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Phaeochromocytoma causing acute pulmonary oedema during emergency caesarean section.

SUMMARY

We report a case of severe acute pulmonary oedema following induction of general anaesthesia for emergency caesarean section. After several hours of aggressive resuscitation, both mother and child had a favourable outcome. Postoperative investigation of acute renal failure demonstrated a supra-adrenal mass. Further investigation confirmed bilateral phaeochromocytoma as the cause of her condition. A literature review confirmed this to be a rare but important clinical entity, owing to its high mortality. Antenatal diagnosis greatly improves survival. Magnesium sulphate appears to be a useful and safe agent to employ in cases of undiagnosed hypertensive obstetric emergencies.

Key Words: pregnancy, caesarean section, complications, acute pulmonary oedema, phaeochromocytoma

CASE HISTORY

A 33-year-old gravida-5, para-3 woman at 36 weeks gestation presented to a large peripheral hospital with a severe headache and associated episodic hypertension. Her past history included radio-frequency ablation for Wolff-Parkinson-White syndrome and a spontaneous right parietal subarachnoid haemorrhage (SAH) two years prior. At the time of her SAH she was investigated for an intracerebral aneurysm or arteriovenous malformation and no underlying structural abnormality was detected. Thereafter she was treated for essential hypertension. No primary cause for hypertension was detected at this stage and she had normal renal function and normal body habitus. Pharmacotherapy was commenced using atenolol 25 mg daily, but this was changed to methyldopa 250 mg twice daily following conception.

Her antepartum course was complicated by labile blood pressure (BP), with recordings varying from 110/60 mmHg to 200/100 mmHg. Methyldopa was ceased due to symptomatic hypotension. Home BP monitoring (using an automated oscillometric device) demonstrated episodes of marked hypertension associated with "feelings of deafness" and severe "throbbing" occipito-parietal headaches. It was noted during antepartum visits that there were "conflicting blood pressure measurements at home, compared with in hospital".

The patient was admitted at 1330 hours with a severe headache which was associated with extreme anxiety and she stated that she "felt like (she) was going to die". The headache was episodic, lasting five to ten minutes. The BP varied from 120/80 to 150/90 mmHg. On examination, she had no peripheral oedema, mild proteinuria and the neurological examination was unremarkable, with normal fundi. A cardiotocograph was normal and reactive. Her initial blood analysis revealed a haemoglobin of 140 g/1, a white cell count of 11.8 x [10.sup.9]/1 and a platelet count of 212X[10.sup.9]/1. All electrolyte levels were unremarkable, her serum creatinine was 53 [micro]mol/l and uric acid 0.35 mmol/l.

At 1800 hours her BP was recorded at 200/80 mmHg and two hours later had fallen to 115/75 mmHg without intervention. After a further 30 minutes her BP was 215/115 mmHg which led the treating team to consider anxiety as the likely aetiology due to the episodic fluctuations in BP Again, the BP reduced to 150/95 mmHg after another two hours. In view of the possible diagnosis of pre-eclampsia (despite normal pathology and relatively minimal proteinuria), hourly blood pressure measurements were taken and the patient remained in hospital.

At 0205 hours (14 hours after presentation) the patient was found in a post-ictal state. Her BP was 130/90 mmHg, heart rate was 85 beats per minute (bpm) and arterial haemoglobin oxygen saturation (Sp[O.sub.2]) was 91%. She was noted to have frothy pink sputum and a bitten tongue. A fetal cardiotocograph showed reduced variability and tachycardia. Empirical antibiotics were administered for suspected aspiration. After a period of stabilisation with oxygen via a Hudson mask and insertion of intravenous cannulae, a working diagnosis of eclamptic seizure was made. Magnesium sulphate (MgS[O.sub.4]) therapy was commenced immediately (4 g loading dose followed by 1 g/h infusion) and the patient was transferred to the operating theatre for an emergency caesarean section.

Invasive blood pressure monitoring was commenced prior to induction via a radial artery catheter. The patient was anaesthetised using a rapid sequence induction with 500 mg sodium thiopentone, 100 mg suxamethonium and the trachea intubated at first attempt. Haemodynamic parameters were stable prior to induction, with systolic BP (SBP) of 115 mmHg, heart rate (HR) 105 bpm and Sp[O.sub.2] 95%. Within three minutes of induction, haemoserous fluid emerged from the tracheal tube and the Sp[O.sub.2] became unrecordable. Over two litres of fluid was intermittently suctioned from the endotracheal tube, manual ventilation was commenced, but apparent florid pulmonary oedema persisted.

Immediate caesarean section at 0453 hours delivered a female infant, weighing 2645g and with Apgar scores of 2 and 7 (at one and five minutes respectively), requiring brief oxygenation by mask only. Oxytocin (10 units intravenously) was administered for myometrial contraction. Frusemide 60 mg was administered and an infusion commenced at 100 mg/h. A diuresis of 200 ml was attained over two hours, whereafter the patient became anuric.

The first recorded Sp[O.sub.2], one hour after induction, was 79%. Arterial blood gas analysis 20 minutes after induction showed pH 7.06, Pc[o.sub.2] 63 mmHg, P[o.sub.2] 72 mmHg, HC[O.sub.3]-17 mmol/1, base excess -15.5 mmol/l and [S.sub.a] [O.sub.2] 82%. Ongoing efforts were made to maintain minute ventilation and encourage gas diffusion. Two hours later her condition continued to deteriorate with blood gas analysis showing pH 6.95, Pc[o.sub.2] 119 mmHg, P[o.sub.2] 41 mmHg, HC[O.sub.3]-25 mmol/l, base excess -11.9 mmol/1 and [S.sub.a] [O.sub.2] 45%. SBP remained greater than 140 mmHg during the initial period of hypoxia and there was persisting tachycardia above 120 bpm. In consultation with the tertiary retrieval service, sodium nitroprusside therapy was instituted (100 [micro]g/min). This resulted in immediate hypotension (SBP 90 mmHg). An adrenaline infusion commenced at 20 [micro]g/min, reducing to 5 [micro]g/min, normalised the blood pressure. MgS[O.sub.4], which had been ceased, was reinstituted at 1 g/h. Sodium bicarbonate infusions were commenced for severe acidosis. Three hours after induction, minute ventilation remained between 9 and 10 1/min with 5-10 cm[H.sub.2]0 positive end-expiratory pressure to maintain Sp[O.sub.2] between 90-95%.

The patient was stabilised haemodynamically after approximately four hours of intensive resuscitation. Due to the lack of facilities for extracorporeal membrane oxygenation and specialist intensive care physicians, an aerial-retrieval team arrived after six hours and the patient was transferred to a tertiary centre for further management. Arterial blood gas analysis prior to transfer was pH 7.39, Pc[o.sub.2] 39 mmHg, P[o.sub.2] 62 mmHg, HC[O.sub.3]-23 mmol/1, base excess -0.8 mmol/l and [S.sub.a] [O.sub.2] 91%.

Within 48 hours, the patient required haemofiltration for acute renal failure (creatinine 383 [micro]mol/1) and ongoing haemodynamic support for five days. Sodium nitroprusside therapy and metoprolol was employed for management of persisting hypertension and tachycardia. On day three, a transthoracic echocardiogram demonstrated a small left ventricle (3.2 cm diastolic diameter), with a marked increase in relative wall thickness and 36% fractional shortening. Troponin I level was 2.48 [micro]g/1 (normal 0-0.3), consistent with a hypertrophic cardiomyopathy.

A renal ultrasound performed two days after admission demonstrated a possible adrenal mass and necessitated further investigation. MIBG (iodine-131-meta-iodobenzylguanidine) nuclear medicine scan demonstrated two large foci of tracer uptake, one on either side of the abdominal midline, highly suggestive of phaeochromocytomas. Computed tomography confirmed a 7 x 5 x 4 cm lesion in the right adrenal area and a smaller 2 x 3 x 3 cm lesion adjacent to the left adrenal gland. Magnetic resonance imaging demonstrated T2 hyperintensity and a heterogenous appearance on T1-weighted images. Twenty-four hour urine catecholamine analysis confirmed the diagnosis of phaeochromocytoma. Noradrenaline excretion was 1993 nmol/day (normal 0-780) and serum noradrenaline 9020 pmol/l (normal 150-700).

Surgical resection was undertaken one month after stabilisation, after alpha-adrenoreceptor and subsequent beta-adrenoreceptor blockade. Due to intraoperative bleeding, a right nephrectomy was also performed. Postoperatively, blood pressure and urinary catecholamine secretion normalised and the patient was discharged from hospital without neurological or cardiovascular sequelae. Due to the synchronous nature of her lesions, genetic investigations were performed, diagnosing familial phaeochromocytoma and paraganglioma as a result of succinate dehydrogenase subunit-B mutation. At review six months after presentation she no longer required treatment for hypertension and both she and her child were well.

DISCUSSION

This case highlights the challenges presented by peripartum hypertension, as well as the potential precipitous nature of phaeochromocytoma in pregnancy.

Phaeochromocytoma is a catecholamine-secreting, neuroendocrine tumour arising from chromaffin cells. Lesions may arise sporadically or, in 10% of cases, as part of a genetic predisposition. Conditions associated with a propensity to phaeochromocytoma include multiple endocrine neoplasia (MEN) IIA and MEN IIB.

The clinical features of phaeochromocytoma are notoriously varied, hence the coined pseudonym of the "great mimic". Presenting features include episodic hypertension, headaches, anxiety, palpitations and tachycardia. Phaeochromocytoma presenting as cardiogenic shock is a recognised but uncommon event (1-4).

Phaeochromocytoma in the setting of pregnancy presents both a diagnostic and therapeutic challenge and poses a significant threat to maternal and fetal welfare. There are over 200 reported such cases in the literature (5). The time of diagnosis is the crucial determinant of maternal and fetal outcome. In a review of 42 cases, Harper et al (5) concluded an overall maternal mortality of 17% and fetal loss of 26%. When the phaeochromocytoma was diagnosed antenatally, maternal mortality was less than 1% and fetal demise 15%. However, in that series only 26% of phaeochromocytomas were diagnosed in this antenatal period. In an earlier series, Ellison et all reported that, if undiagnosed, the maternal and fetal mortality exceeded 50%. When diagnosed prior to delivery, maternal mortality was 40% and fetal mortality 10%.

Diagnosis in pregnancy is a clinical challenge. The usual finding of hypertension lends to the more common diagnosis of preeclampsia. Headache, agitation and anxiety often complicate the antepartum period and labour, and may be benign in nature or indicative of intracerebral pathology. Cardiovascular collapse may further complicate the diagnostic milieu, adding possible thromboembolic events. To add to the challenge further, the literature suggests that mortality is greater in post partum clinical presentations (5, 7).

The presumptive diagnosis of pre-eclampsia is a common finding in a review of the literature, with the importance of differentiating phaeochromocytoma being the difference in definitive management and haemodynamic effects of the two conditions. Preeclampsia is associated with proteinuria and hypertension, usually occurring after the 20th week of gestation, while phaeochromocytoma is rarely associated with proteinuria and may cause hypertension throughout pregnancy (8). In our case the extreme hypertension (systolic BP exceeding 200 mmHg at times), in the setting of relatively minor proteinuria, should have questioned the diagnosis of pre-eclampsia.

Lau et al reviewed three cases of phaeochromocytoma occurring in pregnancy and suggested that the diagnosis be considered in any pregnant woman with severe hypertension, particularly if presenting before 20 weeks gestation and associated with sweating, palpitations, headaches or a labile blood pressure (9). In retrospect, the fluctuations in blood pressure recordings during our patient's antenatal course were indicative of a phaeochromocytoma, the diagnosis being supported by the relative lack of proteinuria, despite severe hypertension, as well as significant anxiety and a sensation of impending doom. Bullough et al (10) described a similar case of post caesarean section pulmonary oedema with frothy secretions and labile blood pressure secondary to an undiagnosed phaeochromocytoma. In this case the diagnosis of pre-eclampsia was questioned due to the lack of oedema and significant proteinuria.

The traditional approach to the management of phaeochromocytoma is [alpha]-adrenergic blockade, followed by [beta]-blockade and definitive surgical resection. Controversy exists about management when diagnosed in the antepartum period (11). In the first trimester, management is difficult. A long-term medical approach confers significant risk to mother and child, whereas surgical resection after stabilisation is associated with 80% fetal loss (9). Schenker et al (11) advise that after the 24th week, the pregnancy should be allowed to continue under adequate adrenergic blockade until fetal maturity is achieved. Several case reports have described successful caesarean section and excision of tumour simultaneously at term, with favourable outcomes for mother and child.

Surges in catecholamine release may result in fatal hypertensive crises. In pregnancy such surges may be precipitated by induction of general anaesthesia, vaginal delivery, myometrial contractions, mechanical effects of the uterus or vigorous fetal movements. In our patient, induction of anaesthesia precipitated acute pulmonary oedema secondary to acute left ventricular failure. Left ventricular dysfunction secondary to chronic catecholamine exposure is a well-reported pathophysiological process. Cermakova et al (13) described a patient who developed severe acute pulmonary oedema and fluctuating BP three hours post partum. The clinical picture was that of hypotension and cardiac failure. Post mortem examination revealed a phaeochromocytoma as the cause of her demise. The decision to use alpha blockade in the management of phaeochromocytoma is a difficult one in the setting of haemodynamic instability and cardiac failure requiring adrenaline infusion. In a recent report, five of six patients with phaeochromocytoma who developed pulmonary oedema died within 24 hours of the acute event (14). The precise pathogenesis of catecholamine-induced myocardial dysfunction is not fully elucidated. It has been suggested that calcium-induced myocyte injury occurs due to increased trans-sarcolemmal calcium flux, leading to myocardial necrosis. Others suggest a role of [alpha]-adrenergic-mediated coronary vasoconstriction causing myocarditis (1, 15). Given the poorly understood pathophysiology and the wide variety of haemodynamic responses, management protocols vary accordingly.

In our case the inability to obtain an accurate reading from the pulse oximeter may have been due to the very narrow pulse pressure owing to a diastolic pressure of greater than 100 mmHg. Hydralazine was not employed to treat hypertension in view of the severe pulmonary oedema and the perceived benefit of venodilation provided by a nitrate. Although the cardiovascular effects of oxytocin may have complicated the haemodynamic picture, at the time there was no evidence of hypotension and the decision was made to administer the oxytocic. Three hours of aggressive resuscitation in the setting of severe metabolic derangements were required prior to stabilisation using adrenaline and MgS[O.sub.4] infusions.

Magnesium is commonly used to prevent seizures and control blood pressure among patients with pre-eclampsia. Other advantages include direct-acting vasodilation, inhibition of catecholamine release from the adrenal medulla, reduction in sensitivity of [alpha]-adrenergic receptors to catecholamines and a potent antiarrhythmic effect (11). The plasma levels required to exert these effects appear to be in the range of 2.5 to 4.0 nmol/l (16). All these effects are of benefit in a patient with a phaeochromocytoma. This is particularly advantageous given the frequently indistinguishable clinical picture of these two conditions. MgS[O.sub.4] has also been demonstrated to control phaeochromocytoma crises and smooth haemodynamic parameters during resection". In these reports, boluses (2 to 4 g) were given pre-induction or during the crises, and infusions at 1 to 3 g/h titrated to effect.

Allen et al demonstrated the attenuation of the pressor response to intubation in hypertensive proteinuric pregnant patients using MgS[O.sub.4] (40 mg/kg bolus dose) (18). Although a MgS[O.sub.4] infusion had already commenced prior to cardiovascular collapse in our patient, we theorise that magnesium therapy played a major role in the successful outcome. Similarly, Bullough et al (9) attributed a successful outcome to the use of MgS[O.sub.4]. In another series of 17 patients with phaeochromocytoma (including two pregnant patients) where magnesium was the primary therapeutic agent used, magnesium controlled the BP except during tumour manipulation or when levels were subtherapeutic (16).

The hypertensive parturient can present a major clinical challenge and while preeclampsia is a common and important cause, the possibility of phaeochromocytoma should not be ignored. It appears that magnesium therapy is of potential value in these patients where there is uncertainty as to the aetiology of the hypertension.

Accepted for publication on January 25, 2007.

REFERENCES

(1.) Kim J, Reutrakul S, Davis DB, Kaplan EL, Refetoff S. Multiple endocrine neoplasia 2A syndrome presenting as peripartum cardiomyopathy due to catecholamine excess. Eur J Endocrinol 2004; 151:771-777.

(2.) Hudsmith JG, Thomas CE, Browne DA. Undiagnosed phaeochromocytoma mimicking severe preeclampsia in a pregnant woman at term. Int J Obstet Anesth 2006; 15:240-245.

(3.) Gill PS. Acute heart failure in the parturient--do not forget phaeochromocytoma. Anaesth Intensive Care 2000; 28:322-324.

(4.) Grodski S, Jung C, Kertes P, Davies M, Banting S. Phaeochromocytoma in pregnancy. Intern Med J 2006; 36:604-606.

(5.) Harper MA, Murnaghan GA, Kennedy L, Hadden DR, Atkinson AB. Phaeochromocytoma in pregnancy. Five cases and a review of the literature. Br J Obstet Gynaecol 1989; 96:594-606.

(6.) Ellison GT, Mansberger JA, Mansberger JR. Malignant recurrent phaeochromocytoma during pregnancy: Case report and review of the literature. Surgery 1988; 103:484-489.

(7.) Botchan A, Hauser R, Kupferminc M, Grisaru D, Reuben Peyser M, Lessing JB. Phaeochromocytoma in pregnancy: case report and review of the literature. Obstet Gynecol Surv 1995; 50:321-327.

(8.) Dugas G, Fuller J, Singh S, Watson J. Phaeochromocytoma and pregnancy: a case report and review of anesthetic management. Can J Anesth 2004; 51:134-138.

(9.) Lau P, Permezel M, Dawson P, Chester S, Collier N, Forbes I. Phaeochromocytoma in pregnancy. Aust NZJ Obstet Gynaecol 1996; 36:472-476.

(10.) Bullough AS, Karadia S, Watters M. Phaeochromocytoma: an unusual cause of hypertension in pregnancy. Anaesthesia 2001; 56:43-46.

(11.) Hamilton A, Sirrs S, Schmidt N, Onrot J. Anaesthesia for phaeochromocytoma in pregnancy. Can J Anaesth 1997; 44:654-657.

(12.) Schenker JG, Granat M. Phaeochromocytoma and pregnancy--an updated appraisal. Aust N Z J Obstet Gynaecol 1982; 22:1-10.

(13.) Cermakova A, Knibb AA, Hoskins C, Menon G. Post partum phaeochromocytoma. Int J Obstet Anesth 2003; 12:300-304.

(14.) Sardesai SH, Mourant AJ, Sivathandon Y, Farrow R, Gibbons DO. Phaeochromocytoma and catecholamine induced cardiomyopathy presenting as heart failure. Br Heart J 1990; 63:234-237.

(15.) Lee JC, Sponenberg DP Role of al-adrenoceptors in nore-pinephrine-induced cardiomyopathy. Am J Path 1985; 121:316-321.

(16.) James MFM, Huddle KRL, Owen AD, van der Veen BW Use of magnesium sulphate in the anaesthetic management of phaeochromocytoma in pregnancy. Can J Anaesth 1988; 35:178-182.

(17.) James MF, Cronje L. Pheochromocytoma crisis: the use of magnesium sulfate. Anesth Analg 2004; 99:680-686.

(18.) Allen RW, James MFM, Uys PC. Attentuation of the pressor response to tracheal intubation in hypertensive proteinuric pregnant patients by lignocaine, alfentanil and magnesium sulphate. Br J Anaesth 1991; 66:216-223.

J. R. GOLSHEVSKY *, K. KAREL ([dagger]), G. TEALE ([double dagger])

Department of Anaesthesia, Goulburn Valley Health, Shepparton, Victoria, Australia

* M.B., B.S. (Hons), Anaesthetic Registrar, Department of Anaesthetics, St Vincent's Hospital, Melbourne.

([dagger]) M.B., B.S., F.R.C.A., F.A.N.Z.C.A., Consultant Anaesthetist, Goulburn Valley Health.

([double dagger]) M.B., B.S., B.Sc., M.R.C.P, M.R.C.O.G., M.D., F.R.A.N.Z.C.O.G., Director, Department of Obstetrics and Gynaecology, Goulburn Valley Health, Shepparton.

Address for correspondence: Dr J. Golshevsky, Department of Anaesthesia, St Vincent's Hospital, 41 Victoria Pde, Fitzroy, Vic. 3065. Jonathan.Golshevsky@svhm.org.au
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Author:Golshevsky, J.R.; Karel, K.; Teale, G.
Publication:Anaesthesia and Intensive Care
Article Type:Clinical report
Geographic Code:8AUST
Date:Jun 1, 2007
Words:3214
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