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Published by : PROFESSIONAL MEDICAL PUBLICATIONS |
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ISSN 1681-715X |
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continuing medical education |
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Volume 21 |
October December 2005 |
Number 4 |
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Published by : PROFESSIONAL MEDICAL PUBLICATIONS |
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ISSN 1681-715X |
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continuing medical education |
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Volume 21 |
October December 2005 |
Number 4 |
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Pheochromocytoma associated with Pregnancy:
Anaesthetic ManagementFaraz Shafiq1
1. Dr. Faraz Shafiq MBBS
Postgraduate Student,
Department of Anaesthesia,
Aga Khan University Hospital, KarachiCorrespondence:
Dr. Faraz Shafiq,
Mail: farazshafiq@yahoo.comReceived for Publication: May 31, 2005
Accepted: October 5, 2005
Introduction
Pheochromocytomas are the tumor of neural crest cells of adrenal gland secretes Catecholamines (norepinephrine being greater than epinephrine). It causes hypertension in 0.1% of cases.1 80-90 % are solitary tumors localized to single adrenal gland usually right side while 10% are bilateral. They may originate any where in neural crest side from neck to inguinal ligament e.g. right atrium, spleen, broad ligament of ovary, vagina, bifurcation of aorta and in 10% of cases it is inherited as familial autosomal dominant trait. In such cases it is associated with Men 2a, 2b,2 Von hippel disease3 and neurofibromatosis.
Pheochromocytoma in Pregnancy
It is a rare complication of pregnancy but it is life threatening when it does exist. The exact prevalence in pregnancy is impossible to determine but somewhat more than two hundred cases have been reported.4 Association of tumor with pregnancy cause significant risk for both mother and fetus. Risk of maternal death is 40%, abortion is likely in 12%, intra uterine death in 23%, while the overall fetal loss may be up to 50%.5
Clinical Presentation: Pheochromocytoma with pregnancy is a protean disease that makes it both difficult and challenging to recognize.6 Signs and symptoms basically depend upon the predominant secreting harmone. Norepinephrine secreting pregnant patients mostly present a paroxysmal symptoms of hypertension 80-85%, headache 65-70%, palpitation 35-40%, sweating 30-35%, blurred vision 18-20% and anxiety 15%.5 Epinephrine secreting tumors present as episodic syncope, faintness and weakness. Most of these signs and symptoms are also present in normal pregnancy, so the first thing to diagnose this in pregnancy is to have a high index of clinical suspicion.
Other modes of presentation include myocardial infarction,7 heart failure, dysrrythmias, cardiomyopathy,8 and malignant hyperthermia.9
Diagnosis: The two main stay of diagnosis are biochemical testing to find out increase in level of harmones and their metabolites and imaging techniques to find out the localization of tumors.
Biochemical tests are most commonly used to establish the diagnosis of Pheochromocytoma.10 Measurement of urinary catecholamines and their metabolites metanephrine, normetanephrine, vaniyl mandellic acid and measurement of plasma level of catecholamines are the commonly performing tests. While Ultra sonogrphy, CT scanning, Metaiodobenzylguanidine scanning and MRI are the commonly used imaging techniques.
Treatment: For pregnant patients presenting at or near term, tumor can be treated medically by using alpha-adrenergic blockage. Phenoxybenzamine (PBZ) is usually the initial drug of choice. It is a non-competitive long acting alpha adrenergic receptor blocker. Usually it is given orally but can be given intravenously in case of emergency situations. Beta-blockers have a role in predominating epinephrine secreting tumors or in the prevention of secondary arrhythmias after proper alpha blockage. The definite treatment is surgical resection of tumor and in cases of pregnancy it can be resected during first trimester or at the time of caesarian section.5 Maternal mortality is decreased with caesarian section as compared to vaginal delivery.5
Anaesthetic Considerations: Pheochromocytoma associated with pregnancy is a life threatening condition. Mortality rate decreases when the anesthetist knows the condition preoperatively. In fact 25-50% of hospital deaths with pheochromocytoma occur during induction of anesthesia for other disorders.
Preoperative Evaluation: Along with routine preoperative assessment including history, previous surgeries, drugs history, proper examination one should specially look for:
* Adequacy of alpha blockage judged by resting BP, orthostatic hypotension and heart rate.
* Signs of CHF, cardiomyopathy, ventricular ectopics, EKG evidence of ischemia and specially intra vascular volume status.
* Treatment with PBZ for 10-14 days is usually required to achieve adequate alpha block. However 3-5 days therapy has also been reported.11
Investigations: It includes routine tests like hemoglobin, hematocrit, electrolytes, urea, creatinine, chest Xray and EKG while other tests like echocardiography, stress test, etc. depend upon overall condition of the patient.
Preoperative medications: Patient should continue alpha blocking and other anti hypertensives till the day of surgery.
Aspiration prophylaxis has a major role in term of pregnancy.12
The following criteria shows the optimal preoperative condition for such patients
* No hospital reading of BP higher than 160/90mmHg for 24 hours before surgery.
* Orthostatic hypotension with readings above 80/45 mmHg should be present.
* The patient should have no more than one PVC every five minutes
* The EKG should be free of ST-T abnormalities.
Proper preoperative assessment is essential as it is associated with reduction in maternal as well as fetal out come.13
Choices of Anaesthesia: Choices are between sub-arachnoid block alone or in combination with epidural analgesia or general anesthesia along with control mode of ventilation. Regional techniques are useful in blunting stress response to surgeries, anticoagulating effects, problems associated with intubation extubation can be avoided, prolonged pain relief but again it should be kept in mind that it can lead to sypathectomy which can cause dangerous hypotension in such patients. General anesthesia is usually associated with adrenergic responses during intubation and extubation, which may be harmful in such patients.
Monitoring: Saturation pressure of Oxygen, EKG, temperature, Pulse rate are the routine standards of modern anesthesia practice, while invasive blood pressure, CVP, Pulmonary artery catheter (in case of cardiac pathology) are used in case of secondary pathologies.
Maintenance: It is important to ensure:
* Adequate level of anesthesia and analgesia should be maintained during induction and maintenance.
* Avoid unnecessary compression of abdomen as in 50% of patients it is associated with increase in BP.
* Intraopeartive use of Sodium nitroprusside 3 microgram per Kg to maximum 800 micro gram per min for control of cardiovascular status.
* Use of Magnesium sulphate 2-2.5 gram per minute for its cardiostable effects.14
* Ketamine, suxamethonium and pancuronium should be avoided because of their effects on cardiovascular system.
Post Operative Management: Proper pain management has important role in such patients and the choice lies in narcotic infusions, patient controlled intravenous analgesia and epidurally administered infusions.
Postoperative BP control is very important, as 50% of patients remain hypertensive for 3-4 days and cateholamines level usually returns to normal within 10 days.
References
1. Kaplan NM. Clinical Hypertension. 5th edition. Batimore: William and Wilkins 1990: 1-25.
2. Epstein H, MoreHouse M, Cowles T, King CR. MEA 3 presenting as pheochromocytoma and complicating pregnancy and puerperium. J Reprod Med 1985; 30: 501-4.
3. Gross DJ, Arishai N, Meinerv, Filon D, Abeliovich D. Familial Pheochromocytoma associated with novel mutation in von hippel - lindau gene. J Clin Endocrinol Metab 1996; 81: 147-9.
4. Cherry, Merkatzs. Complication of pregnancy, Fifth edition. WR Cohen and James B young lippincott William and wilkin, Philadelphia 2000: 435-37.
5. Schenker JG, Chavers I. Pheochromocytoma and pregnancy. An updated appraisal. Aust NZ J Obstet Gynaecol 1982; 22: 1.
6. Monkelban JF, Cats Haenhout CH, Dullaart RPF, van Haefblun TN. Pheochromocytoma in various disguises. Neth J Med 1995; 47: 76.
7. Jessrun CR, Adam K Moise K , Wilansky S . Pheochromocytoma induced myocardial infarction in pregnancy. Tex Heart Inst J 1993; 20: 120-2.
8. Nanda AS, Feidman A, Liang C. Acute reversal of pheochromocytoma induced catecholamine cardiomyopathy. Clin Cardiol 1995; 15: 421-3.
9. Allen C, RosenBurg H. Pheochromocytoma presenting as acute malignant hyperthermia, a diagnostic challenge. Can J Anaesthesia 1997; 37: 593.
10. GiffidRW Jr, Manger Wm, Bravo EI, Pheochromocytoma. Endocrinol Meatab Clin North Am 1994; 23: 387.
11. Russel WJ, MetercalleIR, Flewen DB: the preoperative management of Pheochromocytoma Anesth Intensive Care 1998; 26: 196.
12. Egbert lD, Battit BE Turnorf H. The value of preoperative visit by anaesthetist. JAMA 1963; 185: 553.
13. Desmont JM, Le Houeller J, Remond P. Anaesthetic management of patient with Pheochromocytoma , Br Jour Anaes 49 : 991.
14. Drolet PM. The use of magnesium sulphate during surgery of Pheochromocytoma. Can J Anaes 1993; 40: 521.
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