Quantitative Assessment of Nitrous Oxide Levels in Room Air of Operation Theaters and Recovery Area: An Observational Study.

Background: Nitrous oxide has been used during surgical anesthesia for many years. However, information about occupational exposure and related risks due to NO exposure to the health care personnel in India are still poorly understood. Here, we measured the residual NO levels during the working time of operation theatre room air in our tertiary care hospital.

Material And Methods: The air samples were collected from different anesthesia exposure zones on different days for quantitative analysis of available NO in the room air in respective areas. Nitrous oxide concentrations in the ambient air were also measured to compare outdoor and indoor levels.

Observations And Results: Nitrous oxide mixing ratios were found to be 65.61 ± 0.05 ppm, 281.63 ± 0.43 ppm, and 165.42 ± 0.42 ppm in elective surgical theatres of the hospital on three different days whereas in emergency operation theatres of the same hospital levels of NO were 166.75 ± 0.07 ppm, 510.19 ± 0.30 ppm and 2443.92 ± 0.64 ppm during same period. In elective pediatric surgical theatres levels of NO were found to be 1132.55 ± 0.70 ppm and 362.21 ± 0.13 ppm on two days of reading respectively. Outdoor levels of NO in contrast found 0.32 ± 0.01 ppm and was lower by a factor of 1000.

Conclusion: We observed the very high ambient concentration of NO in the surgical theatre's environment (up to 2443 ppm) and recovery areas (up to 50 ppm). It was 5 to 50 times higher ambient concentration of NO than REL in OT area and 200-7000 times higher ambient concentration of NO than outdoor ambient air in all surgical theaters other than CTVS OTs.