A newly developed scavenging system for administration of nitrous oxide during labour: safe occupational use

Objective Nitrous oxide (N2O) is routinely used as an analgesic in obstetrics during labour. Epidemiological studies have linked chronic occupational exposure to N2O to specific health problems, including reproductive risks. Occupational exposure limits (OELs) allow the use of N2O once appropriate preventive and safety measures have been taken. We assessed the effectiveness of a scavenger system (Anevac P-system (R), Medicvent Heinen & Lowestein Benelux, Barneveld, the Netherlands) applied in N2O administration during labour in a midwifery-led birthing centre in the Netherlands. Methods After informed consent, non-pregnant midwives were trained to administer N2O. N2O was delivered as a 50?:?50 mixture with oxygen and was self administered by the patient. The scavenging device, containing a double mask and a chin mask, was connected to the local evacuation system vented outside the building. Data on the 8-h time-weighted average (8-h TWA) as well as the 15-min TWA (15-min TWA) were obtained. Results Thirteen patients were included. Six patients were included in the first study period. In this period the 8-h TWA was not exceeded, however, in all patients, the 15-min TWA occasionally exceeded the OELs. After four additional measures, seven patients were included. After implementation of these measures, the 8-h TWA and 15-min TWA never exceeded the OELs. System leakage was not observed during both study periods. Conclusion The Anevac P-scavenging system during N2O analgesia in labour prevents exceeding OELs in professional workers. The scavenging system appeared acceptable and effective, and can be considered in hospital settings that use N2O as analgesic during labour.