Objectives: To determine age related thresholds of CPP in relationship to outcome in paediatric head injury using an integrated time/value technique.
Methods: Sixty-six head injured children (age ≤16) from two regional centres who had minute-by-minute recordings of physiological variables within 24 hours of injury were studied. Previously determined levels of derangement for three age bands were used (table 1) and the area between these and the CPP curve calculated. This cumulative pressure-time (CPT) index provided an age related measure that is associated to both severity and length of derangement. These thresholds were then reduced by 10% and 20% to determine whether they might differentiate outcome.
Results: There was a significant difference between the area product and outcome (six month GOS) at each of the three threshold levels (p<0.001). The mean value of CPT for independent outcome was 3228 (95% CI 1557, 4898) and for poor outcome 32713 (95% CI 16168, 49258). ROC curves demonstrated that the initial thresholds were the best predictors of outcome.
Age |
Mean CPP threshold |
|---|---|
| 2-6 years | ≤48 mmHg |
| 7-10 years | ≤54 mmHg |
| 11-16 years | ≤58 mmHg |
CPT = ∑(CPPthreshold-CPP) x tsampleinterval
Discussion: This technique shows promise as a pressure-time weighted index to assist in the separation of good/poor outcomes. Age related thresholds have been used to calculate insult severity by incorporation of depth and duration of CPP derangements. A 90% specificity was achieved at a level of 9829 mmHg minutes and a 75% sensitivity at a level of 1746 mmHg minutes. It is important to use age related thresholds in paediatric cases as they demonstrably change as children develop.
Jones PA, Chambers IR, Andrews PJ, Chaudhry W, Clark A, Croft J, Forsyth R, Fulton B, Lo TYM, Mendelow AD, Wilson G and Minns RA. Quantification of secondary CPP insult severity in paediatric head injured patients using a pressure-time index. Oral presentation at the 12th International symposium on Intracranial Pressure and Brain Monitoring. Hong Kong 16-26th August 2004.
Dr. Iain R. Chambers, Cleveland Unit, Middlesbrough. Tel: +44 (0)1642-854-778.
Regional Medical Physics Department, Freeman Hospital, Newcastle upon Tyne, NE7 7DN, UK.
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