Endoscopic tissue liquidisation of the prostate, bladder and kidney

Abstract

Endoscopic techniques have revolutionised the practice of all specialities of surgery. Endoscopic access has been either via a natural route, such as the urethra, or percutaneously, as in percutaneous intrarenal stone surgery. Potential endoscopic procedures for bulk tissue removal have been limited by the need to reduce that tissue to a size smaller than the endoscopic channel used. An attempt has been made to create a device that will liquidise and aspirate tissue through an endoscope, This Instrument has been called the Endoscopic Liquidiser and Surgical Aspirator (ELSA). This report details the design and development of the ELSA which has led to its clinical application. The device is 5 mm in diameter and is used through a specially made endoscope of 8.5 mm outer diameter (approximately 27 French). It consists of a high speed rotating blade mounted in a housing that provides irrigation for efficient 1iquidisation and a channel for aspiration of the tissue. Laboratory evaluation was measured by the removal rates of different tissues. The optimum parameters of blade speed, irrigation flow and aspiration were established after a series of controlled experiments. Blade shape was also found to be important and a study of the material strengths of different tissues was required to establish that blade design should vary for each tissue used. Under optimum laboratory conditions fresh human prostate could be removed at 2.4 g/min and renal cortex at 14.6 g/min. The resultant aspirate contained particles ranging from 10 microns to 3 mm, but the majority were less than 200 microns. Flow cytometry was required as the only reasonable method of rapid pathological diagnosis. The action of the ELSA did not confer any Inherent haemostatic benefit and a diathermy plate was added to the tip of the instrument. The ELSA was successfully used to remove benign prostatic tissue from 7 patients with bladder outflow obstruction. However the procedures were slow and visualisation was poor once the liquidisation began. The mean operating time was 85 minutes (range 50 - 120). 1 patient suffered a fatal capsular perforation, but otherwise morbidity v/as not dissimilar from a control group undergoing a standard transurethral diathermy resection. 6'7 patients regained an improved stream with good control. The ELSA was used in the same transurethral method for the removal of superficial bladder tumours in 10 patients. The same problem of impaired vision was found, but the removal was very rapid as one would expect with a soft non-fibro\\is material. The postoperative morbidity was greater than in a control group using a diathermy resectoscope due to bladder perforation with the ELSA in 1 case. A percutaneous endoscopic nephrectomy has been achieved in 2 dogs. Each kidney was embolised with "Ethibloc" (a material that completely occupies all arterial capillary beds), An Intrarenal approach was compared with an extrarenal, retroperitoneal one; the latter using carbon dioxide insufflation. Both procedures were successful. Haeraostasis was not a problem. These may be suitable clinical techniques for the minimally invasive removal of infected kidneys prior to transplantation. The presence of stones would not be a problem because of the ability of the ELSA to fragment and aspirate stone particles as efficently as any ultrasound device. This was confirmed in a series of laboratory tests on various stone types and in 5 patients with urinary stones. An extension of the concept of minimally invasive bulk tissue aspiration is the integration of robotics into this form of surgery. The ELSA has been attached to an industrial robot. The mechanism of a transurethral prostatectomy has been studied in order to program the robot. A robotic prostatectomy in a simulation model has been performed. Each procedure can be preprogrammed according to the dimensions of the gland. The in vitro study confirmed that the robot was consistent and therefore safe; and rapid (mean removal