The effects of vasopressor and vasodilator on hemodynamic energy in terms of surplus hemodynamic energy

In a previous study, we reported that inotropic agents affect the hemodynamic energy, which can be measured using the energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE). However, there has been no study about the effect of vasopressors and vasodilators on EEP and SHE. Thus, we investigated the change in the hemodynamic energy induced by phenylephrine, nitroprusside, norepinephrine, and milrinone in terms of the EEP and SHE. Phenylephrine (1, 3 μg/kg/min), nitroprusside (0.5, 1 μg/kg/min), norepinephrine (0.1, 0.25 μg/kg/min), and milrinone (bolus 50 μg/kg, followed by 0.5, 0.7 μg/kg/min) were infused into 13 anesthetized dogs. The hemodynamic parameters, mean arterial pressure (MAP), and flow were recorded in the descending thoracic aorta, and EEP and SHE were calculated. MAP, EEP, and SHE increased significantly with phenylephrine administration. However, the flow in the descending aorta decreased significantly (p < 0.05). Norepinehrine also significantly increased MAP, EEP, and SHE (p < 0.05 in all cases). The MAP, EEP, and SHE significantly decreased after nitroprusside infusion (p < 0.05), whereas milrinone did not have an effect on MAP, EEP, or SHE. In conclusion, vasopressors were found to increase EEP and SHE, while a vasodilator decreased EEP and SHE.