BACKGROUND Acute respiratory distress syndrome (ARDS) is described as the most common non-neurologic organ dysfunction occurring in the early phase after severe acute brain injury, with a reported incidence of 10-15% and increased morbidity and mortality.
A significant role has been recently proposed for neuro-inflammation in the genesis of ARDS following acute brain injury. The neuro-inflammatory response represents initially a coordinated effort to protect the brain after injury, but may then become altered and be responsible for the activation of the secondary injury cascade leading to single or multiple organ dysfunction. This preclinical event may increase the susceptibility of lungs to the stress of injurious mechanical ventilation. The main targets of ventilatory management of acute brain injury patients are maintenance of an optimal oxygenation, and a tight arterial carbon dioxide control. Actual Guidelines for the management of severe traumatic brain injury, in particular, state that hypoxia (PaO2 \<60 mmHg or SaO2 \< 90%) should be avoided and PaCO2 level tightly controlled with a target of 35-38 mmHg. However, no published recommendation exists on which ventilator setting, in terms of tidal volume, respiratory rate, and positive end-expiratory pressure (PEEP) levels, should be used to obtain these respiratory targets. In previous studies on patients with ARDS, mechanical ventilation with a low tidal volume and moderate PEEP levels resulted in decreased mortality and increased number of ventilatory free days, and it now represents the standard of care for these patients.
Patients with acute brain injury represent a category at risk to develop ARDS both because of the adrenergic cascade and the inflammatory reaction, and because of the ventilatory strategy implemented to optimize gas exchange. Nevertheless, no clinical trial has been performed to evaluate the effect of protective ventilatory strategies upon severe acute brain injury patients.
AIMS The aim of this study is to investigate whether the application of a protective ventilatory strategy, defined as low tidal volume and moderate levels of PEEP, improves the combined end point of "event free survival" defined as survival without ventilator dependency or ARDS diagnosis, without adversely affecting neurological outcome.
Secondary aim of this study is to evaluate if protective ventilatory strategy may increase number of ventilator and organ failure free days, reduce intensive care unit (ICU) length of stay, reduce the incidence of ventilator associated pneumonia (VAP), reduce concentrations of plasma inflammatory cytokines (IL-6, TNF-alpha, TNF-RI/II, IL-8, IL-1ra, IL-1beta), without adversely affecting neurological outcome as measured by the Modified Oxford Handicap scale at intensive care unit discharge and the Glasgow Outcome Scale-extended (GOSe) at 6 months.
