Head injuries and raised intracranial pressure Chapter 25

Remember Airway – ET intubation CPP – Maintain MAP Prevent secondary brain injury Triad of head, facial and neck injuries

Signs and symptoms of raised intracranial pressure Early Late Thus hypovolaemic shock may be masked by cerebral ischaemia reflex

Treatment of high intracranial pressure Remove space-occupying lesions – Not you Drain CSF – Not you Decrease intracranial blood volume – You Prevent arterial vasodilatation Ventilation Decrease oxygen consumption Prevent venous congestion Prevent Brain Oedema – You CPP Fluids

Cerebral Perfusion Pressure CPP CPP = MAP – ICP Cerebral outoregulation blunted CPP = 60 TO 70 mmHg Bedside – For each 10 cm vertical elevation of the head (ear) above the heart (middle of upper arm) , the cerebral perfusion pressure decreases by about 7 mmHg

CPP Increasing MAP , Decreasing VP Decrease brain volume Oedema Ventricular drain Decrease Oxygen consumption Induced/permissive hypothermia Sodium thiopental Systemic homeostasis BP Adrenaline Dobutamine Phenylephrine

CPP Systemic homeostasis Diabetes insipidus Cerebral salt wasting Diuresis, hypernatraemia, low urine osmol Cerebral salt wasting Diuresis, hyponatraemia, high urine osmol Coagulation Temperature Cardiac manifestations

Fluid therapy Avoid hypotonic fluids Maintain normal to high plasma osmolality Hyperglycemia worsens TBI Glucose containing fluids contraindicated Treat hyperglycemia Brain oxygenation Hct 30 , Cardiac output , Oxygen

Treatment of brain oedema Glucocorticoids Infection and tumours Osmotic agents Mannitol

Anaesthetic management Other injuries RSI Ketamine Suxamethonium Low normal CO2 , 35 mmHg Intubation response Positioning NB!!!!!

Anaesthetic management Positioning 15 degrees Not anti-trendellenburg Head neutral position No hyperextension No rotation

Anaesthetic management Mayfield head clamp Air embolism CPP Avoid N2O , Vapour MAC < 1 Muscle relaxation Fluids ECG neurogenic changes

Anaesthetic management Hyponatreamia ADH oliguria Cerebral salt wasting Diuresis Diabetes Insipidus Hypernatreamia, diuresis, low urine osmol Extubation