restrictive disorder?

Question

why is it that those with restrictive disease can exhale 80% or more of FVC even though their FVC is reduced? and for those with obstructive pulmonary disease they exhale less than 80%? Thanks.

Answer 1

Restrictive disorder prevents the lungs from expanding fully, thus a decrease in lung volumes identified by the forced FVC but there is no obstruction to airflow. Therefore, FEV1 and other parameters of flow remain relatively normal thus enabling to exhale the 80% or more of FVC .

While in Obstructive Disorder, airways are narrowed and resistance to flow is high. There is usually air trapping, therefore not so much air can be expelled (less than 80% of FVC) while residual volume increases.FEV1 will be also decreased because the amount of air originally inhaled is low, not because of airway resistance.

Answer 2

restrictive lung disease doesn't impair exhalation because there's no obstructive disease. it just causes restriction (as the name implies) so all the lung volumes are decreased- FVC, TV, TLV- they're all decreased. so the ratio of the FEV1/FVC is unchanged.