Non-interventional study evaluating exposure to inhaled, low-dose methoxyflurane experienced by hospital emergency department personnel in France

Abstract

Objectives: Low-dose methoxyflurane is a non-opioid, inhaled analgesic administered via the Penthrox inhaler and was recently licensed in Europe for emergency relief of moderate-to-severe trauma-associated pain in conscious adults. This non-interventional study investigated occupational exposure to methoxyflurane in the hospital emergency department (ED) personnel during routine clinical practice.

Setting and participants: The study was conducted in two hospital ED triage rooms in France over a 2-week and 3-week period, respectively. Low-dose methoxyflurane analgesia was self-administered by patients via the inhaler under the supervision of nursing staff, per routine clinical practice. An organic vapour personal badge sampler was attached to the uniform of the nurses working in the treatment rooms throughout an 8-hour shift (total of 140 shifts during the study period). Seven-day ambient air monitoring of each treatment room was also performed. Methoxyflurane levels adsorbed in each badge sampler were measured by a central laboratory. The primary objective was to evaluate methoxyflurane exposure experience by the hospital ED nurses during an 8-hour shift.

Results: In 138 badge samplers, the median (range) concentration of methoxyflurane present following 8-hour nursing shifts was 0.017 (0.008, 0.736) ppm. This level was almost 900-fold lower than the previously reported 8-hour-derived maximal exposure level of 15 ppm; methoxyflurane exposure approaching this threshold was not documented in any badges. There was no correlation between the number of applications of low-dose methoxyflurane administered during a shift (range 0-5) and the vapour exposure measured on the personal badge samplers.

Conclusions: This study indicates that nurses working in hospital EDs experience very low levels of occupational exposure to methoxyflurane vapour during routine clinical practice. These real-world data can provide reassurance to healthcare providers supervising patients receiving low-dose methoxyflurane analgesia via a Penthrox inhaler; further studies may inform exposure in other hospital ED settings.

Keywords: analgesia; exposure; methoxyflurane; penthrox.

Figure 1

Use of the Penthrox inhaler (permission to reproduce the image was provided by Mundibiopharma limited).

Figure 2

3M Organic Vapour Monitor 3500 packaging box and badge sampler (permission to reproduce the image was provided by 3M).

Figure 3

Methoxyflurane concentrations over time, as detected in personal badge samplers worn by emergency room nurses during 8-hour shifts. Maximum TWA exposure level of 15 ppm during an 8-hour period (hashed line) was based on a previously reported extrapolation of nephrotoxicity data obtained from anaesthetised patients receiving high-dose methoxyflurane. TWA, time-weighted average.

Figure 4

Box plots capturing methoxyflurane concentrations measured in personal badge samplers worn by emergency room triage nurses during 8-hour shifts. Box represents IQR and median values. Whiskers represent the minimum (first quartile –1.5×IQR) and maximum (third quartile +1.5×IQR). Outliers are shown in circles. Methoxyflurane concentrations were below the quantification limit (1 µg/sample) in 30 and 31 badge samplers from Cochin Hospital and Tenon Hospital, respectively. For calculation purposes, these samples were assigned a concentration of 0.7 µg.

Figure 5

Methoxyflurane vapour concentrations measured in personal badge samplers* and number of Penthrox applications per day. *Worn by emergency room triage nurses throughout an 8-hour shift.