PHEOCHROMOCYTOMA
Pheochromocytoma is a catecholamine secreting neoplasm associated with hyperfunction of the adrenal medulla. [It may appear wherever chromaffin cells are located.]
It can occur at any age, but is most common between the ages of 30 & 60, it is uncommon in people older than age 65. Most of them are benign, 10% are malignant with metastasis.
Etiology & Pathophysiology
Tumors located in the adrenal medulla produce both increase epinephrine and norepinephrine. [Those located outside the adrenal gland tend to produce epinephrine only. May occur as component of multiple endocrine neoplasia (MEN) II, an autosomal -dominant syndrome characterized by pheochromocytoma, thyroid carcinoma, hyperparathyroidism and Cushing's syndrome with excess ACTH.]
Clinical Manifestations
1. Excess secretion of norepinephrine and epinephrine produces hypertension, hypermetabolism and hyperglycaemia.
Hypertension may be paroxysmal (intermittent) or persistent (chronic).
a. Chronic form mimics essential hypertension; however antihypertensives are not effective.
b. Headaches and visual disturbances are common.
2. BP as high as 350/200 mm Hg has been recorded. Such BP elevations are dangerous and may precipitate (life-threatening complications, including) cardiac dysrhythmias, dissecting aneurysm, stroke and acute renal failure.
3. The hypermetabolic and hyperglycaemic effects produce excessive perspiration, tremor, pallor or face flushing nervousness, elevated blood glucose levels, polyuria, nausea, vomiting, diarrhoea, abdominal pain and paraesthesia [Hyperglycaemia may result from conversion of liver and muscle glycogen to glucose by epinephrine secretion, occasionally requiring insulin to maintain normal blood glucose levels]
4. Emotional changes, including psychotic behaviour, may occur
[Symptoms may be triggered by allergic reactions, physical exertion, emotional upset or may occur without identifiable stimulus.]
Diagnostic Evaluation
[Determination of the catecholamines in urine and blood offers the most direct and conclusive test for overactivity of the adrenal medulla.]
1. Determination of levels of vanillylmandelic acid (VMA), [an end product of catecholamine catabolism] metanephrine [(metabolites and epinephrine and norepinephrine)) are elevated in 24 hour urine sample.
(normal urinary values (VMA): 2-6 mg/24 hr). In addition, urine collected over a 2-3 hr. period after a spontaneous or induced attack of hypertension should be assayed for catecholamine content. Coffee, vanilla, chocolate, and certain fruits and vegetables and drugs are eliminated from the diet before assessment for VMA, since these substances may alter the test results.]
2. Epinephrine and norepinephrine in urine and blood are elevated while patient is symptomatic.
3. CT scan and MRI of the adrenal glands or of the entire abdomen are done to identify tumor
4. Clonidine suppression test is used to distinguish essential hypertension from pheochromocytoma.
Medical Management
1. Alpha adrenergie blocking agents phentolamine (Regitine) or smooth muscle relaxants (sodium nitroprusside [Nipride]) - quickly lowers the BP.
Long acting Alpha Blockers Phenoxyhenzamine (Dibenzyline) used after the Long acting a blockers patient's BP is stable to begin preparation of the patient for surgery. [Preliminary patient preparation includes effective control of BP and blood volumes. Usually this is carried out over 10 days to 2 weeks].
Phentolamine or phenoxybenzamine [may be used safely without causing undue hypotension] these inhibit the effects of catecholamines but do not alter their synthesis or degradation.
2. B adrenergic blocking agents may be used in patients with cardiac dysrhythmias or in those not responsive to a adrenergic blocking drugs. [a adrenergic and Beta adrenergic blocking agents must be used with caution, because patients with pheochromocytoma may have increased sensitivity to them.]
3. Catecholamine synthesis inhibitors alpha methyl pyrosine (metyrosine) used when the effects of catecholamines are not reduced by adrenergic blocking agents.
4. Unilateral or bilateral adrenalectomy or other tumor removal. [Surgical removal of the tumor, usually with adrenalectomy]
Nursing Interventions
1. Remain with patent during acute episode of hypertension.
2. Ensure bed rest and elevate the head of bed 45 during severe hypertension.
3. Carry out tasks and procedures in calm, unhurried manner with the patient.
4. Instruct patient about the use of relaxations exercises. Reduce environmental stressors by providing a calm, quiet environment. Restrict visitors.
5. Eliminate stimulants (coffee, tea, cola) from the diet.
6. Reduce events that precipitate episodes of severe hypertension palpation of the tumor, physical exertion, and emotional upset.
7. Administer sedatives as prescribed to promote relaxation and rest.
8. Monitor for orthostatic hypotension after administer of phentolamine (Regitine).
9. Encourage oral fluids and maintain IV infusion preoperatively to ensure adequate volume expansion going into surgery.
10. Monitor vital signs, ECG, arterial blood pressure, neurologic status and urine output closely postoperatively.
11. Assess for and report complications of hypertension, hypotension and hyperglycaemia.
12. Maintain adequate hydration with IV infusion to prevent hypotension (Because reduction of catecholamines immediately post-operatively causes vasodilation and enlargement of vascular space, hypotension may occur).
13. Monitor I/O and laboratory results for BUN, creatinine and glucose.
14. Instruct patient how and when to take medications.
[Warm patients who take metyrosine (Demser) of sedation and need to avoid taking other CNS depressants and participating in activities that require alertness; need to increase fluid intake to atleast 2,000 ml/day to prevent kidney stones.]
15. [Inform patient regarding the need for continued follow-up for:
a. Recurrent of pheochromocytoma
b. Assessment of any residual renal or cardiovascular injury related to preoperative Hypertension\
c. Documentation that catecholamines levels are normal 1-3 months post-operatively (by 24 hours urine test)
Complications
Metastasis of tumor.
