Flashcards in Geriatrics - Frailty and immobility Deck (15):
What is frailty?
This is defined as a state of increased vulnerability to poor resolution of homeostasis after a stressor event.
This increases the likelihood of adverse events - e.g. falls, delirium and disability
Outline the pathophysiology of frailty?
Frailty develops as a result of age related decline in multiple inter-related physiological systems which increases vulnerability to sudden health status changes triggered by apparently minor stressor events - e.g. medication change, minor illness.
Frailty is NOT simply the decline in physiological reserve with ageing. Frailty is an acceleration in this decline with failing homeostatic mechanisms.
It is likely that when multiple (not just single) physiological systems frail to an aggregate crucial level that frailty develops.
Key organs involved are: brain, endocrine system, skeletal muscle and immune system
How is the brain affected by ageing and frailty?
There is only limited cortical neuron loss with age, but neurons with high metabolic demand (e.g. hippocampal pyramidal cells) could be disproportionately affected by aged related synaptic changes etc.
Microglia are also affected. They become hyperesponse to small stimuli with ageing that could increase the risk of potential damage (i.e. delirium).
Frailty is known to increase the risk of cognitive decline, dementia and delirium.
What endocrine system changes occur in ageing that could be exacerbated in frailty?
Ageing is associated with decreased production of 3 circulating hormones:
1) GH: reduced growth hormone production by the pituitary leads to decreased insulin like growth factor (IGF) by the liver. IGF's are small peptides that increase anabolic activity in a number of cells types (and play a role in synaptic plasticity in neurones)
2) Reduced oestrogen and testosterone: lead to increased LH and FSH secretion (due to loss of negative feedback)
3) Adrenocortical cells: activity of these cells decreases with age leading to decreased levels of major sex hormone steroid precursors, accompanied by a steady rise in cortisol.
The exact consequences of these hormones is as yet unknown, but they may exacerbate neuronal age related changes.
How is the immune system affected by age?
There is a reduction in multiple immune cell types with age from stem cells to lymphocytes.
The senescent immune system may function adequately in the quiescent state but fails to respond to stress of inflammation.
The acute inflammatory response may also be hypersensitive and prolonged causing damage and frailty.
What changes occur to skeletal muscle with age?
Sarcopenia is the term given to age related changes in skeletal muscle mass, strength and power with age. This leads to decreased functional ability.
Are there any models that can be used to predict likelihood of frailty?
There are currently 2 predictive models of frailty:
1) Phenotype model - suggests that there is a frailty phenotype characterised by (i) unintentional weight loss, (ii) self reported exhaustion, (iii) low energy expenditure, (iv) slow gait speed, (v) weak grip strength. May allow detection of those at risk of frailty but clinical use as yet unknown
2) Cumulative deficit model - this forms the basis of the Canadian Study of Health and Ageing (CSHA) frailty index. Examined 92 baseline variables were used to define frailty. Frailty is defined as the cumulative effect of individual deficits - "the more people have wrong with them, the more frail they are". The original 92 variables have been reduced to 30
How common is frailty?
Frailty as a syndrome is very common. It is the leading cause of mortality in elderly patients.
Frailty increases with age and is more prevalent in women compared with men. There may also be some variation in specific populations.
How can frailty be assessed in patients?
There is currently no widely accepted standardised questionnaire to identify patients with frailty. But there are several assessment tools to help quantify frailty in those identified as at risk.
The "timed up and go test" is a hand grip strength test has been identified as a potential single measure assessment method for frailty. It has been incorporated into the Edmonton Frail scale which is a short, multi-dimensional test. However, the diagnostic accuracy of these tests have yet to be determined.
What is immobility?
Immobility is one of the most common presenting conditions in the frail and elderly along with falls (it is one of the geriatric giants). The important thing to remember is that immobility is NOT a diagnosis but a symptom of an underlying problem.
The history often gives clues as to the cause of the immobility, which can be regarded as sudden (e.g. NOF, fall) or progressive (e.g. PD).
How does a fall contribute to immobility?
Falls and immobility are closely linked. Adults who fall frequently become socially isolated and restrict their movements.
Typically, these patients resist standing and exhibit marked fall back when attempting to stand.
An important consequence of falls is fractured neck of femur and it is important whenever there is a history of recent falls to exclude a #NOF in a patient who is unable to walk.
What are the signs of a fractured neck of femur?
Painful, externally rotated short leg. This may not be obvious and x ray may be needed to confirm the diagnosis. Pain on weight bearing is also a useful sign.
How does stroke lead to immobility? What else should be considered?
Acute onset hemiparesis is usually accompanied by immobility to a greater or lesser degree. Patients with more diffuse cerebrovascular disease often experience gait abnormalities which can sometimes mimic PD. Remember that stroke is by definition sudden onset, and a clear history should help confirm the diagnosis.
Sometimes the history is of more insidious onset of arm or leg weakness. In this case, consider space occupying lesion or subdural haematoma.
Other causes of immobility...
1) Parkinson's disease
3) Visual impairment
4) Feet and footware
5) Misc (e.g. depression, dementia, urinary catheterisation)