32: Gastric and Transpyloric Intubation

In gastric intubation, a gastric tube is inserted through the nose (NG) or mouth (OG) to the stomach. In transpyloric intubation, a transpyloric tube is inserted through the nose or mouth through the pylorus into the duodenum or jejunum.

1. Enteric feeding in the following situations:

   1. High respiratory rate. Enteric feedings are used at some centers if the respiratory rate is >60 breaths/min to decrease the risk of aspiration pneumonia (controversial).

   2. Neurologic disease. If it impairs the sucking reflex or the infant's ability to feed. An abnormal gag reflex is an indication for a gastric tube.

   3. Premature infants. May have immature sucking and swallow mechanisms that normally develop after 32 weeks. Preemies have immaturity of motor function and tire before they can take in enough calories to maintain growth.

   4. Insufficient oral intake.

2. Gastric decompression. In infants with necrotizing enterocolitis (NEC), bowel obstruction, or ileus.

3. Administration of medications.

4. When a transpyloric tube is placed, a gastric tube is needed to empty gastric contents and administer medications.

5. Analysis of gastric contents.

Infant feeding tube (3.5 or 5F if <1000 g or 5–8F if ≥1000 g), for decompression dual-lumen vented Replogle tube (6, 8, 10F) (Note: tubes come with and without stylets), stethoscope, sterile water (to lubricate the tube), syringes (10–20 mL), 1/2-inch adhesive tape, benzoin, gloves, suctioning equipment, cardiac monitor, stethoscope, pH paper, and bag-and-mask ventilation with 100% oxygen (in case of emergency). Recommended: colorimetric device (eg, CO2nfirm Now CO₂ detector [Covidian, Mansfield, MA] or capnograph) to help confirm the position of the tube by absence of CO₂ within the tube.

1. Monitor heart rate and respiratory function throughout the procedure. Place the infant in the supine position, with the head of the bed elevated. The infant can be swaddled to provide comfort.

2. There are 4 methods of estimating gastric tube insertion length:

   1. OG tube insertion. Table 32–1 provides OG guidelines for very low birthweight infants <1500 g.

   2. Age-related/height-based (ARHB) method

      1. Less than 1 month of age: NG only

         1. NG tube insertion length (cm) = 1.950 cm + 0.372 × (infant's length in centimeters)

      2. Greater than 1 month of age (if greater than 44.5 cm in length)

         1. OG tube insertion distance = 13.3 cm + 0.19 × (infant's length in centimeters)

         2. NG tube insertion distance =14.8 cm + 0.19 × (infant's length in centimeters)

   3. NEMU (nose/ear/mid-umbilicus) for NG/OG tubes. Measure the distance from the tip of the nose to the bottom of the ear (earlobe) to the midpoint between the xiphoid and the umbilicus. This measurement proved to be the most accurate in one study.

   4. NEX (nose/ear/xiphoid). Distance from the tip of the nose to the bottom of the ear to the xiphoid (controversial). This technique gave an insertion distance that was too short in infants with a high error rate and is considered inaccurate by some.

3. Mark the length on the tube. Measure based on choice of the preceding calculations and lubricate the tube by moistening the end of the tube with sterile water. (Note that smaller tubes such as 3.5F clog easily).

4. Pain management. Consider nonpharmacologic methods such as oral sucrose, swaddling, or containment by flexing and holding the infant. Make sure appropriate tube lubrication is used.

5. The tube can be placed in 1 of 2 insertion points, oral or nasal. Most units use indwelling technique as opposed to the intermittent intubation.

   1. Many centers preferentially use NG tubes as they do not limit breast or bottle feeds. Do not use nasal insertion with nasal trauma, recent esophageal surgery, choanal atresia, nasal prong continuous positive airway pressure (CPAP), respiratory distress, grunting, with oxygen requirement (CPAP, nasal ventilation, or nasal supplemental oxygen). In these cases, the oral route is preferred.

   2. Oral insertion. Less traumatic and does not impact respiration. It is easier for the infant to dislodge and may limit breast and bottle feeding.

   3. Nasal insertion. Avoid NG in very low birthweight infants <2 kg because of increased incidence of respiratory compromise.

      1. Check nostrils for patency.

      2. Flex the neck, push the nose up, and insert the tube, directing it straight back (toward the occiput).

      3. Tilt head slightly forward. Advance the tube to the desired distance.

   4. Oral insertion. Push the tongue down with a tongue depressor and pass the tube into the oropharynx. Slowly advance the tube the desired distance.

6. Do not push against any resistance (perforation potential). Remove stylet if present.

7. Continue to observe the infant for respiratory distress and/or bradycardia. Stop procedure immediately until the patient is stabilized.

8. Determine the location of the tube and never instill materials into the tube until the position is verified. Radiologic verification can be done and is considered the gold standard and is recommended at the time of initial tube placement or tube change. The radiograph should be read before feeding or medication instillation by an appropriate trained health care provider. Nonradiologic verification can be done by the following methods:

   1. Auscultation is done but is not reliable as the only method to verify placement. Injecting air into the tube with a 10–20 mL syringe and listen for a rush of air (a gurgle in the stomach commonly referred to as the “whoosh test”). This may be unreliable because a rush of air can occur when the tip is in the distal esophagus and respiratory tract air can be heard by auscultation.

   2. Visual inspection of the aspirate has not been reliable when used alone as gastric contents can vary in color. Normal gastric contents can be blood tinged, yellow, pale green, off white, clear, milky, or tannish in color. Small bowel aspirates are usually golden yellow or greenish brown. Respiratory secretions can be yellow, straw colored, clear, or white. Respiratory and gastric aspirates may be similar in color therefore the result may be misinterpreted. If used with pH it may be more beneficial. Grossly bloody aspirate may indicate a perforation.

   3. CO₂ at the proximal end of the tube. Absence of CO₂ suggests placement in the alimentary tract and CO₂ with a normal capnograph tracing suggests placement in the trachea and distal airways. Inadvertent insertion in the trachea and distal airway occurs from 0.3% to 15%.

   4. Gastric aspirate pH testing using pH paper or a pH meter (pH paper is preferred over litmus paper). A pH aspirate <5 suggests gastric placement. If the pH is >6, then the placement should be questioned. The mean values of pH are not usually affected by feeding status or use of acid suppression medications. Note: Swallowed amniotic fluid may transiently raise gastric pH, and some preterm infants have a decreased ability to produce gastric HCl. Gastric pH at birth is high (pH 6–8) because of alkaline amniotic fluid. Gastric fluid has a much lower pH than respiratory or intestinal fluid. To differentiate intestinal and respiratory fluid, pH is less effective because both have a high pH.

   5. Testing aspirate for bilirubin, pepsin, and trypsin can help identify site of tube placement. Usually not practical for routine procedures. Gastric aspirate testing: bilirubin <5, high pepsin, low trypsin. Intestinal aspirate testing: bilirubin >5, low pepsin, high trypsin. Respiratory aspirate: little or no trypsin or pepsin. A bilirubin <5 mg/dL, pepsin ≥100 mcg/mL, and trypsin ≤30 mcg/mL indicates gastric placement.

   6. If the location is still in question, obtain a radiograph. However, this only verifies the location at the exact time of the radiograph. The tube tip should be below T12. See Figure 11–8, which demonstrates a nasogastric tube properly positioned in the stomach.

   7. It is best to verify placement after insertion, once per shift, before each feeding, and with medication administration. Some recommend radiography to verify placement if planning to initiate enteral feeding or administering medication.

9. Aspirate the gastric contents and secure the tube to the cheek with benzoin and 1/2-inch tape. For NG tubes, make certain the tube does not press on the nasal ala. For feeding, attach the tube to a syringe. For decompression, connect the tube (preferably a dual-lumen Replogle tube) to low continuous suction.

10. When not in use, the tube should be left open in a dependent drainage position below the level of the stomach.

Disconnect suction (if attached) and pinch gastric tube closed when pulling it out so contents will not go into the pharynx.

1. Apnea and bradycardia. Usually mediated by a vagal response and resolve without specific treatment.

2. Hypoxia. Always have bag-and-mask ventilation with 100% oxygen available to treat this problem.

3. Misplaced tube. Incorrect placement in trachea, esophagus, Eustachian tube, trachea, or oropharynx. Twisting, coiling, or knotting of the tube.

4. Perforation of the esophagus, posterior pharynx, stomach, or duodenum. The tube should never be forced during insertion

5. Aspiration. If feeding has been initiated in a tube that is accidentally inserted into the lung or if the gastrointestinal tract is not passing the feedings out of the stomach. Periodically check the residual volumes in the stomach to prevent over distention and aspiration. (See Chapter 54.) Any NG or OG tube may increase gastroesophageal reflux and risk of aspiration pneumonia.

6. Nasopharyngeal complications. Irritation, bleeding, infections. Grooved palate with prolonged OG placement.

Transpyloric intubation requires a gastric tube for aspiration, drainage, and medication administration. Cochrane review found that transpyloric tubes are not recommended in premature infants because there was no evidence of any beneficial effect of transpyloric feeding in preterm infants, with increased adverse effects. Feedings with human milk via transpyloric tubes may reduce apnea and bradycardia in preterm infants with suspected gastroesophageal reflux.

1. Enteric feeding in the following conditions:

   1. Not tolerating gastric feeding (eg, severe gastroesophageal reflux)

   2. Infants at risk for aspiration (the transpyloric tube is below the pyloric sphincter)

   3. Delayed gastric emptying

   4. Motility disorders

   5. Severe gastric distension

   6. Plain intolerance of gastric feeds (persistent gastric residuals)

2. To test duodenal and jejunal contents

3. Postoperative duodenal atresia

Weighted infant feeding tube (silastic tubes preferred with or without stylet) 6F <1500 g, 8F >1500 g, stethoscope, sterile water (to lubricate the tube), a syringe (20 mL), 1/2-inch adhesive tape, pH paper, continuous infusion pump and tubing, gloves, suctioning equipment, and bag-and-mask ventilation with 100% oxygen.

1. Determine insertion length. Measure from using the ARHB, NEMU, or NEX method. Add the distance from the designated point to the right lateral costal margin. Mark the point on the tube with tape.

2. Follow initial steps for gastric intubation as noted on Gastric aspirate pH testing using pH paper or a pH meter (pH paper is preferred over litmus paper). Confirm the initial gastric position as previously described.

3. Place infant into a right lateral position. With the patient on his right side, elevate the head of the bed 30–45 degrees.

4. To distend the stomach. Inject 10 mL/kg of air through the tube and then close the tube.

5. Insert the tube to the desired length. Keep the infant in the right side down position for 1–2 hours to allow the weighted tube to migrate into the duodenum.

6. Periodically, inject 2–3 mL air and aspirate the tube. No air (“snap test,” high-pitch crackles and inability to aspirate air) suggests the tube is in position in the duodenum. An alkaline (pH >6) and a bilious (gold to green) aspirate suggests proper placement. (See also Section III.E.5.)

7. Place an OG/NG tube as described on Many centers preferentially use NG tubes as they do not limit breast or bottle feeds for aspiration and medication delivery. Note: Consult PharmD specialist for medications that are administered into the stomach or duodenum.

8. Check placement by checking the pH and color of the aspirate. If pH >6 and the color of the aspirate is golden yellow, the tube is probably in the transpyloric position. To further confirm, check bilirubin level in the aspirate (a value >5 is seen if tube is in transpyloric position).

9. Confirm placement with a radiograph. The tip of the tube should be just beyond the second portion of the duodenum. See Figure 11–9. Aspirate contents or initiate tube feeding.

10. Flushing the tube with 3 mL of water after each use will limit tube obstruction. Avoid flushing tubes with small caliber syringes (1–5 mL) as they generate high pressure and may rupture tubing.

11. If long-term use anticipated, consider changing the tube very 2–4 weeks.

Discontinue the infusion, pinch off the tube, and withdraw slowly. Gastric tube can be left in place or removed as described on Removal of tube.

These are similar to the NG/OG tube placement Aspiration. Other complications may include:

1. Inability to pass tube beyond pylorus. Fluoroscopic guidance may be necessary.

2. Aspiration. Transpyloric feeding tubes do not have a decreased risk of aspiration as compared with gastric feeding tubes.

3. Infection. Local infection or sepsis can occur. Enterocolitis can occur secondary to Staphylococcus or NEC.

4. Malabsorption. Enteral feeds bypass the stomach: fat malabsorption, increased frequency of bowel movements, some medications may not be absorbed.

5. Rare complications. Intussusception, pyloric stenosis, enterocutaneous fistula, methemoglobinemia in very premature from intestinal obstruction and inflammation induced by the transpyloric tube, pyloric stenosis, bronchopleural fistula, and pneumothorax.