WALL REF 02 · FIELD REFERENCE

BiPAP / NIV

Two pressures, two jobs — set it, read it, know when to bail
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18 × 24 IN · WALL REFERENCE
GoldOxygenation — EPAP / PEEP · FiO₂
OliveVentilation & work — IPAP · the PS gap
RustDanger / limits / failure → intubate
1CPAP vs BiPAPone level or two
CPAP · ONE PRESSURE splint open · oxygenate BiPAP · TWO PRESSURES IPAP EPAP + inspiratory boost = ventilate

CPAP holds one steady pressure — recruit & oxygenate (flash edema, OSA). BiPAP adds a higher IPAP on every breath — that extra push does the ventilating (COPD, hypercapnia).

2Why It Rescues the Heartflash pulmonary edema
↑ Intrathoracic Ppositive pressure squeezes the chest
→
↓ Preloadless venous return → less pulmonary congestion
→
↓ LV Afterloadlower transmural wall stress → LV empties easier

NIV wrings water out of the lungs by unloading the pump, not by drying it. Symptoms improve fast; the 3CPO trial found no mortality change vs O₂ — so it's adjunctive to nitrates/diuresis, buying time.

3Disease → Target → Startranges · titrate to effect
DISEASETARGETSTART (cmH₂O)
COPD /
hypercapnic		 Blow off CO₂ — widen the PS gap IPAP 10–15
EPAP 4–5
↑IPAP q2–5 to effect
Cardiogenic
edema		 Recruit & oxygenate; unload LV CPAP 8–10
or BiPAP w/
higher EPAP
Asthma
⚠ caution		 Air-trapping & barotrauma risk — low threshold to intubate Lower press.
watch closely
no delay
OHS /
obesity		 Overcome chest-wall load Higher IPAP
(often 18–24)
EPAP 6–8

Ranges are educational starting points — titrate to ABG, Vt, comfort & SpO₂ per local protocol. Not a prescriptive order.

S/TModes & Termswhat the buttons mean
TERMWHAT IT DOES
CPAPOne continuous pressure — no inspiratory boost. Oxygenation only.
S · SpontPatient triggers every breath; no backup if they tire.
S/TSpontaneous + a timed backup rate if apneic — the safe default.
Backup RRTimed breaths/min delivered if no trigger (e.g. 10–14).
Rise timeHow fast it ramps up to IPAP — tune for comfort.
MMask & Leak Pearlsthe interface makes or breaks it
  • Oro-nasal first-line — mouth-breathing dyspneic patients leak out of nasal-only masks.
  • Size & seal — smallest mask that covers; a small leak is normal, the vent compensates.
  • Coach, don't clamp — let them hold it first; a fought mask fails. Ramp pressures up gently.
  • Watch eyes & bridge — upward leak dries corneas; pad the nasal bridge early to prevent sores.
  • Full stomach = risk — gastric insufflation & vomiting; keep head up, consider NG if prolonged.
4Read the Two Pressurespressure vs time —
the whole machine in one trace
NIV PRESSURE–TIME baseline sits at EPAP, not zero
INSPIRATION EXPIRATION PRESSURE cmH₂O 0 PRESSURE SUPPORT IPAP − EPAP = VENTILATION IPAP inspiratory boost — the push you feel EPAP = PEEP · splints alveoli · oxygenation · offsets auto-PEEP TIME → each rise = one breath the patient triggers
Two knobs, two jobs — read the gas, turn the matching pressure
CO₂ HIGH · pH LOW · ventilation problem
↑ IPAP
Widen the gap. A bigger IPAP−EPAP → bigger tidal volume → more CO₂ blown off. Titrate IPAP up in ~2 cmH₂O steps to comfort & Vt.
O₂ LOW · SpO₂ down · oxygenation problem
↑ EPAP / FiO₂
Recruit & enrich. Higher EPAP holds more alveoli open; raise FiO₂ alongside. Bump IPAP with EPAP so the support gap holds.
The whole card: IPAP moves air (CO₂), EPAP holds the lung open (O₂). They set almost independently — change one gas, turn one pressure.
5Titration Algorithma time-limited trial
1
Explain & coach. Hold the mask to the face, low pressures first, talk them through it. Tolerance is step one — a fought mask fails.
2
Start & seal. e.g. IPAP 10–12 / EPAP 4–5; confirm chest rise, exhaled Vt > 5 mL/kg, minimal leak.
3
CO₂ still high? ↑ IPAP in ~2 cmH₂O steps (widen the gap) toward Vt & comfort — commonly up toward 20–30 as tolerated.
4
O₂ still low? ↑ EPAP in 2–5 cmH₂O and/or ↑ FiO₂ for SpO₂ ≈ 88–92% (COPD) / ≥ 94% (edema).
5
Recheck ABG at ~30–60 min. Improving pH/PaCO₂ = the trial is working. No improvement → escalate — see the failure box.
⊕The Four Dialseverything you actually set
IPAP olive
Inspiratory pressure → tidal volume → CO₂ / ventilation.
EPAP gold
= PEEP. Splints alveoli → O₂ / oxygenation.
FiO₂ gold
Oxygen fraction — the other oxygenation lever alongside EPAP.
Backup · Rise olive
S/T backup rate catches apnea; rise time tunes comfort.

Two gases, two knobs — IPAP and EPAP set almost independently. Change the gas that's wrong, turn its dial; recheck, repeat.

!Contraindicationsscreen before you strap
Absolute tube now
  • Apnea / respiratory or cardiac arrest
  • Can't protect the airway / obtunded
  • Facial trauma, burns, or fixed obstruction
  • Active vomiting or upper-GI bleed
  • Hemodynamic instability / shock
Relative weigh it
  • Agitation / poor cooperation
  • Copious secretions
  • Severe / life-threatening hypoxemia
  • Recent facial or upper-GI surgery
  • Undrained pneumothorax
!Failure → Intubatereassess at ~1–2 h
NIV is a trial — don't ride a losing one⚠ CALL EARLY
  • ABG / pH worse after a trial
  • Rising or unchanged CO₂
  • Falling mental status / GCS
  • Hemodynamic instability
  • Exhaustion, rising RR
  • Can't protect the airway
  • No improvement in ~1–2 h
  • Mask intolerance despite coaching
A failing NIV trial is a delayed intubation — set the clock, prep the tube in parallel.
6Worked Caseswalk the numbers
COPD exacerbationpH 7.28
pH 7.28 · PaCO₂ 65 · SpO₂ 89% on 2L Acidosis from retained CO₂ = a ventilation problem. Start BiPAP IPAP 12 / EPAP 5. Coach, seal, confirm Vt. ↑ IPAP stepwise (12→14→16) to widen the gap; recheck gas at 30–60 min.
Flash pulmonary edemaSpO₂ 84%
Crackles · diaphoretic · SpO₂ 84% · CO₂ not the issue An oxygenation + preload problem. CPAP 10 + FiO₂ (or BiPAP, higher EPAP) with nitrates/diuresis. Watch response — fast symptom relief is expected; treat the heart underneath.
Failing trial at 1 hpH ↓ GCS ↓
1 h in: pH 7.22 (was 7.28) · GCS drifting · RR climbing Gas worse, mental status dropping — the trial failed. Intubate. Don't re-titrate a losing NIV trial into a crash airway.
◐At the Bedsidewhat to watch
  • Exhaled Vt — aim > 5–6 mL/kg; too low = not ventilating.
  • Leak — big leaks kill trigger & Vt; reseat before you crank pressure.
  • RR & effort — a falling rate & calmer patient = it's working.
  • Sync — fighting / mistriggering → adjust rise time, trigger, mask.
  • Mental status — new drowsiness can mean rising CO₂, not comfort.
  • ABG clock — recheck ~30–60 min, then again at ~1–2 h.
Escalation Ladder
Nasal O₂→ HFNC→ CPAP / BiPAP→ INTUBATE

Move up a rung when the one below fails — but don't stall on NIV past its trial window.

≥7.35
pH goal on NIV
88–92%
SpO₂ · COPD target
1–2 h
reassess — improve or bail
REMEMBER — IPAP moves CO₂ · EPAP moves O₂ · the gap (IPAP−EPAP) is your ventilation · a failing NIV trial is a delayed tube.
Sheet
BiPAP / NIV
Series / No.
WALL REF 02
Part No.
CC-WR-02
Rev
B
Status
FIELD REFERENCE — NOT A PROTOCOL. VERIFY LOCALLY.

SOURCES: BTS/ICS Guideline, Thorax 2016;71:ii1 (acute hypercapnic RF: start IPAP ~10–16 / EPAP 4–6, titrate to Vt, recheck ABG) · ERS/ATS NIV Guideline, Eur Respir J 2017;50:1602426 · 3CPO (Gray), NEJM 2008;359:142 (ACPE: faster relief, no mortality change) · GOLD COPD Report · StatPearls, Noninvasive Ventilation (contraindications). © 2026 Claustrum LLC d/b/a Crash Card · crashcard.co · Printed in Minnesota.