TABLE 1.

The impact of obesity on parameters of respiratory physiology

Parameter	Effect
Expiratory reserve volume	Reduction
Functional residual capacity	Reduction
Total lung capacity	Reduction (only in the morbidly obese)
Vital capacity/forced vital capacity	Mild reduction
Forced expiratory volume in 1 s	Mild reduction
Maximal expiratory flow at 25–75% of forced vital capacity	Reduction
Diffusion capacity	Reduction/no change/increase
Respiratory muscle strength	No change
Respiratory muscle endurance	Reduction
Airway resistance	Increase
Airway reactance	Increase
Neural respiratory drive	Increase