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Dexmedetomidine for resection of a large phaeochromocytoma with invasion into the inferior vena cava
Editor—Dexmedetomidine is increasingly used in patients on mechanical ventilation in intensive care units.1 Perioperative use of dexmedetomidine provides a steady haemodynamic course and blunts fluctuations at stressful moments like intubation and extubation.2 In phaeochromocytoma surgery, dexmedetomidine could be a useful anaesthetic adjunct in minimizing episodes of abrupt arterial hypertension expected during manipulation of the tumour. We report use of dexmedetomidine in a patient with a large phaeochromcytoma with invasion into the inferior vena cava (IVC), in whom adrenalectomy with excision of the invaded part of IVC was planned. The patient received a 2-week course of phenoxybenzamine and propanolol before surgery. On arrival in the operating theatre, arterial pressure through an intra-arterial catheter in the left radial artery measured 120/65 mm Hg. A loading dose of dexmedetomidine 2 mg kg–1 was infused over 10 min followed by an infusion at 0.7 mg kg–1 h–1. Anaesthesia was induced with fentanyl 100 mg, thiopentone 250 mg, rocuronium 50 mg and esmolol 30 mg. The highest arterial pressure (AP) during intubation was 145/80 mm Hg. Intraoperative monitoring included ECG, AP, CVP, saturation, end-tidal carbon dioxide and volatile agent, airway pressure and temperature. Anaesthesia was maintained with isoflurane 0.6% in oxygen and nitrous oxide, remifentanil at 0.1 mg kg–1 min–1 and cisatracurium. Labetalol 20 mg had been administered before direct tumour manipulation. During direct tumour manipulation, the remifentanil was increased to 0.2–0.3 mg kg–1 min–1. Sodium nitroprusside was administered at a low dose between 0.2 and 0.7 mg kg–1 min–1. Two doses of esmolol 20 mg were given to control spurious increase in AP. The AP during dissection around the tumour ranged from 80/40 to 145/90 mm Hg. Upon clamping of IVC, the remifentanil, nitroprusside and dexmedetomidine infusions were stopped. During the IVC clamping period of 25 min, the AP was stabilized with phenylephrine and epinephrine (total dose of 1 mg and 340 mg, respectively), and ranged from 70/35 mm Hg to 120/65 mm Hg. Upon release of the IVC clamp, the AP dropped to 80/40 mm Hg, which quickly returned to above 110/60 mm Hg with fluid and dopamine infusion. The dopamine infusion was stopped before the end of surgery (total dose 5.81 mg). The surgery lasted 4 h 21 min and the patient was extubated awake uneventfully 15 min later. A morphine patient-controlled anaesthesia was prescribed for postoperative pain relief. The patient made an uneventful recovery.
In resection of a large phaeochromocytoma with IVC invasion, haemodynamic instability especially with severe episodic hypertension from surgical stimuli and tumour manipulation are expected. Preoperative 
-blockade, intraoperative vasodilators and increasing anaesthetic depth are common measures to smoothen out the haemodynamic course and prevent hypertensive crises.3 Remifentanil is effective in blunting the sympathetic response to noxious stimuli and has been used in phaeochromocytoma excision to control intraoperative haemodynamic instability,4 but significant hypotension and bradycardia, and a large increase in plasma catecholamine levels and marked hypertension during manipulation have been reported.5 Dexmedetomidine, a highly selective 2-adrenoceptor agonist, has sedative and analgesic properties.6 It attenuates sympathoadrenal responses to tracheal intubation and surgical stimuli and has a significant anaesthetic-sparing effect when used intraoperatively.7 8 In order to blunt the intubation stress, we administered a high loading dose of dexmedetomidine of 2 mg kg–1 before induction and the patient remained haemodynamically stable during intubation. After the loading dose, the infusion was maintained at 0.7 mg kg–1 h–1 until clamping of the IVC. In the remaining surgery, haemodynamic stability was maintained with inotropic support, which was stopped at the end of surgery.
In summary, we describe the management of a patient for excision of a large phaeochromocytoma with invasion into a major vessel, in whom dexmedetomidine was found a useful anaesthetic adjunct to maintain steady haemodynamics and to prevent abrupt hypertensive crises.
Hong Kong, China
References
1 Venn RM, Bradshaw CJ, Spencer R, et al. Preliminary UK experience of dexmedetomidine, a novel agent for postoperative sedation in the intensive care unit. Anaesthesia 1999; 54: 1136–42[CrossRef][Web of Science][Medline]
2 Talke P, Chen R, Thomas B, et al. The hemodynamic and adrenergic effects of perioperative dexmedetomidine infusion after vascular surgery. Anesth Analg 2000; 90: 834–9
3 Desmonts JM, Marty J. Anaesthetic management of patients with phaeochromocytoma. Br J Anaesth 1984; 56: 781–9
4 Breslin DS, Farling PA, Mirakhur RK. The use of remifentanil in the anaesthetic management of patients undergoing adrenalectomy: a report of three cases. Anaesthesia 2003; 58: 358–62[CrossRef][Web of Science][Medline]
5 Gande AR, Ambler JJS, Haw MP, Gill RS. Remifentanil for phaeochromocytoma resection. Anaesthesia 2003; 58: 196–7[Web of Science][Medline]
6 Ebert, TJ, Hall JE, Barney JA, et al. Effects of increasing plasma concentrations of dexmedetomidine. Anesthesiology 2000; 93: 382–94[CrossRef][Web of Science][Medline]
7 Scheinin B, Lindgren L, Randell T, et al. Dexmedetomidine attenuates sympathoadrenal responses to tracheal intubation and reduces the need for thiopentone and peroperative fentanyl. Br J Anaesth 1992; 68: 126–31
8 Aho M, Erkola O, Kallio A, et al. Dexmedetomidine infusion for maintenance of anesthesia in patients undergoing abdominal hysterectomy. Anesth Analg 1992; 75: 940–6
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