7. R.S.P.- Lesson 3 Review

Anesthesia machines also have

- Control meters that allow you to regulate how much oxygen and anesthetic are delivered to the patient - A scavenging unit (such as a canister containing activated charcoal) that removes waste anesthetic gases - A canister filled with soda lime, which binds up exhaled carbon dioxide so that the patient doesn't rebreathe its exhaled gasses . The soda lime, which turns purple after it reacts with carbon dioxide, must be changed when the purple level reaches one third the depth of the material.

Endotracheal intubation pt2

- Step 5: Gauze is tied around the tube so the tube can be attached to the head. - Step 6: The gauze is then tied around the patient's head to maintain the endotracheal tube in position. - Step 7: The veterinarian or veterinary technician will use a 5- to 10-ml syringe to inflate the cuff of the trachea. This cuff prevents the anesthetic gas from escaping around the tube and out through the animal's mouth and prevents aspiration (breathing in) should the animal vomit. - Step 8: The endotracheal tube is then attached to the anesthesia machine so that oxygen and a gas anesthetic agent can be administered directly into the animal's respiratory tract. . Endotracheal tubes come in a variety of diameters and lengths to fit animals of many different sizes (from small birds to large zoo animals).

Laparotomy

. A laparotomy is a surgical incision into the abdomen. Strictly speaking, a laparotomy refers to an incision in the flank (side of the abdomen) of an animal, but the term is commonly used to refer to any incision into the abdomen . It can be done in any species of animal for a large number of surgical diseases involving the abdominal contents . An exploratory laparotomy, a common term in veterinary surgery, involves cutting into the abdomen to look for a disease process (such as tumors or intestinal foreign bodies) and then surgically correcting the problem.

Necropsy

. A necropsy is a scientific, systematic dissection of a dead animal . The veterinarian performs this procedure to identify any pathology (disease of body organs or tissues) that might be present in a dead animal . It's usually performed to help determine the cause of the animal's death . It might be performed if a patient dies unexpectedly or to identify the extent of a disease process that affected the animal . For instance, if an animal had a tumor in its spleen, a necropsy might be done to determine if the tumor spread and to identify the organs affected by the spread of the cancer. . A complete necropsy examines every organ in the animal, including abdominal and chest cavity organs . The veterinary assistant's role during a necropsy is to assist the veterinarian in properly caring for and preparing tissue samples for analysis and to make certain that the appropriate forms are properly filled out and submitted.

Disposal of Deceased Animals

. A number of companies provide services for the disposal of animal bodies . All veterinary hospitals have a large freezer that's used to temporarily store dead bodies . When an animal dies, it's usually placed in a sturdy plastic bag and then in the freezer . The disposal company usually sends a truck to the hospital at specific intervals (typically once a week) to collect the bodies. . What's done with the bodies varies . Usually, they're cremated and the ashes are taken to a sanitary landfill . The body can also be individually cremated and the ashes can be returned to the owner for burial . Some companies also offer burial of the animal's body in a pet cemetery . Finally, some owners pick up the body of their pet for burial at home . In this instance, the body must be prepared for transport home, usually by placing it in a sturdy bag and then within a box (cardboard or plastic coffins can be purchased).

Operative Record Keeping

. A number of things must be tracked and recorded during surgery . Most of the time, this is the job of the anesthetist . After the animal is prepped for surgery, but before the first incision is made, a count of all surgical sponges should be made . The sponges are then counted at the end of surgery, before the incision is closed . This is done to make sure that no sponges were left inside of the animal(It can happen.) . Likewise, all surgical instruments should be accounted for at the end of surgery.

Operation and Maintenance of Suction and Cautery Machines

. A suction unit enables a surgeon to suction, or remove, fluids from a surgical site . This device is particularly useful when it's necessary to lavage (rinse) an abdominal or chest cavity . During lavage, sterile saline is poured into the cavity . A sterile suction catheter is attached to a sterile length of tubing, which is attached to the suction unit . The suction unit creates negative pressure, which is transmitted up the tubing to the catheter . The catheter is then inserted into the fluid within the cavity and suctions the fluid from the cavity . The fluid flows through the tubing and into a collection container in the suction machine.

Prolapsed Organs

. A variety of organs can prolapse in many species, including large, small, and exotic animals . Most organs that prolapse are hollow tubular organs, such as the rectum and the uterus . A prolapsed organ is one that passes from its normal location out through an orifice (hole) . For instance, a prolapsed rectum passes from its normal position in the pelvic canal out through the anus . The prolapsed organ thus sits on the outside of the animal and is exposed to the outside environment, where it could easily be traumatized. . Prolapsed rectums are seen most commonly in puppies, kittens, and pigs . Usually resulting from straining to defecate, they're typically seen in unthrifty animals (often due to internal parasites) and animals with diseases of the large intestines . Uteruses can also prolapse, most commonly when the animal is giving birth, as seen in cows and sometimes in small animals . Most of the time, the prolapsed organ can be pushed back into its normal position, but sometimes surgery is needed to return it to its normal location.

Personnel

. After surgery, all surgical gloves and gowns are removed and disposed of. (If the gown is made of reusable cloth, it should be cleaned and autoclaved.) . If the scrub suit has blood or debris, it should be changed before the next surgery . If needed, hands and arms should be washed with an antiseptic soap.

Assisting the Surgeon

. After the animal is placed on the operating table and the surgery site is prepared, the surgeon needs assistance preparing for his or herrole in the surgery . The instrument pack must be opened using aseptic technique . Surgical drapes, scalpel blades, suture material, and other instruments that might be needed for the surgery are also opened on the surgery tray using aseptic technique . Gowns and gloves are also opened to allow the surgeon to "gown up" and "glove in."

Preparing the Surgical Site Using Aseptic Technique pt3

. After the hair is clipped, the initial surgical scrub should be done in the surgery preparation room . A variety of surgical scrub soaps are available, but the two most commonly used soaps are chlorhexidine and povidone-iodine . Each of these has a rapid onset and is effective against a broad spectrum of bacteria (up to a 99% bacterial kill rate within 30 seconds after application) . The initial skin prep involves removing clipped hair and gross contamination (collected dirt or oils) from the clipped area . Gauze sponges soaked with the scrub soap are used to gently scrub the surgery site . It's important to begin scrubbing in the center of the clipped area (the site where the incision will be) and then scrub toward the outside of the clipped area . After the scrub sponge has passed over the outer part of the clipped area, never return it to the center (to avoid contamination)

Surgical Equipment and Supplies

. All equipment used in surgery—including instruments, drapes, gowns, tables, lights, and anesthesia machines and anesthetic monitoring equipment—must be clean and in good working condition . Surgical instruments should be checked before use to make certain that they can do their job . For instance, a hemostat must be able to effectively clamp a bleeding vessel . They should be cleaned after use and packed for sterilization so that they're ready for the next surgery . Surgical tables and lights should also be kept very clean and checked to make sure they're working properly . The anesthesia machine and anesthesia monitoring equipment should be well maintained to work properly . It's also important that quantities of all supplies used in surgery (intravenous catheters, gowns, gloves, drapes, special equipment, etc.) are checked to ensure that there's enough in stock to perform the surgery . Running out of instruments or supplies endangers the patient and frustrates the surgeon.

Cleanup Equipment, Surgical Room, and Instruments

. All instruments used during surgery must be cleaned and sterilized . All blood and organic debris must be removed from the instruments, usually using a soft brush and water . The instruments are allowed to dry and then are reassembled into an appropriate surgical pack . The pack is then placed in an autoclave (a machine used for sterilization) and sterilized for the next surgery . The surgery table and other structures in the surgery room (lights, floor, etc.) must be cleaned with an antiseptic solution, such as chlorhexidine . The anesthesia machine is checked to make sure it has enough gas anesthetic for the next procedure . The endotracheal tube is also cleaned with an antiseptic . The cuff of the endotracheal tube is inflated to check for leaks . (This check should also be performed just before it's used for anesthesia.) . All pieces of equipment, such as the ECG machine and the blood pressure monitor, are cleaned if needed and checked to make sure that they're in working condition for the next procedure.

Intravenous Fluids pt2

. Although the kidneys are vital to the health of every animal, the body will shunt (divert) blood away from the kidneys, if needed, to maintain blood flow to the brain and heart . If blood is shunted away from the kidneys for too long, the kidneys could go into failure . Intravenous fluids such as lactated Ringer's solution, Normosol R, or normal saline are given through the intravenous catheter at a rate necessary to help maintain blood pressure . Recommended fluid rates for anesthetized patients of most species are 5-10 mL/kg/hr

Anesthesia Machine

. An anesthesia machine is a nearly indispensable part of performing anesthesia . Anesthesia machines are designed to deliver a specific amount of a gas anesthetic agent at a specific rate . The machine also helps to deliver oxygen to the patient. . The veterinarian and veterinary technician will be responsible for maintaining and utilizing the machines . However, it will be helpful for you to understand the mechanics of them.

endotracheal tube

. An endotracheal tube is long rubber tube that's inserted through the animal's mouth into its trachea (a tube-like structure that allows air to flow to the lungs) . The equipment needed for endotracheal intubation includes - Various sizes of endotracheal tubes - Stylets in assorted sizes - Sterile syringe - Laryngoscope - Sterile lubricant - Gauze

Onychectomy

. An onychectomy (declawing) is the surgical removal of the claws and associated third phalanx (segment of the digit closest to the claw) . A common procedure in cats, it's done primarily to prevent a cat from destroying furniture as it scratches . Most often, only the claws of the front legs are removed, but some owners also want the back claws removed. . In dogs, onychectomies are done to remove thedewclaw (the nail of the first digit, on the inside of the foot) . This procedure is usually done when the animal is a few days old, but it can be done in older puppies or dogs . The main reason for this surgery is to prevent a dog from losing its dewclaw by getting it caught on an object while running.

Ovariohysterectomy

. An ovariohysterectomy, or spay, is the surgical removal of the ovaries and the uterus . The most common surgical procedure performed in female dogs and cats, it's done in almost every female puppy and kitten from six to nine months old . Breeding animals may have it done when they're older . Ovariohysterectomies are most commonly performed through a ventral midline incision . (The animal is on its back and the incision is made in the center of the abdomen, usually between the umbilicus and the pubis.) . The vessels leading to the ovaries are ligated (tied off) with suture, the body of the uterus is ligated, and the ovaries, uterus, and uterine horns are removed . Because this surgery is very common, most veterinarians are experienced with it, and it usually proceeds very quickly . This is major abdominal surgery, and placement of an intravenous (IV) catheter and full anesthesia monitoring is recommended . In animal shelters and high volume spay/neuter clinics, these animals may not receive IV catheters since the surgeries are performed so rapidly. . Ovariohysterectomies are rarely performed in large animals . Occasionally, an oophorectomy (surgical removal of the ovaries) is performed in cows and horses—usually in the standing animal through an incision in the vagina.

The basic components of an anesthesia machine are

. An oxygen source - A vaporizer, which evaporates, holds, and helps deliver the gas anesthetic - Tubing, through which the oxygen and anesthetic are delivered - A bag, which can be used to assist in breathing . Even if the animal is breathing on its own while under anesthesia, it isn't doing so efficiently, since it can't fully expand its lungs . The bag allows us to "breathe for" the animal and to periodically fully expand the lungs to allow more efficient gas exchange.

Asepsis and Operating Room Conduct

. Apart from maintaining the health of the patient, following aseptic technique is the most important aspect of surgery . Aseptic technique refers to all of the procedures that are followed to prevent infection from developing in the patient . This technique includes proper preparation of the surgery site (clipping hair and scrubbing), proper instrument sterilization, and proper conduct in the surgery room . Unless scrubbed, gowned, and gloved, you shouldn't touch or go near the surgery table, the surgical instruments, or the surgery site on the patient . Everyone who goes into the surgery room during a procedure should be wearing clean surgery scrubs, a cap, and a mask . Always be aware of where everything is in the surgery room and what you can and can't touch.

Preanesthetic Preparation

. Before a patient is anesthetized, all of the equipment and supplies to be used should be checked to make sure they're present and in good working condition. . Maintaining the anesthetic equipment may be the responsibility of the veterinary assistant . It will be necessary for you to become familiar with the operation of the anesthetic system used in your hospital . The oxygen source, anesthetic machine, and breathing circuit must be checked for leaks . To prepare the anesthetic machine, use the following procedure. . Step 1: Fill the vaporizer with the appropriate anesthetic liquid. . Step 2: Check the oxygen equipment and connect to the oxygen supply. . Step 3: Evaluate the soda lime absorbent. Replace if the material is exhausted or purple in color. . Step 4: Turn on the flowmeter.

Patient

. Before recovery, blood spilled during surgery should be cleaned from the patient . The best way to clean off blood is to use a soft cloth or surgical sponge and cold water or hydrogen peroxide . Hydrogen peroxide works very well at breaking down dried blood . Since hydrogen peroxide can be very damaging to normal tissue, it's important not to get it into the surgical wound or on the incision line . If animal feces or urine is present on the patient's skin or hair, you should remove as much of it as you can before the animal recovers— usually with a damp towel.

Caesarian Section

. Caesarian sections are performed in pregnant animals having difficulty giving birth to their offspring . Dystocia is the term that describes the difficulty in giving birth . Caesarian sections are most commonly performed in dogs, cats, and cows . This surgery involves cutting into the pregnant uterus through an incision in the abdomen to retrieve the fetus(es). . There are a number of reasons why a Caesarian section might be necessary . It's frequently performed when the fetus is too large to travel normally through the birth canal or when the fetus is in an abnormal position that prevents it from passing . There are also some medical conditions that prevent normal birth. . In dogs and cats, a Caesarian section may be done alone or may be combined with a spay to prevent the animal from getting pregnant again (and possibly having difficulty delivering again) . This surgery is usually performed via a ventral midline incision in dogs and cats . In cows, it's usually performed through a flank incision (the cow is standing, and the approach is through the side of the abdomen).

Castration

. Castrations are often performed to prevent unwanted breeding . Castration, the surgical removal of the testicles, is the most commonly performed surgery in male dogs and cats and is frequently done in large animals (particularly horses, sheep, and pigs) . Usually done at an early age (around six months), castrations are strongly recommended in dogs, cats, and horses that won't be used for breeding . Two tools commonly used for castration are an emasculator and an emasculatome. . The emasculator is used on horses to crush and cut the cord during an open castration . The emasculatome is used on cattle and sheep to crush the spermatic cord without breaking the skin . Castrations also can help prevent a large number of diseases (such as prostatic diseases), particularly in dogs . The testicles are removed either by making an incision in the scrotum over each testicle (scrotal approach) or by cutting the skin in front of the scrotum (prescrotal approach).

Materials and Equipment Needed for Preanesthetic Preparation

. Clippers . Syringes (marked) with induction drug(s) . Intravenous catheter(s) . Appropriate-size endotracheal tubes . Catheter cap . Syringe to inflate endotracheal tube cuff . White tape . Laryngoscope . Intravenous fluid bag . Gauze to tie in endotracheal tube . Intravenous administration set . Eye lubricant . Pole or other device on which to hang IV fluid bag . Syringes with flush solution . Functioning ECG and blood pressure monitors

Dehorning

. Dehorning is usually done in young cattle and goats (ideally at about one to two weeks of age) . Horns in mature cattle and goats can be potentially dangerous to people and to other animals . The horns in young animals can be removed by either using a Barnes scoop dehorner, which cuts off the horn and the tissue that makes the horn grow, or by using a heated metal element that burns off the horn bud . If this procedure is done early enough (by two weeks of age), no anesthetic agent is needed . Older animals are anesthetized, and the horn is cut off with a saw.

Disposal of Hazardous Medical Waste

. Different states have different rules about the disposal of surgical waste . Most states require that sharp items, such as used scalpel blades and needles, be placed in special "sharps containers." . These containers are made of heavy plastic with a lid that can be permanently sealed . When the container is full, the lid is sealed and the container is delivered to a service licensed to dispose of hazardous waste materials . These materials are usually either burned or buried . Unneeded specimens, such as a removed organ (a spleen, for instance, or a uterus from a spay) may need to be placed in special bags for disposal.

Operative Record Keeping pt2

. During administration of anesthesia, the anesthetist should keep a record of all of the parameters monitored during surgery . Respiratory rate, heart rate, temperature, end-tidal CO2, oxygen saturation, and blood pressure are usually checked many times during surgery (ideally, every five minutes) . All of these vital parameters must be followed closely.

Endotracheal intubation

. Endotracheal intubation allows the anesthetist to directly see the opening of the larynx so that he or she can place the endotracheal tube into the trachea . The following procedure is used to pass an endotracheal tube. - Step 1: Using a gauze sponge or paper towel, grasp the patient's tongue with your right hand if you're standing on the right side of the animal. - Step 2: Open the animal's mouth to facilitate passing the endotracheal tube. - Step 3: The veterinarian or veterinary technician will place the laryngoscope over the animal's tongue. - Step 4: The endotracheal tube is inserted into the patient's trachea.

Operation and Maintenance of Fiber Optic Equipment pt2

. Fiberoptic endoscopes are long, tube-shaped, flexible instruments that are composed of many fiberoptic filaments, a light, channels that allow suction and aspiration, and a viewing area . Most endoscopes have a mechanism that allows the tip to be moved from side to side and up and down . A camera can be attached to the viewing port so that people can monitor what's seen through the endoscope on a TV monitor.

Operation and Maintenance of Fiber Optic Equipment pt3

. Fiberoptic endoscopes have very delicate components and must be handled with care . They shouldn't be dropped or bent sharply . These scopes must be cleaned between uses, usually with water or an antiseptic solution, to prevent contamination from one patient to the next . They should be stored in a safe place (such as a closet or a wood or metal box specifically designed to hold endoscopes), where they can't be damaged . In most hospitals, one person is specifically trained to handle and clean endoscopes so that there's less risk of an unqualified person accidentally damaging them.

Operation and Maintenance of Fiber Optic Equipment

. Fiberoptic equipment allows the direct visualization of objects that normally can't be directly seen . For instance, a fiberoptic endoscope allows a doctor to see the inside of a patient's stomach . Endoscopes can be used to diagnose many diseases and treat many problems . For instance, it can be used to visualize and retrieve some foreign bodies from the esophagus and stomach . It can be used to look into the trachea and lungs to help diagnose problems such as a collapsing trachea, pneumonia, and cancer and to obtain samples for pathological assessment . It also can be used to look directly at the larynx in horses to identify problems that might affect the horse's ability to breathe properly.

Gas anesthetics

. Gas anesthetics, like isoflurane, desflurane, and sevoflurane, are used in veterinary medicine to maintain anesthesia . An anesthetic machine containing one of these agents is connected to the endotracheal tube, and the gas is administered at a level sufficient to maintain the patient at a general anesthetic plane . The anesthetic is placed into the vaporizer, where it will volatilize (evaporate, or be changed into a gaseous state). . The gas form of the anesthetic is carried along with the oxygen to the patient through the anesthesia machine tubing and the endotracheal tube . The anesthetic machine can be adjusted so that more or less of the gas anesthetic is administered to the patient . This feature allows the anesthetist to adjust the level of anesthesia as needed (more if the patient is too light and less if it's too deep).

General anesthesia

. General anesthesia refers to a level of anesthesia in which the patient is completely unresponsive to noxious (harmful) stimuli and in which surgery can be performed . Animals feel pain just like humans do, so it's necessary to bring them to a level of anesthesia that allows the veterinarian to do surgery without causing pain . Two phases of general anesthesia exist: the induction phase and the maintenance phase . Induction is the phase in which the patient is given drugs to cause muscle relaxation and put the patient into a level of general anesthesia . Maintenance is the phase in which the animal is kept at a level of general anesthesia that lasts long enough to complete the surgery.

Operative Record Keeping pt3

. Generally, it's most important to follow trends regarding these parameters . For instance, if the patient's heart rate is consistently decreasing each time it's checked, the animal might be too deeply anesthetized . If it's consistently increasing each time it's checked, the anesthesia might be too light and the patient might be experiencing pain . This latter scenario could also mean that the animal's blood pressure is decreasing and the body is increasing the heart rate to compensate. . The ideal situation—one in which each vital parameter stays essentially the same each time it's measured—typically indicates a stable patient who is being properly anesthetized and is responding well to the surgical procedure.

Intravenous Fluids pt3

. Giving intravenous fluids during surgery also helps keep the intravenous catheter open and functional . The IV catheter must be patent (not occluded or clogged) in case it's necessary to give the animal IV drugs during or after surgery . These drugs may be either antibiotics or emergency drugs (if the animal has a problem while under anesthesia).

Preparing the Surgical Site Using Aseptic Technique pt2

. Hair is usually best removed using electrical hair clippers with fine cutting blades that allow removal of the hair at the skin surface . Number 40 clipper blades are usually used in small animals, and number 10 blades in large animals . It's important to know where the surgical incision will be so you know where to clip . For instance, spay incisions are usually in the middle to the caudal part of the abdomen, and incisions to remove foreign bodies from the stomach are usually in the cranial part of the abdomen . Make sure that enough hair is removed from around the proposed incision site to reduce the risk of contamination.

Intravenous Catheter Placement pt2

. IV catheters frequently used for surgery are "over-the-needle" catheters, in which the plastic catheter sits over a metal needle . The function of the needle is to puncture the skin and the wall of the vein . The catheter is then slid over the needle into the vein . Tape is usually used to hold the catheter to the vein . A cap can be placed into the open end of the catheter to prevent blood from coming out . Most caps are rubber and allow a syringe needle to be inserted through them so that drugs can be administered through the catheter and into the vein . IV catheters also allow intravenous fluids to be administered during surgery.

Preparing the Surgical Site Using Aseptic Technique

. Ideally, preparing the surgical patient begins the day before the surgery by bathing the animal and clipping its hair from the proposed surgical site . However, in most cases, all of the preparation is done the day of the surgery . After the animal has been anesthetized, its hair is clipped from the surgical site . This is one of the main surgery- related jobs of the veterinary assistant . Clipping of hair is done in the surgery preparation room . Hair shouldn't be clipped in the operating room since it can act as a source of contamination.

Anesthetic Procedures and Equipment

. In general terms, anesthesia means the loss of sensation with or without the loss of consciousness . There are many ways for the veterinarian to anesthetize, many substances from which to choose, and proper doses for each patient and procedure . The choices made depend on the type, size, and condition of the animal and the type of surgery . In addition to anesthetics, veterinarians use analgesics, which decrease sensitivity to pain without the loss of consciousness, and sedatives, which relax the patient . A variety of administration and monitoring procedures and equipment are used to maximize the positive effects and reduce the risks of anesthesia.

Induction drugs

. Induction drugs are given so that the animal is at a level of anesthesia deep enough that an endotracheal tube can be placed . With you holding the patient, the veterinarian or veterinary technician will administer the induction drug (or drugs) . In most cases, the patient's body will relax as he or she comes under the influence of the drug . You'll need to be extra vigilant at this point . Since the animal isn't able to help hold itself up, it may roll off of the table if you aren't supporting it sufficiently . Next, the person administering the anesthesia checks the animal to see if the depth of anesthesia is sufficient to allow placement of the endotracheal tube . Jaw tone, or the ability to easily open the animal's mouth (without the animal fighting you), is an important parameter to assess the depth of anesthesia . If the animal is anesthetized enough, you'll be asked to hold open its mouth.

Induction

. Induction is usually carried out using liquid anesthetic agents given intravenously . Drugs used to induce anesthesia include ketamine and diazepam, a narcotic and tranquilizer combination, and propofol, a newer, ultra-short-acting injectable drug . A desirable characteristic of propofol is that its effects aren't cumulative (i.e., the drug can be given more than once in a short period without a great risk of overdose), so it can be used as both an induction and maintenance drug . For propofol to act as a maintenance anesthetic, the drug is administered intravenously either as a repeated bolus (mass) or as an infusion (slowly and continuously, usually by machine) . This method of general anesthesia is usually employed when the procedure is very short (as in a cat castration, for example).

Preparing the Surgical Site Using Aseptic Technique pt4

. Instead, use a new sponge to repeat the process. . Scrubbing the skin too hard might make the skin bleed more at surgery and might make it more susceptible to infection—so be gentle. . The scrub is complete when all gross contamination is removed from the surgery site . Look at the sponges after they're used to scrub the skin . If dirt is visible on the sponge after scrubbing, the gross contamination isn't yet completely removed . The animal is then moved into the surgery room, hooked up to the anesthesia machine (if not already done), and positioned for surgery . The surgery site is then rescrubbed . A total of three to five minutes of gentle scrubbing is standard . After the site has been scrubbed with soap, the site is usually sprayed with an antiseptic solution (again, chlorhexidine or povidone-iodine).

Intravenous Catheter Placement pt3

. Intravenous catheters come in a variety of sizes. The size of an IV catheter is defined as its gauge . The larger the number gauge an IV catheter is, the smaller its diameter is . For instance, a 25-gauge catheter is smaller than a 20-gauge catheter . The most commonly used sizes in small-animal veterinary medicine are 25 gauge (used in small dogs and cats), and 22, 20, and 18 gauge . (18-gauge catheters are typically used in large dogs, such as Great Danes.) . In large animal veterinary medicine, 16-gauge and 14-gauge catheters are commonly used.

Intravenous Fluids

. Intravenous fluids are given during many surgeries to help maintain the patient's blood pressure . Most anesthetic agents have some effect on the blood pressure of the animal . Most lower it to some degree . In addition, many surgeries are associated with some blood loss, which also has an effect on blood pressure . Maintaining blood pressure is vital to the health of the animal . If the pressure is too low, appropriate blood flow to vital organs (heart and brain, for example) is jeopardized.

Operative Record Keeping pt4

. It's a very good idea to have a form that allows organized monitoring and recording of these signs . This form usually also contains other information about the patient, such as how much and what kind of anesthetic drugs were given and how much blood was estimated by the surgeon to be lost during the surgery . It's the anesthetist's job to monitor many of these parameters . However, it may be your responsibility to fill in the appropriate patient information.

Positioning the Patient pt4

. Large animals are positioned in a similar way to small animals but require larger surgery tables and ropes . In addition, large animals, because of their weight, are susceptible to muscle damage if they're placed on a table that isn't sufficiently padded . The damage occurs after pressure on the muscle forces the blood out of the muscle, resulting in a series of metabolic changes that can cause severe pain . More seriously, chemicals from the damaged muscle can produce kidney damage . Placing sufficient padding under the animal before surgery eliminates this potential problem.

Intravenous Catheter Placement

. Many older or sick animals, or animals undergoing a lengthy or complicated surgery, require intravenous fluids during the procedure . An intravenous catheter is placed in a peripheral vein to allow access to the blood system . The vein of choice in small animals is most commonly the cephalic vein in the front leg or the saphenous vein in the hind leg . In horses, the jugular vein in the neck is most frequently used.

Collecting, Storing, and Shipping Samples

. Many times, samples collected at surgery or from a necropsy are sent to a pathologist to perform a biopsy (a microscopic examination of a tissue or organ to look for disease) . The tissue sample is usually preserved in formalin . Formalin is a 3.7% solution of formaldehyde that can be used to preserve any tissue type . This solution keeps the tissue sample from degrading before it's analyzed by the pathologist . The tissue sample is placed in a container with formalin in it. . Ideally, the tissue sample should be no more than 0.75 cm in thickness when placed in the formalin . (A greater thickness might prevent the formalin from penetrating into the deepest part of the tissue sample.) . The total volume of formalin compared to the volume of the tissue sample should be 10:1 . A lower ratio might prevent the complete fixation of the entire tissue sample. . The container, which must be tightly sealed (usually with a twistable lid), is then sent to the pathologist, usually through the mail . Most pathology labs have prepared formalin containers and an established method for forwarding containers.

the veterinarian will talk to the client about the care of the pet

. Most of the time, the veterinarian will talk to the client about the care of the pet (for instance, if talking about a surgery, the discussion might cover how anesthesia is done, the specifics about the surgery itself, the possible risks, the postsurgical care, and so on) . Your role might be assisting the veterinarian in doing preoperative blood work or, for less involved cases, in helping to hold a dog for administering a vaccine or toenail cutting . In any event, it's important that you're able to demonstrate to the owner both competence and compassion . The owner must feel that his or her animal is in good hands and will receive good care.

admissions

. Most practices require the owner to sign an admissions form that states what will be done to the animal, explains the possible complications, and provides an estimate of costs . Most practices also require the owner to leave a deposit, especially if the treatment will be expensive . When the patient is properly admitted to the hospital, you'll probably assist the veterinarian or the veterinary technician in preparing the patient for surgery . You might be involved in assisting with drawing blood for analysis, placing an intravenous catheter, and/or starting the animal on intravenous fluids . The remainder of this assignment describes a number of surgical procedures that you'll likely see and with which you'll be involved in your role as a veterinary assistant.

Most veterinary assistants play a role in admitting patients to the veterinary hospital

. Most veterinary assistants play a role in admitting patients to the veterinary hospital, either for medical treatments or surgery . After the veterinarian has talked to the owner about the animal's treatment, most practices follow a standard procedure to officially admit the patient to the hospital . Your role often involves taking the animal to its cage and possibly taking the owner to the receptionist to complete paperwork . In some cases, you may be responsible for making sure the paperwork is completed by the owner.

Commonly Performed Surgeries

. One of the most important aspects of veterinary medicine is the relationship between a veterinarian and his or her clients . A close emotional bond exists between an owner and his or her pet . For the owner to feel comfortable allowing the doctor to care for an animal, a trusting relationship must exist between the owner and the veterinarian . As an employee of the veterinarian and a valued member of the veterinary practice team, you, the veterinary assistant, are a part of this relationship.

Asepsis and Operating Room Conduct pt2

. Only the people who are necessary for the surgery should go into the operating room . Traffic into and out of the operating room should be kept to a minimum so that dirt and debris aren't brought into the room . Try to keep your movements in the room to the minimum required to do your job . Also, avoid talking as much as possible . Usually, the surgeon sets the tone for the surgery room, and you should follow this pattern of conduct . Some surgeons don't like talking or noise during the procedure . Others are more talkative or like music played during surgery.

Orthopedic Procedures

. Orthopedic surgeries, which involve bones or joints, include repairing a broken bone, stabilizing a joint with a ruptured ligament, or removing a tumor from a bone . These surgeries are most commonly performed in dogs, cats, and horses. . Even recently, broken bones in horses meant certain death, but now they can be successfully treated . Likewise, dogs and cats with broken legs or with damaged joints can be successfully treated, often using the same sophisticated bone pins and bone plates used in people . Cows, sheep, and pigs, if they're valuable enough to their owners, also can benefit from surgeries to repair broken bones or dislocated joints. . Orthopedic surgeries, in small and large animals, are always performed under rigid aseptic technique and always in a surgery room (unlike some soft-tissue procedures in cows and other large animals that are sometimes more easily done in the animal's stall).

Handling Rabies Suspects and Samples

. Rabies is an extremely serious viral disease that can affect all animals, including people . The virus attacks the nervous system of the animal, causing it to shut down . After the virus invades the nervous system, it's always fatal . The virus usually spreads when an infected animal bites another animal, but it can potentially spread by direct contact with infected tissues. . The only way to identify if an animal has or had rabies is to do a biopsy on the brain of the animal to see if there are characteristic changes . When testing for rabies, the entire brain of the animal is sent to a special laboratory for testing . The veterinarian must carefully remove the brain from the animal and seal it in two plastic bags . The sample is sent refrigerated (not frozen and not in formalin) to the laboratory . The lab will then send a report indicating whether the sample tested positive or negative.

Disposal of Deceased Animals pt2

. Since some owners wish to see their pet's body before it's buried, the body must be made presentable before it's placed in the bag and box . In this case, blood and bodily fluids are cleaned, the eyelids are usually closed, and wounds are cleaned or at least covered or closed . All of these steps are taken to make the animal look as close to "normal" as possible so that the owner isn't shocked to see the body . This is a very emotionally difficult time for most owners, so anything that can be done to ease their emotional burden should be done. . Regardless of which method of disposal is chosen, it's important to keep records of all deceased animals and especially important to make sure that the disposal company handles the body according to the wishes of the owner.

Preanesthetic Preparation pt2

. Step 5: Close the pop-off valve and pressurize the breathing system using the oxygen flush valve. A pop-off valve is an escape valve that prevents the pressure within the anesthetic machine from building up too high. Place your thumb over the patient connection. If no leaks are present, the system should maintain pressure. . Step 6: Open the pop-off valve. . Step 7: Attach the breathing system to the waste gas scavenging system. . The anesthetic machine must be checked to make sure that there's enough oxygen and gas anesthetic available, all tubes are properly connected, and the devices that collect waste anesthetic gasses are in proper working order . You should also check to make sure that all of the supplies—the endotracheal tube, gauze to tie the tube to the animal, intravenous catheter, and the lubricant to keep the patient's eyes from getting dry—as well as the anesthetic drugs, are available . When all of the equipment and supplies are checked and available, the patient is brought to the preparation area to be anesthetized.

Positioning the Patient pt3

. Surgery on the legs (to repair a broken femur or a torn knee ligament) is usually done with the animal lying on its side, with the operated leg up . In many cases, the operated leg is "hung" (temporarily held up off the table by tying it to an IV pole, for example) during preparation for surgery . By keeping the entire leg up off the table, it can be completely scrubbed for surgery . After the leg is scrubbed, the surgeon will grasp the leg in a way that maintains sterility, and the leg will be "cut down" from the pole to allow draping . Although it's not always necessary to tie the animal to the table when it's placed on its side, this is sometimes done just to keep the other legs out of the way.

Tail Docking

. Tail docking, the surgical removal of a part of the tail, is typically done at a very early age—at two or three days in dogs and within the first few weeks of life in sheep . In some breeds of dogs (such as Doberman Pinchers and Rottweilers), tail docking is done solely because breed standards indicate that the dog "must" have a short tail . There's no medical reason to dock a dog's tail (unlike tail amputation, which is usually done in older animals with a disease, such as a tumor, affecting the tail) . A lamb's tail is usually docked to keep it from getting dirty and traumatized.

Intravenous Catheter Placement pt5

. The animal must be held securely to prevent it from moving the leg while the catheter is being placed . The person holding the animal also "holds off" the vein . This means that your finger places pressure on the vein higher up on the leg than where the catheter is placed . This procedure "backs up" the blood in the vein, making the vein stand out more so that the catheter can be placed more easily. . The catheter is secured to the leg with tape, and the fluids are connected to the catheter . Intravenous fluids come in plastic bags or glass bottles . Tubing is used to connect the bag or bottle to the IV catheter.

Operation and Maintenance of Suction and Cautery Machines pt3

. The cautery machine also needs minimal maintenance . It should be cleaned at the end of the day, and its electrical components should be periodically checked . Most units use a ground plate, which is placed in contact with the patient and connected to the machine . The ground plate allows electrical current to pass through the animal's body so that the patient doesn't receive an electrical shock . The ground plate must be checked periodically to make certain that its wire isn't frayed or broken.

Passing Instruments and Supplies pt4

. The circulating nurse also collects and properly handles any specimens collected by the surgeon during the procedure . These specimens may be tissue samples to be submitted for biopsy or bladder stones to be submitted for analysis . The circulating nurse receives the specimen and then places it in the appropriate container . (For example, tissue samples for biopsy are placed in a formalin container.) . The container must be labeled with the patient's name. . A pathology submission form is usually filled out so that the sample can be properly processed . The information that needs to be included on this form includes the doctor's name; owner's name; patient's name; patient's breed, age, and sex; the type of tissue included; and a summary of the patient's history and clinical signs . Most hospitals also keep a separate log of all samples submitted to laboratories for analysis.

Positioning the Patient pt2

. The legs are held in position using rope, which is tied to the leg and then tied to the surgical table, as follows: 1. The rope is pretied to form a slip knot at one end. 2. The rope is double-looped on the leg (for instance, the slip knot is gently tightened at the wrist level of the front leg). 3. A second half-loop is then slipped over the midpaw. 4. The free end of the rope is then tied to the table. . The double loop distributes the force that's applied by the rope to the leg over a greater area—reducing the risk of cutting off circulation to and from the foot . Still, it's very important to make certain that the rope isn't tied too tightly to the leg . Rolled or folded towels or sandbags also can help support the patient in the desired position.

Operation and Maintenance of Suction and Cautery Machines pt2

. The machine itself needs minimal maintenance. The collection container should be emptied of any collected fluids and cleaned . The machine should be periodically checked to make sure the electrical components are working correctly. . A cautery unit allows electrical current to be transmitted to a blood vessel . This current cauterizes the vessel and stops it from bleeding . Hemostasis (stopping of bleeding) occurs through heat-induced protein denaturation (elimination of protein's biological activity) and tissue coagulation (thickening or clotting) . A cautery unit can be used to stop bleeding in arteries up to 1.0 mm in diameter and veins up to 2.0 mm in diameter . Instead of using a regular scalpel blade, some electrocautery units can also be adjusted to cut tissue . By coagulating small blood vessels as it cuts tissue, the unit reduces the amount of bleeding.

Care of Exposed Tissues and Organs

. The most common problem of tissues or organs exposed to air during surgery is drying . Drying, associated with dehydration of the cells of the tissues, can interfere with cellular function and can result in cellular death . Contact with air allows evaporation, which is increased by hot surgery lights . All exposed organs or tissues that aren't being directly worked on should be covered with a surgical sponge moistened with sterile saline solution . This task is usually the responsibility of the surgical assistant. . For tissues that are being worked on, it may be necessary to intermittently pour some saline solution onto them . The solution is usually applied using a sterile syringe or a bulb syringe. . It's also important to protect exposed organs from injury . For instance, if the spleen has been moved out of the abdomen and onto the outer body wall, you must be careful not to lean on it or bang it with instruments . Always be aware of the location of all instruments, supplies, tissues, and organs to minimize the risk of contamination or damage.

Passing Instruments and Supplies pt3

. The package in which the instrument is kept must be opened carefully so that the instrument isn't contaminated. . The instrument is then passed to the surgeon or placed on the table in such a manner as to prevent contamination . Usually, the package is opened slightly over the surgical table and the instrument is allowed to gently fall onto the table . It's important to open the package carefully, because if the instrument is contaminated as it falls onto the table, it will contaminate the entire table and, potentially, all of the instruments on it.

Positioning the Patient

. The patient's position on the surgery table (or on the floor, in large- animal surgery) depends on the surgical procedure being performed . In most cases, a safe warming device such as a warm water blanket is placed on top of the table and under the patient to help keep it warm during surgery . Most abdominal surgeries are performed through a ventral midline incision, which is an incision made in the middle of the caudal part of the abdomen . For this procedure, the animal is typically positioned on its back, with its front legs pulled forward and its hind legs pulled backward

pop-off valve

. The pop-off valve prevents excess pressure in the anesthetic machine . Certain anesthetic regimens are associated with high flows of oxygen (high-flow anesthesia), which can rapidly produce dangerously high pressures within the system that could prevent the patient from breathing . In this instance, the pop-off valve is set to open to allow the excess pressure to be vented off . In anesthetic regimens where the oxygen level is set lower (low-flow anesthesia), the pop-off valve is kept closed, since the pressure within the system shouldn't interfere with the patient's ability to breathe.

Passing Instruments and Supplies pt2

. The surgery table should always be kept clean and the instruments in a specific location . The surgical assistant may know the location of each instrument, and therefore can find it and pass it to the surgeon quickly . If the assistant works with a surgeon long enough, he or she will learn to anticipate the surgeon's needs . A good surgical assistant often passes an instrument to the surgeon before he or she has asked for it. . The circulating nurse is the person who gets whatever the surgeon needs from the supply area . As a veterinary assistant, you might function as the circulating nurse . For instance, if the surgeon needs another instrument or suture material, the circulating nurse retrieves it from the storage area . This person either gives the instrument or material to the surgeon (or surgical assistant) or places it on the surgery table.

laryngoscope

. The veterinarian or technician usually uses a laryngoscope to assist with endotracheal tube placement . A laryngoscope is a battery- operated instrument with a small light at the end of a blunted metal blade . The blade is used to push down on the animal's tongue and hold the epiglottis out of the way . The epiglottis is a V-shaped structure that normally sits just in front of the opening of the larynx (the upper part of the trachea that contains the vocal cords) . As a veterinary assistant, it may be your responsibility to make sure that all the equipment needed for endotracheal intubation is present and in good working order.

Passing Instruments and Supplies

. The veterinary technician serves as the sterile surgical assistant and scrubs with the surgeon and assists him or her with the actual surgical procedure . The assistant passes instruments to the surgeon, retracts tissues, holds organs as needed, and cuts the ends of the suture material after the surgeon makes the knot . Each surgical instrument should always be handed to the surgeon in a manner that allows the surgeon to use it without readjusting it . For instance, scissors should be handed handle side first. . After asking for an instrument, the surgeon usually holds his or her hand out fully open . The surgical assistant places the instrument in the surgeon's hand with a somewhat firm slap . This practice ensures that the surgeon knows the instrument is in her or his hand.

There are two basic systems for anesthetic gas administration

. There are two basic systems for anesthetic gas administration: in-the- circuit (also called in-circle) and out-of-circuit (also called out-of-circle) . With in-circle anesthetic machines, the vaporizer is located within the breathing circuit, so that the amount of gas delivered is generated by the patient's breathing . With out-of-circle anesthetic machines, the vaporizer is outside the breathing circle, so the amount of gas administered is determined by the oxygen flow. . Which system is used depends on the type of anesthetic agent used . Out-of-circle machines, which allow precise administration of gas anesthetics, are used with highly volatile anesthetics . Both isoflurane and halothane are used with out-of-circle machines. In-circle machines use the anesthetic methoxyflurane.

Induction and Maintenance of General Anesthesia

. When the catheter is in place, anesthesia is given. In most cases, two types of drugs are given . An induction agent, usually a liquid, anesthetizes the animal enough so that a tube can be placed in its trachea . A maintenance agent, usually a gas anesthetic given through the endotracheal tube, has effects that last for the entire surgery.

Intravenous Catheter Placement pt4

. Your role as a veterinary assistant will be to hold the animal while the veterinarian or veterinary technician places the catheter and to understand what equipment is used to set up for the procedure . The site where the catheter is placed is clipped of hair . You, or, more commonly, the person (veterinarian or technician) who is placing the catheter, will do this . Usually, an electric clipper is used to remove the hair over the vein to the level of the skin . The skin is scrubbed with an antiseptic solution such as chlorhexidine or povidone-iodine.

Anesthetic machine must

1. Be filled with anesthetic agent 2. Be connected to oxygen source 3. Have clean anesthetic tubing (clean after each use) 4. Have all tight connections (no leaks from any tubing or connections) 5. Have functional CO2 and gas anesthetic absorption/disposal systems 6. Have cleaned rebreathing/reservoir bags

laryngoscope pt2

Follow these steps. - Step 1: Choose two or three tube sizes for each patient in case the first is too large or too small. Use a sterile syringe to inject air into the cuff of the endotracheal cuff to check the cuff's ability to hold volume. - Step 2: Choose an appropriate-size stylet if needed to aid intubation with small-diameter or very flexible tubes. - Step 3: Choose a topical anesthetic agent, which, if needed, can facilitate intubation with minimal trauma. - Step 4: Cut or tear a length of gauze to secure the endotracheal tube to the animal's head. - Step 5: Prepare the laryngoscope. Choose the appropriate-size blade and secure it to the handle of the laryngoscope. Be sure the light is functional. - Step 6: Prepare sterile lubricant if needed to make the passage of the tube easier.