There are three psychomotor variants of delirium: hyperactive (prevalence, 25%), hypoactive (prevalence, 50%), and mixed disorder, with features of both (prevalence, 25%).16 This patient appeared to have the hyperactive form of delirium. As mentioned previously, patients with the hyperactive and mixed disorders are more likely to be physically and chemically restrained. Indeed, this patient was placed in physical restraints when she became confused and hyperactive. The Joint Commission has published standards for restraint use. The key elements of the standards’ implementation are “the device’s intended use (such as physical restriction), its involuntary application, and/or the identified patient need that determines whether use of the device triggers the application of these standards.”17 As such, consideration should be given to the following questions prior to restraining a patient:
•What is the intended effect of the restraint?
•Is there another means by which the intended effect can be achieved?
•Is this the least invasive restraint?
•Is the use of restraints in the patient’s best interest?
•Am I restraining the patient for secondary benefits (to limit phone calls/pages, to assuage nursing requests, too busy to see patient, etc.)?
•When is the restraint going to be removed?
Although necessary at times, the use of restraints must be considered carefully prior to application for three key reasons. First, restraints have been found to be independently associated with the development of delirium.18,19 Second, restraints may exacerbate underlying hyperactive behavior. Finally, by restricting patients to bed rest, restraints further limit external stimuli, which in itself may increase the risk for delirium.20
Case and Commentary: Part 2
The doctor was called, and an arterial blood gas was performed. The patient’s PaO2 was 91 mmHg, but the PaCo2 was 58 mmHg, a marked increase since admission. Despite the patient’s deteriorating clinical condition, the patient’s worsening level of consciousness was attributed to “senile dementia” and not impending respiratory failure (as evidenced by the significant carbon dioxide retention). No further action was taken. Over the course of the day, the patient developed worsening respiratory distress and became comatose, and eventually was transferred to the ICU. She subsequently developed respiratory failure requiring intubation and renal failure requiring dialysis. Her condition did not significantly improve, and she eventually died two weeks later.
This patient was incorrectly diagnosed with dementia, despite a presentation most consistent with delirium. The diagnosis of delirium follows the diagnostic algorithm of the Confusion Assessment Method (CAM) and involves elements of history and physical examination.21 The CAM algorithm has four features:
•Feature 1 is acute onset and fluctuating course. Presence of this feature can generally be obtained from family and nursing history.
•Feature 2, inattention, is assessed through brief cognitive assessment such as serial 7s (take the number 100 and subtract 7, keep going until I tell you to stop); digit span (I am going to read you some numbers and I want you to repeat them to me backwards); or asking the patient to recite months of the year or days of the week backwards.
•Feature 3, disorganized thinking, can be assessed via response to interview questions. For example, does the patient respond inappropriately or tangentially?
•Feature 4, disturbance of consciousness, helps identify the three psychomotor variants (hyperactive, hypoactive, mixed disorder).
Patients demonstrating features 1 and 2 along with either feature 3 or 4 should be considered to have delirium until proven otherwise.11 The diagnosis of “senile dementia” is not appropriate in the setting of acute illness. The acute onset of confusion and hyperactivity in this case should have prompted cognitive assessment for inattention and disorganized thinking; such an assessment would likely have led to the correct diagnosis of delirium.
A thorough history and physical examination are required for patients suspected of having delirium. The neurologic examination is especially important because while acute, focal neurologic changes require neuroimaging, patients without such changes can usually have neuroimaging deferred, reserved for situations in which the cause cannot be determined from a medical/metabolic workup.22 Core laboratory tests to identify electrolyte abnormalities, renal function, and infection (complete blood count and urinalysis) are warranted in all patients. The history and physical examination should guide further laboratory testing. An arterial blood gas was appropriately performed in this case, but it appears that the physician failed to tie the results (marked carbon dioxide retention) together with the patient’s delirium.
All patients should have a thorough review of medications that may contribute to delirium, particularly benzodiazepines, anticholinergic medications, and psychoactive medications.23 All medications that can precipitate delirium should be discontinued or have dosages lowered. Further consideration should be given to drugs that have recently been stopped and may cause a withdrawal syndrome (alcohol, chronic opioids, antidepressants, etc.).