In a post‑tracheostomy patient who failed a T‑piece trial with bradycardia and dyspnea, does 'pressure support' refer to the ventilator mode, the inspiratory pressure level, or PEEP, and how should it be set?

Understanding "Pressure Support" in Post-Tracheostomy Weaning

In the context of a post-tracheostomy patient who failed a T-piece trial, "pressure support" refers to the inspiratory pressure level (measured in cm H₂O) that augments each spontaneous breath—not the ventilator mode itself or PEEP. 1, 2

Terminology Clarification

Pressure support (PS) is the incremental inspiratory pressure delivered above the baseline expiratory pressure (PEEP/EPAP) during each patient-triggered breath. 3 In bi-level ventilation systems commonly used for weaning, this is calculated as:

• PS = IPAP − EPAP 3
• IPAP (inspiratory positive airway pressure) is the absolute peak pressure during inspiration 3
• EPAP (expiratory positive airway pressure) is the baseline pressure during expiration 3

For example, if IPAP is set to 15 cm H₂O and EPAP to 5 cm H₂O, the pressure support is 10 cm H₂O. 3

Why This Patient Failed T-Piece and What to Do

Patients who develop bradycardia and dyspnea during T-piece trials are experiencing excessive cardiovascular and respiratory muscle stress that pressure support ventilation specifically addresses. 2, 4

Immediate Management Algorithm

Step 1: Resume pressure support ventilation immediately

• Set inspiratory pressure support at 5–8 cm H₂O above PEEP 1, 2
• Maintain PEEP at 5 cm H₂O 2
• Keep tracheostomy cuff inflated at 20–30 cm H₂O 2

Step 2: Stabilize for 24–72 hours

• Address reversible causes: fluid overload (often >20 L in ventilatory failure), cardiac dysfunction, secretion management 2
• Maintain stable pressure support settings during this phase 2

Step 3: Progressive pressure reduction

• Reduce pressure support by 2 cm H₂O every 24–48 hours (not daily T-piece trials) 2
• Monitor for signs of intolerance: tachypnea >30/min, accessory muscle use, oxygen desaturation, hemodynamic instability 2

Step 4: Final spontaneous breathing trial

• Conduct 30-minute trial on low-level pressure support (5–8 cm H₂O), not T-piece 1, 2
• For high-risk patients (previous failure, prolonged ventilation >14 days, cardiac dysfunction), extend trial to 60–120 minutes 2

Why Pressure Support Is Superior to T-Piece for This Patient

Pressure support ventilation reduces inspiratory muscle work by 30–50% compared to T-piece breathing, preventing the cardiovascular decompensation (bradycardia) and respiratory distress (dyspnea) that occurred during the failed trial. 5, 4

Clinical evidence demonstrates that spontaneous breathing trials conducted with pressure support (5–8 cm H₂O) have significantly higher success rates (84.6%) compared to T-piece trials (76.7%), with better extubation outcomes (75.4% vs 68.9%). 2

Specific Pressure Support Settings

Initial settings for difficult-to-wean patients:

• Inspiratory pressure support: 8–10 cm H₂O 2, 4
• PEEP: 5 cm H₂O 2
• Backup respiratory rate: 8–12 breaths/min (spontaneous-timed mode) 3

Target physiological endpoints:

• Respiratory rate <30 breaths/min 4
• Tidal volume >4 mL/kg (ideally 6–8 mL/kg) 4
• No accessory muscle use 2
• Heart rate stable without bradycardia 2

Critical Pitfalls to Avoid

Do not repeat T-piece trials in patients who exhibit cardiovascular instability (bradycardia, dyspnea) during such trials, as they impose excessive respiratory load and hemodynamic stress that can worsen the patient's condition. 2

Do not deflate the tracheostomy cuff until the patient tolerates pressure support ventilation without additional support and demonstrates low risk for aspiration, as maintaining an inflated cuff during weaning reduces aerosol generation and maintains a closed-circuit system. 2

Avoid same-day repeat spontaneous breathing trials after failure, as this depletes respiratory muscle reserves and increases risk of respiratory muscle fatigue, ventilator-associated pneumonia, and mortality (10–20% higher than successful extubation). 2

Role of PEEP in This Context

PEEP (5 cm H₂O) is maintained throughout weaning to:

• Counteract intrinsic PEEP in patients with obstructive lung disease 6
• Maintain alveolar recruitment 6
• Reduce work of breathing by offsetting auto-PEEP 6
• Flush exhaled CO₂ from the circuit (minimum 3 cm H₂O required) 6, 3

PEEP is not the "pressure support"—it is the baseline expiratory pressure upon which inspiratory pressure support is added. 6, 3