Brain Multimodality Monitoring: A New Tool in Neurocritical Care of Comatose Patients
Table 1
Multimodality parameters: commonly used measurement devices, physiologic ranges, threshold at which early goal therapy should be considered, and clinical significance.
Modality
Means of monitoring
Physiologic range
Threshold
Clinical significance
Intracranial pressure
(1) Intraparenchymal monitor
<20 mmHg
>20–25 mmHg
Marker of cerebral edema and impending herniation.
(2) Intraventricular monitor (EVD)
Cerebral perfusion pressure
60–70 mmHg
<60 mmHg
Indirect surrogate of CBF. Guide treatment of intracranial hypertension to optimize perfusion.
Cerebral blood flow
(1) TCD
Mean flow velocities
MCA mean flow velocity >200 cm/s
Detection of vasospasm and delayed cerebral ischemia in SAH.
MCA 30–75 cm/s
ACA 20–75 cm/s
PCA 15–55 cm/s
LR < 3
LR > 6
Differentiate hyperemia from vasospasm.
(2) TDP
50 mL/100 g/min
<20 mL/100 g/min
Indicative of regional cerebral ischemia.
Cerebral oxygenation
(1) Juglar venous oximetry
50–80%
<50% or >80%
Indicative of global ischemia or hyperemia and tissue extraction of oxygen.
(2) Licox™
35–40 mmHg
<20 mmHg
Indicative of regional hypoxia/hypoperfusion.
Cerebral metabolism
Microdialysis
Glucose 0.4–4.0 μmol/L
<0.4
Indicative of brain energy supply and demand.
Lactate 0.7–3.0 μmol/L
>3.0
Pyruvate unknown Lactate to pyruvate ratio <20
>40
Elevated LPR indicative of ischemia, anaerobic metabolism.
Glutamate 2–10 μmol/L
>10
Increased glutamate and lactate earliest marker of ischemia followed by increased glycerol.
