Minute ventilation

With minute ventilation (MV) is used in medicine and physiology refers to the volume of breathing air that turns per minute and is exhaled. It is the most commonly used respiratory time volume (tidal volume that is breathed in a unit of time ). An adult person breathes about 12 to 15 times per minute. He inhales a tidal volume of 500 to 700 ml per breath . His respiratory minute volume thus averages eight liters (13 × 600 ml = 7800 ml) per minute.

These values ​​are used, for example, for setting a ventilator or the consumption of an oxygen system.

Measurement

The minute ventilation is measured during the lung function test. It can be calculated relatively easily from the respiratory rate and the tidal volume.

Minute ventilation = tidal volume × respiratory rate

In ventilation machines, a target value and an actual value of the tidal volume are measured and displayed. In addition, it is often possible to distinguish between the spontaneous minute volume (provided by the patient) and the volume delivered by the machine. In addition, the tidal volume during inhalation is compared with the tidal volume during exhalation in order to be able to identify a leakage volume.

Minute ventilation during exercise

The minute volume can be increased three to four times during physical exertion. In well trained athletes, the maximum MV can increase up to 15 times the initial value.

Increase in minute ventilation (MV)

The MV is increased with physical exertion. There are also pathological conditions that increase MV:

• Every hyperventilation is accompanied by an increased respiratory minute volume, so at
  • fever
  • high altitude or thin air
  • Pulmonary embolism
  • Metabolic acidosis (over-acidification of the blood), which is compensated by hyperventilation
  • Disorders of the respiratory center

Decreased minute ventilation

During sleep , the minute volume sinks again below the daily rest value.

• When taking tranquilizers, the AMV decreases in higher doses.
• In people who are chronically adapted to an increased level of carbon dioxide , the administration of oxygen can lead to a decrease in the MV.
• Damage to the respiratory center can also reduce MV.

A reduced respiratory minute volume is also known as hypoventilation .

Individual evidence

1. ↑ Wildor Hollmann: Spiroergometry: cardiopulmonary performance diagnostics of healthy and sick; with 15 tables . Schattauer Verlag, 2006, ISBN 978-3-7945-2396-2 , pp. 92f.
2. ↑ Reinhard Larsen, Thomas Ziegenfuß: Ventilation: Basics and Practice . Jumper; April 24, 2009. ISBN 978-3-540-88811-6 . p. 172-.
3. ^ Physiology: 93 tables . Georg Thieme Verlag; 2010. ISBN 978-3-13-138411-9 . p. 256-.