Medical Nursing in Veterinary Medicine

Medical Nursing

In veterinary medicine, orogastric intubation is performed on canines to feed neonates that lack a suckeling reflex or cannot nurse. This procedure is also used to decompress the stomach in the case of gastric dilation-volvulus (GDV) or to perform gastric lavage after a toxin ingestion. In neonate puppies, a small tube is measured from the tip of the nose to the last rib. That point is marked and the tube is advanced down the back of the puppy’s throat to the marking. Neonate puppies do not have gag reflex, so they will not cough or gag when the tube is placed. To determine the tube has been placed down the esophagus and not the trachea, make sure the tube is advanced to the marking on the tube. If it cannot be advanced to the marking, the tube may be in the trachea. Slowly administer the appropriate amount of formula. Once the puppy is fed, pinch the tube (to prevent any fluid from entering the trachea) and slowly remove it (McCurnin, 2014).

Most dogs tolerate placement of an orogastric tube (OGT) without sedation and with little resistance. However, if the dog is intolerant or trying to bite, sedation may be required. If orogastric intubation is being performed on a sedated dog, the airway can be secured by placing an endotracheal tube (ETT). To perform orogastric intubation, the dog should be placed in a sternal or standing position. A plastic or rubber tube is measured and marked with a marker or tape from the tip of the nose to the last rib. A roll of tape (or something with a hole in the center large enough to pass the tube through) is placed in the dog’s mouth to hold the mouth open. The end of the tube is lubricated and slowly passed through the hole in the roll of tape. The dog may swallow as the tube enters the esophagus. This is normal. If the dog coughs, the tube may have entered the trachea and should be removed (McCurnin, 2014).

Once it is determined that the tube has entered the esophagus, it should be advanced slowly to the marked point on the tube. If an endotracheal tube has been placed, then there is little concern for aspiration. However, if an ETT was not placed, the OGT should be checked to make sure it is in the esophagus and not the trachea. In order to do this, air can be blown into the OGT and bubbles can be heard in the stomach with a stethoscope (McCurnin, 2014). If performing a gastric lavage, the dog should be in sternal or right lateral recumbency. Fluid should be introduced into the tube via a syringe, funnel, or pump. Palpate the stomach to break up stomach contents and to confirm that the stomach is not being overfilled with fluids. Lower the tube into a bucket to allow stomach contents to be emptied. In the case of toxin ingestion, activated charcoal can be added after the stomach has been lavaged. When removing the tube, kink the end and slowly pull the tube out of the esophagus. Kinking the tube prevents the backflow of fluids into the trachea. (McCurnin, 2014).

The main risk associated with orogastric intubation is advancing the tube into the trachea instead of the esophagus and causing aspiration. Administering an antiemetic prior to performing a gastric lavage will decrease the risk of secondary aspiration. (Mollderm).When assessing the hydration status in a feline patient, several parameters should be measured. Capillary refill time (CRT) is the most important indicator of hydration, followed by mucous membranes and turgor pressure. Capillary refill time is important because it reflects the patient’s cardiac output. Cardiac output refers to the amount of blood pumped by the heart per minute. Dehydration affects cardiac output, which is why CRT’s are used to measure hydration in animals. It is performed simply by pressing a fingertip to the animals gums until they turn white. When the fingertip is removed, the time it takes for the color to return to normal is observed. A normal CRT should be less than 2.5 seconds. A prolonged CRT greater than 2.5 seconds is indicative of dehydration or shock (McCurnin, 2014).

The condition of mucous membranes, such as the gums and eyelids, can also be beneficial in assessing a patient’s hydration status. Patient’s that are well hydrated have mucous membranes that are pink and moist. The mucous membranes of a dehydrated patient are usually dry and tachy. Turgor pressure is essentially a skin pinch test. The skin is pinched (usually behind the shoulder blades) and released. The amount of time it takes for the skin to return to its normal position is considered the turgor pressure. The normal turgor pressure of a well hydrated animals is one second or less. Prolonged turgor pressure of greater than one minute is considered dehydrated. Approximate ranges are 2-4 seconds is about 5-8% dehydrated, 5-10 seconds is about 8-10% dehydrated, and 10-30 seconds is about 10-20% dehydrated. Obese patients can have a false turgor pressure, as the fat tends to allow the skin to fall back down quicker (McCurnin, 2014).

There are three phases of fluid therapy. Resuscitation, replacement, and maintenance. As the female feline is not showing signs of shock, the resuscitation phase is not necessary. We will begin fluid therapy at the replacement phase to treat the dehydration. To calculate the replacement rate of fluids, we will first determine the fluid deficit. This is calculated by multiplying the patient’s body weight in kilograms by the estimated percent dehydration as a decimal. In the case of the 8 lb female cat that is 10% dehydrated, the cat’s weight in kilograms is 3.64 kg (8 lbs divided by 2.2), which is then multiplied by 0.1 (10% expressed as a decimal). 3.64 kg x 0.1 equals a fluid deficit of 0.36 L (360 mL). To replace the 360 mL fluid deficit in 24 hours, the patient needs to receive 15 mL per hour (2013 AAHA/AAFP Guidelines).The next step is to determine ongoing losses (vomiting, diarrhea, bleeding, etc.). As the cat does not have any of these, ongoing losses are not a factor (loss from urination is accounted for in the final calculation). The final calculation is the maintenance rate. The formula for the maintenance rate in cats is 80 x body weight (kg)^¾ per 24 hours. In this case, the maintenance rate is 211 mL/24 hrs or 8.79 mL per hour. The fluid deficit is added to this amount, making the fluid rate 23.8 mL per hour (2013 AAHA/AAFP Guidelines).After hydration status has been corrected, we can begin the maintenance phase of fluid therapy. This is determined by again calculating the maintenance rate (80 x body weight (kg)^¾). In this case, the maintenance rate is 211 mL/24 hours or 8.8 mL per hour. As the patient starts to show signs of recovery, this rate can slowly be decreased.

IV fluid therapy should be monitored closely and often. Skin turgor, mucous membranes, and overall appearance should be checked often to assess hydration status. PCV and body weight should also be checked often (2013 AAHA/AAFP Guidelines).It is important to carefully monitor patients undergoing fluid therapy because it is possible for a patient to receive too much fluids. An excess of fluids can cause volume overload, which can cause pulmonary edema and cavitary effusion. Respiratory rates, patterns, and thoracic auscultation should be checked and performed often. If pulmonary crackles are detected or if the respiratory rate increases, fluids should immediately be stopped and a veterinarian should be notified (McCurnin, 2014).There are two different forms of dental structures in animals, brachyodont and hypsodont. Dogs have brachydont teeth, meaning they have a small crown compared to the roots. The root apex is open during development. Because of this, the teeth do not continue to grow after eruption. Horses have hypsodont teeth, meaning they have a large crown beneath the gingiva and root, which allows constant growth throughout the animals life (McCurnin, 2014).

Dental prophylaxis is performed in dogs in order to clean the teeth by removing tartar, calculus (hardened plaque), and cleaning under the gingiva. It is also performed to assess the extraoral (external) and intraoral (internal) structures. Thorough dental examinations under sedation and dental radiographs can find issues and conditions that the owner may not have been aware of, such as unerupted teeth, retained deciduous teeth, broken teeth, oral fistulas, abscesses, and cancer. It is important that canine patients receive a dental prophylaxis at least once a year (in some cases twice a year). Dental prophylaxis should be performed not only to examine the internal and external oral structures, but also to clean the teeth and remove bacteria. Bacteria can cause damage not only to the teeth and oral cavity, but systematically to the rest of the body and organs (Gorrel, 2014).

Since horses have hypsodont teeth, their teeth are growing and erupting throughout their entire life. As this occurs, sharp points are formed along the edges of the teeth. This condition makes it painful for horses to eat, causing them to drop their feed. When this happens, they can lose weight and become ill. That is why horses, just like dogs, require dental care at least once a day (in some cases twice a year). Dental prophylaxis in the equine patients is referred to as a float. A float is essentially when the veterinarian files down the sharp points and edges of the teeth. By smoothing the tooth surface, horses can eat pain free. Other benefits of annual dental prophylaxis is checking for abnormalities and conditions, such as retained deciduous teeth, broken teeth, jaw abnormalities, abscesses, cancers, and infections (McCurnin, 2014).

There are major differences between how a dental prophylaxis is performed in canine and equine patients. In canines, the teeth are cleaned by scaling the teeth, either with an ultrasonic scaler or manual scaling. This process removes tartar and calculus from the tooth’s surface and cleans under the gingiva. The gums are also probed for pockets. Gingival pockets are cleaned with a curette (unless the pocket is so deep it requires alternate treatment or extraction), which removes the tartar and bacteria. After the teeth are cleaned and the assessment is complete, the teeth are polished. Polishing the teeth creates a smooth surface, making it more difficult for bacteria to adhere to. By contrast, dental prophylaxis in the equine patient is filing down the points and the teeth. The points are files to create a smooth surface or to balance the teeth (McCurnin, 2014).

Cardiopulmonary resuscitation (CPR for short) refers to the resuscitation efforts made after an animal has suffered cessation of heart and respiratory function (cardiopulmonary arrest). The goal of CPR is to restore the perfusion of blood to the body and oxygen to the respiratory system. When cardiopulmonary arrest occurs, the first step is to check the ABC’s, which are airway, breathing, and circulation. The airway is checked by opening the pet’s mouth and pulling out the tongue. The oral cavity and trachea should be inspected for any foreign material that could be obstructing the airway (such as a vomit, blood, or a foreign object). Anything obstructing the airway should be removed. The next step is to check the respiration and pulse of the animal. If neither are present, CRP should begin immediately (McCurnin, 2014).

CPR should begin immediately with chest compressions. The animal should be laid in the proper position for its size and shape. Cats and small dogs should be placed laterally with both hands wrapped around the animals chest. Compressions are performed by squeezing the thumb and fingers together. Average sized dogs should be placed laterally, with both hands placed over the highest point of the chest. For keel (narrow) chested dogs, both hands are placed lower over the chest, closer to the sternum. Barrel chested dogs are positioned dorsally, which both hands placed over the center of the sternum. Once the animal is positioned properly, compression should begin. The rate of compressions should be about 120 beats per minute. The chest should be compressed ½-1/3rd the width of the chest. Allow for a full recoil of the chest before performing the next compression. The ratio should be 30 compressions per 2 breaths. CPR should be performed continuously for 2 minutes without interruptions, which allows for 4 sets of compressions and breaths before checking the animals ABC’s again (D’Andrea, 2015).

While compressions are being performed, the patient should be intubated in order to secure an airway. This is performed by placing the correct size tube into the trachea. Once proper placement has been achieved, an oxygen source should be connected and manual breathing should begin. As intubation and ventilation are being performed, another staff member should be securing venous access in order to administer emergency drugs and fluids. This should be done by placing a IV catheter into the most accessible vein. If a vein cannot be secured, certain drugs can be administered via the endotracheal tube.

These drugs include Naloxone, Atropine, Vasopressin, Epinephrine, and Lidocaine). Drugs that are administered this route should be flushed with saline to insure the drugs have passed through the tube (McCurnin, 2014). An emergency crash cart is where most of the items needed for emergency resuscitation are kept. They are generally kept in the same area for easy reach in an emergency situation and are mobile. Most crash carts include various emergency drugs, needles, syringes, IV catheters, IV lines, a laryngoscope, endotracheal tubes, ambu bag, and something to secure the endotracheal tube and IV catheter. A heart monitor, stethoscope, and oxygen source should also be within reach (McCurnin, 2014).

References:

1. AAHA/AAFP Fluid Therapy Guidelines for Dogs and Cats. https://www.aaha.org/public_documents/professional/guidelines/fluidtherapy_guidlines_toolkit.pdf.
2. D'Andrea, Amy. Canine and Feline CPR and First Aid Manual. Canine and Feline CPR and First Aid Manual, Pet Emergency Education, LLC, 2015.
3. Gorrel, Cecilia, et al. Veterinary Dentistry for the General Practitioner. 2nd ed., Saunders Elsevier, 2014.
4. Molldrem, Alex. How to Perform Gastric Lavage. https://vetgirlontherun.com/veterinary-continuing-education-how-perform-gastric-lavage-dog-vetgirl-video/
5. McCurnin, Dennis M., et al. McCurnin's Clinical Textbook for Veterinary Technicians. 8th ed., Elsevier Saunders, 2014.