Mechanism underlying lens fogging and its countermeasure in laparoscopic surgery

During laparoscopic surgery, visualization is fogged due to the influence of temperature. Fogging on the laparoscopic lens heightens the difficulty of the procedure. Therefore, the aim of this study was to analyse thermodynamics in laparoscopy.

A temperature sensor was attached to the laparoscopic tip and the abdominal cavity of five swine under general anaesthesia. The laparoscope was inserted into the abdominal cavity for five minutes after heating its tip with 65 °C saline for 10-300 s. The defogged laparoscope was wiped at room temperature for 10-300 s. Then, the laparoscope was inserted into the abdominal cavity for five minutes.

The temperature five minutes after insertion was similar for the 10-300 s heating durations (approximately 32.0 °C). There was no fogging when the laparoscope was wiped for 10-30 s. Two fogging events occurred when it was wiped for 60 s (temperature difference: -3.5 °C, -4.6 °C). Five fogging events were observed immediately after insertion when it was wiped for 300 s.

This study showed that the heating time was more than ten seconds to prevent fogging. We found that fogging occurred when the laparoscopic tip temperature was 3.5 °C lower than the abdominal cavity temperature.