Reversible restrictive lung disease stimulating asthma.

A young adult woman presented with spontaneous and exercise-induced episodic dyspnea without wheezing. During dyspneic episodes all static lung volumes decreased markedly, the inspiratory capacity fell from 3.0 to 1.1 litres and total lung capacity from 5.3 to 2.6 litres. Airway resistance (Raw) remained normal, and maximal expiratory flows at low absolute lung volume actually increased. Static compliance decreased from 0.153 to 0.077 litre/cmH2O, and the elastic recoil increased from 2.8 to 4.8 cmH2O at 50% of baseline total lung capacity when dyspneic. Upstream airway resistance (Rus) remained unchanged, 1.7 cmH2O/litre/sec. All physiologic variables indicated a reversible restrictive process exists, the origin of which is unclear. It is concluded that the episodic increase in elastic recoil properties results in [1] loss of volume primarily in the alveolar ducts and sacs, [2] preservation of normal Rus by an increase in driving pressure, and [3] maintenance of normal Raw by stabilization of larger airways.