- Enter the patient's height and choose the unit (cm or inches), then select sex. These two fields drive the ideal body weight (Devine) and all the tidal-volume targets — predicted body weight is set by height and sex, never by actual weight.
- The tool shows the target tidal volume at your chosen mL/kg (default 6) plus the 4 and 8 mL/kg bounds. Adjust the mL/kg field if you are aiming for a different lung-protective target.
- Optionally enter the respiratory rate to compute minute ventilation, and the set/measured tidal volume to see the actual delivered mL/kg IBW.
- If a measured Vt is entered, the result flags whether the delivered volume is lung-protective (4–8 mL/kg), borderline (8–10), or excessive (>10 mL/kg).
All computation runs in your browser; no values are stored or transmitted.
When to Use
Use this tool whenever you set up or review invasive mechanical ventilation and want to dose the tidal volume by predicted body weight. It is essential in ARDS and acute respiratory failure, where lung-protective ventilation (6 mL/kg IBW, range 4–8) with plateau pressure ≤30 cm H₂O is the standard of care, but it applies to any ventilated patient: dosing Vt by actual body weight systematically over-distends the lungs of short and obese patients. Add the respiratory rate to estimate minute ventilation when titrating PaCO₂.
Appropriate population
Intubated, mechanically ventilated adults — particularly those with ARDS or at risk of ventilator-induced lung injury. Useful at intubation to set an initial lung-protective Vt, and at the bedside to audit whether the currently delivered tidal volume falls within the 4–8 mL/kg IBW band. In the ICU and AKI patient, limiting ventilator-induced injury and systemic inflammation helps preserve kidney perfusion.
When NOT to rely on it
Tidal-volume targets are a starting framework, not a substitute for full ventilator management: always co-titrate to plateau pressure (≤30 cm H₂O), driving pressure, PEEP, oxygenation, and pH. The Devine IBW formula is validated for adults and becomes unreliable at extremes of height (especially height <60 in / ~152 cm, where the equation can drive IBW very low). It does not account for chest-wall or abdominal compliance, and it is not intended for paediatric patients.
Pearls & Pitfalls
Dose by predicted, not actual, weight
Tidal volume in lung-protective ventilation is set per kilogram of ideal (predicted) body weight, which depends only on height and sex. A 100 kg patient and a 60 kg patient of the same height and sex get the same target Vt. Using actual body weight is the single most common error and reliably over-distends the lungs of short, obese, or oedematous patients.
Pair Vt with plateau pressure
ARDSNet targets 6 mL/kg IBW (range 4–8) and a plateau pressure ≤30 cm H₂O. If the plateau pressure is high at 6 mL/kg, step the Vt down toward 4 mL/kg; if a lower Vt causes dyssynchrony or severe acidaemia, you may move up toward 8 mL/kg while keeping the plateau in check. Minute ventilation (Vt × RR) is what you titrate to PaCO₂.
Pitfalls
(1) Entering measured (actual) weight instead of height/sex — predicted body weight is height-driven only. (2) At very short stature (<60 in / ~152 cm) the Devine equation drives IBW low; sanity-check the result and use clinical judgment. (3) A "normal-looking" 8–10 mL/kg Vt is often not lung-protective for the patient's predicted weight — check the actual mL/kg, not the absolute mL. (4) Minute ventilation alone does not confirm adequacy of gas exchange; always confirm with an arterial blood gas.
Why Use It
The landmark ARDSNet trial showed that ventilating with a lower tidal volume (6 mL/kg of predicted body weight) and limiting plateau pressure reduced mortality compared with traditional higher volumes, by minimizing ventilator-induced lung injury and the inflammatory cascade (volutrauma and biotrauma) it triggers. Because tidal volume must be dosed by predicted body weight, a fast bedside computation of IBW and the 4–8 mL/kg targets is essential to applying this evidence correctly — eyeballing an absolute mL value is unreliable. Limiting that systemic inflammatory injury also matters for the kidneys: lung-protective ventilation helps preserve renal perfusion and may reduce ventilator-associated acute kidney injury in critically ill patients.
Minute Ventilation & Tidal Volume — Lung-Protective Targets
Enter height and sex to get the ideal body weight (Devine) and the lung-protective tidal-volume targets. Optionally add the respiratory rate and the set/measured tidal volume to compute minute ventilation and the actual delivered mL/kg IBW.
⚕ Tidal volume is dosed by predicted body weight (height + sex), never actual weight. ARDSNet targets 6 mL/kg IBW (range 4–8) with plateau pressure ≤30 cm H₂O. These targets are a starting framework — co-titrate to plateau/driving pressure, PEEP, oxygenation, and pH. For licensed clinicians; not a substitute for individualized assessment.
Next Steps
Use the IBW and target Vt to set and audit lung-protective ventilation, then verify with bedside measurements.
- Set the initial tidal volume to the 6 mL/kg IBW target (range 4–8). If the measured Vt computes to >8 mL/kg IBW, reduce it toward 6 mL/kg.
- Check the plateau pressure: keep it ≤30 cm H₂O. If plateau is high at 6 mL/kg, step Vt down toward 4 mL/kg and reassess.
- Titrate minute ventilation (Vt × RR) to the target PaCO₂/pH on an arterial blood gas; raise RR before raising Vt when more clearance is needed.
- Pair this with the P/F ratio to grade oxygenation severity and the A-a gradient to characterise the gas-exchange defect.
Evidence & References
Formulas
| Quantity | Formula |
|---|---|
| Height (inches) | cm ÷ 2.54 (or use inches directly) |
| IBW — Male (kg) | 50 + 2.3 × (heightin − 60) |
| IBW — Female (kg) | 45.5 + 2.3 × (heightin − 60) |
| Target tidal volume (mL) | target mL/kg × IBW (kg) |
| Minute ventilation (L/min) | (VtmL × RR) ÷ 1000 |
| Actual Vt per kg IBW | measured Vt (mL) ÷ IBW (kg) |
Lung-Protective Tidal Volume Targets
| Actual Vt (mL/kg IBW) | Interpretation |
|---|---|
| 4–8 mL/kg | Lung-protective (ARDSNet 6 mL/kg, range 4–8) |
| 8–10 mL/kg | Borderline — consider reducing toward 6 mL/kg |
| >10 mL/kg | Excessive — not lung-protective; risk of volutrauma |
The ARDSNet (ARMA) trial established lower tidal volume (6 mL/kg predicted body weight) with plateau pressure ≤30 cm H₂O as standard lung-protective ventilation, reducing mortality versus traditional higher volumes. Ideal body weight uses the Devine equation; ATS/ESICM/SCCM guidance endorses low-tidal-volume ventilation in ARDS.
References
- Acute Respiratory Distress Syndrome Network; Brower RG, Matthay MA, et al. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med. 2000;342(18):1301–1308.
- Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650–655.
- Fan E, Del Sorbo L, Goligher EC, et al. An official American Thoracic Society/European Society of Intensive Care Medicine/Society of Critical Care Medicine clinical practice guideline: mechanical ventilation in adult patients with acute respiratory distress syndrome. Am J Respir Crit Care Med. 2017;195(9):1253–1263.
