When your pulmonologist prescribes BiPAP therapy, the settings on your device are not arbitrary numbers — each figure is calibrated to your specific respiratory physiology. Understanding what they mean helps you monitor your therapy, communicate with your care team and recognise when settings may need adjustment.
IPAP (Inspiratory Positive Airway Pressure) is the pressure delivered when you inhale. It acts as the 'assist' — helping your lungs expand fully when your respiratory muscles are weak or your airway tends to collapse. Typical IPAP values range from 8 to 25 cmH₂O. A higher IPAP provides more breathing support but can feel overwhelming initially for new users.
EPAP (Expiratory Positive Airway Pressure) is the pressure maintained during exhalation. It serves two purposes: keeping the upper airway open against collapse (same principle as CPAP) and setting the baseline pressure from which IPAP rises. EPAP values typically range from 4 to 12 cmH₂O. The difference between IPAP and EPAP is called Pressure Support (PS) — it determines the mechanical work the device does for each breath.
Backup Rate (BPM) is a setting available on advanced BiPAP-ST (spontaneous/timed) models. It defines the minimum number of breaths per minute the device will deliver if your own breathing rate falls below the threshold. This is clinically critical for patients with central sleep apnea, hypoventilation, or neuromuscular conditions where spontaneous breathing may be insufficient during deep sleep.
Rise time controls how quickly the device ramps from EPAP to IPAP at the start of each breath — a faster rise feels more forceful, a slower rise feels gentler. Sensitivity determines how easily the device detects your inhalation effort. Both settings are often adjusted during a titration study. Never adjust IPAP, EPAP or backup rate without clinical guidance — incorrect settings can compromise your therapy or mask underlying deterioration.