After hip surgery, one older person suddenly did not recognise their children the next day, said that someone was stealing, and made a noise all night once night fell. Family members often think the older person has developed dementia straight after surgery and do not know what to do. This is in fact known medically as postoperative delirium. It is an acute state of confusion that comes on after surgery, and it differs from dementia, which is a continuing decline. Most patients gradually get better as the body recovers. Many people overlook, however, that a key to preventing delirium is not medication alone but whether the patient can return to activity early.
Research shows that nurse-led non-drug interventions can reduce the incidence of delirium after surgery by about 26% in relative terms (RR 0.74), and also lower in-hospital mortality (Wang et al. 2024). Among these measures, getting out of bed early is an important one. This shows that preventing delirium does not have to rely on medication or passive waiting.
Understanding postoperative delirium and the risk factors in older people
Delirium is an acute state of fluctuating attention and awareness. It comes on suddenly and goes up and down (it is often worse towards evening and at night), and it is not an irreversible continuing decline. Because the two are handled very differently, carers must clearly tell postoperative delirium apart from dementia.
Postoperative delirium
- Comes on suddenly within hours to days after surgery
- Attention and awareness go up and down, and are usually worse towards evening and at night
- Mostly caused by anaesthesia, pain, infection, dehydration or an unfamiliar environment
- Usually fades within a few days to a week or two once the triggers are dealt with properly
Dementia
- Runs over months to years, starts slowly and gradually gets worse
- Memory and thinking ability decline continuously, and do not go up and down
- Caused by degenerative brain disease, and not by a single sudden event
- A long-term illness that needs long-term care and follow-up, and does not go away on its own
The reason older people are especially prone to delirium after surgery is closely related to frailty. Frail older people do not have enough physiological reserve and often cannot cope with the heavy stress of surgery and anaesthesia, which can trigger delirium. Research also shows that degree of frailty is an important predictor of postoperative complications and reflects surgical risk better than actual age (Lin et al. 2016). This explains why, among older people of the same age having surgery, some stay clear-headed as usual and others become severely confused. The key is often not age but fitness before surgery. To build physical reserve early, see the article on prehabilitation before surgery, which explains how to train the body before an operation.
Clinical research on non-drug interventions and early activity
When a patient has delirium, many people instinctively turn to sedatives or sleeping tablets. The main approach supported by clinical evidence is a set of non-drug interventions.
The "non-drug interventions" in the pooled analysis above are a package, in which returning to activity early is a key part that works together with the other measures.
In other words, the principle of preventing delirium is in line with the "early activity, avoid long bed rest" direction advocated by modern enhanced recovery after surgery (ERAS). Clinical research shows that putting an ERAS programme in place can on its own cut postoperative complications by about half (RR 0.53) and shorten hospital stay (Varadhan et al. 2010). Early activity therefore not only prevents pneumonia and clots but is also an important pillar in preventing postoperative delirium.
How early activity helps prevent delirium
Some may ask why moving the arms and legs should affect how the brain works. The mechanism is in fact quite direct. Long bed rest and bodily deconditioning themselves put older people at high risk of delirium.
The effect of long bed rest on the body and cognition
- Muscle strength is lost quickly. In healthy people, leg strength falls by about a tenth after only 5 days in bed (Wall et al. 2014)
- When the body stays still for a long time, blood pools more easily in the leg veins, raising the risk of clots
- Staying in bed and cut off from the outside world for a long time makes it easier to lose track of day and night and lose a sense of direction
- The weaker the body, the less it wants to move, and the less it moves, the weaker it gets
Benefits of early activity
- Keeps up muscle strength and balance, helping with self-care and lowering fall risk
- Daytime activity helps the brain tell day from night and recognise time and surroundings again
- Promotes venous return and reduces the complications of long bed rest
- Lets the older person regain the success of being able to move, which helps mood and sleep
It must be noted that "early activity" by no means means "the earlier and harder the better". It has to be done step by step, under the assessment of healthcare staff and the physiotherapist, according to wound healing and the degree of pain. Frail older people in particular need to go step by step, and this links closely with managing deconditioning and frailty in older people after surgery: dealing properly with deconditioning itself lowers the risk of triggering delirium. The reasons why modern medicine advocates getting out of bed as soon as possible after surgery are explained in detail in the article on ERAS and early mobilisation.
Home care advice and points to note
After an older person goes home from hospital, if there is still mild confusion, the cooperation of the carers at home is vital. Several practical and safe directions for care are given below.
The most practical things to focus on at home to guard against delirium:
- Draw out the rhythm of day and night—In the daytime, open the curtains, talk with the older person more, and encourage the person to sit up or walk a few steps. At night, dim the lights and keep quiet to help the brain tell day from night.
- Keep things familiar and steady—As far as possible arrange a fixed carer, put some personal belongings the older person knows well beside the bed, and remind the person of the date from time to time, to ease the unease caused by a change of environment.
- Senses and fluids—Put the glasses and hearing aids back on, and check whether the older person is drinking enough each day. If the body is dehydrated or the person cannot see or hear clearly, confusion gets worse.
- Find new triggers—Watch for fever, constipation, difficulty passing urine or worsening pain, because these can make delirium suddenly worse.
For local community resources, if family members are worried that the older person's confusion is not short-lived delirium, or want support with memory and cognition, they can call the Hong Kong Alzheimer's Disease Association (香港認知障礙症協會) (head office and memory clinic 2338 1120). For community rehabilitation and care services for older people after discharge, they can also go through a hospital referral or contact the District Elderly Community Centre in each district. This kind of community support can run alongside the daytime activity guidance of home physiotherapy, covering both cognitive support and the recovery of physical activity.
When should healthcare staff be contacted immediately? If the older person's confusion gets worse and worse, together with fever, severe pain, fast breathing, or such agitation that the person cannot be calmed at all, family members should not try to cope at home alone but should contact the treating medical team straight away or go to the accident and emergency department. During ordinary rehabilitation, Nova Health's registered physiotherapists can visit to assess the older person's mobility and home environment, help set up safe daytime activity habits, demonstrate the correct way to get out of bed and walk, and teach carers the danger signs of delirium to watch for, so that the older person can stay active safely at home. For the overall arrangements for home rehabilitation after discharge, see what to do after going home from hospital.
Finally, the limits of the clinical evidence need stating. Early activity is only one part of the "package" for preventing delirium, and exercise alone cannot guarantee that delirium will not occur. Because the causes of delirium are complex, problems such as the effects of medication, infection or electrolyte imbalance must all be dealt with together by healthcare staff. The physiotherapist's role is to firm up the pillar of "returning to activity early and safely", working together with other medical measures to keep the risk as low as possible.