CT-guided paravertebral block for microwave ablation of kidney tumors: a new technique

In patients undergoing computed tomography (CT)-guided microwave ablation (MWA) for renal tumors, we developed a CT-guided anterior paravertebral block (PVB) associated with anesthesia of the kidney capsule and inhalation of an equimolar mixture of oxygen and nitrous oxide (EMONO). The primary objectives were to describe our technique and to study its efficacy in terms of procedural success. The secondary objective was to study the tolerance by evaluating patient pain scores and the number of complications. Patients suffering from renal carcinoma classified T1a and considered to be poor candidates for surgery were included in this prospective, single-center pilot study. They underwent MWA under CT-guided loco-regional anesthesia: an anterior variant of the PVB at the level of T10, ipsilateral to the renal MWA associated with anesthesia of the kidney capsule and EMONO. Technical success was defined as total thermal ablation without additional sedation and no side effect during the procedure. Maximal pain score during the procedure was assessed using a visual analog score. Four patients were included. All procedures were technical success. No side effects were reported, either due to the procedure or anesthesia. The maximal pain score recorded immediately after procedure was 2 ± 2.4 on the visual analog score. MWA of the kidney is feasible under CT-guided anterior paravertebral block. PVB is well tolerated and can be associated with anesthesia of the kidney capsule and EMONO. This new technique may be an alternative to general anesthetic or conscious sedation in clinical practice.