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PE23.9-11 | Gastrointestinal Procedures — SDL Guide

Learning Objectives

• Perform nasogastric (NG) tube insertion on a manikin following the standard paediatric technique
• Verify correct NG tube placement using aspiration and auscultation methods
• Perform intravenous (IV) cannulation on a model, selecting appropriate sites for paediatric patients
• Describe and demonstrate intraosseous (IO) access technique on a manikin
• Recognise indications, contraindications, and complications of each procedure

INSTRUCTIONS

Vascular access and tube feeding are among the most frequently performed emergency and critical-care procedures in paediatric practice. A child in severe dehydration or cardiac arrest who cannot be accessed intravenously may die within minutes if the clinician cannot secure IO access. Similarly, a malnourished child who cannot self-feed requires correct NG tube placement for life-saving nutritional rehabilitation. Mastery of these three procedural skills — NG tube insertion, IV cannulation, and IO access — is a mandatory competency before you manage acutely ill children unsupervised.

References

• Ghai Essential Pediatrics, 9th Ed, Ch 4 (procedures) (textbook)
• Nelson Textbook of Pediatrics, 21st Ed, Ch 71 (emergency procedures) (textbook)
• PALS (Paediatric Advanced Life Support) guidelines — AHA/IAP (guideline)
• WHO/UNICEF: Management of Severe Acute Malnutrition, 2007 (guideline)

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Version 2.0 | NMC CBUC 2024

Clinical Indications and Relevance

Each of the three procedures serves a distinct but complementary clinical purpose in the spectrum of paediatric care — from scheduled nutritional support to emergency resuscitation. Recognising which procedure is indicated in a given clinical scenario is the first practical skill you must develop, because deploying the wrong tool wastes critical time.

Nasogastric (NG) tube insertion is indicated when a child cannot or should not feed by mouth but the gut is functional. Key indications include: (1) severe acute malnutrition with poor appetite or inability to drink therapeutic feeds; (2) altered consciousness or encephalopathy where aspiration risk prevents oral feeding; (3) postoperative patients before oral intake is established; (4) administration of medications in a child who cannot swallow; and (5) therapeutic suctioning for bowel obstruction or post-surgical ileus. Contraindications to NG insertion include suspected basal skull fracture (use OG route instead), severe facial trauma, oesophageal obstruction, and recent oesophageal surgery.

Intravenous (IV) cannulation is the standard route for all parenteral fluid therapy, blood products, medications, and intravenous nutrition. In a ward or clinic setting, IV access is routinely established in any child requiring parenteral therapy. In emergencies (severe dehydration, septic shock, resuscitation), establishing IV access rapidly is the clinical priority. The challenge in paediatrics is that peripheral veins are small, collapse during circulatory shock, and move — making cannulation technically demanding.

Intraosseous (IO) access provides emergency vascular access when IV access cannot be established rapidly. The marrow cavity of long bones communicates directly with the central venous circulation via emissary veins and can accept any drug or fluid that can be given intravenously. PALS guidelines recommend IO access when 2 IV attempts fail or when 90 seconds have elapsed in cardiac arrest without IV access. IO access should not be delayed out of discomfort — in a child in cardiac arrest or severe shock, it is as effective as central venous access and far faster.

Procedure	Primary indication	Emergency threshold	Key contraindication
NG tube	Unable/unsafe to feed orally	Immediate in severe SAM	Basal skull fracture, oesophageal obstruction
IV cannulation	Parenteral therapy in ward/emergency	First attempt in all emergencies	Local infection at site
IO access	Emergency vascular access	After 2 IV fails or 90 sec in arrest	Fracture at same bone, previous IO at same site <24 h

NG Tube Anatomy: Nasopharyngeal Route and NEX Measurement

Anatomy and Governing Principles

A sound understanding of the relevant anatomy prevents the most common procedural complications and guides the correct technique for each intervention.

NG tube anatomy: The nasopharyngeal route passes from the nares through the inferior turbinate, the nasopharynx (a right-angled turn posteriorly), down the posterior oropharynx, through the upper oesophageal sphincter, along the oesophagus (posterior to the trachea), and through the lower oesophageal sphincter into the stomach. The key anatomical danger is the trachea: if the tube is misdirected anteriorly instead of posteriorly at the nasopharyngeal turn, it enters the trachea and bronchi, causing respiratory distress or pneumothorax. Flexing the neck (chin to chest) during insertion helps direct the tube posteriorly. The correct depth is estimated by the NEX (Nose-Ear-Xiphoid) measurement: the distance from the tip of the nose to the earlobe to the xiphisternum, which approximates the distance from nares to the stomach.

IV cannulation anatomy: In children, the most accessible peripheral veins are the dorsum of the hand (dorsal metacarpal veins), the antecubital fossa (median cubital vein), the dorsum of the foot (dorsal venous arch), the saphenous vein at the medial ankle, and scalp veins in neonates and young infants (frontal, parietal, temporal veins — note that blood flows TOWARD the heart in scalp veins so the needle must be directed proximally as usual). Veins feel like a soft cord under the skin, compressible on pressure. In shock, veins collapse and are harder to palpate — using a tourniquet, warm compresses, or transillumination (in neonates) helps. The governing principle: advance the needle at 10–15° to the skin, feel the 'give' as you enter the lumen, then lower the angle and advance the cannula while withdrawing the needle.

IO access anatomy: The preferred site in children is the proximal tibia, specifically the anteromedial flat surface of the tibia, 1–2 cm below the tibial tuberosity (the bony prominence just below the kneecap). This site is away from the growth plate (epiphyseal plate), which is located at the tibial head superiorly — inserting above the tuberosity risks growth plate injury. The tibial cortex is thin in children (1–2 mm), allowing easy penetration. The medullary cavity connects to the systemic venous circulation; drugs and fluids infused into the marrow pass directly into the systemic circulation with pharmacokinetics similar to central venous administration. Alternative IO sites include the distal femur, distal tibia, and humeral head.

Intraosseous Access Site — Proximal Tibia

Procedure and Technique

Consistent technique across all three procedures reduces complications and builds the procedural memory that allows you to perform under pressure in emergencies. Each procedure below is presented as a numbered step sequence designed for manikin practice; the physical sensations described — the 'give' of IO cortex penetration, the 'flashback' of blood in an IV cannula hub, the sound of air over the epigastrium during NG verification — are the confirmatory cues you must learn to recognise and trust. Practise these steps until they become automatic, because the stressed brain in a real emergency defaults to procedural memory rather than conscious deliberation. The following standard sequences should be practised verbatim on manikins before adapting them to individual patient anatomy under supervision.

Consistent technique across all three procedures reduces complications and builds the procedural memory that allows you to perform under pressure in emergencies. The following stepwise approach is designed for manikin practice and applies directly to supervised clinical practice.

NG tube insertion — step by step:
1. Prepare equipment: NG tube of appropriate size (Fr = age/2 + 12, or refer to age-based chart — a common approximation: Fr 6–8 for infants, Fr 8–10 for toddlers, Fr 10–12 for school-age children), 10 mL syringe, pH paper, hypoallergenic tape, lubricant, gloves.
2. Measure the tube: with the child upright or semi-reclined, measure from the tip of the nose → earlobe → xiphisternum (NEX measurement) and mark this length on the tube with tape.
3. Position the child: for cooperative children, head slightly flexed (chin toward chest — facilitates posterior passage). For infants, have an assistant hold the head in neutral or slight flexion.
4. Lubricate and insert: lubricate the tube tip with water-soluble gel. Insert gently through the more patent nostril, directing the tube straight back (not upward — the floor of the nose is horizontal). When the tube reaches the nasopharynx, ask the child to swallow (or give a sip of water if safe) and advance during swallowing. Advance smoothly to the marked depth.
5. Verify placement: (a) Aspirate gastric contents with a 10 mL syringe — pH should be ≤5 on pH paper. (b) Auscultate over the epigastrium while injecting 5–10 mL of air — a gurgling sound is heard. X-ray is the gold-standard but not required for routine placement if aspiration confirms pH ≤5.
6. Fix the tube: secure with hypoallergenic tape to the nose and cheek. Document the tube size, insertion depth, and verification method.

IV cannulation — step by step:
1. Site and size: choose a vein by inspection and palpation. For most children, the dorsum of the hand is first choice; for critically ill children in shock, antecubital or saphenous access may be larger. Cannula size: 24G for neonates/small infants, 22G for children, 20G for older children and adolescents.
2. Prepare: apply tourniquet 5–7 cm above the site. Clean with chlorhexidine swab, allow to dry. Distract the child (parental presence, play, sucrose in neonates).
3. Insert: hold the skin taut. Insert the cannula at 10–15° to the skin, bevel up. A 'flashback' of blood into the cannula hub confirms entry into the vein. Lower the needle angle to 5°, advance the cannula 1–2 mm further into the lumen, then advance the plastic cannula off the needle while withdrawing the needle.
4. Verify and secure: release the tourniquet. Flush with 0.9% saline — smooth, painless flush with no swelling confirms intravascular placement. Secure with transparent dressing and tape.
5. Document: site, cannula gauge, flush result, date and time.

IO access — step by step:
1. Equipment: EZ-IO drill system (preferred) or Jamshidi manual IO needle; 10 mL syringe; 0.9% saline for flush; local anaesthetic if child is conscious (1% lignocaine 0.5 mL locally over the insertion site).
2. Landmark: identify the tibial tuberosity (bony bump below the kneecap). Move 1–2 cm below and slightly medial onto the flat anteromedial surface of the tibia. This is the insertion point. Flex the knee slightly and stabilise the leg.
3. Insert: hold the EZ-IO drill perpendicular to the bone surface (90°). Drill through the cortex with gentle downward pressure — you will feel a 'give' as the cortex is breached and the needle enters the marrow cavity. A loss of resistance indicates correct placement.
4. Verify: (a) the needle stands upright without support; (b) aspiration of marrow (if possible — not always possible); (c) flush 10 mL of 0.9% saline freely without swelling — if saline infuses easily and there is no extravasation, the needle is correctly placed.
5. Administer: connect IV tubing. All IV drugs and fluids can be administered via IO; manual pressure or an infusion pump may be needed to push fluids through the marrow against resistance.
6. Remove within 24 hours: IO access is temporary — remove as soon as IV access is established (maximum 24 hours) to prevent osteomyelitis.

NG Tube Insertion in a Child — Step-by-Step Procedure