Pressure-controlled Versus Volume-controlled Ventilation During Protective One Lung Ventilation

Pressure-controlled Versus Volume-controlled Ventilation During Protective One Lung Ventilation for Thoracic Surgery

The aim of this study is to determine the effects of pressure controlled ventilation during protective one lung ventilation on blood gases, airway pressures and hemodynamic variables compared with volume controlled ventilation.

One-lung ventilation (OLV) during thoracic surgery, in particular, video-assisted thoracic surgery is a standard practice to facilitate surgical exposure, but arterial hypoxemia has been a serious complication during one lung ventilation. Furthermore, recent studies have shown that one lung ventilation with a conventional tidal volume can involve lung injury associated with alveolar overdistension and high airway pressure. Therefore, lung protective ventilation with a low tidal volume during one lung ventilation has been suggested, and a recent study showed that protective ventilation during lung cancer surgery was associated with improved postoperative respiratory outcomes such as reduced incidence of acute lung injury and atelectasis.

During protective one lung ventilation limiting airway pressure and using low tidal volume, it is important to provide uniform alveolar expansion and maintain adequate oxygenation. A previous study suggested that the decelerating inspiratory flow delivery used in pressure controlled ventilation improved ventilation/perfusion distribution and arterial oxygenation during one lung ventilation5. Moreover, according to a recent study during laparoscopic obesity surgery, pressure-controlled ventilation improved oxygenation compared with volume controlled ventilation, which was associated with higher instantaneous flow peaks and a better alveolar recruitment6. On the other hand, other studies showed that ventilatory mode during one lung ventilation did not affect arterial oxygenation. However, these studies were performed during mechanical ventilation using conventional tidal volume, and the effect of ventilatory mode during protective one lung ventilation on oxygenation has not been clearly determined yet.The aim of this study is to determine the effects of pressure controlled ventilation during protective one lung ventilation on blood gases, airway pressures and hemodynamic variables compared with volume controlled ventilation.

Inclusion Criteria:

• patients (ASA physical status I-III) undergoing elective thoracic surgery in the lateral position with at least 1 h of one lung ventilation

Exclusion Criteria:

• patients with major organ dysfunction, hemodynamic instability, or increased intracranial pressure