Geriatrics Flashcards
6 renal/bladder changes with ageing
- Decreased kidney mass mainly due to cortical loss
- Decreased renal blood flow 10% per decade
- Reduction in max/min urinary osmolality
- Reduction in sodium conservation
- Increased detrusor hyperactivity
- Increased nocturnal polyuria (due to increased ANP in response to increase in intravascular volume)
Age related changes to adrenal hormones
- Basal renin and aldosterone decreased with constant ratio
- Stimulus response preserved but its magnitude is decreased
Age related decrease in aldosterone increases the risk of hyperkalaemia
Age related changes to the liver
- Decrease in volume and weight
- 35% reduction in blood flow which interferes with drug clearance
However no significant changes in LFTs with age
Albumin does not decline in WELL elderly
4 Age related changes to the cardiovascular system
- Decrease in maximum heart rate
- Resting heart rate and cardiac output largely unchanged
- Myocardial hypertrophy, increased LV wall thickness and L atrial size occurs with age
- Increased pulse pressure due to decreased arterial compliance and valve mobility
5 Age related changes to the lungs
- Decreased FEV1 and FVC
- Increased residual volume due to closure of terminal bronchioles in the dependent parts during tidal breathing
- Increased V/Q mismatching with rise in physiological dead space
- Blunted ventilatory response to decreased PaO2 and increasing PaCO2
- Diminished mucociliary clearance
5 endocrine changes in ageing
- Increased FSH/LH in both sexes
- Reduced GH
- Increased ADH with increased risk of hyponatremia
- Increased PTH with consequent increase in bone resorption
- Insulin resistance
Pharmacokinetic changes and ageing
Absorption is essentially unaltered, but distribution and clearance are significantly affected.
Distribution - reduced liver first pass metabolism, therefore peak drug level will be higher. Also, reduction in lean body mass with increase in fat leads to reduced Vd and increased concentration in water soluble drugs such as digoxin and alcohol, while as fat soluble drugs such as diazepam have greater Vd and prolonged half life.
Clearance is reduced due to age related decline in hepatic and renal function.
Define frailty.
What are its phenotypic features?
Distinctive problem of older people due to loss of reserve in multiple body systems with increased vulnerability to stressors and disease. At risk of catastrophic decline in health and function due to relatively mild illness.
Phenotypic features:
- Unintentional weight loss
- Reduced muscle strength
- Reduced gait speed
- Self reported exhaustion
- Low energy expenditure
Delirium mortality figures at 12 months and 5 years
6 risk factors for delirium from highest to lowest
12 months - 40%
Risk is greatest where delirium not associated with dementia.
5 years - 50%
RF:
- Cognitive impairment - RR 3-7
- Use of restraint 4.4
- Malnutrition 4.0
- Visual impairment RR 3.5
- Severe illness RR 3.5
- IDC RR2.4
Also hearing impairment and psychoactive drug use.
MMSE in diagnosis of dementia
Tests broad range of cognitive functions including orientation, recall, attention, calculation, language manipulation and construction praxis. But not effective for testing frontal/executive function
MMSE score <24/30 has poor sensitivity for AD, but good specificity at 96%.
Best used for AD, otherwise a good general screening test
Not good for assessing cognitive decline over time as people memorize the test.
Diagnostic features of probable AD
Insidious onset of symptoms with gradual progression.
Features include rapid forgetting and one other cortical manifestation (apraxia, visuospatial, executive, speech dysfunction)
No other physical signs/laboratory evidence of other causes of dementia.
Genetic causes of alzheimers dementia
Accounts for only <1%
Mutations in:
- Amyloid precursor protein - Ch21
- Presenilin 1 - Ch14
- Presenilin 2 - Ch1
Presenilin proteins form part of the gamma secretase which cleave APP to give amyloidogenic features.
CSF changes, PET scan changes, MRI changes precede clinical symptoms of AD by 10-15 years in persons at risk of dominantly inherited AD therefore these investigations may be useful (but not in sporadic AD which accounts for most of the patients)
Semegacestat which inhibits gamma secretase inhibitor was disappointing - doesnt work and has lots of side effects.
Role of apolipoprotein E in AD
Unclear how this gene causes AD, however E4 allele is a strong risk factor for AD especially with head injury with mean age of onset at 68 vs 84
Even then, 50% of homozygous E4 people are cognitively intact at age of 80
> 50% late sporadic AD have E4 allele.
Clinical features of vascular dementia
Early deficits involve attention, executive function and self monitoring.
Memory often is only mildly affected (which distinguishes it from AD)
Often early disturbance of gait which may look like PD but more apraxic features.
Important to note however that just because brain imaging shows ischaemic features, it does not exclude AD.
Clinical features of DLB
Rapid onset of progressive decline (faster than AD, 1-4 years vs 5-9 years).
Core features include fluctuating cognition, attention and alertness, recurrent visual hallucinations, spontaneous motor parkinsonism.
Important diagnosis to make as AChEI may be more effective and need to avoid neuroleptic meds need to be avoided.
Clinical features of FTD
Impaired personality and social conduct
Disinhibition, apathy, perseveration, stereotypy, hyperorality
Diverse groups including following subtypes:
- Behavioural subtype
- Semantic dementia (fluent)
- Primary progressive aphasia (non-fluent)
- Motor subtype (MND, PSP, CBD)
50% have family history.
Associated with MND.
Just like VaD, memory often preserved.
What is the role of MRI/FDG-PET imaging in dementia?
AD, DLB, FTLD have some characteristic features which distinguishes between them.
AD - generalized atrophy with decreased hippocampal volume, hypometabolism in precuneous and lateral parietotemporal cortex
DLB - generalized atrophy, hypometabolism in occipital cortex
FTLD - regional atrophy and hypometabolism of frontal/temporal areas.
Efficacy of cholinesterase inhibitors in dementia
Side effects of cholinesterase inhibitors
In mild-mod dementia, significantly enhanced retention of ADLs and may improve adverse behaviour and delay its onset.
Theoretically DLB more likely to benefit but good quality data lacking
No evidence in VaD, MCI (increased vascular death), FTD. Modest benefit of rivastigmine in PDD.
Increased GIT motility (diarrhoea, nausea, anorexia)
Vagotonic bradycardia
Exacerbation of asthma
Sleep disturbances and vivid dreams
MoA and efficacy of memantine
Neuroprotective NMDA antagonist which blocks glutamate induced neurotoxicity.
Studied in mod-severe AD/VaD, and as an add-on therapy in mild-mod AD.
Well tolerated (may cause seizures)
Used for MMSE 10-14 and as a monotherapy.
Risk factors for falls
Age
History of falls
ADL limitations
Impaired gait/mobility
Impaired sit-stand and transfers
Impaired visual contrast sensitivity
Impaired peripheral sensation
Impaired cognition
Stroke
Parkinsons disease
Psychoactive medication use
>4 meds
Management of stress/urge incontinence
General measures include:
- Pelvic muscle exercise - first line for stress incontinence
- Bladder retraining - gradually extend period between voids to increase bladder capacity
- Timing of oral fluids, reduce caffeine
- Treat constipation
- Weight loss
Urge incontinence - trial antimuscarinic such as oxybutynin, solifenacin if cognitively intact
Stress-incontinence in females - topical estrogen to help with urethral atrophy.
Mid-urethral sling surgery is effective as first line in stress incontinence, but NEED TO exclude URGE INCONTINENCE with urodynamic surgery before proceeding with surgery as it can be made worse.
Pathogenesis of delirium - key neurotransmitters involved
Acetylcholine - reduced. Hence this is the reason why people with alzheimers disease and anticholinergic agent usage can increase susceptibility to delirium
Dopamine - increased
Management of psychosis in Parkinsons disease
- Treat the underlying cause and cease contributing medications
- If these conservative managements do not resolve delirium, then stop parkinsons medications from least potent to most potent:
- Anticholinergics - eg benztropine
- Amantadine
- MAOB inhibitors (selegiline)
- COMT inhibitors - entacapone
- Dopamine agonist - pramipexole, cabergoline, apomorphine
- Levodopa
Association of BP and walking speed
Higher systolic BP was associated with increased risk of mortality only among elderly adults with medium to fast walking pace. In slower walking older adults, there was no association between elevated systolic or diastolic BP and mortality.
In slow walkers, elevated systolic and diastolic BP was actually independently associated with LOWER mortality risk.
Low diastolic pressure may contribute to high PP which is a strong risk factor for coronary events in elderly.
