Sources of information: Serial Glasgow Coma Scale or sedation score ratings over 24 hours, as well as readily available input from the patient’s bedside critical care nurse or family. Feature 2. Inattention

• Did the patient have difficulty focusing attention?
  
• Is there a reduced ability to maintain and shift attention?

• Was the patient’s thinking disorganised or incoherent, such as rambling or irrelevant conversation, unclear or illogical flow of ideas, or unpredictable switching from subject to subject?
  
• Was the patient able to follow questions and commands throughout the assessment?

• Any level of consciousness other than ‘alert’.
  
• Alert – normal, spontaneously fully aware of environment and interacts appropriately
  
• Vigilant – hyperalert
  
• Lethargic – drowsy but easily aroused, unaware of some elements in the environment, or not spontaneously interacting appropriately with the interviewer; becomes fully aware and appropriately interactive when prodded minimally
  
• Stupor – difficult to arouse, unaware of some or all elements in the environment, or not spontaneously interacting with the interviewer; becomes incompletely aware and inappropriately interactive when prodded strongly
  
• Coma – unarousable, unaware of all elements in the environment, with no spontaneous interaction or awareness of the interviewer, so that the interview is difficult or impossible even with maximal prodding

Chevrolet and Jolliet (2007) caution that the CAM-ICU may have sacrificed a degree of sensitivity and specificity for speed and ease of use, but a number of studies have subsequently demonstrated that this tool has reasonable validity, with satisfactory sensitivity and specificity. It is relatively fast and easy to use and is also classed as reliable with good inter-rater reliability (Ely et al. 2001). Despite the positive influence of the CAM-ICU tool, the presence of delirium is frequently missed as nurses often fail to diagnose it in their patients (Inouye et al. 2001). Nelson (2009) provides a useful and more detailed overview of the CAM-ICU tool and how to ensure it is used effectively.

Alternatively, the Intensive Care Delirium Screening Check List (ICDSC) devised by Bergeron et al. (2001) could be used to assess the ICU patient. This uses an 8-point score with each item scored as present or absent (0 or 1), a score of 4 or more defining delirium. This tool is not, however, suitable for comatose or stuporous patients (Morandi et al. 2009).

The CAM-ICU is recommended for use by NICE (2010) and would be an appropriate assessment instrument for Harry.

Related pathophysiology

The precise mechanisms by which patients like Harry develop delirium are not clear, except where there is an obvious metabolic disorder such as hypoglycaemia (Chevrolet and Jolliet 2007). A number of theories have been postulated as to the cause of delirium and its possible long-term effects (Pandharipande et al. 2005; Morandi et al. 2009). Patients with delirium have abnormal brain scans, with evidence of hypoperfusion, and in some, cerebral atrophy is evident (Morandi et al. 2009). The brain abnormalities seen on neuroimaging of these patients points to a diffuse rather than a localised event, which is likely to be a result of global falls in cerebral blood flow. The cerebral hypoxia may be proportional to the severity of illness and be a consequence of responses to sepsis or other physiological insults (Chevrolet and Jolliet 2007; Morandi et al. 2009). The exact relationship between agitation, delirium and cerebral dysfunction remain poorly understood. It is not clear, for example, whether the brain is the passive victim of the physiological insult, along with many organs that dysfunction in critical illness, expressing its injury through agitation and delirium, or if it is the active player, participating and contributing to the extracerebral organ dysfunction (Chevrolet and Jolliet 2007).

Sepsis and the inflammatory and coagulation responses that ensue in this condition have a recognised association with the development of delirium, as the rates are much higher in these patients (Pandharipande et al. 2005; Morandi et al. 2009). The damage caused during sepsis may be related to the presence of large quantities of cytokines. Substances such as interleukin-1 and tumour necrosis factor cause endothelial damage and coagulopathy, and may alter the structure of the blood-brain barrier, resulting in a reduction of synaptic transmission and neuronal excitability (Morandi et al. 2009).

Delirium may also be related to imbalances in the synthesis, release and inactivation of neurotransmitters that are important in the regulation of cognitive function, behaviour and mood (Pandharipande et al. 2005). Three of the neurotransmitter systems involved in the pathophysiology of delirium are dopamine, g-aminobutyric acid (GABA) and acetylcholine. Dopamine increases the excitability of neurons, whereas GABA and acetylcholine decrease neuronal excitability. Imbalances in these neurotransmitters result in neuronal instability and unpredictable neurotransmission (Pandharipande et al. 2005). It is widely believed in delirium that there is an excess of dopamine and depletion of acetylcholine and this may be due to the effects of anticholinergic agents on brain function. Many drugs, likely to have been administered to Harry during his critical care stay, have anticholinergic properties, for example, antiarrhythmics and antibiotics, and these may cause an imbalance of dopaminergic and cholinergic neurotransmission.

A recent study by Pandharipande et al. (2008) examined the relationship between sedative drugs and GABA neurotransmission. GABA is an important inhibitory neurotransmitter but many of the sedative drugs, such as the benzodiazepines (lorazepam, midazolam) and propofol, commonly used in the ICU, have a high affinity for GABA receptors and may inhibit GABA neurotransmission leading to delirium. Pandharipande et al. (2008), in their study, found an association with both lorazepam and midazolam with delirium but not with propofol, fentanyl or morphine. This may have implications for the prescription and use of sedative agents (see Chapter 11 on care of the patient requiring sedation).

There does not appear to be, from the current data, a uniform or single causative agent for the development of delirium in the critically ill, or at least not one that is yet known. Further research is needed to establish stronger associations and provide evidence that might lead to effective prevention. It is likely, however, that delirium is multi-factorial in most patients. Many probably develop delirium from a combination of severe illness, sepsis, metabolic disturbances, coagulopathy, cerebral hypoxia or impaired neurotransmission as a result of drug or sedative therapy. Others may develop delirium from a single mechanism.

Risk factors

Risk factors for delirium can be divided into those that predispose the patient to delirium and those that may precipitate it (Arend and Christensen 2009; Morandi et al. 2009). Predisposing factors include older age (>65 years), lifestyle factors such as smoking and alcohol use and sensory impairments such as poor vision or hearing. There are a number of factors that may precipitate delirium: prolonged pain, the use of restraints, sedative drugs, sepsis, abnormal biochemistry and sleep deprivation (Chevrolet and Jolliet 2007; Pfister et al. 2008; Morandi et al. 2009) (see Table 13.2. for further factors causing distress in the critically ill).

Table 13.2 Factors that contribute to critically ill patients developing physical and emotional distress.

Source: Data extracted from Roundtable Meeting (2002, Fig. 2).

Gustafson et al. (1991, cited in Webb et al. (2000) also identified hypoxia and a perioperative fall in blood pressure as major contributing factors in the surgical patient. Tune et al. and others have implicated not only obvious anticholinergic drugs but also many other commonly used drugs with anticholinergic side effects as causes of delirium (Tune et al. 1993, cited in Webb et al. 2000).

The ability to prevent delirium by recognition of predisposing factors and early structured interventions is yet to be established for the ICU patient (Morandi et al. 2009). Findings from studies on elderly patients, however, may provide useful evidence of preventative measures through controlling risk factors with structured interventions. Inouye et al. (1999) saw a reduction in delirium incidence from 15% to 9.9% with additional reduction in length of delirium in patients who were targeted for a protocol-based interventions targeted at six risk factors: cognitive impairment; sleep deprivation; immobilisation; psychoactive medications; visual or hearing impairment and dehydration. Many of these factors are common to patients like Harry and it would seem logical, therefore, that a similar approach might be effective in critically ill patients.

NICE (2010), in their guidance for managing delirium, highlight the importance of controlling risk factors and both NICE (2010) and Morandi et al. (2009) suggest using a multi-component intervention strategy aimed at achieving this. Morandi et al. (2009) suggest adapting a four-step nurse-led protocol originally developed for the acute setting by Bergmann et al. (2005), cited in Morandi et al. (2009):

Harry has a number of risk factors for delirium such as his age (76 years), significant sedative use whilst he was intubated and ventilated, infection and episodes of hypoxaemia, and he may well have various abnormal biochemistry results during his ICU admission. Nurses caring for Harry should have had a high suspicion and be alert to the possible development of delirium in this patient. They should also have taken a patient history to ascertain if Harry has any history of confusional episodes, the presence of any neurological or psychiatric conditions or any history of substance misuse, smoking and alcoholism (Webb et al. 2000; Chevrolet and Jolliet 2007).

Managing the patient with delirium

Interventions for Harry are discussed below and these should be aimed at limiting the current and potential risk of further episodes of delirium, limiting the negative physiological and emotional effects of delirium for Harry and reorientation to his environment (NICE 2010).

Airway/breathing

Harry’s airway is currently patent but monitoring of his level of consciousness is ongoing to observe any potential airway compromise. Harry is self-ventilating and requires 40% oxygen. As he is agitated and picking at his lines, he may remove his mask and consequently be at risk of hypoxaemia, which could contribute to increased confusion and agitation and if sustained would prolong his delirium. Care should be taken to ensure that Harry receives adequate oxygen therapy and delivery via a nasal cannula might be more appropriate; although this will not guarantee a fixed oxygen percentage, Harry may be less inclined to remove this and may receive a more consistent gas delivery (O’Driscoll et al. 2008). His oxygen saturation should be monitored and oxygen titrated to maintain SpO2 >94%.

Harry should be assisted to sit in an upright position and, if safe to do so, should be assisted to sit out in a chair for intervals during the day. This will improve basal oxygenation and improve alveolar gas diffusion, decreasing Harry’s work of breathing and assisting in the prevention of hypoxaemia.

Circulation

Harry’s heart is in normal sinus rhythm and his blood pressure is within acceptable limits. He should continue to have regular cardiovascular assessment to ensure maintenance of an adequate circulation. Any disturbances in cardiac rate or rhythm or a fall in blood pressure should be managed accordingly.

In relation to delirium, NICE (2010) and Morandi et al. (2009) both stress the importance of avoiding dehydration and electrolyte disturbances as these factors are significant predisposing factors for delirium. Oral fluid intake should be attempted and regular offers of preferred drinks for Harry are important in assisting him to normalise and begin activities of self-care. Assistance with oral intake can also be undertaken by family members and allows them an opportunity to perform care for their loved one. Harry should be carefully observed to avoid potentially harmful spillages of hot or cold liquids. It is unlikely at this time that Harry will maintain a sufficient oral intake and so may require additional intravenous fluid therapy; an appropriate crystalloid solution should be prescribed and delivered.

A daily blood test for urea and electrolytes should be performed and replacement of abnormal levels undertaken, as hyponatraemia, hypocalcaemia and hypomagnesaemia may influence delirium (Chevrolet and Jolliet 2007; Morandi et al. 2009). (Fluid therapy is discussed in more detail in Chapters 3 and 4.)

As infection is also a precipitating risk for delirium, Harry should have assessment of his temperature to detect early any new infectious episodes. Any evidence of clinically significant fever (T ≥ 38.3°C) should prompt a septic screen (see Chapter 3) and treatment with antibiotic therapy (Department of Health (DH) 2007).

Disability of the central nervous system

Harry should have ongoing assessment of his neurological status using standard Glasgow Coma Score (GCS) assessment and delirium assessment with the CAM-ICU (NICE 2010).

Where possible, non-pharmacological management of Harry’s delirium should be attempted (NICE 2010). A priority of care for Harry is in measures to assist him to orientate and engage in his surroundings (NICE 2010; Morandi et al. 2009). Harry should not be given large amounts of information at any one time but should be told appropriate information regarding his condition and treatment (Headway 2007). It would be advisable, at this stage, not to present Harry with too many alternatives to choose from and the use of closed questions to obtain essential information might be helpful (Pfaff 2006).

Harry, his family and friends should be kept apprised of his condition and his family should be encouraged to visit. They should be given information about delirium and offered reassurance that Harry’s condition is not uncommon and that it can be treated (NICE 2010). They should also be advised to report to the staff any changes they note in Harry’s behaviour. Family and friends may help by orientating the patient to place and time, and be always mindful that such prompting should not be excessive as this might exacerbate the patient’s agitation (Pfaff 2006).

It is important that family, friends and staff do not take any physical or verbal abuse from Harry personally because he is reacting to his own perception of the environment, which includes those individuals present at that moment. If appropriate, the best approach might be to ignore abusive behaviour by walking away and returning when he appears less agitated, as reasoning or arguing with an agitated patient can be unproductive. If necessary it would be advisable to follow procedures for de-escalation and management of violence (NICE 2005).

Nurses should also ensure that Harry is provided with adequate sleep and rest. There is an association between sleep disruption delirium and systemic illnesses and mortality (Patel et al. 2008). Existing data demonstrate that sleep is commonly disrupted in critically ill patients, but data on the consequences of sleep disruption and deprivation on actual health outcomes are lacking (Bijwadia and Ejaz 2009). Sleep is thought to be an important precipitating factor in delirium (Morandi et al. 2009). Lack of sleep may cause activation of the stress response leading to raised blood glucose levels, and increased metabolic and oxygen requirements. It may increase the patient’s risk of infection or lead to disordered thinking, confusion and agitation and is known to be a precipitating factor in the development of delirium.

The critical care environment is known to cause significant physiological and psychological discomforts for patients. The majority of patients, when asked, complain of lack of sleep with frequent disruptions and awakenings (Freise 2008; Patel et al. 2008; Bijwadia and Ejaz 2009). In fact many patients probably achieve average hours of sleep (7–9 hours) but this is mainly daytime sleep in short periods that does not allow for deeper, more satisfying REM sleep (Bijwadia and Ejaz 2009). Critical care areas are busy with activity occurring at any time of the day or night. Noise levels can be high due to alarms, staff conversations, equipment and general comings and goings (Richardson et al. 2007). Patients are also more anxious and may require frequent care activities that need to take place on a 24-hour basis, meaning that they are frequently awakened during the night (Freise 2008).

It is important to promote adequate sleep and rest for Harry as this may significantly decrease his agitation and confusion (NICE 2010). It may be advisable to place him in a side room, if this is available and without compromising any safety issues, remove noisy equipment and reduce the volume of alarms. Some studies have shown that ear plugs may be helpful for some patients but are not tolerated or liked by all (Scotto et al. 2009). For others, headphones with soft music may be appropriate to block more unpleasant sounds (De Niet et al. 2009). It is also important to reduce lighting whilst allowing continued safe observation of the patient; if lighting is a particular issue. The use of eye masks has been shown to improve sleep in some patients (Richardson et al.) but in Harry’s confused state would unlikely to be safe, (Richardson et al. 2007). It is vital, however to ensure that Harry’s safety is not compromised by Harry should have agreed additional rest periods during the day for additional sleep promotion. At these times visitors would be discouraged and nursing care activities kept to a minimum (Monsen and Edell-Gustafsson 2005). Clustering of nursing activities at night is recommended so that patients are disturbed less frequently and any non-essential care should be avoided if the patient is sleeping (Richardson et al. 2007).

Ensuring that Harry is able to see and hear adequately will also help to reduce confusion. Optimising sight and hearing would facilitate Harry in communicating and increase his ability to engage with his environment, increasing his familiarity with his surroundings, thus potentially reducing fear, anxiety and suspicions of harm that frequently accompany delirium. NICE (2010) and Morandi et al. (2009) highlight the importance of ensuring that any visual or hearing aids or devices normally used by the patient should be accessible to the patient and kept in good working order.

Chemical restraint

Wherever possible, pharmacological interventions involving sedatives should be avoided for patients with delirium as they may ultimately prolong critical care stay, contribute to confusion and have unwanted physiological effects for the patient (NICE 2010). If Harry has hyperactive delirium and is at risk of harming himself or others, it may be necessary to resort to drug management. This would involve the use of moderate sedation to protect necessary lines and infusions, allow for essential interventions and prevent harm to the patient (Webb et al. 2000).

In intensive care, obtaining the patient’s consent to such chemical restraint is a challenge and so rarely sought (Van Norman and Palmer 2001). Braine (2005) emphasised that prescribing and administering medication is not in itself suggestive of abuse. However, overprescription, inappropriate use or failure to regularly review medication, whilst neglecting to consider other methods of management, might constitute abuse. Patients who receive pharmacological restraint should be prescribed medication with the least side effects, and once the drug is given, the patient should be regularly reviewed and monitored (Braine 2005). The fundamental consideration is that any drug used to sedate a patient should not be counterproductive by exposing the patient to side effects or potential for serious consequences.

Before a sedative is used, the presence of pain should be ascertained. Harry should undergo a pain assessment, as he may not be able to verbalise or explain his pain, whilst confused, physiological evidence of pain should also be assessed (see Chapter 10 for management of the patient in pain).

Haloperidol is the drug currently recommended for use in delirium and Harry would most likely be prescribed a 2 mg twice-daily dose of oral haloperidol with 5 mg bolus doses prescribed for serious episodes of agitation (Webb et al. 2000; Chevrolet and Jolliet 2007; Morandi et al. 2009, NICE 2010).

Benzodiazepines have traditionally been used in the management of anxiety associated with delirium (Chevrolet and Jolliet 2007) but have become less popular as long-term use may contribute to factors that might increase the risk of delirium, and their effects may be too sedative in some older patients. In the UK, NICE (2010) recommend that the antipsychotic/neuroleptic agent, haloperidol, is used for the management of delirium episodes that cannot be managed by non-pharmacological interventions. It has the advantage of a rapid onset of action and may additionally lower the epileptic threshold (subclinical epileptic seizures do occur in these patients) and may have a favourable effect on the outcome of patients with delirium (Webb et al. 2000; Chevrolet and Jolliet 2007; Morandi et al. 2009; NICE 2010). Due to the fact that benzodiazepines are thought to exacerbate or even cause delirium, their use cannot be justified. Other agents, such as dexmedetomidine, olanzapine and risperidone, are currently under review and may replace the use of haloperidol in the future. Although haloperidol is recommended at present, there is no clear evidence in establishing either its overall effectiveness in treating delirium or its long-term effects (Morandi et al. 2009; NICE 2010).

Exposure/environment

Other factors that would predispose Harry to continuance of his delirium or delay his recovery should also be addressed.

Harry should be protected against the risks of further infection. All staff should undertake appropriate hand-washing practices to avoid cross infection. An aseptic procedure should be used when handling or changing the dressing on his central venous catheter (DH 2007). A daily review of all invasive devices should take place with the multi-disciplinary team and unwanted lines; especially, indwelling urinary catheters should be removed. These devices increase the risk of infection and can be a source of irritation to patients, possibly contributing or exacerbating agitation in delirium (Harvey 1996; Webb et al. 2000; Roundtable Meeting 2002).

Harry’s line sites and wounds should be observed for any clinical signs of infection. Swabs and specimens should be taken if indicated by clinical signs or suspicion of infection (DH 2007).

Harry should continue with regular nutritional assessments and his nutritional needs should be adequately maintained as poor nutrition may also be a precipitating factor in the development, or continuance, of delirium (follow NICE 2006) Clinical Guideline 32, for management of the adult with nutritional needs). Harry should begin oral nutrition as soon as he is able and should be encouraged to make his own food choices, as this will aid in restoring independence.

Harry should be assessed for his normal bowel function and for evidence of diarrhoea or constipation as these can lead to confusion and agitation. He should have regular toileting and bowel movements should be documented appropriately. An appropriate aperient should be prescribed and administered, if necessary, to maintain normal bowel function.

NICE (2010) also recommends that patients should be encouraged to mobilise as early as possible. Harry should be assisted to sit out in a chair for periods during the day and it may be prudent to time these to coincide with visitors as this will help to normalise him to his environment. Early mobilisation would also reduce his risk of thromboembolism and pressure sores (DH 2007).

The use of physical restraint

If Harry poses a danger to himself or others, it may also be necessary to consider the use of physical restraints (British Association of Critical Care Nurses (BACCN) 2004). Patients who are at risk of falling or removing invasive lines, drains or tubes that are essential in their care would fall into this category (BACCN 2004; Pfaff 2006). Many interventions in critical care compromise a patient’s ability to take decisions, which impacts on our professional obligation to ensure patient freedom, dignity and respect for autonomy (BACCN 2004). The multi-professional team in critical care must maintain a moral obligation to do no harm – non-maleficence – and to support good practice – beneficence (Beauchamp and Childress 1994) – by considering the risks and benefits of any form of restraint and justifying all management decisions in the best interests of Harry and in compliance with the Mental Capacity Act (DH 2005).

There is a paucity of UK literature that explores the subject of restraint in critical care (BACCN 2004), and most data originate in the United States of America (USA) or Australia. Where all conceivable alternative approaches to managing a patient with agitation and confusion have been exhausted, it is seen as lawful, in the UK, to use reasonable force to restrain a patient when they are at risk of self- harm or physical injury; they are imposing an immediate risk of physical assault on staff; or to prevent dangerous, threatening or destructive behaviour (Dimond 2002). Ideally, a consensus should be reached between healthcare professionals, patient and relatives, if possible, to ensure any restraint is reasonable and proportionate to the circumstances and to preclude allegations of assault (DH 2001; Royal College of Nursing (RCN) 2004). The use of physical restraints may actually exacerbate Harry’s agitation and can lead to injuries. A thorough documented assessment should be performed before taking a decision to use any form of physical restraint, and only devices manufactured for the purpose should be applied. Restraints should be taken off regularly to inspect the skin for any damage, and restraints should be removed as soon as Harry’s condition permits.

Conclusion

Delirium is a common complication for patients in critical care and can have serious and potentially life-threatening consequences for the patient. Critical care practitioners should be aware of the risks factors that can predispose or precipitate delirium in the critically ill patient and follow multi-modal interventions aimed at prevention, detection and early interventions to minimise the negative sequelae that can ensue from this condition.

Key learning points from the scenario

• Critical care patients are at high risk for the development of delirium and a delirium screen should therefore be performed on all patients.
  
• Management of delirium should focus on limiting current and potential risk of further episodes of delirium, limiting the negative physiological and emotional effects of delirium and reorientation to the environment (NICE 2010).
  
• The use of any form of restraint (chemical or physical) should be reserved for cases where all other conceivable alternative approaches have been exhausted and/or where the patient presents a danger to themselves or others.

Critical appraisal of research paper

Ely EW, Margolin R, Francis J, May L, Truman B, Dittus R, Speroff T, Gautam S, Bernard GR, Inouye SK (2001) Evaluation of delirium in critically ill patients: validation of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Critical Care Medicine 29(7), 1370–1379

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