Veterinary Endoscopy for the Small Animal Practitioner. Группа авторов

Figure 2.17 An open‐surgery handpiece for use with the ForceTriad that seals and cuts in one instrument.

      (Source: Photo courtesy of Covidien Division of Medtronic's.)

      2.2.7 Irrigation Fluid Management Systems

      Continuous or intermittent irrigation is used for many diagnostic and operative endoscopy procedures. Intermittent irrigation with suction is used for laparoscopy and thoracoscopy. Continuous irrigation is used for cystoscopy, rhinoscopy, vaginoscopy, prepuceoscopy, transabdominal nephroscopy and ureteroscopy (TANU), transabdominal cholecystoscopy choledocoscopy and enteroscopy (TACCE), fistuloscopy, laceroscopy, oncoscopy, oculoscopy, analsacoscopy, and otoscopy. There are three different techniques used to maintain fluid flow: gravity flow using liter containers of fluid placed above the patient with an IV set connected to the fluid port on the telescope cannula; pressure‐assisted flow with a manual pressure cuff added to the gravity flow system; and automatic or manually controlled mechanical infusion pumps. Fluid inflow through the telescope cannula functions to distend structures for examination and to create a clear view by washing blood and debris away from the lens of the telescope out of the visual field. For most procedures, fluid outflow is simply through the naturally occurring space around the telescope sheath. For cystoscopy, outflow is either through the telescope sheath by intermittently stopping inflow and allowing outflow or with a double coaxial sheath allowing continuous simultaneous inflow and outflow. Laparoscopy and thoracoscopy use carbon dioxide for insufflation of distension to create a visual space with irrigation used for lavage and suction used to remove the fluid, blood, and any contaminants. Suction may also be used during otoscopy. Transabdominal procedures use suction to remove fluid from the abdomen but not from the abdominal organ being examined.

      Lactated Ringer's solution, Ringer's solution, and physiologic saline solution are the most commonly used fluids. One‐, three‐, and five‐liter bags of sterile IV solutions are available for irrigation. The larger sized bags have the advantage of requiring less‐frequent container changes during procedures than smaller bags. Their disadvantages are that they are more cumbersome to handle than one‐liter bags and one‐liter containers are less expensive per liter than their larger counterparts.

      2.2.7.1 Gravity Flow

This is the simplest, easiest, and least cumbersome technique for maintaining irrigation and works well for most diagnostic and many of the basic operative procedures. The technique uses IV fluid bags connected to an intravenous fluid administration set that is then connected to the inflow port in the endoscope sheath. Air is bled from the IV line prior to use to minimize air bubbles that will interfere with the visual field. Intravenous administration sets are available with a filter in the cap on the patient end of the line (Figure 2.18) that allows air to escape but prevents liquid leakage. The fluid bag is hung at an appropriate level above the patient and the intravenous administration set flow controls are opened fully. The stopcock on the telescope sheath is then used to start and stop fluid flow. Fluid pressure and organ distension are controlled by the level the bag is placed above the patient. The rate of fluid flow is controlled by inflow pressure and by egress resistance. A high‐flow low‐pressure system is effective in maintaining a clear visual field.

Figure 2.18 An intravenous fluid administration set with a filter in the cap on its end that allows air to escape but retains fluid. This type of cap facilitates bleeding air out of the line.

      (Source: Hespira LifeShield Primary IV Set 12661‐28 and Hespira LifeShield Extension Set 12658‐28.)

      2.2.7.2 Pressure‐Assisted Flow

      Gravity flow is adequate in most cases for diagnostic and operative procedures and pressure‐assisted flow is rarely needed. A manually inflatable pressure cuff is placed around the fluid bag to increase pressure when needed. This system is inexpensive and is easy to set up and use. Disadvantages are that pressure needs to be repeatedly added to the bag during the procedure, changing bags can be cumbersome, and the potential for excessive pressure exists. Using two fluid bags with two pressure cuffs facilitates changing bags because when one bag is empty, the fluid line is quickly and easily changed to the second bag. The pressure cuff from the empty bag is then transferred to a new full bag so that it is ready for the next exchange. There are many manufacturers and sources of these pressure cuffs.

      2.2.7.3 Mechanical Fluid Pumps

Mechanical pumps are available that provide manually controlled increased inflow pressure and suction to facilitate fluid management. One of the fluids pumps is designed for cleaning ears when managing otitis externa (Figure 2.19). With proper pressure adjustment and by allowing ready outflow of fluid around the telescope sheath, exudate, wax, and debris are easily removed from the ear canal with limited or minimal risk of rupturing the tympanum. Surfactant or detergent can be added to the irrigant to speedup cleaning. This pump also works well for irrigation and suction with minimally invasive surgery. The bottles and tubing are autoclavable, so the system is usable in an aseptic setting.

Figure 2.19 A Vet Pump 2 fluid management system with irrigation and suction pumps. Pulsating adjustable high‐pressure irrigation is produced by this unit that functions well for ear cleaning and for debriding lacerations, fistulas, and for lavage of contaminated abdomens and thoraxes. A two‐button control module at the patient end of the tubing allows one‐handed management of irrigation and suction.

      (Source: Photo courtesy of Karl Storz: ©Karl Storz SE & Co KG, Germany.)

      2.2.8 Operating Tables

      Standard veterinary operating tables are usable for many endoscopic procedures but specialized tables allowing patients to be tilted from end to end in both directions and from side to side in both directions are a great asset. Cystoscopy, rhinoscopy, otoscopy, laceroscopy, fistuloscopy, oncoscopy, oculoscopy, and analsacoscopy are performed on a flat horizontally positioned table. Laparoscopy and thoracoscopy require tilting tables. Some simple abdominal and thoracic procedures are performed on a flat table by repositioning the patient under the drapes, but this is cumbersome and is inadequate in many situations. Using a standard surgical table that is manually tilted end to end in one direction will work but planning ahead is critical to make sure that the tilt of the table is aligned with the direction needed for the planned procedure. If the patient is positioned in the wrong direction, it is extremely difficult to be corrected after draping. Securing the patient to the table is also very important so that the patient does not slide off the table when it is tilted. Some newer surgery tables are tiltable end to end in both directions. A table of this kind is desirable for minimally