Specifications

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The average exposure data collected for the Miran were higher than the average exposure data
collected by the Medigas 3010. This would be expected since the Miran was an environmental
sample and was in the room with the patient for the entire labour and delivery. The nurse
wearing the Medigas 3010 went in and out of the room during the early stages of labour and
remained in the room during the active labour. The maximum exposures for the nurses (spikes
on the graph) were higher with the Medigas 3010 when the nurses were working close to the
mother’s face. The Miran had a maximum of 312.6 ppm and therefore it is not possible to
determine actual level reached. The Miran was located approximately 3 feet from the mothers
face at all times and therefore one would expect the personal sampler to have higher levels if the
nurse worked near the mother’s face.
Deliveries 2, 4, 5, 6, 7, 8 used only nitrous oxide and no other means of analgesia during the
delivery and Deliveries 1, 3 and 9 used nitrous oxide and Demorol/Gravol and/or an epidural.
Delivery 2 used nitrous oxide for the entire delivery and the overall exposure levels were quite
low. The activity log for this delivery indicates that the mother used the gas very regularly, kept
the mask on the majority of the time (continuous not intermittent use), did not talk very much
and therefore did not off-gas high nitrous oxide levels into the room. This patient was monitored
using the Medigas for the first 47 minutes of her labour.
The activity log for Delivery 3 indicates that the mother exhaled into the mask when the gas was
being used and therefore the scavenging system was able to remove a large portion of the
exhaled gas. An epidural was administered at 7:10 pm and nitrous oxide use ceased.
Delivery 4 walked around using the portable nitrous oxide from 2:20 pm to 2:39 pm. A large
spike of 352 ppm occurred at 2:21 pm when the nurse was assisting the mother in the hallway.
The labour then continued in the shower using the room (piped in) nitrous oxide until 3:10 pm
when Entonox use ceased and the mother moved back to the bed. The baby was delivered at
3:32 pm and the gas was used during the stitches from 3:36 to 3:44. In this delivery, the nurse
was situated close to the mother’s head for all of the occasions when nurse’s exposure exceeded
125 ppm.