Nitrous oxide occupational exposure in conscious sedation procedures in endoscopic ambulatories: a pilot retrospective observational study in an Italian hospital.

Summary: Introduction. Nitrous oxide (N2O) is widely used to induce sedation also outside of operating rooms; there is a chance of workplace exposures for the operators engaged in the outpatient use of nitrous oxide. The aim of this research is to assess nitrous oxide exposure in gastroenterology outpatient settings. Methods. We performed an observational study marked by N2O environmental testing in a gastroenterology outpatient care; environmental research was supported by biological monitoring with urinary N2O analysis in exposed operators. The research was conducted both without and using a collective security device (NIKI mask). Results. The study was rolled out in 10 sessions of day shift procedures, totaling 4105 samples. The average N2O concentration in the environment was 27.58 (SD 1.76) and 449.59 (SD 35.29), respectively with and without NIKI Mask; the distribution of gases in the environment under investigation was not homogeneous (Anovatest P=0.001). Biological testing revealed a substantial rise in urinary concentration of 8.97 (p=0.001) between the start and the end of the shift, and the use of the NIKI-mask was effective (p=.003). Discussion. The exposure levels reported exceed the limits of 50 ppm (Italy operating rooms threshold value) as well as the value of 25 ppm (NIOSH threshold-value), indicating a significant issue in the outpatient use of N2O. Technical measures are needed to contain the occupational risk from N2O exposure outside of operating rooms; for the exposure results detected in this research, it is also evident that workers exposed to N2O must be subject to adequate health surveillance accounting for this occupational risk.