Principles determining optical clarity in endoscopic surgery

In laparoscopy the view is often hindered by soiling or condensation on the front lens of the endoscope, In this study the physical conditions of the endoscope in laparoscopic surgery were initially determined in an animal model. The intra-abdominal CO2 was found to rapidly equilibrate to body temperature and become nearly 100% saturated with water, These conditions were duplicated in a controlled inanimate model to investigate the physical principles of clear endoscopic vision. The temperature of the distal end of the laparoscope was observed to vary between 32 degrees C and 40 degrees C in the typical intra-abdominal environment. Vision is unimpeded by condensation on the front lens if it is maintained at temperatures greater than the body temperature of 37 degrees C. The authors suggest implementation of a controlled heating device in laparoscope design to sustain clear vision in endoscopic surgery without the need for extracorporeal cleaning cycles, Because CO2 insufflation to the front lens and rinsing liquid cool the optic and favour reactive fogging, the whole optic has to be warmed up.