Calculate predicted body weight from height, start volume control at 6-8 mL/kg PBW, PEEP 5-8, rate to match minute ventilation need, FiO2 to SpO2 92-96%, then check plateau and driving pressure and an ABG at 30 min.
At the bedside
Timed steps- 1
Measure height
0 minCalculate PBW: men 50 + 0.91 × (height cm − 152.4); women 45.5 + 0.91 × (height cm − 152.4). Never use actual weight for tidal volume.
- 2
Mode
0 minVolume assist-control (VC-AC) is a safe default: set Vt, rate, PEEP, FiO2, flow or Ti.
- 3
Tidal volume
0 min6-8 mL/kg PBW (6 mL/kg in ARDS). Non-ARDS patients: low (6) vs intermediate (8-10) Vt gave similar outcomes (PReVENT); avoid > 8.
- 4
Rate
0 min14-20/min; higher (25-30) if severe metabolic acidosis to match pre-intubation compensation; low (8-12) in asthma/COPD.
- 5
PEEP and FiO2
0 minPEEP 5-8 cmH2O; FiO2 1.0 initially, then titrate to SpO2 92-96% (88-92% in hypercapnic COPD).
- 6
Flow and I:E
0 minInspiratory flow 50-60 L/min (decelerating) or Ti ~0.8-1 s; I:E 1:2; longer expiration in obstructive disease.
- 7
Check mechanics
5 minInspiratory hold: plateau pressure (Pplat) ≤ 30 cmH2O; driving pressure (Pplat − PEEP) ≤ 15 cmH2O; expiratory hold for intrinsic PEEP.
- 8
ABG
30 minAdjust rate for pH/PaCO2 (new rate = old rate × old PaCO2 ÷ target PaCO2); adjust FiO2/PEEP for oxygenation.
- 9
Alarms and safety
OngoingSet high pressure alarm ~10 cmH2O above peak; low minute volume and apnoea alarms; head up 30-45°; sedation plan.
Predicted body weight and 6-8 mL/kg tidal volumes
| Height (cm) | PBW men (kg) | Vt 6-8 mL/kg men | PBW women (kg) | Vt 6-8 mL/kg women |
|---|---|---|---|---|
| 150 | 47.8 | 290-380 | 43.3 | 260-350 |
| 155 | 52.4 | 310-420 | 47.9 | 290-380 |
| 160 | 57.0 | 340-460 | 52.4 | 310-420 |
| 165 | 61.5 | 370-490 | 57.0 | 340-460 |
| 170 | 66.0 | 400-530 | 61.5 | 370-490 |
| 175 | 70.6 | 420-560 | 66.1 | 400-530 |
| 180 | 75.1 | 450-600 | 70.6 | 420-560 |
PBW = 50 (men) or 45.5 (women) + 0.91 × (height cm − 152.4).
Calculators for this topic
Predicted (ideal) body weight
ARDSNet predicted body weight from height and sex. Use for tidal volume, not for most drug doses.
Tidal volume from predicted body weight
Lung-protective tidal volume (usually 6 mL/kg PBW; range 4-8).
Driving pressure
Plateau pressure − PEEP (volume control, passive patient).
Static respiratory system compliance
Vt ÷ (Pplat − PEEP).
References
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First 30 minutes on the ventilator
Step 1 of ~7
Measure height → PBW → Vt 6-8 mL/kg
Based on Acute Respiratory Distress Syndrome Network. Educational use; follow local protocol.
Pathophysiology
Ventilator-induced lung injury arises from volutrauma (overdistension), barotrauma, atelectrauma (cyclic opening and closing) and biotrauma (inflammatory mediators). The aerated "baby lung" in ARDS can be small, so tidal volumes must be scaled to predicted, not actual, size.
Evidence
- ARMA (2000): 6 vs 12 mL/kg PBW with Pplat ≤ 30 reduced mortality in ARDS (31.0% vs 39.8%).
- PReVENT (2018): in non-ARDS ventilated patients, low (target 6) vs intermediate (target 10) Vt did not change ventilator-free days.
Controversies
- Optimal Vt in non-ARDS patients; driving pressure as a target remains observational.
🇮🇳 India notes
- Height is often not recorded in Indian ICUs; measure with a tape on the bed (heel to vertex) or estimate from ulna length. Write PBW on the ventilator chart.
References
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Test yourself
Module quiz · score 70% to complete the module
Educational reference for trained clinicians. Check doses against your hospital protocol and the patient in front of you.