What to Look For When Choosing a Flexible Endoscope

British Small Animal Veterinary Congress

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Philip Lhermette, BSc(Hons), CBiol, MIBiol, BVetMed, MRCVS

Elands Veterinary Clinic

Dunton Green, Sevenoaks, Kent

 

Flexible endoscopy has been used in human and veterinary medicine for many years. Over time instrumentation has become more sophisticated and prices have reduced, encouraging more widespread use. With a vast array of new and secondhand endoscopes on the market, it is easy to make a wrong decision and be left with an expensive white elephant. No single endoscope will be suitable for all procedures in small animal practice. It is therefore important to understand your clinical requirements first of all and then to understand enough about endoscope design and function to find an instrument to meet them.

Types of Flexible Endoscope

There are two main types of flexible endoscope in common clinical use. Gastroscopes and bronchoscopes. Gastroscopes should have four-way tip deflection (at least 180 degrees in one direction), automatic air/water insufflation, a biopsy/suction channel and a working length of at least 100 cm. For large breeds a working length of 130-150 cm is essential to examine the small intestine and caecum. The diameter of the insertion tube should be no larger than 10 mm or it will not be possible to pass through the pylorus of smaller patients. A diameter of less than 8 mm makes passage through the pylorus easier in small dogs and cats but must be offset against the smaller biopsy channel--usually around 2 mm as against 2.8 mm in the larger endoscope. Smaller biopsy samples can be more difficult for pathologists to interpret.

Bronchoscopes should have two-way tip deflection of at least 100 degrees in each direction, and preferably 180 degrees in one direction to allow retroflexion over the soft palate. You will also require suction and air/water insufflation, a biopsy/working channel and a working length of at least 80 cm. An outer diameter of 2.8-5 mm is ideal for all adult dogs and cats, although a 7-8 mm gastroscope can double as a bronchoscope for medium to large dogs.

Flexible endoscopes can be further divided into fiberscope and videoendoscopes. Fibreoptic endoscopes transmit the image to the eyepiece via a bundle of coherent fibres, resulting in a pixelated image that is viewed directly through the eyepiece or via an attached camera, on a monitor. A videoendoscope has no eyepiece, the image being transmitted electronically from a CCD or CMOS video chip at the tip of the insertion tube directly to a video monitor. This gives a vastly superior image but at greater cost, since each endoscope essentially incorporates its own camera system.

Decide What Sort of Endoscope You Need

An endoscope must be fit for purpose--what is your caseload? Do you deal primarily with cats, small dogs, or large dogs? Do you see mainly gastrointestinal (GI) or respiratory cases? What quality, especially of optics, do you require? Do you feel that a warranty is important and what about servicing costs and loan of an instrument during repairs? Look at the individual characteristics of an instrument--does it feel good in your hands; is it comfortable to use?

One endoscope is rarely sufficient and you will eventually purchase another, or you may already have a range of rigid endoscopes. How can the new endoscope be integrated with current equipment and future expansion plans? Can you use the same light source and camera system on all your endoscopes to spread the cost? What is the total cost--both initial and ongoing maintenance? How are you going to recoup this?

New or Secondhand

An important decision to make is whether to buy new or secondhand. There are a lot of excellent 'veterinary specific' endoscopes appearing on the market. These are more suited to our patients than many human models, having a 130-150 cm insertion tube as standard. In addition, buying new provides you with a warranty for at least a year, and servicing and spares should not be a problem. Suppliers will usually be happy to provide training in use, care and maintenance free of charge for yourself and your staff. Proper care is vital if your investment is not to be damaged, incurring expensive repairs

Large numbers of secondhand endoscopes are available from the human market. However--'caveat emptor'--there are a number of things to look out for:

 Insertion tube length. Most human paediatric endoscopes are 100 cm, too short for GI work in large dogs.

 Insertion tube diameter >10 mm is not suitable for small animal work.

 Size of instrument channel--aim for 2.8 mm with a minimum of 2 mm. Pass an instrument through the channel to ensure there is no blockage or damage to the channel.

 Check the rubber at flexible tip for perishing or damage.

 Some older hospital endoscopes hitting the market are not fully immersible, making cleaning and adequate disinfection extremely difficult.

 Fibre damage. Remember there are light guide fibres in a video endoscope as well. Look for adequate light transmission by viewing the image with the endoscope tip placed in a large dark box. (Your hand will reflect too much light and show a good image in any case.) Check fibreoptic endoscopes for black spots on the image in the eyepiece and on a monitor, depicting broken fibres.

 Damage to guide wires. These are the wires that move the flexible tip of the endoscope. The tip should move through the whole range of movement expected--and at least 180 degrees in one direction. The tip should start moving as soon as the wheel or lever is moved, with no delay. On gastroscopes, the tip should be straight with the control wheels in the neutral position (usually with the U & L markers uppermost).

 Is the instrument water tight? This is vital as the delicate fibres and guide wires are very easily damaged by the slightest leak, and repair can cost almost as much as a new endoscope. Always attach a leak tester to the pressure compensation port and inflate to the prescribed pressure. Look for a pressure drop. If you are unsure, immerse the pressurised endoscope in water and look for escaping bubbles.

 Accessories, spares and servicing. Does the endoscope come with necessary accessories such as a leak tester, pressure compensation valve, cleaning brushes and all the necessary buttons and grommets for the working channel? Is there any documentation giving the cleaning instructions? Where will you get it serviced and are spare parts still available?

Where to Buy

New

Major manufacturers in both the human and veterinary market produce their own endoscopes. These are usually the most expensive, but are high quality instruments backed up by a large company that is unlikely to disappear, good supplies of spare parts and excellent service contracts that will often loan a replacement instrument if yours is not functional. Many veterinary resellers also offer excellent deals on instruments manufactured by smaller companies. Often the quality is not quite so high, but this is reflected in the price, and you will still get a warranty and excellent service deals.

Secondhand

Secondhand equipment can be bought direct from hospitals, via hospital auctions or even on eBay. However, purchasing flexible endoscopes this way is fraught with danger and you can easily end up with an expensive piece of junk that costs more to repair than it is worth. A number of resellers offer secondhand reconditioned equipment that will at least have been tested and will come with a short warranty. Try and persuade them to allow you to use it on trial for a month or so on real cases before purchase.

Care and Maintenance

With proper care and maintenance your endoscope should last years:

 Always clean your endoscope thoroughly immediately after use with an enzymatic cleaner. Dried debris can block channels and be extremely difficult to remove.

 Resterilise your endoscope after cleaning using gas sterilisation or a recommended cold steriliser.

 Always use a manufacturer-recommended enzymatic cleaner and cold steriliser. Inappropriate chemicals can damage seals.

 Storage. Always store your endoscope hanging with the insertion tube vertical and the buttons removed to allow the channels to drain. Fibres retain a memory if coiled and will be more prone to breakage if constantly coiled and straightened. Never store your endoscope in its case. This not only coils the insertion tube, it provides an ideal environment for bacterial growth within the endoscope. Pseudomonas is commonly isolated from incorrectly stored endoscopes.

References

1.  Chamness C. Instrumentation. In: Lhermette, P; Sobel, D. eds. BSAVA manual of endoscopy in the dog and cat. In production expected late /.

2.  Chamness C. Introduction to veterinary endoscopy and endoscopic instrumentation. In: McCarthy, T. ed. Veterinary endoscopy for the small animal practitioner. Elsevier Saunders, ; 1-20.

3.  Chamness C. Endoscopic instrumentation. In: Tams, T. ed. Small animal endoscopy, second edition. St Louis: Mosby, ; 1-16.

A medical endoscope is a device used for performing endoscopy. Endoscopy is a non-surgical procedure that helps to view and examine the digestive tract. The medical endoscope consists of several components that provide pictures of the digestive tract. It includes:

• A flexible or rigid tube
• A light delivery system that illuminates the specific organ or object which requires inspection. Most commonly the light source is placed outside the body and light is targeted at the site via an optical fiber system.
• A lens system which transmits the image to the viewer. Typically, in case of a fiberscope it uses a bundle of fiberoptics, and in rigid endoscopes it uses a relay lens system.
• An eyepiece: Advanced instruments use videoscopes without any eyepiece. A camera transmits image displaying it on the screen that is used for image capture.
• An additional channel to facilitate entry of medical instruments

In some situations, patients may undergo sedation which has its own challenges and risks.

What are techniques of using medical endoscope?

Medical endoscopy is widely used and is a minimally invasive technique indicated for diagnostic purpose and surgical techniques.

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• Insertion of the endoscope takes place via the mouth if examination of stomach and bronchial tubes is required.
• Through the nostrils in case of assessment of nostrils, sinuses or vocal cords.
• Through the colon if examining colon

Certain situations may require additional intervention to examine the target area thoroughly. For example, sometimes a small incision may be needed to insert the endoscope such as in abdominal region (laparoscopy).

What are the different types of medical endoscopes?

There are three kinds of medical endoscopes:

Rigid optical endoscope

It consist of a rigid rod with lenses. At one end of the endoscope there is lens, while on the other end a socket for connecting the eyepiece and the light source. It also provides additional area to attach a video camera head onto it. Rigid endoscopes usually have metal tubes, consisting of the lenses, and light channels. They are available in a wide range of external diameters ranging from 1-12mm.

The fiberscope

It is also called as flexible optical endoscope. The mechanism of action for rigid and flexible optical endoscope is similar, and the only difference is of stem which is flexible in fiberscope due to presence of an optical fiber. Thus, it is easier to access sinuous areas, especially few parts of the larynx. On the other hand, the stem should be used gently as the stem is thin, flexible and fragile.

Video-endoscope

This type of endoscope has flexible rod and a CCD sensor at its end which provides video images. It can also have one or more working channels in its stem usually for the placement of endoscopic instruments. This is useful in polypectomy, prostate enucleation etc. The video-endoscope should be handled delicately due to the fragility of the sensor located at the end. Few video laryngoscopes can be rigid. They consist of a blade and can be integrated with a video monitor to allow quick viewing, particularly in case of emergency intubation.

What are the main applications and advantages of medical endoscopes?

Rigid endoscopes

• These are the oldest types of endoscopes. Rigid endoscopes are used in majority of surgical endoscopic applications enabling visualization of organs, vessels and any pathologic changes in the structures.
• Most of the endoscopes do not require any additional incisions and provide a clear view of the internal components.
• Depending on few parameters and design criteria the image results can vary. This includes viewing angle, image brightness, image size, depth-of-field and distortion. Hence, all these features should be appropriately balanced. Common indications for rigid endoscopes include rhinoscopy (nose), laparoscopy (abdomen) and cystoscopy (urinary bladder).

Virtual endoscopy such as virtual colonoscopy and virtual bronchoscopy helps the clinicians to examine internal structures in a non-invasive manner by using advanced imaging techniques.

Robotic flexible GI endoscopy

In recent times, robotic platforms in endoscopy are becoming popular to allow best possible outcome and minimal risks related to use of endoscopes. Current endoscopic devices have their own diagnostic and therapeutic limitations which will be overcome with the help of robotic assisted surgery. Robotic platforms will improve the safety and precision of the traditional tools making them more efficient and reliable.

Robotic platforms have several benefits:

• In COVID-19 situation, use of robotic device will allow to maintain a safe distance between the patient and operator by using remotely controlled devices. This will result in less risk of infection as there will be no droplet contact and aerosol contamination 
• Robotic devices are simple and easy to operate. 
• Reduce the training times
• Useful in cases where fine motor skills are required which are beyond the scope of human dexterity.
• Improves precision and control over the device, hence less risk and complications observed with the robotic platforms.
• They will lower patient discomfort by reducing the torque and force applied at the target area.
• Better image will be obtained due to precise control and management of the device compared to the conventional techniques.

What are the recent trends?

Endoscopic ultrasonography

• Endoscopic ultrasonography (EUS) has an ultrasound transducer of high-frequency which is attached at the tip of the endoscope. This provides high-resolution images of the gastro-intestinal wall and adjoining structures. 
• EUS-guided fine needle aspiration (EUS-FNA) is a recent technique that uses a thin needle allowing aspiration of the tissue under the ultrasonographic guidance.
• There are few other therapeutic procedures that can be performed under the guidance of real-time ultrasound, such as EUS-guided celiac plexus blockage and EUS-guided drainage.

Wireless capsule endoscope

It is basically a diagnostic tool. The system has a disposable video-recorder capsule and a 7-hour battery which transmits the recorded images to a data recorder. This data recorder is attached to patient&#;s waist. There is a computer workstation with software facilitating reviews and interpretation of results.

WCE can be conducted in an outpatient setting. The capsule is ingested after a 10-12 hour fasting period without sedating the patient. It moves through the small intestine through peristalsis.

Percutaneous endoscopic gastrostomy

• Percutaneous endoscopic gastrostomy (PEG) is a type of endoscopic procedure that allows placement of tube through the abdominal wall. Different indications for PEG include cancer of the oropharynx, impaired swallowing conditions (stroke), and tumor of the larynx and esophagus.
• It is also beneficial for patients with malignant bowel obstruction. This endoscopic technique should be avoided if peroral feeding is expected to resume in a month. Application and case selection of PEG is debatable.

In this method when the radiation targets the tissue at a specific wavelength, unique molecules known as fluorophores will release the absorbed energy in the specific radiation form. Based on the spectrum analysis and assessment of the emitted radiation, the nature of the tissue can be characterized. The final fluorescent image when overlapped with the traditional image will help in the diagnosis.

What things should be considered while using medical endoscope?

Medical endoscopy is a safe procedure, and the risk associated with the use of endoscopes is generally low. In some rare situations few complications can be seen such as:

• Infection at the site where endoscope was used for examining the particular area. This may require treatment with antibiotics.
• Piecing or tearing of a tissue or organ.
• Bleeding which may need surgery to repair the damaged tissue.

In some cases, sedation may be needed which can sometimes cause adverse events such as:

• Breathing problems
• Low blood pressure (hypotension)
• Burning sensation at the injected site
• Feeling sick

Conclusion

Endoscopes are an integral component in the medical field. They allow a clear image of the internal structures such as organs, tissues and vessels etc. With recent advances in technology, several new developments have led to the introduction of fiberscope, video-endoscope, ultrasound and robotic assisted surgical intervention. Different kinds of endoscopes are used for a wide range of applications in order to allow successful outcome in diagnostic and therapeutic purposes. A detailed and thorough examination of the target site is possible with endoscopes, which should be selected based on individualized needs and requirements.

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