What is subsegmental atelactasis ?

This describes: A small area of lung that is not completely inflated. It is benign and causes are many, including not taking a deep breath during the exam.

Partial collapse : Sub segmental collapse or atelectasis has many etiologies including mucus plugging from asthma, enlarged heart can compress bronchi, hypoventilation, anesthesia, ct exams, sometimes aspiration, etc. Mostly transient and disappearing with deeper inspiration.