Question

Use the following information to answer the questions below: A 70 Kg woman is about to begin a bike ergometer ride at a resistance of 3.0 kp, and 60 rpm. The volume of her respiratory areas not involved in gas exchange is 140 ml.

a. At rest her rate of breathing is 15 b/min and tidal volume is 450 ml. Her VE is?

b.After two minutes into the work her breathing rate is 35 b/min and her VE is 70 L/min. What is her tidal volume?

c. After three minutes her VE is 75 l/min, breathing frequency is 35 b/min. What is her alveolar ventilation per minute?

d. After reaching “steady state” her VO2 is 2.5 l/min, breathing frequency is 36 b/min and ventilatory equivalent is 33. Her VE is?

Answer 1

Minute ventilation (VE) = tidal volume x breathing rate.
a) tidal volume = 450ml

breathing rate = 15b/min

VE = 450ml x 15b/min = 6750ml/min

b) breathing rate = 35b/min

Ve = 70l/min or 70000ml/min

tidal volume = Ve/breathing rate = 70000/35 = 2000 ml or 2 L

c) VE = 75 L or 75000 ml

breathing rate = 35b/min

dead space = 140ml

tidal volume = 75000/35 = 2143ml

Alveolar ventilation per minute = ([tidal volume − dead space] × respiratory rate)

Alveolar ventilation/min= ([2142.85 - 140] x 35) = 70100ml/min.

d) ventilatory equivalent is the measure of ratio of minute ventilation/ oxygen consumption

ventilatory equivalent = VE/VO2 ;

VE = ventilatory equivalent x VO2

ventilatory equivalent = 33

VO2 = 2.5L/min

VE = 33 x 2.5 = 82.5 L/min