Pediatric Hypertension

Question 1

What is blood pressure?

Answer 1

It is the force exerted by blood against any unit area of the vessel wall. (P=F/A)

It is Cardiac Output x Total Peripheral resistance or Heart rate x Stroke Volume x Total Peripheral resistance.

Question 2

How is the Direct Intra-arterial measurement of BP carried out?

Answer 2

A catheter is paced into the vessel and the bp is measured in line with the vessel (end-on pressure). This method is employed by physiologists and intensivists

Also used to measure the central venous pressure (line passed into the svc to measure the pressure of the right atrium) and intra-cranial pressure in clinical practice.

Question 3

How is the auscultatory method for measuring BP carried out?

Answer 3

A sphygmomanometer (mercury, arenoid or digital) and a stethoscope is used.
This method is the gold standard for clinical practice.

K1 & K5 sounds are measured for the systolic and diastolic sounds respectively.
The values obtained are lower than those for the direct and oscillometric methods.

Question 4

How is the palpation method (flush technique) for measuring BP carried out?

Answer 4

It involves the use of a sphygmomanometer and a palpating finger. It is largely unreliable.
It only measures systolic - K1 pressures.

The palpated pressure is generally 10mmHg below K1.

Question 5

How is the oscillometric method for measuring BO carried out?

Answer 5

It involves the use of a sphygmomanometer and a monitor (eg. digital BP device, dana map).

Oscillations which represent pulsatile blood flow through arterial wall are transmitted to a cuff encircling the extremity.

K1 - Recorded at the point of rapid increase in oscillation amplitude.
K5 - Recorded at the point of sudden decrease in oscillation amplitude.

Values obtained are slightly higher than those in auscultatory method.

Question 6

How does the Doppler Ultrasound technique for measuring BP work?

Answer 6

The Doppler ultrasound is placed over the pulse to magnify the sound so that it’s audible without a stethoscope.

Sound detected is 5mHg higher than K1.

Question 6

How does the Doppler Ultrasound technique for measuring BP work?

Answer 6

The Doppler ultrasound is placed over the pulse to magnify the sound so that it’s audible without a stethoscope.

Sound detected is 5mHg higher than K1.

Question 7

How does the Doppler Ultrasound technique for measuring BP work?

Answer 7

The Doppler ultrasound is placed over the pulse to magnify the sound so that it’s audible without a stethoscope.

Sound detected is 5mHg higher than K1.

Question 8

How are ambulatory BP measurements carried out?

Answer 8

Multiple measurements are recorded over time (e.g. a 24 hour period) using a digital device strapped to the patient’s limb as he carries out regular activities outside the hospital.

The results are analyzed on a computer or paper tracer in-built in the device using the mean of the readings.

It gives a truer picture of bp trends.
It is used to diagnose white coat hypertension and nocturnal hypertension (absence of normal physiological drop in bp during sleep.)

Question 9

What is the definition of HTN in adults?

Answer 9

It is an epidemiological definition based on the risk of adverse events (e.g. stroke) - >140/90 mmHg.

Question 9

What is the definition of HTN in adults?

Answer 9

It is an epidemiological definition based on the risk of adverse events (e.g. stroke) - >140/90 mmHg.

Question 9

What is the definition of HTN in adults?

Answer 9

It is an epidemiological definition based on the risk of adverse events (e.g. stroke) - >140/90 mmHg.

Question 10

What is the definition of HTN in adults?

Answer 10

It is an epidemiological definition based on the risk of adverse events (e.g. stroke) - >140/90 mmHg.

Question 11

What is the definition of HTN in adults?

Answer 11

It is an epidemiological definition based on the risk of adverse events (e.g. stroke) - >140/90 mmHg.

Question 12

What is the definition of HTN in children?

Answer 12

A definition statistically based on normative data - >/= 95th centile for age, gender and height.

By this statistical definition, 5% of normal children will be classified as hypertensives,

Question 13

What are the other definitions for HTN in children?

Answer 13

Normal BP - < 90th centile for age, gender and height
Pre-HTN - 90th - <95th centile for age, height and gender
HTN stage 1 - 95th - 99th centile + 5mmHg
HTN stage 2 - >99th centile + 5mmHg

Question 14

How is the BP centile plotted?

Answer 14

The height centile is determined first. If it falls between 2 centiles, the closest one is used, otherwise the lower height centile is used.

Question 15

What is hypertensive emergency?

Answer 15

Acutely elevated BP with evidence of threatening end organ damage involving the following organs
Brain - Severe headache, visual changes, Cranial nerve palsy, Papilledema.
Heart - Acute chest pain, tightness, breathlessness.
Kidney - Decreased urine output (acutely), proteinuria or hematuria on dipstick

Symptomatic, Severe HTN.

Question 16

What is Hypertensive Urgency?

Answer 16

Severe hypertension without evidence of threatened end organ damage or symptoms.
BP treated urgently but not aggressively like in hypertensive emergency so as to prevent progression to hypertensive emergency.

Patient should be managed as in-patient if possible.

Question 17

What are the 7 rules of correct BP measurements according to Antwi?

Answer 17

Select the right cuff size - The length of the inflation bladder should be at lease 80% of the MUAC and the width of the inflation bladder should be at least 40% of the MUAC.

Child rests for at least 5 minutes in comfortable environment and position. Arm rests on surface and supported at heart level (reference level - values outside this are higher) with the lower edge of the cuff 2 cm above the cubital fossa.

Bell of stethoscope used.
Bladder tubings must lie over the brachial artery. Adhesive side of the cuff shouldn’t touch skin.

K1 and K5 used for systolic and diastolic respectively.
Multiple measurements are made (pref at different settings and the lowest reading taken. 3 measurements are taken and an average of the last 2 used for research purposes.

Question 18

What are three things you must know in the technique of bp measurements

Answer 18

Leg BP readings are 10-20mmHg higher than the arm pressure in any person.

If the reverse is seen, think aortic coarctation distal to ductus arteriosus.

Inflating bladder for too long -> leads to venous pooling.

Question 19

In which conditions (11) should you suspect hypertension in a child?

Answer 19

*Alteration in consciousness including aggressive behaviour and convulsion
*Oedematous
*Known kidney disease or evidence of abnormal urinalysis
*Heart failure
*Obesity
*Failure to thrive
*Stroke or other palsies including cranial nerve palsy
*History of Low Birth weight (small number of nephrons)
*Unexplained anaemia, or blurred vision
*Neurofibromatosis
*Other syndromes like Turner & Williams.

Question 20

How would you describe the aetiology of childhood hypertension?

Answer 20

Of secondary cause until proven otherwise.

Particularly so among the very young, and in the severely hypertensive.

Majority (~ 80%) are of renal origin)

The number of children with essential hypertension is on the rise - particularly among obese adolescents with or without family history.

Question 21

What are the broad causes of childhood hypertension?

Answer 21

Renal disease
Vascular disorders - the younger the child with htn, the more likely to be a vascular malformation like renal artery stenosis, coarctation of the aorta.
Endocrine causes
Neurologic causes
Renal tumours
Catecholamine-secreting tumours
Drug induced
Miscellaneous causes

Question 22

What are the congenital causes of hypertension in a Neonate to 1 year old?

Answer 22

Congenital lesions of the vasculature - Renal artery stenosis, Coarctation of the aorta
Congenital lesions of renal parenchyma - Polycystic kidney disease, Dysplastic kidneys, Obstructive uropathy
Congenital adrenal hyperplasia - 11B - hydroxylase deficiency, 17 -a hydroxylase deficiency

Question 23

What are the acquired causes of hypertension in a Neonate to 1 year old?

Answer 23

Renal artery/vein thrombosis, 2 umbilical artery/vein catheterization
Bronchopulmonary dysplasia
Medications - Theophylline/caffeine, Phenylephrine & END in cold medications, steroids, vitamin D intoxication
Total Parental nutrition (High Ca2+)
Maternal drug use - Cocaine/heroin
Scar Kidney from UTI
Wilms tumor -or any other kidney tumor that produces renin
Pheochromocytoma - Produces epinephrine

Question 24

What are the causes of HTN in the 1-5year age group?

Answer 24

Renal; artery stenosis
Glomerulonephritis
Renal vein thrombosis
Wilms tumor - Produces renin
Neruroblastoma - produces epinephrine
Phaechromocytoma
Cystic kidney disease
Monogenic HTN (e.g. Liddle’s syndrome)

Question 25

What are the causes of HTN in the 5-10year age group?

Answer 25

Glomerulonephritis
Renal scars from reflux nephropathies/UTIs
Renal artery stenosis
Cystic Renal Disease
Endocrine tumours
Essential HTN
Obesity

Question 26

What are the causes of HTN in the 10-20year age group?

Answer 26

Obesity - 1 hypertension, in patient’s with familial connection)
Essential HTN
Reflux nephropathies with repeated UTIs
Glomerulonephritis
Renal artery stenosis
Endocrine tumours
Hyperthyroidism
Drugs (ocp, Illicit drugs)

Question 27

How is a hypertensive child clinically evaluated? Patient’s history

Answer 27

Symptoms of renal disease (haematuria, oliguria, evidence of bodily swelling, polyuria, enuresis)
Symptoms of vasculitis/rheumatology (Joint swelling & rash)
Past medical history (Umbilical artery /vein catheterization, previous renal disease e.g. previous swelling)
Drug history (Steroids, ocp, amphetamines, other illicit drugs)
Birth history - Low birth weight
Family history - Hypertension

Question 28

What clues can be found in the physical examination of a child with hypertension?

Answer 28

Femoral artery delay or imperceptible or BP discrepancy between the arm and leg -. coarctation of aorta, Takayasu arteritis
Cafe au lait spots - Neurofibromatosis
Abdominal bruit -> Renal artery stenosis, Takayasu arteritis
Ambiguous genitalia - Congenital adrenal hyperplasia
Dysmorphism suggestive of Turner (have coarctation of aorta) or William Syndromes
Signs of Chronic Renal failure - Growth failure (Stunted), renal rickets, anaemia, oedema
Beside urine dipsti8ck positive for protein & blood with or without oedema - glomerulonephritis
4 limb BP - BP in upper limbs greater than BP in lower limbs.
Brain tumours

Question 29

What is the rationale behind investigations for childhood hypertension?

Answer 29

It’s two fold - to define aetiology and to assess the presence of end organ damage

Question 30

What investigations are carried out for childhood hypertension?

Answer 30

FBC
Urine dipstick + microscopy +/- culture
BUE , SCr, Ca, Mg, PO4, Blood gases
Uric acid
Kidney, Ureter, Bladder ultrasound, + Doppler studies to R/O Renal artery stenosis

Question 30

What investigations are carried out for childhood hypertension?

Answer 30

FBC
Urine dipstick + microscopy +/- culture
BUE , SCr, Ca, Mg, PO4, Blood gases
Uric acid (damages the endothelial lining of the vessels, leading to clot formation, hypertension)
Kidney, Ureter, Bladder ultrasound, + Doppler studies to R/O Renal artery stenosis

Question 31

What investigations are carried out for childhood hypertension (b)?

Answer 31

Chest X Ray for cardiomegaly
Echo for Left ventricular hypertrophy (end organ damage)
Fundoscopy
Plasma renin activity (PRA) for RAS & renin secreting tumours)
Pre/Post captopril nuclear scan

Question 32

What investigations are carried out for childhood hypertension (c)?

Answer 32

MRA / CT angiogram
DMSA (Dimercaptosuccinic acid) scan for renal scars
Urine HVA & VMA for catecholamine secreting tumours/MIBG(Iobenguane) scintigraphy
Serum aldosterone and K (Lower than aldosterone)

Question 33

What is the role (implication) of uric acid in the pathogenesis of HTN in children and adults?

Answer 33

Causes endothelial dysfunction leading to microvascular and inflammatory injury to the kidneys.

There is reduced levels of endothelial derived NO an associated elevation of RAAS.

Elevated uric acid levels in hypertensive individuals is associated with adverse outcomes like stroke.

Question 34

How are individuals with adverse effects of uric acid (and HTN) treated?

Answer 34

Allopurinol is used.

Question 35

What are the complications of childhood hypertension?

Answer 35

Hypertensive encephalopathy
Left Ventricular failure
Stroke
Subarachnoid hemorrhage
Secondary renal damage
Retinopathy
Vasculopathy

Question 36

Describe the non-drug therapy of childhood hypertension

Answer 36

Reducing salt intake
Weight reduction for obesity related hypertension
Intake of more vegetables on account of K-richness.

Question 37

What are the principles of anti-hypertensive drug therapy

Answer 37

Long-acting (once daily medication)
Maximize treatment dosage before adding on

Question 38

What agents are used in the drug therapy of childhood hypertension?

Answer 38

Ace Inhibitor and ARBs (Avoid if RAS suspected or in hypovolemia)
Beta-blocker
Calcium channel blocker
Diuretic
Every other drug (methyl dopa, alpha blockers, vasodilators like hydrallazine)

A + B drugs are not combine for the purpose of BP control. Rather A +C +D or B+ C+ D

Question 39

What is hypertensive encephalopathy?

Answer 39

Hypertension with changes in mental status and/or seizures.

Question 40

What are other manifestations of hypertensive encephalopathy?

Answer 40

Facial palsy
Visual changes - blindness
Coma

Question 41

What is the pathophysiology of hypertensive encephalopathy?

Answer 41

Disruption of the normal autoregulatory mechanisms of cerebral blood flow (inability of cerebral vasculature to constrict appropriately in response to abrupt increase in cerebral blood flow, resulting in cerebral hyperperfusion (cerebral edema).

It comes at the back of acute bp rise. In children with nephritic syndrome.

Question 42

What is the initial treatment of hypertensive encephalopathy?

Answer 42

Short acting hypertensives - in initial instance so that any potentially harmful drop in BP - which could lead to PRES (Posterior reversible encephalopathy syndrome) could be reversed.

Question 43

What is the subsequent treatment of hypertensive encephalopathy?

Answer 43

Long acting agents.
Sublingual nifedipine -precipitous drop in BP so its avoided or used with extreme caution

Question 44

Describe the process of treating hypertensive encephalopathy (a)

Answer 44

Use IV anti-hypertensive drugs
Bring BP down slowly (to avoid PERS) to a desirable level (stage 1) by 48 hours - though not to normal levels. 1/3rd of total BP reduction in 12 hours, next 1/3rd in subsequent 12 hours, final 1/3rd over 24 hours.

Or by 1/4 within 6 hours, and the rest in next 24 hours.

Question 45

Describe the process of treating hypertensive encephalopathy (b)

Answer 45

Common preferred drugs - Labetalol infusion, Na nitroprusside infusion, IV hydrallazine infusion.

After achieving the desired BP target, oral antihypertensives are then started.