Ins and outs of feeding tubes (Proceedings)

Addressing the nutritional needs of our hospitalized and critical care patients can dramatically improve their outcomes, but also allows them to return home sooner. Oral enteral nutrition is the ideal route, but if the patient is unable or unwilling to consume at least 85% of their calculated resting energy requirements (RER) than another route needs to be utilized.

Nasoesophageal/Nasogastric tube placement

When oral nutrition is not an option, what other options are available? There are a number of feeding tube options available, the choice of tube will be dependent on the condition of the patient, the disease being addressed, and expense of administration, availability of intensive care facilities, the preferred food and anticipated length of feeding assistance.

The first step would be to calculate the RER for the individual patient. The most widely used formula is: (weight in kilograms X 30) + 70 = RER. This formula can be utilized in both cats can dogs over 2 kilograms to 45 kilograms. (1, 2, 3) Alternately, for cats you can use: (weight in kilograms × 40) = RER. For animals that are below 2 kilograms or above 45 kilograms the logarithmic formula can be used: (weight in kilograms × 70)0.75

The best feeding tubes for prolonged use are made of polyurethane or silicone. For short term feeding, usually less than 10 days, polyvinylchloride (PVC) tubes can be used. These are not appropriate for long term feeding because they tend to become stiff with prolonged use causing additional discomfort for the patient. Silicone is softer and more flexible than other tube materials and has a greater tendency to stretch and collapse. Polyurethane is stronger than silicone, allowing for thinner tube walls and a greater internal diameter, despite the same French size. Both the silicone and polyurethane tubes do not disintegrate or become brittle in situ, providing a longer tube life. The French unit measures the outer lumen diameter of a tube and is equal to 0.33 mm.

While force feeding can be used to provide the necessary nutrition, this is usually too stressful to the patient, not to mention the stress to the owner. Seldom is this method able to deliver the volume of nutrients necessary to meet the patients' needs on a regular basis.

Nasoesophageal tubes are useful for providing short term nutritional support, usually less than 10 days. They can be used in patients with a functional esophagus, stomach and intestines. Nasoesophageal tubes are contraindicated in patients that are vomiting, comatose or lack a gag reflex.

Supplies needed include lidocaine drops (ophthalmic drops can be used); 5-8 Fr tube with length sufficient to reach the distal esophagus, sterile lubricant, suture or glue, luer slip catheter plug, and Elizabethan collar.

The length of tube to be inserted is determined by measuring from the nasal planum along the side of the patient to the caudal margin of the last rib. This indicates the ideal tube placement-mark this area with either a piece of tape or permanent marker. After instilling a few drops of the lidocaine into the nose and waiting 10-15 minutes for full analgesic effect, a sterile catheter of sufficient length (8 Fr × 42 inch in dogs > 15 kg, 5 Fr × 36 inch in dogs < 15 kg) is advanced into the nose. The tube should be passed with the tip directed in a caudoventral, medial direction into the ventrolateral aspect of the external nares. The head should be held in a normal static position. As soon as the tip of the catheter reaches the medial septum at the floor of the nasal cavity in dogs, the external nares are pushed dorsally, this opens the ventral meatus, ensuring passage of the tube into the oropharynx. In cats, the tube can be inserted initially in a ventromedial direction and continued directly into the oropharynx. The tube is inserted until the tape tab or marked area is reached. To evaluate proper tube placement, 3-15 ml or sterile water or saline can be injected through the tube and the animal evaluated for coughing. Coughing would indicate the tube is placed in the lungs not the esophagus. Lateral radiographs may also be taken to confirm tube location. After confirmation of position, the tube is secured with either glue or sutures at the external nares and along the dorsal midline along the bridge of the nose. Continue to direct the tube over the head and secure with a bandage around the neck. Place the catheter plug into the catheter. An Elizabethan collar is used in most animals to prevent inadvertent removal of the tube.

Complications include epistaxis, lack of tolerance of the procedure, and inadvertent/ intentional removal by the patient. These tubes should not be used in vomiting patients or those with respiratory disease.

To place a nasogastric tube, follow the same procedure, but measure the length to 3-4" past the last rib. Nasogastric tubes increase the risk of gastroesphageal reflux increasing the incidence of esophageal strictures. This is due to passage through the cardiac sphincter of the stomach allowing reflux of gastric acids into the esophagus.

Due to the small internal diameter of these tubes, only liquid enteral diets can be used. They can either be fed through a syringe pump as a continuous rate infusion or bolus fed. If feeding through a syringe pump, completely change the delivery equipment every 24 hours to help prevent bacterial growth within the system. Tube clogging is a common problem; a syringe pump may help to decrease the incidence as will flushing well before and after bolus feeding. If the tube becomes clogged, replacement may be necessary. Diluting the liquid with water may also help, though this further decreases the caloric concentration of the diet, increasing the volume necessary to meet the caloric needs.

When removing, the tube may be simply pulled out after the glue or sutures are removed.

Esophagostomy tube placement

Esophagostomy tube placement does require anesthesia to perform, but it does not need to be a surgical depth of anesthesia. The animal should be deep enough to allow placement of a mouth gag to protect the placers hand and equipment. The patient should be anesthetized, intubated and placed in lateral recumbency (usually right lateral is easier for placement if you are right handed). The entire lateral cervical region from ventral midline to near dorsal midline is clipped and surgically prepped.

Supplies needed include: Large Kelly or Carmalt forceps, scalpel blade, appropriately sized tube, tape or suture to secure, and luer slip catheter plug.

One technique uses a large curved Kelly or Carmalt forceps inserted into the proximal cervical esophagus. The tip of the forcep is turned laterally and pressure is applied in an outward direction, causing a bulge in the cervical tissue so the instrument tip can be seen and palpated externally. A small skin incision, just large enough to accommodate the feeding tube, is made over the tip of the forceps. In small dogs and cats, the tip of the forceps is forced bluntly through the esophagus, in larger dogs a deeper incision is made to allow passage of the tip of the forceps through the esophagus. The tube is premeasured as with a nasoesophageal tube, except the exit is in the mid to caudal esophagus. A convenient land mark would be the wings of the atlas; the exit hole should be in line with this. The distal tip of the tube is grasped with the forceps, pulled in to the esophagus and out through the mouth, then turned around and redirected into the esophagus. The tube is secured with tape and sutures. A light bandage is applied around the neck, whether to apply triple antibiotic ointment to the site is an individual choice. Place the catheter plug into the catheter. There are also tube placement systems commercially available for esophagostomy tube placement.

Complications include tube displacement due to vomiting or removal by the patient, skin infection around the exit site and biting off of the tube end by the patient after vomiting.

Depending on the technique used and the size of the patient, an 8 Fr-20 Fr catheter may be used, the large bore of these catheters allow for feeding of a gruel recovery diet, sometimes without dilution with water. These catheters are also easy for clients to use and maintain as long as vomiting is not a problem.

When removing, the tube may be simply pulled out after the sutures are removed. The exit hole is allowed to heal by second intension. A light bandage may be applied for the first 12 hours.

Gastrostomy tube placement

Gastrostomy tubes can be placed either endoscopically, blindly or surgically. All three techniques require general anesthesia, again this does not need to be a surgical depth of anesthesia. Endoscopic placement allows for visualization of the esophagus and stomach as well as biopsy collection from the stomach and proximal duodenum and foreign body removal. Blind biopsy allows placement of a gastrostomy tube without the investment in an endoscopic unit. Surgical placement is useful during surgical exploratory or when the scope can not be passed through the esophagus due to trauma or esophageal strictures.

Supplies needed include: Endoscope, endoscopic grabbers, Pezzer catheter, 14 gauge needle or catheter, 1-2 lengths of #2 suture material ~ 3 feet long, catheter guide, sterile lubricant and luer slip catheter plug.

For percunateous endoscopic gastrostomy (PEG) tube placement, the patient is anesthetized, placed in right lateral recumbency. The right flank is clipped and surgically prepped from 1-2 inches above the last caudal rib to 2-3 inches beyond the last caudal rib. The area should be 4-6 inches in diameter. A 20-24 Fr Pezzer catheter is used for placement; these are available singly and as kits. The endoscope in advanced into the stomach and used to insufflate air into it. This helps to ensure that the spleen or omentum does not become entrapped between the stomach and body wall. An assistant digitally palpates the external body wall ~1-2 cm behind the 9th rib, the palpation can be seen internally and can be used to confirm correct placement of the feeding tube. When the site is confirmed, a 14 gauge needle or catheter is introduced into the stomach through the body wall, a length of #2 suture is threaded through the needle into the stomach and grasped with endoscopic grabbers, the string and scope are removed from the stomach. Ensure that the assistant maintains a hold on their end of the suture and that it doesn't get pulled thorough as the scope is removed. The catheter guide is slid onto the suture and used to secure the Pezzer catheter (it helps to bevel the end of the Pezzer catheter to help it fit into the catheter guide. Using the 14 gauge needle push it through the Pezzer catheter than thread the suture through the needle, remove the needle and secure the suture. Pull everything taunt, apply the sterile lubricant to the feeding tube liberally and using firm and steady pressure pull the catheter guide with Pezzer catheter attached through the body wall, it may be necessary to use a scalpel blade to enlarge the hole in the body wall to allow passage of the tube assembly. It is important to maintain firm and steady pressure throughout the entire passage of the feeding tube from the mouth through the body wall. Once the tube is through the body wall, pull the mushroom tip firmly against the stomach wall, in most animals this can be felt from the outside. An external tube assemble should be made to prevent the tube from migrating back into the stomach, be sure to leave a little extra room (~1 inch) to allow tube movement and weight gain. Place the luer plug into the catheter.

A minimum of 12 hours is needed for a temporary stoma to form before feeding can begin, the feeding tube should be left in place for a minimum of 7-10 days to allow a permanent stoma to form before removal. The tubes can be left in long term (1-6 months) without replacement, when replaced with another PEG tube, low profile silicone tube or foley type feeding tube, the stoma can be used for the rest of the patients' life. Complications associated with PEG tubes include those seen from tube placement such as splenic laceration, gastric hemorrhage and pneumoperitoneum. Delayed complications can also be seen such as vomiting, aspiration pneumonia, tube removal, tube migration, and peritonitis and stoma infection.

Blind percutaneous gastrostomy tube placement involves basically the same technique as endoscopic placement, but a large plastic or steel tube is used instead of the endoscope and a firm wire is used instead of the suture. The catheter is the same as in the endoscopic insertion technique. Reported complications are the same as for PEG tubes, though the risk of splenic, stomach or omental laceration is greater. Contraindications to using the blind technique include severe obesity that would make palpation of the end of the tube difficult and esophageal disease.

Surgical placement has been largely superseded by endoscopic placement because of the ease and speed of placement, lower cost and decreased morbidity. A surgical approach may be indicated in obese animals, those with esophageal disease or when laporatomy is already scheduled. To place a surgical gastrostomy a larger incision is needed into the stomach and the exit location is sometimes hard to locate because of the position on the surgical table. Surgical placement involves placing purse string sutures around the catheter to secure it as well as attaching the stomach to the body wall.

Gastrostomy tube placement is the technique of choice of long-term enteral support. These tubes are well tolerated by the patient, produce minimal discomfort, allow feeding of either gruel recovery diets of blenderized commercial foods, and can be easily managed by owners at home. Patients are able to eat normally with gastrostomy tubes in placed and can easily be used as a nutritional supplement until the patient is totally self feeding. For patients that are difficult to medicate and require long-term medications, many medicines can also be given thought the feeding tube. Gastrostomy tubes can also be used for rehydration therapy as with renal failure. It is typically less stressful for clients to administer fluids through a feeding tube as opposed to under the skin or intravenously. An additional benefit to this use is that regular tap water can be used, further reducing the cost to the clients. The major disadvantage of gastrostomy tubes is the need for general anesthesia and the risk of peritonitis.

For animals requiring long term management, the initial Pezzer catheter can be replaced with either low-profile silicone tubes or with foley type gastrostomy tubes. Both of these types can be placed through the external stoma site without the endoscope. Sedation or anesthesia may be necessary based on the individual patient.

For removal, if the tube has been in place 16 weeks or less the tube may be simply removed. This is best accomplished by placing the patient in right lateral recumbency. The tube is grasped with the right hand close to the body wall, with the left hand holding the animal. Pull firmly and consistently to the right in an upward motion. Some force may be required for this. It is also helpful to ensure that patient has been fasted, and placing a towel over the tube site to catch any gastric contents that may be removed along with the feeding tube. If the tube has been in longer than 16 weeks, the incidence of tube breakage is much higher. Depending on where the breakage occurs as to whether they need to be endoscopically retrieved. Most larger patients can easily pass retained parts, smaller patients may need to have them retrieved.

Alternately, tubes may also be endoscopically removed, but again this would require anesthesia. The feeding tube is cut off at the level of the skin and pushed into the stomach from the outside. Using the endoscopic grabbers, the remaining parts are grabbed and removed through the esophagus.

The exit site is cleaned well with soap and water and dried. Antibiotic ointment may be applied to the site, with the primary purpose to stop the flow of gastric contents out of the hole rather than protect form an infection. The exit hole is allowed to heal by second intension. A light bandage may be applied for the first 12 hours or however long the animal will allow.

Jejunostomy tube placement

Jejunostomy feeding is indicated when the upper gastrointestinal tract must be rested or when pancreatic stimulation must be decreased. Jejunal tubes can be placed either surgically or threaded through a gastrostomy tube for transpyloric placement. Standard gastojejunal tubes designed for humans are unreliable in dogs due to frequent reflux of the jejunal portion of the tube back into the stomach. Investigation is ongoing involving endoscopic placement of transpyloric jejunal tubes through PEG tubes. This technique requires skill and patience to be successful in animals.

Supplies needed for placement include: 5-8 Fr PVC tubing, suture, luer slip catheter plug.

Due to the small diameter of these tubes and the location, liquid enteral diets are recommended. Because the jejunum has minimal storage capacity compared to the stomach, continuous rate infusion using a syringe pump is the preferred method of delivery.

Common complications include osmotic diarrhea and vomiting. It is recommended that the jejunal tube be left in place for 7-10 days to allow adhesions to form around the tube site and prevent leakage back into the abdomen. Completely changing the delivery equipment every 24 hours will help prevent bacterial growth within the system. Clogging is a common problem; a syringe pump may help to decrease the incidence as will flushing well every 4 hours.

When removing, the tube may be simply pulled out after the sutures are removed. The exit hole is allowed to heal by second intension. A light bandage may be applied for the first 12 hours.

Summary

The enteral route is the preferred method of nutritional support in patients with functional gastrointestinal tracts. Many tube and food choices are available and can be tailored to fit the individual patient and condition. Don't let ignorance or fear prevent you from providing your patients with nutritional support, appropriate nutrition should not be treated as an after thought.

Providing our patients with nutritional support should not be treated as an after thought.

References

Willard M. The GI System In: Nelson RW, Couto CG Essentials of Small Animal Internal Medicine. Mosby, St Louis 1992 pp: 305-309

Marks SL. Enteral and Parenteral Nutritional Support In : Ettinger SJ, Feldman EC Textbook of Veterinary Internal Medicine Volume 1, 5th Edition. WB Saunders, Philadelphia 2000 pp: 275-282

Assisted Feeding Techniques In: Hand MS, Thatcher CD, Remillard RL, Roudebush P Small Animal Clinical Nutrition, 4th Edition. Mark Morris Institute , Topeka 2000 pp: 1145-1153

Nutritional Management of Gastrointestinal Disease In: Guilford WG, Center SA, Strombeck DR et al Strombeck's Small Animal Gastroenterology, 3rd Edition. WB Saunders, Philadelphia 1996 pp: 904-908