Is $CO_{2}$ Gas Insufflation in Endoscopic Thyroidectomy Safe or Not?: A Prospective Study through the Continuous Measurement of the End-tidal $CO_{2}$ Pressure

Purpose: Endoscopic thyroidectomy has recently been widely used in clinical practice. The operative method can be classified into CO2gas insufflation and the gasless technique. This study assessed the safety of low pressure CO2gas insufflation (up to 6 mmHg) by performing continuous measurement of the end-tidal CO2 (ETCO2) pressure. Methods: From March 2003 to October 2006, 95 patients (90 hemithyroidectomies and 5 total thyroidectomies) underwent endoscopic thyroidectomy. The low pressure CO2gas insufflation technique was applied in all cases. The ETCO2 pressure of the patients was measured by capnometry at the time of a pre-CO2gas insufflation status (0 minutes) and at the time of post-CO2gas insufflation (30 minutes) and then it was measured every 30 minutes with also performing capnograms. We analyzed the ETCO2 pressure at the time of the pre-CO2gas insufflation status (0 min) and we compared this with that of each status by using paired T-test. Results: For all 95 cases, the mean patient age was 36.2±9.1 (range: 21∼57 years), the mean tumor size was 1.7±1.1 (range: 0.1∼4.5 cm) and the mean operative time was 135.0±46.1 (range: 50∼340 min). The mean ETCO2 pressure (mmHg) was 33.0±3.9 at the time of pre-CO2gas insufflation status (0 min); the mean ETCO2 pressure was 31.1±3.7 at 30 min (n=95), 33.5±3.7 at 60 min (n=95), 35.2±3.6 at 90 min (n=95), 34.9±3.7 at 120 min (n=90), 34.6±3.8 at 150 min (n=70), 34.1±3.4 at 180 min (n=40), 34.3±5.2 at 210 min (n=15) and 34.0±4.2 at 240 min (n=9). There was a significant difference the early post-CO2gas insufflation status (P＜0.05 at 30 min, 90 min, 120 min), but there was no significant difference in the late post-CO2gas insufflation status (P＞0.05; at 60 min, 150 min, 180 min, 210 min, 240 min). At each time point, the ETCO2 pressures were all within the normal range. Conclusion: We successfully performed endoscopic thyroidectomy with using the low pressure CO2gas insufflation technique and there were no significant complications. We think that performing endoscopic thyroidectomy with using the low pressure CO2gas insufflation technique is a safe procedure. (J Korean Surg Soc 2007;73:290-293)