Monday, June 29, 2020

Predicted normal body

Q: In LOW TIDAL VOLUME VENTILATION (LTVV) for patients with ARDS, tidal volume (TV) should be adjusted according to? (select one)

A) Ideal body weight
B) Predicted body weight

Answer:  B

There is a difference between ideal body weight and the predicted body weight.

 Ideal body weight (IBW) is simply the weight for a given height. Although it takes into account male and female genders but easy to look into through a simple chart. This is just a generalization that persons of the same height should have the same mass. This may create huge errors in standardising individual treatments.

 Predicted normal body weight (PBW) represents the expected normal weight of an obese individual as the sum of their lean body mass and their predicted normal fat mass, which excludes excess fat mass. This is a more reliable weight in standardising individual treatments. The formula for predicted body weight are

  • For females: PBW (kg) = 45.5 + 0.91 * (height [cm] - 152.4) 
  • For males: PBW (kg) = 50 + 0.91 * (height [cm] - 152.4)



1. NHLBI ARDS Network. Available at:

2. JJ MacDonald , J Moore , V Davey , S Pickering and T Dunne. The weight debate. Journal of the Intensive Care Society 2015, Vol. 16(3) 234–238 

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