The Cerebral-Respiratory Interaction in Controlled Mechanically Ventilated Neurosurgical Patients. (The CeRes-CMV Study)

The Effects of Airway Closure, Expiratory Flow Limitation and of a Passive Chest Wall on the Onset of an Uncontrolled Expiration and on Intracranial Pressure. An Observational Clinical Study on Neurosurgical Patients. (The CeRes-CMV Study)

The impact of mechanical ventilation on intracranial perfusion is still not completely clarified. It is often assumed that raising airway pressure will invariably elevate the intracranial pressure, but this is not always the case.

The effects of airway pressure on intracranial pressure can depend on several factors, and among others, an uncontrolled expiration and consequent lung collapse may have an influence on cerebral perfusion.

This study will investigate the incidence and the consequences of an uncontrolled expiration and expiratory lung collapse in critically ill neurosurgical patients during controlled mechanical ventilation.

Electrical impedance tomography measurements , oesophagus and gastric pressure, electrical activity of the diaphragm and intracranial pressure will be acquired in a synchronised manner during controlled mechanical ventilation. Moreover, airway opening pressure, expiratory flow limitation and recruitment/inflation ratio will be determined during controlled mechanical ventilation, on a daily bases until the patient recover his/her own spontaneous breathing.

The patients will be included within 48 hours from initiation of mechanical ventilation and insertion of an external ventricular drainage catheter

Inclusion Criteria:

• Age >18 years;
• MV expected for more than 72 hours;
• Not pregnant;
• Informed consent from patient or next of kin.

Exclusion Criteria:

• Previously demonstrated paralysis of the diaphragm or know pathology of the phrenic nerve or neuromuscular disorder,
• Chest tube,
• Patients with clinical conditions that contraindicate the insertion of esophageal/gastric catheters (e.g., esophagus rupture, esophageal bleeding),
• Pacemaker and/or implantable cardioverter defibrillator, these last being a contraindication for EIT.
• Hemicraniectomy. In case of late hemicraniectomy (after patient inclusion), the patient will drop-out from the study.

Relative contraindication: in case of skull base fracture the patient can be included only if oesophageal/gastric and NAVA catheters can be inserted orally.