kelvin). However, LED technology is increasingly used because of greater efficiency, long lifetime, small size, and light weight. An LED bulb will last approximately 30,000 hours, 30 times that of a xenon light bulb. Spare bulbs should always be available, or a light source equipped with two bulbs should be considered.1-4,10,12
When selecting a light source for multidisciplinary endoscopy services, including flexible endoscopy, the compatibility with a modular pump for insufflation and irrigation, and attachment of endoscope to the light source are important (Figure 3.7). Although the initial cost of a versatile, high-power light source may be high, it could represent considerable savings later, if it prevents the purchase of multiple light sources. When not in use, the light source should always be in stand-by mode or completely turned off, to avoid any thermal injuries to the patient or surgical drapes.1-4,6,7
Figure 3.7 Light sources. A. LED light source with connector for standard light cable. B. Xenon light source with connector for gastroscope. (© 2014 Photo Courtesy of KARL STORZ GmbH & Co. KG.)
Light Cables
A fiberoptic light guide cable transmits the light from the light source to the telescope. The light cable consists of a bundle of thousands of optical glass fibers ranging in size from 30 μm to several hundred microns, surrounded by a protective jacket, and equipped with metal fittings at each end. Cables with additional armoring last longer than ones without this protection. The cable is inserted into the light source at one end and attached to the light post of the telescope at the other end. Light cables are available in various styles and diameters, depending on the diameter of the telescope. Correct matching prevents overheating or underillumination. Generally, a smaller scope requires a smaller light cable. The most common cable used with 5-mm telescopes for small animal MIS is 3.5 mm in diameter and 230 cm long (Table 3.2).1-4
Table 3.2 Matching Diameter of Telescope and Light Cable for Optimal Illumination and to Avoid Overheating
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