LAT Chapter 13 Surgical Instruments & Materials PDF

LAT Chapter 13 Surgical Instruments & Materials Quality surgical instruments are expensive, and they will deteriorate rapidly if mishandled. Laboratory animal technicians should be familiar with commonly used instruments and how they are cleaned and sterilized. This chapter is intended to introduce...

LAT Chapter 13 Surgical Instruments & Materials Quality surgical instruments are expensive, and they will deteriorate rapidly if mishandled. Laboratory animal technicians should be familiar with commonly used instruments and how they are cleaned and sterilized. This chapter is intended to introduce you to these instruments Surgery on laboratory animals is a common procedure in biomedical research. Any laboratory animal technician involved in surgery must have specialized knowledge about the instruments used in surgery and how to properly maintain and sterilize them. Forceps -Thumb Forceps • Thumb forceps are tweezer-like instruments that have two jaws and spring handles. They are held like a pencil; the sides have wide serrations (grooves) for grasping securely. The jaws close with pressure applied by the fingers and thumb, and spring open when released. • Thumb forceps are used for compressing, securing, or grasping tissue or dressings. • Dressing and tissue thumb forceps are distinguished by the inner surface of the blade tip; there are various sizes of each type. • Dressing forceps: have a smoothly serrated tip, with low ridges. These forceps may be used to handle vessels and other tissues lightly; however, grasping tightly can cause a crush injury in the tissue. • Tissue forceps: have articulated teeth at the blade tip to grasp tissues more securely. • Adson or Ewald patterns: Small-toothed forceps that are acceptable for holding soft tissues. • Thumb forceps with large teeth should be used sparingly on tissues, as the teeth can inflict injury. The origin of the word comes from Latin, “forca,” which means to grab or grip an object Hemostatic Forceps • Hemostatic forceps, also known as hemostats, are designed to clamp onto bleeding tissue containing a severed vessel. • The jaws may be straight or curved. • The hinge is called a box lock (Figure 13.2). • The operator’s fingers are inserted into the ring handles. • A ratchet sets the blades at three different clamp pressures; hence, hemostats are often called clamps. Any tissue clamped by hemostat jaws is crushed, so hemostats should not be used to grasp tissues. This crushing force is, however, an advantage to stop bleeding in vessels. When used for hemostasis, only the jaw tips should be clamped onto the tissue containing the vessel stump. • Common patterns include the Halstead mosquito hemostat, used on small vessels, and the Kelly hemostat, used on larger vessels. • Rochester-Carmalt forceps have crushing jaws with longitudinal grooves and cross grooves at the tip. These forceps are often used to clamp across a tissue mass that contains a blood vessel. Other Forceps • Allis tissue forceps have serrated jaws, and the teeth curve toward the inside of the blades. These forceps exert minimal damage to tissues while providing a strong grip, often allowing a structure to be fixed in position for an operation. • Towel forceps are used to fix a sterile drape to the skin at the surgical site. The sharp tapered tips pierce the skin, securing the drape without applying any crushing force. • The Backhaus towel forceps is a common pattern. Other pattern feature a stainless-steel ball near the tip to prevent the drape from sliding down the instrument jaws. Needle Holders • Needle holders secure the needles used to suture (stitch) tissues closed and are used for knot tying. • These instruments have a box lock hinge, ring handles, and a ratchet. • High-quality needle holders have a durable jaw insert of tungsten carbide, which may be replaced by the manufacturer when worn out. • The jaw tips are blunt and have a cross pattern to hold a suture needle. A common pattern is Mayo-Hegar. • Some patterns have a longitudinal groove cut into the jaws’ inner surface to further aid in grasping a suture needle. • The Olsen-Hegar pattern has scissor blades below the jaws for cutting suture strands after a suture is tied. • Needle holders are available in various sizes; the correct size should be used for the size of the needle to avoid damaging the jaws and ratchet. A needle that is too large for the needle holder may cause the ratchet to become sprung, so the ratchet will no longer hold its setting but will spring open unexpectedly during use. Needles • Needles are sharp instruments used for suturing. A surgical needle is described by its shaft shape (curvature) and point type of the tip. Needles may be straight or curved. • Curved needles are classified by what portion of a circle their length represents. The most common sizes are 1/2 circle or 3/8 circle. • The common needle tip types are tapered, conventional cutting, reverse cutting, and taper cutting. • Tapered needles have a smooth shaft that ends in a sharp point at the tip; these needles are used for penetrating soft tissues offering no resistance to the needle. • Conventional cutting and reverse cutting types, the needle has a triangular shape from the tip to one third of its curvature; each edge of the triangle is a sharp blade. • The difference between these two types is the orientation of the triangle’s apex, which is on the inner curvature of the conventional cutting needle and on the outer curvature of the reverse cutting needle. • Conventional cutting needles are typically used for skin sutures, as they can pierce the tough hypodermis. • Reverse-cutting needles are typically used for ophthalmic or cosmetic surgery as they cause less trauma and can decrease the occurrence of sutures pulling through the tissue. • A tapered cutting needle combines reverse cutting edges at the tip of a tapered needle. Surgeons may prefer a particular type of cutting needle for some procedures. The shaft of the needle (also called the body) varies in shape according to the tip design. For example, the cross section of tapered needles is round near the tip but ovoid in the body, making it easier to grasp with a needle holder. • Some needles have an eye to thread the suture material. However, most have suture material already attached securely to the needle end. The attached suture is called swaged-on, and that end of the needle is called the swage. Swaged-on suture is used commonly in surgery both for the convenience of the surgeon and for lack of trauma when the needle and suture are pulled through the tissues. Suture Materials • The material used for wound closure must be strong yet pliable, easily sterilized, and cause minimal reactions in the body. • Most suture materials are available in presterilized packs, and may be swaged on needles of various sizes, types, and curvatures. • The surgeon selects the suture type and size to be used. Suture material can be classified by the following characteristics: • Material: Suture material can be made from natural materials, like silk or collagen, or from synthetics, like hexafluoropropylene, nylon, polyester, poliglecaprone, polydioxanone, polyglactin, and polypropylene.  Catgut is a collagen material derived from cattle or sheep intestines. Catgut comes in two forms, plain and chromic. Absorption of plain catgut in tissues can cause severe and painful inflammation that undermines wound healing. In the chromic form, the catgut is treated with chromic salts, which slows the rate for the sutures’ absorption, thereby reducing the inflammatory reaction in the tissues.  Stainless steel, in the form of wound clips, is also considered a suture material. • Absorbability: Absorbable sutures are broken down and assimilated by the body over time. Synthetic absorbable suture materials are often preferred, as they cause little inflammatory reaction. Nonabsorbable suture materials, like nylon, remain in the body permanently when placed in tissues below the skin, and may need to be removed. • Filament type: Suture material can be monofilament or multifilament. Monofilament is a single untwisted fiber. Multifilament, also known as braided, consists of multiple fibers twisted together into a thread. Monofilament suture pulls smoothly through tissues but tying a secure knot can be difficult due to fiber stiffness. Multifilament sutures are more pliable, so knot-tying is easier; however, these sutures are more likely to wick microorganisms along the braided fibers, which can cause wound infections. Suture Materials • The material used for wound closure must be strong yet pliable, easily sterilized, and cause minimal reactions in the body. • Most suture materials are available in pre-sterilized packs, and may be swaged on needles of various sizes, types, and curvatures (Figure 13.7). • The surgeon selects the suture type and size to be used. Suture material can be classified by the following characteristics: • • Material: Suture material can be made from natural materials, like silk or collagen, or from synthetics, like hexafluoropropylene, nylon, polyester, poliglecaprone, polydioxanone, polyglactin, and polypropylene. Catgut is a collagen material derived from cattle or sheep intestines. Catgut comes in two forms, plain and chromic. Absorption of plain catgut in tissues can cause severe and painful inflammation that undermines wound healing. In the chromic form, the catgut is treated with chromic salts, which slows the rate for the sutures’ absorption, thereby reducing the inflammatory reaction in the tissues. Stainless steel, in the form of wound clips, is also considered a suture material. • • Absorbability: Absorbable sutures are broken down and assimilated by the body over time. Synthetic absorbable suture materials are often preferred, as they cause little inflammatory reaction. Nonabsorbable suture materials, like nylon, remain in the body permanently when placed in tissues below the skin, and may need to be removed. • • Filament type: Suture material can be monofilament or multifilament. Monofilament is a single untwisted fiber. Multifilament, also known as braided, consists of multiple fibers twisted together into a thread. Monofilament suture pulls smoothly through tissues but tying a secure knot can be difficult due to fiber stiffness. Multifilament sutures are more pliable, so knot-tying is easier; however, these sutures are more likely to wick microorganisms along the braided fibers, which can cause wound infections. • Suture materials are sized by their diameter using a numbering system established by the United States Pharmacopeia. Numbers 1 to 6 denote progressively thicker sutures. At the opposite end of the scale, below 1, successively finer sutures are sized by an increasing number of zeros. The number of zeros is indicated by a digit, followed by a dash and a zero. Here, a zero is called aught. For example, a 3-0 suture (pronounced “three aught”) represents three zeroes (000). This size is a moderately fine suture diameter often used in suturing subcutaneous tissues in large animals. The finer 5-0 suture (“five aught”, representing 00000) is more likely to be used in a rodent (Figure 13.8). Finer material is used for more delicate tissues, as it places less stress on the closed wound. Larger suture material is made for larger wounds and larger animals. Suture materials range in size from 12-0 (the smallest) to 10 (the largest). Suture materials differ in the sizes in which they are available. Suture sizes and characteristics are set by the US Pharmacopoeia, an organization that establishes reference standards for the pharmaceutical field. Staples • In place of sutures, a skin incision can be closed using wound clips. Wound clips are placed with an applicator that works much like a staple gun. • After the skin heals, the clips must be removed with a clip remover. • The wound clips and these instruments are sterilized by autoclaving. Surgical adhesive • Another option for skin wound closure is a surgical adhesive, which is administered from an applicator bottle. • Such adhesives are based on cyanoacrylate, the same material in Super GlueTM. Surgical adhesives based on other polymers may be used for internal wound closures and in reconstructive surgeries. • These adhesives are slowly degraded by mechanical and biological processes and are slowly removed from the site by the body. Scalpel Handle & Blades • A scalpel is a rigid cutting instrument for incising or puncturing tissue. • The Bard-Parker scalpel handle (Figure 13.10) has a rib (known as a rib-back) onto which a disposable scalpel blade is locked in place. The scalpel handle is sized by number; 3 and 4 are the most common sizes. The handle has smooth serrations to ensure a firm grip by the surgeon. • Scalpel blades are available in various sizes and shapes (Figure 13.11). • • • • Number 10 blade: Commonly used; it fits on a number 3 handle. This blade has a broad, round cutting edge used for larger, less delicate tissues. Number 11 blade has a straight edge and a sharp point. Fits on a number 3 handle. Number 15 blade has a small cutting edge; it is used for fine, delicate surgery, such as rodent surgery. Fits on a number 3 handle. Number 20 blade: has a broad, round cutting edge, is larger than the Number 10; Fits on a number 4 scalpel handle. • Loading and removing a scalpel blade can cause injuries unless safe handling practices are used. Never handle a blade with your fingers. • To load: Use a Kelly hemostat to grasp the blade and insert its opening onto the rib-back of the scalpel handle. Slide the blade towards the handle until you hear a click, which means the blade is locked on. • To remove: Clamp a hemostat onto the blade at its base. Lift the blade slightly, then slide it towards the handle tip and lift it off the rib-back. Various safety devices can be used to remove and cover a scalpel blade to prevent injury during removal and disposal. Alternately, disposable scalpels are available, as are retracting and shielded scalpels, where a device is deployed to cover the blade after use. Scissors • Scissors are classified by the shape of the blade tips. Blade types include: • Blunt-blunt, meaning that both tips are blunt; • Blunt-sharp, meaning that one tip is blunt, and one is sharp • Sharp-sharp, meaning that both tips are sharp. • Blunt-blunt scissors are preferred for dissection of living tissue because they minimize tissue damage. Scissor blades can be straight or curved, and the blade edges may be smooth or serrated. Serrated scissors are used for cutting thick bandages or cartilage. Scissors are designed for specific purposes: • • • • • • • operating dissecting tissues cutting sutures cutting wire sutures removing sutures cutting bandage material • To protect and preserve scissor blades from damage, only use scissors for their designated purpose. Retractors • Retractors increase the exposure of a surgical site. They may be used to apply a stretching or pulling force, such as at the wound margins to widen the view within the incision. Retractors may also hold back organs to expose deeper structures. • Retractor blades are wide and curved or angled; the shape of the blade minimizes tissue trauma. • Hand-held retractors have either a textured handle for a secure grip or a double-ended lip, so one lip can press against a wound margin while the other lip serves as a brace for the surgeon’s hand. • Many self-retaining retractors have ring handles and a ratchet, like the Weitlaner retractor. In this type, the blades spread apart when the ratcheted handles are closed. Dental Instruments • Dental procedures require specialized instruments for treating diseased and fractured teeth and for performing tooth extractions. • A dental scaler removes calculus (calcified debris) from teeth. • A dental elevator is used to perform a dental extraction. It’s used to separate the gum from the tooth and then break down the periodontal ligaments holding the tooth in its bony socket of the jaw. • This instrument has a small narrow blade at the tip. • A series of larger blade sizes may be used to progressively loosen the tooth in its socket until freed. • Extraction forceps has jaws shaped like a tooth. Is used one the tooth has been loosened enough to be grasped and removed. Cleaning Surgical Instruments Since saline or blood can splash on the instrument tray during surgical procedures, all instruments must be cleaned whether they were used or not. Instrument Maintenance - Cleaning • When surgery has been completed, separate all needles, scalpel blades, and other disposable sharp objects from the other instruments and discard them in a puncture-proof sharps container. Separating sharps from the other instruments helps protect personnel cleaning the instrument pack from injury or exposure to animal tissues. • Next, separate delicate instruments so they will not be damaged by other instruments during clean-up. • Instruments should be cleaned immediately after use to remove microorganisms, blood, and tissue debris. Immediate cleaning prevents these materials from drying and adhering to the instruments, which helps keep them in good working condition. • If there are unavoidable delays in cleaning, the entire pack of instruments should be rinsed in water and placed in a plastic bag to prevent residues from drying. • Since saline or blood can splash on the instrument tray during surgical procedures, all instruments must be cleaned whether they were used or not. • Give every instrument individual attention during the cleaning process. • Open the instruments to expose all areas for cleaning. Blood and tissues encrusted in the crevices of an instrument can cause corrosion, which could result in rusting and cracking when the instrument is stressed. • Use a soft brush and a pH-neutral detergent to clean instrument serrations, ratchets, box locks, hinges, and screw joints. • Instruments with removable parts must be disassembled for cleaning. • Hard water can produce staining, which may be prevented with a final rinse of deionized water. • After manual cleaning, instruments may be cleaned ultrasonically. An ultrasonic unit converts high-frequency sound waves into mechanical vibrations within a specially formulated detergent solution to remove residual debris from instruments. These vibrations help the detergent solution reach areas that are inaccessible to a brush. • Once cleaned, inspect instrument jaws and moving parts for any residual blood or tissue debris. Instrument Maintenance – Quality Control • When instruments are cleaned, check instrument function: Instrument jaws and teeth should fit together perfectly, not overlap. Box locks should be free of cracks. Hinges should open and close smoothly, not stiffly. Ratchets should close freely and hold position at each ratchet tooth. Close a hemostat or needle holder to the first tooth, or “click.” Then tap the ring handles gently on a hard surface. The ratchet should not spring open; if it does, it might open unexpectedly during surgery. • An instrument with warped or broken jaws, stiff hinges, or sprung ratchets cannot be used in surgery; it must be repaired or replaced. • Some instruments can be sent to the manufacturer for repair. Instrument Maintenance - Lubrication • Prior to repacking the surgical kit, lubricate hinges and other moving parts. • Lubrication temporarily smooths the action of instruments with moving parts and helps extend their useful life. • Surgical instrument lubricants are commercial preparations that do not interfere with sterilization by autoclave or gas sterilants. • They are based on water-soluble mineral oil, so they are penetrable by steam. • As instrument lubricant is removed by washing, so it should be reapplied after each cleaning. steps for cleaning instruments 1. Rinse instruments in water as soon as surgery is completed. 2. Open all locks and disassemble instruments if possible. 3. Thoroughly scrub each instrument with a soft brush and instrument detergent under warm water. 4. An ultrasonic cleaner may be used to clean inaccessible areas and tightly bound debris. 5. Rinse instruments with hot water to ensure complete removal of detergent. 6. If rinse water is hard, rinse again in deionized water to remove minerals. 7. Dry instruments thoroughly. 8. Inspect instruments for cleanliness and proper function. 9. Apply a surgical instrument lubricant to hinges and other moving parts. 10. Repack for sterilization. Sterilizing Surgical Instruments & Materials Surgical materials can be sterilized by autoclave, ethylene oxide gas, hydrogen peroxide plasma, dry heat, or liquid sterilants. Sterilization Methods for Wrapped Instrument Packs • Autoclave sterilization is the most common method of sterilizing wrapped packs that contain instruments, gowns, drapes, and other heat tolerant items for use during a surgical procedure. • Gas sterilization with ethylene oxide gas or hydrogen peroxide plasma vapor is an effective method of sterilizing most surgical items— particularly items that are sensitive to high heat or humidity, such as some plastic materials and electronics.  The use of ethylene oxide requires a special chamber with a vent to the outside of the building, as it is toxic.  All items sterilized in this manner must be allowed to air out for a minimum of 12 hours following the sterilization procedure in order to prevent accidental exposure to the gas.  Personnel performing ethylene oxide sterilization must wear a monitoring badge to detect any exposure. • Sterilization with hydrogen peroxide plasma vapor does not have these safety requirements, because water and oxygen are the only by-products in this method. • Items are packed in see-through pouches or wrapped in drape material that is permeable to the steam or gas sterilant. • Indicator tape may be placed on pack exteriors, and indicator strips may be included in pack interiors. At the end of the cycle, a color change in these indicators proves sterilization temperatures have been reached. Effective sterilization methods • Effective sterilization of surgical materials depends on properly functioning equipment and sufficient temperature, pressure, and exposure time (see Chapter 5). The following are generally accepted guidelines for sterilization of surgical equipment and supplies for any kind of sterilizer.  Clean all instruments and materials prior to sterilization since dirt, blood, and other gross contaminants greatly reduce the effectiveness of sterilization.  Launder all gowns, drapes, and other washable fabrics before sterilizing. The use of disposable gowns and drapes eliminates the need for laundering.  Arrange packs so that steam or gas can circulate between packs. Inside a pack, spacing of instruments and materials should allow steam or gas circulation. Sterilization failures may result from packs that are wrapped too tightly or are improperly loaded in the sterilizer.  Pack and wrap materials in a way that allows opening of the pack without contaminating the contents.  Use a sterilization indicator to show that proper sterilization has occurred. Indicators are placed in the center of the pack in addition to sealing packs with color indicator tape. If the center of the pack has reached sterilization conditions, a color change occurs on the indicator.  Label packs on the outside with the date sterilized. Packs remain sterile for up to 6 months if they are correctly wrapped, stored properly, and remain dry and sealed. Wetness destroys the effectiveness of the wrapper as a contamination barrier because it wicks in microorganisms to the pack interior. Additional Sterilization Methods In some cases, sterilization methods may not be possible or appropriate for packaged materials. For example, in situations where the same surgery is performed on multiple individuals in succession, it may not be practical to use packaged sterile instruments. In these cases, alternate methods may be used. Glass bead sterilizer • A glass bead sterilizer is a small unit for quickly resterilizing metal surgical instruments. These devices utilize dry heat sterilization by heating glass beads in a small cup to temperatures of 250 °C to 265 °C. • Cleaned instrument tips are pushed into the beads and are sterilized in about 10 seconds (Figure 13.19). • Only the tips of the surgical instruments are sterilized; therefore, no other part should come into contact with the surgical field. • Due to the extremely high heating temperature in this device, it is imperative that instruments remain in the sterilizer no more than 1 minute and are allowed to cool prior to contacting living tissue. • In preparing to do multiple rodent surgeries:  Initially autoclave the instruments.  After each surgery, clean blood and tissue debris from the instruments with moistened gauze.  Resterilize instrument tips and cool while the animal that has undergone surgery is placed in a recovery cage and the next animal is prepared for surgery. Gauze pads, aka ‘sponges’ are used during surgeries to soak up blood and other fluids from the surgical site. Liquid chemical sterilization, aka “cold” sterilization • Liquid chemical sterilization, sometimes called “cold” sterilization, is usually reserved for surgical instruments and medical devices that are heat-sensitive but can be immersed in liquid, such as endoscopic equipment. • Common liquid sterilizing agents include peracetic acid, hydrogen peroxide, glutaraldehyde, and orthopthaldehyde. • The latter two, which are classed as aldehydes, are very irritating to tissues and are associated with respiratory illnesses in workers exposed to them. • Instruments must be rinsed thoroughly with sterile saline before allowing them to come in contact with the animal. Summary There are many more surgical instruments, some quite specialized, than the few introduced here. However, as you continue to learn more about these instruments, you will find that the fundamentals of instrument type and care that were presented in this chapter will apply to other instruments you will encounter. If performing rodent surgeries becomes one of your duties, a task not uncommon for technicians, you will need to become proficient in using surgical instruments for tissue handling and wound closure.