Suction Catheter

A suction catheter is a sterile, flexible tube used to clear airway secretions. In ventilated or intubated patients, one end of the catheter passes through the endotracheal or tracheostomy tube and the other connects to a suction canister and vacuum source. By removing mucus and fluids that the patient cannot cough up, suction catheters help maintain airway patency, improve oxygenation, and reduce infection risk. (Oropharyngeal suctioning uses hard Yankauer or soft catheters with large tip openings to clear saliva or vomit.) Suctioning often provokes a strong cough and burning discomfort, so patients are usually pre-oxygenated and sedated or given analgesics when possible.

• Definition: A sterile PVC or rubber tube (French scale), usually 50–55 cm long, inserted into the airway to aspirate secretions.
• Connection: One end connects to the patient’s airway (via oral/nasal route, endotracheal, or tracheostomy tube); the other attaches to a vacuum suction system with collection canister.
• Purpose: Clears bronchial or oropharyngeal secretions when the cough reflex is weak or absent, preventing airway obstruction and aiding ventilation. It also provides samples for lab analysis if needed.

Types and Tube Design

Suction catheters come in open and closed formats. In the open technique, a sterile single-use catheter is inserted through an accessible airway (mouth, nose, or disconnected endotracheal tube) to remove secretions. In contrast, a closed (inline) system encloses a reusable catheter in a sterile sleeve within the ventilator circuit. The closed method allows continuous ventilation and oxygen delivery during suctioning and reduces aerosolization risk.

Other design features include:

• Tip Shape: Yankauer tips (hard plastic) for oropharyngeal use have large/angled openings. Flexible catheters (soft PVC) have a straight or angled “whistle” tip with side holes (e.g. DeLee or Coude tips). (Tips are often color-coded by French size.)
• Catheter Size: Measured in French (Fr) units or diameter. As a rule, the catheter’s outer diameter should not exceed ~50–70% of the internal airway diameter. This prevents complete occlusion and allows some airflow. For example, a 12 Fr catheter (≈4 mm OD) is appropriate for an 8 mm endotracheal tube. Manufacturers often grade catheters (e.g. “10 Fr = 3.3 mm OD” etc.).
• Single vs. Multi-use: Open catheters are usually single-use and sterile. Closed catheters are reusable in-line units changed per protocol. Both types typically have a thumb or finger-controlled valve to intermittently apply suction to the tip.

Indications for Use

Suctioning is performed only for clinical indications, not on a fixed schedule. Indications include:

• Visible or palpable secretions: Wheezes or rhonchi on auscultation, noisy breathing, or secretions in the artificial airway.
• Mechanical ventilation issues: Rising peak airway pressures, ventilator alarms (e.g. occlusion), or sawtooth patterns on flow-volume loops.
• Respiratory distress signs: Sudden oxygen desaturation, increased respiratory rate/coughing, suspected aspiration of vomit or fluid.
• Preventive measures: In comatose or intubated patients who cannot cough, routine oropharyngeal suction can prevent pneumonia (though normal saline instillation is generally not recommended).

Always assess the patient before suctioning: ensure the procedure is necessary, explain it to the patient, and position the head to optimize drainage (e.g. lateral or semi-Fowler’s position).

Equipment and Preparation

Before suctioning, assemble equipment and take precautions:

• Personal protective equipment (PPE): Wear gloves, gown, eye protection/mask, and cap as indicated. Suctioning can aerosolize pathogens.
• Sterile supplies: For open suction, use a sterile catheter, sterile gloves and lubricant (if needed). Closed systems require a new sterile sleeve per policy.
• Vacuum setup: Check the suction machine and tubing. Test suction on sterile water: cover catheter tip (or submerge in water) and confirm vacuum, listen for noise of suction. Ensure tubing is intact, not kinked or blocked.
• Suction pressure: Set appropriate negative pressure. Guidelines suggest <150–200 mmHg in adults and lower pressures in children (e.g. 100–120 mmHg for children, 70–100 mmHg for neonates); some protocols aim for −80 to −120 in most patients. Use the lowest effective suction to minimize trauma.
• Catheter selection: Choose the largest bacteriologically appropriate size that is still ≤50–70% of airway diameter. Many clinicians memorize example pairings (e.g. 8 Fr for small child, 12 Fr for adult).
• Patient preparation: Pre-oxygenate with 100% O₂ for 30–60 seconds (via bag or ventilator). Ensure continuous ECG or pulse ox monitoring. If time allows, give analgesic/sedative as ordered to reduce pain and reflexes.

Suction Technique (Step-by-Step)

1. Pre-suction checks: Confirm indication, explain procedure, monitor baseline vitals. Position patient (neck slightly extended for orotracheal, neutral for nasotracheal).
2. Measure insertion depth: Estimate how far to insert the catheter. For ET/trach suction, measure to the carina level (often the distance from mouth to xiphoid minus a few cm) or use the marking at the tip of the endotracheal tube. In general, do not advance catheter much past the end of the artificial airway.
3. Insert catheter (no suction): With sterile gloves, gently insert the lubricated catheter into the tube or airway (or thru the closed-suction port) without applying suction. Advance it until you meet slight resistance or at the preset depth. In awake patients, insertion will induce coughing. Never apply suction while advancing, as this can traumatize mucosa.
4. Apply suction on withdrawal: Close the thumb valve and slowly withdraw the catheter while applying suction. Rotate or oscillate the tip to clear secretions uniformly. Suctioning should be intermittent (apply as you pull back 1–2 cm at a time).
5. Limit duration: Each pass should last no more than 10–15 seconds (often 5–10 sec for children). Prolonged suctioning greatly risks hypoxemia. If needed, pause and re-oxygenate between passes.
6. Flush catheter: After pulling the catheter out, irrigate it into the collection container with saline (if using water trap) to clear retained secretions.
7. Repeat if necessary: If airway secretions are still copious, wait 30–60 seconds (on 100% O₂) before a second pass, watching vital signs. Do not exceed 2–3 passes per session.
8. Post-suction care: Reassess the patient – check breath sounds, SpO₂, and comfort. Continue monitoring until stable. Discard disposable equipment and perform hand hygiene.

Open vs. Closed Technique: In open suctioning, the patient is temporarily disconnected from the ventilator. This allows catheter access but interrupts ventilation. In closed (in-line) suctioning, a sterile catheter is advanced through a special adapter in the circuit. Closed suction preserves PEEP and oxygenation and reduces aerosol spread, which is advantageous in patients with high FiO₂/PEEP needs or contagious infections. Both techniques should follow sterile technique for the catheter to prevent infection.

Key Tips and Best Practices

• Catheter Sizing and Occlusion: Always ensure the catheter allows some airflow around it. Manufacturers often label catheters by Fr; a quick rule is “2 × (ET tube size in mm) – 2” in Fr as a maximum. Never use a catheter that nearly completely blocks the airway (avoid >70% occlusion).
• Pressure Adjustments: Double-check the vacuum gauge often. Pediatric patients require lower pressures (e.g. −100 mmHg max), while adults may tolerate up to −150 or −200 mmHg). Always use the minimal effective suction. If secretions are very thick or dry, instilling a few mL of saline may loosen them, though routine saline instillation is not recommended.
• Prevent Trauma: Do not force the catheter past obstructions. Never palpate or prod beyond the carina. Use a gentle twisting motion, and withdraw if bleeding or severe coughing occurs. Choose a straight-cut catheter tip for deeper suction (angled cuts are usually for pharyngeal suction).
• Monitor Closely: Continuously observe oxygen saturation and heart rate. Suctioning can cause bradycardia (via vagal stimulation) or tachyarrhythmias. If severe desaturation or arrhythmia occurs, stop and re-oxygenate before proceeding.
• Breath Strategy: Provide 100% O₂ before, between, and after passes. Use the “shallow suction” method (advance 1–2 cm past the tube end) routinely to limit hypoxemia. In ventilated patients, consider pre-oxygenation with a manual resuscitator to further boost O₂. Encourage the patient to take deep breaths if awake, and suction on exhalation if possible.
• Infection Control: Treat the suction catheter as part of the sterile field for open technique. If closed suction, follow the device instructions (usually change sleeve every 24–48 hours). Discard single-use catheters immediately after use. Vigilance prevents nosocomial infections.
• Documentation: Record the procedure specifics (time, patient tolerance, amount/color of secretions, complications). Chart changes in vital signs or ventilator pressures.

Complications and Health Considerations

Suctioning must balance clearing the airway against potential risks. Key complications include:

• Hypoxemia: Removal of oxygen from the lungs and interruption of ventilation can rapidly lower saturation. This is mitigated by pre-oxygenation and limiting suction time.
• Bradycardia and Arrhythmias: Vagal stimulation from tubing contact often causes bradycardia, especially in infants. Hypoxia and stress can trigger tachycardia, ventricular arrhythmias or even cardiac arrest. Continuous ECG monitoring is advised.
• Blood Pressure & IICP Spikes: Suction-induced stress can transiently raise blood pressure and intracranial pressure. Sedation and gentle technique minimize this.
• Mucosal Trauma and Bleeding: Rough insertion or deep suctioning can ulcerate the trachea or bronchial mucosa, causing bleeding. Observe for bloody secretions and use smaller catheter if trauma occurs.
• Bronchospasm: Mechanical irritation may induce bronchoconstriction, especially in reactive airway disease. Pre-treatment with bronchodilators can be considered in asthmatics.
• Infection Risk: Although removing infected secretions, the procedure itself can introduce pathogens or drive secretions deeper. Use sterile technique to minimize cross-contamination.

According to guidelines, thorough suctioning only when indicated (rather than on a schedule) reduces complications and does not harm outcomes. AARC recommendations emphasize preoxygenation, using the shallow technique, keeping passes brief (≤15 sec), and suctioning as needed to keep the airway clear.

Summary for Clinicians

Suction catheters are essential tools in airway management for removing secretions in adults and children. Clinicians should remember: suction only clinically indicated secretions, use appropriate catheter size and suction pressure, and perform the procedure briefly and aseptically. Always preoxygenate, monitor the patient closely, and be prepared to manage hypoxemia or arrhythmias. Proper technique – inserting without suction and then withdrawing with suction and rotation – maximizes clearance while minimizing mucosal injury.

Staying vigilant for complications and documenting each suctioning episode are crucial. For example, evidence-based guidelines now discourage routine saline instillation (to avoid pushing bacteria deeper). By following these best practices – combining sterile technique, limited passes, and careful monitoring – doctors and nurses can safely keep the airway clear and support ventilation.