Question

My question is: Should the patient be concerned based on their % predicted value? Why or why not?

Determine the patient’s actual vital capacity from the spirogram. Then calculate and analyze the patient’s % predicted vital capacity if the patient’s predicted vital capacity is 5200 ml.

1. 1. Actual vital capacity = 5000 ml
      • 6000 ml 1000 ml = 5000 ml
2. 2. Predicted Vital capacity = 5200 ml
   3. % predicted vital capacity = 96.15%
      • (5000 ml / 5200 ml) x 100 = 96.15%

Answer 1

The actual vital capacity can be calculated from spirometry. It is the measure of total volume of air can be expelled into the mouthpiece of spirometry following a full inhalation. The Measured column shows the total volume of vital capacity in liters. In general, it is about 4800mL and varies a little with respect to age and body size.

The formula to find the vital capacity is,

VC = TV+IRV+ERV.

The summation of tidal volume, inspiratory reserve volume, and expiratory reserve volume.

The predicted column of vital capacity is calculated value based on gender, age and height and comapred to the average of the normal total volume of similar subject. Predicted value is calculated via the following formulas:

Vital capacity for men (in litres) = ((27.63 –112 x Age in years) x Height in cm) / 1000.

Vital capacity for women (in litres) = ((21.78 –101 x Age in years) x Height in cm) / 1000.

% predicted vital capacity :

Actual vital capacity = 6000 ml 1000 ml

Predicted Vital capacity = 5200 ml

% predicted vital capacity = (6000/5200)*100 = 115.38%

Actual vital capacity = 1000 ml

Predicted Vital capacity = 5200 ml

% predicted vital capacity = (1000/5200)*100 = 19.23%

There should be a concern about  % predicted value because it reflects the deviation of actual value from thr predicted value. Predicted value is the average value based on the age and gender.