Pulmonary blood volume measured by 82Rb-PET in patients with chronic obstructive pulmonary disease: a retrospective cohort study.

Abstract

In patients with chronic obstructive pulmonary disease (COPD), pulmonary vascular dysfunction and destruction are observable before the onset of detectable emphysema, but it is unknown whether this is associated with central hypovolemia. We investigated if COPD patients have reduced pulmonary blood volume (PBV) evaluated by 82Rb-positron emission tomography(PET) at rest and during adenosine-induced hyperemia. This single-center retrospective cohort study assessed 6301 82Rb-PET myocardial perfusion imaging (MPI) examinations performed over a 6-year period. We compared 77 COPD patients with 44 healthy kidney donors (controls). Cardiac output (Q̇) and mean 82Rb bolus transit time (MBTT) were used to calculate PBV. Q̇ was similar at rest (COPD: 3649 ± 120 mL vs. control: 3891 ± 160 mL, p=0.368) but lower in COPD patients compared to controls during adenosine infusion (COPD: 5432 ± 124 mL vs. control: 6185 ± 161 mL, p < 0.050). MBTT was shorter in COPD patients compared to controls at rest (COPD: 8.7 ± 0.28 seconds vs. control: 11.4 ± 0.37 seconds, p < 0.001) and during adenosine infusion (COPD: 9.2 ± 0.28 seconds vs. control: 10.2 ± 0.37 seconds, p < 0.014). PBV was lower in COPD patients, even after adjustment for body surface area, sex, and age at rest (COPD: 530 (29) mL vs. 708 (38) mL, p < 0.001) and during adenosine infusion (COPD: 826 (29) mL vs. 1044 (38) mL, p<0.001). In conclusion, patients with COPD show evidence of central hypovolemia, but it remains to be determined whether this has any diagnostic or prognostic impact.