Acute brain injury due to aneurysmal subarachnoid haemorrhage (SAH) or traumatic brain injury (TBI) is a condition with a high mortality, and surviving patients often have permanent disabilities. Multimodal neuromonitoring of intracranial pressure, brain tissue oxygen tension (PbtO2), and brain energy metabolism (measured with microdialysis (MD)) may help individualise the treatment of this patient group to protect the brain and potentially improve outcomes. However, there is still a significant lack of knowledge regarding the advantages and disadvantages of this type of monitoring. The present study consists of four substudies with the overall aim of examining which factors are most influential for regulating commonly measured intracerebral parameters such as oxygenation, glucose, and lactate. Additionally, the influence of these of parameters on functional outcome and mortality will be explored. The individual studies are detailed below:
Substudy 1: This study investigates the relationship between glucose in blood and microdialysate (MD-glucose) in patients with severe traumatic brain injury (TBI) or aneurysmal subarachnoid haemorrhage (SAH). Substudy 2: The aim of this substudy is to examine the contribution of arterial oxygen tension (PaO2) to PbtO2 in patients with acute brain injury. We hypothesize that there is an association between the two parameters, that this relationship is altered in patients with concurrent intracranial hypoertension, and that a higher burden of cerebral hypoxia is associated with poor functional outcome and mortality. Substudy 3: The study aims to estimate the contribution of systemic lactate to microdialysate lactate, hypothesizing that: 1. PbtO2 and cerebral perfusion pressure are independent predictors of microdialysate lactate in patients with cerebral hypoxia (PbtO2\<20). 2. Systemic lactate is an independent predictor of microdialysis lactate in patients without cerebral hypoxia. Substudy 4: The study aims to establish whether there is a predictive threshold value of MD-glutamate for unfavourable functional outcome 6 months after ictus of brain injury. Additionally, we aim to explore whether there is a pattern of MD-glutamate that can predict episodes of neuroworsening.
Study Type
OBSERVATIONAL
Enrollment
200
Rigshospitalet
Copenhagen, Denmark
Correlation between systemic glucose and microdialysis glucose
Median goodness of fit (Pearsons R2)
Time frame: Throughout the duration of neuromonitoring in the neuro-ICU (1-30 days)
Median goodness of fit (Pearsons R2) of the relationship between PaO2 (kPa) and PbtO2 (mmHg).
Median goodness of fit (Pearsons R2)
Time frame: Throughout the duration of neuromonitoring in the neuro-ICU (1-30 days)
Correlation between systemic lactate and microdialysis lactate when corrected for PbtO2 and cerebral perfusion pressure.
Median goodness of fit (Pearsons R2)
Time frame: Throughout the duration of neuromonitoring in the neuro-ICU (1-30 days)
The predictive value of glutamate measured by intracerebral microdialysis for episodes of neuroworsening
Area under the curve
Time frame: Throughout the duration of neuromonitoring in the neuro-ICU (1-30 days)
The predictive value of glutamate measured by intracerebral microdialysis for 6-month functional outcome
Modified Rankin Scale
Time frame: Throughout the duration of neuromonitoring in the neuro-ICU (1-30 days)
Length of hospital stay
Time in days
Time frame: From admission until discharge (1-300 days)
Mixed effects linear regression of the relationship betwen PaO2 (kPa) and PbtO2 (mmHg).
mmHg/kPa
Time frame: Six months after admission to the neuro-ICU
Functional outcome at six months
Modified Rankin Scale
Time frame: Six months after admission to the neuro-ICU
Mortality at six months
Percent
Time frame: Six months after admission to the neuro-ICU
Length of stay in the ICU
Time in days
Time frame: From admission until discharge from the ICU (1-300 days)
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