Medical Concept: Delirium tips and tools

In Medical Concepts by Martin Badowski2 Comments

The Case

A 65-year-old woman presents to your emergency department (ED) feeling fatigued and weak. Her history is vague, and you have to redirect her conversation many times. She appears drowsy but is easily rousable. Her blood work, ECG, chest x-ray, urine all come back normal. When you return to re-asses her, you see that she is quietly resting in your ED with her daughter at the bedside. Her daughter tells you that the patient is “just tired today”; the two want to go home to get some proper sleep.

You astutely recognize that the patient may be delirious and require further work-up. What tools are available to help you confirm this diagnosis?

Background

Recently, a very well-written article by Dr. Woods highlighted an approach to geriatric patients in the emergency department1. As explained in the article, it is important to get a full functional assessment of the geriatric patient, and to be aware of the variety of tools available to do so. The elderly make up a large proportion of the ED population. With their many comorbidities, we focus much of our efforts on the common conditions that imminently threaten lives. The pleasantly confused quietly sleeping elderly, however, merit equal consideration and a thorough diagnostic evaluation.

Why is delirium important?

Delirium is present in approximately 7% to 10% of older ED patients, but often goes undetected2-4. In fact, studies have shown that emergency physicians identify delirium in only 16% – 35% of positive cases2-4 .Patients discharged home from the ED with unidentified delirium have 6 month mortality rates almost three times greater than those without delirium5. Delirium is an independent predictor of death among older adults seeking care in the ED6.

What is delirium?

Delirium, as defined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), is a syndrome of acute change in mental status marked by inattention, cognitive changes, and a fluctuating course7.

Diagnostic Criteria of Delirium in DSM V

A. Disturbance in attention (i.e., reduced ability to direct, focus, sustain, and shift attention) and awareness.
B. Change in cognition (e.g., memory deficit, disorientation, language disturbance, perceptual disturbance) that is not better accounted for by a preexisting, established, or evolving dementia.
C. The disturbance develops over a short period (usually hours to days) and fluctuates during the course of the day.
D. There is evidence from the history, physical examination, or laboratory findings that the disturbance is caused by a direct physiologic consequence of a general medical condition, an intoxicating substance, medication use, or more than one cause.

Keeping a wide differential diagnosis

The causes of delirium are complex and not fully understood. Delirium results from a wide variety of structural or physiological insults; consequently, the differential diagnosis is extensive. The mnemonic I WATCH DEATH is a useful memory aid8. In the current era of extensive polypharmacy, drugs are a common cause and it is helpful to have a good understanding of the most common culprits9.

Differential Diagnosis for Delirium

IInfectionsUTI, pneumonia, encephalitis
WWithdrawalAlcohol, benzodiazepines, sedatives-hypnotics
AAcute metabolicHypo/hyperglycemia, renal failure, hypo/hypernatremia, hyper calcemia etc.
TToxinsAlcohol, benzodiazepines, sedatives-hypnotics
Opiates, salicylates, indomethacin, lidocaine, dilantin, steroids, other drugs like digoxin, cardiac medications, anticholinergics, psychotropics
CCNS pathologyStroke, tumor, seizures, hemorrhage, infection, vascular
HHypoxiaAnemia, pulmonary/cardiac failure, hypotension
DDeficiencesThiamine (with ETOH abuse), B12
EEndocrineThyroid, hypo/hyperglycemia, adrenal insufficiency, hyperparathyroid
AAcute vascularSchock, hypertensive encephalopathy
TTraumaHead injury, post-op fall, subdural
HHeavy metalsLead etc.

An important concept to understand is that delirium itself has a spectrum of clinical presentations, each with their own implications. Hyperactive delirium is the type we most commonly associate with the diagnosis. Patients are loud and agitated, basically signaling to you that they have delirium (“Hey, I’m delirious over here!”). These patients have a good prognosis because they are diagnosed early. On the other hand, hypoactive delirium is associated with the quiet, sleeping, elderly patient who does not bother anyone; as a result, the diagnosis of delirium is often missed. There is also a mixed subtype, which includes characteristics of both.10

HyperactiveHypoactive
Agitated, loud, sympathetic nervous system changesLethargic, quite, withdrawn, mute, decreased LOC
Recognized earlierMore common and easier to miss
Better prognosisWorse prognosis
Prototype: alcohol withdrawal deliriumPrototype: hepatic encephalopathy

*delerium can be mixed with aspects of both hyper and hypoactive states

What tools are available to help diagnose delirium?

As always, it is important to look at the vital signs, check a capillary glucose, and complete a careful history and physical.  Once the patient is stabilized, and any easily reversible causes are fixed, obtain a collateral history from family, allied health professionals, or nursing home staff to establish the acuity of the change in cognition. Establishing the patient’s baseline status is essential in diagnosing delirium8, 11.

Diagnosing delirium based on the DSM-5 criteria listed above is labour-intensive and requires psychiatric expertise. In a noisy, time pressured environment it can be difficult to do.

A recent systematic review by Lemantia and colleagues (2014)12 took a look at delirium screening tools in the ED, compared to the old DSM IV criteria and identified the Confusion Assessment Method (CAM) as the only tool validated in the ED setting (Sensitivity 0.94, Specificity 0.96),  although the quality of evidence was admittedly weak. The CAM tool takes less than 5 minutes to apply and correlates well with both the mini mental status exam and the DSM IV criteria (the criteria for delirium have been updated in the DSM 5 based on current available evidence but the change has little clinical impact). 13

There are many variations of the CAM that have been studied within the ED including the CAM-ICU, which has been recently validated within the ED. In older ED patients (age >65), the CAM-ICU is highly specific; sensitivity is modest14.

A recent variation of the CAM, called the modified Confusion Assessment Method for the ED (mCAM ED) is currently being evaluated in studies. This tool screens all patients greater than 65 years of age with a quick inattention screen; if positive, the tool then uses a modified CAM to determine delirium15. Unfortunately, the initial study was small and not able to determine sensitivity or specificity compared to the old DSM IV criteria.

Han and colleagues16 recently proposed a delirium screening strategy. Their strategy uses a highly-sensitive quick screen at triage to rule-out delirium. This is called the Delirium Triage Screen (DTS), and incorporates the patient’s level of consciousness and attention. If no concerning features are identified on initial screen, the assessment is concluded. On the other hand, if the screen is positive, the physician then performs the brief Confusion Assessment Method (bCAM), a further variation of the CAM-ICU. Compared to using DSM-IV-TR criteria, the sensitivity and specificity of this method when performed by an ER physician were 82% and 95.8% respectively16. This tool needs further testing and validation in larger ED settings.

While both Rosen’s17 and Tintinalli11 describe the use of the Mini Mental Status Exam (LR+  6.3 and LR 0.19) 11 and the Quick Confusion Scale18 in the diagnosis of delirium, these tools were not studied to look for delirium specifically and therefore confounded by other diagnosis such as dementia and depression which is left to the physician to determine (Table 3)8.

Bottom Line

Delirium is an important clinical entity to recognize due to its association with mortality rate and the high miss rate within the ED. Delirium exists as a spectrum from hypoactive to hyperactive presentations, which makes it difficult to diagnose. The differential diagnoses for delirium is extensive, and we must have a good knowledge of a wide variety of causes. In terms of diagnosis, have a high clinical suspicion for delirium in all elderly who present to the ED. There are multiple tools available to help you diagnose delirium. Although no one tool currently exists which has been extensively validated, the CAM and the CAM-ICU may be the most helpful tools to include in your diagnostic toolbox for delirium.

Delirium Diagnostic Tools

ToolProsCons
CAM

Sens 94.0%, Spec 96.0%
+LR= 23.5 and –LR= 0.06
-Well studied
-Validated within the ED for delirium
-Correlates well with MMSE
-<5 min to complete
Good sensitivity
-Not well validated for novice learners
CAM-ICU

Sens 72.0%, Spec 98.6%
+LR= 51.3 and -LR= 0.28
-Well studied and validated within the ICU and ED for delirium
-Does not require verbal communication or use of hands
-High specificity
-Low sensitivity
mCAM-ED

no reported LR
-Designed specifically for delirium screening
-< 5 minutes to complete
-Easy to use
-Not well studied, no sensitivity/specificity reported
-Not validated
DTS + bCAM

Sens 82.0%, Spec 95.8%
+LR= 19.52 and -LR=0.18
-Designed specifically for delirium screening
-<5 minutes to complete
-Easy to use
-High specificity
-Needs further studies
MMSE

+LR= 6.3 and -LR= 0.19
-Well studied,
-Validated within the ED
-Time consuming >7 mins
-Requires use of drawing and completion of tasks with hands
-Designed to screen for cognitive impairment; not specific for delirium

Links to Delirium Screening Resources

References

  1. Woods, R. Approach to geriatric patients: Functional assessment in the ED. Boring EM, 2015. http://canadiem.org/2015/01/12/approach-to-geriatric-patients/
  2. Lewis LM, Miller DK, Morley JE, et al. Unrecognized delirium in ED geriatric patients. Am J Emerg Med 1995;13:142-5
  3. Elie M, Rousseau F, Cole M, et al. Prevalence and detection of delirium in elderly emergency department patients. CMAJ 2000;163:977-81. PMID: 7893295
  4. Hustey FM, Meldon SW. The prevalence and documentation of impaired mental status in elderly emergency department patients. Ann Emerg Med 2002;39:248-53 PMID: 11867976
  5. Kakuma R, du Fort GG, Arsenault L, et al. Delirium in older emergency department patients discharged home: effect on survival. J Am Geriatr Soc 2003;51:443-50. PMID: 12657062
  6. Han JH, Shintani A, Eden S, et al. Delirium in the emergency department: An independent predictor of death within 6 months. Ann of Emerg Med 2010; 56(3):244-52. PMID:20363527
  7. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Washington, DC: Author.
  8. Smith J, Seirafi J. Delirium and dementia. In: Marx JA III, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine Concepts and Clinical Practices. 7th ed. Philadelphia, PA: Elsevier; 2010:1367–1373
  9. Agostini JV, Inouye SK. Delirium. In: Hazzard WR, Blass JP, Halter JB, et al, eds. Principles of Geriatric Medicine & Gerontology. 5th ed. New York, NY: McGraw-Hill; 2003:1503–1515
  10. Han JH, Zimmerman EE, Cutler N, et al. Delirium in older emergency department patients: recognition, risk factors, and psychomotor subtypes. Acad Emerg Med 2009;(16):193-200. PMID: 19154565
  11. Tintinalli, JE, Stapczynski SJ, Ma JO, Cline D, Cydulka R, Meckler G. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York, NY: McGraw-Hill, 2010. Print.
  12. LaMantia MA, Messina FC, Hobgood CD, Miller DK. Screening for delirium in the emergency department: a systematic review. Ann Emerg Med 2014;63(5):551–60.e2. PMID:24355431
  13. American Psychiatric Association. Highlights of changes from DSM-IV-TR to DSM-5. American Psychiatric Publishing, 2013.
  14. Han JH, Wilson A, Graves AJ, et al. Validation of the Confusion Assessment Method for the Intensive Care Unit in older emergency department patients. Acad Emerg Med Off J Soc Acad Emerg Med 2014;21(2):180–7. PMID: 24673674
  15. Grossmann FF, Hasemann W, Graber A, Bingisser R, Kressig RW, Nickel CH. Screening, detection and management of delirium in the emergency department – a pilot study on the feasibility of a new algorithm for use in older emergency department patients: The modified Confusion Assessment Method for the Emergency Department (mCAM-ED). Scand J Trauma Resusc Emerg Med 2014;22:19. PMID: 24625212
  16. Han JH, Wilson A, Vasilevskis EE, et al. Diagnosing delirium in older emergency department patients: validity and reliability of the delirium triage screen and the brief confusion assessment method. Ann Emerg Med 2013;62(5):457–65. PMID: 23916018
  17. Marx, J. Rosen’s emergency medicine: concepts and clinical practice. 7th ed. Philadelphia, PA: Mosby/Elsevier; 2010
  18. Stair TO, Morrissey J, Jaradeh I, Zhou TX, Goldstein JN. Validation of the Quick Confusion Scale for mental status screening in the emergency department. Intern Emerg Med 2007;2(2):130–2. PMID: 17619832

 

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Martin Badowski

Martin Badowski

PGY-2 Family Medicine, Queen's University
Martin Badowski

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