Is pressure support the same as inspiratory positive airway pressure (IPAP)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: February 6, 2026 • View editorial policy

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.

Ask Question

Pressure Support vs IPAP: Understanding the Relationship

Pressure support (PS) and inspiratory positive airway pressure (IPAP) are not the same thing—pressure support is the difference between IPAP and EPAP, while IPAP is the absolute pressure level delivered during inspiration. 1, 2

Key Definitions

  • IPAP is the higher pressure level delivered during the inspiratory phase of bi-level positive airway pressure (BiPAP/BPAP) ventilation 1, 2

  • EPAP (expiratory positive airway pressure) is the lower pressure maintained during expiration 1, 2

  • Pressure support is calculated as the mathematical difference: PS = IPAP - EPAP 1, 2, 3

How This Works Mechanically

  • The IPAP provides the actual ventilatory support during inspiration by generating higher pressure that overcomes lung and chest wall impedance 3

  • The pressure support (IPAP-EPAP difference) is what actually augments tidal volume and improves ventilation 1, 2, 3

  • EPAP serves multiple functions: it maintains upper airway patency, recruits underventilated lung tissue, offsets intrinsic PEEP, and actively flushes exhaled CO₂ from the circuit 1, 3, 4

Clinical Example

  • If you set IPAP at 15 cm H₂O and EPAP at 5 cm H₂O, the pressure support is 10 cm H₂O 2

  • If you set IPAP at 20 cm H₂O and EPAP at 10 cm H₂O, the pressure support is still 10 cm H₂O—same pressure support but different absolute pressures 2

  • Typical initial settings start with IPAP 8-10 cm H₂O and EPAP 4-5 cm H₂O, providing pressure support of 4-6 cm H₂O 3

Why This Distinction Matters Clinically

  • When titrating BiPAP, you must adjust both IPAP and EPAP independently to optimize both ventilation (via pressure support) and airway patency/PEEP effects (via EPAP) 1, 2

  • Inadequate EPAP (<3 cm H₂O) allows CO₂ rebreathing in single-limb circuits, negating the ventilatory benefits of higher IPAP 3

  • The IPAP-EPAP difference (pressure support) is what determines the delivered tidal volume, not IPAP alone 1, 2, 3

Common Pitfall to Avoid

  • Do not confuse "pressure support ventilation" (PSV) mode—where you set a single pressure support level above PEEP—with the pressure support value in BiPAP, which is derived from two separately set pressures 1

  • In assisted spontaneous breathing (pressure support mode), you typically set one pressure value, whereas in bi-level support you set both IPAP and EPAP independently 1

References

2
Guideline

best clinical practices for the sleep center adjustment of noninvasive positive pressure ventilation (nppv) in stable chronic alveolar hypoventilation syndromes.

Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 2010

3
Guideline

BiPAP Therapy for Respiratory Disorders

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

4
Guideline

Alternative Modes of Mechanical Ventilation for Refractory Hypoxemia and Ventilator Asynchrony

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Related Questions

What is the difference between automatic bilevel positive airway pressure (auto‑BiPAP) and automatic servo‑ventilation (auto‑SV)?
What are the standard BiPAP settings for inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP/PEEP) when they need to be increased?
What are the guidelines for using a Bi-Level Positive Airway Pressure (BiPAP) device and its contraindications?
What are the recommended initial settings for Minimum Pressure (MINP) and Maximum Pressure (MAXP) in Adaptive Ventilation (AVAPS)?
What does a BiPAP setting of 16/4 (inspiratory positive airway pressure 16 cm H₂O and expiratory positive airway pressure 4 cm H₂O) mean?
How long should ciprofloxacin be administered for an uncomplicated urinary tract infection compared with a complicated infection?
In a 63-year-old man with known sarcoidosis and an elevated ferritin level, what is the most appropriate initial evaluation and management?
In an acute COPD exacerbation with hypercapnic respiratory failure (pH < 7.35, PaCO₂ > 45 mm Hg) and no contraindications, when and how should non‑invasive ventilation be initiated and managed?
What medication with proven cardiovascular benefit should be added for a patient with type 2 diabetes mellitus and established coronary artery disease who is already taking metformin and glyburide?
How do functional and non‑functioning pituitary adenomas affect hormone secretion and what are the first‑ and second‑line treatment options?
Does vitamin D deficiency worsen Raynaud phenomenon and should I supplement vitamin D to improve symptoms?

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.