Intra-operative haemodynamic volatility in a patient undergoing retroperitoneal cyst excision.

Excision of a suspected retroperitoneal, duodenal duplication cyst was performed in a pre-operatively normotensive patient under combined epidural and general anaesthesia. Intraoperatively, the cystic tumour was discovered to be a retroperitoneal mass, free from duodenal or adrenal origin. Development of severe arrhythmias, ST segment changes and hypertensive spikes during cyst handling and dissection suggested the possibility of a catecholamine-secreting tumour. These were managed effectively with pharmacological agents. Subsequently, histopathology of the specimen revealed a paraganglioma. Vasoactive tumour has to be suspected in every patient undergoing anaesthesia for retroperitoneal cystic lesion.

INTRODUCTION

Paragangliomas are rare neural crest tumours of sympathetic (generally catecholamine producing) or parasympathetic (rarely catecholamine producing) origin. The clinical picture is varied and diagnosis often difficult. Reports of unexpected paragangliomas suspected during excision or surfacing as histological surprises are rare. Anaesthesia and surgery in unsuspected cases have high mortality.[12] Emergency surgeries have been cancelled on table in patients demonstrating unstable haemodynamics during induction, and subsequent investigations confirmed the presence of a pre-operatively unsuspected pheochromocytoma.[3] In a post-mortem series, 27% of the patients with an undiagnosed pheochromocytoma died during or shortly after unrelated surgery.[12] Life-threatening events may follow resection in an unsuspected and, hence, unprepared patient with a retroperitoneal catecholamine-secreting tumour.[45] Paraganglioma in a haemodynamically asymptomatic patient, detected intraoperatively due to haemodynamic volatility, is a rare presentation, as in our case.

CASE REPORT

A 59-year-old female, 45 kg, with pain abdomen for 1 month and altered bowel habits (flatulence, bloating sensations) for 1 week, was diagnosed to have a retroperitoneal duodenal duplication cyst on computerised tomography (CT) [Figure 1] and posted for laparotomy and resection. She had no history of hypertension, diabetes or any other medical illness. She had undergone thyroid surgery 6 months back and was regularly on tab. Thyroxine 0.1 mg once a day. Her blood pressure was 130/80 mmHg. Routine blood and urine investigations, liver and thyroid function tests, electrocardiogram (ECG) and echocardiogram were normal.

Figure 1

High-resolution computed tomography scan showing tumour (0.625 mm retro reconstruction images were studied for diagnosis)

On the pre-operative night, tab. ranitidine 150 mg, tab. alprazolam 0.5 mg and tab. thyroxine 0.1 mg were advised. On the day of surgery, inj. pantoprazole 40 mg IV and maintenance fluids were infused. Combined low thoracic epidural with general anaesthesia (GA) was planned. An 18G thoracic epidural catheter was placed at the level of the T9-10 space with a 3 cm segment within the epidural space. Test dose was given to confirm the proper placement of the catheter. Epidural was activated with total bolus dose of 14 mL of bupivacaine 0.125% with fentany l.2 μg/mL. After 15 min, GA was induced with inj. thiopentone 200 mg, vecuronium 6 mg and fentanyl 100 μg and maintained with oxygen, N2O (nitrous oxide) and sevoflurane with intermittent positive-pressure ventilation (IPPV). Patient was haemodynamically stable during intubation and incision. The retroperitoneal mass was globular, cystic, 10 cm×8.5 cm and situated between the aorta and the inferior vena cava. While dissecting the cyst, there appeared sudden tachycardia, 125/ min and hypertension, 235/134 mmHg. This was followed by ventricular bigeminy initially and, later, idioventricular rhythms with varying, altered pulse beats. Inj. lignocaine 80 mg IV was injected, the plane of anaesthesia deepened with increasing concentrations of sevoflurane and additional doses of propofol 50 mg and fentanyl 75 μg were administered. Tachycardia was controlled with metaprolol 3 mg IV. As hypertension persisted, nitroglycerine infusion, 2 μg/kg/min, was started after an initial bolus of 50 μg. The patient was stabilised at a pulse rate of 54/ min and BP of 161/82 mmHg, 12 min following the crisis, but a grossly elevated ST of 2.5 mm persisted [Table 1]. Nitroglycerine infusion was titrated, the requirement remaining around 2–6 μg/kg/min for the first half an hour of the crisis, and tapered off subsequently. ST segment was elevated 1.1 mm at the end of the 40th min. The patient was reversed with inj. neostigmine 2.0 mg and inj. glycopyrolate 0.4 mg, IV, and extubation was performed. Epidural infusion with bupivacaine 0.125% was continued till the first episode of hypotension (80/56 mmHg), which appeared at the 75th min of crisis. Hypotension was managed with infusion of 1000 mL of 0.9% saline. Epidural opioid (tramadol 50 mg in 12 mL of saline, 0.9%) in 8-hourly bolus doses was continued for post-operative analgesia along with inj. diclofenac 75 mg, IM, twice daily.

Table 1

Recorded vital readings, with ST changes

In the immediate post-operative period, serum electrolytes showed potassium 3.9 meq/L, sodium 134 meq/L and blood sugar 139 mg/dL. ECG showed no ST elevation, but T inversions in the lateral leads were noted. Enzyme creatinine kinase-MB (CKMB) was 20 U/L. Echocardiogram did not show any wall motion abnormality. Repeat ECG and CKMB were normal at the 10th h, with normalised T waves. A second episode of hypotension (80/60 mmHg) was observed at the 17th h, and managed with fluids (Hetastarch 6% and saline 0.9%). Subsequently, the patient was stable. The 24-h urinary vanillyl mandelic acid (VMA) study done on urine collected on Day 1 of surgery showed an elevated value (17 mg/d).

DISCUSSION

0.1% of the hypertensives will have either a pheochromocytoma or paraganglioma.[1] Patients may present with episodic or continuous hypertension.[1] Our patient had no hypertension on admission or previously. Probable diagnosis of a catecholamine-secreting tumour was made only after observation of intraoperative haemodynamic events. In Michelle and colleagues’ study[6] of 143 patients, where the perianaesthetic risks and outcomes of pheochromocytoma and paraganglioma resection were assessed, less than 2% of the patients were “intraoperatively diagnosed” as in our case.

Handling the tumour is known to precipitate vascular “CRISIS”. Intraoperative episodes of hypertension with other cardiovascular events like tachycardia, sweating, pulmonary oedema and acidosis in the absence of an obvious cause should alert one to the possibility of a missed neural crest tumour.[1] Occurrence of arrhythmias with non-Q antero-inferior wall infarction in a hypertensive patient during resection of a pre-operatively undiagnosed abdominal paraganglioma under halothane anaesthesia has been reported.[7] Notwithstanding the possible correlation between the use of halothane and the arrhythmias in the above-reported case, paraganglioma or pheochromocytoma should be considered in any patient with hypertension and ischaemic heart disease undergoing resection of an uncharacterised retroperitoneal tumour. Previous studies[6] suggest that intraoperative dysrrhythmias occur less often with pre-operative “beta-blocked” patients, although sustained hypertension can still occur. “Prepared” patients may not enter the phase of “crisis” that was observed in our case.

Our patient did not have past history of hypertension, flushing, headache or any other related symptoms suggestive of a catecholamine-secreting neoplasm. Intubation and incision responses too were absent, in contrast to other reported cases.[78] Hence, a vasoactive neoplasm was not suspected until much later during the surgery. Our patient had a lower thoracic epidural catheter in situ, which was activated 30 min prior to the incision, and this probably suppressed the incision-related hypertensive response. Successful use of combined regional and GA is rarely reported in the literature.[19] By blocking parietal pain signals, the regional technique would be expected to partially mute the catecholamine response, although catecholamines could yet act at the vascular level and overcome the blockade.[1] A combined epidural with GA may be a better choice for a retroperitoneal tumour resection than GA alone. A theoretical disadvantage of the combined approach however may be the blunted induction and incision response itself that may not give the surgical team an opportunity to abort the procedure, pending further evaluation.

Hypertension was controlled using nitroglycerine and by deepening the plane of anaesthesia. Control of hypertensive episodes can be successfully achieved with the use of sodium nitroprusside[610] or nitroglycerine[10] infusions, and their dosage can also be titrated. ST elevations following arrhythmias with normal myocardial enzymes may be indicative of acute coronary spasms in response to circulating vasoactive agents.

Hypotension in our case did not immediately follow the ligation of the tumour vessels, in contrast to others reports,[7] and neither did she require vasopressors post-operatively. Noradrenaline or adrenaline are recommended only when fluid boluses are ineffective.[1] Management of circulating blood volume in these patients is essential pre-operatively; however, an increased circulating blood volume may not prevent hypotension.[11] Two factors might have influenced the hypotension episode; first being myocardial depression following arrhythmias; second, the use of metaprolol. Use of β-blockers alone is not recommended[10] in an unprepared patient, although not all agree with the same.[12] Alpha blockers should precede β-blockers; otherwise, a higher mortality is claimed.[13] Alternatively, inj. labetolol could have been used, which has both α- and β-receptor blocking actions.

No specific tumour markers were studied pre-operatively as the working diagnosis was a retroperitoneal cyst. A 123I-labeled metaiodobenzylguanidine scan for diagnosis of neuroendocrine tumours is ideally advised in such patients. However, the intraoperative diagnosis was confirmed by histopathological report of paraganglioma and high urinary VMA within the first day following surgery. A possibility of MEN type IIA too should be suspected, which our patient did not suffer from. Our case report highlights the importance of suspecting and appropriately investigating for a paraganglioma or pheochromocytoma in every case of retroperitoneal tumour, even in a haemodynamically asymptomatic patient. It behoves the anaesthesiologist to be well prepared in such cases for management of acute life-threatening perioperative events. Combined epidural and GA may be preferred for a retroperitoneal tumour excision. Malignant hyperthermia, thyrotoxic crisis and central anticholinergic syndrome may be some of the differential diagnoses one can consider for volatile intraoperative haemodynamic events.