Automation of Protective Ventilation in Acute Lung Injury

Abstract

Mechanical ventilation with positive pressure is the supportive therapy for patients with acute lung failure. To minimize pulmonary stress by prevention of end-expiratory alveolar collapse and over-distension of pulmonary areas, lung protective ventilation strategy has become standard therapy. Low tidal volume ventilation (V_T ≤ 6ml, per kg predicated body weight) proved to reduce mortality rates in patients with lung failure notably. Recent surveys on intensive care units showed that the transfer of this evidence-based knowledge to ventilation therapy has not been realized in the current care of ventilated patients. Automated execution of protective ventilation protocols would help to optimize the individual setting in mechanical ventilated patients. To test the ability to automate protective ventilation protocols, the adjustment of positive pressure ventilation was realized in a saline lavage induced lung injury study in pigs. The implemented controllers were programmed to meet the therapeutic goals (tidal volume, oxygenation, plateau pressure, pH, inspiratory to expiratory ratio) of the ARDSnet-protocol. During the trial, all measurements were made using an online blood gas monitor (TrendCare Satellite, Diametrics Medical Inc., England), a monitor for hemodynamic parameters (Sirecust 1281, Siemens, Germany), a capnograph (CO2SMO+, Respironics, Inc., USA), and an electrical impedance tomography (EIT) prototype system (EIT evaluation Kit, Draeger Medical, Germany). After successful automated therapy, PaCO2 and FiO2 levels could be significantly reduced. Thus, the execution of automated protective ventilation protocols with an electronically controlled ventilator was possible and led to pulmonary stabilization in saline lavage induced acute lung injury.