What is Postoperative Delirium?
Delirium is a brain condition caused by temporary disturbance in normal brain function due to health-related issues in another part of the body. It is a sign of critical brain dysfunction. The Diagnostic and Statistical Manual of Mental Disorders (DSM-5), a document produced by the American Psychiatric Association, provides guidelines for identifying and diagnosing mental disorders. To diagnose delirium according to DSM-5, symptoms must include noticeable changes in attention, thinking, or awareness that develop quickly and can change over time. It’s important to note that any changes in brain function should be different from the patient’s normal brain function. Experts have categorized delirium into three types: hyperactive, hypoactive, and mixed.
Post-operative delirium (POD), which can develop anytime between 10 minutes after anesthesia to up to a week in the hospital or until patient discharge, is often identified in recovery units after anesthesia as sudden, varying, and usually reversible changes in mental abilities, such as attention. Severe sleepiness or deep sedation shouldn’t be confused for changes in brain function. The most common type of POD is hypoactive delirium.
What Causes Postoperative Delirium?
Delirium, a state of mental confusion, can either be a worsening of an existing condition, or due to a new problem. There have been many attempts to identify what factors increase the risk of experiencing delirium after surgery.
According to DSM-5, a manual for mental disorders, delirium can be categorized into a few types: delirium due to drug misuse, withdrawal from substances, caused by medication, because of other medical conditions, or due to other reasons.
Delirium that happens after surgery (POD) is distinct and should be considered separately. This period is the time immediately following an operation until a patient is released from the hospital. Although POD shouldn’t be mistaken for the delirium that happens as someone comes out of anesthesia, it should be recognized if a person becomes aware and then falls back into delirium.
The causes of post-surgical delirium can be broadly divided into factors that exist before the operation, during the operation, and after the operation.
Before surgery, factors such as age over 65, being male, having cognitive issues or dementia, feelings of anxiety or depression, using sedative-type drugs called benzodiazepines, a range of vascular and neurological conditions, sense impairments, diabetes, high blood pressure, irregular heart rhythm, problems with electrolytes, alcohol misuse, lack of sleep, and smoking can contribute to the risk of post-surgery delirium.
During surgery, certain types of surgeries (specifically hip, cardiac, and vascular surgeries), emergency procedures, long-lasting surgeries, low blood pressure, shock, heart rhythm problems, body temperature abnormalities, and blood transfusions might increase the chances of experiencing delirium.
After surgery, causes can include low hemoglobin, low oxygen levels, intubation for a long time, pain, low protein levels, liver or kidney failure, and sleep disturbances.
It’s also a known fact that withdrawing from alcohol and benzodiazepines can lead to post-surgical delirium.
Risk Factors and Frequency for Postoperative Delirium
Postoperative delirium (POD) is a common condition that tends to occur more often after severe surgical procedures. Data shows that the occurrence of postoperative delirium can be between 15% and 54% in non-cardiac surgery patients, and even as high as 70% to 80% among patients in intensive care throughout their stay. For cardiac surgery patients, the incidence is also high, with a range of 26% to 52%.
However, it is challenging to get accurate figures for the incidence of POD because of the unclear difference between emergence delirium and postoperative delirium. Previous research has primarily concentrated on ‘hyperactive delirium’ which is a condition where a patient in the Post Anaesthesia Care Unit (PACU), might become agitated or start pulling at their tubes. This focus means that ‘hypoactive delirium’, the more common type, may be under-diagnosed. Hypoactive delirium is characterized by lethargy, decreased responsiveness and decreased activity level and is often missed if there isn’t regular delirium monitoring.
Bearing these challenges in mind, we know that the likelihood of developing postoperative delirium (POD) is greatly affected by the severity of the surgical procedure, the patient’s existing health conditions, and the use of sedative or pain relief medication.
Signs and Symptoms of Postoperative Delirium
Patients with this condition can show two types of symptoms. Some may exhibit exaggerated physical activity and serious mental disorder, which is referred to as the hyperactive variety. Others may display signs of apathy and sluggishness, which could be incorrectly attributed to the lingering effects of anesthesia; this is known as the hypoactive variety. Additional shared symptoms among patients often include changes in their state of awareness, confusion, and decreased ability to think or make decisions.
Testing for Postoperative Delirium
When checking for possible delirium, it’s important to first assess if the person can respond to voice. If they cannot, they are typically considered to be in a coma. After determining consciousness levels, specialists can assess the individual’s mental state, looking for signs of unusual changes or shifts in attention and consciousness.
The Richmond Agitation Sedation Scale (RASS) is a common tool to evaluate a patient’s level of consciousness. Patients in a deep sedation or who are unresponsive cannot be further analyzed for delirium.
According to the DSM-5 criteria, delirium involves the following characteristics:
- Impaired attention and orientation to environment.
- Occurs rapidly, often within hours or a few days, and varies in intensity throughout the day.
- Deterioration in cognitive functions such as memory, disorientation, language, and perception.
- These disturbances are not caused by other neurocognitive disorders or occur during a severely reduced level of consciousness, such as in a coma.
Delirium might be a result of another medical condition, medication, substance abuse, exposure to a toxic substance, or various causes – evidence for this can come from the patient’s medical history, physical examination, or lab tests.
There are several assessment tools for delirium that work well with different groups of patients in various hospital settings like post-surgery wards or intensive care units.
Some of these tools include the Confusion Assessment Method (CAM), Delirium Symptom Interview (DSI), Confusion Assessment Method for the Intensive Care Unit (CAM-ICU), and Intensive Care Delirium Screening Checklist (ICDSC).
Variants of CAM are often used. CAM-ICU and 3D-CAM are shorter versions of CAM that assess for delirium at a specific point in time. The Brief Confusion Assessment Method (bCAM) is validated for use outside of the ICU, while CAM-ICU is designed for intubated patients on mechanical ventilation.
The Delirium Detection Scale (DDS) and the Memorial Delirium Assessment Scale (MDAS) can help assess the severity of delirium.
Treatment Options for Postoperative Delirium
For people suffering from delirium, using non-drug related treatments early can help avoid long-term harm. These kinds of interventions have been proven effective. Good examples include programs like the Hospital Elder Life Program (HELP) and its modified version. These initiatives use many different professionals who help by reminding the patient where and who they are, improving their social interactions, visits from loved ones, having healthy meals and sleep patterns, reducing noise, providing help with hearing, sight etc. and encouraging movement early on. By using techniques such as daily reminders of where they are and who they’re with, oral and nutritional assistance and promoting activity early, it was found that these methods drastically reduced delirium.
In intensive care units (ICU), a strategy known as the ABCDEF bundle is associated with improved brain function. It involves assessing and managing pain, daily awakening and breathing practices, choosing suitable forms of sedation, regular delirium checks, and the careful use of medication. It also encourages mobility and family involvement.
This bundle has been shown to lead to better results for patients. For instance, they had more days where they were both alive and free of delirium, were independent quicker, and were able to go home sooner.
It’s crucial to immediately start orienting the patient in a post-anesthesia care unit, for example, by reminding them of their name, where they are, and the type of surgery they have undergone. Quick attention should also be given to physical discomforts like full bladder, difficulty breathing or issues with the patient’s position, and pain.
There are various medications used to prevent and treat delirium in patients at risk. If delirium continues, it’s important to deal with it quickly by reducing the continuing effects of anesthetic medicines. Drugs like flumazenil, naloxone, and physostigmine can be used to reverse the effects of sedatives, opioids, and muscle relaxants. Another medication, Haldol, can reduce the intensity of delirium episodes. However, it doesn’t affect the frequency and isn’t effective for prevention in the elderly population at risk.
Dexmedetomidine has shown to be useful alongside general anesthesia. This drug has been proven to lower the occurrence of postoperative delirium in the elderly, decrease agitation, nausea, and vomiting, and post-operative pain in children and ICU patients. It helps delirium resolve faster, reduces the need for other treatments, and results in a shorter ICU stay. However, the best way to use it during surgery isn’t yet known.
Certain drugs, including those that increase the availability of a molecule called acetylcholinesterase and some anti-psychotic drugs, do not seem to be more effective than placebo in treating delirium. Since sedatives like benzodiazepines are linked to delirium, propofol and dexmedetomidine are typically used for ICU sedation. Patients receiving dexmedetomidine were found to have lower and shorter delirium bouts than those receiving propofol.
What else can Postoperative Delirium be?
If you feel unwell, doctors need to consider a wide array of potential causes. These include problems like low oxygen levels (hypoxia), high carbon dioxide levels (hypercarbia), low blood sugar (hypoglycemia), being too cold (hypothermia), or suffering a stroke or seizure. They might also consider issues related to the nervous system (central cholinergic syndrome), high acid levels in the body (acidemia), problems with your body’s salts (electrolyte disturbances), or not getting enough vitamins and minerals (micronutrient and vitamin deficiencies).
The first things a doctor will do is to check your vital signs like heart rate and temperature, and measure the levels of oxygen, carbon dioxide, and sugar in your blood. They’ll also want to give you a full physical examination to help figure out what might be wrong and might perform a scan of your head if there are signs of possible brain-related problems.
Depending on what they’re seeing, the doctor might also ask for other tests. For example, if they know you’ve had problems with alcohol in the past, they might check for low levels of vitamin B1 in your blood, which can happen as a result of alcohol abuse. If your liver isn’t working the way it should, and there are signs of this when they examine you, they might want to do more tests to figure out why. In such cases, seeing high levels of certain substances in the blood, like lactate and pyruvate, and low levels of vitamin B1 can confirm the diagnosis.
What to expect with Postoperative Delirium
Postoperative delirium (POD) is linked with notably worse patient outcomes. There is growing evidence that POD could result in an increased chance of cognitive problems after surgery, prolonged brain dysfunction, early onset of dementia, and a faster decline in cognitive function in Alzheimer’s patients.
Patients displaying signs of delirium after surgery are not only indicative of ongoing brain dysfunction but may also face poorer cognitive performance at discharge and a higher likelihood of needing admission to a nursing or rehabilitation facility rather than returning home. Several studies have demonstrated a connection between delirium and a higher risk of death.
Possible Complications When Diagnosed with Postoperative Delirium
Postoperative delirium, or confusion after surgery, might increase the risk of inhaling food or liquid into the lungs, especially in emergency situations where patients weren’t able to avoid eating or drinking before surgery (referred to as “nil per os” or NPO guidelines). Postoperative delirium is connected with several negative outcomes:
- Longer stay in the hospital
- Raised medical expenses
- Higher chance of needing long-term care after being discharged
- Growing risk of disability
Preventing Postoperative Delirium
Improvements in sleep quality, better nutrition, plans for vision and hearing health, and training for medical staff have all been found to help reduce the chances of patients experiencing delirium.
