Bilevel PAP and BPAP

Professional Explanation

EPAP serves a function similar to CPAP: it maintains airway patency during exhalation and prevents obstructive events. If a patient requires CPAP of 12 cm H₂O to eliminate obstructive apnea, EPAP would typically be set at or near that level.

IPAP provides additional pressure during inspiration. The higher pressure during inhalation can improve ventilation, increase tidal volume, and reduce the work of breathing. IPAP also contributes to upper airway patency during inspiration when collapsing forces are greatest.

Pressure support is the primary mechanism for ventilatory assistance. Increasing pressure support (widening the gap between IPAP and EPAP) increases mechanical assistance during inspiration — helpful when the patient has hypoventilation or when tidal volume needs augmentation.

Bilevel PAP may be considered when the patient cannot tolerate the expiratory pressure required on CPAP, when high CPAP pressures cause discomfort or arousals, when hypoventilation requires ventilatory support beyond airway splinting, or when higher pressure support is clinically indicated.

Titration Reasoning

EPAP is primarily adjusted to control obstructive events. If obstructive apneas or hypopneas persist, EPAP may need to be increased — just as CPAP would be increased.

IPAP (or pressure support) is adjusted to improve ventilation, increase tidal volume, address hypoventilation, or improve comfort. The technologist must know which pressure to adjust: EPAP for obstruction, pressure support for ventilation. Using the wrong adjustment will not solve the problem.

ELI-10

Bilevel PAP is like having two different fan settings: one for breathing in and one for breathing out. When you breathe in, the fan blows harder to help you take a deeper breath. When you breathe out, the fan eases up so you do not have to push as hard.

The lower pressure (EPAP) keeps your throat open, just like CPAP. The higher pressure (IPAP) gives you extra help breathing in. The difference between them is pressure support — the amount of extra help during each breath.

ELI Example

Think of riding a bicycle. EPAP is like the steady speed on flat ground. IPAP is like the extra push going uphill. Pressure support is the difference between the flat-ground effort and the uphill push. Bilevel PAP automatically gives that extra push with every breath.

Do Not Confuse

• IPAP vs EPAP — different purposes

• Pressure support (IPAP minus EPAP) vs IPAP alone

• Spontaneous bilevel PAP vs BPAP-ST (backup rate)

• Bilevel PAP and BPAP-ST are not the same mode

High-Yield Memory Anchors

• IPAP = pressure during inspiration; EPAP = pressure during expiration

• Pressure support = IPAP − EPAP

• EPAP controls obstruction (like CPAP)

• Pressure support assists ventilation

• Spontaneous bilevel PAP does not provide backup breaths

Chapter Recap

Bilevel PAP: IPAP for inspiration, EPAP for expiration. EPAP = airway splinting; pressure support = ventilatory assistance. Distinguish EPAP adjustments (obstruction) from pressure support adjustments (ventilation). Spontaneous mode has no backup breaths.

CHAPTER 5

Common Mistakes

• Adjusting IPAP for obstruction (adjust EPAP instead)

• Adjusting EPAP for hypoventilation (adjust pressure support instead)

• Assuming bilevel PAP provides backup breaths

• Confusing pressure support with IPAP

Safety and Scope

Bilevel PAP must be ordered. Titrate EPAP for obstruction and pressure support for ventilation within ordered parameters. Recognize when spontaneous mode is insufficient — for example, when central apneas occur and backup breaths are unavailable.