Mechanical Ventilation Tools

ARDSnet Calculator & Assistant

Use this ARDSnet calculator to estimate predicted body weight, choose lung-protective tidal volumes, and check whether a current PEEP/FiO₂ combination fits the low-PEEP or high-PEEP ARDSnet tables. This tool is built for ICU clinicians, respiratory therapists, students, and anyone learning practical ARDS ventilation strategy.

Pair this page with our IBW calculator, P/F ratio & oxygenation index tool, A–a gradient calculator, and causes of hypoxemia guide.

Open IBW CalculatorCheck P/F RatioRead ABG Guide

Initial Vent Settings

How to use this ARDSnet tool

  • Enter sex and height to estimate predicted body weight and lung-protective tidal volume targets.
  • Use the 4–6 mL/kg range to anchor ARDSnet-style low tidal volume ventilation.
  • Enter PaO₂, FiO₂, and PEEP to compare the patient’s current settings with the ARDSnet PEEP/FiO₂ table.
  • Reassess plateau pressure, pH, oxygenation, hemodynamics, and synchrony after any ventilator change.

Related PulmTools resources

Titration Assistant

ARDSnet Protocol Reference

INCLUSION CRITERIA: Acute onset of
1. PaO₂/FiO₂ ≤ 300 (corrected for altitude)
2. Bilateral (patchy, diffuse, or homogeneous) infiltrates consistent with pulmonary edema
3. No clinical evidence of left atrial hypertension

PART I: VENTILATOR SETUP AND ADJUSTMENT

1. Calculate predicted body weight (PBW):
 Males = 50 + 2.3 × [height (inches) - 60]
 Females = 45.5 + 2.3 × [height (inches) - 60]
2. Select any ventilator mode
3. Set ventilator settings to achieve initial Vₜ = 8 ml/kg PBW
4. Reduce Vₜ by 1 ml/kg at intervals ≤ 2 hours until Vₜ = 6 ml/kg PBW
5. Set initial rate to approximate baseline minute ventilation (not > 35 bpm)
6. Adjust Vₜ and RR to achieve pH and plateau pressure goals below

OXYGENATION GOAL: PaO₂ 55–80 mmHg or SpO₂ 88–95%

Use a minimum PEEP of 5 cm H₂O. Consider incremental FiO₂/PEEP combos (not required).
Lower PEEP/higher FiO₂ tier:
 FiO₂ 0.3 / 0.4 / 0.4 / 0.5 / 0.5 / 0.6 / 0.7 / 0.7 / 0.8 / 0.9 / 1.0
 PEEP 5 / 5 / 8 / 8 / 10 / 10 / 10 / 12 / 14 / 14 / 18–24

Higher PEEP/lower FiO₂ tier:
 FiO₂ 0.3 / 0.3 / 0.3 / 0.3 / 0.3 / 0.4 / 0.4 / 0.5 / 0.5 / 0.6 / 0.8 / 0.9 / 1.0
 PEEP 5 / 8 / 10 / 12 / 14 / 14 / 16 / 16 / 18 / 20 / 22 / 22 / 24

PLATEAU PRESSURE GOAL: ≤ 30 cm H₂O

Check Pplat (0.5s insp. pause) q4h and after any PEEP/Vₜ change:
• If Pplat > 30: ↓ Vₜ in 1 ml/kg steps (min = 4 ml/kg)
• If Pplat < 25 and Vₜ < 6: ↑ Vₜ in 1 ml/kg steps until Pplat ≥ 25 or Vₜ = 6
• If Pplat < 30 and breath stacking or dyssynchrony: ↑ Vₜ to 7–8 ml/kg if Pplat stays ≤ 30

pH GOAL: 7.30–7.45

Acidosis Management (pH < 7.30):
If pH 7.15–7.30: Increase RR until pH > 7.30 or PaCO₂ < 25 (Maximum set RR = 35).
If pH < 7.15: Increase RR to 35. If pH remains < 7.15, VT may be increased in 1 ml/kg steps until pH > 7.15 (Pplat target of 30 may be exceeded).
May give NaHCO₃.

Alkalosis Management (pH > 7.45): Decrease vent rate if possible.

I : E RATIO GOAL

Recommend that duration of inspiration be ≤ duration of expiration.

PART II: WEANING

A. Conduct a SPONTANEOUS BREATHING TRIAL daily when:

  1. FiO₂ ≤ 0.40 and PEEP ≤ 8 OR FiO₂ ≤ 0.50 and PEEP ≤ 5.
  2. PEEP and FiO₂ ≤ values of previous day.
  3. Patient has acceptable spontaneous breathing efforts. (May decrease vent rate by 50% for 5 minutes to detect effort.)
  4. Systolic BP ≥ 90 mmHg without vasopressor support.
  5. No neuromuscular blocking agents or blockade.

B. SPONTANEOUS BREATHING TRIAL (SBT):

If all above criteria are met and subject has been in the study for at least 12 hours, initiate a trial of UP TO 120 minutes of spontaneous breathing with FiO₂ ≤ 0.5 and PEEP ≤ 5:

  1. Place on T-piece, trach collar, or CPAP ≤ 5 cm H₂O with PS ≤ 5.
  2. Assess for tolerance as below for up to two hours:
    • SpO₂ ≥ 90 and/or PaO₂ ≥ 60 mmHg
    • Spontaneous VT ≥ 4 ml/kg PBW
    • RR ≤ 35/min
    • pH ≥ 7.3
    • No respiratory distress (distress = 2 or more):
      • HR > 120% of baseline
      • Marked accessory muscle use
      • Abdominal paradox
      • Diaphoresis
      • Marked dyspnea
  3. If tolerated for at least 30 minutes, consider extubation.
  4. If not tolerated, resume pre-weaning settings.

Definition of UNASSISTED BREATHING

(Different from the spontaneous breathing criteria as PS is not allowed)

  • Extubated with face mask, nasal prong oxygen, or room air
  • T-tube breathing
  • Tracheostomy mask breathing
  • CPAP ≤ 5 cm H₂O without pressure support or IMV assistance

ARDSnet quick questions

What tidal volume does ARDSnet usually target?

ARDSnet commonly targets about 6 mL/kg predicted body weight, with reduction toward 4 mL/kg when needed to control plateau pressure.

What oxygenation goal does ARDSnet use?

A typical ARDSnet oxygenation target is PaO₂ about 55–80 mmHg or SpO₂ about 88–95%, using paired PEEP and FiO₂ adjustments.

Why pair this with ABG and oxygenation tools?

ARDS ventilation is easier to manage when you look at acid-base status, oxygenation severity, and gas exchange together. Review the ABG interpretation guide, P/F ratio tool, and A–a gradient calculator.