Effect of β₂-adrenergic receptor stimulation on lung fluid in stable heart failure patients

Background The purpose of this study was to determine: (1) whether stable heart failure patients with reduced ejection fraction (HFrEF) have elevated extravascular lung water (EVLW) when compared with healthy control subjects; and (2) the effect of acute β₂-adrenergic receptor (β₂AR) agonist inhalation on lung fluid balance. Methods Twenty-two stable HFrEF patients and 18 age- and gender-matched healthy subjects were studied. Lung diffusing capacity for carbon monoxide (DLCO), alveolar–capillary membrane conductance (Dm_CO), pulmonary capillary blood volume (V_c) (via re-breathe) and lung tissue volume (V_tis) (via computed tomography) were assessed before and within 30 minutes after administration of nebulized albuterol. EVLW was derived as V_tis – V_c. Results Before administration of albuterol, V_tis and EVLW were higher in HFrEF vs control (998 ± 200 vs 884 ± 123 ml, p = 0.041; and 943 ± 202 vs 802 ± 133 ml, p = 0.015, respectively). Albuterol decreased V_tis and EVLW in HFrEF patients (–4.6 ± 7.8%, p = 0.010; –4.6 ± 8.8%, p = 0.018) and control subjects (–2.8 ± 4.9%, p = 0.029; –3.0 ± 5.7%, p = 0.045). There was an inverse relationship between pre-albuterol values and pre- to post-albuterol change for EVLW (r² = –0.264, p = 0.015) and Dm_CO (r² = −0.343, p = 0.004) in HFrEF only. Conclusion Lung fluid is elevated in stable HFrEF patients relative to healthy subjects. Stimulation of β₂ARs may cause fluid removal in HFrEF, especially in patients with greater evidence of increased lung water at baseline.