Hypertension in the oncology patient

Shared care information

Hypertension can occur for a variety of reasons. Probably the commonest reason in children (particularly adolescents) is high dose steroid treatment. This often needs treatment but is rarely an emergency. Management of hypertension should be discussed with the paediatric oncologist and often the paediatric nephrologist as well. Drug doses as listed in the dosage table.

Background

Hypertension is a common sign in paediatric oncology patients.

Borderline hypertension can be managed in a "wait and watch" fashion, whereas marked hypertension ( > 99th centile) may need to be managed urgently in view of the risk of hypertensive encephalopathy. The risk of acute hypertensive complications is aggravated in patients who have other co-morbidities/organ dysfunction.

Causes of Hypertension

Hypertension is most often a result of:

• Wilms tumour compressing the normal kidney and inducing reno-vascular hypertension.

• Neuroblastoma - chronic hypertension is usually secondary to kidney compression as for Wilms tumours. Hypertensive crises may be induced by massive release of catecholamines, e.g., during surgery/biopsy of a neuroblastoma.

• Brain tumours and raised intracranial pressure.

• Therapy-induced - steroid, CSA, tumour lysis syndrome.

• Multifactorial eg stem cell transplant, steroids and cyclosporin.

Normal Ranges

Use the Blood Pressure Tables and judge a patient hypertensive if systolic and/or diastolic pressure > 95th%tile for age, sex and height. BP consistently above the assigned level should be treated. For full BP ranges and 95 centile levels in children, see:

• BP ranges in boys

• BP ranges in girls

Treatment of Hypertension

Choice of therapy depends on the severity of the hypertension and its underlying cause.

The paediatric nephrologist should be contacted for advice on a patient requiring treatment for hypertension; it is mandatory they are consulted urgently in the event of a hypertensive crisis.

The first step is to consider the underlying cause:

• If there is fluid overload, then decrease IVF therapy.

• For raised ICP, start mannitol and dexamethasone.

• If renal compression is the cause then anti-hypertensive therapy will be needed until tumour bulk can be reduced by medical or surgical means.

• If the cause is drug therapy then check for toxicity e.g., cyclosporin, or support with antihypertensives over the treatment course e.g., steroids.

Hypertensive urgency

Hypertensive urgency refers to a situation where there is elevated blood pressure, resulting in symptoms such as headache, chest pain, blurred vision, but without organ damage.

Measurement of blood pressure (BP):ensure appropriate cuff size, preferably applied on upper limb. Lower limb BPs are more variable, up to 20mmHg higher than upper limb BPs. Take into account pain and agitation. GVHD after HSCT is particularly associated with pain/discomfort

Children with moderate to severe hypertension should be discussed with the renal team. They can usually be managed effectively with the stepwise introduction of:

1. Oral labetolol (1-2 mg/kg BD initially which can increase to 10 mg/kg (max 600 mg) QID)

2. Oral isradipine 0.1 - 0.15mg/kg/dose prn 6 hourly.

   if BP not controlled add

3. Oral frusemide if salt and water retention is suspected.

Hypertensive Crisis/Acute Hypertensive Encephalopathy

This is: "A severe elevation of BP associated with a clinical picture of progressive and rapid CNS, visual, myocardial, haematological or renal deterioration."

This scenario is usually encountered when the BP is particularly high but can also be seen when the BP appears only moderately elevated and

• the patient is suffering from tumour lysis syndrome

  Under these circumstances, the aetiology is usually fluid overload due to continuing hyperhydration in the face of worsening renal function. Treatment should be discussed with the renal team and usually involves diuretics.

• post-stem cell transplant thrombotic thrombocytopenic purpura (TTP) syndrome develops.

  TTP is a microangiopathy with intravascular coagulation due to "endothelial inflammation" as a result of disordered immune mechanisms. Recognised early by raised reticulocytes, raised LDH and increased % fragmented RBCs. Patients then develop low Hb and refractory thrombocytopenia. Haematuria and proteinuria may develop if the kidneys are involved in the thrombotic microangiopathy.

Under both these circumstances, patients may rapidly develop posterior leucoencephalopathy syndrome.

Treatment of Hypertensive Crisis/Acute Hypertensive Encephalopathy

• Discuss with the paediatric nephrologist.

• Drugs with a rapid action are necessary but require a titrated continuous infusion and careful administration to prevent sudden hypotension resulting in end organ damage.

• Labetalol and sodium nitroprusside are both effective. Labetalol is easier to administer as Na+ nitroprusside needs to be administered in ICU.

• Avoid simultaneous administration of oral hypotensive agents or diuretics in the initial management of hypertensive crisis; these are best reserved until the blood pressure is safely controlled.

• Do not aim for a normal blood pressure but rather to lower to safe levels (e.g., in adults a diastolic of 100mmHg is the aim). The target BP must be clearly defined at the start of treatment. (See BP for girls , and BP for boys.)

• An IV line must be available throughout so that saline or plasma can be administered if the BP drops unexpectedly. A central line is also valuable to monitor the CVP for detection of volume overload or depletion, however, the usual oncology lines are generally not suitable for this purpose.

• In the event of a convulsion, diazepam and a loading dose of phenytoin should be administered intravenously in addition to steps being taken to reduce blood pressure by IV Labetalol.

Posterior Reversible Encephalopathy Syndrome

The features of this syndrome may develop as part of a hypertensive crisis and are characterised by sudden onset of:

• seizures

• reduced level of consciousness

• cortical blindness

• MRI changes particularly affecting the occipital lobes.

Symptoms and signs often reverse as rapidly as they appear. With prompt control of blood pressure, withdrawal of agents which precipitated the hypertension and correction of hypomagnesaemia.

Hypertension in Neuroblastoma Patients

In preparation for surgery, hypertension should be treated with labetolol. However, chronic hypertension is probably due to renal compression rather than catecholamine excess and may require treatment with an ACE-inhibitor. See the drug dose table below.

Drug Dose Table

Click on link to view Drug Dose table. Includes information on Labetalol infusion.