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