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Implementing nitrous oxide cracking technology in the labour ward

Implementing nitrous oxide cracking technology in the labour ward to reduce occupational exposure and environmental emissions: a quality improvement study.

A.Pinder, et al. 

Anaaesthesia 2022, 77, 1228-1236


2021-22 study to ascertain the impact of cracking technology on birthing room nitrous oxide levels.

Mean ambient nitrous oxide levels were recorded during the last 30 minutes of uncomplicated labours in 36 cases across 3 UK hospitals.


Baseline levels without the cracking unit were established over 12 readings: mean 45.4ppm, range 1.4-172.4ppm.


The cracking unit was then used with three different patient interfaces:

  1. mouthpiece; 8 measurements: mean 13.05, range 0-64.9ppm; 71% lower vs baseline
  2. cushion face mask; 8 measurements: mean 7.5ppm, range 0-234.2ppm; results were too variable to meet criteria for significance.
  3. low profile face mask: 8 measurements: mean 8.7ppm, range 0-27.3ppm; 81% lower vs baseline.


22 midwives who used the equipment were surveyed with generally positive feedback.

19 commented that the unit “could be smaller”

8 reported faults with the cracking unit comprising 5 overheating events and 3 malfunctions.

4 described the noise level as unacceptable

The authors note a limitation of this quality improvement study was the lack of strict research protocols especially regarding patient selection/exclusion.


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