Aims

To report a rare and complex case of acute hypertensive crisis and catecholamine-induced intestinal pseudo-obstruction in a patient with metastatic paraganglioma.

Clinical Features

RM, a 49 year old male diagnosed with metastatic paraganglioma was admitted to the Intensive Care Unit (ICU) for management of acute hypertension. Consistently elevated Systolic Blood Pressure (SBP) above 230mmHg was likely precipitated by excess catecholamine release from metastatic paraganglioma, and six-day history of severe constipation and distended tympanic abdomen leading to poor absorption of his regular oral medicines including sunitinib for tumour control, phenoxybenzamine for inhibition of catecholamine secretion, perindopril and amlodipine for hypertension.

Management and outcome

RM’s oral medicines were withheld until constipation had resolved except oral phenoxybenzamine, which was increased to 100mg/day in the absence of a parenteral formulation in Australia. Infusions of sodium nitroprusside and glyceryl trinitrate were commenced and titrated to maximum dose. However target SBP less than 160mmHg and target mean arterial pressure less 75mmHg could not be reached.   Phentolamine 0.5-1mg was administered every 20-30 minutes intravenously as adjunctive therapy and subsequently converted to a continuous infusion of 21.6mg/day which reduced SBP by 40mmHg to 180mmHg. With consumption of phentolamine exceeding stock holdings across pharmacy wholesalers, intermittent infusions of labetalol were commenced as second line therapy. Intestinal obstruction did not resolve until neostigmine was administered intravenously. Hospital executive approval was sought to procure metyrosine, an oral catecholamine-release inhibitor, from overseas. After 10 days in ICU, SBP was normalised and RM was discharged to the ward and then home 7 days later for ongoing management of intestinal pseudo obstruction and hypertension with oral pyridostigmine and antihypertensives respectively.

Conclusion

Pharmacological options currently available in Australia for acute hypertensive crises are limited. Timely access to specialist medicines and availability of point of care decision support for prevention and management of this rare complication of paraganglioma is needed.