Abstract
Introduction: It has been suggested that dynamic arterial elastance (Ea(dyn)) can predict decreases in arterial pressure in response to changing norepinephrine levels. The objective of this study was to determine whether Ea(dyn) is correlated with determinants of the vascular waterfall [critical closing pressure (CCP) and systemic arterial resistance (SARi)] in patients treated with norepinephrine. Materials and Methods: Patients treated with norepinephrine for vasoplegia following cardiac surgery were studied. Vascular and flow parameters were recorded immediately before the norepinephrine infusion and then again once hemodynamic parameters had been stable for 15 min. The primary outcomes were Ea(dyn) and its associations with CCP and SARi. The secondary outcomes were the associations between Ea(dyn) and vascular/flow parameters. Results: At baseline, all patients were hypotensive with Ea(dyn) of 0.93 [0.47;1.27]. Norepinephrine increased the arterial blood pressure, cardiac index, CCP, total peripheral resistance (TPRi), arterial elastance, and ventricular elastance and decreased Ea(dyn) [0.40 (0.30;0.60)] and SARi. Ea(dyn) was significantly associated with arterial compliance (C-A), CCP, and TPRi (p < 0.05). Conclusion: In patients with vasoplegic syndrome, Ea(dyn) was correlated with determinants of the vascular waterfall. Ea(dyn) is an easy-to-read functional index of arterial load that can be used to assess the patient's macro/microcirculatory status.