An Overview of Delirium in the Hospital Setting

An Acute Confusional State

Doctor talking to senior woman lying in hospital bed
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Delirium, also known as acute confusional state or encephalopathy, is a common condition in hospital patients involving a sudden and often temporary deterioration in mental and cognitive functioning. While a portion of all hospitalized patients may experience delirium, the condition occurs in up to 30% of hospitalized older adults. Delirium is usually transient and tends to resolve as the patient's condition improves, however it is also potentially serious. It's associated with longer hospital stays, increased risk of morbidity, and a higher likelihood of developing dementia. While it can be unnerving to observe a loved one experiencing delirium, hospital staff are well-acquainted with the condition and numerous coping strategies can be used.


Patients suffering from delirium may experience many symptoms that vary in duration and severity:

  • Disorientation—such as not knowing where they are, what has recently happened, or the date
  • Inability to recognize friends and loved ones
  • Visual hallucinations
  • Agitation—which may manifest as screaming, struggling to get out bed, or attempting to remove IV lines, catheters, or tubes
  • Fear and paranoia
  • Difficulty or inability to sustain attention for a prolonged period
  • Lethargy or unresponsiveness

The "hyperactive" subtype, accompanied by severe agitation and possible aggression, is seen in only about 10 percent of delirious patients while the “hypoactive" subtype, usually characterized by lethargic and unresponsive behavior, affects more than 50 percent of those presenting with delirium. The remaining proportion of patients with delirium are either of the “mixed” subtype, alternately suffering from hyperactive and hypoactive symptoms, or a fourth subtype that shows few visible symptoms.

Fluctuation in severity is a hallmark of delirium: a patient may seem like their usual self one minute, and the next minute they may exhibit confusion, agitation, or other symptoms of delirium. Though these fluctuations may last minutes or even hours, delirium often worsens at the time the patient would normally go to bed, a phenomenon known in hospitals as “sundowning.”


It's believed that delirium in the hospital setting occurs more frequently when certain risk factors are present.

The most likely causes of delirium include:

  • Preexistent Confusion or Cognitive Impairment: This broad category ranges from mild cognitive impairment to the early stages of Alzheimer's or other types of dementia and is a strong risk factor for delirium in hospital settings.
  • Drugs: The most common drugs associated with delirium are anticholinergic medications, such as those used to treat urinary incontinence. Benzodiazepines and opiates are also frequent contributors to delirium, however, antihistamines, antiepileptics, steroids, and some antibiotics can also be implicated.
  • Epilepsy: Studies show that a high percentage of patients in ICUs may be suffering from nonconvulsive status epilepticus—meaning they are almost constantly seizing without stereotypical convulsive limb movements. This can lead to cognitive impairments resembling delirium.
  • Lack of Oxygen: Difficulty breathing can result in a patient inhaling too much carbon dioxide or too little oxygen—both of which can contribute to acute confusional states. Obstructive sleep apnea is a risk factor.
  • Infection: Even mild viral infections can precipitate delirium. The most common are urinary tract infections, pneumonia, and skin infections.
  • Constipation: Retention of urine or stool is a frequent contributor to delirium. Bowel obstructions or perforations can do this as well.
  • Inflammation: Many factors, such as allergic reactions or post-surgical inflammation, can cause or contribute to acute confusional states.
  • Metabolic Issues: This includes thyroid problems, diabetes, renal failure, malnutrition, or an imbalance in stress hormones like cortisol.

Most patients with delirium have more than one of the above risk factors. Other common contributors include sleep deprivation, catheterizations, blood pressure dysregulation, multiple surgeries, alcohol use, depression, malnutrition, and impairment of vision and hearing. Strokes can be associated with delirium, although most of the time other signs of a stroke, such as weakness of an arm or leg, are also present.

Acute confusional states can serve as a warning sign that a patient is becoming seriously ill. If delirium is present in a hospitalized patient, a thorough evaluation of health and vital signs should be performed.


Blood tests, urine tests, and other diagnostics can help a doctor narrow down possible causes, but there are no definitive laboratory measures that can confirm a delirium diagnosis. Instead, a diagnosis of hospital-induced delirium is usually made upon evaluating a patient's history, symptoms, and mental functioning. Doctors can informally test a patient's mental state through conversation, or by conducting a more formal assessment of memory and perception. Additionally, a neurological exam can be performed to determine whether a stroke has caused the delirium.


Doctors may change or reduce a patient's medications to treat delirium, or they may introduce anti-psychotics or other psychoactive medications to control symptoms.

Additionally, several non-invasive interventions may help patients with delirium:

  • Promote good sleep and rest—providing eyeshades and earplugs can help a patient who is unable to sleep due to the constant light and activity in a hospital setting
  • Ensure the patient is adequately nourished and hydrated
  • Ensure the patient has access to items such as eyeglasses and hearing aids
  • Keep the person mentally active by reading to them, keeping them engaged in their treatment, and discussing current events


If a hospitalized loved one is suffering from delirium, try to remain calm while seeking help from a medical professional to evaluate symptoms and formulate a treatment plan. Hospital-induced delirium is usually temporary, but special care should be provided in order to reduce long-term consequences. Because delirium is associated with lengthened hospital stays, increased morbidity, and the development of dementia, steps should be taken to help mitigate the immediate and longterm consequences of delirium.

A Word from VeryWell

Delirium is frightening, but rarely permanent. Fortunately, there are many steps that medical staff and family members can take to help prevent delirium from getting out of hand while contributing factors are being addressed. Proper care of the patient can help ensure that everyone gets through the experience with as little discomfort or trauma as possible.

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Article Sources

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Additional Reading

  • Albrecht JS, Marcantonio ER, Roffey DM, et al. Stability of postoperative delirium psychomotor subtypes in individuals with hip fracture. J Am Geriatr Soc. 2015;63(5):970-6.

  • Johansson YA, Bergh I, Ericsson I, Sarenmalm EK. Delirium in older hospitalized patients-signs and actions: a retrospective patient record review. BMC Geriatr. 2018;18(1):43.

  • Rosen T, Connors S, Clark S, et al. Assessment and Management of Delirium in Older Adults in the Emergency Department: Literature Review to Inform Development of a Novel Clinical Protocol. Adv Emerg Nurs J. 2015;37(3):183-96.

  • Van velthuijsen EL, Zwakhalen SMG, Mulder WJ, Verhey FRJ, Kempen GIJM. Detection and management of hyperactive and hypoactive delirium in older patients during hospitalization: a retrospective cohort study evaluating daily practice. Int J Geriatr Psychiatry. 2018;33(11):1521-1529.

  • Zywiel MG, Hurley RT, Perruccio AV, Hancock-howard RL, Coyte PC, Rampersaud YR. Health economic implications of perioperative delirium in older patients after surgery for a fragility hip fracture. J Bone Joint Surg Am. 2015;97(10):829-36.