Children

The management of raised ICP in childhood must take account of a number of factors.4,171 The critical values for ICP, arterial pressure, and cerebral perfusion pressure are lower the younger the child. The normal intracranial pressure in the newborn is probably of the order of 2-4 mmHg. Arterial pressure at birth is approximately 55/40 mmHg, 80/55 mmHg by one year, and 90/60 mmHg during the early school years. Cerebral perfusion pressure rises from 28 mmHg at 28-32 weeks of gestational age to 38 mmHg at normal full term. In the neonate, much lower cerebral blood flow values may be tolerated for longer. Many of the pathologies differ from the adult, including birth asphyxia, posthaemorrhagic ventricular dilatation, craniocerebral disproportion, and the many metabolic and infective encephalopathies. The skull may expand due to high ICP in children where fusion of the sutures has not occurred. Hyperaemia plays a greater role as a cause of raised ICP in children after head injury than in adults.172,173 The NIH Traumatic Data Bank of severe head injuries revealed that diffuse brain swelling occurs twice as often in children (aged 16 years or younger) as in adults. A total of 53% of children with diffuse swelling died compared with a mortality rate of 16% in those without. It has recently been suggested that ICP should be treated above a threshold of 15 mmHg in infants, 18 mmHg in children younger than eight years, and 20 mmHg in older children and teenagers.174 In a retrospective study it has been shown that overall outcome is better when cerebral perfusion pressure is kept above 40 mmHg.175 In another study analysing data from 24 children with a mean age of 63 years, all survivors had had a cerebral perfusion pressure of 50 mmHg or higher.176 Based on these studies a recent review has suggested that cerebral perfusion pressure should be maintained above 40-45 mmHg in infants and young children and above 50-55 mmHg in older children and adolescents.174 Seizures are more frequent in head-injured children than in adults.177 Early seizures may occur in up to a third of the patients.178 Children with non-accidental injury ("shaken baby syndrome") suffer from very severe injury with poor prognosis and a high morbidity in survivors.178 Controlled trials of therapy in the various conditions are made difficult by the very small numbers of patients seen in each centre. As with adults, there is a wide diversity of opinion on the use of barbiturate coma, steroids, and mannitol. Mannitol induced hyperosmolarity greater than 320 mosm/L seems to be well tolerated in children.174

Management of raised intracranial pressure - conclusions Conscious patient

• Diagnosis based on suspicious history (novel headaches, nausea, vomiting, visual blurring/obscurations, diplopia) with or without papilloedema on examination

Any patient with drowsiness or fluctuation in level of consciousness or visual obscurations merits emergency referral to neurosurgery

• Definitive investigation by CT scan combined with general medical assessment including chest radiograph

Never perform a lumbar puncture in a patient with suspected raised ICP, even if papilloedema is absent, until a CT scan has shown no evidence of either a mass lesion or diffuse brain swelling

• Management depends on the presumptive diagnosis after CT and proceeds in consultation with neurosurgery; for example, space occupying lesion:

- tumours: dexamethasone, tissue diagnosis and excision, radiotherapy, chemotherapy as appropriate

- abscess: aspiration/excision

• Hydrocephalus: CSF shunt with or without prior ICP monitoring/ CSF infusion studies

• Benign intracranial hypertension: referral to combined neurosurgery/neuro-ophthalmology service for CSF monitoring, diuretics/steroids/diet for mild cases. CSF shunt/optic nerve sheath fenestration for severe/refractory cases

Unconscious patient where intracranial catastrophe suspected (for causes see Box 7.1)

Emergency resuscitation for patients no longer obeying commands

• Intubation and ventilation

• Intravenous mannitol (0-2 ml/kg) when patient deteriorating

• Definitive investigation:

- CT scan in combination with general medical assessment and consideration of any available history

- intracranial pressure monitoring

Management of raised intracranial pressure

• Institute specific treatment for aetiology (Box 7.1)

- "lumpectomy"

- aspiration of cysts/abscesses

• Hydrocephalus: external ventricular drainage:

- establish CSF drainage if possible even where no hydrocephalus despite technical difficulties

• Cerebral oedema and brain swelling:

- dexamethasone for tumours only, not for trauma

- occasionally abscesses

• Maintain cerebral perfusion pressure >70 mmHg

• Maintain intracranial pressure < 25 mmHg:

- avoid problems exacerbating raised intracranial pressure (Box 7.4)

- nurse at 30 degrees head up

- sedation, analgesic, neuromuscular blockade

- optimal ventilation (Paco2 4-5-4-0 kPa)

- check for positive end expiratory pressure/venous obstruction

- treat seizure activity vigorously

- mild hypothermia

- boluses of 20% mannitol 2 ml/kg (to plasma osmolality of 310 mmol/L)

- consider intravenous anaesthetic to reduce cerebral metabolic rate of oxygen, such as propofol 2-5 mg/kg per hour

- consider surgical decompression (remove bone flap/ contused temporal or frontal lobe)

• Ensure adequate mean arterial pressure:

- adequate hydration

- avoid excessive sedation

- optimal volume status (right arterial pressure/pulmonary capillary wedge pressure monitoring)

- consider vasoactive agents (norepinephrine, dopamine, or phenylephrine)

• Does the patient need rescanning? Reaccumulation of clot/ hydrocephalus

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