Enteral Feeding, Nasogastric Tube Insertion & Urinary Catheterization

Enteral access and urinary catheterization represent foundational bedside procedures in medical-surgical and critical care nursing. Mastering their anatomical indications, insertion protocols, verification tests, and infection prevention bundles is essential to safeguarding patient airway patency, gastrointestinal integrity, and renal tract health.

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1. Nasogastric (NG) Tube Insertion, Care & Verification

A nasogastric tube is a flexible conduit passed through the nares, through the pharynx, and down the esophagus into the stomach cavity.

Types of Nasogastric and Enteral Tubes

• Levin Tube: A single-lumen, flexible plastic or rubber catheter (typically 14 to 18 French in adults) with terminal drainage holes. Used for diagnostic gastric washing, short-term medication instillation, or intermittent drainage. Continuous high suction is contraindicated with single-lumen tubes because negative vacuum draws the gastric mucosa into the drainage eyelets, causing mucosal erosion and hemorrhage.
• Salem Sump Tube: A double-lumen, radiopaque clear plastic tube. The larger primary lumen connects to suction for continuous or intermittent decompression. The smaller secondary lumen terminates in an external blue pigtail air vent. The air vent continuously draws ambient atmospheric air into the stomach, preventing the suction eyelets from adhering to the delicate gastric mucosa.
  • Critical Nursing Rule: The blue pigtail air vent must NEVER be clamped, tied off, connected to suction, or flushed with enteral formula. If gastric contents reflux out through the blue vent, flush the air lumen with 10 to 20 mL of air (never saline or water) to re-establish the air cushion, or insert an approved antireflux valve.
• Sengstaken-Blakemore Tube: A specialized triple-lumen tube utilized as an emergency intervention to arrest life-threatening hemorrhage from bleeding esophageal varices. Incorporates a gastric balloon (inflated with 200–250 mL air to compress the gastroesophageal junction), an esophageal balloon (inflated to 20–45 mmHg to compress esophageal varices), and a gastric aspiration lumen.
  • Emergency Safety Mandate: A pair of scissors must be taped conspicuously to the head of the bed at all times. If the patient experiences acute respiratory distress, cyanosis, or stridor (signaling upward migration of the balloon into the oropharynx, occluding the trachea), the nurse must immediately cut across all three lumens with scissors to instantly deflate both balloons and extract the tube to prevent fatal asphyxiation.
• Small-Bore Enteral Feeding Tubes (Dobhoff / Keofeed, 8–12 Fr): Narrow, highly flexible polyurethane tubes with a weighted tungsten tip and internal guidewire (stylet). Designed specifically for long-term enteral nutrition. Once removed following radiographic placement confirmation, the internal metal stylet must NEVER be reinserted while the tube remains in the patient due to catastrophic risk of esophageal or bronchial perforation.

Clinical Indications & Contraindications

• Indications: Gastric decompression (paralytic ileus, small bowel obstruction, intractable post-anesthetic vomiting), enteral nutritional support in dysphagic patients, gastric lavage in acute chemical or drug poisonings, and diagnostic analysis of gastric contents.
• Contraindications: Severe midface or maxillofacial trauma, basilar skull fracture (fracture of the cribriform plate permits inadvertent intracranial passage into brain parenchyma; an orogastric tube must be placed under fluoroscopic guidance instead), recent esophageal anastomosis, esophageal stricture, or severe coagulopathy.

NEX Measurement & Insertion Protocol

1. Position the client in High Fowler's position (90°) with the spine straight and head aligned.
2. Assess nares for septal deviation, obstruction, and airflow patency; select the more patent nostril.
3. NEX Measurement: Measure the tube length from the tip of the Nose to the Earlobe, and then down to the Xiphoid process of the sternum. Mark the measured distance with waterproof tape or note the centimeter gradation (typically 50 to 55 cm in an average adult).
4. Lubricate the distal 2 to 4 inches (5 to 10 cm) of the tube generously with water-soluble lubricant (e.g., K-Y Jelly). NEVER use petroleum jelly or oil-based lubricants, as inadvertent aspiration into the lungs produces irreversible lipid pneumonia.
5. Gently insert the tube along the floor of the nasal cavity toward the ear, maintaining a straight horizontal plane (not directed upward into the nasal turbinates).
6. When the tube reaches the nasopharynx (client may gag), pause briefly. Instruct the client to flex the neck forward (tucking chin to chest closes the epiglottis over the glottic aperture, directing the tube into the esophagus) and swallow sips of water through a straw.
7. Advance the tube smoothly in tandem with each swallow until the predetermined NEX mark reaches the naris.
8. Immediate Abort Signs: If the patient develops coughing, cyanosis, stridor, gasping, or inability to vocalize, STOP IMMEDIATELY and withdraw the tube into the posterior pharynx; these signs indicate tracheal entry.

Placement Verification Standards

Enteral Tube Feeding Nursing Rules

• Gastric Residual Volume (GRV): Measure GRV prior to each intermittent bolus feeding or every 4 to 6 hours during continuous infusions. If GRV exceeds 250 mL on two consecutive measurements or > 500 mL on a single measurement (or institutional policy threshold), return the aspirated volume to the stomach to avoid metabolic alkalosis and severe electrolyte loss, withhold the feeding, and notify the physician.
• Aspiration Prevention: Maintain the head of the bed elevated at 30° to 45° (semi-Fowler's to Fowler's) throughout feeding and for at least 30 to 60 minutes after feeding completion.
• Flushing Protocol: Flush the tube with 30 mL of water before and after each feeding, every 4 hours during continuous feeding, and before and after medication administration (using 15 mL flushes between individual crushed medications).

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2. Urinary Catheterization: Sizing, Insertion & CAUTI Prevention

Urinary catheterization involves introducing a sterile catheter through the urethra into the urinary bladder.

Types of Urinary Catheters

• Straight / Intermittent (Robinson) Catheter: A single-lumen flexible catheter used to drain the bladder once (e.g., relieving acute urinary retention, assessing post-void residual, collecting a sterile diagnostic specimen) and withdrawn immediately after bladder evacuation.
• Indwelling Retention (Foley) Catheter: A double-lumen catheter designed for prolonged drainage. One lumen drains urine continuously into a sterile drainage collection bag; the second lumen terminates in an inflatable retention balloon that anchors the catheter inside the bladder neck.
• Three-Way Foley Catheter: Contains three separate lumens: urine drainage, retention balloon inflation, and continuous bladder irrigation (CBI). Indicated following Transurethral Resection of the Prostate (TURP) or open prostatectomy/bladder resection to irrigate the surgical bed continuously with sterile normal saline, washing away blood clots and preventing urinary outflow obstruction.
• Coudé Catheter: Characterized by a curved, tapered, semi-rigid tip designed specifically to navigate past enlarged prostatic lobes in men with Benign Prostatic Hyperplasia (BPH) or tortuous urethral strictures. The raised locator bump on the drainage funnel indicates the upward orientation of the curved tip.

Sizing and Balloon Inflation Principles

• The French (Fr) Scale: Measures external catheter diameter: 1 French unit = 1/3 mm (0.33 mm).
  • Adult Females: 12 to 14 Fr.
  • Adult Males: 14 to 16 Fr (longer shaft, typically 40 cm vs. 22 cm for females).
  • Pediatric Patients: 8 to 10 Fr.
  • Continuous Bladder Irrigation (TURP): 18 to 22 Fr (large-bore lumen to prevent clot occlusion).
• Retention Balloon Inflation: Retention balloons are designed to accommodate 5 to 10 mL of fluid. Always inflate the balloon exclusively with STERILE WATER (typically 10 mL sterile water into a 5 mL balloon to ensure symmetrical distension).
  • CRITICAL DANGER: NEVER inflate the balloon with normal saline (crystallization of sodium chloride over time deposits microcrystals inside the narrow inflation channel, occluding the valve and preventing balloon deflation upon removal) or air (causes the balloon to float, kinking the catheter tip and obstructing the drainage eyelets).

Sterile Insertion Technique: Female vs. Male Protocols

CAUTI (Catheter-Associated Urinary Tract Infection) Prevention Bundle

Catheter-associated urinary tract infections represent one of the most common hospital-acquired infections globally. Clinical practice enforces an evidence-based prevention bundle:

1. Aseptic Technique: Maintain strict surgical asepsis during insertion using sterile gloves, drapes, and single-use prepackaged sterile catheter kits.
2. Closed Drainage Circuit: Maintain an uninterrupted closed drainage system. Never disconnect the junction between the catheter and drainage tubing unless executing continuous closed bladder irrigation under sterile orders.
3. Bag Positioning: Maintain the urine drainage bag continuously below the level of the patient's bladder at all times to eliminate gravitational retrograde backflow of contaminated urine into the bladder. Never suspend the collection bag from the bed side rails (elevating rails lifts the bag above bladder level); anchor to the rigid bed frame.
4. Tubing Stabilization: Secure the catheter to the patient using a dedicated stabilization device (StatLock) to the upper thigh in females or upper thigh / lower abdomen in males to eliminate mechanical traction, frictional urethral trauma, and meatal erosion.
5. Hygienic Emptying: Empty the collection bag regularly using a dedicated, clean measuring container for each patient. Never permit the drainage spigot to touch the container rim. Wipe the spigot with an alcohol prep pad after reclosing.
6. Prompt Removal: Assess continued clinical necessity daily. The single most effective strategy to eradicate CAUTI risk is the earliest possible removal of the catheter (within 24–48 hours postoperatively).