Cognitive impairment is a recognized predictor of acute delirium, particularly in the postoperative period. In fact, in a recent systematic review of delirium prediction, cognitive impairment was second only to age as the most common predictor of delirium (van Meenen, van Meenen, deRooj, & terRiet, 2014). Delirium is an acute change in mental status, cognition, and attention that also includes disorganized thinking and altered levels of consciousness (see Box 1). Patients with delirium after surgery recover more slowly than those without delirium and, as a result, have an increased length of stay and hospital cost (Rudolph & Mercantonio, 2011). Although the exact mechanism of postoperative delirium is not clear, orthopaedic patients are at a heightened risk for delirium due to several predisposing and precipitating factors such as older age; depression; abnormal preoperative glucose, sodium, potassium, and albumin levels; vision and hearing impairment; and/or admission from a nursing home (Boldt, 2010; Rudolph & Mercantonio, 2011; Wang, Xu, Wei, Chang, & Xu, 2016). Estimates of up to 24% of patients undergoing any orthopaedic procedure have been reported as experiencing delirium and its associated cognitive impairment (Galanakis, Bickel, Gradinger, Von Gumppenberg, & Forst, 2001). The onset time among these patients ranged from 7 hours to 16 days after the operation, with an average of 2.8 days postsurgery (Wang et al., 2016). The prevalence was highest between postoperative days 2 and 5 (Galanakis et al., 2001). Patients with a hip fracture are the most vulnerable of the orthopaedic surgery population as the incidence of delirium is the most frequently reported postoperative complication in this group; symptoms often occur as early as the first postoperative day (Robertson & Robertson, 2006). Notably, Bruce, Ritchie, Blizard, Lai, and Raven (2007) in a meta-analytic systematic review reported incidences of delirium in patients following hip fracture repair to occur up to 92% of the time and Marcantonio, Flacker, Michaels, and Resnick (2000) reported that delirium was predictive of poor postoperative recovery of functional status and mobility among patients with hip fracture. The adverse effects of delirium among those undergoing hip fracture repair warrant attention although any elderly patient undergoing an orthopaedic surgical procedure should be considered at risk for cognitive impairment and the development of acute delirium.

Box 1. Delirium Facts

Given the evidence that 40% of all delirium is preventable (Leslie & Inouye, 2011) and that delirium is not always resolved at discharge (Girard et al., 2010) or even reversible in many cases, institution of measures that prevent its occurrence or shorten its duration by early recognizing its symptoms is of utmost importance. The purpose of this article, therefore, is to provide evidence-based recommendations to prevent acute delirium using bundles of care. Bundles of care are a set of three to five independent, evidence-based interventions that, when implemented together, result in significantly better outcomes than when implemented individually (Resar, Griffin, Haraden, & Nolan, 2012; Institute for Healthcare Improvement: http://www.ihi.org). Care bundles are currently being used with success to prevent ventilator-associated pneumonia, gastritis, and deep vein thrombosis often associated with mechanical ventilation and central line infections. For example, in a systematic review of 8,515 surgical patients and surgical site infections (SSI), Tanner, Padley, Assadian, Leaper, Kiernan, and Edmiston (2015) reported that surgical care bundles reduced the risk of SSI compared with standard care, with a confidence interval (CI) of 0.55 (0.39-0.77; p= .0005). The use of a bundled approach to reduce delirium rates has also been successful-Milisen, Lemiengre, Braes, and Foreman (2005) reported that surgical patients without premorbid dementia or functional decline benefited most from any intervention, whereas multicomponent interventions were most effective for patients who exhibited one or two risk factors of delirium, specifically visual impairment, severe illness, and cognitive impairment. In this study, delirium was prevented in one-third of patients, and the incidence of severe delirium was decreased by more than one-half. A cognitive impairment bundle should consist of establishing mechanisms for preventive strategies related to ongoing assessment of cognition, continuing orientation, and early mobilization and socialization.

Strategies for Early Identification and Prevention

Assessing Cognition

The cognitive impairment seen postoperatively among orthopaedic patients is generally mild. Mild cognitive impairment (MCI) is an intermediate stage between the cognitive decline of aging and the more severe state of dementia (Mayo Clinic, 2018). The patient may be restless and have trouble remembering, concentrating, or making decisions. Mild cognitive impairment is classified into two subtypes: amnestic and nonamnestic (Petersen, 2011). Amnestic MCI is clinically significant memory impairment that does not meet the criteria for dementia. Typically, patients are increasingly forgetful. However, other cognitive capacities, such as executive function, language, and visuospatial skills are intact. The nonamnestic MCI seen in acute delirium is characterized by a subtle decline in functions not related to memory. Although the symptoms of MCI are not severe enough to interfere significantly with daily life (see Table 1), those with MCI and delirium were more often discharged to a post-acute facility (risk ratio [RR]= 1.4, p< .001) and had increased risk for greater levels of impairments in cognitive functioning (RR = 3.6, p< .001) (Racine et al., 2017). Notably, there is a heightened risk for further cognitive decline as cognitively normal octogenarians who developed delirium during hospitalization (known as acute incident delirium) were more likely to be diagnosed with dementia at 3-year follow-up than those who did not experience delirium (Rahkonen et al., 2000; Marcantonio et al., 2001). Although some data suggest that the rate of reversion to normal cognition may be as high as 25%-30%, recent prospective studies have shown lower rates (Guo, Sun, Wang, Li, & Liu, 2014; Manly et al., 2008).

Table 1. Signs of Cognitive Impairmenta

Screening patients for the cognitive impairment associated with acute delirium is essential for facilitating early identification and prevention and to increase the likelihood of timely delirium management. Proactively prioritizing patients through the use of a validated delirium assessment tool is the first step in managing orthopaedic patients at risk of developing delirium. This close monitoring and implementation of delirium-preventive strategies can assist in decreasing incident delirium rates.

The primary characteristic of impaired cognition is fading into and out of lucidity with an inability to attend (inattention) to the environment such that the patients appear to know what is going on at one moment and the next is disorganized in their thinking (disorganized thinking; Maldonado, 2017). Inattention is seen in the patient as difficulty focusing, being easily distracted, or having difficulty following a conversation. The patient may seem dazed or fixated on one object in the room. There may be no eye contact. Asking the patient to recite the months December to July backward is a simple and brief method to assess for inattention. Most patients should be able to recite the months forward; however, reciting the months backward requires concentration, which can be impaired in patients with delirium (Han, 2015).

Disorganized thinking is a failure to be able to think straight. Thoughts come and go rapidly. The patient is unable to concentrate on one thought for very long. Thoughts become fragmented making conversation difficult. The patient may ramble or make irrelevant comments, have unclear or illogical flow of ideas, or unpredictable switching from subject to subject. Reponses to questions are often nonsensical. Disorganized thinking can be assessed by asking yes/no questions and then presenting a command, for example, Can a stone float on water? followed by Hold up two fingers (Han, 2015).

When assessing for cognitive impairment, a cognitive baseline should be conducted on admission and recorded. Ongoing assessment should be conducted at least once daily. This assessment can be a brief but must include assessment of orientation, attention, and memory. There are several validated assessment tools that can be used in a noncritical care area, such as orthopaedics (see Table 2). When choosing an assessment tool, it is important to determine its sensitivity (true positive rate or probability of detection) and specificity (true negative rate or percentage of healthy people who are correctly identified as not having the condition). For example, the Rapid Assessment Test for Delirium is 90% sensitive and 84% specific and the Stanford-Proxy Test for Delirium is 79% sensitive and 90.8% specific (Maldonado, 2017). On the contrary, the Confusion Assessment Method (CAM), developed by Inouye et al. (1990), demonstrated sensitivities from 94% to 100% and specificities from 90% to 95% in a systematic review of 236 studies (Wei, Fearing, Sternberg, & Inouye, 2008). A brief CAM (bCAM) is also available (see Table 2). The bCAM takes less than 2 minutes to complete and has been found to be 84% sensitive and 96% specific for delirium (Han, 2015). Using different questions that take differing amounts of time, both the CAM and the bCAM assess the patient for acute onset of mental status change or a fluctuating course of altered mental status, inattention, disorganized thinking, and an altered level of consciousness. Patients must be awake or arousable to be assessed using either of these tools. A diagnostic interview for confusion (3D-CAM), based on the original CAM algorithm, is also available. The 3D-CAM is a 3-minute delirium assessment. The major difference between the 3D-CAM, the CAM, and the bCAM is that the 3D-CAM uses both subjective questions and observation to assess for delirium. This allows for assessment of patients with severe drowsiness or agitation, which the other two do not (Marantonio et al., 2014). The 3D-CAM has a sensitivity of 95% and specificity of 94% (Marantonio, 2014). The CAM, bCAM, and 3D-CAM require training to use and manuals are available (see Box 2).

Box 2. CAM Training Manuals

Table 2. Delirium Assessment Tools for Use in Non-Intensive Care Unit Settings

A newer tool that allows bedside nurses to assess patients' cognition that does not require specific training is the AWOL. The AWOL is easy to learn and requires very little time to administer and chart. It is primarily useful in identifying those at risk for cognitive impairment (see Table 2). In a study by Douglas et al. (2013) among patients with an AWOL score of 2-4, the risk of developing delirium was 25% (positive predictive value), compared with 3.0% for those with a score of 0-1 (negative predictive value, 97%); p< .001 using Fisher's exact test. The AWOL correctly classified 17 of the 28 patients (61% sensitivity) who developed delirium in the cohort. Specificity was 87%.

Fick et al. (2018) recently piloted a 2-step delirium detection-screening protocol among 24 hospitalized elderly patients. In Step 1, patients are asked: "Please tell me the day of the week" (screens for orientation) and "Pease tell me the months of the year backwards starting with December" (screens for inattention). If either or both items are incorrect, Step 2, a 3-minute diagnostic assessment, follows. Certified nursing assistants (CNAs) completed Step 1 and reported findings to the nursing staff. Thereafter, physicians and RNs completed the assessment. The authors reported that the protocol achieved high sensitivities and specificities among RNs, CNAs, and physicians, although the rates were not provided. This very brief screening tool using a CNA as an initial screener holds promise to improve delirium identification.

Use of an assessment tool can easily be incorporated into the admission interview process. The ideal environment to conduct this initial assessment is in a quiet room, without distractions (e.g., close the door and turn off the television/iPad/iPhone, etc.). General guidelines for the assessments include the following: (1) Make sure the patient can see and hear you. If the patient uses hearing aids or wears glasses, these should be in place at the time of each assessment; (2) Do not give verbal praise or indicate correct or incorrect answers (you may want to ask any family present to leave the room); and (3) Document exactly what you see and hear; do not interpret behaviors. Be very specific in your descriptions. Instead of patient disoriented, write patient stated she was atop the Eiffel Tower; and rather than writing patient inattentive, write patient easily distracted by noises (Marcantonio, 2017).

Continuing Orientation

Continuing orientation is the process of frequently orienting a person at risk for cognitive impairment and delirium to time, person, and place to keep the patient from becoming disoriented. It differs from reorientation as it should begin on admission before any signs of disorientation appear. Disorientation is an altered mental state. A person who is disoriented may not know his or her location and identity or the time and date. The patient may think that it is nighttime during the day, may climb into the wrong bed, or eat from another patient's tray. They may also wander.

Orientation to time has been reported to be one of the most efficient measures for discriminating between those with and without delirium and in predicting cognitive decline (Lou, Dai, Huang, & Yu, 2003). Failure to identify the year correctly was reported as the single most valuable sign of cognitive impairment, combining high sensitivity (95%) and specificity (86.5%; O'Keeffe, Mukhtar, & O'Keeffe, 2011). In a stepwise logistic regression, not knowing the year (odds ratio [OR]: 37.2 [95% CI: 13.1-101.3]), not knowing the month (OR: 3.85 [CI: 1.43-10.38]), and an error of 1 hour or more in time of day (OR: 2.76 [CI: 1.0-7.46]) were independent predictors of cognitive impairment (O'Keeffe et al., 2011).

Strategies that can be used in a continuing orientation protocol are as follows:

* Provide appropriate lighting and clear signage.

* Place clocks in each patient room.

* Open the shades or blinds during the daytime.

* Provide reminders on date, time of day (day or night), and location at least twice daily. Explain to the patients where they are, who they are, and your role. Upon entering the patient room, say: Good Morning and patient name or Good Afternoon and patient, etc. You can add I am your nurse today for continuing time, person, and place orientation. Explain reason for admission to the unit to the patient daily.

* Facilitate regular visits from family and friends. The presence of relatives provides a sense of control for patients by encouraging feelings of security and orientation (Hunter & Cyr, 2007; Meagher, 2001).

* Ask family members to bring in familiar objects or pictures.

* Resolve any reversible causes of sensory impairment, such as impacted earwax, and ensure that hearing and visual aids are available and used by those who need them and that they are in good working order.

* Move the patient to another environment only if necessary. A change in location can cause disorientation.

Early Mobilization and Socialization

Early mobilization is getting the patient out of bed to sit in a chair and/or walk around the nursing unit as close to the time of surgery as possible. Originally used to reduce the risks associated with bed rest, the beneficial effects of early mobility now include shorter duration of delirium and reduced postoperative complications (Schweickert et al., 2009) and reduction in length of stay (Muehling et al., 2009; Muller et al., 2009) and mechanical ventilation days (Schweickert et al., 2009), thus lowering overall costs. In a study of intensive care unit patients, early physical and occupational therapy led to reduced incidence and duration of delirium, less days intubated, and a more likely return to independent functional status at discharge (Guerra, Parminder, Singh, & Taylor, 2015).

Strategies for early mobilization and socialization protocol include the following:

* Work with physical therapists to devise a mobilization program that includes strategies to be used on the nursing unit and is based on patient needs and capabilities.

* Ensure that mobilization (in or out of bed) is begun within 24-48 hours of admission.

* Use physical restraints only to control episodes of dangerous agitation.

* Allow the patient to walk independently as possible.

* Engage the patient in conversation while mobilizing. Encourage the patient to talk with others while walking in the corridor.

Conclusion

Primary prevention is the most effective strategy to maintain cognition and prevent delirium. To decrease the incidence of delirium, keep patients safe, maintain their functionality, or plan for safe discharge to their original place of residence, all older adults admitted for orthopaedic surgical procedures should be cared for using a cognitive impairment bundle. Up to 24% of patients undergoing any orthopaedic procedure experience delirium and its associated cognitive impairment. Patients with a hip fracture are the most vulnerable of the orthopaedic surgery population as the incidence of delirium is the most frequently reported postoperative complication in this group.

References