Tumour cell movement during heating and humidification of insufflating CO2: an in vitro model.

BACKGROUND

Intra-operative hypothermia and port-site recurrence have been associated with laparoscopic surgery. Heating and humidification of insufflating CO2 may protect against laparoscopy-associated hypothermia. However, the effect of heated, humidified CO2 upon tumour cell movement is unknown.

METHODS

Twenty-four in vitro studies that used 4-L plastic bottles were performed. Thirteen million human colorectal cancer cells were placed in each bottle. Twelve studies used dry room temperature CO2 for insufflation: the remaining 12 used heated, humidified CO2 as the insufflating gas. Both groups were subdivided into bottles with leaks around the trocars and with airtight sealing around the trocars. Two trocars and a laparoscopic grasper were used. The exiting insufflating gas was filtered and examined for the presence of cells. Laparoscopic instruments agitated the contents of the bottles. The instruments and trocars were washed. These washings were examined for the presence of cells.

RESULTS

Heated, humidified CO2 insufflation was able to maintain a warmer and more humid environment within the bottles when compared with dry room-temperature CO2. No cells were detected on the gas filters. Tumour cells were found on 12 out of 12 instruments and 11 out of 12 trocars with dry CO2 insufflation. Tumour cells were found on 8 out of 12 instruments and 7 out of 12 trocars with heated humidified CO2 insufflation. The only statistically significant difference in tumour cell spread to trocars was found between heating and humidification when no leak was present, and heating and humidification with leak present, and dry insufflation with no leak present (P = 0.015, Fisher's two-tailed exact test).

CONCLUSIONS

Heating and humidifying CO2 during in vitro laparoscopy does not increase the aerosolization of tumour cells when compared with dry CO2. However, the use of heated and humidified gas with airtight seals around the trocars in vitro may lessen cell deposition on trocars.