Ventilator Settings Presentation Order
When presenting ventilator settings, mention Pressure Support (PS) first, followed by PEEP/EPAP. This convention reflects the hierarchical importance of these parameters in determining tidal volume and patient comfort, with PS being the primary driver of ventilation and PEEP serving as an adjunctive support mechanism.
Rationale for PS-First Convention
The pressure support level is the primary determinant of tidal volume delivery and represents the active inspiratory assistance provided to the patient 1. In clinical practice and published guidelines, PS is consistently referenced before PEEP when describing bi-level ventilation settings 1.
Clinical Examples from Guidelines
- Bi-level ventilation settings are described as "IPAP/EPAP" or "PS/PEEP" format, with the inspiratory pressure always listed first 1
- When adjusting ventilator parameters, guidelines recommend "increasing pressure support by 2-5 cmH₂O" as the primary intervention before optimizing PEEP 2
- Standard notation follows the pattern: "pressure setting of 20 cm H₂O" mentioned before discussing EPAP levels 1
Physiologic Justification
Pressure support determines the primary ventilatory work, generating tidal volume and reducing respiratory effort 2, 3. PEEP serves a secondary but critical role by counterbalancing intrinsic PEEP and reducing the inspiratory threshold load required to trigger breaths 3, 4.
Hierarchical Function
- PS provides active inspiratory assistance that directly affects minute ventilation and CO₂ clearance 2
- PEEP optimizes triggering mechanics and prevents alveolar collapse, but does not directly generate tidal volume 5, 4
- In patients with COPD, PEEP reduces work of breathing by offsetting intrinsic PEEP, but PS remains the primary ventilatory support 3, 6
Practical Application Across Settings
Non-Invasive Ventilation (NIV)
When presenting NIV settings, the format is consistently "IPAP/EPAP" or "PS over PEEP" 1:
- Example: "IPAP 20/EPAP 5" or "PS 15 over PEEP 5"
- High-pressure requirements in obesity hypoventilation syndrome are described as "IPAP >30, EPAP >8" 1
Invasive Mechanical Ventilation
For intubated patients on pressure support mode 2:
- Settings are presented as "PS 10 cmH₂O with PEEP 5 cmH₂O"
- Adjustments follow the sequence: optimize PS first, then titrate PEEP 2
Common Pitfalls to Avoid
Do not reverse the order, as this creates confusion about which parameter is being adjusted 2. The PS-first convention is universal across:
Avoid ambiguous phrasing such as "PEEP 5 with pressure support 10"—this reverses the conventional hierarchy and may lead to miscommunication during critical adjustments 2.