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An unusual cause of respiratory distress and hypotension following removal of a pheochromocytoma

Chandigarh, India

To the Editor:

Pheochromocytomas account for 0.1–1% of all causes of hypertension¹ and their surgical removal successfully cures hypertensive episodes. Although a vast body of literature is available concerning perioperative problems and management,^2,3 we report an unusual cause of respiratory distress with hypotension in the immediate postoperative period.

A 17-yr-old male, weighing 50 kg was diagnosed with pheochromocytoma. The hypertension was controlled with doxazocin, amlodepine and atenolol. After fulfilment of Roizen’s criteria,⁴ surgery was planned. Antihypertensives were continued until the day of the procedure. Routine monitoring was augmented by direct arterial and central venous pressure (CVP) monitoring. Induction with midazolam, fentanyl and thiopentone was followed by maintenance with vecuronium, oxygen, nitrous oxide and isoflurane. Intraoperative hypertension was managed with a nitroglycerine infusion. Transient hypotension after tumour excision required volume expansion with saline, plasma and hydroxyethyl starch. After reversal of neuromuscular blockade and extubation, the patient was moved to recovery.

Thirty minutes later, the patient became incoherent, tachypneic with shallow respiration and desaturation (SpO₂ 80%). Blood gas analysis revealed a PaO₂ 58 mmHg and PaCO₂ 47 mmHg. Simultaneously, hypotension (80 mmHg systolic) required treatment with iv fluids, noradrenaline and dopamine. CVP, however, remained elevated (15 cm H₂O). The patient was reintubated and ventilation controlled. Reduced chest expansion and excessive peak airway pressure (60 cm H₂O) were observed. Persistent hypotension suggested the possibility of intra-abdominal bleeding, as confirmed by a four-quadrant tap. Re-exploration of the abdomen revealed the collection of blood clots (approximately 1 L) close to the diaphragm and inferior vena cava (IVC). After removal of the clots, blood pressure returned to 130/80 mmHg, CVP decreased to 9 cm H₂O and inotropes could be withdrawn gradually. Chest expansion improved and the peak airway pressure decreased to 20 cm H₂O. The patient remained hemodynamically stable and was extubated uneventfully after ventilation overnight.

Respiratory distress after excision of a pheochromocytoma is not routinely anticipated. The diagnosis of intra-abdominal bleeding was overlooked initially since it did not present as abdominal distension, owing to the muscular build of the patient. Instead, it pushed the diaphragm up and presented as respiratory distress.

Hypotension following pheochromocytoma resection is generally attributed to a chronically low circulating blood volume⁵ and to the abrupt fall in catecholamines following excision, a mechanism we held as the first possibility. Hence, we did not suspect, initially, that the hypotension resulted from the pressure exerted by clots on the IVC, though an elevated CVP should have alerted us.

Eventually, both respiratory distress and hypotension were found to be due to a common causative factor i.e., intra-abdominal blood clots, as their removal resulted in an immediate clinical improvement.

References

1 Bravo EL. Evolving concepts in the pathophysiology, diagnosis and treatment of pheochromocytoma. Endocr Rev 1994; 15: 356–68.[Medline]

2 O’Riordan JA. Pheochromocytoma and anesthesia. In: Desborough J (Ed.) Endocrine Disorders and Anesthesia. International Anesthesiology Clinics. Philadelphia: Lippincot-Raven, 1997; 35: 99–127.

3 Desmonts JM, le Houelleur J, Remond P, Duvaldestin P. Anaesthetic management of patients with phaeochromocytoma: a review of 102 cases. Br J Anaesth 1977; 49: 991–8.[Abstract/Free Full Text]

4 Roizen MF. Anesthetic implications of concurrent diseases. In: Miller RD (Ed.). Anesthesia, 5^th ed. Philadelphia: Churchill Livingstone 2000; 903: 1015.

5 Brunjes S, Johns VJ, Crane MG. Pheochromocytoma: Postoperative shock and blood volume. N Engl J Med 1960; 262: 393–6.

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