Tidalvolumen

Tidalvolumen, or tidal volume (VT), is the amount of air moved into or out of the lungs during a normal breath. In clinical practice VT is measured in milliliters per breath and is commonly expressed relative to the person’s predicted body weight (PBW). In healthy adults VT typically ranges from about 400 to 700 mL, averaging around 500 mL, and is often described as roughly 7–8 mL per kilogram PBW.

Tidal volume contributes to minute ventilation, the total air entering or leaving the lungs per minute. Minute ventilation is the product of VT and the breathing frequency. Alveolar ventilation, which supports gas exchange, equals (VT minus dead space) times the respiratory rate, where dead space is the portion of each breath that does not participate in gas exchange.

Several factors influence VT. Body size, age, sex, posture, lung compliance, and airway resistance can alter the amount of air moved per breath. Disease states (such as obesity, COPD, or interstitial lung disease) and whether breathing is spontaneous or mechanically assisted also affect VT. VT can be measured directly with spirometry or estimated by ventilators in clinical settings.

Clinical significance and use include management of ventilation strategies in intensive care. In mechanical ventilation, protective strategies aim for lower VT, typically about 6 mL/kg PBW, to reduce volutrauma and barotrauma, with adjustments for conditions like ARDS or COPD. In spontaneous breathing, VT adapts to metabolic demand and can vary with activity, fatigue, or rehabilitation. In pediatrics, VT scales with weight and development, requiring careful, individualized adjustment.