Confusion After Surgery: Understanding Postoperative Delirium
If someone you love has come out of surgery seeming muddled, agitated, unusually quiet, or just "not themselves," it can be frightening, especially if nobody warned you it might happen. This is called postoperative delirium, and it is one of the most common things doctors and nurses see in older surgical patients. You are not imagining it, and in most cases, it is temporary and treatable.
Delirium is a sudden change in attention and awareness that develops over hours to days and tends to fluctuate — someone might seem lucid in the morning and muddled by evening. It is different from dementia: dementia develops gradually over months or years, while delirium comes on quickly, usually has an identifiable trigger, and is generally reversible once that trigger is addressed. Someone with existing dementia is at higher risk of delirium, and the two can occur together, which is part of what makes it confusing for families to tell apart.
Reported rates vary depending on the type of screening used, but they are consistently high:
- Non-cardiac surgery: 15–54% of patients
- Cardiac surgery: 26–52% of patients
- Intensive care stays: up to 70–80% during the admission
In other words, this is one of the most common things clinical teams see after surgery in older patients, not a rare or unusual complication. Age over 65 is one of the main risk factors identified in the research.
Delirium is usually the result of several things stacking up at once rather than one single cause:
- Anaesthesia and other medications (especially sedatives and strong pain relief)
- Infection, anywhere in the body: including urinary tract infections, which are a very common trigger
- Electrolyte imbalance or dehydration
- Immobility: not being able to move around normally
- Poor sleep and an unfamiliar, overstimulating hospital environment
- Uncontrolled pain
- Pre-existing memory problems or dementia, and older age
There are two very different-looking presentations, and the quiet one is easy to miss.
- Agitation, restlessness, trying to pull out lines or get out of bed
- Seeing or hearing things that aren't there
- Rapid mood swings
- Withdrawn, unusually quiet, drowsy or slow to respond
- Easily mistaken for "just being tired" or low mood
- Actually the more common of the two, and more often missed without deliberate screening
- Stay present when you can, a familiar face is genuinely reassuring
- Bring in hearing aids, glasses, dentures and any other aids they normally use: sensory confusion makes delirium worse
- Bring familiar objects, photos, or a blanket from home
- Gently and calmly reorient them (where they are, why, what day it is) without arguing if they get it wrong
- Encourage gentle movement and normal daytime activity where possible, to support day-night rhythm
- Ask the team what's actually being checked: infection screen, blood tests for electrolytes, medication review, oxygen levels, bladder and bowel function are all common causes worth ruling out
Delirium itself is considered a situation that needs prompt clinical assessment to find and treat the underlying cause. It isn't something to just "wait out" at home if it develops after discharge. Seek emergency care immediately for:
- NIH / NCBI StatPearls, Postoperative Delirium. ncbi.nlm.nih.gov
- Health in Aging Foundation (American Geriatrics Society): Prevention and Treatment of Post-Operative Delirium. healthinaging.org
For a complete list of sources used across Postopcare.info, see our Sources page.
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