Enteral Feeding Devices
World Small Animal Veterinary Association World Congress Proceedings, 2007
David Miller, BVSc, MMedVet(Med)
Ridgemall Veterinary Specialist Referral Centre, Johannesburg, South Africa

The documented benefits of early enteral nutritional support of hospitalized human patients and experimental animal models include:

 supplying the energy needed for recovery and healing

 maintenance of intestinal structure and function

 decreased mucosal permeability to bacteria and endotoxins

 preservation of secretary immunoglobulin-A [IgA] concentrations.

 Maintaining protein levels [esp. albumin].

Despite these benefits, we routinely ignore or delay the nutritional needs of sick animals, perhaps because the translation of these findings into practical applications is often difficult and owing to the intense focus on life-threatening medical and surgical problems.

The goal of this talk on nutritional support is to provide a formula for techniques that can be used by the attending personnel with maximum efficiency and ease. [Partial and total parenteral nutrition will not be handled in this talk].

Commercial pet food diets are recommended for nutritional support because these diets do not need to be supplemented with protein micronutrients and can be fed through these tubes. Commercial human enteral formulas are too low in protein for dogs and definitely to low in protein for cats!

Who Needs a Tube?

Nutritional support should be considered in patients demonstrating recent weight loss exceeding 10% or in patients in whom oral intake has been or will be interrupted for more than 2 days. We should feed any cat that presents with anorexia as the presenting complaint or any critically ill patient that is not eating for more than a day or non critical patients anorexic for more than 1-3 days post trauma or surgery.

How to Place a Naso-Oesophageal Tube

Naso-oesophageal tubes are used for short-term nutritional support of most anorectic hospitalized patients that have a normal nasal cavity, pharynx, oesophagus, and stomach. We will often naso-oesophageal feed animals as a "food bridge" until they eat or until they are strong enough for a GA for corrective surgery. Naso-oesophageal tube feeding is contraindicated in animals that are persistently vomiting, comatose or lack a gag reflex.

This is our first line of feeding in

 Anorectic cats that do not need a GA [bite wounds, icterus, anaemia, collapse etc]

 Puppies with parvo-virosis or any severe gastro

 Dogs that need feeding, including dogs or cats post surgery that are anorectic

 length of tube to be inserted into the patient is determined by measuring the distance from the tip of the nose to the fifth intercostal space. This helps verify the correct placement of the tube in the oesophagus NOT the stomach. Tube placement too near to the cardia of the stomach also increases the risk of persistent vomiting.

 No sedation needed just local anaesthetic in the nose. Four or five drops of lidocaine are recommended. Do not exceed 4 mg/kg of lignocaine in the cat it may cause haemolysis.

 The tip of the tube should be lubricated with a water-soluble lubricant.

In cats, the tube is passed by maintaining the animal's head at the normal angle and directing the tip of the tube in a ventro-medial direction [aim for the medial canthus of the opposite eye]. The tube should move with minimal resistance through the ventral meatus and nasopharynx and into the oesophagus. An 8 French gauge catheter can almost always be passed in cats over 3 kg.

In dogs, the presence of a small ventral ridge at the start of the nasal passage stops one just passing a tube into the nose. The ridge necessitates directing the tip of the tube straight (to allow passage over this ventral ridge) and then the tube is directed in a ventro-medial direction at the same time as pushing the tip of the nose upwards with your thumb. This maneuver opens the ventral meatus.

If the tube cannot be passed with minimal resistance into the oropharynx, it should be withdrawn and redirected because it could be positioned in the middle meatus with its tip encountering the ethmoid turbinate.

 Once the tube has been passed to the correct level, it should be secured as close to the nostril as possible with either suture material or glue. An Elizabethan collar is required for most dogs and some cats to prevent the inadvertent removal of the tube.

Tube position in oesophagus must be checked:

Dog, by injecting 3 to 7 ml of water through the tube and observing for a cough response. Negative pressure with a 10-20 ml syringe will produce air if the tube is in the trachea and a vacuum if it is in the oesophagus.

Cats, correct tube placement is confirmed by means of a lateral thoracic radiograph to determine the position of the radio-opaque tube in the esophagus (NB cats do not cough if water is instilled into the trachea).

How to Place an Oesophagostomy Tube

Tube placement can be done in under 5 minutes. Oesophagostomy tubes are indicated for patients requiring longer-term nutritional support and/or bypass of the oral cavity or oropharynx or for patients that will be fed at home or for anorexic animals that will be under GA anyway so a tube is placed for ease of feeding. The only major complication that has been associated with oesophagostomy tube placement is wound infection at the ostomy site where the tube exits the skin.

 Use local anesthesia in the back of throat to reduce depth of GA needed

 The left neck region is clipped for tube placement.

 Pre-measure/mark the tube from the proposed stoma site to the 5th intercostal space.

 Place a curved forceps through the mouth so that it causes a skin bulge in the middle of the neck.

 A skin stoma is cut longitudinally over the forceps and then the forceps is forced through the oesophagus and connective tissue and out of the skin stoma by blunt dissection.

 The end of the catheter is then grasped by the haemostat and pulled through the stoma, via the oesophagus and out of the mouth.

 The tube is then redirected and fed into the oesophagus well past the level that you marked earlier.

 Pull the tube out of the skin stoma so the loop in the mouth is pulled into the oesophagus. As the kink unravels, the tube will obviously give at that moment that the kink is removed from the tube.

 Pull the tube out to your mark.

 Close the stoma with a tobacco pouch suture

 Fix the tube in place by means of a Chinese finger suture that is anchored to the periosteum of the atlas.

 Radiograph the chest to confirm the position is not too deep or the tube kinked.

 Use anti-septic on the stoma wound and loosely bandage the neck

How to Place Gastrostomy tubes

Gastrostomy tube feeding is indicated for long-term (weeks to months) nutritional support of anorectic or dysphagic animals. Gastrostomy feeding tubes are of comparatively large diameter allowing the economic use of blended pet foods and the direct administration of medication. Gastrostomy tube feeding is contraindicated in animals with persistent vomiting, decreased consciousness and gastrointestinal obstruction.

Percutaneous Endoscopic Gastrostomy Technique

The animal is placed in right lateral recumbency and surgically preparing the skin caudal to the left coastal arch. The endoscope is introduced into the stomach, and the stomach is inflated until the abdomen is distended but not drum tight. An appropriate site for insertion of the tube is determined by endoscopically monitored digital palpation of the abdominal wall. A small incision is made in the skin with a scalpel blade and an intravenous catheter is pushed through the body wall into the lumen of the stomach. Nylon suture is threaded through the catheter into the lumen of the stomach. The suture is grasped with forceps then withdrawn out of the mouth. The suture material is passed through a sharp tipped pipette and secured to the feeding tube. Gentle traction is applied to the suture material at its point of exit form the abdominal wall. The feeding tube is pulled through the oesophagus and the pipette facilitates its passage through the body wall, allowing the stoppered end of the catheter to draw the stomach wall against the body wall. The feeding tube is anchored in this position by an external bumper placed over the catheter at the skin surface.

Blind Percutaneous Gastrostomy Technique

A gastrostomy tube placement device can be prepared with a length of stainless steel tubing. The length of the tubing is determined by measuring the distance from the nasal planum to the iliac crest and adding 15cm. The outer diameter of the tube ranges from 1.2cm (patients weighing < 10kg) to 2.5cm for dogs weighing more than 20kg. The distal tip of a stainless steel tube can be flared and deflected 45 degrees to the long axis of the tube to help displace the lateral body wall. The lubricated tube is passed through the mouth and into the stomach so the end of the tube displaces the stomach and lateral abdominal wall. A skin nick is made over the end of the tube and a 14-guage catheter advanced into the lumen of the tube. A guide wire prepared [guitar string] is attached to suture material that is 60 cm longer than the stomach tube. The guide wire is threaded through the catheter, into the tube, and out the mouth. The attached suture is pulled through the tube. The tube and catheter are removed, and the suture is attached to a gastrostomy tube, which is secured in an identical fashion to PEG tube procedure.

Surgical Tube Gastrostomy Technique

A surgical approach is indicated in obese patients, in patients with esophageal pathology or obstruction, and in patients that require laparotomy for reasons other than tube placement. Surgical tube gastrostomy can be performed via either a routine midline laparotomy or left paracostal flank approach 1 to 2 cm caudal to the last rib. The use of a mushroom-tipped catheter is recommended because the self-retaining tip is more resistant to acid damage than the balloon-tipped urethral catheters. A 3- to 5-cm skin incision is made just caudal and parallel to the last rib, beginning 2 to 4 cm below the ventral edge of the epaxial muscles. Blunt dissection is used to separate the muscles in the direction of their fibers, and the peritoneum is incised. The greater curvature of the stomach is located digitally and retracted toward the incision. Location of the stomach can be facilitated by having an assistant inflate the stomach with air using an orogastric tube.

The stomach is examined to identify the left lateral aspect of the gastric body or the caudal aspect of the fundus for the ostomy site. The stay sutures are placed in the seromuscular layers at the 12-o' clock and 6-o' clock positions. Two full-thickness purse-string sutures are placed around the selected ostomy site. A stab incision is made in the middle of the purse string, and the feeding tube is introduced into the stomach. The purse-string sutures are tightened and tied, starting with the inner suture. A layer of omentum is placed around the ostomy site between the stomach and the body wall to help prevent leakage of gastric contents. The stomach is then sutured to the body using 2-0 nylon sutures placed around the ostomy site. The tube may exit through the initial grid incision or via a separate stab incision. Securing of the tube outside the stomach is the same as for the PEG tube procedure.

Gastrostomy Tube Removal

For percutaneously placed tubes, it is recommended that the tube be left in place for a minimum of 7 to 10 days. The tube can be cut at the body wall and the mushroom tip pushed into the stomach to be passed in the feces. This method is safe in mid- to large-size dogs. Alternatively, a stylet can be inserted into the tube to flatten the mushroom tip, while exerting firm traction on the tube. The gastrocutaneous fistula should seal with minimal or no leakage within 24 hours.

Speaker Information
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Dave Miller, BVSc, MMeDVet [Med]
Ridgemall Specialist Referral Centre
Johannesburg, South Africa

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