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ENDOSCOPIC ACCESSES FOR ENTERAL NUTRITION
SUBHASH AGAL
Consultant Gastroenterologist, JR Hospital, Mumbai Central.
Enteral nutrition refers to any manner of feeding that uses the gastrointestinal tract. This may be as simple as designing a specialized diet or provision of a nutritional supplement. Alternatively it may require selection of a feeding based on patient's underlying disease and the route of access. The positive impact of nutritional support on patient morbidity and mortality has been repeatedly demonstrated in the clinical trials. Mc Ardle et al demonstrated comparable improvement in nitrogen balance in patients fed enterally by nasogastric tube, as compared with total parenteral nutrition (TPN), but with a significantly decreased complication rate in areas such as hyperglycaemia, essential fatty acid deficiency and sepsis.[1] The rationale for enteral nutrition is its physiological effect on digestion, absorption and hormone-substrate interactions.[2] Enteral nutrition is far superior than parenteral nutrition in maintaining GI integrity, hormone balance, and nutrient utilization. Levine had shown increased intestinal mucosal growth in rats fed enterally as compared with parenterally, after small bowel resection.[3] This may be secondary to direct intraluminal mechanical contact stimulating the epithelial growth and regeneration. It has also been shown that early enteral refeeding prevents bacterial translocation from GI tract, with resultant sepsis.[4] Similarly a meta-analysis by Moore et al of 8 prospective randomized trials had shown that early post-operative enteral feeding might partly prevent post-operative sepsis.[5]
Enteral nutrition is generally considered to be the provision of liquid formulas for nourishment, orally or by tube. Last quarter of previous century has witnessed an explosion in the development and use of enteral feedings.
Guidelines for enteral nutrition
The indication for use of enteral feedings is inability to consume adequate nutrients by mouth and presence of GI tract that can be safely utilized and has absorptive capacity. Table 1 lists the accepted guidelines for enteral nutrition.
ACCESS ROUTES FOR ENTERAL NUTRITION
1. Oral
2. Nasogastric tube
3. Nasoenteric tubes
-nasoduodenal
-nasojejunal
4. Cervical pharyngostomy
-surgical
-percutaneous(over guidewire)
5. Gastrostomy
-percutaneous endoscopic gastrostomy (PEG)
-fluoroscopic gastrostomy
-laparoscopic gastrostomy
-surgical gastrostomy
6. Jejunostomy
-Percutaneous endoscopic jejunostomy(PEJ)
-Percutaneous endoscopic gastrojejunostomy(PEG-J)
-laparoscopic jejunostomy
-surgical
The detailed discussion of routine nasogastric/nasoenteric tube placements, cervical pharyngostomy and surgical gastrostomy/jejunostomy is outside the purview of this article. The main focus will be on endoscopy-assisted procedures for enteral nutrition.
Routine Clinical settings Normal nutrition status with 2% of required nutrientintake for previous 7-10 days Severe dysphagia Major full thickness burns Massive small bowel resection in combination with TPN Low output enterocutaneous fistulas Clinical settings where usually helpful Major trauma Radiation therapy Mild chemotherapy without protracted vomiting Liver failure Severe renal dysfunction Clinical settings where of limited value Intensive chemotherapy with protracted vomiting Acute enteritis < 10% small bowel remaining Acute pancreatitis Clinical settings of no value Complete intestinal mechanical obstruction Ileus Severe diarrhoea High output external fistulas Shock Prognosis not warranting aggressive nutritional support
Table adapted from (4)
Nasogastric and nasoenteric tube-feeding
For short-term tube-feeding (< 4 weeks) nasogastric, nasoduodenal, or nasojejunal tubes are preferred. Nasogastric tube placement is simplest of them all. Nasoduodenal and nasojejunal tube placements require expert manipulation. Specialized "self-propelling" nasojejunal tubes are now available, passage of which can be fecilitated by use of pharmacologic stimulation of motility by prokinetic agents like intravenous metoclopramide or erythromycin or by mechanical stimulation by gastric insufflation of air. Right lateral decubitus positioning may also help.
Endoscpy-Assisted Nasogastric and Nasoenteric Intubation
These tubes are usually placed without fluoroscopic or endoscopic guidance. However difficult intubation requires fluoroscopic and/or endoscopic guidance. Although more expensive, fluoroscopic or endoscopic tube placements are generally faster. Success of endoscopic nasoduodenal or nasojejunal intubation reaches almost 100% whereas use of fluoroscopy alone can give successful intubation in ~90%.[6] Complications associated with nasogastric/nasoenteric tubes are mentioned in Table 2.
1. Aspiration pneumonia 2. Difficulty with placement 3. Metabolic abnormalities 4. Nasal mucosal ulcerations 5. Otitis media 6. Pharyngitis,sinusitis 7. Pneumothorax 8. Pulmonary intubation 9. Reflux esophagitis 10. Ulceration stricture 11. Tracheo-esophageal fistula 12. Tube obstruction, migration
TECHNIQUE
The gastrostomy tubes are short and wide (upto 32 Fr may be placed endoscopically. Jejunostomy tubes are longer and thinner (typically 7-12 Fr). The tubes may be passed by mouth paraendoscopically or via a channel in the endoscope. For jejunal intubation tube is usually left in the second or third part of duodenum and with passage of time the tube advances into jejunum due to intestinal peristalsis. According to a study by Gutske et al, the optimum tube position to minimize reflux was just beyond the ligament of Treitz.[7]
A) Paraendoscopic technique
A short suture material is attached to the distal end of tube. A grasping forceps is passed through the scope channel. The suture material is caught by the grasping forceps and the latter is withdrawn within the scope channel just proximal to the tip of the scope. Thus the tube is secured paraendoscopically. The endoscope plus tube assembly is then passed into the stomach and the tube is then pushed through the pylorus under direct vision. When the tube in second or third part of duodenum, the thread is released and the endoscope is withdrawn. Alternatively the scope-tube assembly itself is negotiated through the pylorus and the forceps carrying the suture tied to the feeding tube is extended distally under vision. The ligature is then released and endoscope is withdrawn. The proximal end of tube is rerouted through the nose for security and comfort.
Another technique to pass the feeding tube is to use an add-on temporary channel to the endoscope. A polyethelene tube with internal diameter of 3.8 mm and external diameter of 4.7 mm is taped to the side of the paediatric endoscope. This serves as a temporary large channel. The thin feeding tube is preinserted into this large channel. The entire assembly is passed and rest of the procedure is same as described above.
B) Insertion through the scope channel
This technique comprises passing a 7 Fr plastic tube over a guidewire through a large channel therapeutic endoscope. The tube and guidewire are advanced through the pylorus under direct vision. When the tip of the tube is in correct position, the scope is withdrawn while further advancing the tube and guidewire through its channel. Guidewire is then withdrawn and tube is rerouted through the nose.
TUBE-GASTROSTOMY AND ENTEROSTOMY
Patients requiring tube feeding for a longer time (4 weeks) are the candidates for gastrostomy or jejunostomy tubes. The various procedures available have already been mentioned before. Each technique has its own risks and benefits but the endoscopic procedures have made gastrostomies widely available, with fewer major complications and cost compared with surgical procedures.[8]
PERCUTANEOUS ENDOSCOPIC GASTROSTOMY (PEG)
PEG was introduced in 1980s after Gauderer and Ponsky performed the first endoscopic gastrostomy in 1979, utilizing home-made kit with a16 Fr catheter. At present several commercial kits are available in market. Table 3 lists the common indications and contraindications for PEG tube placement. A functional UGI tract and prolonged enteral feeding are essential requirements for PEG placements. Feeding is the primary function of a PEG tube but other accepted indications include gastric decompression and drainage. Placement of surgical jejunostomy and a PEG permit feeding distally in the jejunum with gastric decompression through PEG.
Indications Contraindications Altered level of consciousness Coagulation disorders Dysphagia secondary to oro-pharyngeal cancer Marked oesophageal obstruction Gastric decompression. Massive ascites Neurologic event precluding swallowing Obstruction and pseudo-obstruction Tracheo-oesophageal fistula Peritoneal dialysis
Peritoneal metastases
Poor survival potential
Respiratory distress
Severe obesity
Techniques of PEG
An overnight fasting is required for the procedure. Prophylactic IV antibiotic (cephalosporins) is given prior to the procedure. A recent meta-analysis of several trials has shown that a single IV dose of a broad sprectum antibiotic is effective in reducing the incidence of peristomal infections.[9] General anaesthesia is not required for the procedure.
PEG insertion is done by either of the following 3 techniques. Although there is no clear benefit of one technique over the another, push technique causes less trauma to hypopharynx and oesophagus in the presence of partially obstructed oesophagus.
1. Pull-through technique (Ponsky-Gauderer).
2. Push technique (Sachs Vine).
3. Introducer technique (Russell).
The Pull-through Technique
The steps involved in this technique are mentioned below. An endoscopist and an assistant are required for the procedure.
1) Abdominal wall is prepared and draped.
2) Endoscope is passed and UGI tract is surveyed to rule out gastric outlet obstruction.
3) Stomach is inflated with air so that anterior wall of the stomach juxtaposes anterior abdominal wall.
4) Tip of the endoscope is directed towards anterior abdominal wall for transillumination.
5) The abdominal operator firmly indents the anterior abdominal wall with a finger in the region of maximum transillumination which usually corresponds to an area 4 cm to the left of the midline and 2-4 cm below left costal margin.The indentation on the anterior wall of the stomach is seen by the endoscopist and thus appropriate site for gastrostomy is chosen.
6) Local anaesthetic is infiltrated at the site into skin, subcutaneous tissue, and fascia.
7) A 0.5 cm incision is made at the site and deepened through the subcutaneous fat.
8) Abdominal wall operator pushes the 18 gauge needle catheter through the incision into the stomach under endoscopic vision. Needle is removed leaving the plastic cannula in place.
9) A 150 cm long silk ligature is passed through the cannula into the stomach.
10) Meanwhile endoscopist passes a snare through the scope. The silk ligature is grasped with the snare.
11) Endoscope along with the snare holding the ligature is withdrawn out of patient's mouth.
12) The ligature is tied to the tapered tip of PEG tube.
13) Abdominal operator removes the plastic cannula and applies steady traction on the ligature to pull the PEG tube so that tapered end comes out of anterior abdominal wall and the mushroom tip snugly opposes the anterior gastric wall as seen by endoscope which has been passed for the second time.
14) The tube is anchored at the skin by a plastic bolster.
15) The external tube is then cut to an appropriate length.
Patients can be fed within few hours of PEG insertion. Once the gastrocutaneous fistula matures after several days, a skin level button can replace the protruding tube.
The Simplified Pull Technique
The pull technique described earlier necessitates the second passage of the endoscope inside the patient. The simplified pull technique eliminates this requirement. The procedure is as follows:
1) The endoscope is passed with ligature held paraendoscopically with the help of a grasping forceps within the scope channel.
2) A needle catheter is passed through the anterior abdominal wall into the stomach as described earlier. Needle is removed leaving the cannula in place.
3) A bare wire element of the snare is passed into the stomach through the plastic cannula which acts as its sheath.
4) The ligature is grasped with the snare and pulled out of the anterior abdominal wall.
5) The PEG tube is pulled down through the mouth alongside the scope. With the help of endoscopic vision, the mushroom tip of the tube is appropriately positioned on the anterior gastric wall.
The Push Technique
A soft guidewire is passed through the needle catheter into the stomach lumen. The guide wire is pulled out of patient's mouth using a snare. Tension is applied to both ends of the guide wire while the tapered end of gastrostomy tube is passed over it and pushed down into the stomach till it comes out of anterior wall. The tube is then appropriately positioned so that inner bumper of the tube rests on inner gastric wall.
The Introducer Technique
A split sheath introducer is passed over a J-tipped guide wire inserted into stomach lumen through a needle catheter.The guide wire and introducer are removed and a 14 Fr Foley catheter is fed through the split sheath, which is ultimately peeled away.
Removal of PEG
The internal bumper is snared and retrieved by using endoscope after the external portion of tube is cut. Alternatively it can be done without using endoscope. The external part of tube is cut close to the abdominal wall. A Foley catheter is placed into the fistulous tract pushing the internal bumper into the stomach, which is then expelled in faeces.
Complications of PEG
A review of several large series involving a total of more than 1000 patients suggests that PEG tube placement is associated with mortality in 0.5%, major complications (peristomal leakage with peritonitis, necrotizing fasciitis of the anterior abdominal wall, and gastric haemorrhage) in 1%, and minor complications (minor wound infections, stomal leaks, tube extrusion or migration, aspiration, gastrocolic fistula, ileus, and fever) in 8% of patients.[10]
Early pneumoperitoneum, if asymptomatic, may be disregarded, as some escape of air from stomach around the puncture site is common. However, if it is persistent (over several days), leakage around the tube should be suspected. If the leakage is significant or if peritoneal signs are present, operative repair should be undertaken.
PEJ/PEG-J
The primary indication for PEG or PEG-J is for long term feeding when the patient has significant gastro-oesophageal reflux. Jejunostomy tube can be placed under endoscopic guidance through an established gastrostomy tract after removing the gastrostomy tube. The jejunal tube is fed through the gastrostomy tract or tube into the stomach. The tube is caught in a snare passed through the endoscope and it is then advanced across the pylorus along with the scope into the second or third part of duodenum. The endoscope is withdrawn taking care not to dislodge the tube.
Special commercial kits are now available which can be used for de novo feeding jejunostomy at the time of original PEG puncture. The design of the tube is such that distal (jejunal) end of jejunostomy tube protrudes through the mushroom tip of gastrostomy tube. Initial procedure involved is same as in PEG. After seating the gastrostomy tube correctly, the rest of the feeding tube which is lying in oesophagus at this point of time, is brought down the oesophagus endoscopically using grasping forceps. The distal tip (jejunal end) of the tube is then advanced into second or third part of duodenum along with the endoscope while still holding it with grasping forceps. A short ligature at the jejunal end of the tube serves as a handle for the grasping forceps.
Complications of PEJ/PEG-J are same as those of PEG. Though PEG-J is supposed to reduce gastro-oesophageal reflux and pulmonary aspiration, several studies have found that PEG-Js are associated with higher rate (50-85%) of tube dysfunction,[11,12] and do not eliminate the risk of pulmonary aspiration.[13]
Laparoscopic Insertion of Gastrostomy and Jejunostomy Feeding Tubes[14]
When PEG is contraindicated in situations like oesophageal malignancy, gross obesity (with poor transabdominal transillumination with gastroscope), and ascites, feeding gastrostomy or jejunostomy are performed by open surgery. Recently, techniques have been developed for laparoscopic insertion of gastrostomy and jejunostomy feeding tubes.
During laparoscopy the jejunum is first anchored to the posterior abdominal wall with the help of sutures. The jejunostomy tube is inserted using the Seldinger technique and using a standard introducer and peel-away sheath kit. A needle is introduced percutaneously into the jejunum and a guidewire is then passed through the needle. The tract is dilated over the guidewire with a 12 Fr dilator and sheath. The dilator is removed and a 10 Fr catheter is inserted through the sheath. The sheath is then peeled away leaving the feeding tube in the jejunum. The tube feeding can be started in the immediate post-operative period.
The technique for gastrostomy insertion is essentially identical except that a larger(18 Fr) balloon-tipped catheter is used.
Delivery methods of enteral nutrition
1. Bolus method.
2. Gravity method.
3. Pump system.
Bolus feeding is preferred for intragastric feedings in patients who are active and alert. This method frees the patient from any constant feeding device. It can be associated with nausea, diarrhoea, cramps and increased risk of GE reflux with aspiration.
Gravity feedings are delivered via an intermittent or continuous drip. Intermittent gravity feedings are the preferred modality for intragastric feeding.
Pump feeding requires a mechanical device and can be delivered via intermittent or continuous feeding. Continuous pump feedings are preferred for intra jejunal delivery of nutrients.
Complications of tube feeding
Enteral nutrition is often cited as safer than parenteral nutrition. The latter is limited by associated severe infections, metabolic and central venous catheter-associated complications. Table 4 shows the complications related to tube feeding and enteral nutrition.
Mechanical Occluded tube Tube displacement Improper tube placement Wound infection with percutaneous tube placement Nasotracheal irritation or ulceration with nasoenterictube placement Gastrointestinal Abdominal cramping Constipation Diarrhoea Gastro-oesophageal reflux and aspiration Nausea or vomiting High faecal impaction Metabolic Dyselectrolytaemia Dehydration Essential fatty acid deficiency Hypercapnia Hyperglycaemia Vitamin or trace element deficiencies
REFERENCES
1. Mc Ardle AH, Palmason C, Morency I, Brown RA. A rationale for enteral feeding as the preferable route for hyperalimentation. Surgery 1981; 4 : 616-623.
2. Koruda MJ, Guenter PG, Rombeau JL. Enteral nutrition in the critically ill. Crit Care Clin 1987; 3 : 133-153.
3. Levine GM, Deren JJ, Yedizmir E. Small bowel resection: Oral intake is the stimulus for hyperplasia. Am J Dig Dis 1976; 212 : 542-546.
4. ASPEN Board of Directors. Guidelines for the use of enteral nutrition in the adult patient. JPEN 1987; 11 : 435-439.
5. Moore FA, Feliciano DF, Andrassy JR, et al. Early enteral feeding compared with parenteral, reduces postoperative septic complications: the result of a meta-analysis. Ann Surg 1991; 216 : 172-183.
6. Ott DJ, Mattox HE, Gelfard DW, et al. Enteral feeding tubes placement by using fluoroscopy and endoscopy. Am J Roentgenol 1991; 157 : 769-771.
7. Gutske RF, Varma RR ,Soergel KH. Gastric reflux during perfusion of the small bowel. Gastroenterology 1970; 59 : 890-895.
8.Stern JS. Comparision of percutaneous endoscopic gastrostomy at a community hospital. Am J Gastroenterol 1986; 81 : 1171-1173.
9.Sharma VK, Howden CW. Meta-analysis of randomized ,controlled trials of antibiotic prophylaxis before percutaneous endoscopic gastrostomy. Am J Gastroenterol 2000; 95 : 3133.
10. Klein S, Heare BR, Soloway RD. The " buried bumper" syndrome: A complication of percutaneous endoscopic gastrostomy. Am J Gastroenterol 1990; 85 : 448.
11. Simon T, Fink AS. Recent experience with percutaneous endoscopic gastrostomy/jejunostomy (PEG/J) for enteral nutrition. Surg Endosc 2000; 14 : 436.
12.Hoffer EK ,Cosgrove JM, Levin DQ, et al. Radiologic Gastrojejunostomy and percutaneous endoscopic gastrostomy: A prospective, randomized comparision. J Vasc Interv radiol 1999; 10 : 413.
13.Wolfsen HC, Kozarek RA, Ball TJ, et al. Tube dysfunction following percutaneous endoscopic gastrostomy and jejunostomy. Gastrointest Endosc 1990; 36 : 261.
14.L. Michael Brunt, Nathaniel J Soper. Laparoscopic surgery. In Maingot's Abdominal Operations, 10 th edition, MJ Zinner (ed); 269.
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