[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anaesthesia and ICU](https://durgical.com/en/anaesthesia/) › [Recovery and pain](https://durgical.com/en/anaesthesia/areas/recovery/) › Postoperative delirium

# Postoperative delirium

- Concept

Some patients, especially older people, become confused and disoriented for days after surgery; it is often preventable and needs a search for its cause.

Updated Nov 13, 2026

## Key points

- Delirium is acute and fluctuating, with inattention plus disorganised thinking or altered consciousness (the basis of the Confusion Assessment Method).
- Hypoactive delirium is the most common type and is often missed or mistaken for depression or tiredness.
- Main risk factors: older age, pre-existing cognitive impairment or dementia, frailty, sensory deficits, alcohol use and polypharmacy.
- Multicomponent non-drug prevention (orientation, glasses and hearing aids, sleep, mobilisation, hydration, pain control, avoiding deliriogenic drugs) reduces incidence.
- Avoid benzodiazepines (except in alcohol or benzodiazepine withdrawal) and anticholinergics; antipsychotics only for severe distress or danger, briefly.

On this page

- The basics Key points
- What it is
- Key points
- How it works
- Step by step
- Delirium, dementia and emergence agitation
- In practice
- Next step
- Elsewhere in DurgiPedia

- Study Test yourself

- Connections Connections

## What it is

Postoperative delirium is an acute, fluctuating disturbance of attention and awareness, with disorganised thinking or an altered level of consciousness, that begins in the days after surgery, usually within the first three to five days. It is common after major surgery in older patients, especially after hip fracture and cardiac surgery, and it is linked to longer stays, falls, loss of independence, admission to care homes, later cognitive decline and death. Delirium results from a vulnerable brain meeting a precipitating insult. Predisposing factors include older age, dementia or cognitive impairment, frailty, poor vision or hearing, depression, alcohol misuse and many medicines. Precipitating factors include the stress and inflammation of surgery, pain, infection, hypoxaemia, hypotension, dehydration, electrolyte and glucose disturbances, urinary retention, constipation, sleep loss, and drugs such as benzodiazepines, anticholinergics and high opioid exposure; withdrawal from alcohol or sedatives can also cause it. Three motor types exist: hyperactive (agitated), hypoactive (quiet and withdrawn, the most common and most often missed) and mixed. Diagnosis is clinical and uses a validated tool such as the Confusion Assessment Method or the 4AT. Prevention with non-drug measures is the most effective approach; treatment means finding and correcting causes, and antipsychotics are kept for severe distress or danger.

## Key points

- Postoperative delirium differs from emergence delirium, which is agitation on waking from anaesthesia and usually settles within minutes to hours.
- It also differs from postoperative cognitive dysfunction, a subtler decline in memory and thinking found on testing weeks to months later.
- Screening of at-risk patients before surgery (a brief cognitive test) identifies those who need preventive measures.
- Delirium is a medical emergency in the sense that it signals an underlying problem: infection, hypoxaemia, a metabolic disturbance or a drug effect.
- Physical restraints and urinary catheters worsen delirium and should be avoided when possible.

## How it works

- Surgery triggers systemic inflammation, which reaches the brain and disturbs neuronal function in vulnerable patients.
- Imbalance of neurotransmitters, mainly reduced acetylcholine and excess dopamine, is thought to underlie the symptoms, which explains why anticholinergic drugs worsen delirium.
- Disrupted sleep and circadian rhythm, sensory deprivation and unfamiliar surroundings add to the brain's stress.
- The more vulnerable the brain, the smaller the insult needed: a minor infection can cause delirium in a patient with dementia.

## Step by step

- Identify at-risk patients before surgery and screen cognition — prevention works best when planned early.
- Apply non-drug prevention: orientation, glasses and hearing aids, day-night routine, early mobilisation, fluids and nutrition — these reduce incidence.
- Screen for delirium regularly with a validated tool such as the 4AT or the Confusion Assessment Method — hypoactive delirium is easily missed.
- If delirium is found, treat its causes: pain, hypoxaemia, infection, retention, metabolic and drug causes — the cause, not the confusion, is the target.
- Review and simplify the medicines — deliriogenic drugs are a common, reversible cause.
- Use supervision, not restraints; antipsychotics only briefly, for severe distress or danger — restraints and sedatives prolong delirium.

## Delirium, dementia and emergence agitation

| Feature | Postoperative delirium | Dementia | Emergence delirium |
| --- | --- | --- | --- |
| Onset | Acute, hours to days after surgery | Gradual, over months to years | On waking from anaesthesia |
| Course | Fluctuates during the day | Slowly progressive | Settles within minutes to hours |
| Attention | Impaired | Usually preserved until late | Impaired while agitated |
| Consciousness | Often altered (drowsy or hyperalert) | Usually normal | Agitated, not oriented |

## In practice

- Assess attention in every older patient after surgery: asking for the months of the year backwards is a simple bedside test.
- Look for causes in every case: pain, hypoxaemia, infection, urinary retention, constipation, dehydration, sodium and glucose levels, drugs and withdrawal.
- Review the drug chart and stop or reduce deliriogenic drugs (benzodiazepines, anticholinergics, sedating antihistamines, high-dose opioids) when possible.
- Good pain control reduces delirium; using fewer opioids through regional techniques and non-opioids helps.
- Involve the family: familiar faces, information about the patient's usual state and help with orientation.

## Next step

- Call the doctor responsible as soon as delirium is suspected: it may be the first sign of a complication.
- Ask for help from the geriatrics or psychiatry team for severe, persistent or difficult cases.
- Tell the family what delirium is and that it is usually temporary; ask for their help with orientation.
- Record the episode and its cause in the discharge summary: the patient is at higher risk in future surgery.
- Follow up cognition after discharge, because delirium can unmask or accelerate dementia.

## Test yourself

Think of the answer, then tap the question to see it.

## What are the key features of delirium in the Confusion Assessment Method?

Acute onset and fluctuating course, with inattention, plus either disorganised thinking or an altered level of consciousness.

## Which motor type of postoperative delirium is most common and why does it matter?

Hypoactive delirium; the patient is quiet and withdrawn, so it is often missed or mistaken for tiredness or depression.

## Why are anticholinergic drugs a risk for delirium?

Delirium is linked to reduced acetylcholine activity in the brain, so blocking muscarinic receptors worsens confusion, especially in older patients.

## How does postoperative delirium differ from emergence delirium?

Emergence delirium is agitation on waking from anaesthesia that settles within minutes to hours; postoperative delirium starts days later and fluctuates.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anaesthesia/postoperative-delirium/)

## Elsewhere in DurgiPedia

- [Mental status: orientation, attention and screening tests](https://durgical.com/en/clinical-exam/mental-status-orientation-attention-and-screening-tests/)
- [Comprehensive geriatric assessment: function, cognition, falls](https://durgical.com/en/clinical-exam/comprehensive-geriatric-assessment-function-cognition-falls/)
- [Nursing the older adult: functional assessment and geriatric syndromes](https://durgical.com/en/nursing/nursing-the-older-adult-functional-assessment-and-geriatric-syndromes/)
- [Physical restraints: a last resort and their safe use](https://durgical.com/en/nursing/physical-restraints-a-last-resort-and-their-safe-use/)
- [Promoting sleep in hospital](https://durgical.com/en/nursing/promoting-sleep-in-hospital/)
- [Decision-making capacity (competence) and how to assess it](https://durgical.com/en/medical-ethics/decision-making-capacity-and-how-to-assess-it/)

## Connections

## Related 6

- [The recovery unit: monitoring and discharge criteria](https://durgical.com/en/anaesthesia/the-recovery-unit-monitoring-and-discharge-criteria/)
- [The older patient](https://durgical.com/en/anaesthesia/the-older-patient/)
- [Delirium in the ICU: screening and prevention](https://durgical.com/en/anaesthesia/delirium-in-the-icu-screening-and-prevention/)
- [Postoperative pain: multimodal analgesia](https://durgical.com/en/anaesthesia/postoperative-pain-multimodal-analgesia/)
- [Premedication and aspiration prophylaxis](https://durgical.com/en/anaesthesia/premedication-and-aspiration-prophylaxis/)
- [Awareness and depth of anaesthesia](https://durgical.com/en/anaesthesia/awareness-and-depth-of-anaesthesia/)

## Related conditions 7

- [Delirium](https://durgical.com/en/conditions/delirium/)
- [Dementia (major neurocognitive disorder)](https://durgical.com/en/conditions/dementia/)
- [Mild cognitive impairment](https://durgical.com/en/conditions/mild-cognitive-impairment/)
- [Alcohol withdrawal and delirium tremens](https://durgical.com/en/conditions/alcohol-withdrawal-and-delirium-tremens/)
- [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/)
- [Hypoglycaemia (including insulin-induced)](https://durgical.com/en/conditions/hypoglycaemia/)
- [Acute urinary retention](https://durgical.com/en/conditions/acute-urinary-retention/)

## In Pharmacology 3

- [Haloperidol](https://durgical.com/en/pharmacology/haloperidol/)
- [Second-generation antipsychotics](https://durgical.com/en/pharmacology/classes/second-generation-antipsychotics/)
- [Dexmedetomidine](https://durgical.com/en/pharmacology/dexmedetomidine/)

[← All of anaesthesia](https://durgical.com/en/anaesthesia/)

Educational content; it does not replace supervised training, your institution's protocols or the anaesthetist's or intensivist's decision. It contains no doses and no ventilator or infusion settings.

Sources: [Postoperative Delirium](https://www.ncbi.nlm.nih.gov/books/NBK534831/) (StatPearls (NCBI Bookshelf), 2026).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/anaesthesia/postoperative-delirium/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anaesthesia/postoperative-delirium/