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

Study Overview
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Brief Summary
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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.

Official Title
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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)

Conditions
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Mechanical Ventilation Complication, Neurological Disorder, Lung Injury

Intervention / Treatment
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* Other: Mechanically ventilated neurosurgical patients


Participation Criteria
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Eligibility Criteria
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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.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Mechanically ventilated neurosurgical patients<br>Observational study in mechanically ventilated neurosurgical patients | Other: Mechanically ventilated neurosurgical patients<br>* Observational study where respiratory variables and intracranial pressure will be measured during mechanical ventilation and during specific respiratory manoeuvres. No intervention is planned.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The incidence of lung collapse | The incidence of an uncontrolled expiration and consequent expiratory lung collapse (determined by expiratory flow limitation, airway opening pressure and expiratory thoracic impedance) increased chest-wall elastance in neurosurgical patients. | during the period of controlled mechanical ventilation, an average of 14 days | 
| Correlation between lung recruitability and intracerebral pressure | The influence of lung recruitability (determined by recruitment/inflation ratio and changes of thoracic impedance) on intra cerebral pressure in neurosurgical patients. | during the period of controlled mechanical ventilation, an average of 14 days | 
| Correlation between lung collapse and intracerebral pressure | The correlation between an uncontrolled expiration (determined by expiratory flow limitation, airway opening and expiratory thoracic impedance), increased chest-wall elastance and intracranial pressure in neurosurgical patients. | during the period of controlled mechanical ventilation, an average of 14 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intensive care unit (ICU) and hospital length of stay (LOS); | Correlation between lung collapse and LOS | At ICU/hospital discharge, an average of 30 days | 
| Number of days of mechanical ventilation | Correlation between lung collapse and days of mechanical ventilation | At ICU discharge, an average of 20 days | 
| 90-days mortality from intensive care unit admission | Correlation between lung collapse and 90-days mortality | 90 days after hospital discharge | 
| 30-day and 90-days neurological and functional outcomes | Correlation between lung collapse and 30-day and 90-days neurological and functional outcomes (Disability Rating Scale, clinical frailty score, Glasgow Outcome Scale) | 90 days after hospital discharge |