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THE EGYPTIAN SOCIETY OF PEDIATRIC ALLERGY AND IMMUNOLOGY

 

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         These booklets are distributed (free of charge) during ESPAI's congresses and scientific meetings.

 

 

SYSTEMIC HYPERTENSION IN PEDIATRICS

 

How to measure the arterial blood pressure?

 

Infants

Older children

Auscultation

Auscultation

Flush method

 

Palpation method

 

Ultrasonic (Doppler) and oscillometric (Dinamp) devices

Blood pressure should be measured with a standard clinical sphygmomanometer, using the stethoscope placed over the brachial artery pulse, proximal and medial to the cubital fossa and approximately 2 cm above the cubital fossa. The appropriate cuff should have a bladder width that is approximately 40% of the child’s arm circumference when measured at a point midway between the acromion and the olecranon and it usually covers 80-100% of the arm circumference.

Blood pressure should be measured after 3-5 minutes of rest in the seated position with the cubital fossa at heart level. Infants and toddlers may be supine. The cuff should be inflated to a pressure of 20-30 mmHg above systolic blood pressure with a cuff deflation rate of 2-3 mmHg/sec. It should be recorded at least twice on each occasion.

Systolic blood pressure is determined by the onset of the ‘tapping’ Kortokoff sounds. The definition of the diastolic blood pressure is changed from muffling of the K sounds (the 4th Kortokoff sound) in children under 13 years old to the disappearance of the sounds (the 5th Kortokoff sound) in children of all ages.

When to diagnose systemic hypertension?

Hypertension is defined as an average systolic or diastolic blood pressure of greater than or equal to the 95th percentile for age, sex, weight and height of the patient measured at least on 3 separate occasions taken over weeks to months.

High normal blood pressure is defined as an average systolic or diastolic blood pressure of greater than or equal to the 90th percentile but less than the 95th percentile.

 

Blood pressure indicating hypertension

 

Age

Systolic (mmHg)

Diastolic (mmHg)

Newborn - 7 days

>100

-

8-30 days

>110

-

1 mo - 2 yrs

>124

>74

3-12 yrs

>130

>86

>12 yrs

>144

>90

 

Etiology of hypertension according to age

Newborns

Infants to 6 yrs

> 6 yrs

- Renal artery stenosis

- Renal artery thrombosis

- Broncho-pulmonary dysplasia

- Congenital renal anomalies

- Coarctation of the aorta

- Renal parenchymal disease (as acute GN and renal failure)

- Coarctation of the aorta

- Renal artery stenosis

- Essential hypertension

- Essential hypertension

- Renal parenchymal disease

- Medication (steroids)

- Renal artery stenosis

- Endocrine, metabolic (Cushing syndrome, hyperthyroidism, adrenal hyperplasia, pheochromocytoma)

- Neurologic (increased intracranial tension)

  

Evaluation of the child with hypertension:

 

1-        History:

Ask about

                 Family history of hypertension

                 Symptoms of nausea, headache, irritability, failure to thrive and deterioration of school performance, blurring of vision.

                 Heart disease

                 Symptoms indicating renal or metabolic abnormalities

                 Current medications (steroids)

                 Cerebral stroke (coma, convulsions)

                 Use of an umbilical catheter in the newborn

 

2-        Examination: (use appropriate-sized blood pressure cuff)

                 Blood pressure and pulses should be taken in all four extremities (differential pulses or differences in blood pressure between upper and lower extremities suggest coarctation of the aorta)

                 In the abdominal examination note the presence and size of both kidneys. An abdominal bruit suggests renal artery stenosis.

                 Note edema, thyroid size, hirsutism, striae and other signs of endocrine disorder.

                 Note signs of hypertensive encephalopathy such as seizures, stroke, altered mental status and focal neurological signs.

                 Perform a thorough fundoscopic examination looking for arteriovenous kinking, tortuosity, hemorrhage or papilledema.

 

 

Normal values of BP according to age

Age

Sex

Mean

90th%

95th%

1-3 d

1mo-2yr

2-5yr

6-7yr

8-9yr

10-11yr

12-13yr

14-15yr

 

16-18yr

 

 

 

 

 

 

 

Boys

Girls

Boys

Girls

65/41

95/58

101/57

104/55

106/58

108/60

112/62

116/66

112/68

121/70

110/68

75/49

106/68

112/66

114/73

118/76

120/77

124/78

132/80

126/80

136/82

125/81

78/52

110/71

115/68

117/78

120/82

124/82

128/83

138/86

130/83

140/86

127/84

 

 

3-        Assess the severity of hypertension:

Mild

Moderate

Severe

Asymptomatic and

Diastolic pressure > 90th percentile

Mild symptoms or

Diastolic pressure > 95th percentile

Signs of cong. HF or hypertensive encephalopathy or accelerated hypertension

 

4-        Performance of basic diagnostic evaluation:

Phase 1

Phase 2

Phase 3

  CBC

  Urine analysis

  Urine culture (if 2ry hypertension)

  BUN, creatinine, electrolytes, Ca, uric acid

  Lipid profile (if suspect 1ry hypertension)

  Renal sonar

  Echocardio-graphy

  Renal scan with ACE inhibitor

  Renin profiling

  Urine catecholamines

  Plasma and urinary steroids

   Renal artery imaging or renal vein sampling

   Metaiodobenzylguanidine (MIBG) scan of the adrenals

   Caval sampling for catechol-amines

 

5-        Plan of therapy:

 

A- Non-pharmacologic therapy (initial management):

                          Weight reduction for obese patients (may result in up to 5-10 mmHg reduction in systolic pressure and 5 mmHg reduction in diastolic pressure)

                          Decrease Na intake (lower pressure by about 5 mmHg) by decreasing salt intake in all types of food.

                          Change in the lifestyle and decrease the stress.

                          Discourage cigarette smoking and alcohol in the family.

                          Avoid (stimulant medications, sympathomimetics, amphetamines, steroids and decongestants)

B-       Pharmacologic therapy (for selected patients with essential hypertension and those with 2ry hypertension)

1-        Treatment of acute severe hypertension (hypertensive crisis) by I.V. drugs:

It is a serious condition which may lead to hypertensive encephalopathy or heart failure so urgent therapy is needed with the following rules:

                 Select an agent with a rapid and predictable onset of action.

                 It must be with minimal CNS side effects to avoid confusion between the disease symptoms and the drug side effects.

                 Stepwise reduction of BP is recommended to avoid inadequate organ perfusion. It should be reduced by 1/3 of the total planned reduction during the first 6 hours and the remaining amount over the following 48-72 hours. (Table 1)

                 After initial control of BP maintenance therapy can be made with oral drugs.

How to infuse Na nitroprusside?

The contents of the vial is dissolved in 2 ml glucose 5%, then the amount (50 mg) is added to 500 mL glucose 5%. The concentration in this solution is (100 mcg/mL). It is rapidly inactivated by light (photochemical degradation), so bottle and tubing system should be covered with aluminum paper.

The rate of infusion in mL/hour is calculated from the following formula:

Rate (mL/hour) = weight (Kg) dose (mcg/Kg/min) 60 (min/hour) / Conentration (mcg/mL)

2-     Treatment of chronic (non-emergency hypertension): (Table 2)

           The basic rule is to start therapy with ONE oral drug and the starting dose should be low, then it can be gradualy increased every 2-3 days, until the desired therapeutic response is reached.

           If BP remains uncontrolled and combined therapy is needed, the 2 drugs should belong to different groups (different mechanisms of action).

           How to select appropriate drugs to use?

In selecting a drug regimen for long-term use, an understanding of the underlying pathophysiology is helpful to choose the drug that alters the disease pathology as follows:

-         Young patients with essential hypertension who require drug therapy may be treated with the 1st line drugs initially with a diuretic or a beta-blocking agent or both. Both drug groups may be lipogenic and serum lipids must be followed.

-         Patients with volume-dependent hypertension usually respond adequately to diuretics.

-         Patients with high renin, high cardiac output failure respond best to beta-blockers and if BP is not lowered adequately a Ca-channel blocker may be added and an ACE inhibitor may replace the beta-blocker.

-         ACE-inhibitors are useful not only in patients with high renin hypertension that is secondary to renovascular or renal parenchymal disease but also in patients with high renin essential hypertension.

-         In most cases of neonatal hypertension high angiotensin production is the likely cause which follows partial occlusion of a renal vessel by a thrombus, captopril is an effective agent in most of them but used with careful attention to renal function.

-         In patients with neural crest tumours and high circulating levels of catecholamines, alpha-blocking agents are used and beta-blocking drugs are also needed to control the cardiac rate.

 

Table (1): Drugs used in hypertensive emergency

Drug

(duration in hrs)

Mechanism of action

Dosage

Available preparations

Side effects

Diazoxide

(6-24)

Arteriolar vasodilation

2-5 mg/Kg/ dose (max 100 mg) over half an hr, may be repeated after 3-6 hrs, IV or IM

Hyperstat vial 300 mg/20 mL (15 mg/mL) i.e. 1mL/3 Kg body weight

- Tachycardia

- Hypotension

- Hyperglycemia

- Na and H2O retention and edema in patients with myocardial dysfunction

- Nausea and vomiting

Hydralazine

(2-4)

Arteriolar vasodilation (improves renal and cerebral blood flow)

0.4-0.8 mg/Kg/dose every 6 hours

Apresoline amp (20 mg/ml)

Apresoline tab (25 mg)

- Tachycardia

- Headache, nausea, sweating, anorexia, flushing, lacrimation, conjunctivitis, tremors

- Drug-induced lupus

Methyldopa

(6-8)

Inhibition of central sympathetic flow

5-10 mg/Kg/ dose IV only repeated every 6-8 hrs

Aldomet amp (250mg/5ml)

Aldomet tab (250 mg)

- Sedation

- Psychic depression

- Hepatic dysfunction

Na nitroprusside

(With infusions)

Direct arteriolar and venous vasodilation

0.5-8 mcg/Kg/min IV infusion

Niprid vial (50 mg + 2 ml glucose 5%)

- Thiocyanate production

- Hypothyroidism

Frusemide

(4-6)

Diuresis (when other drugs are not available)

2 mg/Kg/ dose IV can be repeated after 4-6 hrs

Lasix amp.

- Hypokalemia

- Alkalosis

 

 

Table (2): Common drugs used in control of hypertension in pediatrics.

Drug

(duration in hrs)

Mechanism of action

Dosage

Available preparations

Side effects

I) Angiotensin converting enzyme inhibitors (ACE inhibitors)

Captopril

(6-8)

             ACE inhibitors by competitive inhibition hypertension)

      Arteriolar vasodilation

0.5-2 mg/Kg/ day

Capoten 25 and 50 mg tab

- Proteinuria

- Neutropenia

- Rash

- Fever

- Pruritis

- Hypotension

- Taste impairment

Enalapril
(24)

ACE inhibitor

5-10 mg/Kg/ dose

Enalapril, Renitec 5 and 20 mg tab

 

II) Adrenergic blockade

Propranolol

(6-8)

 

 

Blocking the beta adrenergic receptors

0.5-2 mg/Kg/ day

Inderal 10 and 40 mg tab

- Bradycardia

- Bronchospasm

Atenolol

(8-12)

Blocking the beta adrenergic receptors

50-100 mg/day

Tenormin 50 and 100 mg tab

- Bradycardia

- Bronchospasm

- Fatigue

- Sleep disturbance

Prazocine

(8-12)

          Alpha-receptor blockade

      Arteriolar and venous dilation

0.1-0.4 mg/Kg/day, initial dose one tab/day then increase gradually

Minipress 1 and 2 mg tab

First dose orthostatic hypotension

III) Diuretic agents

Hydrochloro-thiazide

(12-24)

Diuresis

0.5-2 mg/Kg /day

Hydrex

- Hypokalemia

- Hyperurecemia

- Hypercalcemia

Frusemide

(4-6)

Diuresis

0.5-2 mg/Kg/ day

Lasix 40 mg tab

- Hypokalemia

- Alkalosis

Spironolactone

(8-12)

Diuresis (K sparing)

1-3 mg/Kg/ dose

Aldactone 25 and 50 mg tab

- GIT upset

- Hyperkalemia

- Hyponatremia

- Osteomalacia

IV) Vasodilators

Hydralazine
(6-8)

Arteriolar vasodilation (the drug of choice in infant hypertension)

0.5-2 mg/Kg/ day max 200 mg/day

Apresoline 25 mg tab

Ser-Ap-Es tab /hydralazine 25 mg, reserpine 0.1 mg, hydrochlor-thiazide 15 mg

- Tachycardia

Minoxidil

(12-24)

Arteriolar dilation

0.2-1 mg/Kg/ day max 50 mg/day

 

- Hypertrichosis

- Fluid retention

V) Calcium Channel Blockers

Nifedipine

(8)

Ca channel blocker

0.2-2 mg/Kg/ dose max 10-20 mg

Epilat 10 mg cap, Epilat retard 20 mg tab

- Tachycardia

- Facial flushing

Amlodipine

(12)

Ca channel blocker

0.5 mg/Kg /day max

10 mg/day

Amlodipine

5 mg, 10 mg tab

 

VI) Sympatholytic agents

Alpha-methyldopa

(6-8)

CNS sympathetic antagonism

10-20 mg/Kg /day

Aldomet 250 and 500 mg tab

- Sedation

- Psychic depression

- Hepatic dysfunction

- Drug fever

Clonidine

(6-8)

Alpha-agonist in CNS

3-5 mg/Kg /dose

 

- Sedation

- Constipation

- Rebound withdrawal hypertension

 

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