Vt is measured byspirometry, which is a non-invasive test.
It’s a measurement of the volume of inhaled and exhaled air over 60 seconds.
A typical adult VE ranges around 4 to 6 liters in 60 seconds.
Continuous positive airway pressure (CPAP) therapy can increase tidal volume and make breathing easier.
Alveolar Ventilation and Tidal Volume
Alveolarventilation (VA) is another important measurement related to tidal volume.
Dead space represents approximately a third of the air volume that’s moved during casual breathing.
Breathing harder can increase your alveolar ventilation.
Abnormal Tidal Volume Symptoms
Abnormally low and abnormally high tidal volume can cause a number of symptoms.
Abnormally Low Tidal Volume
A low Vt can be caused byhypoventilation(respiratory depression).
In the early stages of hypoventilation, you may not experience any symptoms.
Severe hypercapnia increases the level of hydrogen ions in your blood causing an increase in its acidity.
Abnormally High Tidal Volume
Hyperventilation (over-breathing) can cause a high Vt.
Symptoms associated with hyperventilation are often more distressing than hypoventilation.
Symptoms may include:
The noticeable symptoms are most common with acute hyperventilation.
The effects of chronic hyperventilation are not usually as obvious.
Among the signs to watch for are frequent and deep sighing, anxiety, and emotional distress.
The increase in Vt during pregnancy causes an increase in VE.
It is commonly increased with moderate exercise.
A pulmonologist or anesthesiologist will determine your ventilator configs.
Typically a respiratory therapist will manage the ventilator options, which guides your breathing pattern.
Your Vt plays an important role in your progression to getting off the ventilator.
High tidal volumes (greater than 10 mL/kg) can be harmful and may delay advancement to independent breathing.
Positive end-expiratory pressure (PEEP) is a setting on some mechanical ventilators.
Normal, or ideal, PEEP tweaks will depend on the individual and their condition.
Hallett, S.Physiology, tidal volume.
LoMauro A, Aliverti A.Respiratory physiology of pregnancy: Physiology masterclass.Breathe (Sheff).
2017;5(14):288. doi:10.21037/atm.2017.06.64
