the effect of dexmedetomidine and magnesium sulfate in open resection of pheochromocytoma

Conditions: Pheochromocytoma

Summary: pheochromocytoma (pheo) is a catecholamine secreting tumor arising from chromaffin cells of the adrenal medulla in 90% of cases \& in 10% is extra-adrenal arising from the sympathetic chain. it is malignant in 10% of cases, bilateral in 10% of patients \& 10% of all pheo are inherited (familial pheo) as autosomal dominant either alone or as a part of multiple endocrine neoplasia (men) syndrome.in this prospective work, the investigators will try to compare the peri-operative hemodynamic course of dexmedetomidine \& magnesium sulphate (mgso₄) infused patients with the traditional anesthetic technique (α₁ \& β-adrenergic blockers plus vasodilators) during open surgical resection of pheo. the investigators are aiming to check the safety \& efficacy of the recommended technique on the peri-operative hemodynamic stability \& controlling the hypertensive crisis during tumor manipulation.

pheochromocytoma (pheo) is a catecholamine secreting tumor arising from chromaffin cells of the adrenal medulla in 90% of cases \& in 10% is extra-adrenal arising from the sympathetic chain. it is malignant in 10% of cases, bilateral in 10% of patients \& 10% of all pheo are inherited (familial pheo) as autosomal dominant either alone or as a part of multiple endocrine neoplasia (men) syndrome.the anesthetic management of pheo during surgical resection is usually challenging \& faces many cardiovascular risks as tachycardia, arrhythmias, severe hypertension \& may be pulmonary edema \& profound hypotension after surgical devascularization of the tumor. these dangerous events are sequelae of catecholamine excess and often are refractory to management . the proper anesthetic control is based on the use of α₁ \& β-adrenergic blockers (phenoxy-benzamine, phentolamine, propranolol, labetalol) and vasodilators such as glycerine trinitrate (gtn) \& sodium nitroprusside (snp) .the rational of using magnesium sulphate mgso₄ infusion to control catecholamine levels \& catecholamine-related crisis has been established in several clinical emergencies such as severe tetanus \& preoperative management of pre-eclampsia \& eclampsia . mgso₄ beneficial cardiovascular effects may be attributed to its ability to reduce catecholamine release from the adrenal medulla \& to reduce α-adrenergic receptors sensitivity to catecholamines . mgso₄ is also a direct vasodilator \& a potent anti-arrhythmic drug particularly with high circulatory catecholamine level . the safety of mgso₄ in the routine clinical range of 2-4 mmol/liter is well settled in many clinical works. there is strong evidence that the sympathetic nervous system is intact in pheo patients \& neurons-released noradrenaline plays a fundamental role in blood pressure bp regulation. dexmedetomidine is a short acting \& highly selective central α₂-agonist that inhibits neuronal firing \& thereby induces analgesia, anxiolysis, bradycardia \& hypotension. it has been tried to attenuate the sympathetic pressor effect of tracheal intubation, cardiac surgeries \& emergence from anesthesia .the unique adventitious anesthetic pharmacology induces preoperative sedation, intra-operative hemodynamic stability beside reducing the anesthetic requirements and adding to post-operative analgesia . its peri-operative use has been suggested in both pediatric \& adult patients of pheo. in this prospective work,the investigators tried to compare the peri-operative hemodynamic course of dexmedetomidine \& mgso₄ infused patients with the traditional anesthetic technique (α₁ \& β-adrenergic blockers plus vasodilators) during open surgical resection of pheo. the investigators are aiming to check the safety \& efficacy of this recommended technique on the peri-operative hemodynamic stability \& controlling the hypertensive crisis during tumor manipulation.

Eligibility criteria:
inclusion criteria: * age 12-69 years * asa physical status i \&ii * surgically diagnosed pheochromocytoma, "unilateral or bilateral, adrenal or extra-adrenal". diagnosis is confirmed radiologically with or without laboratory vanillyl mandelic acid (vma) level. * accepted echo-heart data (ef ≥ 55%, no serious valve lesion) apart from hypertensive concentric ventricular hypertrophy \& diastolic dysfunction grade i \&ii. exclusion criteria: * extremes of age * asa iii \& iv * history of cardiac (mi \& ihd) or cerebral (cvs) events * history of major reaction to the used drugs * history of major muscle, endocrinal or hematologic disorders * pregnant and lactating women * poor echo-heart findings e.g. ef \< 55%, severe valve lesions \& severe pulmonary hypertension.