skip to main content

BiPAP Pressure Support Calculation — FRCA Final MCQ

Instant feedback + full explanation. One question, done properly.

EasyIntensive Care MedicineBiPAP Pressure Support CalculationFRCA Final

A 55-year-old woman (ASA III) on the ICU has acute respiratory failure from pneumonia. Non-invasive ventilation is started using BiPAP. The IPAP is 18 cmH2O and EPAP is 6 cmH2O. What is the effective pressure support being delivered?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — 12 cmH2O

Pressure support = IPAP – EPAP = 18 – 6 = 12 cmH2O. IPAP (inspiratory positive airway pressure) provides the total inspiratory pressure; EPAP (expiratory positive airway pressure) provides PEEP/CPAP. The difference is the effective pressure support that augments the patient's inspiratory effort, reducing work of breathing. In hypercapnic respiratory failure (e.g., COPD exacerbation), the pressure support (IPAP-EPAP) determines the tidal volume augmentation and CO2 clearance. Increasing the pressure support (by increasing IPAP or decreasing EPAP) increases tidal volume.

Reference: BTS/ICS – 2016 – NIV guidelines; RCOA – 2023 – ICM ventilation