Retrograde intrarenal surgery (RIRS) represents a standard procedure for kidney stone removal, especially in stone sizes up to 2 cm. However, due to material wear, RIRS is a cost intensive procedure. Recently, single-use flexible ureterorenoscopes have been introduced to improve budget predictability in RIRS. Influence on operative quality and risk of complications using these devices warrants further evaluation. In the present study, we objected to systematically assess differences in physical and optical properties of single-use devices in comparison to standard reusable endoscopes.
In two single-use (LithoVue™ single-use digital flexible ureterorenoscope, Boston Scientific; Pusen Uscope UE3011™, Medical Video Endoscope), and one reusable ureterorenoscope (Flex-Xc™, Karl-Storz Endoscopes), we investigated flow-rates, flexion, illuminance, and intrarenal pressure in a porcine kidney model. Subjective image quality was assessed using a standardized questionnaire. Common insertable devices (Zero Tip™ stone basket, Boston Scientific; Sensor™ guide wire, Boston Scientific; 365micm laser fiber) were applied to investigate additional influence on physical properties.
Significant variability in maximum flow rates was observed between the endoscopes (Pusen™: 33.4 ml/min, LithoVue™: 30.3 ml/min, Flex-Xc™: 25.8 ml/min, P<0.05). Application of a guide wire into the working channel resulted in a high reduction of both, flow rates (Pusen™: 2.1 ml/min, LithoVue™: 1.93 ml/min, Flex-Xc™: 1.2 ml/min) and maximum flexion in all ureteroscopes. Moreover, flexion led to a reduction of absolute flow rates up to 7.9% (Pusen™). During instrumentation, maximum intranenal pressure was measured with 90 cmH2O (Pusen™) as compared to 51cmH2O and 40 cmH2O (LithoVue™; Flex-Xc™), respectively. Illuminance at 20mm / 50mm object distance was 2160 lux / 428 lux (Pusen™), 9090 lux / 1857 lux (Flex-Xc™), and 5733 lux/ 1032 lux (LithoVue™), respectively (p<0.05). Subjective image quality score was highest (24.1±0) using the Flex-Xc™ endoscope, as compared to LithoVue™ (21.0±2.71) and Pusen™ (20.1±3.02).
Despite economic issues regarding the choice of either single-use or reusable flexible ureterorenoscopes, significant differences in physical and optical properties are present, with putative influence on surgical efficacy, complications, and patient outcomes. Therefore, further comparative evaluation of single-use and reusable endoscopes in a clinical scenario is useful. With regard to high intrarenal pressure during RIRS, additional utilization of ureteral access sheaths may be considered to avoid renal damage.