Up to 50% of older adults who undergo surgical procedures develop delirium.
Older adults are at heightened risk for this postoperative complication because of their reduced capacity for homeostatic regulation when they undergo anesthesia and surgery.
Postoperative the delirium manifests as acute, fluctuating failure of the brain to support normal arousal, attention, and organized thinking.
It is associated with delayed recovery from surgery and persistent neurocognitive disorders, as well as other adverse outcomes.
Also age-related changes in brain neurochemistry and drug metabolism increase the likelihood of adverse drug effects could precipitate delirirum.
Risk factors for postop delirium include age >65 years, dementia, poor vision, decreased hearing, severe illness, and infection.
Postop delirium can be missed or have a delayed diagnosis resulting in patients exhibiting behaviors that can compromise their safety, delay recuperation, and result in longer hospital stays, a greater financial burden, and increased morbidity and mortality.
Postop delirium has 3 subtypes, based on patient’s psychomotor activity:
Hyperactive delirium-patients exhibit heightened arousal, restlessness, agitation, hallucinations, and inappropriate behavior.
Hypoactive delirium-characterized by lethargy, reduced motor activity, incoherent speech, and lack of interest.
Mixed delirium-consists of a combination of hyperactive and hypoactive signs and symptoms.
Factors that increase postop delirium risk include:
age >65 years
existence of dementia
poor vision
decreased hearing
critical illness
infection.
Routine preoperative cognitive screening should be done.
To prevent postoperative delirium in high risk patients a program for delivering daily orientation, early mobilization, feeding assistance, therapeutic activities, and other measures are introduced help prevent delirium.
All patients who undergo surgery should receive daily delirium screening during the first postoperative week.
Causes of delirium include hypoxia, infection, dehydration, acute metabolic disturbance, and drug withdrawal.
Clinical features:
Acute onset and fluctuating course.
Inattention.
Disorganized thinking
Altered level of consciousness.
A positive screen for delirium requires the presence of acute onset and/or fluctuation and inattention, plus either disorganized thinking or altered level of consciousness.
If a patient who is exhibiting postop cognitive and/or behavioral disturbances has a reasonably accurate memory and a correct orientation for time, place, and person, interviews with the patient and caregivers will likely reveal potential causes for the behavioral problems.
Assessment for an underlying organic cause must be performed because specific treatment for the underlying diagnosis may improve delirium.
Risk factors include pre-existing cognitive dysfunction, postoperative pain, use of opioids and sedatives, and surgical inflammation.
Common causes of postoperative delirium include: hypoxia, infection, dehydration, acute metabolic disturbance, endocrinopathies, cardiac or vascular disorders, and drug or alcohol withdrawal.
Diagnostic evaluation may consist of serum urea, glucose, electrolytes, liver function tests, arterial blood gas analyses, urinalysis, nutritional evaluation, electrocardiogram, and a complete blood count.
Approximately 40% of cases of postoperative delirium are related to medication use.
Postop medications such as analgesics, sedatives, proton pump inhibitors, and others can cause delirium.
Medication-induced delirium is influenced by the number of medications taken, and with the use of psychoactive medications, and the specific agent’s anticholinergic potential.
Inadequate pain control in patients is more likely to result in delirium than patients who received more analgesia.
Severe pain significantly increases the risk of delirium postoperatively.
With the exception of meperidine, opioids do not precipitate delirium in patients with acute pain, except for meperidine.
Undertreating pain or administering very low, or excessively high doses of opioids is associated with an increased risk of delirium for both cognitively intact and impaired patients.
Constipation can contribute to the development of delirium, and preventing it in postop patients can reduce delirium risk.
Post operative delirium occurs in 50% of cardiac surgical patients and is associated with increased length of ICU stay, morbidity, mortality, and long-term cognitive decline.
Nonpharmacologic interventions are firstline treatment of postoperative delirium.
Such interventions can help patients develop a sense of control over their environment, which can help relieve agitation.
Environmental shifts contribute postoperative delirium, therefore avoiding transfers and securing a single room can be helpful.
Patients may experience altered perceptions, and view normal objects and routine actions of others as harmful and threatening.
Avoiding unnecessary sensory exposures, providing a nonthreatening cognitive/environmental and access to visual and hearing devices are encouraged to reduce risk of delirium.
Walking as soon as possible is encouraged.
All patients with delirium are at risk of falls, bit restraints are not recommended because they can exacerbate delirium and lead to injuries.
Pharmacologic treatment is reserved for patients whose behavior compromises their safety, and implemented only when the cause of the delirium is known.
Drug therapy aims to achieve safe and rapid behavioral control so the patient can receive necessary medical care, and to enhance functional recovery.
With hyperactive delirium, an antipsychotic typically is the treatment of choice because these medications are dopamine receptor antagonists, and excessive dopamine transmission has been implicated in this type of delirium.
Haloperidol often is the preferred treatment in a low-dose oral form.
A flexible family visiting program did not significantly reduce the incidence of delirium among patients in the ICU.
Benzodiazepines and other hypnotics and second-generation antipsychotics in older patients with delirium are avoided.
Most medications that modify symptoms of delirium can actually prolong the process.
It has been generally held the general anesthetic and sedative agents are implicated in postoperative delirium another neurocognitive disorders.
However, trials have recently shown that compared with general anesthesia, regional anesthesia in vulnerable older patients does not decrease postoperative delirium incidence, that the healthy human brain is resilient to even deep anesthesia, the decreasing general anesthetic concentration during surgery does not prevent delirium and general anesthesia in coronary artery bypass grafting leads to cognitive outcomes that are no different from percutaneous coronary intervention with minimal or no sedation.
These findings have been found in randomized trials of the effect of regional versus general anesthesia in patients requiring hip fracture surgical repair.
In a study of using electroencephalography to prevent excess dosing of inhaled general anesthetics during cardiac surgery for individuals older than 60 years, there was an 18% reduction in median inhaled anesthesia, dose, reduction of EEG suppression from 12 to 4 minutes, but no improvement in the 18% postoperative delirium rate (Deschamps A).