Introduction: There are many variables that are associated with outcome for patients who have suffered a severe head injury. Intracranial pressure and cerebral perfusion pressure may be the most significant predictors of outcome. There are little published data on the relationship between these two pressure measurements in paediatric cases and the difficulty in analysis is compounded by variation in their normal distribution that occurs with age. This study examines the paediatric patients who have suffered a head injury with the aim of identifying age related thresholds of ICP and CPP.
Methods: A total of 200 head-injured children (16 years or under) admitted to hospital in Edinburgh, London, Newcastle and Southampton, who had ICP monitoring as part of their routine management were studied. Mean ICP and CPP over the first 6 h of monitoring were evaluated. Patients included if they were over the age of 2 and had a minimum of 6 h of monitoring. Independent outcomes (good recovery and moderate disability) were compared against poor outcomes (severe disability and death) in different age groups. There were no vegetative survivors.
Results: The group consisted of 126 boys and 74 girls; 88 made a good recovery, 53 a moderate disability (141 independent outcome), 28 remained severely disabled and 31 died (59 poor outcomes). There was a significant difference between the independent and poor survivors in relation to ICP and CPP (p50.001). Patients were divided into three groups according to age; G1 aged 2 - 6 (n=49), G2 aged 7 - 10 (n = 66) and G3 aged 11 - 16 (n = 85). Receiver Operator Characteristic curves demonstrated a different relationship between ICP and CPP with outcome for the different groups. The sensitivity of both ICP and CPP was similar in all age groups. The specificity of both CPP and ICP differed between each group. For ICP, a 50% specificity occurred 24, 19 and 18 mmHg for groups G1, G2 & G3, respectively. For CPP the same level of specificity occurred at 53, 58 and 67 mmHg.
Discussion: There is little difference in the sensitivity of either ICP or CPP in relation to outcome in this paediatric head injury group. However, differences in specificity for both ICP and CPP between the old age group were noted. At a value of 50 mmHg the specificity of CPP varied considerably between the groups (G1 =0.47, G2 =0.22, G3 = 0.14) suggesting that younger children may be able to tolerate lower levels of CPP and still have an independent outcome. A larger series of patients may help in more closely defining these levels, particularly in relation to age. This is important in the identification of those patients that might benefit from the intervention of a new treatment (e.g. decompression) as a therapy of potential benefit.
Chambers IR, Kirkham F, Jones PA, Minns RA, Stobbart L, Mendelow AD. ICP, CPP and outcome in paediatric head injury. British Journal of Neurosurgery, October 2003; 17(5): 478-479.
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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