Modelling levels of nitrous oxide exposure for healthcare professionals during EMONO usage

Abstract

BackgroundComputational fluid dynamics (CFD) has been used to compute nitrous oxide (N2O) levels within a room during the administration of an equimolar mix of N2O/oxygen (EMONO) in the clinical setting. This study modelled realistic scenarios of EMONO usage in hospital or primary care, in order to estimate the potential N2O exposure of healthcare professionals (HCP) with routine EMONO use and to provide guidance for EMONO users.MethodsSixteen scenarios were defined by carrying out a survey of practitioners. CFD simulations were performed for each scenario and N2O concentrations over time were calculated. N2O exposures (time-weighted average of concentration over 8 h [TWA-8 h]) were calculated at the HCPs’ mouth to be compared with a predefined occupational exposure limit (OEL).ResultsAdministration duration and ventilation type were the main factors influencing N2O levels; ventilation type also influenced wash-out time between EMONO administrations. N2O concentration showed a plume distribution towards the ceiling and was highly heterogeneous, highlighting the importance of measurement location. Although estimated TWA-8 h varied widely, 13 of the 16 scenarios had an N2O TWA-8 h of <100 parts per million.ConclusionsData demonstrate that EMONO usage in well ventilated rooms – as recommended – helps to ensure that N2O exposure does not exceed the OEL and does not signal any major risks for HCPs when recommendations are followed. Although these data are numerical simulations and should be considered as such, they can provide guidance for EMONO users.

Procedural analgesia with nitrous oxide at home for epidermolysis bullosa

“…as a time-weighted average in the operating room during the period of general anesthesia. [ 18 ] The N 2 O concentration after 15 minutes of auto administration by a patient with an on-demand valve system in a 10 m 2 emergency room without evacuation system has been estimated to be of 4.2 time-weighted average- 8 hours p.p.m. [ 10 ] This scenario resembles the conditions of our clinical case, which presents 2 to 3 times of the N 2 O exposure (30–45 minutes maximum) but a longer washout time (48 hours compared with 20 minutes in the clinical simulation).…”

“…The administration of an N 2 O/O 2 mixture in well-ventilated rooms with an on-demand valve and for short-duration procedures would ensure that N 2 O exposure remains below the critical values. [ 18 ] An alternative option may be to use a delivery system incorporating a double-face mask and a portable scavenging device, the use of which has been shown to maintain ambient N 2 O levels within the recommended limits. [ 19 ]…”

Initiating Intrapartum Nitrous Oxide in an Academic Hospital: Considerations and Challenges

“…Health care providers who work with women using N 2 O can measure the degree of their personal exposure by wearing N 2 O‐sensitive dosimeter badges. The risk from occupational exposure to N 2 O is measured by exposure over time . Dosimeter testing at UNMH was planned quarterly for the first year of use and then annually per the National Institute for Occupational Safety and Health (NIOSH) standards .…”

“…Early studies of midwives’ exposure in the United Kingdom were done in poorly ventilated rooms without the use of scavenging (gas evacuation) equipment . Demand valves in well‐ventilated rooms reduce exposure below the recommended limits of 25 parts per million . Although the full extent of occupational exposure risk may not be known, safety practices and staff training in overseeing proper patient mask use can limit exposure.…”

Implementing an emissions-rate model in computational fluid dynamics simulations of contaminant diffusion processes: A case study with xylene in painting workshops

“…Both experimental 7–12 and computational fluid dynamics (CFD) simulations 13–16 have been frequently used to investigate the air quality of residential areas. Several researchers 17–19 have focused on the air distribution of workshops.…”