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Procedural Skills (SLO6)
This was previously featured in an exam
You are asked to insert a nasogastric tube for feeding. The chest x-ray to confirm nasogastric tube placement is shown. What is the most appropropriate action?
Answer:
This patient has a NGT that has passed down the trachea rather than the oesophagus. The NGT has then deflected into the left main bronchus before being pushed through lung parenchyma and the visceral pleura into the pleural space. The mantra for inserting NGTs is definitely not "... just keep pushing". The result of this insertion is a left sided pneumothorax. This is supported by the deep sulcus sign that can be seen at the left lung base. To confirm an NG tube is positioned safely, all of the following criteria should be met:- The chest X-ray viewing field should include the upper oesophagus and extend to below the diaphragm.
- The NG tube should remain in the midline down to the level of the diaphragm.
- The NG tube should bisect the carina.
- The tip of the NG tube should be clearly visible and below the left hemidiaphragm.
- The tip of the NG tube should be approximately 10 cm beyond the GOJ (i.e. within the stomach).
Nasogastric Tube Placement
Procedural Skills (SLO6)
Last Updated: 31st January 2023
Indications
- Feeding purposes
- In people who are malnourished or at risk of malnutrition, and have inadequate or unsafe oral intake and a functional, accessible gastrointestinal tract e.g. stroke, coma, pre- or post- gastrointestinal surgery
- Medication delivery
- NG tubes can also be used to deliver certain medications directly into the stomach of patients with the same stipulations as feeding
- Removal of gastric content
- Initial and continued gastric decompression in the intubated patient
- Symptom relief and bowel rest in bowel obstruction
- Aspiration of toxic material
- Diagnostic uses
- Assessment of the presence of or volume of upper gastrointestinal bleeding
- Administration of radiographic contrast
Contraindications
Healthcare professionals will have varying levels of experience in placing nasogastric tubes therefore some contraindications are relative. Advice should be sought and consideration should be made of the following, which is not an exhaustive list:
- Basal skull fractures
- Unstable cervical spinal injuries
- Nasal/pharyngeal /oesophageal obstruction or ulceration
- Choanal atresia
- Tracheoesophageal fistula
- Oesophageal/pharyngeal pouch
- Oesophageal stricture or other abnormalities of the oesophagus
- Oesophageal tumours or have undergone oesophageal surgery
- Oropharyngeal tumours or have undergone oropharyngeal surgery
- Post laryngectomy
- Actively bleeding oesophageal or gastric varices
- Gastric outflow obstruction
- Intestinal obstruction
- Clotting disorders
Complications
The patient should be fully assessed to identify any history of previous nasal fractures, surgery, polyps or other blockages which may complicate nasogastric tube insertion.
Potential complications which may arise during the insertion procedure include:
- Bronchial placement
- Pleural space placement
- Intracranial insertion
- Gastro-oesophageal junction placement of the tip
- Nasal trauma
- Pharyngeal or oesophageal pouch perforation
- Precipitation of variceal bleeding
Procedure
- Position the patient sitting upright with their head in a neutral position
- Estimate how far the NG tube will need to be inserted by measuring from the bridge of the nose to the ear lobe and then down to 5 cm below the xiphisternum
- If available, a local anaesthetic should be sprayed towards the back of the patient’s throat
- Lubricate the tip of the NG tube, insert the NG tube through one of the patient’s nostrils and advance posteriorly along the floor of the nose to the nasopharynx
- Gently advance the NG tube through the nasopharynx; if resistance is met, rotating the NG tube can aid insertion
- Intermittently inspect the patient’s mouth to ensure the NG tube isn’t coiling within the oral cavity and if any resistance is felt throughout passage of tube, do not force the tube
- Continue to advance the NG tube down the oesophagus, you can ask the patient to take some sips of water (if safe) and then swallow as this can facilitate the advancement of the NG tube
- Once you reach the desired nasogastric tube insertion length, fix the NG tube to the nose with a dressing
- Throughout passage of the nasogastric tube the patient should be observed for signs of distress, coughing, cyanosis, gasping etc - any of these may indicate malposition of tube and the tube should be withdrawn
- Once the NG tube is deemed safe for use, the radiopaque guidewire can be removed
Confirming NGT placement
When inserting an NG tube for feeding and/or administration of medication you need to confirm the safe placement of the tube prior to its use. The incorrect placement of an NG tube can result in life-threatening complications (e.g. aspiration pneumonia).
The position of the nasogastric tube tip must be confirmed prior to use by a competent practitioner and the method of confirmation documented.
Testing pH of NG aspirate
Confirmation of safe NG tube placement can be achieved by testing the pH of NG tube aspirate. Gastric content has a low pH (1.5-3.5) whereas respiratory tract secretions have a much higher pH. This difference makes it possible to confidently confirm the safe placement of an NG tube using pH testing alone if the pH is within a safe range (typically 0 – 5.5). If aspiration is unsuccessful or the pH is too high, the patient will require a chest x-ray. The acceptable pH range for confirming NG tube placement can differ, so always follow local guidance. In addition, some hospitals may require a chest X-ray to confirm the safe placement of all NG tubes, regardless of the NG aspirate results, so always consult local guidelines.
Some limitations of pH testing include:
- Stomach pH can be altered by medications (e.g. proton pump inhibitors)
- Obtaining aspirate from NG tubes can be difficult, particularly when using a fine bore tube
Confirming position using a chest x-ray
To confirm an NG tube is positioned safely, all of the following criteria should be met:
- The chest X-ray viewing field should include the upper oesophagus and extend to below the diaphragm.
- The NG tube should remain in the midline down to the level of the diaphragm.
- The NG tube should bisect the carina.
- The tip of the NG tube should be clearly visible and below the left hemidiaphragm.
- The tip of the NG tube should be approximately 10 cm beyond the GOJ (i.e. within the stomach).
An NG tube can be positioned in the left or right main bronchus but to still appear in the midline (hence why the single criterion of an NG tube appearing in the midline is not satisfactory evidence to confirm safe placement). An NG tube can curl up on itself, meaning the tip is placed higher than it should be which can result in reflux and aspiration of NG tube contents. This demonstrates the importance of confirming you can see the NG tube tip clearly.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
