Tony Figaji MBChB, MMed, FCS, PhD Head of Pediatric Neurosurgery Red Cross Children’s Hospital University of Cape Town

Neurocritical care is underdeveloped Pediatric neurocritical care is even worse Secondary brain injury is underappreciated

The brain is complex Children are physiologically different Individual and temporal heterogeneity Many different causes for raised ICP, standard Rx Surrogate markers of brain health used Direct measures of brain physiology?

 Brain tissue oxygen tension  Near-infrared spectroscopy  Jugular venous saturation  Continuous EEG  Microdialysis  TCD / autoregulation  Continuous CBF  Physiological imaging

1. Classic cellular oedema 2. Hyperemia 3. Vasospasm 4. Subclinical seizures 5. Impaired autoregulation GCS 4 ICP = 35 GCS 4 ICP = 35 GCS 4 ICP = 35 GCS 4 ICP = 35 GCS 4 ICP = 35 BrO2 low CBF↓/N BrO2 high, FV / CBF high BrO2 low, FV high/ LR↑ BrO2 low, EEG typical BrO2 passive, ARI low

Examined associations with outcome in multivariate model: clinical, physiological, radiological Adjusted Odds Ratio for poor outcome: PbtO2 2 hoursOR 10.8 ( ) PbtO2 1 hourOR 27.4 ( ) Strongest independent predictor of outcome Mortality for series = 9.6% Low BrO2 is associated with poor outcome Childs Nerv Syst Oct;25(10):1325-3

It is not a surrogate marker of something else It is not predicted by measures of initial injury severity

% of pts Brain hypoxia/ischemia is common despite observing current thresholds for treatment based on available evidence Figaji et al, Neurosurgery Jul;63(1):83-91

BrO2 ICP

N=75 children 9452 hrs monitoring

ICP PbtO2 MAP

BrO2 decompressive craniectomy Can evaluate the effects of intervention Figaji et al, Acta Neurochir Suppl. 2008;102:77-80

ICP PbtO2 MAP ICM+ Increase in blood pressure Pressure autoregulation, intracranial pressure and brain tissue oxygenation in children with severe traumatic brain injury Figaji et al. J Neurosurg Peds, 2009;4:420-8

PbtO 2 : 28.7 ± 6.8 mmHg CPP :64 ± 15 mmHg FiO 2 : 46 ± 12% PbtO 2 : 33.3 ± 11.8 mmHg CPP :70 ± 13 mmHg FiO 2 : 47 ± 13% P=0.002 P=0.021 P= Account for CPP change: Co-efficient , P= hour period post-RBCTBaseline values The effect of blood transfusion on brain oxygenation in children with severe traumatic brain injury Figaji et al. Pediatric Crit Care Med 2009 Blood transfusion

ICP PbtO2 ↑FiO2 ↓FiO2 Increase in PaO2

 34 patients, 291 TCD studies  Mean Flow Velocity (MCA): 95 (79-115) range cm/s Figaji et al, Surgical Neurology 2009; 72: Patients are different

 Yes  No Depends on correct application and interpretation Intervention misapplied can have equally hazardous effects The treatment may be worse than the problem Gives us more information Lets us know when patients are getting into trouble before an established problem Helps interpret the underlying pathophysiological problem Helps us titrate therapy appropriately Probably reduces secondary injury