An obstructive disease will show increased FRC because some airways do not empty normally, while a restrictive disease will show decreased FRC . Body plethysmography is particularly appropriate for patients who have air spaces which do not communicate with the bronchial tree; in such patients helium dilution would give an incorrectly low reading.
22.
In " State of North Carolina v . Spencer ", the court reviewed the literature and case law and concluded that penile plethysmography was scientifically unreliable : " Despite the sophistication of the current equipment technology, a question remains whether the information emitted is a valid and reliable means of assessing sexual preference ."
23.
They concluded, " Until a way can be devised to detect and / or control false negatives and false positives, the validity of the test data will be questionable . " Hall and Crowther noted penile plethysmography " may be even more problematic than other [ methods ] in assessing susceptibility of the test to faking ."
24.
Freund was initially commissioned to use penile plethysmography to detect recruits attempting to evade military service by falsely claiming to be homosexual . ( The Czechoslovak Army barred homosexuals from serving . ) His larger research program, however, focused on detection and diagnosis of sex offenders, particularly preference pedophiles, with a view to more appropriate treatment guidelines.
25.
Due to the high variable course of disease, the higher incidence of complications such as lung cancer ( up to 25 % of patients has been reported in IPF ) a routine evaluation every 3 to 6 months, including spirometry ( body plethysmography ), diffusion capacity testing, chest X-rays, 6MWT, assessment of dyspnea, quality of life, oxygen requirement is mandatory.
