Pediatric Hypertension Flashcards
What is blood pressure?
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.
How is the Direct Intra-arterial measurement of BP carried out?
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.
How is the auscultatory method for measuring BP carried out?
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.
How is the palpation method (flush technique) for measuring BP carried out?
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.
How is the oscillometric method for measuring BO carried out?
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.
How does the Doppler Ultrasound technique for measuring BP work?
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.
How does the Doppler Ultrasound technique for measuring BP work?
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.
How does the Doppler Ultrasound technique for measuring BP work?
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.
How are ambulatory BP measurements carried out?
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.)
What is the definition of HTN in adults?
It is an epidemiological definition based on the risk of adverse events (e.g. stroke) - >140/90 mmHg.
What is the definition of HTN in adults?
It is an epidemiological definition based on the risk of adverse events (e.g. stroke) - >140/90 mmHg.
What is the definition of HTN in adults?
It is an epidemiological definition based on the risk of adverse events (e.g. stroke) - >140/90 mmHg.
What is the definition of HTN in adults?
It is an epidemiological definition based on the risk of adverse events (e.g. stroke) - >140/90 mmHg.
What is the definition of HTN in adults?
It is an epidemiological definition based on the risk of adverse events (e.g. stroke) - >140/90 mmHg.
What is the definition of HTN in children?
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,
What are the other definitions for HTN in children?
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
How is the BP centile plotted?
The height centile is determined first. If it falls between 2 centiles, the closest one is used, otherwise the lower height centile is used.
What is hypertensive emergency?
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.
What is Hypertensive Urgency?
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.
What are the 7 rules of correct BP measurements according to Antwi?
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.
What are three things you must know in the technique of bp measurements
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.
In which conditions (11) should you suspect hypertension in a child?
*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.
How would you describe the aetiology of childhood hypertension?
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.
What are the broad causes of childhood hypertension?
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
