The Effects of Inverse Ratio Ventilation with PEEP on Respiratory Function and Inflammatory Cytokines in Patients during One-lung Ventilation

Abstract

Background: Hypoxemia is the most common complication during one-lung ventilation (OLV). Inverse ratio ventilation (IRV) may lead to intrinsic positive end-expiratory pressure (PEEP) and improve oxygenation in acute respiratory distress syndrome, so we investigated whether volume-controlled IRV with external PEEP could improve hypoxemia, reduce the risk of acute lung injury during OLV. Methods: Sixty patients undergoing one-lung ventilation for open thoracoctomy were randomly divided into IRV group and control group (n = 30). All patients were initially ventilated with a tidal volume of 8 mL/kg, an inspiratory: expiratory (I:E) ratio of 1:2 and a respiratory rate of 12 breaths/min in 100% oxygen without PEEP. During OLV, lungs were ventilated either with I:E of 2:1 (IRV group) or 1:2 (control group) with an actual tidal volume (VT) 7 mL/kg, respiratory rate 12 breaths/min, external PEEP of 5 cm H2O. Arterial blood was collected respectively to analyze blood gas before and during OLV. Meanwhile, hemodynamic and respiratory mechanics were monitored. The concentrations of IL-1β, IL-6 and IL-8 in bronchoalveolar lavage fluid (BALF) were measured before and during OLV. Results: Compared to the control group, partial pressure of arterial oxygen (PaO2 ), mean airway pressure and dynamic compliance (CL) were significantly higher in IRV group during OLV (P < 0.05). However, plateau pressure (Pplat) and levels of IL-1β, IL-6 and IL-8 in BALF were lower in IRV group than those in control group (P < 0.05). Conclusion: IRV (I:E = 2:1) applying PEEP could improve hypoxemia, promote oxygenation, and improve dynamic compliance of respiratory system, moreover reduce Pplat and the release of inflammatory cytokines in patients during one-lung ventilation. It is superior to conventional ventilation with PEEP during one-lung ventilation.