Quantification of insensible water loss associated with insufflation of nonhumidified CO2 in patients undergoing laparoscopic surgery

A growing number of surgical procedures of increased duration are being performed using laparoscopic techniques. No study to date has quantitated the potential insensible water loss associated with laparoscopic surgical procedures as a result of intra-abdominal humidification of insufflated nonhumidified CO2 gas. The purpose of this study was to quantitate this insensible water loss by measuring the CO2 gas volume consumed and the relative humidity of the vented gas. Ten patients presenting for elective procedures were enrolled in this descriptive prospective IRE-approved study. After secondary trocar placement and attainment of the desired intra-abdominal pressure, vented laparoscopic gas was passed directly through a dewpoint monitor sensor. Determinations of dewpoint and gas temperature were made immediately after the start of the surgical procedure and every 15 minutes thereafter until completion. Dew-point temperature was converted to relative humidity, which was used to determine the water vapor content of the gas. The actual water content (absolute humidity) of the vented laparoscopic gas was then calculated from the water vapor volume. The mean relative humidity of the vented laparoscopic gas was 92.2% +/- 0.8%. The mean laparoscopic gas flow rate was 42.0 +/- 5.0 L/h. The mean volume of water (absolute humidity) loss attributed to humidification of dry CO2 was found to be less than 1 mL/h, Insufflation of dry CO2 during laparoscopic procedures therefore results in insignificant insensible water loss.