The purpose of he study is to evaluate effects of dexmedetomidine on pain during radiofrequency ablation of liver and kidney tumours.

Although radiofrequency ablation (RF) is accepted as the best therapeutic choice for patients with early stage hepatocellular carcinoma when liver transplantation or surgical resection are not suitable options, it is still performed only in a few hospitals and experience is so far limited (Goldberg & Ahmed, 2002; Shiina et al., 2005). In addition, RF ablation is emerging as a viable alternative to surgery for inoperable patients with limited hepatic metastatic disease, especially from colorectal cancer. Although radiofrequency ablation has been accepted as a safe and effective treatment for liver and kidney tumours, there are few studies addressing periprocedural pain.

Thus, the optimal anaesthetic procedure is still to be determined. Currently at our institution RF is performed as monitored sedation procedure using remifentanil infusion supplemented with midazolam boluses, when considered necessary. However, when using remifentanil and midazolam combination it is quite difficult to avoid too deep respiratory depression.

Dexmedetomidine is an α2-adrenoreceptor agonist with sedative, analgesic and anxiolytic effects, and it has more selective α2-adrenergic effect than clonidine. Dexmedetomidine has a great deal of potential in this arena given its analgesic and anxiolytic properties while preserving respiratory drive (Bergese SD et al., 2010).

All patients will receive dexmedetomidine 0.4 µg/kg/hr infusion from the start of procedure. The infusion will be continued during the whole RF procedure.

At the same time all patients will receive remifentanil infusion according to TCI (target controlled infusion) protocol. Plasma concentration target will be set from 0.5 ng/ml and, if necessary, will be increased to achieve a comfortable state of patient (Ramsey Sedation Scale: 2-3).

Inclusion Criteria:

• liver or/and kidney cancer for which radiofrequency ablation procedure is planned
• signed informed consent form

Exclusion Criteria:

• patient refusal
• pregnancy
• known allergy to dexmedetomidine or remifentanil
• atrioventricular block grade II or III or other significant cardiac conduction disturbance
• stroke
• low blood pressure not responding to treatment