title: A newly developed scavenging system for administration of nitrous oxide during labour: safe occupational use.
abstract: OBJECTIVE
  Nitrous oxide (N(2) O) is routinely used as an analgesic in obstetrics during labour. Epidemiological studies have linked chronic occupational exposure to N(2) O to specific health problems, including reproductive risks. Occupational exposure limits (OELs) allow the use of N(2) O once appropriate preventive and safety measures have been taken. We assessed the effectiveness of a scavenger system (Anevac P-system®, Medicvent Heinen & Löwestein Benelux, Barneveld, the Netherlands) applied in N(2) O administration during labour in a midwifery-led birthing centre in the Netherlands.
  
  
  METHODS
  After informed consent, non-pregnant midwives were trained to administer N(2) O. N(2) O 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.
  
  
  CONCLUSIONS
  The Anevac P-scavenging system during N(2) O 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 N(2) O as analgesic during labour.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Obstetrics & Prenatal Medicine, Erasmus Medical Centre, Rotterdam, The Netherlands. j.vanderkooy@erasmusmc.nl
authors.forename: J
authors.initials: J
authors.lastname: van der Kooy
authors.forename: J P
authors.initials: JP
authors.lastname: De Graaf
authors.forename: Z M
authors.initials: ZM
authors.lastname: Kolder
authors.forename: K D
authors.initials: KD
authors.lastname: Witters
authors.forename: E
authors.initials: E
authors.lastname: Fitzpatrick
authors.forename: J J
authors.initials: JJ
authors.lastname: Duvekot
authors.forename: I J J
authors.initials: IJ
authors.lastname: Dons-Sinke
authors.forename: E A P
authors.initials: EA
authors.lastname: Steegers
authors.forename: G J
authors.initials: GJ
authors.lastname: Bonsel
mesh_terms: D000280:Administration, Inhalation; D000327:Adsorption; D000395:Air Pollutants, Occupational / Q000009:adverse effects*; D016902:Air Pollution, Indoor; D016362:Analgesia, Obstetrical / Q000295:instrumentation* / Q000379:methods; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage* / Q000009:adverse effects; D016550:Birthing Centers; D005260:Female; D015920:Gas Scavengers; D006801:Humans; D007747:Labor Stage, First; D008397:Masks; D008452:Maximum Allowable Concentration; D008880:Midwifery; D009609:Nitrous Oxide / Q000008:administration & dosage* / Q000009:adverse effects; D016273:Occupational Exposure; D010100:Oxygen / Q000008:administration & dosage; D011247:Pregnancy; D014691:Ventilation / Q000295:instrumentation
chemical_list: D000395:Air Pollutants, Occupational; D018712:Analgesics, Non-Narcotic; D009609:Nitrous Oxide; D010100:Oxygen