Specifications

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The Medigas 3010 was kept plugged in and on (with the pump off) during the down time. The
Medigas 3010 had to be kept on due to the 15 minute warm up time required and only a few
minutes warning was given prior to the use of nitrous oxide.
4.2.5 Passive Dosimeter Badges
At the beginning of each shift the charge nurse assigned patients to each nurse. Nitrous oxide
passive dosimeter badges and badges were given to two to four nurses following this assignment.
Badges were given to those nurses most likely to work with a labouring patient and were worn
on the lapel for the duration of the shift (8 or 12 hours). The badges were removed at the end of
the shift. The shift duration, number of deliveries and whether exposure to nitrous oxide
occurred was recorded for each badge. One blank badge was analyzed for every 10 air samples
taken.
It was noted at the end of the first shift that the badges kept falling out of their plastic holders.
Conversations with Assay Technologies, manufacturer of the badges, indicated that problems
have been reported with the holder and using masking tape to secure the disk containing the
absorbent to the back of the badge would not interfere with sampling or the results. Masking
tape was used for the remainder of the shifts.
Lab analysis was conducted at the WCB lab using Analytical Method 1102 Passive Dosimeter
Method. This method involved analysis with a gas chromatograph equipped with an electron
detector. The error of this method was +/- 25%.
4.2.6 Ventilation Testing
The volume of fresh air entering the room was tested in one of the labour and delivery rooms
using the Alnor balometer Jr. The flow rate was tested for each of the three fresh air supplies in
the room. A ventilation balance report, dated 1999, obtained from Chris Thompson, Systems
Engineer, LMH, was used to calculate the number of air changes per hour.