Nasogastric and Orogastric Tubes

OVERVIEW

• nasogastric or orogastric tube

USES

• enteral feeding
• administration of drugs, contrast media or activated charcoal
• aspiration of stomach contents to decompress the stomach of fluid, air, or blood
  — reducing the risk of vomiting or aspiration (e.g. gastroparesis, bowel obstruction or ileus)
  — improve ventilation post-intubation in small children (e.g. incomplete drowning)
• sometimes used to instill air into the stomach to detect a gastric perforation on erect CXR
• detection of upper GI haemorrhage (poor sensitivity and specificity)

CONTRAINDICATIONS

• Caustic ingestion or oesophageal strictures (risk of perforation)
• Coagulopathy (epistaxis risk)
• Base of skull fracture
• Severe mid-face trauma (risk of cribriform plate disruption with NGT entering the brain!)

Consider an orogastric tube placement if coagulopathy or facial trauma

DESCRIPTION

Salem sump (see photo of example here)

• double lumen with an air vent (blue side port) which allows atmospheric air to enter the patient’s stomach so that the tube can move freely
• side holes near rounded tip
• radio-opaque line
• funnel connector (to join to a suction or drainage system) and spigot (to cap)
• made of polyvinyl chloride
• some tubes can be aspirated actively with suction created from a wall source or sucking back the plunger on a syringe (tapered Toomey syringe)
• sizes range from 6–18F (e.g. adult 14-18F, child 10-14F)

Fine bore (see photo of example here)

• single lumen
• uses a radio-opaque guidewire to stiffen for insertion
• made of polyurethane (softens at body temperature for comfort)
• cannot be aspirated
• sizes (e.g. 6–8F)
• can remain in situ for longer (weeks)
• may have a radiopaque marker on the tip

METHOD OF INSERTION

Length of insertion

• estimated by measuring from the patient’s nose to ear then down to the xiphoid cartilage

Awake patients

• sit patient upright
• consider nebulised lignocaine, vasoconstrictor spray and lignocaine gel if time (there usually is time!)
• ensure the tube is well lubricated with KY or lignocaine gel
• the tube is advanced and directed horizontally and medially along the floor of the nose and down into the posterior pharynx (“noses go back, they don’t go up!”)
• assist insertion by asking the patient to swallow, or have the patient drink water
• withdraw the tube promptly into the oropharynx if the patient has excessive choking, gagging, coughing, a change in voice, or the appearance of condensation on the inner aspect of the tube

Unconscious patients

• blind approach: fingers in pharynx if neuromuscular blockade, flex neck, manipulate the mandible, larynx and/or cricoid anteriorly
• laryngoscopic guidance and use Magill forceps to feed tube into esophagus

Trouble-shooting insertion

• the most common sites of resistance at the laryngeal level are the arytenoid cartilages and piriform sinus
• Do not attempt to re-use a NGT that has already used for a failed insertion
• Use a fresh tube from the fridge (the colder the better), as these are more rigid and less pliable, and are therefore easier to pass
• If the tube continually curls up in the pharynx, flex the patient’s neck as much as possible and re-insert, which may change the angle sufficiently to pass an obstruction
• Try placing patient’s head in the lateral position or applying lateral neck pressure (may help prevent impaction of the tube on the arytenoids and in the piriform fossa)

If unable to place NGT in an unconscious patient, consider these options

• Use Magill forceps and a direct or video laryngoscope
• Use ETT with a slit in the lesser curvature as guide (can consider using a bougie to place the ETT in the esophagus, not essential and may be traumatic)
• Use soft well lubricated nasopharyngeal airway (NPA)
• Anterior manipulation of laryngeal cartilage
• NGT insertion with angiocath wire to stiffen the tube
• Fibreoptic scope placement using guidewire (i.e. call the cavalry)

CONFIRMATION OF TUBE PLACEMENT

Key methods

• aspiration of gastric contents
  — inspect and check for pH <5 with pH indicator paper
  — limited utility in patients receiving stress ulcer prophylaxis
• capnography or colorimetric capnometry in mechanically ventilated adult patients
  — very useful: pooled  +LR 129.62 and -LR 0.05
• chest/ upper abdominal x-ray
  — ensure all distal openings are below the gastro-esophageal junction
  — used as the de facto gold standard

Other methods

•  aspirating gastric contents and measuring the pH, bilirubin, pepsin, and trypsin levels
• examining the visual characteristics of aspirate (unreliable)
• placing the proximal end of the tube under water and observing for bubbles in synchrony with expiration
• measuring the carbon dioxide level at the proximal end of the nasogastric/orogastric tube (capnography)
• auscultation for a gurgling sound over the epigastrium or left upper quadrant of the abdomen following insufflation of air (unreliable)
  — suspect an esophageal location if the patient immediately burps upon insufflation
• ultrasound
  — high PPV, poor NPV; better for weighted tip NGTs
• spring gauge manometry (in non-mechanically ventilated patients)
• magnetic detection devices
• fluoroscopy
• palpation by surgeon if performed intraoperatively

In adults, tube placement errors vary from 1.3-50% (depending on the study)!

COMPLICATIONS

Insertion

• discomfort!
• malposition (e.g. curling in the mouth or nose, endotracheal and endobronchial placement)
• epistaxsis
• vomiting and aspiration
• placement into the anterior cranial fossa (i.e. base of skull fracture or cranial floor surgery)
• oesophageal variceal hemorrhage (if varices present)
• oesophageal or posterior pharyngeal perforation

During use

• sinusitis
• reflux and aspiration
• pressure areas at site of being secured
• unplanned dislodgement or migration
• blockage, kinking and knotting (can even knot around epiglottis and cause respiratory distress!)

Removal

• mucosal adherence and trauma
• failure (e.g. kinking and knotting)
• dislodgement of endotracheal tube (e.g. if NGT is knotted around)

OTHER INFORMATION

Maximising patient comfort

• NGT insertion is extremely unpleasant in an awake patient, and often under-estimated (Singer et al, 1999)
• Ameliorate the pain and gagging associated with tube placement by using vasoconstrictors (e.g. 0.05% oxymetolazine spray), topical anesthetics, (e.g. lignocaine spray, lignocaine gel) and antiemetics — use these if time permits
• Nebulised lignocaine (4 mL of 10%) can be administered prior to insertion of the tube to reduce discomfort and increase patient compliance (Cullen et al, 2004)
• if necessary consider procedural sedation with ketamine

Blocked tubes

• Unblocking tubes by injecting carbonated beverages (soft drinks) is controversial
• Never aspirate via blue air inlet of Salem Sump
  — Clear air inlet of any fluid by injection 10mls of air into blue air inlet especially if difficulty encountered when aspirating, 10mls of air can be injected down the blue air inlet

Other considerations

• consider orogastric tubes in an intubated patient as it avoids risks such as nasal bleeding and sinusitis
• caution with insertion needed if patients have had gastric bypass surgery or upper GI surgery
• various methods are used to secure tubes (avoid pressure areas around the nares)
• gastric tube insertion can facilitate ventilation post-intubation in small children with gastric distention

References and Links

LITFL

• CCC — Nasogastric Tube versus PEG versus Jejunostomy

Journal articles

• Bong CL, Macachor JD, Hwang NC. Insertion of the nasogastric tube made easy. Anesthesiology. 2004 Jul;101(1):266. PubMed PMID: 15220819. [Free Full Text]
• Cullen L, Taylor D, Taylor S, Chu K. Nebulized lidocaine decreases the discomfort of nasogastric tube insertion: a randomized, double-blind trial. Ann Emerg Med. 2004 Aug;44(2):131-7. PubMed PMID: 15278085.
• Joanna Briggs Institute. Methods for determining the correct nasogastric tube placement after insertion in adults. Best Practice: evidence-based information sheets for health professionals. 2010; 14(1):1-4 [Free Full Text PDF]
• Kirtania J, Ghose T, Garai D, Ray S. Esophageal guidewire-assisted nasogastric tube insertion in anesthetized and intubated patients: a prospective randomized controlled study. Anesth Analg. 2012 Feb;114(2):343-8. PMID: 22104075.
• Mahajan R, Gupta R, Sharma A. Role of neck flexion in facilitating nasogastric tube insertion. Anesthesiology. 2005 Aug;103(2):446-7. PMID: 16052133.
• Singer AJ, Richman PB, Kowalska A, Thode HC Jr. Comparison of patient and practitioner assessments of pain from commonly performed emergency department procedures. Ann Emerg Med. 1999 Jun;33(6):652-8. PMID: 10339680.
• Stayner JL, Bhatnagar A, McGinn AN, Fang JC. Feeding tube placement: errors and complications. Nutr Clin Pract. 2012 Dec;27(6):738-48. PMID: 23064019.
• Tucker A, Lewis J. Procedures in practice. Passing a nasogastric tube. Br Med J. 1980 Oct 25;281(6248):1128-9. PMC1714574.

FOAM and web resources

• Radiopaedia.org — Gastric tube cases (search results)
• Resus.ME — Best way to insert NG tube in intubated patients (2009)