INTERNATIONAL JOURNAL OF CLINICAL AND MEDICAL CASES (ISSN:2517-7346)

The diagnosis and management of pheochromocytoma in renal failure patients requires scrupulous preparations due to the challenges its excision poses in terms of estimating and managing intravascular volume and vascular tone. This report summarizes the perioperative management of a 24-year old patient on haemodialysis who underwent open adrenalectomy for a ginormous unilateral pheochromocytoma, in order to provide reference to managing similar cases. The tumour presented as a suspicious mass during random imaging and was confirmed by clinical, CT scan and serum catecholamine by-product assay data. Large tumour size, arduous surgery and strong functional activity resulted in near haemodynamic collapse in spite of reasonable preoperative optimization. The ability of FloTrac monitoring system to reflect and assess circulatory changes and to guide fluid and vasopressor usage was also analyzed and presented.

Pheochromocytoma; Adrenalectomy; ESRD; Vasopressor; Systemic Vascular Resistance; Cardiac Output

Pheochromocytoma (PCC) is a rare catecholamine (CA) secreting chromaffin tissue tumour, occurring in less than 0.5% of patients with hypertension (HTN) [1]. About 30 percent of PCC occur in association with familial neuroendocrine syndromes (MEN), while majorities are sporadic. Roughly 10–40% of these tumours are found incidentally and the classic symptomatology, i.e., paroxysmal HTN, palpitation and diaphoresis is present in only 40% of the cases. These tumours may secrete epinephrine (E), norepinephrine (NE), or dopamine in either a continuous manner (leading to sustained HTN) or episodic pattern (leading to paroxysms of symptoms). Surgery, wherever feasible, is the treatment of choice for these tumours with diligent preoperative optimization involving vascular expansion and control of HTN[2].The true incidence of PCC in patients with end stage renal disease (ESRD) is unknown and considered exceedingly uncommon. Most data on the anaesthetic management and perioperative outcomes have been reported in small case series, consequently there is obscurity in diagnosis, preparation, and intra operative monitoring. In addition to perplexity associated with ESRD patient’s volume status, it remains unclear whether fluid deficit or vasoplegia causes shifting haemodynamics intraoperatively, while appropriate targets remain unclear. We report peri-operative management of a 24- yrs old gentleman known case of ESRD on maintenance haemodialysis (HD) who underwent open adrenalectomy and nephrectomy for a large PCC. We utilized FloTrac device (4^thgeneration, version 4; Edwards Life science, Irvine, CA, USA) to titrate timing and infusions of volume and vasopressors to respond to rapid changes in intra-operative haemodynamics.

A 24 years old gentleman known ESRD of unknown cause, on irregular maintenance HD for 4 years was referred to surgical oncology for a suspicious right adnexal mass identified during ultrasound imaging for prospective renal transplantation evaluation. His other comorbidities were HTN, subclinical thyrotoxicosis and anaemia. His drug therapy included Injdarbepoetin 40mcg SC twice a week, tab isolazine (isosorbide dinitrate/hydralazine) 20/37.5mg half hs, tab amlodipine 5 mg bd, tab bisoprolol 2.5mg od, tab sodium bicarbonate 1gm tds and tab prazosin 2.5mg bd. His symptoms included occasional headache, palpitation, and dizziness on exertion since 17 years of age which the treating physician attributed to chronic renal failure. There was no associated family history of renal disease, HTN, thyroid cancer or any other features suggesting familial diseases. His effort tolerance was NYHA class 2 with no prior hospitalizations. On clinical examination he was pale, afebrile, pulse rate 82/min regular, blood pressure (BP) 170/90mmHg respiratory rate 20/min, height 174 cms and weight 66kg (post HD). Abdominal examination revealed vague fullness in right hypochondrium and shifting dullness. Abdominal CT and wholebody PET-CT scan disclosed a large intensely hyper metabolic lobulated soft tissue density lesion measuring 12X10.5X11.5 cm with central hypometabolism (necrosis) in the right supra renal region, indenting inferior vena cava (IVC) and uncinate process of pancreas; and displacing right kidney posteroinferiorly(Figure 1). This heterodense vascular mass was not visualized separately from adrenal gland with few suspicious enlarged celiac and paraaortic lymph nodes without any distant metastasis. Bilateral contracted kidneys, cardiomegaly, mild pericardial effusion, moderate intraperitoneal free fluid and normal thyroid gland were also noted. Ascitic fluid tapping and cytology was performed which ruled out malignancy. Electrocardiogram demonstrated left axis deviation with “T” wave flattening in inferior leads, and recent transthoracic echocardiography revealed concentric left ventricular (LV) hypertrophy, global hypokinesia, tricuspid regurgitation, ejection fraction of 45%, grade 2 diastolic dysfunction, dilated left and right atrium with mildly dilated ventricles. Laboratory data revealed elevated serum metanephrine levels (Table 1). Serological and imaging evaluation for MEN related endocrine tumours were negative.

With provisional diagnosis of PCC the patient was planned for open right adrenalectomy with radical nephrectomy due to giant size of tumour. A multidisciplinary team of anaesthesiologist, nephrologist, surgeon and endocrinologist was formed to prepare a plan of optimization and treatment.

Anaesthesia

In the operation theatre HD arteriovenous access in the left forearm (brachio-cephalic fistula) was duly protected. Baseline heart rate (HR) was 68/min, BP 154/92mmHg and oxygen saturation 98%. 2gm intravenous magnesium sulphate in 100ml saline bolus was administered over 30 minutes followed by 500mg/hour infusion. Epidural catheter was placed at thoracic 7-8 level and gradual incremental 6ml bolus of bupivaicaine 0.25% was administered; while right radial artery was catheterised under local anaesthesia. General anaesthesia was induced with fentanyl 3 mics/kg with titrated propofol and rocuronium. After adequate depth of anaesthesia gentle endotracheal intubation was performed with 10 % lignocaine spray on vocal cords; and right subclavian vein was cannulated. BP fluctuations were managed by intravenous nitroglycerine, esmolol and propofol boluses as indicated. After intubation, a tidal volume of 8 mL/kg of the patients’ ideal body weight was set, with a respiratory rate of 10 -12 bpm to maintain normocapnia.

Haemodynamic monitoring

The FloTrac device was attached to the arterial canula after surgical scrub and connected to the EV 1000 monitor (version 1.9, Edwards Life Science, Irvine, CA, USA).Information collected included HR, invasive arterial blood pressure (IBP), stoke volume variation (SVV), systemic vascular resistance (SVR), central venous pressure (CVP), anaesthetic and surgical events apart from routine monitoring. Baseline indices noted were SVR 3500dynes/ sec/cm-5, C.O 2.5 L/min, IBP 130/84mmHg, end tidal CO2 36mmHg, and cvp 9 cm (after ascites release). Intraoperatively we managed the intravenous fluid volume with SVV, cvp and ongoing losses obtained and assessed the fluid responsiveness clinically too. Vasopressors and vasodilators were initiated and adjusted as per SVR, systolic and diastolic bp as required. We didn’t have predefined strict targets since the BP instability and swings were expected to be quite unpredictable; instead tried to attain acceptable range of haemodynamics indices.

Operation

Surgery was performed in supine position with a modified Makkuchi insicion 2.0 L ascites was drained and replaced by intravenous albumin. It was a large vascular tumour occupying and encasing predominantly the upper pole of right kidney, indenting IVC and adherent to capsule of liver and diaphragm (Figure 2). As surgeon started ligating multiple small feeder vessels, IBP remained stable but gradually SVR reduced to 876 dynes.sec. cm-5 and C.O increased to 7.5 L/min. At this stage magnesium infusion and nitroglycerine infusions were discontinued. With further fall in BP and SVR, NE infusion was initiated. One moment during tumour mobilization IVC got compressed resulting in unexpected drop in BP and CO which reverted swiftly when compression was released. Finally, ligation of major feeder veins resulted in profound persistent hypotension requiring escalating doses of NE 27mcg/min, E 2mcg/min and vasopressin 2U/hr infusions gradually along with fluid boluses(Figure 3).Surgery lasted for 7 hours with approximate blood loss of 1.5 L. Patient received 4 units of packed cells, 2 unit of plasma,1 L of gelatin, 4.0 L of crytalloid and 200 ml of 20% albumin.

Post-Operative

Due to intense vasoplegia, metabolic acidosis and persistent hypotension patient was not extubated and ventilated overnight post-operatively (PO). Hypoglycemia and acidosis were managed by intravenous dextrose and bicarbonate infusions. Persistent low IBP resulted in thrombosis of the brachio-cephalic vascular access, in consequence we inserted internal jugular dialysis catheter as HD access. Gradually vasopressin and E infusions were weaned off first followed by NE infusion to 5mcg/min by PO 16 hrs and discontinued after PO 23 hrs. Ventilator was liberated at PO 18 hrs along with CO monitoring.On POday-1 slow low efficiency dialysis was performed for high potassium (6.6 Meq/L) and residual acidosis with 600 ml ultrafiltrate removal only. Next day oral liquid diet and epidural analgesia were initiated and intravenous fluids discontinued by evening. Following POday-3 drains, urinary catheter, arterial line and nasogastric tube were withdrawn and routine maintenance HD initiated. On POday-4, low dose anti HTN (tab bisoprolol 2.5mg OD and prazosin 2.5mg bd) were commenced as BP started gradually escalating. Patient was shifted to ward on day 5 and discharged on day 8. Histopathology reported adrenal tumour (17X11X7.5 cm) weighing 400 gm, conveying features of PCC with clear cell and spindle cell variants. Immunohistochemistry exhibited strong positivity for S-100, chromogranin and synaptophysin. Outpatient follows up after 3 months demonstrated reduced serum normetanephrines (156 pg/ml) and no evidence of tumour recurrence on CT scan. He is now listed and awaiting renal transplantation.