Lerner M A
Clin Radiol. 1978 Mar;29(2):155-9. doi: 10.1016/s0009-9260(78)80221-9.
In lateral recumbency the uppermost lung is in a state of relative inspiratory apnoae. This physiological phenomenon may be exploited to obtain inspiratory chest films in children and uncooperative adults and as an improvement on the sitting film of patients unable to stand. It also tests to some extent the pulmonary compliance and the mobility of the diaphragm.