Purpose: An anticoagulated animal model was tested to evaluate estimated acute blood loss (EABL) following tissue ablation with 3 modalities of radio frequency (RF) thermal energy.
Materials and methods: Four groups of randomly divided rabbits were established. Group 1 (3 control and 3 anticoagulated rabbits) underwent sham treatment (noRF), group 2 (2 control and 7 anticoagulated) received single probe dry RF (dRF) (475 KHz and 5 W for 2 minutes), group 3 (2 control and 7 anticoagulated) received single probe wet RF (wRF) (475 KHz with 14.6% hypertonic saline at 50 W for 40 seconds) and group 4 (3 control and 7 anticoagulated) was treated with vapor RF (vRF) (0.9% normal saline for 10 seconds). Oral warfarin sodium was the anticoagulant. Following a midline incision ablation was performed on the left kidney and liver. Pre-weighed gauze pads were used to collect EABL for a 5-minute observation period after needle probe removal. Temperature data were recorded from the right kidney using fiberoptic thermocouples. Lesions were grossly inspected and measured.
Results: Anticoagulation resulted in super anticoagulated animals with an average prothrombin time of almost 140 seconds. EABL was the least from the ablated left kidney for vRF (50 mg), followed by wRF (260 mg), dRF (390 mg) and noRF (1,800 mg). EABL was the least from the liver for vRF (10 mg), followed by wRF (470 mg), dRF (1,260 mg) and noRF (2,680 mg). A greater percent of total ablative time at 10 mm was spent at greater than 50C during wRF and vRF. Measured ablative lesions size was largest following vRF ablation.
Conclusions: The thermal coagulative effects of RF ablation resulted in less bleeding compared with controls in this orally anticoagulated animal model. The novel RF modality vRF is introduced.