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An elevated blood pressure level in childhood can predict an increased cardiovascular risk in adult life. The increasing prevalence of childhood obesity necessitates regular surveillance of blood pressure to detect abnormal blood pressure and hence increased cardiovascular risk. Identifying hypertension in children allows for treatment, assessment of target organ damage and investigation of aetiology.
Measurement of Blood Pressure
The most common methods are:
(1) Aneroid sphygmomanometry (manual blood pressure)
(2) Oscillometry using automated devices such as DINAMAP (Critikon).
Mercury manometers are no longer in routine clinical use. Aneroid devices are not as accurate as mercury manometers and require regular calibration. Oscillometry detects arterial pulsations by transducer. The mean arterial pressure is measured, and systolic and diastolic recordings are calculated from a mathematical formula. There is good agreement between DINAMAP readings and blood pressures obtained by invasive central aortic measurements. DINAMAP values are generally 6-7 mm Hg higher for systolic and 2-4 mm Hg lower for diastolic. DINAMAP recordings have the potential for less variability, less error and greater reproducibility. DINAMAP measurements may be inaccurate in low birth weight or preterm infants where it may overestimate BP. Ambulatory blood pressure monitoring is also available for investigation of those with suspected hypertension, those at risk of developing hypertension or difficult to mange blood pressure.
Appropriate Cuff Size
This refers to the size of the inflatable bladder. The correct size is based on the diameter (thickness) of the arm, not the age of the child. Length is not as important. The widest cuff that can be applied to the arm should be used, with the bladder covering at least two thirds of the upper arm, and the length of the cuff should completely encircle the arm. Small cuffs result in a spuriously high BP, whereas the risk of a spuriously low blood pressure from too large a cuff is minimal. It is better to use a cuff which too large than one that is too small.
The cuff should be at heart level. Blood pressure should be measured on the arm only. There are no significant differences in BP between supine and erect as long as the cuff is at heart level and the child is volume replete.
The child should be seated in a quiet room for at least 5 minutes before taking the blood pressure. The right arm is preferred for consistency and because of the possibility of aortic coarctation (falsely low recording in the left arm.) Blood pressure should not be measured routinely on the leg as this may result in a false high reading.
Definition of Systolic and Diastolic BP
Systolic BP = 1st Korotkoff sound (K1). Diastolic BP = K5 in young children, K4 in adolescents. Use K4 (muffling of the sounds) in young children if K5 is very low, in which case record both.
Variables Affecting the Measurement of BP
Several variables can affect BP measurement including:
- Patient behaviour (anxiety, cooperation)
- Medications (beta-agonists, steroids)
- Observer variability (detection of Korotkoff sounds)
- Cuff size (as above).
There are significant variations in published normal measurements due to these differences.
Normal Blood Pressure
Current normative data is based on auscultation and there is no normative blood pressure data that is based on recordings measured from oscillometric devices.
There is limited data available on infants and young children. There is no significant difference between sexes in the first 5 years of life. Blood pressures rise gradually from 2 to 5 yrs of age, at a rate of approximately 1 mm Hg per year, and at a rate of 1.5 mm Hg per year from 7 to 11 years of age. In older children a wide variation of "normal values" are reported. Approximately 40% of the variability of BP in children is related to height, weight, triceps skin fold thickness, and arm circumference. The Fourth Report on the Diagnosis, Evaluation and Treatment of High Blood Pressure in Children and Adolescents presents new data and the reader is advised to consult this extensive report.
See BP tables below
When Should BP be Measured?
It should be an integral part of the physical examination. Measure it 4 to 5 times in early school age, after which only children with "high" BP (>75th centile) need following. Measure BP more often in "high risk" children: IDDM, obesity, hyper-lipoproteinemia (child or parent), periodically high BP, risk factors in a parent (severe hypertension, early stroke or MI), renal disease, syndromes known to be associated with hypertension.
Definition of Hypertension
A single moderately elevated measurement does not indicate hypertension. There must be repeated evaluation under basal conditions, over time. A very high blood pressure measurement requires urgent evaluation and treatment.
The 4th report definitions are as follows:
|Pre hypertension (previously borderline hypertension)||is defined as an average SBP and/or average DBP between 90th and 95th centile. This group is considered at increased risk for hypertension.|
|Hypertension||Average systolic and/or diastolic BP > 95th centile for age,
sex and height obtained on at least 3 occasions.
- Stage 1 hypertension average SBP ± DBP 95 to 99% for age and sex with no end organ damage.
- Stage 2 hypertension: average SBP ± DBP ³ 99% ± end organ damage.
A patient with BP levels >95th centile in a clinic setting, who is normotensive outside the clinic setting has "white coat" hypertension
If a statistical definition of hypertension is used, then potentially 5% of children have hypertension, a prevalence which is not supported in clinical studies where 1-2% of children have hypertension.
Signs and Symptoms of Hypertension
The signs and symptoms of hypertension vary enormously. The underlying disease causing hypertension may also have symptoms.
- Neonates: Respiratory distress, sweating, irritability, pallor/cyanosis, failure to thrive, sepsis-like picture, cardiac failure, apnoea, vomiting, seizures
- Older children: Fatigue, encephalopathy, headache, heart murmur, blurred vision, anorexia, nausea, epistaxis, weakness (facial palsy), weight loss / gain, polydipsia / polyuria, tiredness, enuresis, abdominal pain, haematuria, short stature. Acute hypertension in older children may be heralded by, Bell's palsy, headaches, seizures, sudden visual loss, epistaxis or abdominal pain.
Causes of Transient Hypertension
- Acute glomerulonephritis, Henoch-Schonlein nephritis, haemolytic uraemic syndrome, other causes of acute renal failure.
- Post urologic surgery or renal transplantation.
- Acute hypovolaemia (nephrotic relapse, burns, adrenal + GI saline depletion).
- Acute hypervolaemia (excessive administration of blood, saline or plasma).
- CNS disease (tumour, infection, seizures, injury).
- Guillain-Barre syndrome.
- Lead Poisoning.
- Medications (steroids, sympathomimetics, contraceptive pill).
Causes of Sustained Hypertension
- Coarctation of aorta.
- Renin-dependent hypertension:
- Renal parenchymal: coarse renal scarring (reflux nephropathy, obstructive uropathy, neuropathic bladder), glomerulonephritis, polycystic kidney disease, haemolytic uraemic syndrome.
- Renal tumour
- Catecholamine-excess hypertension (pheochromocytoma, neuroblastoma)
- Corticosteroid excess (Congenital adrenal hyperplasia, Cushing's or Conn's syndrome)
- Essential hypertension.
Investigation of the Hypertensive Child
The level and urgency of investigation depend on the rapidity of onset, severity, and age. The younger the child, and the more severe the hypertension, the more likely there is an underlying cause. Initial investigation is focussed on the kidneys, as 80% have a renal abnormality. You must also search for evidence of end organ damage.
In children and adolescents with moderate to severely elevated BMI, extensive investigations may not be necessary in the absence of kidney disease.
First line Investigations
- Medical history (symptoms of hypertension, medications, trauma, growth)
- Family history (renal or CVS disease, endocrine tumours, phakomatoses)
a) Mental state and coma score (Encephalopathy).
b) Optic Fundi (papillodema, haemorrhage, exudates).
c) Visual acuity and pupillary responses (Visual impairment).
d) Tone, power and reflexes (Hemiparesis, Bell's palsy).
e) Tachycardia, gallop rhythm, hepatomegaly, crackles(Congestive heart failure).
f) Abdominal masses or bruits (Renal enlargement ,R Art stenosis).
g) Signs of virilisation or cushingoid habitus (CAH, Cushing's syndrome).
h) Skin (neurofibromatosis)
- Urinalysis (urinary sediment, microscopy and culture)
- Cardiac investigations (CXR, ECG, echocardiogram)
- Renal function (U&E, creatinine, chloride, acid base, FBC, GFR estimation)
- Renal Ultrasound
Doppler study of renal arteries may be considered if there is significant suspicion of renovascular hypertension (e.g. very high BP in young children, elevated plasma renin, neuro-cutaneous syndromes). Doppler scans require specialist vascular sonographer skills and should only be requested after discussion with your local radiology department.
Second Line Investigations
- Further imaging of the urinary tract (DMSA scan, MCU)
- Imaging of renal vasculature (CT angiography or MR. Angiography)
- Urine catecholamines
- Plasma renin and aldosterone
- ESR and ANA
Other Investigations (on advice from renal team)
- Renal vein renin sampling, arteriography, isotope scan for pheochromocytoma
NOTE: A normal ECG does not exclude left ventricular hypertrophy
Hypertensive urgency is defined as a significant elevation of blood pressure without evidence of end organ injury. Patients are symptomatic with headaches or nausea but without end organ involvement. The patient is clinically stable.
Treatment with oral hypotensive agents is indicated if BP is above the 99th centile for age, height and gender, on three occasions 30 minutes apart. See BP tables below.
The choice of agents are:
- Beta blockers (labetolol, atentolol)
- Vasodilators (isradipine, felodipine, amlodipine, minoxidil)
- Angiotensin converting enzyme inhibitors (captopril, lisinopril, enalapril)
- Diuretic if volume overload is evident.
Sublingual nifedipine is unpredictable and should be avoided.
|Isradapine:||0.1 mg/kg/dose q 6- 8h.
Hospital only. Will need to be changed to a different medication if patient requires outpatient antihypertensive therapy.
NOT TO BE USED AS A MAINTENANCE MEDICATION
|Labetalol:||See dosing table|
|Enalapril:||See dosing table|
|Hydralazine:||0.15mg/kg iv q 3-4 hourly. Short acting rapid onset
Should not be used as maintenance medication.
This can be given on the ward.
Longer acting drugs such as amlodipine, lisinopril may be started but will not provide acute control of blood pressure
Defined as a severe elevation of blood pressure associated with a clinical picture of rapid and progressive central nervous system, visual, myocardial, haematological or renal deterioration. Fibrinoid necrosis of arterioles with retinal exudates and haemorrhages occur. Congestive heart failure may occur, with infants being particularly prone to this complication.
There is no specific level of BP that constitutes a hypertensive emergency. It is defined as a blood pressure high enough to cause acute injury to target organs
|Heart||left ventricular failure|
|Brain||hypertensive encephalopathy (9 - 33% of children)|
The most common causes in children are renal scarring from reflux nephropathy, and acute nephritis. Children are more prone to hypertensive encephalopathy than adults, and you must differentiate this from stroke or subarachnoid haemorrhage.
Management of the Hypertensive Emergency
- Admit the child to PICU
- Consult paediatric nephrologist and intensivist on call
Acute severe hypertension requires urgent treatment to prevent end organ damage. In chronic severe hypertension, slow smooth BP reduction is strongly recommended. It is often difficult to know whether hypertension is acute or chronic at the first presentation. Signs of end organ damage are more likely in chronic hypertension (eyes, heart, kidney), and less likely to be present in acute severe hypertension.
There is a high risk of neurological sequelae (spinal infarction, blindness) if anti-hypertensive drugs cause a precipitous fall in blood pressure.
- Sublingual nifedipine is unpredictable and should be avoided if the duration of hypertension is unclear and there are signs of end organ damage.
- Reduce blood pressure urgently.
- Secure IV access before commencing therapy
- Monitor BP and pupillary responses frequently during therapy
- Use continuous intra-arterial pressure monitoring. Dinamap is a second option in children aged over 5 years
- Aim to reduce blood pressure by one third of the total planned reduction in the first 24 hours, and the remaining 2/3 over the next 48 to 72 hours
- The choice of intravenous antihypertensive drug is at the discretion of the treating physician. These need to given in ICU.
- IV Labetalol: a bolus of 0.2 - 1 mg/kg, followed by a constant infusion (1 mg / ml in 0.9% NaCl). Begin infusion at 1 mg/kg/hour. Increase the infusion rate at 10 - 15 minute intervals until there is an effect. If there is no effect at a dose of 2.5 mg/kg/hour, choose another agent.
- IV Sodium nitroprusside infusion (0.5-10micrograms/kg/min) may be used as a second option. In this case, intra-arterial blood pressure monitoring is mandatory
- IV Hydralazine as above
- If BP falls too rapidly, give boluses of normal saline
- Avoid using ACE inhibitors until a renovascular cause has been excluded
Management of Primary Hypertension
- Weight reduction is the mainstay in obesity related hypertension.
- Dietary modification with emphasis on sodium intake reduction is strongly encouraged in those who have blood pressures in the prehypertensive range as well those with established hypertension.
- Lifestyle changes are integral to the successful treatment of hypertension.
- Pharmacological therapy is indicated when primary interventions are unsuccessful. Single agents which are suitable for daily dosing is preferred. Examples are ACE inhibitors, calcium channel blockers, b blockers.
- The goal for pharmacological therapy is reduction of blood pressure to <90% percentile.
Table of Blood Pressure Levels for Age & Height
Adapted from The Fourth Report on the Diagnosis, Evaluation and Treatment of High Blood Pressure in Children and Adolescents 2004.
The 90th percentile is 1.28 SD, the 95th percentile is 1.65 SD, and the 99th percentile is 2.33 SD above the mean.
Neonatal Blood Pressure Values
Estimated BP values after 2 weeks of age in infants from 26 to 44 weeks postconceptional age
Reproduced with permission from Joseph Flynn (Pediatr Nephrol (2000) 14:332-341).
Oral antihypertensive drugs for management of hypertension in children 1-17 years old
Goonasekera CDA, Dillon MJ. Measurement and interpretation of blood pressure. Arch Dis Child. 2000;82:261-265.
Fourth Report on the Diagnosis, Evaluation and Treatment of High Blood in Children and Adolescents Pediatrics. 2004;114:555-576.
de Man SA, André JL, Bachmann H, et al. Blood pressure in childhood: pooled findings of six European studies. Journal of Hypertension. 1991;9:109-114.
Flynn JT. Neonatal hypertension: diagnosis and treatment. Pediatr Nephrol (2000) 14:332-341.
Kemp A, McDowell JM, editors. Paediatric Pharmacopoeia. 13th edition. Melbourne: Pharmacy Dept Royal Children's Hospital; 2002
Guy's, St Thomas' and Lewisham Hospitals. Paediatric formulary. 5th Edition. London: Guy's and St Thomas' Hospitals Trust; 1999.
Mehta DK, Exec editor. BNF for children 2007. London: British Medical Association and the Royal Pharmaceutical Society of Great Britain; 2007
Strauser LM, Groshang T, Tobias JD. Initial experience with isradipine for treatment of hypertension in children. Southern Medical Journal 2000; 93(3): 289-93.
Takemoto C, Hodding J, Krauss D. Pediatric Dosage Handbook 15th Edition; Lexicomp 2008
The Fourth Report on the Diagnosis, Evaluation and Treatment of High Blood Pressure in Children and Adolescents, Pediatrics. 2004; 114: 555-576
Did you find this information helpful?
- Date last published: 11 June 2015
- Document type: Clinical Guideline
- Services responsible: Paediatric Nephrology
- Author(s): William Wong
- Editor: Greg Williams
- Review frequency: 2 years
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