The effect of β2 adrenergic‐receptor stimulation on lung fluid balance in heart failure

Abstract

BackgroundIncreased pulmonary capillary pressure and a possible desensitization of lung β2 adrenergic receptors (β2AR) involved in fluid removal mechanisms may increase extravascular lung water (ELW) in stable heart failure (HF) patients. Whether these patients exhibit increased ELW remains controversial.PurposeTo determine if HF patients have elevated ELW versus controls (CTL) and if acute β2AR agonist inhalation stimulates fluid removal.Methods/Results14 stable HF patients and 19 healthy age/gender matched CTL were studied. Lung tissue volume (Vtis) (includes tissue, blood and water) and pulmonary capillary blood volume (Vc) were assessed pre and post nebulized albuterol via CT and rebreathe, respectively. ELW was derived as Vtis – Vc. Pre albuterol, ELW was greater in HF vs. CTL (861±241 vs. 739±143 ml, P<0.01), with no difference in Vtis (938±246 vs. 830±151 ml, P=0.08). Albuterol decreased Vtis (–4±2%, P=0.02) but did not change ELW (739±143 vs. 724±132 ml) (P>0.05) in CTL. In HF, albuterol decreased both Vtis (–5±3%) and ELW (– 4±2%) (P<0.05). There was a negative relationship between baseline values and the pre to post albuterol change for Vtis (r2=0.38) and ELW (r2=0.42) (P<0.01) in HF.ConclusionLung fluid is elevated in stable HF patients relative to healthy subjects. Stimulation of β2ARs appears to enhance fluid removal in HF, especially in patients with elevated lung water at rest.