Older Persons Medicine Flashcards
(124 cards)
Postural hypotension is a common condition affecting around half of the elderly population living in a residential institution. How might it present?
Dizziness
Syncope (severe cases)
Falls
Fractures
Blurred vision
Nausea
Confusion
Weakness
Sometimes precipitated ie. by a cough, defecation
May occur several minutes after standing up
More frequent with:
Meals
Exercise
A warm environment
How is postural hypotension diagnosed?
Tilt-table testing can be used to confirm postural hypotension. Tilt-table testing involves placing the patient on a table with a foot-support. The table is tilted upward and blood pressure and pulse is measured while symptoms are recorded in various positions.
Lying standing blood pressure:patient should be lying for at least 5 minutes, taking the first BP and then standing to measure in the first minute and at 3 minutes.
A fall of 20mmHg or more in systolic blood pressure, or a fall of 10mmHg or more in diastolic pressure is significant
Causes of postural hypotension occur?
Neurogenic (autonomic failure):
Parkinsons Disease
Type 2 diabetes mellitus
Small cell lung carcinoma, monoclonal gammopathies, light chain disease, or amyloid
Non-neurogenic:
Drugs: antidepressants (TCAs), vasodillators, diuretics, negative inotropes, opiates, insulin
Dehydration
Sepsis or other states inducing vasodilation
Cardiac impairment (aortic stenosis, MI, CHF)
Chronic hypertension (loss of baroreceptor reflex)
Adrenal insufficiency (reduced intravascular volume)
How is postural hypotension managed?
Depends on cause
Ensure adequate hydration (blood volume)
In particular, evaluate polypharmacy
Reduce adverse outcomes from falls (e.g. fall alarm, soft flooring)
Behavioural changes (e.g. rising from sitting slowly, adequate hydration - avoiding high risk behaviours)
Compression stockings (reduce venous pooling)
In patients with enough cognition, counter-manoeuvres against postural hypotension can be taught (raising toes, raising legs, crossing legs)
Measures to expand blood volume include keeping the head of the bed elevated (reverse Trendelenburg). This increases plasma volume by decreasing overnight diuresis, with activation of the renin-angiotensin-aldosterone system
Pharmacotherapy:
Fludrocortisone (note: poor evidence base)
Midodrine (autonomic dysfunction)
What is the pathophysiology of postural hypotension?
Upon standing blood shifts from the chest to below the diaphragm
Fluid shift reduces venous return to the heart, and therefore ventricular filling and preload.
Cardiac output and therefore blood pressure are reduced.
The gravity-induced reduction in blood pressure is detected by baroreceptors in the aortic arch and carotid sinus.
Baroreceptors trigger baroreflexes, including vasoconstriction and compensatory tachycardia to restore BP.
Sympathetic outflow increases, vagal nerve activity decreases which decreases parasympathetic innervation to the heart.
The baroreceptors also send signals to the arterioles and venules in the circulatory system to increase total peripheral resistance.
Blood pressure increases.
In postural hypotension these mechanisms to maintain BP are impaired so there is a postural drop, because of one or more of:
- Failure of baroreflexes (autonomic failure)
- Volume depletion
- End-organ dysfunction
What factors may exacerbate postural hypotension?
Rising quickly after prolonged sitting or recumbency
Prolonged motionless standing
Time of day (early morning after nocturnal diuresis)
Dehydration
Physical exertion
Alcohol intake
Carbohydrate-heavy meals
Straining during micturition or defecation
Fever
What drugs may cause postural hypotension?
Diuretics
Alpha-adrenoceptor blockers for prostatic hypertrophy
Antihypertensive drugs,
Insulin, levodopa, and tricyclic antidepressants can also cause vasodilation and postural hypotension in predisposed patients
Why are the elderly more susceptible to postural hypotension?
- More prone to hypovolemia:
- Increase in natriuretic peptides
- Decrease in renin, angiotensin and aldosterone with age
- Impaired ability to retain water and sodium as well as diminished thirst response - Age related changes to CVS:
- Decreased baroreflex sensitivity with impaired alpha-1 adrenergic vasoconstriction and affected HR response
- Chronic HTN (further reduced baroreflexes and sensitivity and left ventricular failure compliance)
- Blunted response to the sympathetic nervous system recruitment in BP control - Health conditions
- Polypharmacy and medications that cause postural hypotension more commonly prescribed to the elderly ( furosemide and terazosin), use of multiple anti-HTN agents
- Higher prevalence of co-morbidities which cause autonomic dysfunction such as T2DM
- Deconditioning from lack of exercise leads to increased likelihood of experiencing severe symptoms from postural hypotension
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What are the overall aims of management of postural hypotension and how are they achieved?
1.To raise standing blood pressure without also raising supine blood pressure
2.To reduce orthostatic symptoms
3. To increase the time the patient can stand
4. To improve the ability of patients to perform activities of daily living
Achieved by targeting physiological mechanisms in order to:
1. Reducing venous pooling
2. Increasing blood volume
3. Increasing vasoconstriction
How does fludrocortisone work to treat postural hypotension? What are the contraindication and side effects, and how is it taken?
Fludrocortisone is a synthetic mineralocorticoid that expands plasma volume
This medication can be useful if non-pharmacological measures and cessation of exacerbating medications have proved unsuccessful. It has demonstrated good efficacy for patients whose plasma volume fails to adequately increase with salt and bolus fluids
Contraindicated in patients with failure, ascites and chronic renal failure.
Side effects may include supine HTN, severe hypokalemia,
Taken OD in morning starting at 100mcg
How does Midodrine work to treat postural hypotension? What are the contraindication and side effects, and how is it taken?
Midodrine is a vasopressor that is short-acting and can be useful in neurogenic postural hypotension.
It has a short duration of action and the literature suggests that it can be effective when used in conjunction with fludrocortisone. However, it is largely ineffective in patients with low plasma volume.
Caution in patients with severe HF, urinary retention and underlying HTN.
Midodrine has unique side effects including supine hypertension, scalp paraesthesia and pilomotor reactions, such as goosebumps.
Midodrine can be titrated for dosing up to three times daily, with a starting dose of 2.5mg.
Brief outline of the cardiac conduction system?
The electrical impulse travels through the heart via a specific conduction pathway. The sinoatrial node (SAN) acts as the initial pacemaker before the impulse spreads throughout the atria and towards the atrioventricular node (AVN).
The depolarisation wave travels through the heart’s septum via the Bundle of His and Purkinje fibres. These are organised into the left and right bundle branches.
The right bundle branch then depolarises the right ventricle and the left bundle branch depolarises the left ventricle simultaneously. The septum itself is depolarised by the left bundle branch, meaning the septum is depolarised from left to right.
What part of an ECG trace represents atrial depolarisation?
P wave
What part of an ECG trace represents conduction through the AVN and ventricles?
PR interval
What part of an ECG trace represents ventricular depolarisation?
QRS complex
What part of the ECG trace represents ventricular repolarisation?
T wave
How long is a normal PR interval?
0.12-0.20 seconds / 3-5 small squares
How long is a normal QRS complex?
Less than 0.12s / 3 small squares
How does Right Bundle branch block appear on ECG?
QRS > 120 ms (3 small squares)
RSR’ pattern in V1-V3
Wide, slurred S wave in lateral leads – I, aVL, V5-V6
(MaRoW)
How does Left Bundle Branch Block appear on ECG?
QRS duration > 120ms (3 small squares)
Dominant S wave in V1
Broad, monophasic R wave in lateral leads – I, aVL, V5-V6
Absence of Q waves in lateral leads
Prolonged R wave > 60ms in leads V5-V6
(WilLiaM)
What type of bundle branch block is ALWAYS pathological and how does it appear?
LEFT bundle branch block
QRS duration > 120ms (3 small squares)
Dominant S wave in V1
Broad, monophasic R wave in lateral leads – I, aVL, V5-V6
Absence of Q waves in lateral leads
Prolonged R wave > 60ms in leads V5-V6
What is seen here and what is the pathophysiology?
Right bundle branch block:
The sino-atrial node acts as the initial pacemaker
Depolarisation reaches the atrioventricular node
Depolarisation through the bundle of His occurs only via the left bundle branch.
The left branch still depolarises the septum as normal.
The left ventricular wall depolarises as normal.
The right ventricular walls are eventually depolarised by the left bundle branch, this occurs by a slower, less efficient pathway.
What is seen here and what is this pathophysiology?
Left bundle branch block:
The sino-atrial node acts as the initial pacemaker
Depolarisation reaches the atrioventricular node
Depolarisation down the bundle of His occurs only via the right bundle branch.
The septum is abnormally depolarised from right to left.
The right ventricular wall is depolarised as normal.
The left ventricular walls are eventually depolarised by the right bundle branch, this occurs by a slower, less efficient pathway.
What do blockages of the left bundle branches cause on ECG?
Anterior fascicle block, which is much more common, causes left axis deviation.
Posterior fascicle block may cause right axis deviation.
Blockage of both causes LBBB (left bundle branch block)