Cardiovascular Effects of a Nebulized B‐agonist Compared to Saline in Healthy Humans

Abstract

The β2‐adrenergic receptors (ADRB2s) are located in the heart and blood vessels. We sought to determine the influence of an inhaled β‐agonist on cardiac output (Q), heart rate (HR), stroke volume (SV), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and systemic vascular resistance (SVR) in healthy subjects (n=17, age=27±9years, ht=170±8cm, wt=68±12kg, Vo2Peak=98±27% predicted, mean±SD). To determine this, we assessed cardiovascular function before and 30, 60, and 90 minutes following the administration of a β‐agonist (2.5 mg albuterol in 3ml saline) or placebo (saline). Inhalation of saline resulted in no change in any of the measured or calculated cardiovascular parameters. Albuterol resulted in an increase in Q and SV, no change in HR or BP, and a drop in SVR (Q=3.6±1.0, 4.2±1.1, 4.4±1.3, and 4.3±1.1 liters/min.; HR=77±9, 80±10, 78±9, and 78±11 beats/min.; SV=46±12, 51±15, 56±14, 56±13ml/beat; SBP=106±12, 105±13, 107±10, and 108±10mmHg; DBP=69±8, 66±8, 69±8, and 68±9mmHg; MAP=80±11, 79±8, 81±7, and 81±9mmHg; SVR=1661±453, 1401±432, 1393±424, and 1384±391 dynes*sec/cm5, mean±SD, for baseline, 30, 60, and 90min post β‐agonist, p‐ANOVA<0.05 for Q, SV and SVR). These results demonstrate that the administration of a nebulized β‐agonist results in enhanced ventricular function and a drop in systemic vascular resistance, suggesting peripheral vasodilation.