Hemodynamic Monitoring in ARDS: What to Know in 2018

Abstract

Approximately, two-third of patients with acute respiratory distress syndrome (ARDS) have hemodynamic instability and require vasopressors. Under mechanical ventilation, decreased preload of the right ventricle (VD) due to increased pleural pressure (P_PL) and increased post-VD secondary to increased transpulmonary pressure (P_TP) will be aggravated by ARDS. The consequences will be a decrease in overall cardiac output and a risk of progression to the acute cor pulmonale (ACP). Monitoring driving pressure, positive expiratory pressure, and control hypoxemia and hypercapnia will have both respiratory and hemodynamic impact. Echocardiography plays a central role in hemodynamic monitoring during ARDS, through assessment of cardiac output, different intracardiac filling pressures and the diagnosis of ACP. Pulmonary arterial catheter is an entire monitoring method, and is indicated in cases of right ventricular failure or severe pulmonary arterial hypertension; but the risk of adverse effects is high. Transpulmonary thermodilution (TPTD) monitors allow real-time cardiac output monitoring and are valuable in assessing the volume status. The evaluation of the preload dependence should not be carried out on the respiratory variabilities of the pulsed pressure or the diameter of the vena cava, but through the passive leg raising test, the tele-expiratory occlusion test, or the titration tests.