Proper Method to Cap a Tracheostomy Tube
Before capping a tracheostomy tube, you must deflate the cuff completely or use a cuffless tube to allow air passage through the vocal cords for phonation and breathing. 1
Prerequisites for Capping
The patient must meet these criteria before attempting to cap:
- Medical and respiratory stability established
- Weaned from mechanical ventilation or requiring only nocturnal support
- Tracheostomy tube size should not exceed two-thirds of the tracheal lumen (unless fenestrated) 2
- Patent upper airway confirmed above the tracheostomy
- Adequate secretion management with thin secretions that are easy to suction 2
- Ability to vocalize with the tracheostomy occluded 2
Stepwise Capping Protocol
Step 1: Speaking Valve Trial First
Start with a one-way speaking valve before attempting full capping. 3 This allows gradual acclimatization to laryngeal airflow and changes in hypopharyngeal pressure. The speaking valve must be used with a deflated cuff to redirect airflow upward through the vocal cords during expiration 1.
Step 2: Cuff Deflation
When the patient tolerates the speaking valve during wakefulness and is considered low-risk for requiring mechanical ventilation, deflate the cuff completely 1. The cuff must be deflated to allow passage of air through the vocal cords for phonation 1.
Critical Safety Point: Complete cuff deflation is essential. Partially deflated cuffs with atmospheric pressure can cause tracheal pressure drops up to 4.2 kPa, while completely deflated cuffs reduce this to 3.4 kPa maximum 4. Incomplete deflation increases airway resistance and may cause unsuccessful capping trials 4.
Step 3: Safety Checks Before Capping
Before placing the cap, verify:
- Suction catheter passes easily through the tube into the trachea to confirm patency 5
- Cuff is completely deflated (not just at atmospheric pressure) 4
- Above-cuff secretions ≤1 mL per hour 6
- Patient alert (eyes open to voice minimum) 6
- Cough strength at least moderate 6
Step 4: Apply the Cap
Once the speaking valve is well-tolerated and the above criteria are met, proceed to capping the tracheostomy tube 3. The cap occludes the external opening, forcing all airflow through the upper airway.
Step 5: Monitoring During Capping Trial
Observe for signs of respiratory distress:
- Increased work of breathing
- Oxygen desaturation
- Tachypnea (respiratory rate >18 breaths/min suggests intolerance) 7
- Inability to maintain minute ventilation <10 L/min 7
If respiratory distress develops, immediately remove the cap and reassess 7.
Common Pitfalls to Avoid
Never cap with an inflated cuff. This completely obstructs the airway and will cause immediate respiratory failure 1. The cuff creates a closed-circuit system that prevents air passage to the upper airway.
Do not use supplemental oxygen via the tracheostomy tube side port during capping with a standard one-way valve. This can generate dangerously high pressures (84-148 cmH₂O) during airway obstruction 8.
Avoid vigorous hand ventilation attempts if the tube is displaced, as this causes significant surgical emphysema and worsens access 5.
Do not proceed with capping if the patient cannot tolerate a speaking valve. Valve intolerance indicates potential airway obstruction and requires investigation before advancing to capping 3.
Troubleshooting Failed Capping Trials
If the patient fails capping despite meeting criteria:
- Consider tracheostomy tube downsizing 3, 9. Smaller tubes reduce airway pressures significantly and improve success rates 9.
- Perform formal airway evaluation (bronchoscopy or laryngoscopy) to identify obstruction 7
- Assess for tracheal stenosis using the tube occlusion protocol—patients who develop respiratory distress during capping often have clinically important tracheal obstruction 7
- Consider polysomnography with capped tracheostomy for unclear causes of failed trials 3
Special Considerations
For patients transitioning from invasive to noninvasive ventilation, polysomnography with a capped tracheostomy is recommended to assess readiness 3. This provides objective data on gas exchange and sleep-disordered breathing when pharyngeal muscle tone is maximally decreased 3.
The screening criteria of medical stability, respiratory stability, and above-cuff secretions ≤1 mL/hour provide 100% specificity, 95% sensitivity, and 100% positive predictive value for successful cuff deflation 6.