What are the recommended settings and considerations for using a volume‑targeted (targeted volume) ventilation mode?

Volume-Targeted Ventilation Mode: Settings and Considerations

In volume-targeted ventilation, set an initial tidal volume of 6 mL/kg predicted body weight with plateau pressure maintained ≤30 cmH₂O, as this approach reduces mortality in ARDS and prevents ventilator-induced lung injury across most clinical contexts. 1, 2, 3

Core Mechanism and Rationale

Volume-targeted ventilation operates by having the clinician set a specific tidal volume to be delivered, with the ventilator generating whatever pressure is necessary to achieve this volume within the set inspiratory time 4. This differs fundamentally from pressure-targeted modes where pressure is fixed and volume varies based on lung compliance.

The physiologic advantage is straightforward: controlling delivered volume prevents the overdistension and repetitive alveolar injury that drives ventilator-induced lung injury, particularly in diseased lungs with heterogeneous compliance 1.

Initial Ventilator Settings

Tidal Volume

• Start at 6 mL/kg predicted body weight (PBW) for ARDS and most acute respiratory failure 1, 2, 3
• PBW calculation: Males = 50 + 0.91[height(cm) - 152.4] kg; Females = 45.5 + 0.91[height(cm) - 152.4] kg 3
• Acceptable range: 4-8 mL/kg PBW, with lower volumes (even <6 mL/kg) potentially beneficial in severe ARDS 1
• For surgical patients: 6-8 mL/kg PBW initially 5

Plateau Pressure

• Maintain plateau pressure ≤30 cmH₂O as the upper safety limit 1, 2, 3
• This threshold prevents excessive alveolar stretch even when chest wall compliance is reduced
• If plateau pressure exceeds 30 cmH₂O despite appropriate tidal volume, consider permissive hypercapnia rather than increasing volume 4, 6

Driving Pressure

Driving pressure (ΔP = plateau pressure - PEEP) is the single best predictor of outcomes in ARDS, with values >15 cmH₂O indicating high risk 1. This reflects the functional lung size available for ventilation. When driving pressure is low despite standard tidal volumes, you may have more flexibility; when elevated, prioritize reducing it over strict adherence to other targets.

PEEP Settings

• Initial PEEP: 5 cmH₂O 5
• For moderate-to-severe ARDS: use higher PEEP levels (typically 10-15 cmH₂O) 2
• PEEP prevents end-expiratory alveolar collapse and reduces repetitive recruitment/derecruitment injury 4
• In obstructive disease, PEEP may offset intrinsic PEEP to reduce work of breathing, but setting PEEP above intrinsic PEEP is harmful 4

Respiratory Rate and Timing

• Rate: 10-15 breaths/min for restrictive disease; adjust based on minute ventilation needs 4
• Inspiratory time (Ti): Must be sufficient to deliver the set volume without excessive peak pressures
  • Typical Ti: 1.2-1.6 seconds (30-40% of breath cycle) 7
  • Shorter Ti in obstructive disease to allow adequate expiratory time
  • Longer Ti in restrictive disease to accommodate reduced compliance 7
• I:E ratio: 1:2 to 1:1.4 depending on pathology 4

Disease-Specific Adjustments

ARDS

• Tidal volume: 6 mL/kg PBW (strong evidence for mortality reduction) 1, 2, 3
• Plateau pressure: ≤30 cmH₂O
• Higher PEEP (10-15 cmH₂O) combined with low tidal volume shows mortality benefit 1
• Permissive hypercapnia is acceptable with pH >7.20 4, 6
• Consider prone positioning if PaO₂/FiO₂ <150 2

COPD/Obstructive Disease

• Allow longer expiratory time to prevent gas trapping 4
• Lower I:E ratio (more time for exhalation)
• Monitor for intrinsic PEEP; set external PEEP cautiously 4
• Target higher pCO₂ if baseline is chronically elevated (inferred from high bicarbonate) 4

Neuromuscular Disease/Chest Wall Deformity

• May require higher pressures (10-15 cmH₂O) to overcome chest wall stiffness 4
• Tidal volume: 6 mL/kg PBW
• Higher respiratory rates (15-25 breaths/min) may be needed 4
• I:E ratio closer to 1:1 4

Critical Pitfalls to Avoid

1. Do not chase normal blood gases aggressively: Permissive hypercapnia with pH >7.20 is safer than high tidal volumes or pressures 4, 6

2. Plateau pressure >30 cmH₂O is a hard stop: If this occurs with appropriate tidal volumes, accept higher CO₂ rather than increasing volume 1, 4

3. Volume-targeted modes do NOT compensate for leaks like pressure modes do: This is a major disadvantage in non-invasive ventilation where mask leak is inevitable 4. For NIV, pressure-targeted modes are strongly preferred 4

4. Driving pressure matters more than tidal volume alone: A patient receiving 6 mL/kg with driving pressure of 18 cmH₂O is at higher risk than one receiving 7 mL/kg with driving pressure of 12 cmH₂O 1

5. Avoid sudden pressure increases: Volume modes deliver whatever pressure is needed, which can cause discomfort and patient-ventilator dyssynchrony if lung compliance suddenly worsens 4

Monitoring and Adjustment

• Measure plateau pressure regularly (at least every 4-6 hours and with any clinical change)
• Calculate driving pressure with each plateau pressure measurement
• Adjust tidal volume downward if plateau pressure approaches 30 cmH₂O or driving pressure exceeds 15 cmH₂O
• Monitor for patient-ventilator dyssynchrony: Volume modes are less forgiving of changes in patient effort
• Target SpO₂ 92-97% or PaO₂ 70-90 mmHg; avoid hyperoxia 1

When Volume-Targeted Ventilation Is NOT Preferred

Volume-targeted modes are rarely used for non-invasive ventilation in the UK and most centers because they cannot compensate for mask leak, deliver uncomfortable pressure spikes, and lack the expiratory pressure support needed for CO₂ clearance 4. For NIV, pressure-targeted bi-level modes are strongly preferred.

Evidence Strength

The recommendation for low tidal volume (6 mL/kg PBW) with plateau pressure ≤30 cmH₂O in ARDS represents Level 1++ evidence with strong recommendations from multiple high-quality guidelines 1, 2, 3. The landmark ARDS Network trial demonstrated absolute mortality reduction from 40% to 31% with this strategy, making it one of the most robust findings in critical care medicine.