New Bipolar Resection Device for Transurethral Resection of the Prostate: Firstex-Vivoandin-VivoEvaluation

Abstract

Bipolar resection systems for transurethral resection of the prostate (TURP) offer some advantages over conventional monopolar devices. As both the active and the return electrode are placed on the tip of the resectoscope, current flow is locally limited, and negative effects caused by the current flow through the patient's body in the monopolar array can theoretically be reduced. Furthermore, bipolar resectoscopes use 0.9% sodium chloride solution as irrigation fluid, and therefore, the risk of TUR syndrome is theoretically eliminated. In this trial, we evaluated a new bipolar resectoscope in an ex-vivo model and in vivo and compared it with a standard monopolar resection device. The modified model of the isolated blood perfused porcine kidney was used to determine cutting qualities, ablation rate, blood loss, and coagulation depth of the bipolar resection device compared with a monopolar resectoscope. A measurement system placed in the line between the generator and the patient was used to determine electric parameters when both resectoscopes were used in vivo. The ex-vivo evaluation showed worse cutting ability of the bipolar resection device compared with the monopolar resectoscope, with essential difficulties in starting a cut. The ablation rate was equal, as both resectoscopes had the same loop diameter. The bleeding rate was lower in bipolar (15.16+/-3.31 g/min) than monopolar (20.78+/-1.52 g/min) resection, whereas bipolar cutting resulted in marginally deeper coagulation zones (236.25+/-36.69 microm 216.0+/-42.25 microm). The in-vivo measurements made it clear that more power and more current is delivered to the patient during bipolar resection. The reason lies in a period at the beginning of each cut, when the patient's impedance is low and current flow high. Our results suggest that bipolar resection offers an alternative to conventional monopolar TURP. The advantage of a more localized energy field is at least in part compensated for by the higher generator output power during the procedure. Our ex-vivo results indicate a reduced bleeding rate compared with monopolar resection. Clinical studies have to be performed to prove the significance of our findings for patient treatment.