With a volume breath type, the ventilator delivers a set tidal volume (VT) over a set inspiratory time. Airway pressures will vary depending on compliance and lung mechanics.
Normal volume range is 6 to 8 mL/kg of predicted body weight (PBW). Lung protective volume range is 4 to 6 mL/kg of predicted body weight.
Example: A 5’11” male will have a normal tidal volume range of about 450 mL to 600 mL.
Caution should be used with patients with restrictive and obstructive lung diseases as ventilating with too high of a tidal volume can lead to auto-PEEP (air trapping). This can cause to barotrauma and hemodynamic compromise.
Predicted body weight is calculated using the patient’s height and gender (see chart below).
