What is ICU Delirium?
Delirium, often called an ‘acute confused state,’ ‘toxic or metabolic brain disease,’ or ‘acute brain failure,’ is basically a rapid change in focus and awareness. These changes typically develop suddenly and can be accompanied by other cognitive problems like memory loss, disorientation, or disturbances in perception. Delirium is common, happening in about 20 to 70% of patients in a hospital.
An old and misleading term for delirium is ‘ICU psychosis,’ which was used mainly to describe overactive delirium in the intensive care unit (ICU). This term was commonly used when it was noticed that delirium was highly prevalent among ICU patients. Many studies have shown that delirium is even more common among ICU patients on breathing machines, affecting up to 80% of such patients.
Since delirium is the most frequently seen sign of sudden brain function issues in ICU patients, particularly among those on breathing machines, any new confusion in an adult patient should always be checked out. However, it’s important to accurately assess the situation because delirium can often be confused with other conditions. According to medical criteria, these new mental changes should not be due to a brain disorder that could explain the confusion, and they should not happen in a state of decreased consciousness (like a coma). Therefore, even if the exact cause of delirium isn’t found, a detailed evaluation for reversible causes is necessary. Delirium can be caused by a variety of things, ranging from substance misuse/withdrawal to serious neurological conditions like meningitis and stroke. The prevention, identification, and management of delirium are important for the patients’ health, both during hospital stay and after being discharged.
There are three categories of delirium based on patient behaviour:
* Overactive delirium
* Underactive delirium
* Mixed delirium
Overactive delirium is the type that is typically identified in patients outside of the ICU, but within the ICU, the underactive (24.5% to 43.5%) and mixed (52.5%) types are more common. Overactive ICU delirium, representing about 23% of cases, involves restlessness, agitation, emotional instability, and hallucinations that often hinder medical care. Older patients with new psychotic signs are unlikely to have a primary mental illness and should be assessed for a drug-related or physical cause. Underactive delirium typically involves confusion, sleepiness, apathy, slow movements, withdrawal, lethargy, and reduced responsiveness. This type of delirium often goes unnoticed and is linked with worse outcomes. Patients with underactive delirium often have a higher chance of death six months later compared to patients with other types of delirium. Mixed delirium is the most common, accounting for about half of all cases, and involves a mix of overactive and underactive features.
This writing focused on presenting the clinical features, evaluation, prevention strategies, and treatment of delirium among ICU patients. It also addressed the role of the medical team in assessing and treating critically ill patients with this condition.
What Causes ICU Delirium?
When trying to figure out what could be causing delirium (a condition characterized by sudden confusion and altered consciousness), it’s important to consider a wide range of factors. Some common causes of delirium can be:
* Infections
* The effects of alcohol or drugs, or withdrawal from them
* Wernicke’s disease
* Metabolic disorders
* Low blood sugar or “hypoglycemia”
* Certain medications
* Trauma or injuries
* Brain-related conditions
* Seizures
* Blood vessel issues
* Lack of oxygen or “hypoxia”
* Vitamin deficiencies
* Hormone-related conditions or “endocrinopathies”
* Exposure to toxins or heavy metals
There are also many risk factors that can make a person more likely to experience delirium. Some of these include:
* Being older
* Struggling with cognitive problems
* Having trouble seeing
* Abusing alcohol
* Struggling with a respiratory disorder
* Having a serious illness
* Having a terminal illness
* Having multiple health conditions or “comorbidity”
* Having an infection
* Undergoing major surgery, like complex abdominal, hip fracture, and heart surgery
A helpful way to remember the main causes of delirium is the acronym DELIRIUM:
D=Drugs
E=Eyes, ears, and other sensory deficits
L=Low O2 states such as heart attacks, strokes, and pulmonary embolism
I=Infection
R=Retention (of urine or stool)
I=Ictal state
U=Underhydration/undernutrition
M=Metabolic causes like diabetes and sodium abnormalities
In intensive care units (ICUs), the risk of delirium can be increased by:
* Already having dementia
* Needing a machine to help with breathing
* Sepsis
* A history of high blood pressure
* Being very sick when admitted
* Pain
* Stroke
* Psychiatric disorders and depression
* A traumatic brain injury
* Heart attacks
* Chronic obstructive pulmonary disease (COPD)
* Steroids
* High blood pressure
* Medications that affect the mind, including narcotics
* Deep levels of sedation
* Environmental factors, like not being able to see the sunlight
* Not being able to move around much and physical restraints
* Poor sleep quality
Other social factors, like abusing alcohol, smoking, and not having visitors, can also increase risk. Some types of medications like diphenhydramine, promethazine, and cyclobenzaprine, which have “anticholinergic” properties, can cause delirium as well.
Risk Factors and Frequency for ICU Delirium
Delirium, a sudden disturbance in mental function, is more common as people age. At home, about 1-2% of people are affected, but the numbers increase significantly in certain health care situations. For example, the rate of delirium jumps to 10% to 30% for elderly patients who come to the emergency room. Also, patients in the general medical unit have an even higher rate of 14% to 24%. This prevalence continues to rise in the intensive care unit (ICU), where 70% to 87% of the patients may experience delirium. After surgery, between 15% to 53% of older adults might experience delirium.
- At home, 1-2% of people experience delirium.
- In the emergency room, delirium affects 10-30% of elderly patients.
- For patients in the general medical unit, the prevalence is 14-24%.
- In the intensive care unit (ICU), delirium affects a whopping 70-87% of patients.
- Post-surgery, 15-53% of older adults may experience delirium.
Signs and Symptoms of ICU Delirium
Delirium entails a sudden and typically fluctuating change in an individual’s mental state that affects attention and cognition. The criteria defined by DSM-5 suggest that such cognitive changes can’t be attributed to pre-existing or developing neurocognitive disorders, e.g., dementia, or effects of sedation or coma.
Typical methods of assessing a person’s orientation in terms of who they are, where they are, their understanding of their situation, and their awareness of time may not be sufficient in assessing delirium. This is because a person could still experience delirium while appearing aware of these aspects. The duration of delirium can range from several days to even months. Additional symptoms of delirium may include delusions or hallucinations (positive psychotic symptoms), confusion, tiredness, and sleepiness.
A detailed neurological and physical examination should be conducted when diagnosing delirium; such an examination can provide clues to its cause. For instance, a fever might point to an underlying infection, while specific neurological deficits could indicate a neurological or vascular issue as the source of the delirium.
A comprehensive review of the patient’s history might also uncover significant clues. For example, history of substance or alcohol misuse could suggest intoxication, withdrawal, or even vitamin deficiency as a potential cause of delirium.
Testing for ICU Delirium
For patients, it’s important that doctors carefully review their health history and conduct a physical examination before deciding which tests should be carried out. Some of these potential tests could include:
– Regular lab checks
– Tests to determine if an infection might be present, such as urinary tract infection or meningitis
– Tests to check for imbalances in the body chemistry, such as low blood sugar, electrolyte levels, or high ammonia levels
– Tests to check for possible substance abuse or withdrawal symptoms
– Tests to identify any issues with the brain or blood vessels using imaging
– Tests to spot any vitamin deficiencies
– Tests investigating any potential hormonal disorders (also known as endocrine disorders).
Treatment Options for ICU Delirium
When monitoring Intensive Care Unit (ICU) delirium, two extensively validated and widely used methods are the Confusion Assessment Method-ICU (CAM-ICU) and the Intensive Care Delirium Screening Checklist (ICDSC). These methods help assess a patient’s attention, orientation, and memory, and can be used by non-psychiatric ICU staff. They’re performed even if the patient can’t speak due to an endotracheal tube in their windpipe.
CAM-ICU has two steps involving the use of a sedation scale like the Richmond Agitation-Sedation Scale (RASS). It measures the patient’s level of consciousness from calm and alert (0) to deep coma (-5). Those who aren’t in a deep coma are evaluated for delirium symptoms such as an altered mental status, lack of attention, disjointed thinking or a change in their consciousness level.
The ICDSC evaluates an individual’s level of consciousness on a scale ranging from unresponsive to an exaggerated response. Patients who respond only to intense and repeated stimulation aren’t further assessed. Otherwise, they’re checked for changes during the previous 24 hours, and a score of 4 or above indicates delirium.
Beyond these specialized methods, regular clinical evaluations are essential and may include routine checks for vital signs or neurological status.
When it comes to managing delirium, there’s no universally accepted treatment that has been proven to decrease its duration. So, the focus is usually on addressing the underlying condition causing the problem. Additional tactics may include treating any abnormal electrolyte levels, avoiding medicines that could worsen delirium, maintaining a regular sleep schedule, managing pain and other sensory issues, and encouraging patient mobility and family visits.
Several medications, like antipsychotics, may be used to manage the symptoms, but the effectiveness of these varies widely. To ensure patient safety, it’s important to monitor potential side effects, such as heart-related issues or neurologic disturbances.
Non-drug interventions might include behavioral strategies, such as orienting patients to their surroundings, occupational therapy, and patient and family training. Early mobility exercises in the ICU may help speed up recovery and reduce the duration of delirium. Using restraints should be considered as a last resort and should be used for the shortest possible time.
Preventing delirium is as important as treating it. Studies show that patient-centered approaches aimed at reducing risk factors can possibly lower the incidence of delirium. These methods may involve addressing cognitive impairment, improving sleep, promoting mobility, or optimizing vision and hearing. Additionally, preventing potential triggers such as infection, dehydration, constipation, and lack of oxygen is critical. For ICU patients at risk of developing delirium, dexmedetomidine infusions may help reduce its prevalence.
Lastly, various strategies, such as the mnemonic ABCDEF bundle or the UNDERPIN-ICU protocol, have been suggested for evaluating and preventing delirium. These interventions aim at managing key risk factors for delirium, including cognitive impairment, sleep deprivation, immobility, visual and hearing impairment.
What else can ICU Delirium be?
Delirium can be a difficult condition to diagnose because there are other conditions that have similar symptoms. This means it requires careful medical evaluation and routine monitoring to rule out other possible diagnoses. Here are some of the conditions that could be mistaken for delirium:
- Neurocognitive disorders
- Mental illnesses like brief psychotic disorder, schizophrenia and related conditions
- Mood disorders that cause psychosis, such as severe episodes of bipolar disorder or depression
- Acute stress disorder
- Conditions where symptoms are intentionally faked or exaggerated, referred to as malingering and factitious disorder
It’s essential for healthcare providers to conduct thorough examinations and tests to accurately identify delirium and not misdiagnose it as any of the above conditions.
What to expect with ICU Delirium
Patients with delirium typically stay longer in the hospital, and their survival rate after six months is lower compared to patients who don’t have delirium. Moreover, delirium can result in long-lasting mental issues for patients who manage to overcome a critical illness.
Possible Complications When Diagnosed with ICU Delirium
Delirium, or abrupt changes in the brain that cause mental confusion and emotional disruption, can lead to a bunch of complications for patients in the hospital. For example, it can increase hospital costs, introduce more health problems, and increase the likelihood of death. A recent research analysis also showed that this condition can even lead to long-term cognitive (brain function) decline in both surgical and nonsurgical patients.
Patients in critical condition who develop delirium may face many complications such as:
- Increased risk of death
- Longer requirement for mechanical ventilation (breathing support)
- Extended stays in the Intensive Care Unit (ICU)
- Higher chances of accidentally removing catheters, breathing tubes, and urinary tubes
- Increased likelihood of getting readmitted to the ICU
- Higher risk of cognitive impairment after leaving the ICU
Also, the cost of healthcare tends to rise due to these complications.
