Question

Use the following data from a patient's medical chart to answer the next 3 questions
Blood Pressure.................................... 98/60 (mm Hg)
Heart Rate........................................... 104 BPM
Central Venous Pressure.................... 3 mm Hg
Respiratory Rate (f)............................. 18 breaths/min
Tidal Volume (VT)……………………... 350 ml/breath
Dead Space (VD)................................. 200 ml/breath
Total Lung Capacity (TLC)..................   6.9 L
(Forced) Vital Capacity (FVC)………..    4.8 L
PaO2 .........[normal O2 = 100] 70 mm Hg
PaCO2 .......[normal CO2 = 40] 50 mm Hg
pHa...................................................... 7.32
[HCO3-]................................................ 30 mEq/L
This patient's Alveolar Minute Ventilation (VA) is _______ L/min

A. 1.5
B. 1.8
C. 2.25
D. 2.7
E. 3.5
F. 3.75
G. 5.25
H. 5.4

I. 6.3

Answer 1

Alveolar minute ventilation

Alveolar ventilation is the amount of gas that enter alveoli per min.

It can be calculated by the following formula

Alveolar ventilation = ( tidal volume_ dead space ) × respiratory rate

Here,

Tidal volume=350ml / breath

Dead space=200 ml/ breath

Respiratory rate=18 bt/ min

So

Alveolar ventilation ( VA) = (tidal volume _ dead space)× respiratory rate

VA=( 350 ml/ breath _200 ml/ breath )× 18 breath/ min

VA= 50ml/ breath × 18 breath/ min = 2700ml/ min

Now convert ml/ min to liter/ min by dividing by 1000

2700ml/ min ÷ 1000= 2.7 L/ min