Hyperventilation in Patients With Traumatic Brain Injury

Study Overview
=================
Brief Summary
-----------------
Elevated intracranial pressure is a dangerous and potentially fatal complication after traumatic brain injury. Hyperventilation is a medical intervention to reduce elevated intracranial pressure by inducing cerebral vasoconstriction, which might be associated to cerebral ischemia and hypoxia. The main hypothesis is that a moderate degree of hyperventilation is sufficient to reduce the intracranial pressure without inducing cerebral ischemia.

Detailed Description
-----------------
In patients with severe traumatic brain injury (TBI), and with intracranial pressure-monitoring, brain tissue oxygen tension and/or microdialysis probes hyperventilation-tests are performed in the acute phase after trauma. Data are collected and TCCD measurements are performed at baseline, at the beginning of moderate hyperventilation, after prolonged moderate hyperventilation (for 50 minutes) and after return to baseline. The present study aims to quantify potential adverse effects of moderate short-term hyperventilation during the acute phase of the severe TBI on cerebral hemodynamics, oxygenation, and metabolism.

Official Title
-----------------
Effects of Moderate Hyperventilation on Cerebral Hemodynamics, Oxygenation and Metabolism in Patients With Severe Traumatic Brain Injury

Conditions
-----------------
Head Injury Trauma, Hyperventilation

Intervention / Treatment
-----------------
* Other: Hyperventilation test


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: nonpenetrating traumatic brain injury Glasgow coma scale <9 at presentation Intracranial pressure monitoring brain tissue oxygen tension monitoring and/or microdialysis monitoring invasive mechanical ventilation with FIO2 <60% and PEEP <15 mbar Exclusion Criteria: decompressive craniectomy pregnancy pre-existing neurological disease previous traumatic brain injury acute cardiovascular disease severe respiratory failure acute on chronic liver disease sepsis failure to obtain satisfactory bilateral TCCD signals persisting hypovolemia or hemodynamic instability

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Interventional Model Description: several parameters are collected at different time points: at baseline conditions, during moderate hyperventilation, and after return to baseline
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: patients with severe TBI<br>Patients with severe TBI enrolled in the study undergo an hyperventilation test, in which the alveolar ventilation is increased by a stepwise increase in tidal volumes and respiratory rate until a reduction of etCO2 of 0.7 kPa is achieved. | Other: Hyperventilation test<br>* Increase of the alveolar ventilation by a stepwise increase in tidal volumes and respiratory rate until a reduction of end-tidal CO2 of 0.7 kPa is achieved<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| intracranial pressure | Change of intracranial pressure during moderate hyperventilation | 10, 20, 50, 60 minutes after begin of the hyperventilation test | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| cerebral flow velocity in the middle cerebral artery | Change of cerebral flow velocity during moderate hyperventilation | 20, 50, 60 minutes after begin of the hyperventilation test | 
| brain tissue oxygenation (PbrO2) | no changes | 10, 20, 50, 60 minutes after begin of the hyperventilation test | 
| cerebral Lactate/ Pyruvate ratio | no changes | 1 hour before initiation of the hyperventilation test, and 1 and 2 hours after begin of the hyperventilation test | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
cerebral metabolism, intracranial pressure, cerebral oxygenation