Sipple syndrome

The article "Surgical treatment of pheochromocytomas" is the basis for this AORN Journal independent study. The behavioral objectives and examination for this program were prepared by Janet S. West, RN, BSN, CNOR, clinical editor, with consultation from Patricia A. O'Neill, RN, MS, professional, education specialist, Center for Perioperative Education.

A minimum score of 70% on the multiple-choice examination is necessary to earn four contact hours for this independent study. Participants receive feedback on incorrect answers. Each applicant who successfully completes this study will receive a certificate of completion. The deadline for submitting this study is July 31, 1998.

Send the completed application form, multiple-choice examination, learner evaluation, and appropriate fee to

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c/o Home Study Program

2170 S Parker Rd, Suite 300

Denver, CO 80231-5711

BEHAVIORAL OBJECTIVES

After reading and studying the article on surgical treatment of pheochromocytomas, the nurse will be able to (1) discuss major components of pheochromocytomas (ie, embryology, incidence, pathophysiology, clinical manifestations), (2) describe criteria (ie, biochemical tests; suppressive, provocative diagnostic tests; localization studies) used to diagnose patients with pheochromocytomas, (3) discuss perioperative nursing care for patients undergoing surgical treatment of pheochromocytomas, and (4) describe the perioperative nurses' roles when caring for patients undergoing surgical treatment of pheochromocytomas.

The term pheochromocytoma comes from the Greek words phaios, which means dusky; chromo, which means color; and cytoma, which means tumor. Pheochromocytomas are tumors that produce excessive amounts of catecholamines (eg, norepinephrine, epinephrine). These tumors also have abnormal growths of cells that stain darkly with chrome salts.[1] Pheochromocytomas develop from chromaffin tissue of the sympathoadrenal system. They not only produce catecholamines but also may secrete polypeptides and amines.[2]

EMBRYOLOGY

Embryonically, chromaffin cells originate from the neural crest that extends longitudinally along the neural tube of the embryo. Approximately six weeks after conception, neural crest-derived chromaffin cells give rise to various structures in the embryonic sympathetic nervous system, autonomic ganglia, inner medulla region of the adrenal gland, and the ventral surface of the aorta (ie, paraganglia cells).

The term paraganglia refers to scattered groups of extraadrenal chromaffin cells that are similar to the chromaffin cells found in the adrenal medulla.[3] These cells develop from tissue remnants of the adrenal medulla during its embryologic migration from the neural crest[4] and can be found anywhere in the body from the pelvic floor to the base of the skull. Paraganglia cells are found along the paraaortic sympathetic chain, in the organs of Zuckerkandl located at the aortic bifurcation, in the walls of the urinary bladder and mediastinum, and at the carotid bifurcations (Figure 1).[5]

Pheochromocytomas can cause one of the most dramatic, life-threatening crises in the human body.[6] The excessive production of catecholamines often results in explosive paroxysms (ie, sudden reappearance or increases in the intensity of symptoms), including wide blood pressure (BP) fluctuations, arrhythmias, panic attacks, and alterations in glucose metabolism. Irreversible cardiovascular disease and end-organ damage from hypertension frequently result in death if pheochromocytomas are not removed surgically.

INCIDENCE, ETIOLOGY

Pheochromocytomas occur in approximately 1.9% of the general population, and men and women appear to be affected equally.[7] Less than 50% of patients are diagnosed with pheochromocytomas while alive. For example, in a study of 54 patients diagnosed at autopsy, only 13 patients (24%) were diagnosed while they were alive.[8]

Approximately 90% of all pheochromocytomas are benign (ie, innocuous) and are found in the adrenal medulla. The "rule of 10" provides a handy mnemonic to describe the location and incidence of pheochromocytomas: 10% are extraadrenal, 10% are multiple or bilateral, 10% recur after surgical resection, 10% are malignant (ie, cancerous, fatal), 10% occur in children, and 10% are familial.[9]

Familial pheochromocytomas most often occur as part of the syndrome called multiple endocrine neoplasia (MEN). The MEN type IA syndrome includes not only pheochromocytomas but thyroid carcinomas and hyperparathyroidism. The MEN type IIB syndrome (ie, Sipple's syndrome) includes not only pheochromocytomas but thyroid carcinomas and mucosal neuromas and conditions such as thickened corneal nerves, intestinal ganglioneuromatosis, neurofibromatosis, and von Hipple-Lindau disease.[10] The MEN type IIB syndrome is transmitted as an autosomal dominant trait; therefore, it is important to screen family members of patients suspected of familial pheochromocytomas.

CATECHOLAMINES

Catecholamines originate from the amino acid tyrosine. When chromaffin cells absorb tyrosine from the blood, tyrosine undergoes sequential changes that are dependent on specific enzymes. Tyrosine is converted first to L-dopa (ie, the chemical precursor to dopamine), which is converted to dopamine, and dopamine is converted to norepinephrine. In the central and peripheral adrenergic systems, norepinephrine is the final product. In the adrenal medulla, however, norepinephrine is converted to epinephrine under the influence of cortisol, which drains from the adrenal cortex.[11]

Epinephrine is the predominant hormone of the adrenal medulla. It is stored in chromaffin granules until it is needed by the body. Secretion occurs when nerve fibers release acetylcholine, which permits calcium to enter the chromaffin cells. These cells then marginate (ie, form a margin) and fuse with the plasma membrane, releasing catecholamines in the blood stream.[12] The plasma half-life of catecholamines is approximately one to two minutes.

When dopamine, epinephrine, and norepinephrine are secreted into the blood stream, they may be absorbed by platelets by way of a neuronal pump, converted to sulfates or metanephrines (ie, inactive metabolites of epinephrine), or escape further metabolism. Metanephrines can be transformed by monoamine oxidase (MAO) into intermediates that are metabolized into vanillylmandelic acid (VMA).

Dopamine may remain unaltered or be converted to sulfates or homovanillic acid (HVA). Figure 2 depicts catecholamine synthesis and metabolism. The overall result of these metabolic processes is the excretion of several inactive compounds and unaltered forms of dopamine, norepinephrine, and epinephrine in the urine. Consequently, 24-hour urine output analyses for these substances have a high diagnostic value.

In patients who undergo pheochromocytoma-related catecholamine synthesis, storage and metabolism of catecholamines is abnormal. Norepinephrine and epinephrine usually are secreted in large amounts, and dopamine secretion is decreased. Exceptions do occur, however, and sometimes epinephrine secretion is high, and norepinephrine and dopamine secretions are decreased.[13] In addition, substances such as vasoactive intestinal peptides (VIPs), enkephalins, adrenocorticotrophin hormone (ACTH), endogenous opiates, somatostatin, calcitonin, and serotonin can be found in pheochromocytomas.[14]

The different clinical manifestations that result from the above substances may complicate diagnoses of pheochromocytomas. For example, VIPs are potent vasodilators, so the cardinal indicator of pheochromocytomas (ie, hypertension) may be minimal or absent.[15] Tumors that cosecrete ACTH may cause signs and symptoms of Cushing's syndrome. In pheochromocytoma-related MEN syndromes, hypertension is not a prominent feature, but hypercalcemia may occur, which suggests that these tumors produce a parathormone-like substance. Table 1 addresses the effects of these cosecretory products.

[TABULAR DATA NOT REPRODUCIBLE IN ASCII]

Malignant pheochromocytomas have the highest levels of dopamine, although norepinephrine levels also may be very high. Researchers believe that the enzymes necessary for the conversion of dopamine to norepinephrine and norepinephrine to epinephrine are deficient in malignant tumors. Clinical manifestations, therefore, can vary considerably in patients depending on the type of tumor present.[16]

Catecholamines exert their effects on body systems by binding to particular membrane receptors classified as alpha ([Alpha])- and ([Beta])-adrenergic receptors. These receptors are subdivided further into [Alpha.sub.1], [Alpha.sub.2], [Beta.sub.1] and [Beta.sub.2] receptors. After catecholamines bind to plasma membrane receptors, second messenger substances are induced into the cells, which cause other intracellular changes to occur. Catecholamines may be agonistic (ie, stimulatory) or antagonistic (ie, inhibitory) in nature.[17] For example, they have an agonistic effect on [Alpha]-adrenergic receptors but have an antagonistic effect on [Beta]-adrenergic receptors. The two main exceptions to this norm occur in the intestines where catecholamines act on [Alpha]-adrenergic receptors to produce relaxation and in the myocardium where they act on [Beta]-adrenergic receptors to excite myocardial tissue.[18]

Norepinephrine is an [Alpha]-adrenergic agonist, which causes vasoconstriction, hypertension, and reflex bradycardia.[19] Marked perspiration, impaired gastrointestinal motility, dilated pupils, decreased insulin secretion, and increased glycogenolysis also result from its agonistic action.

Epinephrine is a [Beta]-adrenergic agonist that acts on [Beta.sub.1] receptors to increase heart rate, myocardial contraction, and oxygen consumption. Low levels of epinephrine act on [Beta.sub.2] receptors to vasodilate skeletal blood vessels. Epinephrine's cardiovascular effects include diastolic hypotension, systolic hypertension, tachycardia, and increased cardiac output.[20] High levels of epinephrine affect [Alpha]-adrenergic receptors, which results in vasoconstriction. Stimulation of [Beta.sub.2] receptors promotes glycogenolysis; mobilizes fatty acids from adipose tissues; increases the basal metabolic rate, weight loss, and heat intolerance; and causes relaxation of smooth muscles in the bronchi, intestines, and uterus.[21]

Small amounts of dopamine stimulate [Alpha]-adrenergic, [Beta]-adrenergic, and dopamine receptors, which results in increased systolic blood pressure and cardiac output. It also causes dilation of the renal, cerebral, and coronary blood vessels. At higher levels, dopamine causes positive inotropic (ie, increased force of muscle contractions), chronotropic (ie, rhythmic movements such as increased cardiac rate), and dromotropic (ie, increased speed and conduction of nerve fibers) reactions.[22]

CLINICAL MANIFESTATIONS

Pheochromocytomas can have diverse clinical manifestations, but in general, they reflect the secretory agents involved. For example, [Alpha]-adrenergic stimulation occurs most often in patients because norepinephrine-secreting tumors predominate.[23] Conversely, [Beta]-adrenergic stimulation occurs less often because epinephrine-secreting tumors are less common. Tumors that secrete dopamine may not have cardiovascular manifestations; however, tumors that contain enkephalins, VIPs, and ACTH may reflect the secretion of these hormones. Perioperative nurses should remember that pheochromocytomas mimic many disorders and that many times pheochromocytomas may not be evident at first.

Patients in their fifth decade of life most often develop paroxysmal symptoms of pheochromocytomas. These symptoms are described by "the five Ps:"

* pressure (ie, a sudden, major increase in BP),

* pain (ie, an abrupt onset of a throbbing headache; chest, abdominal pain),

* perspiration (ie, profuse, generalized diaphoresis),

* palpitations, and

* pallor (Figure 3).

Hyperglycemia, visual disturbances, tremors, fever, and orthostatic hypotension also may occur. These paroxysmal symptoms may be spontaneous or precipitated by postural changes, anxiety, exercise, micturition, bladder distention, and other factors that increase intra-abdominal pressure (eg, tumor palpation, Valsalva maneuvers).[24]

Hypertension. Hypertension is the cardinal symptom most often seen in patients with pheochromocytomas. It may be persistent or paroxysmal with intervening normotensive and hypotensive periods, depending on whether hormones are released continuously or in episodic spurts. Severe paroxysmal symptoms of peripheral vasoconstriction may result in false low BP measurements, unobtainable pulses, and obvious acral (ie, relating to the extremities) gangrene.[25] Sustained diastolic hypertension is considered a clinical hallmark of pheochromocytomas.

Hypotension. Hypotensive periods, which may be postural in nature, also are attributed to low blood volume because of persistent peripheral vasoconstriction, secretion of vasodilators, the down-regulation of receptor sites, and impaired sympathetic reflexes caused by chronic exposure to catecholamines.[26] Patients with norepinephrine-secreting tumors usually are hypertensive and have a reflex bradycardia sometimes as low as 15 beats per minute.[27] Patients with epinephrine-secreting tumors may present with hypotension and rapid heart palpitations.[28] Although hypotension is rare, epinephrine-secreting tumors can cause extensive peripheral vasodilation and hemodynamic collapse.[29]

Other symptoms. Hypermetabolism, weight loss, heat intolerance, and hyperglycemia caused by inhibition of insulin secretion also may occur.[30] Myocarditis may occur in some patients and is believed to result from excessive excitation-contraction coupling with coagulation necrosis. Cardiomyopathy is reversible if catecholamine stimulation is eliminated. Stroke and hypertensive encephalopathy with altered mental status, focal neurologic signs, and papilledema also may occur.[31]

Some patients may present with acute abdomens from hemorrhage and tumor necrosis. Others may present with histories of heart palpitations, hematuria, micturition syncope, and headaches. They also may develop lactic acidosis without shock caused by epinephrine increasing lactate production and metabolic activity. Norepinephrine decreases tissue perfusion and oxygenation, resulting in anaerobic metabolism and further lactate production.[32]

DIAGNOSIS

Early diagnoses of pheochromocytomas are critical because medication therapy and surgical removal of these tumors can cure patients before cardiovascular disease and end-organ damage occur from hypertension. When diagnosing pheochromocytomas, health care providers should be aware of the many pheochromocytoma look-alike conditions that exist (Table 2). Criteria used to diagnose pheochromocytomas include clinical suspicion, biochemical tests, and localization studies.[33]

Clinical suspicion. Patients who present with unexplained or paroxysmal episodes of increased BP, pain, perspiration, palpitations, and pallor should raise health care providers' suspicions of the presence of pheochromocytomas. Also, patients who have a family history of MEN syndrome should be suspected of having pheochromocytomas.

Biochemical tests. Laboratory tests that reflect catecholamine metabolism can confirm the presence of pheochromocytomas. Patients' dopamine, norepinephrine, epinephrine, metanephrine, and VMA levels are measured through 24-hour urine output analyses.[34] Physicians also may request random urine specimens after patients' hypertensive episodes because briefly elevated catecholamine levels may be missed in 24-hour urine output analyses. Table 3 shows the normal laboratory values for catecholamines and metabolites.

Approximately 90% to 95% of all patients diagnosed with pheochromocytomas have elevated VMA and metanephrine levels, and 98% of these patients have altered catecholamine levels.[35] Twenty-four hour urine outputs are collected in sealed leak-proof containers that contain strong acid preservatives.[36] Normal urine creatinine levels confirm that 24-hour urine collections are complete. If patients experience paroxysmal hypertension, 24-hour urine collections should begin at the onset of these episodes. Normal metanephrine levels in 24-hour urine collections indicate that patients do not have chromaffin tumors.(37)

If the results of 24-hour urine output analyses are uncertain, laboratory technicians examine patients' total and fractionated levels of plasma catecholamines (ie, epinephrine, norepinephrine, dopamine). Many factors (eg, postural change, exercise, emotional arousal, time of day [eg, sleep results in lower amounts of catecholamine]) can alter plasma catecholamine levels. Phlebotomists draw blood specimens for plasma catecholamines under controlled conditions to avoid stress-related catecholamine increases in patients.

Patients undergo overnight fasts and are placed in supine resting positions at least 30 minutes before laboratory blood samples are taken. Nurses insert indwelling IV catheters with heparin locks at least 20 minutes before blood specimens are drawn. Phlebotomists draw the blood samples into chilled, evacuated, heparinized glass laboratory tubes. Laboratory technicians separate patients' plasma in refrigerated centrifuges and store the plasma specimens at -70[degrees] C (-94[degrees] F) until the time the assay is performed.(38) Diagnostic indicators of pheochromocytomas include metanephrine levels greater than 3 mg in 24 hours or total catecholamine levels greater than 2,000 pg/mL of plasma.(39) Significant elevations in urine epinephrine or metanephrine levels suggest adrenal medulla tumors, whereas elevations in urine norepinephrine levels suggest extraadrenal tumors.

Before patients' catecholamine and metabolite levels can be tested, they must restrict their consumption of foods that contain tyramine (eg, aged cheese, red wine, pickled herring, yogurt, liver, caffeine, vanilla extract) and must avoid certain medications (eg, MAO inhibitors, antihypertensives) to prevent false-positive laboratory results. Patients must not take MAO inhibitors because they increase epinephrine levels by blocking intraneural metabolism. Anti-hypertensive medications (eg, vasodilators, [Beta]-blockers, diuretics) may increase catecholamine secretion, whereas other antihypertensive medications (eg, methyldopa, clonidine hydrochloride) may decrease catecholamine secretion.(40) Perioperative nurses should remember that some medications initially promote the release of stored catecholamines before they exert their hypotensive side effects.(41) Table 4 lists medications that may increase or decrease levels of catecholamine and metabolites in laboratory tests.

Table 4

MEDICATIONS THAT ALTER CATECHOLAMINE

AND METABOLITE LABORATORY VALUES(1)

(*) Clonidine hydrochloride only decreases catecholamine and metabolite levels in patients with normal adrenal glands or essential hypertension.

NOTE

(1.) W F Young, "Pheochromocytoma: A brief management guide," Hospital Medicine 29 (October 1993) 67-79.

Other abnormal laboratory test findings that may occur in patients with pheochromocytomas include elevations in hemoglobin and hematocrit levels, which are caused by decreased plasma volume secondary to catecholamine vasoconstriction. Patients rarely present with erythropoetin-secreting tumors, which produce absolute increases in hemoglobin and hematocrit levels, but patients may have decreased erythropoetin stimulation that results in anemia. Hyperglycemia caused by catecholamine stimulation of glycogenolysis, gluconeogenesis, insulin inhibition, and glucagon production often is seen. Metabolic acidosis also may occur from anaerobic conditions produced by [alpha]-mediated vasoconstriction and glycolysis through the Emden-Meyerhof pathway and its resultant lactic acid production.(42)

Suppressive, provocative diagnostic tests. Suppressive and provocative tests can be dangerous and must be performed with great care. Phentolamine mesylate, an [alpha]-adrenergic blocking medication, commonly is used as a suppressive agent. A positive response to this medication occurs within two to three minutes after administration and is evident by decreases in patients' systolic BPs of 35 mm Hg and diastolic BPs of 25 mm Hg. An initial dose of 1 mg phentolamine mesylate should be given, and if no response occurs, a 5-mg dose is administered. Nurses need to monitor patients' BPs carefully and have certain medications (ie, norepinephrine injection, nitroprusside sodium, propranolol hydrochloride) on hand to reverse any drastic changes in patients' systolic and diastolic BPs.(43) Norepinephrine injection stimulates [alpha] and [Beta]-adrenergic receptors; nitroprusside sodium relaxes both arteriolar and venous smooth muscle; and propranolol hydrochloride reduces cardiac oxygen demand by blocking catecholamine-induced increases in heart rate, BP, and the force of myocardial contractions.

Clonidine hydrochloride suppression tests are performed on patients with pheochromocytomas to rule out neurogenic hypertension. Patient testing involves orally administering 300 mg of clonidine hydrochloride and drawing blood samples at 30-minute intervals for two hours. This medication reduces sympathetic nervous system activity by central [alpha][sub.2]] agonism and thereby decreases plasma catecholamine levels. Pheochromocytomas are not innervated (ie, they secrete autonomously); therefore, if tumors are present, patients' plasma catecholamine levels will not be decreased by the administration of clonidine hydrochloride.(44)

Provocative diagnostic tests are conducted with histamine, tyramine, or glucagon if patients are normotensive at test time; however, these diagnostic tests carry the risk of dangerous increases in patients' BPs and often yield false-negative test results. Glucagon most often is used for provocative testing because it does not affect normal adrenal gland function. Patients with pheochromocytomas, however, experience hypertensive crises in response to glucagon and develop more than two-fold increases in their plasma catecholamine levels. To prevent hypertension, [alpha]-blocking medications (eg, phentolamine mesylate, pheoxybenzamine hydrochloride) are administered to patients suspected of having pheochromocytomas before glucagon is administered for provocative testing.(45)

Tumor localization studies. Tumor localization studies consist of computed tomography (CT), magnetic resonance imaging (MRI), and radioiodine-labeled m-iodobenzylguanidine (MIBG) scans. The radiologic imaging procedures of choice are CT and MRI scans because they provide excellent sensitivity for adrenal tumors (ie, 94 accuracy) and good sensitivity for extraadrenal tumors (ie, 84% accuracy). These scans are the most accurate and minimally invasive means of localizing pheochromocytomas. In addition, they afford clear views of the anatomic relationships between tumors and surrounding tissues.

If both CT and MRI scans are negative in the presence of patients' clinical manifestations of pheochromocytomas, MIBG scans are performed. These scans employ a radiopharmaceutical agent (ie, iodine-131[[sup.131.I]]) that has a molecular structure similar to norepinephrine. Radioactive [sup.131.I] isotopes localize in adrenergic tissues and provide excellent sensitivity for adrenal and extraadrenal tumors (ie, 86% to 94%). To prevent thyroid uptake of [sup.131.I] and subsequent hypothyroidism, patients are treated with a strong iodine solution (ie, Lugol's solution) or a saturated solution of potassium iodine before MIBG scans are conducted. Radioactive [sup.131.I] isotopes are excreted through patients' urine and may mask intravesical (ie, bladder) tumors. To prevent this problem, nurses insert Foley catheters into patients' bladders and monitor their urine outputs during MIBG scanning procedures.

Several medications adversely affect the results of MIBG scans. For example, reserpine depletes catecholamine stores, pseudoephedrine hydrochloride acts as a catecholamine agonist, labetalol hydrochloride and metoprolol tartrate block [Beta]-adrenergic responses, and tricyclic antidepressants block reuptake of epinephrine and increase its action.(46) In addition, these scans are expensive and have limited availability.

Patient management. Surgical resection is the treatment of choice for patients diagnosed with pheochromocytomas. The overall mortality rate is 1% to 3% in patients who are diagnosed and treated before surgery, compared to a 10% mortality rate in untreated patients who undergo surgical procedures for pathology other than pheochromocytomas.(47)

PREOPERATIVE PATIENT CARE

Preoperative care of patients who are scheduled to undergo surgical resections of pheochromocytomas requires good communication and coordination of patient care activities by all hospital team members. Preoperative care activities include the administration of phenoxybenzamine hydrochloride and other medications and specific nursing care measures to ensure optimal patient outcomes.

Phenoxybenzamine hydrochloride. Before patients undergo surgical resections of pheochromocytomas, they are given phenoxybenzamine hydrochloride to reverse the acute and chronic effects of excess catecholamines. Preoperative patient preparations usually begin approximately 10 days before scheduled surgical procedures. Phenoxybenzamine hydrochloride is both an [alpha].[sub.1]] - and an [alpha].[sub.2]]-adrenergic blocking agent. The [alpha].[sub.1]]-blockade effects of this medication include reduced vasoconstriction and decreased systolic and diastolic BPs (ie, the desired effect). The [alpha].[sub.1]]-blockade effects activate baroreceptors in the great vessels and carotid sinus, which results in reflex tachycardia. The reflex tachycardia is potentiated by the release of norepinephrine that results from the [alpha].[sub.2]]-blockade effects of phenoxybenzamine hydrochloride.

Side effects of phenoxybenzamine hydrochloride include postural hypotension, miosis (ie, pupil constriction), nasal congestion, inhibition of ejaculation, diarrhea, and fatigue. Cautious dosage begins with 10 mg of oral phenoxybenzamine hydrochloride twice a day with an increase of 10 to 20 mg every two days until patients can tolerate daily dosages of 40 to 100 mg of oral phenoxybenzamine hydrochloride. Patients also must demonstrate normotension or only moderate postural hypotension and have no paroxysmal symptoms. Surgeons may withhold phenoxybenzamine hydrochloride from patients 48 to 72 hours before surgery to prevent postoperative hypotension, or they may continue the medication until the day before surgery to prevent possible intraoperative hypertensive episodes.

Other medications. Alternative preoperative medications include [alpha].[sub.1]]-adrenergic blocking agents (eg, prazosin hydrochloride, terazosin hydrochloride). These medications have fewer side effects than phenoxybenzamine hydrochloride and are preferred for long-term therapy in patients with malignant pheochromocytomas and metastases. Patients who have tachycardia greater than 120 beats per minute, arrhythmias, or tumors that primarily secrete epinephrine also require [Beta]-adrenergic blocking agents. Beta-adrenergic blocking agents must not be administered before [alpha]-adrenergic blocking agents are given to patients because they will inhibit [Beta]-receptor-induced vasodilation and cause severe vasoconstriction that may result in hypertensive crises.(48)

Propranolol hydrochloride is a [Beta]-adrenergic blocking agent that is used if patients do not have a history of bronchospasms. Patients who have bronchospastic disease can be given metoprolol tartrate, which primarily acts on the heart's [Beta].[sub.1]]-adrenergic receptors and spares the bronchial [Beta].[sub.2]]-adrenergic receptors.(49) Metyrosine, which inhibits tyrosine conversion to catecholamines, also may be given preoperatively. It frequently is used in patients with unresectable tumors and catecholamine-induced cardiomyopathy. Calcium channel blockers (eg, nifedipine, verapamil) that inhibit calcium-mediated catecholamine secretion from tumors, also may be administered to preoperative patients. Calcium channel blockers are believed to prevent myocarditis and coronary artery spasms.(50) Depending on institutional procedures, patients may be placed in a special care unit for close observation and continuous monitoring by nurses a few days before surgery.

Preoperative nursing care measures. Liberal salt diets often are prescribed for patients to offset their contracted blood volumes -- a result of prolonged vasoconstriction. Nurses administer 1 to 2 L of IV fluids to patients daily to ensure adequate hydration before surgery. They also draw blood samples for blood-type and cross-match screens because the vascularity of pheochromocytomas may cause intraoperative hemorrhage. Preoperative nurses monitor patients for hypertension or postural hypotension, by measuring patients' BPs consistently in the same arm and with patients in both lying and standing positions. They also record patients' daily weights at the same time of day to detect possible dehydration or edema.

Preoperative nurses instruct patients not to smoke tobacco or drink caffeine beverages because tobacco and caffeine can produce sympathomimetic effects and increase patients' BPs. Patients are given diets that are rich in calories, vitamins, and minerals. To prevent the release of catecholamines from pheochromocytomas, nurses instruct patients to

* guard against rapid position changes or straining,

* avoid wearing tight constricting clothing at their waistlines and over abdominal areas, and

* abstain from performing Valsalva maneuvers.

As patients often experience severe headaches, preoperative nurses should provide calm, restful environments (eg, darkened rooms, minimal interruptions) to facilitate relaxation. Providing these patients opportunities to listen to music of their choice also can be helpful. Decreasing emotional tension is a primary preoperative nursing intervention. Patients often experience increased anxiety in anticipation of events that may be painful or lead to undesirable outcomes. Open communication between health care providers and patients and family members is essential in all phases of perioperative patient care.

Nurses should explain every step of preoperative diagnostic tests (eg, blood, urine laboratory tests; localization studies), the essentials of surgical procedures (eg, Foley catheter insertions; location, size of surgical incisions), and postoperative patient expectations (eg, pain control, coughing, deep breathing, ambulation). Anesthesia care providers and perioperative nurses visit patients the day before surgery to offer reassurance, answer questions, and conduct any necessary preoperative assessments. Surgeons detail the risks, complications, and benefits of surgical procedures before patients sign surgical consents forms.

If patients are children, preoperative nurses interview children in conjunction with parents. They address children's preoperative, intraoperative, and postoperative phases of care within a developmental framework and take into account children's cognitive and psychosocial abilities. Nurses use medical play items, audiovisual aids, and puppets to facilitate learning. They explain the roles of staff members at children's level of understanding and arrange visits to the surgical suite in advance of the actual procedure. Pediatric patients normally have higher metabolic rates and different physiologic needs than adult patients. Preoperative nurses, therefore, must have a good understanding of normal physiologic and psychological parameters for pediatric patients of all ages.(51)

It is important to premedicate patients appropriately to reduce stress. Preoperative medication regimens vary from one institution to another. Preoperative medications, such as IV diazepam, meperidine hydrochloride, and scopolamine hydrochloride, are used extensively because they do not interact with catecholamines. Appropriate doses of IV midazolam hydrochloride and fentanyl citrate also may be administered. The use of IV morphine sulfate is not recommended because it may cause histamine production and the release of catecholamines. The administration of atropine sulfate may induce vagolytic or catecholamine-induced tachycardia.(52) To decrease the risk of nausea and vomiting, nonparticulate antacids (eg, 0.3 g sodium citrate), hydrogen blockers (eg, ranitidine hydrochloride), and gastrokinetic agents (eg, metoclopramide hydrochloride) may be given to improve gastric emptying.(53)

INTRAOPERATIVE PATIENT CARE

A well-integrated team approach by experienced surgeons, anesthesia care providers, and perioperative nurses is essential for successful patient outcomes. Perioperative nurses collaborate with surgeons and anesthesia care providers to plan specific care for patients undergoing surgical resection for pheochromocytomas. Nurses ensure that hallways in the surgical suite are quiet, and they eliminate unnecessary sound from overhead speakers or other loud noise disturbances. Perioperative nurses may arrange for patients to bypass the preoperative holding area to decrease their anxiety levels. If this is not possible, they should give patients headphones and a choice of taped music to listen to while they are in the preoperative holding area.

General anesthesia. The risk of hypertensive crises in patients is reduced with appropRiate induction of general anesthesia (eg, thiopental sodium commonly is used). Anesthesia care providers often use fentanyl citrate to avoid triggering the release of histamine and etomidate because it causes minimal cardiovascular disturbance and does not promote the release of catecholamines. Isoflurane and enflurane are the anesthetic inhalation agents of choice because they can be titrated to control BP. During the induction period, anesthesia care providers take strenuous measures to protect patients against hypoxia because oxygen deficits sensitize patients' myocardium to catecholamine-induced arrhythmias. Anesthesia care providers most often use vecuronium bromide, a nondepolarizing muscle relaxant, to achieve muscle relaxation. Vecuronium bromide does not have the undesirable side effects of suxamethonium chloride (ie, cholinergic agonism), tubocurarine chloride (ie, histamine release), or pancuronium bromide (ie, indirect sympathomimetic action).

OR preparation. The circulating nurse and scrub person prepare the surgical setups before the patient is transferred to the OR. The circulating nurse conducts a safety check of all electrical equipment (eg, electrosurgical unit, temperature regulating blanket's power console) to verify that it is in working order. The circulating nurse ensures that all necessary supplies for arterial, central venous, and other hemodynamic access lines are available to the anesthesia care provider. He or she also ensures that adequate supplies of IV volume expanders (eg, albumin, hetastarch) and blood products (eg, units of typed and cross-matched blood, platelets) are available. The circulating nurse makes arrangements for the patient's radiographic films and CT or MRI scans to be in the OR for placement on the lighted viewing board. He or she also ensures that cardiopulmonary resuscitation equipment is readily available.

Patient admission, induction. The circulating nurse checks the patient's hospital identification band, signed surgical consent form, the most recent laboratory test results, vital signs, and NPO and allergy statuses. He or she helps the anesthesia care provider attach the electrocardiogram (ECG) leads, BP cuff, pulse oximetry probe, and nerve stimulator to the patient. The anesthesia care provider inserts a peripheral IV line into the patient's forearm and induces general anesthesia. The anesthesia care provider performs a rapid-sequence intubation and uses a topical anesthetic to blunt any adrenergic responses to the intubation procedure. Adrenergic responses also can be expected during die skin incision, abdominal exploration, and surgical manipulation of the pheochromocytoma.(54)

Other patient preparations. After the patient is anesthetized, the circulating nurse inserts a Foley catheter, connects the catheter to a metered collection bag, and places the urine collection bag where the anesthesia care provider can monitor the patient's urine output. The anesthesia care provider inserts a radial arterial line (A-line) and a pulmonary artery catheter for hemodynamic monitoring of the patient. Arterial blood pressure monitoring is essential because high levels of catecholamines can cause peripheral pulses to disappear and make auditory monitoring impossible. The A-line also allows the anesthesia care provider to draw frequent blood samples for arterial blood gas (ABG) analysis. The anesthesia care provider inserts another wide-bore peripheral IV catheter into the patient's forarm to use if rapid fluid replacement is necessary.

Surgical approaches. The patient is positioned according to the surgical approach preferred by the surgeon. Traditional surgical approaches include transabdominal or lateral incisions, and modern-day approaches include laparoscopic incisions for the surgical removal of pheochromocytomas.

Lateral approach. If the surgeon can identify the pheochromocytoma clearly and the tumor is unilateral, the patient most often is placed in a lateral position for the surgical approach. This approach requires a nephrectomy instrument setup, which includes rib resection and vascular instruments, vessel loops, stainless steel surgical clips, and clip appliers.(55)

Surgical team members position the patient in a lateral position with the affected side uppermost. Team members position the OR bed to bend at the patient's twelfth rib. The circulating nurse places a pillow between the patient's legs, slightly flexes the lower leg, and keeps the upper leg straight. He or she applies wide-adhesive straps over the patient's hips to secure the patient to the OR bed. After the patient is positioned, the circulating nurse pads all the patient's bony prominences and performs the skin prep with an antimicrobial agent suggested by the surgeon and appropriate for the patient's allergy status. The scrub person gowns and gloves the surgeon and other surgical team members and places surgical drapes on the patient.

The surgeon performs the skin incision along the patient's twelfth rib from the posterior midline to the anterior axillary line. He or she uses an electrosurgical hand piece to divide the latissimus dorsi muscle and to expose the twelfth rib, which subsequently is excised. The surgeon incises the renal fascia and spreads the perinephric fatty tissue to expose the adrenal gland. The gland can be identified readily because it is more orange in color than the surrounding fat. The surgeon secures the arterioles with stainless steel surgical clips and gently dissects the adrenal gland. He or she ties the central vein with 2-0 silk sutures and transects the vein.

The anesthesia care provider flattens the OR bed so that the surgeon can reapproximate the renal fascia, intercostal muscles, and the latissimus dorsi muscle with 2-0 absorbable sutures. Hypotension often occurs at this time but responds to rapid IV fluid administration or [Alpha]-adrenergic stimulation. Advantages to the lateral approach for surgical resection of a pheochromocytoma include

* a shorter postoperative recovery period,

* increased respiratory comfort after surgery, and

* decreased incidence of paralytic ileus.(56)

Transabdominal approach. If the surgeon prefers the transabdominal approach for surgical resection of a pheochromocytoma, the scrub person opens a laparotomy tray that includes vascular instruments (eg, extra-long dissecting scissors; assorted sizes of tissue forceps, needle holders) and obtains assorted sizes of Penrose drains, stainless steel surgical clips, and clip appliers.(57) Surgical team members place the patient in a supine position, and the circulating nurse secures the patient's arms and thighs with safety straps.

The surgeon usually performs a bilateral subcostal incision because it allows him or her to examine the contralateral adrenal gland, paraspinal area, organ of Zuckerkandl, and bladder. Sometimes it is necessary to extend the surgical incision into the patient's thorax, which necessitates the insertion of chest tubes. To expose the patient's left adrenal gland, the surgeon reflects the left colon inferiorly, divides the splenocolic ligament, and reflects the pancreas and spleen medially. To expose the patient's right adrenal gland, the surgeon mobilizes the hepatic flexure of the colon inferiorly, reflects the duodenum medially, and retracts the right kidney inferiorly. He or she manipulates the adrenal gland as little as possible to prevent the release of catecholamines. The surgeon uses stainless steel surgical clips to control bleeding from the arteries and veins. He or she takes great care to secure die right adrenal vein because it is very short and empties directly into the vena cava.(58) After the surgeon excises the pheochromocytoma, the circulating nurse sends the specimen to pathology for histologic examination.

Possible complications. Ligation of the adrenal vein may cause the patient's BP to drop precipitously. If hypotension occurs during surgical resection, prompt IV fluid replacement is required to counteract the

* loss of vascular tone from removal of the patient's major source of catecholamines (ie, adrenal vein),

* down regulation of catecholamine receptors,

* preoperative [Alpha]-adrenergic blockade,

* patient's impaired cardiac response from [Beta]-adrenergic blockade, and

* patient's already constricted vascular volume. Surgical team members also should also be aware that pheochromocytomas are highly vascular and that intraoperative hemorrhage is a distinct possibility.

As a hypertensive crisis may occur from tumor manipulation and stored catecholamine release, the circulating nurse should ensure that the anesthesia care provider has a wide array of medications (eg, phentolamine mesylate, nitroprusside sodium, esmolol hydrochloride, lidocaine hydrochloride, norepinephrine injection) available to address whatever intraoperative complication may arise.

Other circulating nurse duties. The circulating nurse helps the anesthesia care provider monitor the patient's blood loss and renal perfusion status through serial urine measurements. He or she also assists with the collection of serial blood specimens for ABG analyses, hematocrit and glucose levels, an acid-base balance measurements. If the surgical procedure is a bilateral adrenalectomy, the circulating nurse helps the anesthesia care provider administer stress doses of IV glucocorticoids to the patient.

The circulating nurse or other designated member of the perioperative nursing team provides in-person intraoperative progress reports to the patient's family members to reduce their anxiety. Before the surgical procedure is finished, the circulating nurse completes all necessary intraoperative documentation; ensures that the needle, sponge, and instrument counts are correct; and informs the postanesthesia care unit (PACU) nurses of the patient's special needs. He or she ensures that the patient's bed is ready (ie, clean linen, oxygen tank, portable hemodynamic monitor attached at foot of bed) before the patient is transferred from the OR bed to the hospital bed. The circulating nurse checks the electrosurgical unit (ESU) dispersive pad site for redness or swelling and examines the patient's skin integrity for any changes. Surgical team members transfer the patient as a single unit from the OR bed to the hospital bed, and the circulating nurse and anesthesia care provider secure all IV tubing and catheters before the patient is transported to the PACU.

POSTOPERATIVE PATIENT CARE

The circulating nurse gives the PACU nurses a detailed report on the patient's status, which includes any changes in the patient's skin integrity, type and length of the surgical procedure, baseline hemodynamic readings, estimated blood loss, total volume of crystalloid and colloid IV fluids and blood products administered, and presence of any drainage devices. The PACU nurses monitor the patient's

* vital signs and hemodynamic status,

* fluid and electrolyte status,

* urine output,

* laboratory coagulation profiles, and

* carbon dioxide ([CO.sub.2]) elimination status for laparoscopic surgical procedures. The PACU nurses also compare the patient's laboratory results with the preoperative baseline readings.

The PACU nurses promptly administer IV analgesics to the patient for pain control. Medications are given through the patient's IV line in the PACU because intramuscular absorption is slow. The anesthesia care provider may order continuous epidural analgesia or a patient-controlled analgesia (PCA) pump. The PACU nurses endeavor to decrease the incidence of patient nausea and vomiting by avoiding rapid patient movements, preventing patient aspiration of saliva and gastric contents, and promptly administering antiemetics to the patient. The patient is discharged from the PACU after the anesthesia care provider performs an evaluation and the patient has a postanesthesia room (PAR) score of nine or 10. A PACU nurses gives a report to the surgical intensive care unit (SICU) nurses and two nurses transfer the patient to the SICU.

Surgical intensive care unit. The SICU nurses implement standard postoperative care for the patient (eg, encouragement of coughing, deep breathing, hydration maintenance, early ambulation). They also continue to monitor the patient for

* pain,

* fever,

* nausea and vomiting,

* an adequate airway,

* possible bleeding,

* hypertension and hypotension,

* hypoglycemia, and

* fluctuations in hemodynamic status.

If a bilateral adrenalectomy was performed or if there is an indication of hypoadrenalism, the SICU nurses continue to administer postoperative stress doses of IV glucocorticoids for two days. After two days, the surgeon decreases the patient's dosage to maintenance levels. By the second postoperative week, the patient takes oral fludrocortisone acetate twice a week to replace the mineralocorticoids. In general, the SICU nurses should expect the patient's plasma catecholamines to remain low after surgery due to partial or total removal of the adrenal gland and also because catecholamines have a short half-life of only a few minutes. After a bilateral adrenalectomy, glucocorticoid and mineralocorticoid therapy is required for life. Medication dosages are based on the patient's BP and if postural hypotension and edema are present. If the patient undergoes a unilateral adrenalectomy, glucocorticoid therapy continues for a varying period of time until the remaining gland can compensate for the body's needs.

Hypotension, hypertension. The patient may remain hypotensive for a few days after surgery, but volume replacement with IV fluids usually corrects this problem. Postoperative hypertension also may continue for a few days from the persistence of catecholamines within adrenergic neurons. The patient's BP normalizes, however, as catecholamine stores are depleted. Postoperative nurses should be aware that persistent hypertension could be a sign of residual or metastatic pheochromocytoma.

Hypoglycemia. The patient may experience hypoglycemia that is caused by excess insulin release that is no longer suppressed by catecholamines, and decreased lipolysis, glycogenolysis, and gluconeogenesis. Postoperative nurses should consider the possibility of hypoglycemia if the patient is slow to emerge from anesthesia or if lethargy or somnolence persists. Close monitoring of blood glucose levels and treatment with IV glucose solutions usually correct the patient's hypoglycemia.

Long-term care. The patient undergoes regularly scheduled laboratory tests to measure postoperative catecholamine levels and to rule out

* tumor development in retained adrenal or extra-adrenal tissue,

* tumor implantation occurrence, and

* evidence of metastatic disease.(59) The patient is asked to submit a 24-hour urine collection two weeks after surgery to check for catecholamines and their metabolites. Follow-up urine collections are obtained at one month, two months, six months, and then once a year after surgery.(60) The physician also checks the patient's BP and blood glucose levels at these visits.

Most malignant tumors are slow growing and often do not cause severe hypertension. If hypertension is a problem, patients are managed with phenoxybenzamine hydrochloride, propranolol hydrochloride, or labetalol hydrochloride.(61) Some patients may be managed with [Alpha]-methyltyrosine, which prevents conversion of tyrosine to catecholamines. This permits lower doses of [Alpha]-adrenergic blocking agents and reduces the side effects of induced [Alpha]-blockades.

Malignant tumors may spread locally or metastasize to bones, lungs, and soft tissue. The combination of certain chemotherapy agents (ie, cyclophosphamide, vincristine sulfate, dacarbazine) has proven helpful for some patients with malignant tumors. Some side effects from these chemotherapy agents include bone marrow depression and hypotension. Whether the tumor is malignant or benign, life-long follow-up visits are mandatory, as recurrences have been reported as long as 41 years after surgical resections.(62) Some metastatic tumors are so slow growing that patients can live 20 years or longer after their first surgical resections of pheochromocytomas.(63)

CASE STUDY

Mr D was a 50-year-old man who visited a nursing care center for his annual checkup. He informed the nurse practitioner that until recently he had been in good health and did not have a family history of high blood pressure, heart disease, or diabetes. Mr D explained to the nurse that approximately two weeks before this visit, he began to experience episodic headaches, a pounding heart, profuse sweating, and panic attacks. These episodes sometimes were precipitated by heavy exertion (eg, lifting, bending). Mr D mentioned, as an aside, that he also had developed cold feet, which required him to wear socks to bed except on hot summer nights.

Mr D's physical examination revealed the following vital signs: BP = 196/115, pulse = 60 beats/min, temperature = 37.0 [degrees] C (98.6 [degrees] F). His skin was pale and moist without neurofibromatosis or cafe-au-lait spots, and his urine was 2+ for glucose. Mr D weighed 100 kg (220 lb), and he was a nonsmoker. The nurse practitioner referred Mr D to a physician who saw him that afternoon.

The physician ordered the following laboratory tests: a complete blood count, liver enzyme studies, serum chemistries, a fasting serum glucose level, and a 24-hour urine collection for VMA analysis. Mr D's test results were normal, except for his serum glucose, which was 130 mg/dL (normal = 70 to 115 mg/dL) and his urine VMA, which was 40 mg/24 hr (normal = 2 to 7 mg/24 hr). The physician then ordered biochemical tests to measure Mr D's plasma catecholamines; and norepinephrine, epinephrine, and dopamine levels. The test results showed a total catecholamine concentration of 5,490 pg/mL (normal [is less than] 500 pg/mL), a norepinephrine level of 5,390 pg/mL (normal = 65 to 400 pg/mL), an epinephrine level of 15 pg/mL (normal = 15 to 55 pg/mL), and a dopamine level of 85 pg/mL (normal [is less than] 100 pg/mL).

A CT scan revealed a 6 x 3 cm tumor on Mr D's right adrenal gland. A subsequent MIBG scan revealed a similar finding but no evidence of an extra-adrenal tumor. Mr D's physician ordered serum parathormone, calcitonin, and thyroid function tests to rule out MEN syndrome and began Mr D on a daily regimen of 10 mg of oral phenoxybenzamine hydrochloride and 250 mg of oral metyrosine. He increased Mr D's phenoxybenzamine hydrochloride dosage 10 mg every other day and his metyrosine dosage every day until Mr D could tolerate a total daily dose of 50 mg of phenoxybenzamine hydrochloride and 2 g of metyrosine. The physician told Mr D that surgery for removal of the tumor was necessary and referred him to a surgeon.

The surgeon discussed the advantages and disadvantages of each surgical approach (ie, lateral, transabdominal, laparoscopic) in such a way that enhanced Mr D's understanding. The surgeon explained that a laparoscopic approach appeared to be appropriate because Mr D's CT and MIBG scans indicated a solitary tumor. He described the possible postoperative complications of a laparoscopic approach, which included the potential for

* [CO.sub.2] embolism;

* bowel, blood vessel, bladder, nerve perforations;

* surgical wound infections at the trocar sites;

* neck, back, and shoulder pain from retention of [CO.sub.2]; and

* abdominal bruising from grasping the skin during insertion of the Verres needle used to create the pneumoperitoneum.

The surgeon also explained that an open abdominal procedure was possible, if any intraoperative complications (eg, bleeding) developed. Mr D decided on the laparoscopic approach and signed the surgical consent form. Mr D reported to the nursing care center every other day to allow the nurse practitioner to monitor his BP. The nurse practitioner informed Mr D of the adverse effects of his medications and provided literature to reinforce her patient teaching. She stressed the importance of adhering to the following instructions.

* Drink at least 2 L of fluids every day to prevent renal crystal formations from metyrosine.

* Change positions slowly to prevent postural hypotension.

* Report any swelling of the lower extremities. Mr D's BP steadily decreased and by the day of the scheduled surgical procedure, his BP was 136/80. By this time, Mr D was taking 50 mg of phenoxybenzamine hydrochloride and 2 g of metyrosine daily.

Mr D was admitted to the hospital the day before surgery and underwent routine laboratory tests, a chest x-ray, and a 12-lead ECG. His vital signs remained normal during this time. A perioperative nurse and an anesthesia care provider visited Mr D the evening before his scheduled surgery, answered questions, and provided Mr D and his family members reassurance. The morning of surgery, perioperative team members transported Mr D to the preoperative holding area.

The preoperative nurse administered a prophylactic antibiotic (ie, 1 g cefazolin sodium) as ordered by the anesthesia care provider. The circulating nurse checked Mr D's NPO and allergy statuses and laboratory test results and placed his chest x-rays and CT and MIBG scans on the OR viewing board. She checked Mr D's skin integrity, which included the planned surgical incision and ESU dispersive pad placement sites. Before the circulating nurse brought Mr D into the OR, she placed the laparoscopic cart at the foot of the OR bed. The cart contained a Verres needle, a laparoscope, laparoscopic instruments (eg, an ESU device; scissors; graspers; stainless steel surgical clips; clip appliers; dissectors; 5-mm, 10-mm, 12-mm trocars), a [CO.sub.2] insufflator and tank, a camera and light source, two television monitors, a videocassette recorder, and a printer. She also positioned a suction device at the foot of the OR bed and ensured that a major abdominal setup was available.

Other members of the surgical team included a first assistant (ie, a surgical resident), camera operator, and scrub person. The circulating nurse oriented Mr D to the surgical suite and provided him reassurance. The anesthesia care provider and circulating nurse placed ECG leads, a BP cuff, and a pulse oximeter probe on Mr D. The anesthesia care provider prepared the capnography and oscillometric arterial BP monitors. He used 16-gauge angiocatheters to insert two peripheral IV lines in Mr D's forearms and inserted a radial A-line to measure his BP and to draw blood specimens for ABG analyses and plasma epinephrine and norepinephrine levels. The anesthesia care provider administered midazolam hydrochloride and fentanyl citrate to sedate Mr D before he inserted the IV lines.

The anesthesia care provider used 12 mg of midazolam hydrochloride, 750 mg of fentanyl citrate, 0.2% to 1.5% isoflurane, and 10 mg of vecuronium bromide to induce general anesthesia and fentanyl citrate and isoflurane to maintain the general anesthesia. After Mr D was intubated, the anesthesia care provider inserted a pulmonary artery catheter through Mr D's right jugular vein. The circulating nurse inserted a Foley catheter into Mr D's bladder to allow the anesthesia care provider to monitor Mr D's kidney perfusion and urine concentrations of epinephrine and norepinephrine.

Surgical team members placed Mr D in a supine position, and the circulating nurse secured Mr D to the OR bed with safety straps placed over his knees and chest. After the circulating nurse performed the skin prep with a povidone-iodine solution, the surgeon inserted a Verres needle through the periumbilical incision. He aspirated the attached syringe to ensure that the needle had not entered a blood vessel or the bowel. The surgeon introduced 5 mL of normal saline into Mr D's peritoneum by gravity. After the surgeon confirmed the position of the needle, he established a pneumoperitoneum with [CO.sub.2]. The surgeon directed the circulating nurse to begin [CO.sub.2] insufflation at a low-flow rate that was increased gradually to 9 L/min to prevent abdominal trauma. The circulating nurse closely monitored Mr D's intraabdominal pressure, which remained at 14 mm Hg throughout the procedure.

Surgical team members then turned Mr D to a full left lateral position. The circulating nurse placed a firm pillow under Mr D's left flank to extend the surgical site on his right flank. The surgeon inserted four 10-mm trocars 2 cm below the costal margin at the midclavicular, anterior, middle, and posterior axillary lines, respectively. The surgeon, first assistant, and camera operator inserted a laparoscope with attached camera, an irrigation/suction device, a laparoscopic electrosurgical hand piece, and other laparoscopic instruments into Mr D's abdominal cavity. The circulating nurse placed two television monitors on opposite sides of the head of the OR bed to afford the surgeon, first assistant, camera operator, scrub person, and circulating nurse clear views of the surgical site.

The surgeon used the Kocher maneuver to mobilize the hepatic flexure of the colon and free the second part of the duodenum by dividing its lateral avascular reflection. He incised the posterior liver attachments and retracted the right lobe upward. This exposed the underlying vena cava and the pheochromocytoma on Mr D's right adrenal gland. The surgeon dissected the leaves of peritoneum and Gerota's fascia from the tumor and divided the fascial attachments with the laparoscopic electrosurgical hand piece. The first assistant retracted the vena cava to expose the adrenal vein, which the surgeon secured with stainless steel surgical clips and clip appliers. The surgeon used small surgical clips and the electrosurgical hand piece for hemostasis of small blood vessels. He used a plastic specimen retrieval bag to remove the pheochromocytoma. The circulating nurse sent the specimen to pathology for histologic examination, which revealed a benign tumor.

While the anesthesia care provider closely monitored Mr D's hemodynamic parameters, he documented three intraoperative events that resulted in the release of catecholamines and caused hypertensive episodes:

* insertion of the endotracheal tube,

* induction of the pneumoperitoneum, and

* surgical manipulation of the right adrenal gland. The anesthesia care provider quickly adjusted Mr D's IV esmolol hydrochloride and nitroprusside sodium infusions to keep the BP between 120 and 150 mm Hg until the surgeon could ligate the right adrenal vein. After the right adrenal vein was ligated, the anesthesia care provider administered an IV infusion of 1,000 mL of hetastarch and 500 mL of lactated Ringer's solution. No significant intraoperative bleeding occurred, and Mr D's serum blood glucose level remained within normal limits.

The surgeon examined the surgical site for hemostasis and evacuated the [CO.sub.2] from Mr D's peritoneal cavity. He removed the trocars, inspected the insertion sites, and closed the surgical wound with absorbable, subcuticular sutures. He then injected the surgical sites with a local anesthetic to decrease Mr D's postoperative incisional pain. The scrub person applied self-adhesive wound approximating strips to each wound site. The anesthesia care provider reversed the neuromuscular blockade with IV neostigmine bromide and glycopyrrolate. After Mr D was extubated, the circulating nurse completed a final skin assessment and together with the surgeon and anesthesia care provider, transferred him to the PACU. The circulating nurse gave a complete report to the PACU nurses. Mr D's PAR score was nine upon his admission to the PACU.

Mr D remained hemodynamically stable in the PACU but complained of shoulder, neck, and back pain, which were attributed to retention of [CO.sub.2]. The PACU nurses administered prescribed meperidine hydrochloride through the PCA pump, which Mr D was taught to use. After two hours, the nurses transferred Mr D to the SICU and gave a complete report to the SICU nurses to provide continuity of care. Mr D remained in the SICU overnight and was transferred to the postsurgical unit where he remained hemodynamically stable. An IV infusion of 5% dextrose solution was administered at a slow rate for the next 24 hours. Mr D ambulated and ate a regular diet on the first postoperative day. He continued to experience shoulder pain, which he rated as a 3 on a 1-to-10 pain scale. Mr D's PCA pump was discontinued after 12 hours, and he was given acetaminophen with codeine #3 every four hours for pain for two days. On the third postoperative day, a 24-hour urine collection analysis showed normal levels of catecholamines and metanephrine.

The postsurgical nurses provided Mr D and his family members in-depth teaching regarding the importance of follow-up care for die rest of his life. Mr D was discharged on postoperative day four with instructions to return in two weeks for BP measurements and urine catecholamine testing. On Mr D's first postoperative visit, his vital signs were normal and a 24-hour urine sample contained normal quantities of catecholamines and metanephrines. His blood glucose levels also were normal, and his incision sites were intact and healing. Mr D completed a satisfaction survey and rated his care as excellent. He complimented the nurse practitioner at the nursing care center for her astute assessment and timely referral.

SUMMARY

Pheochromocytomas are tumors that develop from chromaffin tissue. Seventy percent of pheochromocytomas have diameters of 5 cm and weigh less than 70 g; however, they may be microscopic or weigh up to 4,000 g.(64) Pheochromocytomas most often are encapsulated and very vascular. Clinical manifestations vary with the type of pheochromocytoma diagnosed; however, complications such as hypertension, diabetes, and cardiac disease may prove fatal to patients. Pheochromocytomas that occur in children and pregnant women result in high morbidity and mortality rates for these patients.

A detailed family history is mandatory to rule out MEN syndrome, and if the family history is suggestive, follow-up of at least first-degree relatives should be undertaken. In most instances, surgical resections of pheochromocytomas is curative; however, surgery must occur before cardiovascular disease and endorgan damage develop from hypertension. Surgical procedures are very demanding on patients and require excellent preoperative, intraoperative, and postoperative nursing management. Long-term, follow-up care is necessary for detection of possible malignancies or recurring pheochromocytomas.

NOTES

(1.) C L Thomas, ed, Taber's Cyclopedic Medical Dictionary, 17th ed (Philadelphia: F A Davis, Co, 1993) 1494.

(2.) N L Benowitz, "Pheochromocytoma," Advances in Internal Medicine 35 (January 1990) 195-219.

(3.) K L Moore, T V N Persaud, The Developing Human: Clinically Oriented Embryology, fifth ed (Philadelphia: W B Saunders Co, 1993) 416.

(4.) J M Feldman, "Diagnosis and management of pheochromocytoma," Hospital Practice 24 (January 15, 1989) 175-179, 182, 187-189.

(5.) R Agana-Defensor, M Proch, "Pheochromocytoma: A clinical review," AACN Clinical Issues. Critical Care Nursing 3 (May 1992) 309-318.

(6.) E L Bravo, R W Gifford, Jr, "Pheochromocytoma," Endocrinology and Metabolism Clinics of North America 22 (June 1993) 329-341.

(7.) S S Werbel, K P Ober, "Pheochromocytoma: Update on diagnosis, localization, and management," Medical Clinics of North America 79 (January 1995) 131-153.

(8.) Feldman, "Diagnosis and management of pheochromocytoma," 175.

(9.) W F Young, Jr, "Pheochromocytoma: A brief management guide," Hospital Medicine 29 (October 1993) 67, 69.

(10.) Ibid.

(11.) B Shapiro, M D Gross, "Endocrine crisis: Pheochromocytoma," Critical Care Clinics 7 (January 1991) 1-21.

(12.) N L Benowitz, "Diagnosis and management of pheochromocytoma," Hospital Practice 25 (June 15, 1990) 163-170, 173-174, 177.

(13.) Feldman, "Diagnosis and management of pheochromocytoma," 178.

(14.) Benowitz, "Diagnosis and management of pheochromocytoma," 165.

(15.) R W Gifford, Jr, W M Manger, E L Bravo, "Pheochromocytoma," Endocrinology and Metabolism Clinics of North America 23 (June 1994) 387-404.

(16.) Feldman, "Diagnosis and management of pheochromocytoma," 178.

(17.) Shapiro, Gross, "Endocrine crisis: Pheochromocytoma," 8.

(18.) Agana-Defensor, Proch, "Pheochromocytoma: A clinical review," 311.

(19.) Shapiro, Gross "Endocrine crisis: Pheochromocytoma," 8.

(20.) Ibid.

(21.) Agana-Defensor, Proch, "Pheochromocytoma: A clinical review," 311.

(22.) C M Hudak, B M Gallo, J J Benz, Critical Care Nursing: A Holistic Approach, sixth ed (Philadelphia: J B Lippincott Co, 1994) 320.

(23.) Gifford, Jr, Manger. Bravo, "Pheochromocytoma," 388-389.

(24.) Young, Jr, "Pheochromocytoma: A brief management guide." 67.

(25.) Shapiro, Gross "Endocrine crisis: Pheochromocytoma," 9.

(26.) Benowitz, "Diagnosis and management of pheochromocytoma," 199.

(27.) Agana-Defensor, Proch, "Pheochromocytoma: A clinical review," 313.

(28.) Ibid.

(29.) M A Baxter et al, "Pheochromocytomas as a cause of hypotension." Clinical Endocrinology 37 (September 1992) 304-306.

(30.) R M Berne, M N Levy, Physiology, third ed (St Louis: Mosby-Year Book, Inc, 1993) 976.

(31.) Benowitz, "Diagnosis and management of pheochromocytoma," 201, 204.

(32.) Ibid.

(33.) Young, Jr, "Pheochromocytoma: A brief management guide," 69.

(34.) Ibid.

(35.) Agana-Defensor, Proch, "Pheochromocytoma: A clinical review," 315.

(36.) Werbel, Ober, "Pheochromocytoma: Update on diagnosis, localization, and management," 137.

(37.) G R Peplinski, J A Norton, "The predictive value of diagnostic tests for pheochromocytoma," Surgery 116 (December 1994) 1101-1109.

(38.) K L Becker et al, Principles and Practice of Endocrinology and Metabolism (Philadelphia: J B Lippincott Co, 1990) 675, 678.

(39.) Gifford, Jr, Manger, Bravo, "Pheochromocytoma," 395.

(40.) Benowitz, "Diagnosis and management of pheochromocytoma," 168.

(41.) Agana-Defensor, Proch, "Pheochromocytoma: A clinical review," 316.

(42.) D C Howard, Jr, "Pheochromocytoma in the pregnant patient: A case study," American Journal of Critical Care 1 (September 1992) 111-114.

(43.) Feldman, "Diagnosis and management of pheochromocytoma," 188.

(44.) Shapiro, Gross, "Endocrine crisis: Pheochromocytoma," 11.

(45.) Benowitz, "Diagnosis and management of pheochromocytoma," 170.

(46.) Werbel, Ober, "Pheochromocytoma: Update on diagnosis, localization, and management," 140.

(47.) S Maree, N Curll, P Emerson, "Anesthetic management of patients with pheochromocytomas: A report of three cases," CRNA 4 (August 1993) 133-141.

(48.) Shapiro, Gross "Endocrine crisis: Pheochromocytoma," 13.

(49.) Feldman, "Diagnosis and management of pheochromocytoma," 189.

(50.) Agana-Defensor, Proch, "Pheochromocytoma: A clinical review," 317.

(51.) L S Harkins, C Nygren, J C Rothrock, "Pediatric surgery," in Alexander's Care of the Patient in Surgery, 10th ed, M H Meeker, J C Rothrock, eds (St Louis: Mosby-Year Book, Inc, 1995) 1147.

(52.) Shapiro, Gross "Endocrine crisis: Pheochromocytoma," 15-16.

(53.) J L Hoffer, "Anesthesia," in Alexander's Care of the Patient in Surgery, 10th ed, M H Meeker, J C Rothrock, eds (St Louis: Mosby-Year Book, Inc, 1995) 177.

(54.) C W Bardin, Current Therapy in Endocrinology and Metabolism, fourth ed (Philadelphia: B C Decker Inc, 1991) 156; Maree, Curll, Emerson, "Anesthetic management of patients with pheochromocytomas: A report of three cases," 139.

(55.) G M Nagle, "Genitourinary surgery," in Alexander's Care of the Patient in Surgery, 10th ed, M H Meeker, J C Rothrock, eds (St Louis: Mosby-Year Book, Inc, 1995) 544.

(56.) E D Staren et al, "Surgical intervention for pheochromocytoma," AORN Journal 44 (November 1986) 758-765.

(57.) Nagle, "Genitourinary surgery," 545.

(58.) D C Sabisten, Jr, Textbook of Surgery: The Biological Basis of Modern Surgical Practice (Philadelphia: W B Saunders Co, 1991) 650.

(59.) J A Van Heerden et al, "Longterm evaluation following resection of apparently benign pheochromocytoma(s)/paraganglioma(s)," World Journal of Surgery 14 (May/June 1990) 325-329.

(60.) Bardin, Current Therapy in Endocrinology and Metabolism, fourth ed, 157.

(61.) F E Karet, M J Brown, "Pheochromocytoma: Diagnosis and management," Postgraduate Medical Journal 70 (May 1994) 326-328.

(62.) Werbel, Ober, "Pheochromocytoma: Update on diagnosis, localization, and management," 147.

(63.) Benowitz, "Diagnosis and management of pheochromocytoma," 215.

(64.) Gifford, Jr, Manger, Bravo, "Pheochromocytoma," 389.

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