These results indicate that minimal VD/VT can be used for PEEP titration in ARDS.Īcute respiratory distress syndrome (ARDS) is a In addition, a significant change of dynamic tidal respiratory compliance and oxygenation index was induced by PEEP titration. During the Po period, VD/VT decreased to a lower value (0.44☐.08) compared with that during the injury period (0.68☐.10) (P<0.05), while the intrapulmonary shunt fraction reached its lowest value. The optimal PEEP in this study was found to be 13.25☑.36 cm H2O. Respiration and hemodynamic parameters were recorded during the periods of pre‑injury and injury, and at 4 and 2 cm H2O below and above the optimal PEEP (Po).

The optimal PEEP was identified by the lowest VD/VT method. VD/VT was measured using single‑breath analysis of CO2, and calculated from arterial CO2 partial pressure (PaCO2) and mixed expired CO2 (PeCO2) using the following formula: VD/VT = (PaCO2 ‑ PeCO2)/PaCO2. The PEEP was reduced by 2 cm H2O every 10 min until 0 cm H2O was reached, and VD/VT was measured after each decrement step. A lung recruitment maneuver was then conducted and the PEEP was set at 20 cm H2O. Twelve swine models of ARDS were constructed. This study aimed to apply the dead space fraction to titrate the optimal positive end-expiratory pressure (PEEP) in a swine model of acute respiratory distress syndrome (ARDS).

Intrapulmonary shunting vs dead space