# If a patient's tidal volume is 400 ml, their respiratory rate is 15 breaths/min, and their dead space volume is 120 ml, their alveolar ventilation (VA) and pulmonary ventilation (VP) are respectively: a) 6000 and 7800 ml/min b) 6000 and 4200 ml/min c) 7800 and 6000 ml/min d) 4200 and 6000 ml/min

Medicine · Middle School · Tue Nov 03 2020

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Alveolar ventilation (VA) refers to the volume of air that reaches the alveoli (the gas exchange regions in the lungs) and participates in gas exchange with the blood per minute. Pulmonary ventilation (VP), also known as minute ventilation, refers to the total volume of air a person breathes in and out in a minute.

Given:

Tidal Volume (VT) = 400 ml

Respiratory Rate (RR) = 15 breaths/min

Dead Space Volume (VD) = 120 ml

First, let's calculate the pulmonary ventilation (VP):

**VP = Tidal Volume (TV) × Respiratory Rate (RR)**

VP = 400 ml/breath × 15 breaths/min VP = 6000 ml/min

Now we need to calculate the alveolar ventilation (VA): Since only the part of the tidal volume that isn't dead space volume reaches the alveoli, we subtract the dead space volume (VD) from the tidal volume to find the volume of air per breath that actually reaches the alveoli. Then we multiply it by the respiratory rate.

VA = (Tidal Volume (TV) - Dead Space Volume (VD)) × Respiratory Rate (RR) VA = (400 ml - 120 ml) × 15 breaths/min VA = 280 ml/breath × 15 breaths/min VA = 4200 ml/min

Therefore, the alveolar ventilation (VA) is 4200 ml/min and the pulmonary ventilation (VP) is 6000 ml/min. **So the answer is d) 4200 and 6000 ml/min.**