Effects of Iloprost on Arterial Oxygenation and Lung Mechanics during One-Lung Ventilation in Supine-Positioned Patients: A Randomized Controlled Study

Abstract

Patients undergoing one-lung ventilation (OLV) in the supine position face an increased risk of intraoperative hypoxia compared with those in the lateral decubitus position. We hypothesized that iloprost (ILO) inhalation improves arterial oxygenation and lung mechanics. Sixty-four patients were enrolled and allocated to either the ILO or control group (n = 32 each), to whom ILO or normal saline was administered. The partial pressure of the arterial oxygen/fraction of inspired oxygen (PaO2/FiO2) ratio, dynamic compliance, alveolar dead space, and hemodynamic variables were assessed 20 min after anesthesia induction with both lungs ventilated (T1) and 20 min after drug nebulization in OLV (T2). A linear mixed model adjusted for group and time was used to analyze repeated variables. While the alveolar dead space remained unchanged in the ILO group, it increased at T2 in the control group (n = 30 each) (p = 0.002). No significant differences were observed in the heart rate, mean blood pressure, PaO2/FiO2 ratio, or dynamic compliance in either group. Selective ILO nebulization was inadequate to enhance oxygenation parameters during OLV in the supine position. However, it favorably affected alveolar ventilation during OLV in supine-positioned patients without adverse hemodynamic effects.

Cutting-Edge Approaches in Respiratory and Critical Care Medicine

“…Most importantly, they identified for the first time the existence of another circulatory volume, the rest volume (Vr), that seems to have dual main functions in the steady state, i.e., to prevent an increase in venous resistance and maintain critical closing pressure. The maintenance of Vr may be a key factor for the cardiovascular stability reported during selective iloprost nebulization by Lee et al [ 29 ], suggesting that Vr may have a key role in the prevention of V/Q mismatch. These conditions are important for maintaining (or improving) hemodynamic coherence, i.e., the translation of macrohemodynamics to effective cellular oxygenation, and thus a low endothelial inflammatory status.…”