Conditions: Emphysema
Allocation: NON_RANDOMIZED | Intervention model: SINGLE_GROUP
Enrollment: 22
Healthy volunteers: yes

Brief summary:
The purpose of this study is to determine if the events leading to smoking-associated centrilobular and paraseptal emphysema are caused by a failure of the lungs' inherent mechanisms to block hypoxic pulmonary vasoconstriction (HPV) in areas of smoking-induced inflammation.

Detailed description:
Overall goals of this study are to 1) determine the effects on sildenafil on the heterogeneity perfused blood volume in smokers susceptible to emphysema using dual energy CT 2) utilize pulmonary blood volume heterogeneity as an image-based biomarker to differentiate normal and susceptible smokers.

Arms:
arm 1: 8 subjects recruited to study non-contrast imaging at TLC and 20%VC and with contrast using DECT to assess perfused blood volume. For the intervention, the subject will be administered 20 mg of Sildenafil and then the same scanning will be repeated one hour after sildenafil administration. arm 2: 11 subjects recruited to study non-contrast imaging at TLC and 20% VC and with contrast using DECT to assess pefused blood volume. For the intervention the subject will be administered 20 mg of Sildenafil and then the same scanning will be repeated one hour after sildenafil administration.

Interventions: intervention 1: Sildenafil study group
Intervention descriptions: intervention 1: One dose of 20 mg Sildenafil will be given one hour before CT imaging.

Protocol document: