Blood pressure (HTN and hypotension) Flashcards
What causes orthostatic hypotension ?
Results from failure of Baroreceptor responses to gravitational shifts in blood, when moving from horizontal to vertical position
Define what orthostatic hypotension is
This is a drop in SBP of at least 20 mmHg and/or a drop in DBP of at least 10 mmHg after 3 minutes of standing Think ‘3-2-1, drop’ - after 3 minutes of standing, a drop in at least 20 mmHg systolic or 10 mmHg diastolic
What symptoms may orthostatic hypotension cause ?
light-headedness dizziness blurring of vision, fainting and falls ‘Symptoms resolve as blood pressure returns to normal (for example, on returning to a seated position). and not all experience symptoms’
What are the causes of orthostatic hypotension?
It may be idiopathic OR may arise as a result of disorders affecting the autonomic nervous system (for example, Parkinson’s disease, multiple system atrophy or diabetic autonomic neuropathy), from a loss of blood volume or dehydration, or because of certain medications such as antihypertensives or alpha-blockers (e.g. for BPH). ‘On standing, gravity causes blood to pool in the lower extremities. The autonomic nervous system usually counteracts this by increasing heart rate, cardiac contractility and vascular tone.The skeletal muscle in the lower body also contracts to prevent excessive pooling.’
What happens to the risk of CV mortality with every 20/10 increase in BP?
The risk doubles
What is the normal range of BP ?
Between 90/60 and 140/90 mmHg.
What 2 categories can the causes of hypertension be split up into?
- Essential HTN - 90/95% of cases
- Secondary HTN may be caused by a wide variety of endocrine, renal and other causes.
What are the signs and symptoms of hypertension ?
Does not typically cause symptoms unless it is very high, for example > 200/120 mmHg.
If very raised patients may experience:
- headaches
- visual disturbance
- seizures
List the renal causes of secondary hypertension
- Glomerulonephritis
- Chronic pyelonephritis
- Adult polycystic kidney disease
- Renal artery stenosis
List the endocrine causes of secondary hypertension
- Primary hyperaldosteronism
- Phaeochromocytoma
- Cushing’s syndrome
- Liddle’s syndrome
- Congenital adrenal hyperplasia (11-beta hydroxylase deficiency)
- Acromegaly
List the other causes of secondary hypertension besides renal & endocrine causes
- Glucocorticoids
- NSAIDs
- Pregnancy
- Coarctation of the aorta
- Combined oral contraceptive pill
- Intracranial tumour
Define what essential hypertension is
This is a rise in BP (>140/90) of unknown cause
Define what hypertension is
- A clinic reading persistently above >= 140/90 mmHg, or:
- A 24 hour BP average reading >= 135/85 mmHg
How is HTN diagnosed ?
- Firstly measure BP in clinic, if the first reading is > 140/90 then take a second reading (the lower reading determines further management)
- Secondly diagnosis is then made using ABPM or HBPM (if ABPM declined or not tolerated)
How is HTN classified ?
Stage 1 (mild) hypertension:
- Clinic BP is ≥ 140/90 and
- ABPM or HBPM daytime average is ≥ 135/85
Stage 2 (moderate) hypertension:
- Clinic BP is ≥ 160/100 and
- ABPM or HBPM daytime average is ≥ 150/95
Stage 3 (severe) hypertension:
- Clinic BP is ≥ 180 or
- Clinic diastolic BP is ≥ 110
Note for severe dont need to do ABPM/HBPM and treated is started immediately
Why can you not rely on diagnosing HTN in clinic alone ?
Because of the subgroup of people with ‘white coat HTN’ - in these people there BP climbs by 20mmHg ==> people would be diagnosed with HTN when they actually have normal BP outwidth the clinic
How is ABPM performed ?
Ambulatory blood pressure monitoring (ABPM):
- At least 2 measurements per hour during the person’s usual waking hours
- Use the average value of at least 14 measurements
How is HBPM performed ?
Home blood pressure monitoring (HBPM)
- For each BP recording, two consecutive measurements need to be taken, at least 1 minute apart and with the person seated
- BP should be recorded twice daily, ideally in the morning and evening
- BP should be recorded for at least 4 days, ideally for 7 days
- Discard the measurements taken on the first day and use the average value of all the remaining measurements
When can you not use a automated blood pressure machine ?
If the persons pulse is irregular ==> you need to always check their pulse before and if its irregular then you need to do it manually
What is important to also asses in patients with newly diagnosed HTN?
Ensure they do not have any end-organ damage:
- Fundoscopy: to check for hypertensive retinopathy
- Urine dipstick: to check for renal disease, either as a cause or consequence of hypertension
- ECG: to check for left ventricular hypertrophy or ischaemic heart disease
- Take blood to measure glucose & HbA1c to check for DM, electrolytes, creatinine, eGFR, cholesterol
- Estimation of CV risk to discuss prognosis and healthcare options
What treatment should be provided to people with stage 1 HTN?
Lifestyle management:
- A low salt diet is recommended, aiming for less than 6g/day, ideally 3g/day.
- Caffeine intake should be reduced
- Other general bits of advice remain: stop smoking, drink less alcohol, eat a balanced diet rich in fruit and vegetables, exercise more, lose weight
Note - those with stage 2 or 3 HTN should also be given this lifestyle management alongside anti-hypertensives
When should patients with stage 1 HTN be offered more treatment than just lifestyle advice ?
Treat if < 80 y/o AND any of the following apply:
- Target organ damage
- Established CVD
- Renal disease
- Diabetes
- A 10-year cardiovascular risk equivalent to 10% or greater
This means starting them on anti-hypertensives
When should treatment with anti-hypertensives generally be started ?
ABPM/HBPM >= 150/95 mmHg (i.e. stage 2 or worse) - offer drug treatment regardless of age
When should anti-hypertensive treatment be started immediately after clinic measurement ?
If BP is ≥ 180/110 mmHg
For patients with any stage of HTN who are < 40 y/o what should be considered?
Specialist referral to exclude secondary causes.
What is the stepwise protocol for anti-hypertensive treatment of HTN?
1st line for those
OR 1st line for those > 55 or who are from afro-caribean origin = CCB (think C for carribean)
2nd line = if taking ACEi/ARB add either a CCB or thiazide diuretic. If already taking CCB add a ACEi or ARB (ARB preferred)
3rd line = ACEI/ARB + CCB + thaizide diuretic
4th line = if K+ < 4.5 add low dose spironolactone, if > 4.5 add alpha or beta blocker
What are the 2 main options for controlling someone’s BP in hospital if PO anti-hypertensives have failed ?
Can consider IV labetalol or GTN infusion
Define resistant HTN ?
This is HTn requiring 4th line treatment
How often should patients with HTN have there BP monitored and what should the BP targets be?
Anually using clinic BP measurements, with targets of:
- 140/90 mmHg in people aged < 80
- 150/90 mmHg in people aged ≥ 80
For people with a ‘white-coat effect’ consider ABPM or HBPM as an adjunct to clinic BP to monitor response to treatment. Aim for ABPM/HBPM target average of:
- below 135/85 mmHg in people aged < 80
- below 145/85 mmHg in people aged ≥ 80
