Raised intracranial pressure

Raised ICP is a potentially life-threatening condition that can occur as a result of a brain injury or a wide range of health conditions. One of the symptoms of raised ICP is altered mental status. Changes in ICP can be caused by alterations in heart rate and blood volume due, for example, to haemorrhage or sepsis, or by cerebral trauma or neurological disease. These alterations disrupt the normal mechanisms that maintain ICP which, if not recognised and treated, can result in sustained raised ICP (Karakis et al 2017). Raised ICP affects blood flow to the cerebrum, causing hypoxia and increased levels of carbon dioxide, which in turn causes arteriolar dilation further increasing the ICP (Waugh and Grant 2014).

It is important that nurses have an understanding of the maintenance of ICP. This process can be explained by the Monro-Kellie hypothesis (Benson et al 2023), which is summarised as follows. The cranium is a rigid compartment containing non-compressible contents, including brain tissue, blood and cerebrospinal fluid. The volume of these three components is restricted by the fixed space in which they are contained, with the ICP being the pressure within the cranium. Cerebral perfusion pressure (CPP) (the pressure required to push blood through all of the vessels in the brain) is the difference between the mean arterial pressure (MAP) and the ICP (CPP=MAP-ICP) and must be maintained within a very narrow limit (Thomas et al 2015). Any alteration in ICP will affect the CPP, which then increases the risk of reduced perfusion to the brain tissue (Waugh and Grant 2014). Under normal circumstances, ICP is maintained by changes in intracranial blood volume and the pressure exerted by cerebrospinal fluid, which circulates around the brain and spinal cord. Normal ICP should be between 7 mmHg and 15mmHg in adults (Canac et al 2020).

The vasomotor centre in the medulla oblongata (comprising the lower section of the brainstem) maintains cerebral perfusion by regulating blood pressure, respiration and heart rate in response to the body’s status; however, if the ICP begins to rise due to brain injury for example, the medulla becomes compressed by the increasing pressure in the cranial space, resulting in cerebellum herniation through the foramen magnum (one of several openings at the base of the skull) into the upper spinal canal (Waugh and Grant 2014). Herniation of the cerebellum causes cardiorespiratory instability, with symptoms of hypertension, high pulse pressure, bradycardia, Cheyne-Stoke respirations (abnormal breathing pattern) and reduced level of consciousness. The combination of bradycardia and hypertension is known as Cushing Reflex, a late sign of raised ICP which is difficult to reverse (Waugh and Grant 2014).

Neurological assessment

In patients with altered mental status a neurological assessment should be completed using a validated tool to identify the extent of the alterations (NICE 2023, Royal College of Physicians and Surgeons of Glasgow 2023). For patients with acute and/or life-threatening injuries or conditions, the neurological assessment should form part of the ABCDE assessment and should not be undertaken in isolation (Resuscitation Council UK 2021). Additionally, the use of a ‘track-and-trigger’ tool, such as the National Early Warning Score (NEWS) 2 (Royal College of Physicians 2017), will support timely identification of deteriorating patients and prompt appropriate intervention. In the NEWS 2 tool, a score is allocated to vital signs already recorded in routine practice; a higher score means the parameter is further from the normal range, which triggers appropriate clinical interventions (Royal College of Physicians 2017).

Various factors may contribute to an alteration in a patient’s mental status, including: metabolic or systemic conditions; medicines or toxins; hospital-acquired factors; and primary neurologic conditions (Srikanth 2022). The patient’s past and current medical history can assist in identifying factors which may have contributed to their altered mental status (Srikanth 2022), therefore the nurse must take account of this information when undertaking a neurological assessment. Table 1 lists factors that may contribute to alteration in mental status and includes corresponding potential sources and/or causes.

Two neurological assessment tools commonly used in clinical practice are the AVPU (Alert, responds to Voice, Pain or Unresponsive) – or the more recent A(C)VPU – and the GCS. Alongside the use of these tools, nurses must undertake an assessment of the patient’s pupils for size and reaction (Carter and Notter 2023).

Alert, responds to Voice, Pain or Unresponsive assessment

The AVPU approach enables rapid assessment of a patient’s mental status, responsiveness or level of consciousness and requires no formal training (Royal College of Physicians 2012, Williams 2019). There is no numerical scoring for this tool and assessment is recorded as ‘responds to voice’ or ‘unresponsive’, for example.

The AVPU assessment tool was modified in the revised NEWS 2 to include ‘confusion’ (A(C)VPU) (Royal College of Physicians 2017) to enable identification of ‘new onset confusion’, which can be a sign of clinical deterioration in an otherwise alert patient. The assessment of new onset confusion can help to identify any deviation from the patient’s normal mental status. However, the Resuscitation Council UK (2021) guidelines on management of the deteriorating patient still refer only to the AVPU method. Nurses must therefore be alert to variations in local and national guidelines and training programmes.

If the nurse has any concerns about, or there are any changes in, the patient’s mental or neurological status, the nurse must escalate these concerns immediately to the nurse in charge and, if trained, undertake a comprehensive neurological assessment using the GCS.

Glasgow Coma Scale

The GCS was developed in the 1970s and is an internationally recognised and validated neurological assessment tool (Teasdale and Jennett 1974, Teasdale et al 2014, Royal College of Physicians and Surgeons of Glasgow 2023). The GCS has also been incorporated into national training courses, such as Resuscitation Council UK (2021) programmes. Clinicians, including nurses, must be trained to use the GCS to assess a patient’s level of consciousness and to compare their findings with previous assessments (Cook et al 2019).

The GCS uses a scoring system based on scores awarded for best eye opening, best verbal response and best motor response (Table 2), which, when added together, provide a total score of between three and 15 (Mehta and Chinthapalli 2019). The highest score of 15 indicates the patient is alert and oriented, while a score of three indicates deep unconsciousness. The GCS score must be documented on a GCS chart to enable recognition of improvement or deterioration based on previous assessments. Nurses should recognise that the score alone does not explain the cause of any changes in neurological status. For example, a total score of eight could be based on ‘eye opening=2, verbal=2 and motor=4’ or ‘eye opening=1, verbal=1 and motor=6’ – these parameters have very different implications for the severity of the patient’s condition and only become evident when charted (Royal College of Physicians and Surgeons of Glasgow 2023).

Pupil response

Pupil size and reaction to light are important components of a neurological assessment because they can indicate the quality of the patient’s third cranial nerve (oculomotor) function or a lack of function. Normal pupil size is 3-5mm and pupils constrict briskly in response to light. Before assessing the patient’s pupil response, the nurse must observe both pupils to check if they are of equal size, because some medicines such as atropine sulfate and some health conditions such as eye surgery can alter pupil size, shape and reaction (Waugh and Grant 2014).

Using a bright pen torch, the nurse should assess each pupil separately by shining the light from the side of the eye and observing the reaction of the pupil. It is crucial that the light is shone from the side of the eye because the pupil will constrict in response to an approaching object – termed the ‘accommodation response’ – which will affect the accuracy of the assessment (Waugh and Grant 2014).

Pupil size is recorded in millimetres (Figure 1). If the reaction is brisk, it is charted as positive (+); if it is slow or sluggish it is recorded with the letter ‘S’; if there is no reaction, or the pupil is fixed, it is recorded as negative (-). The neurological observation chart or the side of the pen torch may include an infographic showing a range of pupil sizes, similar to the image shown in Figure 1, to assist with the assessment.

Figure 1.

Pupil size scale

If a pupil is fixed, dilated and does not react to light this could indicate injury or pressure on one side of the brain and the patient will require an urgent neurological review (Carter and Notter 2023).

Frequency of neurological observations in patients with head injury

NICE (2023) guidelines on the assessment and early management of head injury recommend that any patient who presents to an emergency department with a head injury must be assessed within a maximum of 15 minutes of arrival. Those with impaired consciousness (GCS <15) must be assessed immediately and observations should be undertaken and recorded every 30 minutes until there is a GCS score of 15. Minimum frequency of observations for people with an initial GCS score of 15 should be half-hourly for two hours, then one hourly for four hours, then two hourly (NICE 2023).

Senior clinicians or medical staff may request neurological observations to be recorded every 15 minutes depending on the clinical situation (Derbyshire and Hill 2019), for example in patients with trauma, concussion or acute deterioration. In addition, patients with head injury should be reassessed urgently if any of the following signs of neurological deterioration are observed (NICE 2023):

A noted limitation of using the GCS is inter-observer reliability, which may result in over or underassessment, therefore NICE (2023) recommends that a second practitioner who is competent to undertake neurological observations should assess the patient before escalating any concerns. When handing over patients it is also good practice for the nurse going off shift to undertake a set of neurological observations with the nurse coming on shift so that they can compare findings and maintain consistency (NICE 2023).

Potential challenges in recording of neurological observations

Every effort must be made by nurses to maintain accuracy when undertaking and documenting patients’ neurological observations. However, while there are few studies on the accuracy of recording neurological observations, there is evidence of inaccurate recording of vital signs, incomplete neurological observations and failures in the early escalation of deteriorating patients (Downey et al 2017). NICE (2023) has identified strategies to improve neurological assessment, including training and education, use of standardised charts and use of NEWS 2.

To try to address issues related to inadequate recording of neurological and other observations and failure to escalate deteriorating patients, some organisations use electronic documentation systems. Such systems have been shown to support consistency and accuracy of recording vital signs by prompting the healthcare professional to undertake a full set of vital signs, which are automatically calculated and, in some instances, referred on to the appropriate clinical team (Vincent et al 2018, Watson and Carberry 2021). The use of an electronic documentation system may assist in the identification of missing vital signs and prompt nurses to undertake the relevant observations, which could reduce the risk of lost data and improve nurses’ adherence (Watson and Carberry 2021). However, the lack of availability of computers in some clinical areas may limit the effectiveness of this approach and conversely increase the risk of missed or delayed recording of vital signs, in turn delaying the recognition of a deteriorating patient (Watson and Carberry 2021).

Another potential challenge with regards to recording neurological observations is nurse staffing levels. For example, an observational study of nurses and nursing assistants on surgical and acute general wards in England found that late or missed vital signs were frequent, but that higher nurse staffing levels resulted in a lower rate of missed or delayed vital sign recording (Redfern et al 2019). The nurse staffing crisis in the UK may therefore adversely affect the monitoring of patients at risk of deterioration (Mitchell 2022, Royal College of Nursing 2022). Nurses must recognise the importance of prioritising patients who require neurological observations. If care for these patients is delegated to a junior colleague or nursing student, supervision and monitoring of their practice is essential.

Conclusion

The ability to undertake an effective neurological assessment is an essential skill for nurses in all areas of practice, because patients may develop altered mental status in response to acute neurological insults as well as a range of other health conditions and comorbidities. It is vital that nurses respond quickly to symptoms of altered mental status by undertaking an appropriate neurological assessment, documenting the findings accurately and escalating the patient as appropriate. Early escalation promotes prompt intervention and treatment, which is essential to prevent patient deterioration. All clinicians, including nurses, must be trained to use the GCS to assess a patient’s level of consciousness and to compare the findings with previous assessments.