Traumatic head Injury is the most common cause of death and disability in the UK (National Institute of Clinical Excellence (NICE), 2014) and is the world’s leading cause of morbidity and mortality of those under the age of 45 (Wilson, 2011). A head injury has an impact in epidemiological and economic terms as well as loss in quality of life (Mar et al. 2011). Approximately 700,000 people per year in England and Wales attend an emergency department for head injury, with almost half being the result of falls (NICE, 2007 & Clinical Knowledge Summary, 2009). The vast majority of patients (90%) will have minor head injuries (Vos et al. 2012) and be discharged, however many patients will ...view middle of the document...
The brain can be divided into three areas; the hindbrain (cerebellum), the midbrain (pons varolii, medulla oblongata and brain stem) and the forebrain (Cerebrum) (Porth, 2011). Within the brain there is a ventricular system containing four connected cavities which contain cerebrospinal fluid (CSF). The CSF is a clear fluid of water, protein, oxygen, carbon dioxide, sodium, potassium, chloride and glucose, (Dolan & Holt, 2013) that enables the brain to float within the cavity of the bony structure of the rigid skull. Between the skull and the brain there are three membranes; dura, arachnoid and pia mater collectively known as meninges, which also provide protection and cushioning of the brain (Porth, 2011).
The brain has high energy requirements and in normal conditions, mostly provided by adenosine triphosphate (ATP) from the circulation (Belanger et al. 2011). ATP is produced by the metabolic degradation and oxidative phosphorylation of glucose (Hall et al. 2012). Oxygen is required via the cerebral circulation to facilitate this metabolism. Depletion of ATP causes neuron depolarisation which in turn leads to failure of membrane ion-transport systems (Guyton, 2010). Although the brain makes up only 2% of the body’s weight, about 20% of the oxygen and 25% of the glucose consumed by the body are dedicated to cerebral functions (Porth, 2011 & Belanger et al. 2011).
The brain occupies about 80% of the space within the cranial cavity, the remaining 20% being occupied by cerebrospinal fluid (CSF) and blood, occupying 10% each. The volume of these contributes to the Intracranial Pressure (ICP) which is normally maintained within a range of 0 to 15mmHg (Porth, 2011). ICP represents the pressure exerted by the CSF within the ventricles of the brain (Hickey, 2009). If the volume of one component increases, the other two components can compensate by displacement of CSF from the intracranial compartment to the spinal subarachnoid space, increased rate of CSF absorption and reduction of cerebral blood volume by displacement of venous cerebral blood into the venous sinuses, without causing changes in the ICP. This is known as Monro-Kellie hypothesis (Porth, 2011).
Severe head injury can affect the compensatory mechanisms resulting in them becoming rapidly exhausted (Deitch & Dayal, 2006) and failing.
If Sam was showing symptoms such as confusion, memory loss and reduced ability to move his body this would be indicative of cerebral hypoxia, which could be a result of ICP increasing above 20 mmHg (Brain Trauma Foundation, 2007). If ICP increases and unrelieved, compression of the brainstem could occur, causing Sam to become bradycardia, hypertensive and have a decreased respiratory rate, known as the Cushing’s response.
The brain is dependent on blood flow to provide oxygen and nutrients to the neurones and remove waste products. The cerebral blood flow (CBF) is generally constant 700ml/min, approximately...