Minute Respiratory Volume Equals Respiratory
Rate Times Tidal Volume
The minute respiratory volume
is the total amount of new air moved into the respiratory passages each minute;
this is equal to the tidal volume
times the res-piratory rate per minute. The
normal tidal volume isabout 500 milliliters, and the normal respiratory rate is
about 12 breaths per minute. Therefore, the minuterespiratory
volume averages about 6 L/min. A personcan live for a short period with a
minute respiratory volume as low as 1.5 L/min and a respiratory rate of only 2
to 4 breaths per minute.
The respiratory rate occasionally rises to 40 to 50 per minute, and
the tidal volume can become as great as the vital capacity, about 4600
milliliters in a young adult man. This can give a minute respiratory volume
greater than 200 L/min, or more than 30 times normal. Most people cannot
sustain more than one half to two thirds these values for longer than 1 minute.