| Prevention of Complications in Hospitalized Patients Part VI: Delirium | ||
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CLINICAL REVIEW Prevention of Complications in Hospitalized Patients Part VI: DeliriumMichael S. Galindo, M.D.The Clinical Scenario An 84-year-old woman who lives alone develops a productive cough and fatigue over several days. She presents to the emergency department, where examination and a chest radiograph reveal a multilobar pneumonia. She is admitted to the hospital, given intravenous antibiotics and fluids, and remains stable on supplemental oxygen. On her second night in the hospital, she sleeps poorly, calls out to her nurse, and complains of people stealing from her. Over the next several days, she is alternately agitated and lethargic and has trouble cooperating with physical therapy. She is eventually discharged to a rehabilitation home but has a prolonged and difficult recovery. She is unable to return to her previous level of independent living and requires ongoing nursing care. What interventions might have helped to prevent her abrupt decline in cognitive ability? IntroductionDelirium is an acute change in consciousness and cognition with a fluctuating course that is usually precipitated by an underlying medical illness or drug effect, and is not explained by prior dementia. The change in cognition appears over a short time and most prominently affects attention, orientation, memory, and language.1 Patients are typically older and have a history of dementia, although it can affect patients of any age including those with normal baseline cognitive ability.2-5 It is particularly common and problematic in patients hospitalized for an acute illness4,5 or following a major surgery.6,7 Despite its familiarity, delirium is frequently overlooked and remains a significant cause of excess morbidity and mortality. This review aims to discuss the features of the condition in hospitalized patients and to recommend steps which clinicians and hospitals can take to prevent its occurrence, with a primary focus on general medicine inpatients. Scope of the ProblemThe true burden of delirium is difficult to determine because it is easily missed in hospitalized patients. Prospective studies have shown that 15% to 30% of all patients older than 65 years who are admitted to an acute care hospital will either have delirium at the time of admission or develop delirium during their stay.2-5 Up to 40% of older adults will suffer delirium post-operatively,6 and at least 70% of all terminally ill patients will have some degree of delirium during the last several weeks of life.8 All told, an estimated 2.3 million people will be affected by delirium and require care that costs 4 billion dollars each year.9 Delirium has grave prognostic implications for older patients, as it both signals a serious underlying illness and predisposes the patient to further complications. Agitation increases the risk for injuries, interferes with important treatments, lines, or monitors, and renders it impossible to perform necessary tests. Lapses in cognition interfere with making important medical decisions, prevent assessment of unpleasant symptoms, and cause emotional distress to both the patient and their loved ones. There is also accumulating evidence that episodes of delirium can irreversibly damage patients' cognitive and functional powers. Rates of institutionalization are increased, and it is common for patients to have delayed and incomplete cognitive recovery. In one study, an episode of delirium in the hospital was associated with a mean loss of 5 points from baseline on the Mini-Mental State Exam at 1 year. These effects apply not only to frail older adults, but also to those who had previously lived independently.10-12 By initiating a downward spiral in function, delirium can increase the risk of death after an episode by 3-fold, both during the hospital stay and in the following year3,10,13 Precipitating and Predisposing FactorsSystematic prevention of delirium begins with awareness of the patient groups at greatest risk. Patients with a history of damage to the central nervous system from either stroke or dementia are most at risk for delirium. The fragile brain, like the fragile heart or lung, is more prone to acute dysfunction, takes longer to recover from delirium, and may not return to its prior level of function. Male gender, polypharmacy, advanced age, malnutrition, and a high burden of comorbidity have also been identified as independent contributors to delirium.3,5,14-16 Delirium requires a triggering event, but it can arise from almost any insult and the disturbance may be small.14-16 Medications are frequent culprits, and although many medications have been implicated in delirium, the most important ones are listed in Table 1.14-17 The simple act of admitting a patient to the hospital can be disorienting for many patients. Sleep deprivation contributes to cognitive impairment and is quite common, as a result of frequent drug dosing and vital sign checks, beeping alarms, hallway noise, and physical discomfort. Restraints, whether real or perceived, can be a factor: intravenous lines, cardiac monitors, oxygen tubing, and sequential compression devices all hold the patient down and may add to agitation. Urinary catheters are triply dangerous as they are irritating, restrain the patient in bed, and can cause iatrogenic urinary tract infections.17 Finally, the nature of the admission diagnosis is an important risk factor. Patients with fractures, large changes in blood pressure, infections, and volume depletion are most prone to developing delirium.2,16 At the time of admission, clinicians should assess patients' level of risk for delirium and institute active preventive measures if that risk is determined to be high.  Preventive MeasuresStudies of delirium prevention have been conducted both on general medicine wards and in the peri-operative setting. A systematic review by Siddiqi et al in 2007 found no high quality randomized controlled trials of delirium prevention in general medicine inpatients. The only studies satisfying their rigorous criteria were in the post-operative setting. Several trials of slightly lower quality, however, have evaluated strategies that may be effective in general medicine patients.18 Taken together, these trials offer a rough consensus of the measures most likely to be effective in preventing delirium. One study in Siddiqi's analysis, The Elder Life Program by Inouye et al, involved patients older than 70 years who were admitted to the hospital. Using a controlled-matching method, patients were assigned to either usual care or a special program that addressed 6 domains: orientation cues, cognition, visual impairment, hearing impairment, immobility, and dehydration. The program showed a significant reduction in the incidence and duration of delirium, but no effect on the severity of delirium.19 Marcantonio et al conducted a prevention study on elderly patients undergoing hip arthroplasty following a fracture. Patients were randomly assigned to usual care or to geriatric consultation which used a standard protocol. Similar to the Elder Life Program above, the protocol focused attention on ten domains of care: CNS oxygen delivery; fluid/electrolyte balance; pain control; medications; bowel and bladder function; nutrition; early mobilization and rehabilitation; reducing other major complications; environmental cues; and proper treatment of agitated delirium. Geriatric consultation using a standard protocol resulted in a 36% reduction in delirium and a 60% reduction in severe delirium.7 In a before-and-after study, Naughton et al evaluated the effectiveness of an acute geriatrics unit. Patients with new or baseline cognitive impairment in the emergency department were triaged to a geriatrics ward, where staff used specialized guidelines for behavior disturbances. The guidelines focused on improved and standardized assessment of mental status, emphasis on non-pharmacologic treatment of behavior disturbances, and optimizing medication use. Over a 9-month period, the study demonstrated a 50% reduction in the prevalence of delirium as well as improved prescribing practices.20 In a similar study, Lundstrom et al designed a medical ward that used education on the assessment, prevention, and treatment of delirium as well as reorganizing the delivery of care to a patient-centered model. They showed that compared to a control ward, patients admitted to the intervention ward had a shorter duration of delirium and decreased length of stay.21 To date, there have been no controlled trials using medication to prevent delirium in general medicine patients. Low-dose haloperidol did not decrease the incidence of post-operative delirium, but was effective in reducing its severity and duration as well as shortening hospital stay.22 Several trials using the cholinesterase inhibitor donepezil to prevent post-operative delirium have shown no effect,23 but further trials are currently ongoing.
As part of their comprehensive approach, most studies have used systematic methods to detect delirium early. The Confusion Assessment Method (CAM)(Figure 1) is a simple and sensitive method that is based on the DSM-III criteria for delirium.24 It has been validated in a variety of contexts, and is frequently used in prevention studies. It has a sensitivity of approximately 94%, a specificity of 89%, and has demonstrated high inter-rater reliability.25 Although highly varied in their particulars, the above studies demonstrate a compelling approach to the prevention of delirium. Improved efforts to detect delirium, re-organization of care toward a patient-centered model, and multidisciplinary education of hospital staff are likely to improve outcomes related to delirium. The optimal preventive methods remain to be determined in large, randomized trials. Almost all studies use a multi-faceted approach to prevention, making it difficult to determine the importance of individual components of the intervention. Strategies centered around entire medicine wards may be more effective than consultative interventions. Figure 2 summarizes the recommended preventive measures in hospitalized patients at risk for delirium. ConclusionDelirium is a common and preventable cause of debility in hospitalized patients. As a heterogeneous disease with many causes, any prevention method should be multidisciplinary and comprehensive in scope. Clinicians should be alert to the common risks factors and precipitants, provide for proper patient orientation and rehabilitation, and take special steps to minimize inappropriate medications, restraints, and urinary catheters. In patients at risk for delirium, clinicians should briefly assess cognitive status on a regular basis, preferably using standard assessments such as the Confusion Assessment Method. REFERENCES
Submitted on October 31, 2008 |
© copyright 2009 Anonymous & UCLA Department of Medicine