Nitrous Oxide Occupational Exposure in Conscious Sedation Procedures in Endoscopic Ambulatories: A Pilot Retrospective Observational Study in an Italian Hospital

Abstract

Background: Nitrous oxide is widely used to induce sedation; however, its use outside of operating rooms – such as in ambulatory rooms – is not properly controlled by norms. In the lack of supervision, 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 with a first step marked by nitrous oxide environmental testing in a gastroenterology outpatient care where colonoscopies were practiced; environmental research was supported by biological monitoring with urinary N2O analysis in exposed operators. The research was conducted in the absence and then in the presence of a collective security device (Niki mask). Results: The study was rolled out in 10 sessions of day shift procedures, totaling 4105 samples. The average nitrous oxide 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 (Anova test p.001). Biological testing revealed a substantial rise in urinary concentration of 8.97 (p.001) between the start and the end of the shift, and the use of the Niki mask was effective (p=.003). Conclusions: The exposure levels reported in environmental sampling exceed the limits of 50 ppm (the value set for operating rooms in Italy) as well as the value of 25 ppm (NIOSH threshold value), indicating a significant issue in the outpatient use of nitrous oxide. It is evident that technical measures are needed to contain the occupational risk from Nitrous oxide exposure outside of operating rooms, and that even the basic use of Niki masks would not be sufficient to minimize professional exposure and protect workers; for the exposure results detected in this research, it is also plain that exposures must be subject to health surveillance.