S4: Disease Presentation in Older Adults Flashcards
List some variable we regulate in homeostasis
Variables in the body are regulated so that internal conditions remain stable and relatively constant.
- Temperature (thermoregulation).
- pH.
- Glucose.
- Water (osmoregulation).
- Electrolytes.
- Oxygen and carbon dioxide.
What mechanism is most commonly used in homeostasis?
Many homeostatic mechanisms use negative feedback loop, where a condition changes that is then detected. The correcting mechanism switches on and gets the variable back to its set point, once this is done the correcting mechanism turns off with a bit of delay. An example would be temperature (e.g. plasma osmolality too high, so we switch on ADH release, osmolality returns to normal and then we switch ADH release off, or things like thermoregulation).
Describe effect of age on homeostasis
As we age the efficiency of these control systems that maintain the internal environment become reduced. Naturally inefficient control mechanisms result in an unstable internal environment and when we are then exposed to external insult (e.g. cold) we are unable to maintain internal balance thus leading to increased risk of illness and leads to the physical changes we associate with ageing.
What is homeostenosis?
Homeostenosis is a phrase used that refers to diminished physiological reserve being available to meet challenges to homeostasis. In other words, with age the ability of our physiology to bring ourselves back to homeostasis decline and thus the level of insult our body can take is narrowed.
The endpoint of this gradual deterioration is frailty.
What is frailty?
Old age itself doesn’t mean someone is frail. Frailty is when there has been dysregulation of multiple physiological systems, especially in the stress response systems. This leads to increased vulnerability to disease, falls, institutionalisation, disability and death. In a frail person, small challenges to physiology e.g. it being cold, can overwhelm resources the person has and this can lead to illness.
Describe frailty thresholds
If a young person got a UTI, they would be able to deal with it without too much of a problem. However with an older individual who has frailty gets a UTI they are unable to cope with it as well and there is disturbance of internal environment and this leads to other symptoms.
- A person who is frail can therefore have the same presentation for different pathologies as the body is unable to cope with it. An example is delirium which may present with UTI, gastrointestinal bleeding or even a myocardial infarction.
- This occurs because in the older individual systemic responses to these differing illnesses may be similar involving catecholamines and mediators of inflammation that lead to the presentation (like delirium).
Thus in summary we can see that a loss of physiologic reserves in older adults leads to intolerance to challenges to their homeostasis.
- Someone with physical and cognitive frailty has poor function for a long period of time, whereas with cancer the individual has normal function for quite a while and then sees a rapid decline closer to death.
What organ ages that affects our water balance and osmoregulation?
The kidney changes as we age both anatomically and functionally and this can affect our water balance. RAAS and ADH controls osmoregulation.
Describe anatomical changes in ageing kidney
Anatomical changes include that there is a decline in renal mass mostly from the cortex, we also see an increase in renal fat and more fibrosis.
Also seen is sclerosis of cortical nephrons, these have long loops of Henle.
Describe functional changes in ageing kidney and how this affects osmoregulation
Functional changes seen with age include a decline in renal blood flow this is due to narrowing of larger arteries and intimal fibrosis. The mechanisms of the kidney involved in sodium excretion and conservation are impaired as well as a decline in the concentrating and diluting capacity of tubular fluid in the kidney. The ability to maximally dilute urine and excrete water is impaired. But we also see that the concentrating ability of the kidney is impaired, by:
- A decrease in the maximum osmolality they can get their urine (i.e. more watery).
- A decline in total body water (as peeing more).
- An diminished thirst response (increases risk of dehydration).However despite these ageing changes, in the absence of insult (e.g. dehydration, diarrhoea), the aged kidney will continue to maintain a normal fluid and electrolyte balance of the body. It is only when there is challenge to your physiology by insults that things go awry because you are unable to compensate as well if old.
- Going back to changes seen with age, the serum renin and aldosterone decline and there is impaired recovery of the kidney after insults, meaning that it isn’t as good at bouncing back after insult, rather it takes a hard hit.
Also a decline in GFR, this impacts on clearance and therefore drug dosing may have to be altered.
What are geriatric giants?
There are five common presenting problems that older people will turn up to hospital with when they are unwell, these are called the geriatric giants and are as follows:
1. Immobility.
2. Instability.
3. Intellectual impairment (e.g. delirium).
4. Incontinence.
5. (Iatrogenic) – not really a presenting complaint, rather how it got there.
Essentially the majority of problems that old people will present with will be rooted in one of the geriatric giants.
Describe Immobility in elderly
- ‘Can’t get up’, ‘can’t walk’, ‘feeling generally weak’, ‘can’t move’.
- Immobility is a common reason for referral to the doctors (from home by a family member or by a health visitor etc.). The question is why all of a sudden is there this reduced mobility, is it because of: acute or chronic illness, drugs, pain, delirium, sarcopenia, lack of a mobility aid or maybe even the wrong shoes.
- The cause does need to be identified and corrected if possible and they may require physiotherapy assessment.
- Consequences of immobility are serious and include: pressure ulcers, pneumonia, dependence (needing more assistance with daily living) and even death.
Describe Instability in elderly
- ‘I fell over’, ‘I tripped’, ‘I went down’, ‘my legs gave way’.
- This again is one of the most common reasons for presenting at the hospital, commonly due to falling over. 1/3rd of adults over 65 who live at home will have at least one fall a year and ½ of these will have more frequent falls.
- Causes of falling and this instability includes: drugs and alcohol related changes (e.g. gait changes, sarcopenia, visual impairment etc.), medical causes and environmental causes.
- Remember that the presenting complaint is not the diagnosis, rather the person fell due to a particular underlying reason (like those listed above).
- Consequences of a fall include: fractures (associated with a high morbidity), immobility, fear of falling, traumatic intracranial haemorrhage, dependence and death.
Describe intellectual impairment in elderly
- This is very common, may be described by relative as patient being “confused”, “muddled” or “not himself”.
About 20-30% of people in hospital have delirium but this is likely to be higher. - Focusing a bit more on delirium, it is defined as being a clinical syndrome characterised by disturbed consciousness, cognitive function or perception that has an acute onset and fluctuating course.
- Those over 65, with serious illness, dementia or a hip/femoral fracture are at increased risk of delirium.
- Precipitants of an episode of delirium include polypharmacy, illness, constipation, electrolyte or fluid imbalances, changes in the environment, seizure, pain etc. The list is massive.
- Consequences of delirium include instability, immobility, patient will need to stay longer in hospital or in critical care, dependence or even death.
Describe incontinence impairment in elderly
Incontinence not a normal part of ageing, the reversible causes of incontinence include (treatable):
- Delirium.
- Infection.
- Atrophic urethritis and vaginilitis.
- Pharmaceuticals.
- Psychiatric disorders esp. depression.
- Excessive urine output (e.g. due to heart failure or hyperglycaemia).
- Restricted mobility.
- Stool impaction.
- Consequences of incontinence include damage to skin, infection, feeling embarrassed, instability and social isolation
Mechanisms of heat loss
Heat is generated from cellular metabolism predominantly from the heat and liver, it is lost by mostly the skin and some from the lungs. The mechanisms of heat loss from the skin are four: Evaporation, Radiation, Conduction and Convection .
