What are the recommended settings for T pause and T insp (inspiratory time) on a Maquet ventilator for an Acute Respiratory Distress Syndrome (ARDS) patient?

T Pause and T Insp Settings for ARDS on Maquet Ventilator

For ARDS patients on a Maquet ventilator, set inspiratory time (T insp) to achieve an I:E ratio of approximately 1:2 to 1:1, typically resulting in T insp of 0.8-1.2 seconds, and use an end-inspiratory pause (T pause) of 0.3-0.5 seconds to measure plateau pressure while ensuring it remains <30 cmH₂O. 1

Inspiratory Time (T Insp) Settings

Target an inspiratory time that allows adequate gas distribution while preventing auto-PEEP:

• Set T insp between 0.8-1.2 seconds for most ARDS patients, adjusting based on respiratory rate and desired I:E ratio 2, 3
• Maintain I:E ratio between 1:2 and 1:1 to allow sufficient expiratory time and prevent air trapping 1, 2
• At a respiratory rate of 20-35 breaths/minute (recommended for ARDS), this typically translates to T insp of approximately 1.0 second 4
• Monitor for intrinsic PEEP development—if intrinsic PEEP ≥1 cmH₂O develops, shorten T insp 5

End-Inspiratory Pause (T Pause) Settings

Use T pause primarily for measuring plateau pressure, not as a continuous ventilation strategy:

• Set T pause at 0.3-0.5 seconds when measuring plateau pressure to ensure accurate readings 1
• Measure plateau pressure regularly (every 4-6 hours minimum) to confirm it remains <30 cmH₂O 1
• Prolonging EIP to 0.7 seconds can reduce dead space ventilation and PaCO₂, but this should only be done if I:E ratio remains ≤1:1 and no intrinsic PEEP develops 5
• Do not routinely use prolonged inspiratory pauses as a ventilation strategy—the primary benefit is for pressure measurement, not gas exchange improvement in standard practice 5

Core Ventilator Settings Framework for ARDS

These settings must be maintained regardless of T pause/T insp adjustments:

• Tidal volume: 6 mL/kg predicted body weight (range 4-8 mL/kg PBW) 1, 3
• Plateau pressure: <30 cmH₂O (strong recommendation) 1, 3
• PEEP: Higher PEEP (typically 10-15 cmH₂O) for moderate-to-severe ARDS 1, 2, 3
• Respiratory rate: 20-35 breaths/minute to maintain minute ventilation 4
• FiO₂: Titrate to SpO₂ 88-95% 2, 3, 4

Practical Algorithm for Adjusting T Insp and T Pause

Follow this sequence when setting up or adjusting these parameters:

1. Start with standard settings: T insp = 1.0 second, T pause = 0.3 seconds for plateau pressure measurement 2, 4

2. Check plateau pressure: Perform inspiratory hold maneuver with 0.3-0.5 second pause 1

   • If plateau pressure >30 cmH₂O: Decrease tidal volume first (down to 4 mL/kg if needed) 1, 3
   • If still elevated: Consider adjusting PEEP or implementing rescue therapies 3

3. Assess for auto-PEEP: Check end-expiratory hold

   • If intrinsic PEEP ≥1 cmH₂O: Shorten T insp or decrease respiratory rate 5
   • Ensure I:E ratio does not exceed 1:1 1, 5

4. Monitor gas exchange:

   • If PaCO₂ elevated and pH >7.20: Accept permissive hypercapnia 3, 4
   • If PaCO₂ problematic: Consider prolonging EIP to 0.7 seconds (only if no auto-PEEP and I:E ≤1:1) 5

Critical Pitfalls to Avoid

Common errors that worsen outcomes:

• Never prioritize normalizing PaCO₂ over lung-protective ventilation—accept permissive hypercapnia with pH >7.20 3, 4
• Do not use prolonged inspiratory pauses routinely—they are primarily for pressure measurement, not a standard ventilation strategy 5
• Avoid I:E ratios >1:1—this causes air trapping and hemodynamic compromise 1, 5
• Do not increase tidal volume to improve ventilation—maintain 4-8 mL/kg PBW even with hypercapnia 1
• Monitor for auto-PEEP development—prolonged inspiratory times can cause intrinsic PEEP ≥1 cmH₂O, which worsens hemodynamics 5

Evidence Regarding Prolonged Inspiratory Pause

Research shows that prolonging EIP to 0.7 seconds can decrease dead space ventilation (Vd/Vt from 0.70 to 0.64) and reduce PaCO₂, allowing for tidal volume reduction while maintaining the same PaCO₂ 5. This resulted in decreased plateau pressure (24 to 22 cmH₂O) and driving pressure (13.4 to 10.9 cmH₂O) 5. However, this approach should only be used selectively when hypercapnia is problematic and standard lung-protective ventilation parameters are already optimized 5.