Pheochromocytoma

1. Pheochromocytoma Leah Olsson SRNA Rush University

2. ~Discuss physiology of pheochromocytomas and treatment ~Review: preoperative intraoperative postoperative treatment Objectives

3. Pheochromocytomas • Catecholamine secreting tumor of chromaffin tissues • Pheochromocytomas can be found anywhere chromaffin tissues exist

4. Dusky (pheo) Color (chromo) Pheochromocytomas produce store and secrete catecholamines epinephrine norepinephrine

5. Signs and Symptoms • HTN • Tachycardia • Diaphoresis • Headaches • Tremulousness • Weight loss • Palpitations • Orthostatic hypotension • (Stoelting & Dierdorf 2002)

6. Pheochromocytoma Triad • Diaphoresis • Tachycardia • Headaches

7. <0.5% of hypertensive patients are diagnosed with pheochromocytoma • Usually in patients 30-50 yrs. But can occur at any age. • Male=Female • (Nagelhout & Zaglaniczy, 2005)

8. Typically benign and unilateral. 10-15% are malignant 10-15% are bilateral (Morgan, Mikhail, & Murray, 2006)

9. Diagnosis • Blood catecholamine levels • Pheochromocytomas are found on CT and MRI.

10. Diagnosis • 24hr urine collection • free norepinephrine • tumor secretes catecholamines intermittently • catecholamines have a short half life. • (Stoelting & Dierdorf 2002)

11. Diagnosis • Vanillymandelic acid (VMA). • Final common product of both catecholamine metabolic pathways • Often used as an initial test r/t specificity and sensitivity. ↓ cost

12. Diagnosis • Clonidine suppression test: PO clonidine 0.3mg will suppress catecholamine secretion in hypertensive pts not in pt with pheochromocytomas • (Yao, Fontes, & Malhotra 2008 )

13. Treatment Surgical removal of the tumor Optimizing pt prior to surgery is most important for desirable surgical outcomes

14. Preoperative considerations • α-Adrenergic blockade should be started 10-14 days prior to surgery. • Phenoxybenzamine 10-20 mg qd. With increasing dose PRN • Decreases or prevents catecholamine-induced vasoconstriction. • Normalize BP and intravascular volume prior to surgery will assist in keeping the pt stable during resection of the catecholamine secreting tumor

15. Selective α1-blockers Prazosin and doxazosin Shorter DOA Easier dose adjustment ↓ postop hypotension ↓reflex tachycardia presynaptic α-receptors are not blocked α-blockade

16. If tachycardia persists then a beta blocker should be used. β blockade should only be administered if the pt is concurrently taking an αblocker. Unopposed α-mediated vasoconstriction has the potential to place the patient in CHF or can result cardiac arrest. Labetalol and atenolol Preoperative considerationsβ-blockers

17. Suggested drugs to avoid • Droperidol • Morphine • Atracurium • Pancuroium • Ketamine • Ephedrine • Halothane • Cocaine • Metoclopramide • Curare • (Yao, Fontes, & Malhotra 2008 )

18. Intraoperative management • Careful consideration should be taken when choosing drugs. • Stimulation of the SNS should be avoided • Premedicate pt to decrease anxiety! • A-line placed prior to induction. • PA cath +/- pt specific consider in pt with ↓ cardiac reserve, CHF • 2 Large bore IVs

19. Intraoperative considerations • Three critical phases of tumor resection are • 1) Induction and intubation • 2) Surgical manipulation • 3) After ligation of the tumors venous drainage • (Nagelhout & Zaglaniczy 2005)

20. Induction & Intubation • Etomidate, thiopental, and propofol can all be used to initiate anesthesia. • Increase anesthetic depth by bag mask ventilation with volatile anesthetic • Lidocaine 1-2mg/kg 1 min prior to induction • Narcotics • Fast acting antihypertensive readily available • (Nagelhout & Zaglaniczy 2005)

21. Maintenance • Anesthesia is maintained with gases and narcotics. VA are easy to titrate, can help with HTN (1.5-2 MAC) • Pt should be kept normovolemic. • Blood glucose monitoring

22. HTN Nipride gtt . Side effect: reflex tachycardia cyanide poisoning r/t ↑ infusion time Nicardipine gtt Hypotension volume expansion and decreased anesthetic gases (Stoelting & Dierdorf 2002) Indirect acting sympathomimetics should be avoided r/t unpredictable effects (Nagelhout & Zaglaniczy 2005) BP treatment

23. Ligation of the tumors venous drainage • ↓ circulating catecholamine causing hypotension • After ligation of all venous drainage arterial pressure commonly declines r/t ↑CO, ↓ SVR Treatment • ↓ VA • ↑ IVF • Phenylephrine or norepinephrine

24. Postop • Invasive lines should stay intact. Pt still at risk for liable BP. • Pt susceptible to hypotension that is refractory to fluid volume expansion.

25. Still have high volumes of circulating catecholamine despite tumor resection Catecholamine levels normalize after several days. 75% of pts BP returns to normal after 10 days (Nagelhout & Zaglaniczy 2005) Prone to Hypoglycemia. Secondary to suppression of β-cell function disappears after the tumor is removed (Yao, Fontes, & Malhotra 2008 ) Postop

26. Conclusion • Pheochromocytoma-physiology • Preoperative-pt optimization- proper pharmacologic tx • Intraoperative-induction-maintenance. Tx for liable BP

27. References • Morgan, G. E., Mikhail, M. S, Murray, M. J. (2006). Clinical Anesthesiology (4th ed.). New York: McGraw Hill. • Nagelhout, J. J., Zaglaniczny, K. L. (2005). Nurse Anesthesia (3rd ed.). St. Louis: Elsevier Sanders. • Yao, F. F., Fontes, M. L., Malhotra, V. (2008). Anesthesiology: problem oriented patient management (6th ed.). Philadelphia: Lippincott Williams & Wilkins. • Stoetling, R. K., Dierdorf, S. F., (2002). Anesthesia and Co-existing Disease (4th ed.). Philadelphia: Churchill Livingstone.